Hip
Anders Troelsen, Georgios Tsikandylakis, Kristian Mortensen, Kirill Gromov, Henrik Malchau, Maziar Mohaddes
Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital; Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital
Background: In the quest for hip arthroplasty implants that last the lifespan of patients improvements are still needed. Improved fixation and stability of the acetabular cup f could potentially be achieved with higher porous structures facilitating bony ingrowth.
Purpose / Aim of Study: We aimed to investigate if a novel porous titanium (OsseoTi) surface provides a superior early cup fixation compared with the well-established porous plasma spray (PPS) surface in total hip arthroplasty (THA) and if the use of larger metal heads could affect the early cup fixation in uncemented THA.
Materials and Methods: 96 patients were randomized to receive either an OsseoTi or a PPS cup, as well as, either the largest possible (36-44 mm) or a standard 32- mm metal head in vitamin E cross-linked polyethylene (VEPE) liner. Patients were followed at 2 years with RSA, plain x-rays and patient reported outcome measures. The primary outcome was proximal cup migration and cup rotation comparing the OsseoTi with the PPS cups as well as large head THA with 32-mm THA. The secondary outcome was the presence of radiolucencies and patient reported outcome between patients with OsseoTi and PPS cups.
Findings / Results: The mean proximal cup migration (95% confidence interval) was 0.18 (CI=0.09 to 0.26) mm for the OsseoTi and 0.24 (0.16 to 0.32) mm for the PPS. Large head THA had a mean proximal cup migration of 0.20 (0.13 to 0.26) mm and 32-mm THA had 0.21 (CI=0.11 to 0.31). No significant cup rotation around the X-axis was observed in any group. The presence of radiolucencies and patient reported outcome did not differ between OsseoTi and PPS cups.
Conclusions: The use of the OsseoTi surface provides a stable cup fixation equal to the use of the PPS surface. Larger metal heads were not inferior to 32-mm heads regarding early cup fixation. Longer-term studies on the safety profile of the novel OsseoTi cup and larger heads are required before they can be routinely used in THA.
Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital; Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital; Dept. of Orthopaedic Surgery, Sahlgrenska University Hospital
Background: In the quest for hip arthroplasty implants that last the lifespan of patients improvements are still needed. Improved fixation and stability of the acetabular cup f could potentially be achieved with higher porous structures facilitating bony ingrowth.
Purpose / Aim of Study: We aimed to investigate if a novel porous titanium (OsseoTi) surface provides a superior early cup fixation compared with the well-established porous plasma spray (PPS) surface in total hip arthroplasty (THA) and if the use of larger metal heads could affect the early cup fixation in uncemented THA.
Materials and Methods: 96 patients were randomized to receive either an OsseoTi or a PPS cup, as well as, either the largest possible (36-44 mm) or a standard 32- mm metal head in vitamin E cross-linked polyethylene (VEPE) liner. Patients were followed at 2 years with RSA, plain x-rays and patient reported outcome measures. The primary outcome was proximal cup migration and cup rotation comparing the OsseoTi with the PPS cups as well as large head THA with 32-mm THA. The secondary outcome was the presence of radiolucencies and patient reported outcome between patients with OsseoTi and PPS cups.
Findings / Results: The mean proximal cup migration (95% confidence interval) was 0.18 (CI=0.09 to 0.26) mm for the OsseoTi and 0.24 (0.16 to 0.32) mm for the PPS. Large head THA had a mean proximal cup migration of 0.20 (0.13 to 0.26) mm and 32-mm THA had 0.21 (CI=0.11 to 0.31). No significant cup rotation around the X-axis was observed in any group. The presence of radiolucencies and patient reported outcome did not differ between OsseoTi and PPS cups.
Conclusions: The use of the OsseoTi surface provides a stable cup fixation equal to the use of the PPS surface. Larger metal heads were not inferior to 32-mm heads regarding early cup fixation. Longer-term studies on the safety profile of the novel OsseoTi cup and larger heads are required before they can be routinely used in THA.
Lars Lykke Hermansen, Bjarke Viberg, Søren Overgaard
Department of Orthopaedics & The Orthopaedic Research Unit, Hospital of South West Jutland, Esbjerg & Odense University Hospital; Department of Orthopaedic Surgery and Traumatology, Lillebaelt Hospital, University hospital of Southern Denmark; The Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: It is well-known that there is a substantial risk of re-dislocation and eventually revision after the first dislocation following primary THA, but knowledge about patient-reported outcomes (PRO) after dislocation and closed reduction is lacking.
Purpose / Aim of Study: Our aim was to report on health- and hip- related quality of life (QoL) in patients with dislocation following primary THA due to osteoarthritis.
Materials and Methods: We conducted a cross-sectional, matched case-control study involving patients registered in the Danish Hip Arthroplasty Register between 2010 and 2014. Dislocations were captured in the Danish National Patient Register using a validated algorithm. We matched patients with dislocation 1:2 upon age, sex, date and hospital of primary surgery to patients without dislocation. They received two PRO questionnaires (EQ- 5D, HOOS) and three patient satisfaction items. Results are descriptively compared using mean with 95% confidence intervals.
Findings / Results: We identified 1,010 living patients with dislocation. The response rate was 70.1%. Mean follow-up was 7.2 years from index surgery and 4.9 years from the latest dislocation. Patients without dislocation reported a higher EQ-5D VAS score of 75.6 (74.5-76.7) compared to 67.8 (65.9-69.7) in the dislocation group. Regarding hip-related QoL, patients with dislocation reported a lower HOOS-QoL domain score of 62.8 (60.2-65.4) compared to 82.9 (81.7-84.1) in the control group (100=no problems, 0=extreme problems). Even after five years from the latest dislocation, the HOOS-QoL score was still low, demonstrated by 65.6 (62.0-69.2) points. The other HOOS domains were consistently 8-10 points worse after dislocation. Regarding satisfaction, only 59% reported either an “excellent” or a “very good” overall result after experiencing dislocations, as opposed to 85% for the controls.
Conclusions: This is the first national case-control study on PRO after hip dislocation. The study showed that both health- and hip-related QoL is markedly and persistently reduced compared to a control group even 2-5 years after the latest dislocation. The most important aspect must be to avoid the first episode of dislocation, since the full relieving potential for this THA is never achieved.
Department of Orthopaedics & The Orthopaedic Research Unit, Hospital of South West Jutland, Esbjerg & Odense University Hospital; Department of Orthopaedic Surgery and Traumatology, Lillebaelt Hospital, University hospital of Southern Denmark; The Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: It is well-known that there is a substantial risk of re-dislocation and eventually revision after the first dislocation following primary THA, but knowledge about patient-reported outcomes (PRO) after dislocation and closed reduction is lacking.
Purpose / Aim of Study: Our aim was to report on health- and hip- related quality of life (QoL) in patients with dislocation following primary THA due to osteoarthritis.
Materials and Methods: We conducted a cross-sectional, matched case-control study involving patients registered in the Danish Hip Arthroplasty Register between 2010 and 2014. Dislocations were captured in the Danish National Patient Register using a validated algorithm. We matched patients with dislocation 1:2 upon age, sex, date and hospital of primary surgery to patients without dislocation. They received two PRO questionnaires (EQ- 5D, HOOS) and three patient satisfaction items. Results are descriptively compared using mean with 95% confidence intervals.
Findings / Results: We identified 1,010 living patients with dislocation. The response rate was 70.1%. Mean follow-up was 7.2 years from index surgery and 4.9 years from the latest dislocation. Patients without dislocation reported a higher EQ-5D VAS score of 75.6 (74.5-76.7) compared to 67.8 (65.9-69.7) in the dislocation group. Regarding hip-related QoL, patients with dislocation reported a lower HOOS-QoL domain score of 62.8 (60.2-65.4) compared to 82.9 (81.7-84.1) in the control group (100=no problems, 0=extreme problems). Even after five years from the latest dislocation, the HOOS-QoL score was still low, demonstrated by 65.6 (62.0-69.2) points. The other HOOS domains were consistently 8-10 points worse after dislocation. Regarding satisfaction, only 59% reported either an “excellent” or a “very good” overall result after experiencing dislocations, as opposed to 85% for the controls.
Conclusions: This is the first national case-control study on PRO after hip dislocation. The study showed that both health- and hip-related QoL is markedly and persistently reduced compared to a control group even 2-5 years after the latest dislocation. The most important aspect must be to avoid the first episode of dislocation, since the full relieving potential for this THA is never achieved.
Kristine Bunyoz, Georgios Tsikandylakis, Kristian Mortensen, Gromov Kirill, Maziar Mohaddes, Henrik Malchau, Anders Troelsen
Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Hvidovre Hospital
Background: Corrosion at the head-neck junction in total hip arthroplasty (THA) is considered a potential concern as it might result in material loss and adverse local tissue reaction (ALTR). Elevated blood metal ions could be used as an indicator of corrosion. Lager femoral heads may contribute to increased taper corrosion by creating greater friction torques at the head-neck junction. However, it is controversial whether large heads are the predisposing factor for corrosion.
Purpose / Aim of Study: To investigate the effect of femoral head size on blood metal ion levels on vitamin E cross-linked polyethylene (MoVEPE) THA, comparing 36-44 mm heads with 32 mm heads.
Materials and Methods: As part of a randomized controlled single blinded trial, 96 patients were randomized to receive either the largest possible metal head (36mm-44 mm) that could be accommodated in the thinnest available VEPE insert or a 32 mm femoral head. Participants blood levels of titanium, chrome and cobalt ions were collected at 1 and 2- years follow-up.
Findings / Results: At 1-year follow-up, median (interquartile range) cobalt, chrome and titanium blood level did not differ between the groups: 0.119 µg/L (0.083-0.158) for 32 mm versus 0.122 µg/L (0.075-0.224) for 36-44 mm, (p=0.663), 0.500 µg/L (0.500-0.585) for 32 mm versus 0.500 µg/L (0.500-1.163) for 36- 44 mm, (p=0.050), 1.575 µg/L (1.343-2.033) for 32 mm versus 1.500 µg/L (1.220-1.870) for 36-44 mm, (p=0.456). At 2-years follow-up, median cobalt, chrome and titanium blood levels did not differ between groups: 0.146 µg/L (0.124-0.242) for 32 mm versus 0.161 µg/L (0.116-0.259) for 36-44 mm, (p=0.9113), 0.500 µg/L (0.500-0.500) for 32 mm versus 0.500 µg/L (0.500-0.511) for 36-44 mm, (p=0.5426), 1.540 µg/L (1.148-1.895) for 32 mm versus 1.350 µg/L (1.018-1.708) for 36-44 mm, groups (p=0.1631).
Conclusions: No difference in blood metal ions was found between the groups. Choosing the largest possible head size (36-44 mm) over a 32 mm head in MoVEPE does not seem to elevate blood metal ion levels up to 2 years postoperatively. As taper corrosion is probably time-dependent, longer-term reports are needed to evaluate the association between large metal heads and blood metal ion levels.
Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Hvidovre Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Sahlgrenska University Hospital; Department of orthopaedics, Hvidovre Hospital
Background: Corrosion at the head-neck junction in total hip arthroplasty (THA) is considered a potential concern as it might result in material loss and adverse local tissue reaction (ALTR). Elevated blood metal ions could be used as an indicator of corrosion. Lager femoral heads may contribute to increased taper corrosion by creating greater friction torques at the head-neck junction. However, it is controversial whether large heads are the predisposing factor for corrosion.
Purpose / Aim of Study: To investigate the effect of femoral head size on blood metal ion levels on vitamin E cross-linked polyethylene (MoVEPE) THA, comparing 36-44 mm heads with 32 mm heads.
Materials and Methods: As part of a randomized controlled single blinded trial, 96 patients were randomized to receive either the largest possible metal head (36mm-44 mm) that could be accommodated in the thinnest available VEPE insert or a 32 mm femoral head. Participants blood levels of titanium, chrome and cobalt ions were collected at 1 and 2- years follow-up.
Findings / Results: At 1-year follow-up, median (interquartile range) cobalt, chrome and titanium blood level did not differ between the groups: 0.119 µg/L (0.083-0.158) for 32 mm versus 0.122 µg/L (0.075-0.224) for 36-44 mm, (p=0.663), 0.500 µg/L (0.500-0.585) for 32 mm versus 0.500 µg/L (0.500-1.163) for 36- 44 mm, (p=0.050), 1.575 µg/L (1.343-2.033) for 32 mm versus 1.500 µg/L (1.220-1.870) for 36-44 mm, (p=0.456). At 2-years follow-up, median cobalt, chrome and titanium blood levels did not differ between groups: 0.146 µg/L (0.124-0.242) for 32 mm versus 0.161 µg/L (0.116-0.259) for 36-44 mm, (p=0.9113), 0.500 µg/L (0.500-0.500) for 32 mm versus 0.500 µg/L (0.500-0.511) for 36-44 mm, (p=0.5426), 1.540 µg/L (1.148-1.895) for 32 mm versus 1.350 µg/L (1.018-1.708) for 36-44 mm, groups (p=0.1631).
Conclusions: No difference in blood metal ions was found between the groups. Choosing the largest possible head size (36-44 mm) over a 32 mm head in MoVEPE does not seem to elevate blood metal ion levels up to 2 years postoperatively. As taper corrosion is probably time-dependent, longer-term reports are needed to evaluate the association between large metal heads and blood metal ion levels.
Karen Dyreborg, Mikkel R. Andersen, Nikolaj Winther, Søren Solgaard, Gunnar Flivik, Michael M. Petersen
Department of Orthopaedic Surgery, Rigshospitalet and Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Skåne University Hospital; Department of Orthopaedic Surgery, Rigshospitalet
Background: Despite the good results with modern total hip arthroplasty (THA) new implants are continuously being developed to meet the demand for even longer durability. The Echo Bi-Metric (EBM) THA stem is the successor to the Bi Metric (EBM) THA stem is the successor to the Bi-Metric (BM) THA stem. The EBM uses many of the features of the BM while incorporating new design attributes to augment the clinical performance.
Purpose / Aim of Study: The purpose of this study was to compare the migration behavior with radiostereometric radiostereometric analysis (RSA) of the EBM stem in comparison to the BM stem during the first 24 months and to evaluate the clinical outcome.
Materials and Methods: We randomized 62 patients with o osteoarthritis (mean age=64 years, F Female/Male=28/34) scheduled for an u uncemented THA to receive either an E EBM or a BM THA stem. We performed RSA within a week after surgery and at 3, 6, 12 and 24 months. The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS).
Findings / Results: During the first 3 months both the EBM and the BM stems showed obvious subsidence (-2.53 mm and -2.22 mm respectively), and retroversion ( 2.51° and 2.24° respectively). From 3 to 24 months, however, there is only slight and statistically insignificant migration without any difference between the groups. The expected increase in HHS and OHS is observed without statistical difference between groups.
Conclusions: The EBM stem shows similar migration patterns as the precursor, the BM stem, and both seem to stabilize and osseointegrate osseointegrate after 3 months with satisfying clinical results measured up to 24 months.
Department of Orthopaedic Surgery, Rigshospitalet and Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Skåne University Hospital; Department of Orthopaedic Surgery, Rigshospitalet
Background: Despite the good results with modern total hip arthroplasty (THA) new implants are continuously being developed to meet the demand for even longer durability. The Echo Bi-Metric (EBM) THA stem is the successor to the Bi Metric (EBM) THA stem is the successor to the Bi-Metric (BM) THA stem. The EBM uses many of the features of the BM while incorporating new design attributes to augment the clinical performance.
Purpose / Aim of Study: The purpose of this study was to compare the migration behavior with radiostereometric radiostereometric analysis (RSA) of the EBM stem in comparison to the BM stem during the first 24 months and to evaluate the clinical outcome.
Materials and Methods: We randomized 62 patients with o osteoarthritis (mean age=64 years, F Female/Male=28/34) scheduled for an u uncemented THA to receive either an E EBM or a BM THA stem. We performed RSA within a week after surgery and at 3, 6, 12 and 24 months. The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS).
Findings / Results: During the first 3 months both the EBM and the BM stems showed obvious subsidence (-2.53 mm and -2.22 mm respectively), and retroversion ( 2.51° and 2.24° respectively). From 3 to 24 months, however, there is only slight and statistically insignificant migration without any difference between the groups. The expected increase in HHS and OHS is observed without statistical difference between groups.
Conclusions: The EBM stem shows similar migration patterns as the precursor, the BM stem, and both seem to stabilize and osseointegrate osseointegrate after 3 months with satisfying clinical results measured up to 24 months.
Nina Edwards, Claus Varnum, Søren Overgaard, Alma Pedersen
Department of Clinical Epidemiology, Aarhus University Hospital; Department of Regional Health Research, Department of Orthopaedic Surgery, Vejle Hospital, University of Southern Denmark; Department of Regional Health Research, Department of Orthopaedic Surgery and Traumatology, Department of Clinical Research, Odense University Hospital, University of Southern Denmark; Odense University Hospital,, Aarhus University Hospital
Background: In Denmark, all citizens are guaranteed free access to medical care, which should minimize the influence of socioeconomic status (SES). However, knowledge concerning the impact of SES on utilization of total hip arthroplasty (THA) is relatively sparse.
Purpose / Aim of Study: To examine the association between SES and the utilization of THA across different age groups and over time.
Materials and Methods: We conducted a population-based case-control study. From the Danish Hip Arthroplasty Register we included all patients undergoing primary THA due to osteoarthritis (cases) in Denmark from 1995 to 2017. The Danish Civil Registration System was used to select 5 population controls for each THA case, matched on sex, region of residence and surgery date/index date. We retrieved individual-level data on SES markers (education, income, and liquid assets) from Statistics Denmark. We used logistic regression to estimate adjusted odds ratios (aOR) with 95% confidence intervals for THA, adjusting for SES markers and comorbidity.
Findings / Results: A total of 108,946 THA cases and 544,730 population controls were identified. Among persons aged 45-55 years (youngest), we found a higher risk of THA (aOR 1.42 (1.32-1.53)) for those with the lowest education vs. highest education, as well as for those with the lowest vs. highest income (aOR 1.12 (1.02-1.23)). The association between education and income and higher risk of THA decreased with increasing age. On the contrary, the risk of a THA was lower for the youngest age group with the lowest vs. highest liquid assets (aOR 0.75 (0.70-0.80)). The risk of a THA was higher for persons with the lowest education vs. highest in the years 1995-2000 (aOR 1.23 (1.15-1.31)), which decreased in 2013-2017 (aOR 1.01 (0.97-1.05)). For the lowest income vs. the highest there was a higher risk of THA in 1995-2000 (aOR 1.22 (1.12-1.32)), decreasing to a lower risk in 2013-2017 (aOR 0.84 (0.80-0.89)).
Conclusions: The association between low level of education, low level of income, and higher risk of THA was observed among the youngest age group, but decreased with increasing age. The inequality in the risk of THA by education decreased over calendar time, whereas the inequality by income was persistent.
Department of Clinical Epidemiology, Aarhus University Hospital; Department of Regional Health Research, Department of Orthopaedic Surgery, Vejle Hospital, University of Southern Denmark; Department of Regional Health Research, Department of Orthopaedic Surgery and Traumatology, Department of Clinical Research, Odense University Hospital, University of Southern Denmark; Odense University Hospital,, Aarhus University Hospital
Background: In Denmark, all citizens are guaranteed free access to medical care, which should minimize the influence of socioeconomic status (SES). However, knowledge concerning the impact of SES on utilization of total hip arthroplasty (THA) is relatively sparse.
Purpose / Aim of Study: To examine the association between SES and the utilization of THA across different age groups and over time.
Materials and Methods: We conducted a population-based case-control study. From the Danish Hip Arthroplasty Register we included all patients undergoing primary THA due to osteoarthritis (cases) in Denmark from 1995 to 2017. The Danish Civil Registration System was used to select 5 population controls for each THA case, matched on sex, region of residence and surgery date/index date. We retrieved individual-level data on SES markers (education, income, and liquid assets) from Statistics Denmark. We used logistic regression to estimate adjusted odds ratios (aOR) with 95% confidence intervals for THA, adjusting for SES markers and comorbidity.
Findings / Results: A total of 108,946 THA cases and 544,730 population controls were identified. Among persons aged 45-55 years (youngest), we found a higher risk of THA (aOR 1.42 (1.32-1.53)) for those with the lowest education vs. highest education, as well as for those with the lowest vs. highest income (aOR 1.12 (1.02-1.23)). The association between education and income and higher risk of THA decreased with increasing age. On the contrary, the risk of a THA was lower for the youngest age group with the lowest vs. highest liquid assets (aOR 0.75 (0.70-0.80)). The risk of a THA was higher for persons with the lowest education vs. highest in the years 1995-2000 (aOR 1.23 (1.15-1.31)), which decreased in 2013-2017 (aOR 1.01 (0.97-1.05)). For the lowest income vs. the highest there was a higher risk of THA in 1995-2000 (aOR 1.22 (1.12-1.32)), decreasing to a lower risk in 2013-2017 (aOR 0.84 (0.80-0.89)).
Conclusions: The association between low level of education, low level of income, and higher risk of THA was observed among the youngest age group, but decreased with increasing age. The inequality in the risk of THA by education decreased over calendar time, whereas the inequality by income was persistent.
Thea Emily Benson, Ina Trolle Andersen , Søren Overgaard, Anne Marie Fenstad, Stein Atle Lie, Jan-Erik Gjertsen, Ove Furnes, Alma Becic Pedersen
Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus Denmark; Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus, Denmark; Department of Orthopedic Surgery and Traumatology and Department of Clinical Research, Odense University Hospital and University of Southern Denmark, Odense, Denmark; Department of Orthopedic Surgery and the Norwegian Arthroplasty Register, Haukeland University Hospital, Bergen, Norway; Department od Clinical Dentistry and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Medicine and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Medicine and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus, Denmark
Background: Thromboprophylactic agents are routinely administered in patients undergoing total hip arthroplasty (THA). Concerns have been raised if post-operative surgical site bleeding following the use of low molecular weight heparin (LMWH) or Non-Vitamin K antagonist oral anticoagulants (NOAC) leads to periprosthetic joint infection (PJI) that may require revision surgery. It is further unclear if bleeding can interfere with the initial implant fixation leading to increased revision rate due to aseptic loosening of the hip implant.
Purpose / Aim of Study: We examined the revision rate due to PJI, aseptic loosening and all-causes after primary THA in patients treated with LMWH versus non- vitamin K antagonist oral anticoagulant (NOAC) as thromboprophylaxis.
Materials and Methods: We conducted a prospective cohort study (n=53,605) based on data from the national hip arthroplasty registries in Denmark and Norway. The exposure was thromboprophylaxis (LMWH vs. NOAC) and the primary outcome was PJI at 1-year follow up. Secondary outcomes were aseptic loosening and all-cause revision at 5-year follow-up. Cumulative incidences were estimated including death as a competing risk. Cox proportional hazard model was applied to estimate crude and adjusted cause-specific hazard ratios (HRs). We adjusted for sex, age, Charlson Comorbidity Index, fixation type, start and duration of thromboprophylaxis, and preoperative use of Vitamin K antagonists, NOAC, aspirin, and platelet inhibitors.
Findings / Results: We included 40,451 patients in the LMWH group and 13,154 patients in the NOAC group. The 1-year cumulative incidence of revision due to PJI was 0.9% (0.8-1.0) in the LMWH group and 0.7% (0.6-0.8) in the NOAC group. During the entire follow-up period, the adjusted HR for revision due to PJI was 0.87 (0.68-1.12), 1.62 (1.25-2.11) for aseptic loosening, and 1.36 (1.16-1.59) for all-cause revision for NOAC versus LMWH.
Conclusions: No clinically important difference in revision rate due to PJI when comparing NOAC with LMWH was observed. However, a higher revision rate due to aseptic loosening and all-cause revision was observed in patients treated with NOAC compared to patients treated with LMWH.
Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus Denmark; Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus, Denmark; Department of Orthopedic Surgery and Traumatology and Department of Clinical Research, Odense University Hospital and University of Southern Denmark, Odense, Denmark; Department of Orthopedic Surgery and the Norwegian Arthroplasty Register, Haukeland University Hospital, Bergen, Norway; Department od Clinical Dentistry and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Medicine and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Medicine and the Norwegian Arthroplasty Register, University of Bergen, Bergen, Norway; Department of Clinical Epidemiology , Aarhus University Hospital, Aarhus, Denmark
Background: Thromboprophylactic agents are routinely administered in patients undergoing total hip arthroplasty (THA). Concerns have been raised if post-operative surgical site bleeding following the use of low molecular weight heparin (LMWH) or Non-Vitamin K antagonist oral anticoagulants (NOAC) leads to periprosthetic joint infection (PJI) that may require revision surgery. It is further unclear if bleeding can interfere with the initial implant fixation leading to increased revision rate due to aseptic loosening of the hip implant.
Purpose / Aim of Study: We examined the revision rate due to PJI, aseptic loosening and all-causes after primary THA in patients treated with LMWH versus non- vitamin K antagonist oral anticoagulant (NOAC) as thromboprophylaxis.
Materials and Methods: We conducted a prospective cohort study (n=53,605) based on data from the national hip arthroplasty registries in Denmark and Norway. The exposure was thromboprophylaxis (LMWH vs. NOAC) and the primary outcome was PJI at 1-year follow up. Secondary outcomes were aseptic loosening and all-cause revision at 5-year follow-up. Cumulative incidences were estimated including death as a competing risk. Cox proportional hazard model was applied to estimate crude and adjusted cause-specific hazard ratios (HRs). We adjusted for sex, age, Charlson Comorbidity Index, fixation type, start and duration of thromboprophylaxis, and preoperative use of Vitamin K antagonists, NOAC, aspirin, and platelet inhibitors.
Findings / Results: We included 40,451 patients in the LMWH group and 13,154 patients in the NOAC group. The 1-year cumulative incidence of revision due to PJI was 0.9% (0.8-1.0) in the LMWH group and 0.7% (0.6-0.8) in the NOAC group. During the entire follow-up period, the adjusted HR for revision due to PJI was 0.87 (0.68-1.12), 1.62 (1.25-2.11) for aseptic loosening, and 1.36 (1.16-1.59) for all-cause revision for NOAC versus LMWH.
Conclusions: No clinically important difference in revision rate due to PJI when comparing NOAC with LMWH was observed. However, a higher revision rate due to aseptic loosening and all-cause revision was observed in patients treated with NOAC compared to patients treated with LMWH.
Karen Dyreborg, Søren Solgaard, Michael Skettrup, Michael M. Petersen
Department of Orthopaedic Surgery, Rigshospitalet and Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Rigshospitalet
Background: Total hip arthroplasty (THA) has proven to be a successful procedure. But people are living longer and there is an increasing demand for an active retirement. Thus, attempts to increase the longevity of the implants by developing new ones seem necessary. developing new ones seem necessary.
Purpose / Aim of Study: The aim of this study was to evaluate how two different uncemented THA stems - the Echo Bi-Metric (EBM) and the Bi-Metric (BM) - compares regarding adaptive bone remodeling.
Materials and Methods: From February 2016 to September 2 2017 we randomized 62 patients, 1:1 ( (mean age=64 years, F Female/Male=28/34), scheduled for an u uncemented THA to receive either an E EBM or a BM THA stem. We performed dual-energy x-ray absorptiometry (DEXA) scans within a week after surgery and at 3, 6, 12 and 24 months with measurements of bone mineral density (BMD) in the 7 Gruen zones (region of interest (ROI) 1-7). The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS).
Findings / Results: We found a decrease in BMD between the postoperative and the 24-months values in all ROIs for both stems. The greatest decrease over time was seen for both groups in the ROI1 (BM =-8.4%, p=0.044, and EBM=-6.5%, p=0.001) and ROI7 (BM =-7%, p=0.005, and EBM=-8.6%, p<0.0005). We found a tendency in ROI2-4 towards different early bone remodeling pattern between the groups with a higher degree of bone loss in the EBM group. However, this difference only continued beyond 6 months in ROI4 (24 months: BM=-1.2% and EBM =-2.8%, p=0.001). The HHS score increased from 61 to 99 points in the BM and from 67 to 98 points the EBM group. The OHS score increased by 23 points in both groups. The final scores were close to the maximum for both measurements in both groups and we found no statistically significant differences between the groups.
Conclusions: Both stems show similar adaptive bone remodeling as well as satisfying clinical results.
Department of Orthopaedic Surgery, Rigshospitalet and Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Herlev-Gentofte Hospital; Department of Orthopaedic Surgery, Rigshospitalet
Background: Total hip arthroplasty (THA) has proven to be a successful procedure. But people are living longer and there is an increasing demand for an active retirement. Thus, attempts to increase the longevity of the implants by developing new ones seem necessary. developing new ones seem necessary.
Purpose / Aim of Study: The aim of this study was to evaluate how two different uncemented THA stems - the Echo Bi-Metric (EBM) and the Bi-Metric (BM) - compares regarding adaptive bone remodeling.
Materials and Methods: From February 2016 to September 2 2017 we randomized 62 patients, 1:1 ( (mean age=64 years, F Female/Male=28/34), scheduled for an u uncemented THA to receive either an E EBM or a BM THA stem. We performed dual-energy x-ray absorptiometry (DEXA) scans within a week after surgery and at 3, 6, 12 and 24 months with measurements of bone mineral density (BMD) in the 7 Gruen zones (region of interest (ROI) 1-7). The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS).
Findings / Results: We found a decrease in BMD between the postoperative and the 24-months values in all ROIs for both stems. The greatest decrease over time was seen for both groups in the ROI1 (BM =-8.4%, p=0.044, and EBM=-6.5%, p=0.001) and ROI7 (BM =-7%, p=0.005, and EBM=-8.6%, p<0.0005). We found a tendency in ROI2-4 towards different early bone remodeling pattern between the groups with a higher degree of bone loss in the EBM group. However, this difference only continued beyond 6 months in ROI4 (24 months: BM=-1.2% and EBM =-2.8%, p=0.001). The HHS score increased from 61 to 99 points in the BM and from 67 to 98 points the EBM group. The OHS score increased by 23 points in both groups. The final scores were close to the maximum for both measurements in both groups and we found no statistically significant differences between the groups.
Conclusions: Both stems show similar adaptive bone remodeling as well as satisfying clinical results.
Alma B. Pedersen, Aurélie Mailhac, Anne Garland, Søren Overgaard, Ove Furnes, Stein Atle Lie, Anne Marie Fenstad, Cecilia Rogmark , Johan Kärrholm, Ola Rolfson, Jaason Haapakoski, Antti Eskelinen, Keijo T. Mäkelä, Nils P. Hailer
Department of Clinical Epidemiology, Aarhus University Hospital, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Denmark; Department of Surgical Sciences/Orthopaedics, Uppsala University, Sweden; Department of Orthopaedic Surgery and Traumatology and the Danish Hip Arthroplasty Register, Odense University Hospital, Denmark; The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Dentistry, University of Bergen, Bergen, Norway; The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Orthopaedics and The Swedish Hip Arthroplasty Registry, Lund University, Skåne University Hospital, Malmö, Sweden; Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy and The Swedish Hip Arthroplasty Registry, University of Gothenburg, Sweden; Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy and The Swedish Hip Arthroplasty Registry, University of Gothenburg, Sweden; Finnish Arthroplasty Register, National Institute for Health and Welfare, Helsinki, Finland; Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technologies and Finnish Arthroplasty Register, University of Tampere, Tampere, Finland; Department of Orthopaedics and Traumatology and Finnish Arthroplasty Register, Turku University Hospital, Turku, Finland; Department of Surgical Sciences/Orthopaedics and The Swedish Hip Arthroplasty Registry, Uppsala University, Uppsala, Sweden
Background: Current literature indicates no difference in 90-day mortality after cemented compared with cementless THA. Although the individual burden of comorbidities is a very important confounder, very few studies were designed to address this issue.
Purpose / Aim of Study: We examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless total hip arthroplasty (THA) performed due to osteoarthritis.
Materials and Methods: Population-based, prospective cohort study based on The Nordic Arthroplasty Register Association database 2005-2013. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. We included 108,572 patients with cemented and 80,034 with cementless THA. Outcome: 90-day mortality. We used Cox regression to estimate hazard ratios (HR) with 95% confidence intervals comparing cemented with cementless THA, adjusting for age, gender, comorbidity, nation, and year of surgery.
Findings / Results: All-cause mortality within 90 days was 0.41% after cemented and 0.26% after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (0.79 to 1.20), and a similar risk estimate was obtained for mortality within 14 days. We found no differences in mortality between cemented and cementless THA after stratification by age, gender, Charlson comorbidity index, or year of surgery. However, among patients younger than 60 years, cemented THA was associated with a minimally increased adjusted mortality risk compared with cementless, with an absolute risk difference of 0.09%.
Conclusions: After adjustment for comorbidity as an important confounder, we observed no clinically relevant overall differences between the two fixation techniques in terms of early mortality. A small risk increase associated with cemented fixation in younger patients may be due to residual confounding and selection bias.
Department of Clinical Epidemiology, Aarhus University Hospital, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Denmark; Department of Surgical Sciences/Orthopaedics, Uppsala University, Sweden; Department of Orthopaedic Surgery and Traumatology and the Danish Hip Arthroplasty Register, Odense University Hospital, Denmark; The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Clinical Dentistry, University of Bergen, Bergen, Norway; The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway; Department of Orthopaedics and The Swedish Hip Arthroplasty Registry, Lund University, Skåne University Hospital, Malmö, Sweden; Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy and The Swedish Hip Arthroplasty Registry, University of Gothenburg, Sweden; Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy and The Swedish Hip Arthroplasty Registry, University of Gothenburg, Sweden; Finnish Arthroplasty Register, National Institute for Health and Welfare, Helsinki, Finland; Coxa Hospital for Joint Replacement, and Faculty of Medicine and Health Technologies and Finnish Arthroplasty Register, University of Tampere, Tampere, Finland; Department of Orthopaedics and Traumatology and Finnish Arthroplasty Register, Turku University Hospital, Turku, Finland; Department of Surgical Sciences/Orthopaedics and The Swedish Hip Arthroplasty Registry, Uppsala University, Uppsala, Sweden
Background: Current literature indicates no difference in 90-day mortality after cemented compared with cementless THA. Although the individual burden of comorbidities is a very important confounder, very few studies were designed to address this issue.
Purpose / Aim of Study: We examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless total hip arthroplasty (THA) performed due to osteoarthritis.
Materials and Methods: Population-based, prospective cohort study based on The Nordic Arthroplasty Register Association database 2005-2013. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. We included 108,572 patients with cemented and 80,034 with cementless THA. Outcome: 90-day mortality. We used Cox regression to estimate hazard ratios (HR) with 95% confidence intervals comparing cemented with cementless THA, adjusting for age, gender, comorbidity, nation, and year of surgery.
Findings / Results: All-cause mortality within 90 days was 0.41% after cemented and 0.26% after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (0.79 to 1.20), and a similar risk estimate was obtained for mortality within 14 days. We found no differences in mortality between cemented and cementless THA after stratification by age, gender, Charlson comorbidity index, or year of surgery. However, among patients younger than 60 years, cemented THA was associated with a minimally increased adjusted mortality risk compared with cementless, with an absolute risk difference of 0.09%.
Conclusions: After adjustment for comorbidity as an important confounder, we observed no clinically relevant overall differences between the two fixation techniques in terms of early mortality. A small risk increase associated with cemented fixation in younger patients may be due to residual confounding and selection bias.
Anders Falk Brekke, Søren Overgaard, Bo Mussmann, Erik Poulsen, Anders Holsgaard-Larsen
Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research - Center of Nutrition and Rehabilitation, Department of Physiotherapy, Odense University Hospital - University of Southern Denmark - University College Absalon, Region Zealand; Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research, Odense University Hospital - University of Southern Denmark; Department of Radiology - Department of Clinical Research - Faculty of Health Sciences, Odense University Hospital - University of Southern Denmark - Oslo Metropolitan University, Norway; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark; Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research, Odense University Hospital - University of Southern Denmark
Background: Patients with symptomatic acetabular retroversion is reported having reduced functional ability and quality of life but little is known about the effect of non-surgical interventions.
Purpose / Aim of Study: To investigate feasibility and change in patient-reported symptoms of a home-based exercise intervention in patients with acetabular retroversion and excessive anterior pelvic tilt, in comparison with a prior control period.
Materials and Methods: Patients with symptomatic acetabular retroversion and excessive anterior pelvic tilt were included. Following an 8-week control period, patients were instructed to follow an 8-week targeted (3 times/week) progressive home-based exercise intervention. Feasibility assessment included; dropout, acceptable adherence (≥75% of sessions), exercise-related pain, and adverse events. Primary outcome was change in the Copenhagen Hip and Groin Outcome Score (HAGOS) pain subscale. Secondary outcomes included change in the remaining HAGOS subscales, EQ-5D- 3L questionnaire, and pelvic tilt measured by EOS® scanning.
Findings / Results: Forty-two patients (39 women) (median [interquartile range (IQR)], 20.5 [19 - 25 years]) were included. Three patients were lost to follow-up (one regretting participating during the control period, one during the intervention period and one patient was lost at follow-up). Adherence to exercise sessions was 85%. Exercise- related pain and adverse events were acceptable. Between-period mean change score for the HAGOS-PAIN subscale was 5.2 points (95% confidence interval [CI]: [-0.3 – 10.6] and -1.6 degree [-3.9 – 0.7]) of anterior pelvic tilt. Additionally, patients who responded positively (≥ minimal clinically important difference) to the exercise intervention (n = 10, 26%), all had a pre-exercise HAGOS-PAIN score between 47.5 to 70 points.
Conclusions: Current exercise intervention was feasible. However, no clinical relevant changes in self- reported hip-related pain, function, quality of life, nor anterior pelvic tilt were found. Post- hoc responder analysis revealed that patients with moderate pain at baseline might benefit from current exercise.
Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research - Center of Nutrition and Rehabilitation, Department of Physiotherapy, Odense University Hospital - University of Southern Denmark - University College Absalon, Region Zealand; Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research, Odense University Hospital - University of Southern Denmark; Department of Radiology - Department of Clinical Research - Faculty of Health Sciences, Odense University Hospital - University of Southern Denmark - Oslo Metropolitan University, Norway; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark; Department of Orthopaedic Surgery and Traumatology - Department of Clinical Research, Odense University Hospital - University of Southern Denmark
Background: Patients with symptomatic acetabular retroversion is reported having reduced functional ability and quality of life but little is known about the effect of non-surgical interventions.
Purpose / Aim of Study: To investigate feasibility and change in patient-reported symptoms of a home-based exercise intervention in patients with acetabular retroversion and excessive anterior pelvic tilt, in comparison with a prior control period.
Materials and Methods: Patients with symptomatic acetabular retroversion and excessive anterior pelvic tilt were included. Following an 8-week control period, patients were instructed to follow an 8-week targeted (3 times/week) progressive home-based exercise intervention. Feasibility assessment included; dropout, acceptable adherence (≥75% of sessions), exercise-related pain, and adverse events. Primary outcome was change in the Copenhagen Hip and Groin Outcome Score (HAGOS) pain subscale. Secondary outcomes included change in the remaining HAGOS subscales, EQ-5D- 3L questionnaire, and pelvic tilt measured by EOS® scanning.
Findings / Results: Forty-two patients (39 women) (median [interquartile range (IQR)], 20.5 [19 - 25 years]) were included. Three patients were lost to follow-up (one regretting participating during the control period, one during the intervention period and one patient was lost at follow-up). Adherence to exercise sessions was 85%. Exercise- related pain and adverse events were acceptable. Between-period mean change score for the HAGOS-PAIN subscale was 5.2 points (95% confidence interval [CI]: [-0.3 – 10.6] and -1.6 degree [-3.9 – 0.7]) of anterior pelvic tilt. Additionally, patients who responded positively (≥ minimal clinically important difference) to the exercise intervention (n = 10, 26%), all had a pre-exercise HAGOS-PAIN score between 47.5 to 70 points.
Conclusions: Current exercise intervention was feasible. However, no clinical relevant changes in self- reported hip-related pain, function, quality of life, nor anterior pelvic tilt were found. Post- hoc responder analysis revealed that patients with moderate pain at baseline might benefit from current exercise.
Tobias Dahl Vind, Peter Bo Jørgensen, Dovydas Vainorius , Stig Storgaard Jakobsen, Kjeld Søballe, Maiken Stilling
Dept of Orthopaedics, Aarhus University Hospital; Department of Clinical Medicine, Aarhus University Hospital; University Clinic for Hand, Hip and Knee Surgery, Hospital Unit West; Dept of Orthopaedics, Aarhus University Hospital; Department of Orthopedics, Aarhus University Hospital; Hand Section, Dept of Orthopaedics, Aarhus University Hospital
Background: The Exeter short stem(ESS) is a 25 mm shorter stem compared to the classic v40 Exeter stem (Stryker) and is intended for use in a narrow femoral diaphysis.
Purpose / Aim of Study: To evaluate the migration pattern of the cemented Exeter short stem.
Materials and Methods: In a prospective single center cohort study, 23 patients (21 female) mean age 77.7 (range 70-89) with symptomatic hip osteoarthritis and Dorr Type A femurs were included. All were DXA scanned preoperatively (T-score/Bone Mineral Density (BMD)) and operated with a collarless polished double-tapered Exeter short stem type N°1 L125. Follow-up was performed at 6 weeks, 3, 6, 12 and 24 months with model- based RSA (stem migration), regular hip radiographs (stem position and cementation quality by Barrack’s system), Oxford Hip Score (OHS) and VAS pain. Mean (CI95%) are reported.
Findings / Results: The T-score was -1.4 (-1.8; -0.97). 7 patients had normal (> -1) and 15 low (<-1) T-score. At 2 years follow-up, the stems subsided 1.46 mm (1.67; 1.25) and retroverted 0.48 deg (-0.01; 0.97). From 12 to 24 months, stem subsidence was 0.18 mm (0.1; 0.25) (p=0.001) and retroversion -0.04 deg (-0.27; 0.18)(p=0.70). T-score and subsidence correlated moderately (Rho=0.48; p=0.025) and patients with normal T-score had 0.45 mm (0.05; 0.86) less subsidence as compared to patients with low T-score (p= 0.03). 13 stems were in neutral positions and 10 stems in varus (mean 4 deg, range 3.4; 5.8). Femoral component cementation quality was grade A in 15 patients, grade B in 7 patients, and grade C in 1 patient. Subsidence where similar in stems in neutral and varus position (p=0.069). Subsidence where similar between cementation quality groups (p=0.44) At 2-year follow-up, mean OHS improved (p<0.001) 18.5 points (13.5; 23.6) to 40.7 (36.8; 44.7), VAS pain at rest decreased (p<0.001) 22 mm (CI95 14; 32) to 5 mm (-1; 11), and VAS pain in activity decreased (p<0.001) 41 mm (27; 56) to 10 mm (2; 19).
Conclusions: The ESS migrated more in patients with low- as compared with normal T-score. The migration pattern of the cemented ESS is similar to reports for the cemented standard Exeter stem.
Dept of Orthopaedics, Aarhus University Hospital; Department of Clinical Medicine, Aarhus University Hospital; University Clinic for Hand, Hip and Knee Surgery, Hospital Unit West; Dept of Orthopaedics, Aarhus University Hospital; Department of Orthopedics, Aarhus University Hospital; Hand Section, Dept of Orthopaedics, Aarhus University Hospital
Background: The Exeter short stem(ESS) is a 25 mm shorter stem compared to the classic v40 Exeter stem (Stryker) and is intended for use in a narrow femoral diaphysis.
Purpose / Aim of Study: To evaluate the migration pattern of the cemented Exeter short stem.
Materials and Methods: In a prospective single center cohort study, 23 patients (21 female) mean age 77.7 (range 70-89) with symptomatic hip osteoarthritis and Dorr Type A femurs were included. All were DXA scanned preoperatively (T-score/Bone Mineral Density (BMD)) and operated with a collarless polished double-tapered Exeter short stem type N°1 L125. Follow-up was performed at 6 weeks, 3, 6, 12 and 24 months with model- based RSA (stem migration), regular hip radiographs (stem position and cementation quality by Barrack’s system), Oxford Hip Score (OHS) and VAS pain. Mean (CI95%) are reported.
Findings / Results: The T-score was -1.4 (-1.8; -0.97). 7 patients had normal (> -1) and 15 low (<-1) T-score. At 2 years follow-up, the stems subsided 1.46 mm (1.67; 1.25) and retroverted 0.48 deg (-0.01; 0.97). From 12 to 24 months, stem subsidence was 0.18 mm (0.1; 0.25) (p=0.001) and retroversion -0.04 deg (-0.27; 0.18)(p=0.70). T-score and subsidence correlated moderately (Rho=0.48; p=0.025) and patients with normal T-score had 0.45 mm (0.05; 0.86) less subsidence as compared to patients with low T-score (p= 0.03). 13 stems were in neutral positions and 10 stems in varus (mean 4 deg, range 3.4; 5.8). Femoral component cementation quality was grade A in 15 patients, grade B in 7 patients, and grade C in 1 patient. Subsidence where similar in stems in neutral and varus position (p=0.069). Subsidence where similar between cementation quality groups (p=0.44) At 2-year follow-up, mean OHS improved (p<0.001) 18.5 points (13.5; 23.6) to 40.7 (36.8; 44.7), VAS pain at rest decreased (p<0.001) 22 mm (CI95 14; 32) to 5 mm (-1; 11), and VAS pain in activity decreased (p<0.001) 41 mm (27; 56) to 10 mm (2; 19).
Conclusions: The ESS migrated more in patients with low- as compared with normal T-score. The migration pattern of the cemented ESS is similar to reports for the cemented standard Exeter stem.
Katrine Jessen Hvidt, Marianne Vestermark
Ortopedic department, Viborg Regional Hospital; Ortopedic department, Viborg Regional Hospital
Background: Dislocation is a well-known complication to total hip arthroplasty (THA) and constitutes a frequent cause of hospital contacts and revisions. The dual mobility cup (DMC) design has shown promising results in lowering the dislocation rate after primary THA compared to conventional cups. However, not many studies on long term dislocation rate of DMC in a large cohort are available. Viborg Regional Hospital introduced the DMC in 2001 (Saturne®, later Avantage™) and has since used it as primary acetabular component in THA’s in a variety of patients. Thus, a large cohort with the possibility of long-term follow-up is available.
Purpose / Aim of Study: To determine the dislocation rate of DMC (Saturne® and Avantage™) in primary THA’s with up to 10 years’ follow-up. Further, to elucidate factors that might effect the dislocation rate by subpopulation analysis.
Materials and Methods: The Danish Hip Arthroplasty Register (DHR) was used to identify THA’s with DMC inserted in Viborg since January 2001. 2721 cups in 2414 patients were identified for this study. Patients treated for dislocation of the DMC were retrospectively identified by review of medical files using several diagnosis-codes for identification. Information on each patient regarding indication of operation, means of fixation of the femoral stem and stem type was collected from DHR.
Findings / Results: We found a 2-year dislocation rate for DMC on 2,08% (95% CI 1,61-2,71%). The 10-year dislocation rate was 2,5% (95% CI 1,96-3,25%). The dislocation rate was lowest in patients who had a primary THA with DMC due to primary arthrosis and highest in patients treated for a displaced collum femoris fracture. Cemented stems (Exeter) had a lower dislocation rate compared to uncemented stems (Ancafit, Bicontact, Corail).
Conclusions: Our findings indicate a lower dislocation rate of DMC compared to conventional cups, especially in regards to long-term risk. The use of DMC seems particularly effective in lowering the dislocation rate in patients with collum femoris fractures. Means of fixation could affect the dislocation rate. However, further studies in regards to prosthesis survival of DMC are needed.
Ortopedic department, Viborg Regional Hospital; Ortopedic department, Viborg Regional Hospital
Background: Dislocation is a well-known complication to total hip arthroplasty (THA) and constitutes a frequent cause of hospital contacts and revisions. The dual mobility cup (DMC) design has shown promising results in lowering the dislocation rate after primary THA compared to conventional cups. However, not many studies on long term dislocation rate of DMC in a large cohort are available. Viborg Regional Hospital introduced the DMC in 2001 (Saturne®, later Avantage™) and has since used it as primary acetabular component in THA’s in a variety of patients. Thus, a large cohort with the possibility of long-term follow-up is available.
Purpose / Aim of Study: To determine the dislocation rate of DMC (Saturne® and Avantage™) in primary THA’s with up to 10 years’ follow-up. Further, to elucidate factors that might effect the dislocation rate by subpopulation analysis.
Materials and Methods: The Danish Hip Arthroplasty Register (DHR) was used to identify THA’s with DMC inserted in Viborg since January 2001. 2721 cups in 2414 patients were identified for this study. Patients treated for dislocation of the DMC were retrospectively identified by review of medical files using several diagnosis-codes for identification. Information on each patient regarding indication of operation, means of fixation of the femoral stem and stem type was collected from DHR.
Findings / Results: We found a 2-year dislocation rate for DMC on 2,08% (95% CI 1,61-2,71%). The 10-year dislocation rate was 2,5% (95% CI 1,96-3,25%). The dislocation rate was lowest in patients who had a primary THA with DMC due to primary arthrosis and highest in patients treated for a displaced collum femoris fracture. Cemented stems (Exeter) had a lower dislocation rate compared to uncemented stems (Ancafit, Bicontact, Corail).
Conclusions: Our findings indicate a lower dislocation rate of DMC compared to conventional cups, especially in regards to long-term risk. The use of DMC seems particularly effective in lowering the dislocation rate in patients with collum femoris fractures. Means of fixation could affect the dislocation rate. However, further studies in regards to prosthesis survival of DMC are needed.
Kristian Kjærgaard, Claus Varnum, Ming Ding, Søren Overgaard
Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthopaedic Surgery, Vejle Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: The main long-term revision cause of total hip arthroplasty (THA) is aseptic loosening which may be associated with polyethylene wear. Vitamin E doped polyethylene (VEPE) liners were designed to reduce wear and risk of aseptic loosening.
Purpose / Aim of Study: To investigate risk of revision of THA with VEPE liners compared to THA with cross-linked polyethylene (XLPE) liners in a nation-wide cohort.
Materials and Methods: We included uncemented THAs from The Danish Hip Arthroplasty Register performed between Jan 1, 2008 and Dec 31, 2017 with metal-on-polyethylene articulation and a VEPE or XLPE liner. Each THA was followed for at least one year. The primary outcome was revision for any cause, and secondarily revision for specific causes. Risk of revision with 95% confidence intervals was estimated using Cox regression adjusted for sex, age, comorbidity, duration of surgery (for infection) and head size (for dislocation).
Findings / Results: 3,472 (9%) THAs with a VEPE liner and 36,738 (91%) THAs with an XLPE liner were included. Median follow-up was 3.85 [interquartile range (IQR) 2.59, 5.04] years for VEPE liners and 4.34 [IQR 2.36, 6.78] years for XLPE liners (p<0.001). For early (≤ 90 days) revision, THA with VEPE had an increased risk of revision over XLPE (HR 1.77 [1.44, 2.16]), primarily due to increased risk of aseptic loosening of the stem (HR 10.67 [3.75, 30.37]) and femoral fracture (HR 2.34 [1.71, 3.19]). For risk of revision after 90 days, no difference was found in overall risk (HR 0.88 [0.69, 1.13]), but a lower risk of aseptic loosening for cup or stem was found for THA with VEPE liners (HR 0.50 [0.25, 0.96]). Early revision due to aseptic loosening or femoral fracture was associated with one particular stem (Bimetric collarless TI, odds-ratio 1.94 [1.36, 2.78]). No differences were found for risk of revision due to infection, dislocation, or other causes.
Conclusions: This is a nation-wide population-based study with complete follow-up of all THAs. THAs with a VEPE liner had an increased risk of early (≤ 90 days) revision compared with XLPE. Beyond 90 days, the risk of any revision was similar for THA with VEPE and XLPE liners, and interestingly, we found a lower risk of aseptic loosening for THA with VEPE liners.
Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthopaedic Surgery, Vejle Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: The main long-term revision cause of total hip arthroplasty (THA) is aseptic loosening which may be associated with polyethylene wear. Vitamin E doped polyethylene (VEPE) liners were designed to reduce wear and risk of aseptic loosening.
Purpose / Aim of Study: To investigate risk of revision of THA with VEPE liners compared to THA with cross-linked polyethylene (XLPE) liners in a nation-wide cohort.
Materials and Methods: We included uncemented THAs from The Danish Hip Arthroplasty Register performed between Jan 1, 2008 and Dec 31, 2017 with metal-on-polyethylene articulation and a VEPE or XLPE liner. Each THA was followed for at least one year. The primary outcome was revision for any cause, and secondarily revision for specific causes. Risk of revision with 95% confidence intervals was estimated using Cox regression adjusted for sex, age, comorbidity, duration of surgery (for infection) and head size (for dislocation).
Findings / Results: 3,472 (9%) THAs with a VEPE liner and 36,738 (91%) THAs with an XLPE liner were included. Median follow-up was 3.85 [interquartile range (IQR) 2.59, 5.04] years for VEPE liners and 4.34 [IQR 2.36, 6.78] years for XLPE liners (p<0.001). For early (≤ 90 days) revision, THA with VEPE had an increased risk of revision over XLPE (HR 1.77 [1.44, 2.16]), primarily due to increased risk of aseptic loosening of the stem (HR 10.67 [3.75, 30.37]) and femoral fracture (HR 2.34 [1.71, 3.19]). For risk of revision after 90 days, no difference was found in overall risk (HR 0.88 [0.69, 1.13]), but a lower risk of aseptic loosening for cup or stem was found for THA with VEPE liners (HR 0.50 [0.25, 0.96]). Early revision due to aseptic loosening or femoral fracture was associated with one particular stem (Bimetric collarless TI, odds-ratio 1.94 [1.36, 2.78]). No differences were found for risk of revision due to infection, dislocation, or other causes.
Conclusions: This is a nation-wide population-based study with complete follow-up of all THAs. THAs with a VEPE liner had an increased risk of early (≤ 90 days) revision compared with XLPE. Beyond 90 days, the risk of any revision was similar for THA with VEPE and XLPE liners, and interestingly, we found a lower risk of aseptic loosening for THA with VEPE liners.
Lina Holm Ingelsrud, Kirill Gromov, Christian Skovgaard Nielsen, Søren Overgaard, Anders Troelsen
Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery and Traumatology; Department of Clinical Research, Odense University Hospital; University of Southern Denmark; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: Meaningful interpretation of improvements in Oxford Hip Score (OHS) is challenged by the lack of knowledge about the patients’ perspectives on which degree of improvement that reflects important change.
Purpose / Aim of Study: To determine Minimal Important Change (MIC) values for the OHS in patients undergoing primary total hip replacement (THR).
Materials and Methods: Data from patients undergoing primary THR due to primary hip osteoarthritis between January 2015 and March 2019 were extracted from one hospital’s arthroplasty database. Patients completed the OHS preoperatively and at 12 months postoperatively, accompanied by an MIC anchor question. Response options were 1) better, an important improvement, 2) somewhat better, but enough to be an important improvement, 3) very small change, not enough to be an important improvement, 4) about the same, 5) very small change, not enough to be an important deterioration, 6) somewhat worse, but enough to be an important deterioration, and 7) worse, an important deterioration. MIC values were defined with the predictive modeling approach based on logistic regression, with important improvement (responses 1 or 2) as dependent variable and change in OHS as independent variable. The MIC was adjusted for the high proportion of improved patients. Confidence Intervals (CI) were derived with bootstrapping.
Findings / Results: Complete data were obtained for 393 out of 627 (63%) patients with available data undergoing primary THR due to hip OA (median age 70 years, 57% female). The proportion of patients reporting having improved importantly after 12 months was 96% (n=377), while 4% (n=13) reported being unchanged or worse. Spearman’s correlation between the anchor and the OHS change score was 0.38. The OHS MIC value (95% CI) was 7.4 (4.8; 9.6).
Conclusions: We established an improvement at 1-year follow-up of 8 OHS points to represent the MIC value after THR. The estimate serves as a good starting point for interpretation of PROM outcomes collected in national quality databases. A large number of patients are needed to calculate robust MIC values. Considering the low number of not importantly improved patients, the MIC value should be confirmed in larger and national cohorts.
Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic Surgery and Traumatology; Department of Clinical Research, Odense University Hospital; University of Southern Denmark; Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre
Background: Meaningful interpretation of improvements in Oxford Hip Score (OHS) is challenged by the lack of knowledge about the patients’ perspectives on which degree of improvement that reflects important change.
Purpose / Aim of Study: To determine Minimal Important Change (MIC) values for the OHS in patients undergoing primary total hip replacement (THR).
Materials and Methods: Data from patients undergoing primary THR due to primary hip osteoarthritis between January 2015 and March 2019 were extracted from one hospital’s arthroplasty database. Patients completed the OHS preoperatively and at 12 months postoperatively, accompanied by an MIC anchor question. Response options were 1) better, an important improvement, 2) somewhat better, but enough to be an important improvement, 3) very small change, not enough to be an important improvement, 4) about the same, 5) very small change, not enough to be an important deterioration, 6) somewhat worse, but enough to be an important deterioration, and 7) worse, an important deterioration. MIC values were defined with the predictive modeling approach based on logistic regression, with important improvement (responses 1 or 2) as dependent variable and change in OHS as independent variable. The MIC was adjusted for the high proportion of improved patients. Confidence Intervals (CI) were derived with bootstrapping.
Findings / Results: Complete data were obtained for 393 out of 627 (63%) patients with available data undergoing primary THR due to hip OA (median age 70 years, 57% female). The proportion of patients reporting having improved importantly after 12 months was 96% (n=377), while 4% (n=13) reported being unchanged or worse. Spearman’s correlation between the anchor and the OHS change score was 0.38. The OHS MIC value (95% CI) was 7.4 (4.8; 9.6).
Conclusions: We established an improvement at 1-year follow-up of 8 OHS points to represent the MIC value after THR. The estimate serves as a good starting point for interpretation of PROM outcomes collected in national quality databases. A large number of patients are needed to calculate robust MIC values. Considering the low number of not importantly improved patients, the MIC value should be confirmed in larger and national cohorts.
Philip Nielsen, Claus Varnum, Søren Overgaard
RKKP, the Danish Hip Arthroplasty Register, Region Midtjylland; Department of Orthopaedic Surgery, Vejle Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: In elderly patients, there is good evidence that cemented femoral components have a good long- term track record, whereas there is a higher degree of uncertainty for cemented acetabular components. During recent years there has been a trend towards a decreased use of cemented cups.
Purpose / Aim of Study: We aimed to evaluate the risk of revision due to any cause after insertion of cemented or cementless cups and a cemented stem in patients aged 70 years or older diagnosed with osteoarthritis, and secondly to estimate the risk of acetabular revision (cup, liner and/or head) due to any cause in the two groups.
Materials and Methods: In the Danish Hip Arthroplasty Register, we identified all primary total hip arthroplasties (THAs) with a cemented stem operated from January 1, 2002 to December 31, 2018 in patients aged 70 years or older with a cemented (N=16,255) or cementless (N=13,227) cup. The Kaplan-Meier estimator was used to assess the component survival, and Cox regression was used to estimate the adjusted relative risk (aRR) of revision both assessed with 95% confidence intervals. Adjustments were made for age, sex, bearing surface (metal-on-polyethylene, ceramic- on-polyethylene) and comorbidity.
Findings / Results: All revisions: The 15-year survivorship was 93 % (92.2 - 93.6) for revision of cemented THAs and 91 % (89.7 – 91.9) for revision of hybrid THA. After 15 years 717 and 583 revisions were performed for cemented THA and hybrid THA, respectively. The aRR for any revision showed a decreased risk for cemented (0.85 (0.75-0.95)) compared to hybrid THA. Acetabular revisions: The 15-year survivorship was 96 % (95.7 - 96.7) for cemented and 96 % (95.4 – 97.0) for cementless cups. After 15 years, 408 cemented and 292 cementless acetabular revisions were performed for any reason. THAs with a cemented cup had similar aRR of acetabular revision (1.03 (0.88-1.22)) compared to those with cementless.
Conclusions: In patients having THAs, we found a decreased risk of revision of cemented compared with hybrid THA due to any cause. When restricting the analysis to revisions with cup replacement, we found no difference between cemented and cementless cups.
RKKP, the Danish Hip Arthroplasty Register, Region Midtjylland; Department of Orthopaedic Surgery, Vejle Hospital; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: In elderly patients, there is good evidence that cemented femoral components have a good long- term track record, whereas there is a higher degree of uncertainty for cemented acetabular components. During recent years there has been a trend towards a decreased use of cemented cups.
Purpose / Aim of Study: We aimed to evaluate the risk of revision due to any cause after insertion of cemented or cementless cups and a cemented stem in patients aged 70 years or older diagnosed with osteoarthritis, and secondly to estimate the risk of acetabular revision (cup, liner and/or head) due to any cause in the two groups.
Materials and Methods: In the Danish Hip Arthroplasty Register, we identified all primary total hip arthroplasties (THAs) with a cemented stem operated from January 1, 2002 to December 31, 2018 in patients aged 70 years or older with a cemented (N=16,255) or cementless (N=13,227) cup. The Kaplan-Meier estimator was used to assess the component survival, and Cox regression was used to estimate the adjusted relative risk (aRR) of revision both assessed with 95% confidence intervals. Adjustments were made for age, sex, bearing surface (metal-on-polyethylene, ceramic- on-polyethylene) and comorbidity.
Findings / Results: All revisions: The 15-year survivorship was 93 % (92.2 - 93.6) for revision of cemented THAs and 91 % (89.7 – 91.9) for revision of hybrid THA. After 15 years 717 and 583 revisions were performed for cemented THA and hybrid THA, respectively. The aRR for any revision showed a decreased risk for cemented (0.85 (0.75-0.95)) compared to hybrid THA. Acetabular revisions: The 15-year survivorship was 96 % (95.7 - 96.7) for cemented and 96 % (95.4 – 97.0) for cementless cups. After 15 years, 408 cemented and 292 cementless acetabular revisions were performed for any reason. THAs with a cemented cup had similar aRR of acetabular revision (1.03 (0.88-1.22)) compared to those with cementless.
Conclusions: In patients having THAs, we found a decreased risk of revision of cemented compared with hybrid THA due to any cause. When restricting the analysis to revisions with cup replacement, we found no difference between cemented and cementless cups.