Session 12: Knee II

Fredag d. 26. oktober
09:00-10:30
Lokale: Reykjavik
Chairmen: Anders Troelsen og Svend Erik Østgaard

86. Postoperative phone calls (Coaching to Self-Care model) after total knee arthroplasty surgery do not alter patient-reported outcome measures
Robin Bawer, Anne Mørup-Petersen, Anne-Katrine Mathiassen, Britta Hørdam, Anders Odgaard
Department of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte; Department of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte; Department of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte; Department of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte; Department of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte


Background: Follow-up regimes after total knee arthroplasty (TKA) are in constant change. Coaching to Self-Care (CtSC) is a telephonic follow-up model for counselling patients, and it has shown beneficial effects on patient-reported outcome measures (PROMs) during rehabilitation after total hip arthroplasty. We hypothesized that similar effects could be seen after TKA. Such effects could herald a change from clinical follow-up to CtSC.
Purpose / Aim of Study: To evaluate the effect of CtSC on knee- specific and generic PROMs in TKA patients by comparing with a control group.
Materials and Methods: CtSC is based on questions regarding general and knee-specific well-being, and individualized counseling for patients. Patients operated on Mondays and Tuesdays in the period from 25/10/16 to 31/1/17 received telephone calls by a nurse 1, 3 and 7 weeks after TKA and thus followed using the CtSC principles (intervention group, n = 98). Patients operated on Wednesdays and Thursdays during the same period did not receive any calls (control group, n = 77). Both groups were evaluated at baseline, at 6 weeks and 3, 6 and 12 months postoperatively with patient-reported parameters: Oxford Knee Score (OKS, 0-48), patient satisfaction, range of motion, consumption of analgetics and EQ-5D-5L.
Findings / Results: PROMs were available for 62 and 77 patients in the intervention and control group, respectively. Mean OKS values at baseline were 23.2 (SD 5.9) and 22.7 (SD 6.7), P = 0.62. At 6 weeks, the OKS values were 27.5 (SD 6.4) and 26.2 (SD 7.0), P = 0.40. On all aforementioned parameters we found no significant difference between the groups during the 1-year follow-up period.
Conclusions: Based on this study CtSC has no effect on knee specific and generic PROMs after TKA. Further studies may determine if there are subgroups of patients who could benefit from the intervention.

87. Can regional differences in revision rates after knee arthroplasty surgery be explained by differences in symptom states prior to primary surgery? Preoperative results from the "SPARK" study.
Anne Mørup-Petersen, Mogens Berg Laursen, Frank Madsen, Michael Rindom Krogsgaard, Anders Odgaard
Department of Orthopaedic Surgery, Copenhagen University Hospital, Herlev-Gentofte; Department of Orthopaedic Surgery, Aalborg University Hospital Farsø; Department of Orthopaedic Surgery, Århus University Hospital; Department of Orthopaedic Surgery, Copenhagen University Hospital Bispebjerg; Department of Orthopaedic Surgery, Copenhagen University Hospital, Herlev-Gentofte


Background: The risk of revision after knee arthroplasty (KA) varies greatly between Danish regions. We are not sure what this means to patients. Though revision is an important outcome, surgical quality might also be evaluated by viewing data on all KA patients instead of only those undergoing subsequent revision. The prospective observational “SPARK” study was performed to compare KA patients across regions using uniform PROM sets pre- and postoperatively.
Purpose / Aim of Study: This part of the study aims to describe whether patients awaiting primary KA differ between large hospitals in each of three regions that are traditionally known to differ in revision rates (1.0 to 5.0% per 2 y., 2015).
Materials and Methods: From 1 Sept 2016 and 14-16 months ahead all patients scheduled for medial unicompartmental (mUKA) or total knee arthroplasty (TKA) in three hospitals were invited to answer a set of PROMs, either electronically or on paper. Knee specific PROMs such as Oxford Knee Score (OKS 0-48) and Copenhagen Knee ROM Scale were obtained along with generic and qualitative questions.
Findings / Results: Preoperative PROMs were completed by 1329 patients (Farsø 207, Århus 304 and Gentofte 818 patients). OKS was higher, indicating less severe symptoms, prior to mUKA compared to TKA (24.3 vs. 22.9, P=0.0016). No difference in OKS was found between patients scheduled for the same procedure in different regions. The same pattern applies for patient-reported range of motion (P < 0.001).
Conclusions: Based on PROMs from three hospitals, we find no reason to believe that patients differ in symptom states prior to primary KA between Danish regions. However, works continue to explore demographic, lifestyle and qualitative data, and a comparison of radiographic signs of knee osteoarthritis may uncover whether perception of symptoms varies between regions.

88. Discriminating between mild and severe radiographic knee osteoarthritis using a performance test and gait summary measures – A cross-sectional study
Josefine Eriksson Naili, Eva Weidenhielm Broström, Ewa M. Roos, Brian Clausen, Anders Holsgaard-Larsen
Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Research Unit for Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Research Unit for Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark


Background: Little is known about which tests of knee function that may discriminate between mild and severe knee osteoarthritis (OA).
Purpose / Aim of Study: This cross-sectional study evaluated whether a physical performance-based test and summary measures of overall gait function by 3D gait analysis could discriminate between patients with mild and severe radiographic OA in a case-mix of individuals with knee OA.
Materials and Methods: The study sample (n=115) consisted of 60% women, with a mean age of 61 years (SD 8) and mean BMI of 27 (SD 5). All participants performed the maximal 30-second Single Limb Mini Squat test (SLMS), and underwent 3D gait analysis. Radiographic severity was classified using Kellgren and Lawrence (KL) classification ranging between grades 0-4. The Gait Deviation Index (the pathologic deviation from a healthy reference group) for kinematics (GDI) and kinetics (GDI-kinetic) were subsequently calculated and used to summarize ‘gait quality’ into a single score. Area under receiver operating characteristic curves (AUC) and 95% confidence intervals (CI) were used to evaluate whether SLMS and GDI-scores could discriminate between patients with mild (KL grade 1 and 2) and severe (KL grade 3 and 4) knee OA.
Findings / Results: Performance on the SLMS test displayed a good ability to classify individuals into either mild or severe knee OA (AUC 0.83, CI 0.76 – 0.91). The ability of GDI to discriminate OA severity was moderate (AUC 0.62, CI 0.52 – 0.73), and GDI- kinetics poor (AUC 0.36, CI 0.26 – 0.47).
Conclusions: The SLMS test is able to discriminate between patients with mild and severe radiographic knee OA, and is a useful physical performance-based test easily used in clinical practice. Gait summary measures are not able to discriminate radiographic severity in the present case-mix of individuals with knee OA.

89. Is the postoperative Forgotten Joint Score associated with the preoperative score in patients undergoing total knee arthroplasty?
Sofie Ryaa, Lina H. Ingelsrud, Håkon Sandholdt, Kirill Gromov, Henrik Husted, 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, Copenhagen University Hospital Hvidovre; Department of Orthopaedic surgery, Copenhagen University Hospital Hvidovre; Department of Orthopaedic surgery, Copenhagen University Hospital Hvidovre


Background: It is not clear whether the preoperative level of knee awareness as measured with the Forgotten Joint Score (FJS) impacts on the likelihood of gaining low knee awareness after total knee arthroplasty (TKA).
Purpose / Aim of Study: To evaluate the association between preoperative FJS and the postoperative FJS at one-year follow-up in patients receiving primary TKA.
Materials and Methods: All patients undergoing primary TKA registered in a local TKA registry from 01.01.2015 to 01.03.2017 were included. Age, gender and Body Mass Index (BMI) were recorded preoperatively. The FJS pre- and one year postoperatively was used for analysis (0-100, worst-best). Oxford Knee Score (OKS) was used to describe the patients’ pain- and functional level (0-48, worst-best). Multiple linear regression analysis was used to study the association between post- (dependent variable) and preoperative FJS as well as the possible confounding effect of age, gender and BMI (independent variables).
Findings / Results: Out of 735 eligible patients, 574 (78%) patients responded to the FJS and OKS at one year follow-up. Responders had a median (25;75 quantile) age of 68.8 (61.5;74.1) years and 60.1% were female. Median (25;75 quantile) preoperative FJS and OKS were 12.5 (5.0;25.0) and 22.0 (17.0;27.0), respectively. Multiple regression analysis showed significant association between pre- and postoperative FJS, with an estimate of 0.4 (p<0.001) and adjusted R2 of 0.097, when adjusting for age, gender and BMI.
Conclusions: The study found a clinical small, but significant association between preoperative FJS and one year postoperative FJS, suggesting that patients with low levels of knee awareness preoperatively are more likely to be less aware of their knee joint one year after TKA. Ensuring the predictive ability of the preoperative FJS requires external validation in another cohort.

90. Take good care of your menisci; once build, they don’t renew
Christoffer Våben, Katja Heinemeier, Peter Schjerling, Michael Mørk Petersen, Michael Kjær, Michael Krogsgaard
Section for Sports Traumatology M51, Department of Orthopaedic Surgery M, Bispebjerg-Frederiksberg Hospital; Institute of Sports Medicine, Department of Orthopaedic Surgery M,, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen; Institute of Sports Medicine, Department of Orthopaedic Surgery M,, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen; Musculoskeletal Tumor Section, Department of Orthopaedic Surgery, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen; Institute of Sports Medicine, Department of Orthopaedic Surgery M,, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen; Section for Sports Traumatology M51, Department of Orthopaedic Surgery M, Bispebjerg-Frederiksberg Hospital


Background: The meniscus is essential for weight distribution in the knee joint and preservation of joint cartilage. The architectural structure of meniscal collagen is the basis for its weight absorbing properties. Injury and degeneration of menisci are the most common symptomatic conditions of the knee, and their treatment has been subject to debate during the recent years. The content of water and glycosaminoglycans (GAG) in menisci adapts through life, but can collagen renew to reduce meniscal degeneration and support repair after meniscal injury?
Purpose / Aim of Study: This study explores the collagen turnover in both healthy and osteoarthritis (OA) menisci by the “14C bomb-pulse method”. Secondarily, water-, GAG-, and collagen content was measured.
Materials and Methods: Menisci from 18 patients with osteoarthritis (OA) and 7 patients with normal knees born before, during and after the bomb-pulse peak, went through a collagen purification process and were analyzed for 14C-content. Furthermore, the water-, GAG-, and collagen content was analyzed in raw menisci.
Findings / Results: We demonstrated a very low turnover of the collagen in menisci after they had matured during teen-age in knees with osteoarthritis as well as in and healthy knees. There was no difference between medial and lateral meniscus or between the central and the capsular part of the menisci. There was no difference in water content between menisci from healthy and OA knees, but a higher GAG content in OA menisci and an insignificant trend of lower collagen content in OA menisci.
Conclusions: We conclude that human menisci have practically no potential to repair or renew the natural collagen meshwork once the menisci have matured at teen- age. Prevention of degeneration and injury is therefore essential in research on how to reduce the burden of meniscal disease.

91. Increased TTTG measured on axial MRI is not due to lateralization of the tibial tubercle but medialization of the trochlear groove. A cross sectional study of dysplastic and non-dysplastic knees.
Mathias Paiva, Lars Blønd, Kristoffer Weisskirchner Barfod
Sports Orthopedic Research Center Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre.; Department of Orthopedic Surgery, Zealand University Hospital, Køge and Aleris-Hamlet Parken; Sports Orthopedic Research Center Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre.


Background: .
Purpose / Aim of Study: To investigate if increased Tibial tubercle – Trochlear Groove distance (TT-TG) measured on axial MRI is due to lateralization of the tibial tubercle or medialization of the trochlear groove.
Materials and Methods: The study was performed as a cross sectional study of 67 knees (29 normal, 26 with trochlear dysplasia (TD) and 12 with patellar dislocation without TD). MRI data was gathered from October 2010 to December 2017 at Køge Hospital and Parken Private hospital. The medial border of the posterior cruciate ligament (PCL) was chosen as the central anatomical landmark. The distance from the tibial tubercle (TT) to PCL (TT-PCL) was measured to examine the lateralization of the tibial tubercle. The distance from the trochlear groove to PCL (TG-PCL) was measured to examine the medialization of the trochlear groove. Between group differences was investigated by use of one-way ANOVA.
Findings / Results: The mean (SD) values for TT-TG were 8.5 mm (3.6) in the normal group, 11.4 mm (6.2) in the group with patellar dislocation without TD and 17.1 mm (4.8) in the TD group (p<0.01). The mean (SD) values for TT-PCL were 19.5 mm (4.2) in the normal group, 17.0 mm (5.0) in the group with patellar dislocation without TD and 20.2 mm (5.0) in the TD group (p= 0.10). The mean (SD) values for TG-PCL were 10.5 mm (3.7) in the normal group, 5.8 mm (4.9) in the patellar dislocation group without TD and 3.9 mm (3.9) in the dysplastic group (p<0.01).
Conclusions: TD knees had increased TT-TG compared to normal knees and knees with patellar dislocation without TD. The TT-PCL distance did not differ significantly between groups, whereas the TG-PCL distance declined with increased TT-TG. The present results indicate that increased TT-TG is due to medialization of the trochlear groove and not lateralization of the tibial tubercle.

92. RELIABILITY OF STRESS RADIOGRAPHY IN QUANTIFICATION OF CORONAL LAXITY FOLLOWING TOTAL KNEE ARTHROPLASTY.
Andreas Kappel, Nielsen Poul Torben, Odgaard Anders, Laursen Mogens
Aalborg/Farsø, Aalborg University Hospital; Aalborg/Farsø, Aalborg University Hospital; Gentofte, Copenhagen University; Aalborg/Farsø, Aalborg University Hospital


Background: Instability is one of the main causes for early failure following total knee arthroplasty (TKA), and the frequency of revisions due to instability is rising in both national and international registries. The reliability of clinical soft tissue laxity examination is proven unsatisfactory and may be biased by patient complaints. Soft tissue laxity can be quantified with stress radiography, where the degree of stability between the components is measured as an angulation.
Purpose / Aim of Study: To examine the reliability of coronal stress radiography following TKA.
Materials and Methods: 17 cases with uncomplicated TKA were examined with coronal stress radiograph under both varus- and valgus-stress. In extension, the Telos device was applied. In flexion, the epicondylar view with a horizontal stress was used. All procedures were repeated (test/re-test).
Findings / Results: Mean laxity and SD were comparable to values published earlier. Pearson correlation coefficient, mean and SD for the differences in angulation between the repeated radiographs were as follows. Extension and valgus stress, cc=.97, mean .140, SD .620. Extension and varus stress, cc=.97, mean .180, SD .530. Flexion and valgus stress, cc=.95, mean .20, SD .820. Flexion and varus stress, cc=.77, mean .340, SD 2.90. In flexion and varus stress the angulations measured was larger and both rotation and translation between the components became evident on the stress radiographs.
Conclusions: Coronal stress radiography is a reliable method to judge soft tissue laxity following TKA. The method is clinically applicable and may be a useful tool in both postoperative evaluation and in research.

93. Debridement and exchange of tibial insert of the infected knee arthroplasty
Morten Torrild Schmiegelow, Frederik Taylor Pitter, Jens Bagger, Anders Odgaard, Martin Lindberg-Larsen
Department of Orthopedic surgery, Copenhagen University Hospital Bispebjerg; Department of Orthopedic surgery, Copenhagen University Hospital Rigshospitalet; Department of Orthopedic surgery, Copenhagen University Hospital Bispebjerg; Department of Orthopedic surgery, Copenhagen University Hospital Gentofte; Department of Orthopedic surgery, Odense University Hospital


Background: Surgical treatment of periprosthetic knee infection is debridement with exchange of the tibial insert or a one- or two-stage exchange arthroplasty procedure. Implant salvage using the less comprehensive debridement procedure is appealing, but high failure rates have been reported.
Purpose / Aim of Study: To study the re-revision rate due to infection after first-time debridements and debridements of previously revised knee arthroplasties (KA). And, to investigate the association between time-course from previous KA to the debridement and risk of re-revision due to infection.
Materials and Methods: Data on all debridements performed under the indication periprosthetic knee infection and later re-revisions due to infection from 2007-2017 were collected from The Danish Knee Arthroplasty Register.
Findings / Results: A total of 416 debridements; 297 first- time revisions and 119 revisions of previously revised KAs were registered. The re-revision rate after first-time debridements was 31% (95% CI 23.2-38.8). 48.8% of these were performed within 0-30 days, 19.5% within 31-90 days, 7.7% within 91-365 days and 23.9% >365 days after the previous primary KA and re-revision rates were 34.5%, 31.0%, 30.4% and 23.9% respectively (p=0.5). The re- revision rate of partial revisions of previously revised knee arthroplasties was 51.3% (95% CI 42.5-60.1). 42% of these were performed within 0-30 days, 10.9% within 31-90 days, 19.3% within 91-365 days and 27.7% >365 days after the previous KA and re- revision rates were 44.0%, 53.8%, 73.9% and 45.5% respectively (p=0.1).
Conclusions: We found a re-revison rate of 31% after the first-time debridements and 51% after debridement of previously revised KA. Surprisingly more than half of the debridements were performed >30 days after previous KA and we found no association between time from previous KA and risk of re-revision.

94. Safe Performance of Vitamin E-Infused Polyethylene in TKA at Three Year Follow-up Evaluated in a Prospective, Multicenter Study
Christian Nielsen, James W. Connelly, Vincent P. Galea,, Mina A. Botros, James I. Huddleston , Henrik Malchau, Anders Troelsen
Department of Orthopedics , Copenhagen University Hospital, Hvidovre, Denmark ; The Harris Orthopaedic Laboratory, Orthopaedic Department,, Massachusetts General Hospital, Boston, USA; The Harris Orthopaedic Laboratory, Orthopaedic Department,, Massachusetts General Hospital, Boston, USA; The Harris Orthopaedic Laboratory, Orthopaedic Department,, Massachusetts General Hospital, Boston, USA; Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford, California, USA; Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Orthopaedic surgery, , Copenhagen University Hospital Hvidovre, Copenhagen, Denmark


Background: Vitamin E-infused polyethylene has shown low wear for THA but literature confirming the safety and efficacy of vitamin E-infused polyethylene in Total Knee Arthroplasty (TKA) in a clinical setting is extremely limited
Purpose / Aim of Study: The aim of this prospective multicenter study was to investigate the safety and efficacy of vitamin E- infused polyethylene in TKA after 3 years as assessed by 1) rate of revision (2) risk of developing osteolytic lesions 3) functionality (PROMs)
Materials and Methods: A total of 391 TKA patients from 8 centers in 4 continents (Europa, North America, Asia and Australia) received were included in the study and operated fra 2011 to 2014. All TKA devices in the study were cemented and utilized vitamin E liners. The present analysis reports on patient demographic data, as well as radiographic assessment and PROMs collected at the 3-year interval (2.5 - 4.5 years).
Findings / Results: Three patients were revised, 2 due to acute sepsis and 1 due to aseptic loosening 1,5 y postoperatively, with a cumulative survival rate of 99.2%. Of those eligible for follow-up, 299 (80.8%) reported 3-year PROMs and 302 (81.6%) received 3-year postoperative radiographs. Radiographic analysis showed that 264 (87.4%) patients had no signs of radiolucent lines. There were no cases of osteolysis at 3-years. PROM values: KOOS (Pain, Symptoms, Activities in Daily Life, Sports/Recreation, Quality of Life), UCLA and EQ-5D all showed significant improvements from the preoperative baseline. (p < 0.001)
Conclusions: In this multicenter study, vitamin E-infused polyethylene was associated with a low rate of postoperative complications and low osteolytic potential at 3-year follow-up based on low revision rates and radiographic findings. Functionality, symptoms and quality of life PROMs were excellent at three years across the study cohort

95. Day of surgery discharge in patients undergoing unicompartmental knee replacement. A prospective cohort-study in an unselected patient group
Søren Rytter, Bjørn Gottlieb Jensen, Stig Munk, Susanne Jung, Torben Bæk Hansen
University Clinic for Hand, Hip and Knee Surgery, Regional Hospital Holstebro, Denmark; Department of Orthopedic Surgery, Lillebælt Hospital, Regional Hospital of Vejle, Denmark ; University Clinic for Hand, Hip and Knee Surgery, Regional Hospital Holstebro, Denmark; Department of Orthopedic Surgery, Lillebælt Hospital, Regional Hospital of Vejle, Denmark ; University Clinic for Hand, Hip and Knee Surgery and The Lundbeck Foundation Centre for Fast-Track Hip and Knee arthroplasty Denmark, Regional Hospital of Hostebro, Denmark


Background: With an improved multimodal pain treatment there have been an increased focus on fast track programmes and the potential to convert unicompartmental knee replacement (UKR) surgery from short-admission surgery to ambulatory surgery with same-day discharge.
Purpose / Aim of Study: The purpose of this study was to describe patient selection and completion rates in an unselected patient group undergoing UKR at two different high volume hospitals.
Materials and Methods: All consecutive patients (n = 368) referred to and selected for a medial UKR at two participating clinics were screened for eligibility for outpatient surgery with discharge to their own home on the day of surgery (DOS). Reasons for not being discharged on the DOS were recorded in patients not fulfilling the outpatient pathway and complications (infection and reoperation) and readmission were recorded until 4 months postoperatively.
Findings / Results: 96% (n = 255) of all referred and screened patients in this unselected healthcare population for UKR were eligible for outpatient surgery. DOS discharge occurred in 59 % of the operated patients and 36 % of all referred and screened patients. Main reasons for not being discharged were active wound drainage, postoperative nausea and vomiting and dizziness or malaise. Two patients were readmitted during the first 24 hours due to bleeding. There were no infections. One patient had a lung embolus and one patient an AMI in the period 0-90 days after surgery. 93% of the patients would undergo outpatient surgery again.
Conclusions: This study illustrates that not all patients in an unselected healthcare population for UKR were suitable for outpatient surgery as only 36 % of all referred and screened patients were discharged on the DOS. Further studies should focus on optimizing pain treatment and especially reducing postoperative nausea.