Session 7: Knee I

Torsdag den 25. oktober
09:30-10:30
Lokale: Sweden
Chairmen: Andreas Kappel og Christian Skovgaard

42. What is the Outcome of Bi-cruciate Versus Cruciate Retaining Total Knee Arthroplasty at 2-year Follow-up Assessed in a Randomized Controlled Trial?
Anders Troelsen, Lina Holm Ingelsrud, Morten Grove Thomsen, Omar Muharemovic, Kristian Otte, Henrik Husted
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 Radiology, Copenhagen University Hospital Hvidovre; Department of orthopaedic surgery, Copenhagen University Hospital Hvidovre; Department of orthopaedic surgery, Copenhagen University Hospital Hvidovre


Background: Bi-cruciate retaining (Bi-CR) total knee arthroplasty (TKA) intend to improve outcome by maintaining intrinsic ACL functions.
Purpose / Aim of Study: The aim was to compare tibial implant migration and clinical outcomes of Bi- CR and CR TKA.
Materials and Methods: This single-blinded parallel-group trial randomized 50 patients eligible for a CR TKA with intact ACL during surgery to receive a Bi-CR or CR TKA. Patients suspected to have ACL rupture were excluded. The primary outcome was the maximum total point motion (MTPM) measured with radiostereometric analyses at 2 years postoperatively. Patient-reported outcomes were assessed by the Oxford Knee Score (OKS; 0-48) and the Forgotten Joint Score (FJS; 0-100).
Findings / Results: At 2 years postoperatively, RSA images were available for 45 patients and PROMs for 48 patients. The mean MTPM was 0.59 and 0.62 mm in the Bi- CR and CR groups, respectively (p=0.82). Two patients (2-year OKS: 41 and 43) receiving Bi-CR TKA were classified as migration outliers. The improvement in median OKS from preoperative to 2 years was 20.5 to 41.0 and 25.0 to 44.0 in the Bi-CR and CR groups, respectively. The mean FJS improved from 16.1 to 62.0 and 21.8 to 69.6 in the Bi-CR and CR groups, respectively. Neither absolute values at 2 years nor improvements showed statistically significant differences between the groups (p=0.07 and 0.96 for OKS; p=0.28 and 0.80 for FJS, respectively). Three patients (Bi-CR group) underwent arthroscopically assisted manipulation between 3 and 4 months postoperatively. One patient sustained a tibial island fracture during primary surgery and was revised after 6 months.
Conclusions: Stable fixation and excellent clinical outcomes of a Bi-CR TKA at 2 year follow-up, similar to a gold standard CR TKA, can be achieved, although a unique learning curve was identified.

43. 6-year Radiosteriometric Follow-up on a RCT with Comparison of the Vanguard Tibial Component with either Regenerex® or Porous Plasma Spray Coating in Total knee Arthroplasty
Karen Dyreborg, Nikolaj Winther, Thomas Lind, Gunnar Flivik, Michael Mørk Petersen
Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Rigshospitalet; Department of Orthopaedic Surgery, Gentofte, Herlev Gentofte Hospital; Department of Orthopaedics, Skåne University Hospital, Lund; Department of Orthopaedic Surgery, Rigshospitalet


Background: Regenerex® is a porous titanium construct with a 3D interconnecting pore structure and biomechanical characteristics close to that of normal trabecular bone.
Purpose / Aim of Study: The aim of this study was to compare this structure to the Porous Plasma Sprayed (PPS) tibial implant, with non- interconnecting pore structure, after uncemented total knee arthroplasty (TKA).
Materials and Methods: 61 patients (mean age=63(49-71), F/M=35/26) planned for an uncemented Vanguard TKA (Biomet, Warsaw, Indiana, USA) at Hørsholm Hospital (n=41) or at Gentofte Hospital (n=20) were randomized to receive either a Regenerex® or a PPS tibial component (31/30). RadioSteriometric Analysis (RSA) using the tibial components, marker-based technique, was performed postoperatively, at 3 months, 6 months and at 1, 2 and 6 years with measurement of migration (segment motion and maximum total point motion (MTPM)). All patients had the clinical results monitored with the Knee Society knee and function scores. 55 patients attended the 6-year follow-up. Statistics: Mann-Whitney U test. Results are presented as mean (range).
Findings / Results: One patient had died and 4 was re- operated (infection=2, mechanical reasons=2) during the 6-year period. All reoperations were in the Regenerex®-group. The total 6-year MTPM was 1.40mm (0.51-3.71) for the PPS-group and 2.67mm (0.37-15.42) for the Regenerex®-group (p=0.43). The 2 to 6-year MTPM was 0.40mm (0.10-3.01) in the PPS-group and 0.56mm (0.11-4.48) in the Regenerex®-group (p=0.61).
Conclusions: We did not find any significant differences between the PPS- and Regenerex®-group with regards to total long-term migration or migration beyond 2 years. Since no patient was revised due to aseptic loosening both implants are considered to work well with regards to tibial component fixation and biocompatibility.

44. Mismatch Never Events in Hip and Knee Arthroplasty: A Cohort and Intervention Study
Anders Odgaard, Mogens Berg Laursen, Kirill Gromov, Anders Troelsen, Frank Madsen, Overgaard Overgaard
Dept. of Orthopaedics, Copenhagen University Hospital Herlev-Gentofte; Dept. of Orthopaedics, Aalborg University Hospital; Dept. of Orthopaedics, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedics, Copenhagen University Hospital Hvidovre; Dept. of Orthopaedics, Aarhus University Hospital; Dept. of Orthopaedics, Odense University Hospital


Background: Incompatible components in hip or knee arthroplasty may lead to a risk of malfunction and early failure. These mismatch never events are known to happen, but the frequency is largely unknown.
Purpose / Aim of Study: We aimed to 1) calculate frequencies of implant incompatibility in sequentially registered implants and 2) assess whether an online warning system can reduce the frequency of mismatch never events.
Materials and Methods: Barcode implant registration was introduced in 11 hospitals from 2013. We developed a compatibility database covering all implant families used, and from May 2017, compatibility checking became part of the registration process, immediately warning theatre staff, if incompatible implants were registered. Hospitals were contacted to verify every case of recorded mismatch, that had occurred both before and after the introduction of real-time checking. We defined four classes (A-I, A-II, B-I and B-II) of component mismatch depending on an assessment of patient risk (A/B) and on whether the mismatch was knowingly accepted (I/II).
Findings / Results: Implants from a total of 22,564 hip or knee arthroplasty procedures were analyzed. Implant information from 12,306 arthroplasty procedures was collected before the introduction of the compatibility checking, and from 5,691 hip and 6,615 knee arthroplasty procedures, we found a class A-I mismatch rate of 0.14% (95% CI: 0.06%-0.28%) and 0.17% (95% CI: 0.08%-0.30%), respectively. After the introduction of compatibility checking, implants from a total of 10,258 procedures were analyzed, and we identified no class A-I mismatches for hips (p=0.008) or knees (p=0.003).
Conclusions: Our data presents validated estimates of the frequency of mismatch never events for hip and knee arthroplasty procedures, and it demonstrates that a significant reduction in class A-I mismatches is possible.

45. Does preoperative Pain Catastrophizing predict physical function after Knee Arthroplasty?
Sara Birch, Maiken Stilling, Inger Mechlenburg, Torben Bæk Hansen
Department of Physiotherapy and Occupational therapy, Holstebro Regional Hospital; University Clinic for Hand, Hip and Knee surgery, Holstebro Regional Hospital; Department of Orthopaedic Surgery, Aarhus University Hospital; University Clinic for Hand, Hip and Knee surgery, Holstebro Regional Hospital


Background: Pain catastrophizing might contribute to acute and long-term pain after Knee Arthroplasty (KA), but the association between pain catastrophizing and physical function is not well studied.
Purpose / Aim of Study: 1) to examine the association between preoperative pain catastrophizing and physical function one year after surgery and 2) to investigate possible differences in pain, general health and physical function among two groups of patients with high and low preoperative pain catastrophizing score.
Materials and Methods: A total of 651 patients scheduled for KA were included in this study between marts 2011 and December 2013. The Pain Catastrophizing Scale (PCS) was completed prior to surgery and Oxford Knee Score (OKS), Short Form-36 (SF-36) and EuroQol- 5D (EQ-5D) were completed prior to surgery, and 4 and 12 months after the surgery.
Findings / Results: Of the 651 patients, 466 underwent Total Knee Arthroplasty and 185 received Unicompartmental Knee Arthroplasty. Mean age was 67.3 and 53.2% were females. Regression analysis showed no association between preoperative pain catastrophizing and change in OKS 12 months after surgery. Patients with preoperative PCS>21 had significantly lower OKS, SF-36 and EQ-5D and higher pain score than patients with PCS<11 both preoperative and 4 and 12 months postoperative.
Conclusions: The present findings did not support our hypothesis about an association between preoperative pain catastrophizing and change in OKS after the operation, but the findings suggest that patients with high levels of preoperative pain catastrophizing have lower physical function, poorer general health, and more pain both before and after KA, which indicate that interventions designed to reduce pain catastrophizing might have the potential to further improve outcome after KA.

46. Pain, sports participation, and physical function in 10-14 years olds with Patellofemoral Pain and Osgood Schlatter: A matched cross-sectional study of 252 adolescents
Rathleff Michael, Winiarski Lukasz, Krommes Kasper, Graven-Nielsen Thomas, Hölmich Per, Olesen Jens, Holden Sinead, Thorborg Kristian
SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University; Department of Physiotherapy and Occupational Therapy, Aalborg University Hospital; Sports Orthopedic Research Center-Copenhagen (SORC-C), Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre; Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Aalborg University; Sports Orthopedic Research Center-Copenhagen (SORC-C), Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre; Research Unit for General Practice in Aalborg, Department of Clinical Medicine, Aalborg University; SMI, Department of Health Science and Technology, Aalborg University; Sports Orthopedic Research Center-Copenhagen (SORC-C), Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre


Background: Patellofemoral pain (PFP) and Osgood Schlatter disease (OSD) are common knee complaints in adolescents, but knowledge on their relative impact is lacking.
Purpose / Aim of Study: To compare pain, physical activity and knee function between pain-free controls and adolescents diagnosed with PFP or OSD.
Materials and Methods: This age and sex matched cross- sectional study included 252 adolescents (aged 10-14 years): 151 with PFP, 51 with OSD, and 50 controls. Pain, physical activity, knee function, and quality of life were collected using self-reported questionnaires. Hip and knee strength were measured with handheld dynamometry. Objective measure of physical activity was collected using ActiGraphs.
Findings / Results: Over 98% of adolescents with PFP or OSD participated regularly in sports prior to their knee pain, and 50% had reduced sports participation due to knee pain. Adolescents with PFP or OSD scored 23-57 points lower (P<0.001) in the Knee injury and Osteoarthritis Outcome Score subscales compared with controls, with the lowest scores in the ‘sport & recreation’ and ‘quality of life’. Girls and boys with OSD had significantly lower isometric knee strength compared to controls (26-37%, P<0.001), whereas only girls with PFP displayed lower hip extension strength compared to controls (15%, P<0.05). Adolescents with PFP or OSD accumulated more than 2 hours of vigorous physical activity per day.
Conclusions: Adolescents with PFP or OSD are characterised by impaired sports participation and knee function, relative to pain-free controls, suggesting that future interventions for this group need to focus on restoring sports-related function and sports participation. As both boys and girls with OSD showed substantially decreased knee extension strength, interventions aimed at this deficit need to be considered in the future.

47. Pharmacokinetics of high-dose Ropivacaine for local infiltration anesthesia in unilateral and simultaneous bilateral total knee arthroplasty
Kirill Gromov, Stanislas Delyle, Nicolai Bang Foss, Lars Møller Pedersen, Christian Skovgaard Nielsen, Elodie Lamy, Anders Troelsen, Saik Urien, Henrik Husted
Department of Orthopaedic Surgery, Hvidovre Hospital; Plateforme de Spectrométrie, Université de Versailles Saint-Quentin-en-Yvelines; Department of Anaesthesiology , Hvidovre Hospital; Department of Anaesthesiology , Hvidovre Hospital; Department of Orthopaedic Surgery, Hvidovre Hospital; Plateforme de Spectrométrie, Université de Versailles Saint-Quentin-en-Yvelines; Department of Orthopaedic Surgery, Hvidovre Hospital; Plateforme de Spectrométrie, Université de Versailles Saint-Quentin-en-Yvelines; Department of Orthopaedic Surgery, Hvidovre Hospital


Background: Ropivacaine is commonly used in local infiltration anesthesia (LIA) as pain management following total knee arthroplasty (TKA). Systemic toxic thresholds of 4300 ng/mL and 560 ng/mL for total and free plasma Ropivacaine, respectively, have been suggested. Although considered safe, no studies evaluate pharmacokinetic properties and serum concentration of high dose Ropivacaine infiltration in unilateral TKA (uTKA) and bilateral simultaneous TKA (SBTKA).
Purpose / Aim of Study: The purpose of this study was to describe Ropivacaine concentrations in patients undergoing uTKA and SBTKA receiving LIA with high dose Ropivacain.
Materials and Methods: 16 unilateral and 15 SBTKA patients were included. All patients were operated in a fast-track setup without use of drains or tourniquet. Standard LIA technique was used with 200mL 0.2% Ropivacaine (400mg) injected periarticular in each knee. Free and bound serum concentrations of Ropivacaine was measured at 9 and 12 time points within 24 hours after first injection for uTKA and SBTKA, respectively, using liquid chronomatography mass spectrometry.
Findings / Results: Mean peak free Ropivacaine concentration was 30 ng/mL and 95ng /mL for uTKA and SBTKA, respectively. Mean peak bound Ropivacaine concentration was 756 ng/mL and 1695 ng/mL for uTKA and SBTKA, respectively. Peak concentration for both free and bound Ropivacaine was reached between 2 and 4 hours after first injection both for uTKA and SBTKA. There was no difference in the proportion of free Ropivacaine between unilateral TKA and BSTKA at any time points.
Conclusions: Peak free and peak bound Ropivacaine concentrations stayed way below previously proposed toxic thresholds in patients undergoing uTKA as well as SBTKA receiving LIA with high dose Ropivacaine

48. The survival of TKAs converted from medial UKA resembles the survival of revision TKAs and not primary TKAs – Results from the Danish Knee Arthroplasty Registry
Anders El-Galaly, Andreas Kappel, Poul Torben Nielsen, Steen Lund Jensen
Department of Orthopaedic Surgery, Aalborg University Hospital; Department of Orthopaedic Surgery, Aalborg University Hospital; Department of Orthopaedic Surgery, Aalborg University Hospital; Department of Orthopaedic Surgery, Aalborg University Hospital


Background: Medial UKA is increasingly popular but may subsequently be converted to a TKA. It is debated whether the survival of these conversion TKAs (uTKA) resembles the survival of primary TKAs (pTKA) or TKA to TKA revisions (rTKA).
Purpose / Aim of Study: To evaluate the survival of uTKA and compare it with pTKA and rTKA.
Materials and Methods: 1.005 uTKAs conducted between 1997 and 2017 were retrieved from the Danish Knee Arthroplasty Registry and compared to 88.713 pTKAs and 3.535 rTKAs. Patients and surgery details were analyzed. Implant survival was estimated by Kaplan Meier analysis and Cox Regression was used to estimate the association between survival and clinical features.
Findings / Results: Median time from UKA to TKA was 2.3 years and the most frequent indications for conversion were aseptic loosening (27%), pain (26%) and progressive osteoarthritis (14%). Mean age of uTKA was lower (66 years) than both rTKA (69 years) and pTKA (69 years) (p<0.001). 5- and 10-year implant survival were comparable between uTKA and rTKA (0.90 vs 0.91 and 0.86 vs 0.88, p=0.31) and both were lower than pTKA (0.97 and 0.96, p<0.001). Correspondingly, uTKA and rTKA had a similar adjusted hazard ratio (HR) for revision when compared to pTKA (2.82 vs 2.86, p<0.001). Early conversion of UKA (<2.3 years) was associated with an increased risk of revision (HR=1.72, p=0.02). Conversion due to aseptic loosening or pain did not influence the risk of revision, while conversion due to progressive osteoarthritis lowered the risk (HR=0.23, p<0.01).
Conclusions: Regarding survival, a TKA converted from a medial UKA behaves like a revision TKA but is inferior to a primary TKA. Early conversion increased the risk of revision whereas conversion due to progressive osteoarthritis lowered the risk.