Session 13: Knee
19. November
13:30 - 15:00
Lokale: 202-203
Chairmen: Martin Lindberg-Larsen & Søren Rytter
Rasmus Husted, Anders Troelsen, Henrik Husted, Birk Grønfeldt, Kristian Thorborg, Thomas Kallemose, Michael Rathleff, Thormas Bandholm
Clinical Research Centre, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Physical Medicine & Rehabilitation Research - Copenhagen (PMR-C); Department of Physical and Occupational Therapy; Clinical Research Centre; Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Clinical Orthopedic Research Hvidovre (CORH), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Sports Orthopaedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Center for General Practice at Aalborg University, Aalborg, Denmark; Department of Occupational Therapy and Physiotherapy, Aalborg University Hospital, Aalborg, Denmark; Department of Health Science and Technology, Aalborg University, Denmark.
Background: Guidelines recommend that exercise has been tried before surgery is considered in patients with severe knee osteoarthritis (OA). Low knee-extensor strength is associated with worse symptoms in patients with knee OA. Exercise may play a role improving knee-extensor strength and physical function before surgery, but the optimal dosage is unclear.
Aim: To compare the efficacy of three knee-extensor strength exercise dosages on knee-extensor strength and patient-reported outcomes before surgery in patients eligible for knee replacement.
Materials and Methods: One-hundred and forty patients eligible for knee replacement were randomized to 2, 4 or 6 home- based knee-extensor exercise-sessions per week for 12 weeks. Eligibility for surgery was assessed by an orthopedic surgeon. Exercise instruction was done by a physiotherapist. The primary outcome was change in knee-extensor strength after 12 weeks. Secondary outcomes were: “need for surgery?” – re-evaluation of treatment, change in Oxford Knee Score, Knee Osteoarthritis Outcome Score, average knee pain last week (0-10 numeric rating scale), 6- minute walk test and stair climbing test. Intention-to-treat, One-way ANOVA statistics were used to analyze between-group differences. ClinicalTrials.gov ID: NCT02931058.
Results: After 12 weeks of exercise, data were available for 117 patients (39/group). Primary outcome: no difference between the three groups on knee- extensor strength at 12 weeks. Secondary outcomes: “need for surgery?” (all groups): 38 (32.5%) patients wanted surgery, 79 (67.5%) postponed surgery, and there was significant difference between group “2 sessions/week” and “6 sessions/week” for Oxford Knee Score (4.2 [95% CI 0.6 to 7.8], P=0.02) and average knee pain last week (NRS 0-10) (-1.1 [95% -2.2 to -0.1], P=0.03) in favour of two sessions per week. No other differences were observed.
Interpretation / Conclusion: Prescribing knee-extensor exercise for 2, 4 or 6 times per week result in the same levels of knee- extensor strength after 12 weeks. However, two home-based exercise sessions a week seems superior in relation to patient-reported outcomes – and importantly – only one of three patients wanted surgery after home-based knee-extensor exercise.
Clinical Research Centre, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Physical Medicine & Rehabilitation Research - Copenhagen (PMR-C); Department of Physical and Occupational Therapy; Clinical Research Centre; Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Clinical Orthopedic Research Hvidovre (CORH), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Sports Orthopaedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; Center for General Practice at Aalborg University, Aalborg, Denmark; Department of Occupational Therapy and Physiotherapy, Aalborg University Hospital, Aalborg, Denmark; Department of Health Science and Technology, Aalborg University, Denmark.
Background: Guidelines recommend that exercise has been tried before surgery is considered in patients with severe knee osteoarthritis (OA). Low knee-extensor strength is associated with worse symptoms in patients with knee OA. Exercise may play a role improving knee-extensor strength and physical function before surgery, but the optimal dosage is unclear.
Aim: To compare the efficacy of three knee-extensor strength exercise dosages on knee-extensor strength and patient-reported outcomes before surgery in patients eligible for knee replacement.
Materials and Methods: One-hundred and forty patients eligible for knee replacement were randomized to 2, 4 or 6 home- based knee-extensor exercise-sessions per week for 12 weeks. Eligibility for surgery was assessed by an orthopedic surgeon. Exercise instruction was done by a physiotherapist. The primary outcome was change in knee-extensor strength after 12 weeks. Secondary outcomes were: “need for surgery?” – re-evaluation of treatment, change in Oxford Knee Score, Knee Osteoarthritis Outcome Score, average knee pain last week (0-10 numeric rating scale), 6- minute walk test and stair climbing test. Intention-to-treat, One-way ANOVA statistics were used to analyze between-group differences. ClinicalTrials.gov ID: NCT02931058.
Results: After 12 weeks of exercise, data were available for 117 patients (39/group). Primary outcome: no difference between the three groups on knee- extensor strength at 12 weeks. Secondary outcomes: “need for surgery?” (all groups): 38 (32.5%) patients wanted surgery, 79 (67.5%) postponed surgery, and there was significant difference between group “2 sessions/week” and “6 sessions/week” for Oxford Knee Score (4.2 [95% CI 0.6 to 7.8], P=0.02) and average knee pain last week (NRS 0-10) (-1.1 [95% -2.2 to -0.1], P=0.03) in favour of two sessions per week. No other differences were observed.
Interpretation / Conclusion: Prescribing knee-extensor exercise for 2, 4 or 6 times per week result in the same levels of knee- extensor strength after 12 weeks. However, two home-based exercise sessions a week seems superior in relation to patient-reported outcomes – and importantly – only one of three patients wanted surgery after home-based knee-extensor exercise.
Sebastian Breddam Mosegaard, Frank Madsen, Anders Odgaard, Per Wagner Kristensen, Kjeld Søballe, Maiken Stilling
Department of Orthopaedic Surgery, Aarhus University Hospital, 8200 Aarhus N, Denmark; Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark; Department of Orthopaedic Surgery, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark; Department of Orthopaedic Surgery, Vejle Hospital, 7100 Vejle, Denmark
Background: Many studies have investigated the tibial component migration but the knowledge on femoral component migration is limited.
Aim: This study aimed to examine the potential fixation difference between cemented single-peg (CS), cemented double-peg (CD) and cementless double-peg (CLD) femoral components of medial unicompartmental knee arthroplasty (UKA).
Materials and Methods: 80 patients (mean age = 63 years, 48 males) with medial knee osteoarthritis were randomized 3-ways to cemented single-peg UKR (n=29), cemented double-peg UKR (n=26) or cementless double-peg femoral UKR components (n=25). Patients were followed 5 years postoperatively with RSA and bone mineral density (BMD).
Results: At 5-years follow-up, femoral component total translation was comparable between the CS, CD and CLD group (p=0.60). The femoral internal/external rotation was 0.17 degrees (95% CI: -0.04 – 0.37) for the CS group, 0.62 degrees (95% CI: 0.40 – 0.84) for the CD group, and 0.50 degrees (95% CI: 0.28 – 0.71) for the CLD group, with higher rotation in the CD group than the CS group (p=0.01). There was no correlation between periprosthetic BMD and component migration.
Interpretation / Conclusion: Considering cemented single-peg femoral components as reference, cemented double-peg components showed slightly higher internal/external rotation at 5-years follow-up, which although statistically significant might not be clinically relevant. There was no dependency on periprosthetic bone mineral density.
Department of Orthopaedic Surgery, Aarhus University Hospital, 8200 Aarhus N, Denmark; Department of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark; Department of Orthopaedic Surgery, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark; Department of Orthopaedic Surgery, Vejle Hospital, 7100 Vejle, Denmark
Background: Many studies have investigated the tibial component migration but the knowledge on femoral component migration is limited.
Aim: This study aimed to examine the potential fixation difference between cemented single-peg (CS), cemented double-peg (CD) and cementless double-peg (CLD) femoral components of medial unicompartmental knee arthroplasty (UKA).
Materials and Methods: 80 patients (mean age = 63 years, 48 males) with medial knee osteoarthritis were randomized 3-ways to cemented single-peg UKR (n=29), cemented double-peg UKR (n=26) or cementless double-peg femoral UKR components (n=25). Patients were followed 5 years postoperatively with RSA and bone mineral density (BMD).
Results: At 5-years follow-up, femoral component total translation was comparable between the CS, CD and CLD group (p=0.60). The femoral internal/external rotation was 0.17 degrees (95% CI: -0.04 – 0.37) for the CS group, 0.62 degrees (95% CI: 0.40 – 0.84) for the CD group, and 0.50 degrees (95% CI: 0.28 – 0.71) for the CLD group, with higher rotation in the CD group than the CS group (p=0.01). There was no correlation between periprosthetic BMD and component migration.
Interpretation / Conclusion: Considering cemented single-peg femoral components as reference, cemented double-peg components showed slightly higher internal/external rotation at 5-years follow-up, which although statistically significant might not be clinically relevant. There was no dependency on periprosthetic bone mineral density.
Mette Mikkelsen, Andrew Price, Alma Pedersen, Kirill Gromov, Anders Troelsen
Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Nuffield Dept. of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, England; Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark
Background: Medial Unicompartmental knee arthroplasties (UKA) have historically produced revision rates up to six times higher than those of total knee arthroplasty (TKA). However, resent changes to practice have been linked to improved implant survival for UKA, leading to the hypothesis that the risk of revision for UKA has decreased over the last 20 years.
Aim: Therefore, the aims were to 1) investigate changes to revision risk for UKA over the last 20 years compared to TKA, 2) identify implant, surgery or patient factors that correlate to UKA revision risk and 3) describe the survival probability for the current UKA and TKA practice.
Materials and Methods: All knee replacements reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were linked to the National Patient Register and the Civil Registration System for information on comorbidities, emigration and mortality. We included all primary UKA and TKA performed due to primary osteoarthritis and propensity score matched TKA procedures to UKA procedures in a 4:1 ratio. Revision and mortality were analyzed using competing risk cox regression with a shared gamma frailty component.
Results: The matched cohort included 48,195 primary knee arthroplasties (9639 UKA). Difference in revision rates between UKA and TKA have significantly decreased over the last 20 years from 3-year hazard ratio 5.52 (CI 95 % 2.73-11.2) to 1.45 (CI 95 % 1.16- 1.81) due to increased UKA survival. Fixation mode, UKA usage rates and surgical volume all significantly modified the revision risk for UKA, and changed parallel to the decreasing revision risks. Thus the current typical UKA practice using cementless fixation at high usage unit has increased the 3-year implant survival to 96.4 % (CI 95 % 97.4- 95.4) which is 1.1 % lower than that of current TKA practice.
Interpretation / Conclusion: There has been a decrease in UKA revision risk over the last 20 years, reducing the difference in revision risk between UKA and TKA. High usage rates, surgical volume and the use of cementless fixation have increased during the study period and were all associated with lower UKA revision risks.
Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Nuffield Dept. of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, England; Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark
Background: Medial Unicompartmental knee arthroplasties (UKA) have historically produced revision rates up to six times higher than those of total knee arthroplasty (TKA). However, resent changes to practice have been linked to improved implant survival for UKA, leading to the hypothesis that the risk of revision for UKA has decreased over the last 20 years.
Aim: Therefore, the aims were to 1) investigate changes to revision risk for UKA over the last 20 years compared to TKA, 2) identify implant, surgery or patient factors that correlate to UKA revision risk and 3) describe the survival probability for the current UKA and TKA practice.
Materials and Methods: All knee replacements reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were linked to the National Patient Register and the Civil Registration System for information on comorbidities, emigration and mortality. We included all primary UKA and TKA performed due to primary osteoarthritis and propensity score matched TKA procedures to UKA procedures in a 4:1 ratio. Revision and mortality were analyzed using competing risk cox regression with a shared gamma frailty component.
Results: The matched cohort included 48,195 primary knee arthroplasties (9639 UKA). Difference in revision rates between UKA and TKA have significantly decreased over the last 20 years from 3-year hazard ratio 5.52 (CI 95 % 2.73-11.2) to 1.45 (CI 95 % 1.16- 1.81) due to increased UKA survival. Fixation mode, UKA usage rates and surgical volume all significantly modified the revision risk for UKA, and changed parallel to the decreasing revision risks. Thus the current typical UKA practice using cementless fixation at high usage unit has increased the 3-year implant survival to 96.4 % (CI 95 % 97.4- 95.4) which is 1.1 % lower than that of current TKA practice.
Interpretation / Conclusion: There has been a decrease in UKA revision risk over the last 20 years, reducing the difference in revision risk between UKA and TKA. High usage rates, surgical volume and the use of cementless fixation have increased during the study period and were all associated with lower UKA revision risks.
Christian Bredgaard Jensen, Pelle Baggesgaard Petersen, Christoffer Calov Jørgensen, Henrik Kehlet, Anders Troelsen, Kirill Gromov
Clinical Orthopaedic Research Hvidovre, Department of Orthopaedic Surgery, Hvidovre Hospital; Section for Surgical Pathophysiology, Rigshospitalet; Lundbeck Foundation Centre for Fast-track Hip and Knee Arthroplasty.
Background: It is still debated whether to use unicompartmental (UKA) or total knee arthroplasty (TKA) in appropriate osteoarthritis cases. UKA potentially offers faster recovery and fewer short-term complications. However, studies are reporting differences in preoperative comorbidity between TKA and UKA patients that could be affecting outcomes.
Aim: The aim of this study was to investigate differences in length of postoperative stay (LOS), readmissions and complications within 90 days of surgery between propensity score matched UKA and TKA patients.
Materials and Methods: UKA and TKA patients, operated in well-defined fast-track setup, from nine orthopaedic centers were included in this study. Propensity score matching (intended ratio = 1:3 [UKA:TKA]) was used to address differences in preoperative comorbidity between UKA and TKA patients resulting in a matched cohort of 2786 UKA patients and 7708 TKA patients. Univariable regression models, multivariable mixed effects models with surgical center as a random effect, and Chi-Squared test were used to investigate differences in LOS, readmission and complication rates between UKA and TKA patients.
Results: No indications of imbalance within demography and preoperative comorbidity were present between groups after matching. The UKA-group had a lower LOS compared to the TKA-group (median LOS 1 vs 2 days, p<0.001). UKA patients were more likely to be discharged on the day of surgery (OR = 38.5 [95% CI 27.0-52.6]) and less likely to have a LOS > 2 days (OR = 0.20 [95% CI 0.17-0.24]) compared to TKA patients. There was no difference in 90-day readmission rate. UKA patients had fewer prosthetic joint infections (OR = 0.50 [95% CI 0.26-0.99]) and reoperations (OR = 0.40 [0.20-0.81]) compared to TKA patients. However, aseptic revisions were more frequent in UKA patients compared to TKA patients (OR = 2.5 [95% CI 1.1-6.0]).
Interpretation / Conclusion: UKA patients had shorter hospital stays, a higher rate of discharge on the day of surgery, fewer prosthetic joint infections and reoperations compared to TKA patients. However, TKA patients had fewer aseptic revisions. Our findings support the use of UKA in a fast-track setup whenever indicated.
Clinical Orthopaedic Research Hvidovre, Department of Orthopaedic Surgery, Hvidovre Hospital; Section for Surgical Pathophysiology, Rigshospitalet; Lundbeck Foundation Centre for Fast-track Hip and Knee Arthroplasty.
Background: It is still debated whether to use unicompartmental (UKA) or total knee arthroplasty (TKA) in appropriate osteoarthritis cases. UKA potentially offers faster recovery and fewer short-term complications. However, studies are reporting differences in preoperative comorbidity between TKA and UKA patients that could be affecting outcomes.
Aim: The aim of this study was to investigate differences in length of postoperative stay (LOS), readmissions and complications within 90 days of surgery between propensity score matched UKA and TKA patients.
Materials and Methods: UKA and TKA patients, operated in well-defined fast-track setup, from nine orthopaedic centers were included in this study. Propensity score matching (intended ratio = 1:3 [UKA:TKA]) was used to address differences in preoperative comorbidity between UKA and TKA patients resulting in a matched cohort of 2786 UKA patients and 7708 TKA patients. Univariable regression models, multivariable mixed effects models with surgical center as a random effect, and Chi-Squared test were used to investigate differences in LOS, readmission and complication rates between UKA and TKA patients.
Results: No indications of imbalance within demography and preoperative comorbidity were present between groups after matching. The UKA-group had a lower LOS compared to the TKA-group (median LOS 1 vs 2 days, p<0.001). UKA patients were more likely to be discharged on the day of surgery (OR = 38.5 [95% CI 27.0-52.6]) and less likely to have a LOS > 2 days (OR = 0.20 [95% CI 0.17-0.24]) compared to TKA patients. There was no difference in 90-day readmission rate. UKA patients had fewer prosthetic joint infections (OR = 0.50 [95% CI 0.26-0.99]) and reoperations (OR = 0.40 [0.20-0.81]) compared to TKA patients. However, aseptic revisions were more frequent in UKA patients compared to TKA patients (OR = 2.5 [95% CI 1.1-6.0]).
Interpretation / Conclusion: UKA patients had shorter hospital stays, a higher rate of discharge on the day of surgery, fewer prosthetic joint infections and reoperations compared to TKA patients. However, TKA patients had fewer aseptic revisions. Our findings support the use of UKA in a fast-track setup whenever indicated.
Kristine B. Arndt, Henrik M. Schrøder, Anders Troelsen, Martin Lindberg-Larsen
Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthorpaedic Surgery, Naestved Hospital; Department of Orthopaedic Surgery, Copenhagen University Hospital, Hvidovre; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: Patients having a knee arthroplasty revised on the indication “pain without loosening” are thought to experience a worse outcome than patients revised on other indications.
Aim: The purpose of this study is to investigate the survival of knee arthroplasties revised on the indication “pain without loosening” compared to “aseptic loosening” and to compare survival rates over two time-periods, 1997-2009 and 2010-2018.
Materials and Methods: This is a retrospective cohort study on data from the Danish Knee Arthroplasty Register (DKR) and the Danish National Patient Register (DNPR). The main outcomes are incidence rates of re-revisions reported as proportions. Competing risks regression adjusted for other variables.
Results: 3753 knee revision arthroplasties were performed in the period 1997-2018. 1111 (29.6%) on the indication “pain without loosening” and 2642 (70.4%) on the indication “aseptic loosening”. The cumulated incidences of re- revision in the “pain without loosening”-cohort after 2, 5 and 20 years were 11.6% [9.9;13.6], 17.7% [15.6;20.1] and 22.6% [20.2;25.1] and in the “aseptic loosening”-cohort 10.5% [9.4;11.8], 15.6% [14.3;17.1] and 19.0% [17.5;20.5]. Subhazard ratio for re-revision comparing “pain without loosening” to “aseptic loosening” was 1.08 [0.89;1.31], p=0.414. The risk of re-revision in the “pain without loosening”-cohort in the first period at 2, 5 and 8 years was 11.1% [8.7;14.0], 18.0% [15.0;21.5] and 22.0% [18.6;25.7]. The risk of re-revision in the second time-period at 2, 5 and 8 years was 12.2% [9.7;15.0], 17.5% [14.6;20.8] and 18.2% [15.2;21.5]. The risk of re- revision in the “aseptic loosening”-cohort in the first time-period was 11.4% [9.6;13.4], 18.5% [16.3;20.9] and 21.7% [19.3;24.3]. In the second time-period the risk was 9.9% [8.6;11.5], 13.7% [12.1;15.5] and 14.6% [12.9;16.4].
Interpretation / Conclusion: We did not find an increased risk of re-revision for patients having a knee arthroplasty revised on the indication “pain without loosening” compared to “aseptic loosening”. The survival rates improved from 2010-2018 compared to 1997-2009 on both indications.
Department of Orthopaedic Surgery and Traumatology, Odense University Hospital; Department of Orthorpaedic Surgery, Naestved Hospital; Department of Orthopaedic Surgery, Copenhagen University Hospital, Hvidovre; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital
Background: Patients having a knee arthroplasty revised on the indication “pain without loosening” are thought to experience a worse outcome than patients revised on other indications.
Aim: The purpose of this study is to investigate the survival of knee arthroplasties revised on the indication “pain without loosening” compared to “aseptic loosening” and to compare survival rates over two time-periods, 1997-2009 and 2010-2018.
Materials and Methods: This is a retrospective cohort study on data from the Danish Knee Arthroplasty Register (DKR) and the Danish National Patient Register (DNPR). The main outcomes are incidence rates of re-revisions reported as proportions. Competing risks regression adjusted for other variables.
Results: 3753 knee revision arthroplasties were performed in the period 1997-2018. 1111 (29.6%) on the indication “pain without loosening” and 2642 (70.4%) on the indication “aseptic loosening”. The cumulated incidences of re- revision in the “pain without loosening”-cohort after 2, 5 and 20 years were 11.6% [9.9;13.6], 17.7% [15.6;20.1] and 22.6% [20.2;25.1] and in the “aseptic loosening”-cohort 10.5% [9.4;11.8], 15.6% [14.3;17.1] and 19.0% [17.5;20.5]. Subhazard ratio for re-revision comparing “pain without loosening” to “aseptic loosening” was 1.08 [0.89;1.31], p=0.414. The risk of re-revision in the “pain without loosening”-cohort in the first period at 2, 5 and 8 years was 11.1% [8.7;14.0], 18.0% [15.0;21.5] and 22.0% [18.6;25.7]. The risk of re-revision in the second time-period at 2, 5 and 8 years was 12.2% [9.7;15.0], 17.5% [14.6;20.8] and 18.2% [15.2;21.5]. The risk of re- revision in the “aseptic loosening”-cohort in the first time-period was 11.4% [9.6;13.4], 18.5% [16.3;20.9] and 21.7% [19.3;24.3]. In the second time-period the risk was 9.9% [8.6;11.5], 13.7% [12.1;15.5] and 14.6% [12.9;16.4].
Interpretation / Conclusion: We did not find an increased risk of re-revision for patients having a knee arthroplasty revised on the indication “pain without loosening” compared to “aseptic loosening”. The survival rates improved from 2010-2018 compared to 1997-2009 on both indications.
Mikkel Rathsach Andersen, Winther Nikolaj, Lind Thomas, Henrik Morville Schrøder, Gunnar Flivik, Michael Mørk Petersen
Background: Radiostereometric analysis (RSA) studies have shown that continuous migration of tibia components can predict aseptic loosening after total knee replacement (TKA). In this study we investigated if accurate size and placement of the tibia components, could be related to the degree of migration using RSA measurements.
Aim: To investigate if undersizing/oversizing, malalignment of the tibia component is related to higher degrees of component migration.
Materials and Methods: We performed 2 year follow up of 111 patients who underwent TKA surgery with cementless tibia components. Radiostereometric analysis was performed postoperatively and after 3, 6, 12 and 24 months. Postoperative X-rays were evaluated with respect to component size and placement in the tibia, by experienced knee surgeons blinded to migration data, and clinical outcome. Statistics: Multivariate linear regression analysis
Results: Continuous migration (12-24 months) was negatively related to tibia component under-sizing -0.2 (CI -.33 – -.08). Subsidence was related to absence of posterior cortical support -0.7 (CI -1.09 – -.28), absence of lateral cortical support 0.8 (CI .29 – 1.37) and frontal plane varus malalignment 0.6 (CI .12 – 1.16) and component under-sizing -0.4 (CI -.06 – -.68). Posterior tilt was related only under-sizing 0.6 (CI .27 – 1.11).
Interpretation / Conclusion: Undersized cementless tibia components are at risk of poor fixation with continuous migration, and therefore higher risk of aseptic loosening should be expected.
Background: Radiostereometric analysis (RSA) studies have shown that continuous migration of tibia components can predict aseptic loosening after total knee replacement (TKA). In this study we investigated if accurate size and placement of the tibia components, could be related to the degree of migration using RSA measurements.
Aim: To investigate if undersizing/oversizing, malalignment of the tibia component is related to higher degrees of component migration.
Materials and Methods: We performed 2 year follow up of 111 patients who underwent TKA surgery with cementless tibia components. Radiostereometric analysis was performed postoperatively and after 3, 6, 12 and 24 months. Postoperative X-rays were evaluated with respect to component size and placement in the tibia, by experienced knee surgeons blinded to migration data, and clinical outcome. Statistics: Multivariate linear regression analysis
Results: Continuous migration (12-24 months) was negatively related to tibia component under-sizing -0.2 (CI -.33 – -.08). Subsidence was related to absence of posterior cortical support -0.7 (CI -1.09 – -.28), absence of lateral cortical support 0.8 (CI .29 – 1.37) and frontal plane varus malalignment 0.6 (CI .12 – 1.16) and component under-sizing -0.4 (CI -.06 – -.68). Posterior tilt was related only under-sizing 0.6 (CI .27 – 1.11).
Interpretation / Conclusion: Undersized cementless tibia components are at risk of poor fixation with continuous migration, and therefore higher risk of aseptic loosening should be expected.
Mette Mikkelsen, Lasse Enkebølle Rasmussen, Andrew Price, Alma Pedersen, Kirill Gromov, Anders Troelsen
Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopedic Surgery, Vejle Hospital, Beriderbakken 4, 7100 Vejle, Denmark; Nuffield Dept. of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, England; Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark.
Background: The changes to practice for medial unicompartmental knee arthroplasty (UKA) seen in recent years, have been linked to decreased UKA revision risk. Is the decreased risk due to a decreased risk for all revision indications, or is it linked to a few select indications?
Aim: We aimed to determine the national revision indication pattern and the timing for revision by indication for UKA and Total Knee Arthroplasty (TKA). Secondly, to investigate any changes to UKA revision indication patterns over time and any correlation to recent changes in UKA practice.
Materials and Methods: All primary knee replacements performed due to primary osteoarthritis and their revisions reported to the Danish Knee Arthroplasty Register in 1997-2017 were included. Complex surgeries were excluded. Comorbidity, mortality and emigration status was obtained from the National Patient Register and Civil Registration System. TKA procedures were propensity score matched 4:1 to UKA procedures. Revision risks were compared using competing risk cox proportional hazard regression with a shared gamma frailty component to account for bilateral cases.
Results: Loosening was the most common revision indication for both UKA (26.7 %) and TKA (29.5 %). Pain and disease progression accounted for 54.6 % of the remaining UKA revisions. Infections and instability accounted for 56.1 % of the remaining TKA revisions. TKA revisions were on average performed 6 months earlier than UKA revisions, due to differences in revision indication patterns. The prevalence of UKA revisions from loosening or pain have decreased over the last decade, and were in 2017 among the three least common indications. Cementless UKAs were less likely to get revised from pain (HR 0.40, CI 95 % 0.17-0.94) or loosening (HR 0.29, CI 95 % 0.10-0.81) than cemented UKAs. UKA revisions from pain (HR 0.67, CI 95% 0.50-0.91) or loosening (HR 0.51, CI 95 % 0.37-0.70) were less likely at high UKA usage units.
Interpretation / Conclusion: The overall 20 year revision patterns for UKA and TKA are comparable to previous published patterns. There has been a large change in revision pattern for UKA in the last decade, and with the current surgical practice, revision due to pain or loosening are significantly less likely.
Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopedic Surgery, Vejle Hospital, Beriderbakken 4, 7100 Vejle, Denmark; Nuffield Dept. of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, England; Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark; Dept. of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Copenhagen, Denmark.
Background: The changes to practice for medial unicompartmental knee arthroplasty (UKA) seen in recent years, have been linked to decreased UKA revision risk. Is the decreased risk due to a decreased risk for all revision indications, or is it linked to a few select indications?
Aim: We aimed to determine the national revision indication pattern and the timing for revision by indication for UKA and Total Knee Arthroplasty (TKA). Secondly, to investigate any changes to UKA revision indication patterns over time and any correlation to recent changes in UKA practice.
Materials and Methods: All primary knee replacements performed due to primary osteoarthritis and their revisions reported to the Danish Knee Arthroplasty Register in 1997-2017 were included. Complex surgeries were excluded. Comorbidity, mortality and emigration status was obtained from the National Patient Register and Civil Registration System. TKA procedures were propensity score matched 4:1 to UKA procedures. Revision risks were compared using competing risk cox proportional hazard regression with a shared gamma frailty component to account for bilateral cases.
Results: Loosening was the most common revision indication for both UKA (26.7 %) and TKA (29.5 %). Pain and disease progression accounted for 54.6 % of the remaining UKA revisions. Infections and instability accounted for 56.1 % of the remaining TKA revisions. TKA revisions were on average performed 6 months earlier than UKA revisions, due to differences in revision indication patterns. The prevalence of UKA revisions from loosening or pain have decreased over the last decade, and were in 2017 among the three least common indications. Cementless UKAs were less likely to get revised from pain (HR 0.40, CI 95 % 0.17-0.94) or loosening (HR 0.29, CI 95 % 0.10-0.81) than cemented UKAs. UKA revisions from pain (HR 0.67, CI 95% 0.50-0.91) or loosening (HR 0.51, CI 95 % 0.37-0.70) were less likely at high UKA usage units.
Interpretation / Conclusion: The overall 20 year revision patterns for UKA and TKA are comparable to previous published patterns. There has been a large change in revision pattern for UKA in the last decade, and with the current surgical practice, revision due to pain or loosening are significantly less likely.
Adam Omari, Lina Holm Ingelsrud, Thomas Quaade Bandholm, Susanne Irene Lentz, Anders Troelsen, Kirill Gromov
University of Copenhagen, Faculty of Health and Medical Sciences; Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre; Department of Clinical Research, Copenhagen University Hospital Hvidovre; Department of Physical – and Occupational Therapy, Copenhagen University Hospital Hvidovre
Background: The optimal rehabilitation strategy after a unicompartmental knee arthroplasty (UKA) is unclear.
Aim: We aimed to pilot study the effect of transitioning from a supervised to a self management rehabilitation regime by study of patient outcomes subsequent to UKA surgery.
Materials and Methods: Fifty consecutive patients scheduled to undergo unilateral UKA surgery at our institution between 22nd February 2016 and 18th of January 2017 were prospectively identified. Performed UKAs were grouped into two cohorts, Supervised Cohort and Self-management Cohort, temporally separated by new rehabilitation regime introduction. Self-management Cohort(n=25) received an extensive inpatient rehabilitation regime along with outpatient referral to rehabilitation center. The Self-management Cohort(n=25) were only instructed in use of crutches and free ambulation at own accord. Follow-up (F/U) was 1 year from receiving UKA. A range of outcomes were recorded, and between-cohort differences compared: knee joint range of motion, pain and functional limitations, length-of-stay, readmission rate, pain during activity and rest, and knee circumference.
Results: Complete data was obtained for n=45 patients. The mean between-cohort difference in ROM from preoperatively to discharge was 15.4 degrees (CI:5.2,25.8, p=0.004), favoring the supervised regime, with no difference at 3- or 12 months F/U. No significant difference was detected in other outcomes.
Interpretation / Conclusion: Transition to a simple rehabilitation regime following UKA surgery was associated with decreased ROM at discharge, which was not present at 3-and 12 months F/U. We found no other between-cohort differences for any other outcomes, although the study was likely underpowered for these outcomes. We encourage large-scale replication of these findings using randomized designs.
University of Copenhagen, Faculty of Health and Medical Sciences; Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre; Department of Clinical Research, Copenhagen University Hospital Hvidovre; Department of Physical – and Occupational Therapy, Copenhagen University Hospital Hvidovre
Background: The optimal rehabilitation strategy after a unicompartmental knee arthroplasty (UKA) is unclear.
Aim: We aimed to pilot study the effect of transitioning from a supervised to a self management rehabilitation regime by study of patient outcomes subsequent to UKA surgery.
Materials and Methods: Fifty consecutive patients scheduled to undergo unilateral UKA surgery at our institution between 22nd February 2016 and 18th of January 2017 were prospectively identified. Performed UKAs were grouped into two cohorts, Supervised Cohort and Self-management Cohort, temporally separated by new rehabilitation regime introduction. Self-management Cohort(n=25) received an extensive inpatient rehabilitation regime along with outpatient referral to rehabilitation center. The Self-management Cohort(n=25) were only instructed in use of crutches and free ambulation at own accord. Follow-up (F/U) was 1 year from receiving UKA. A range of outcomes were recorded, and between-cohort differences compared: knee joint range of motion, pain and functional limitations, length-of-stay, readmission rate, pain during activity and rest, and knee circumference.
Results: Complete data was obtained for n=45 patients. The mean between-cohort difference in ROM from preoperatively to discharge was 15.4 degrees (CI:5.2,25.8, p=0.004), favoring the supervised regime, with no difference at 3- or 12 months F/U. No significant difference was detected in other outcomes.
Interpretation / Conclusion: Transition to a simple rehabilitation regime following UKA surgery was associated with decreased ROM at discharge, which was not present at 3-and 12 months F/U. We found no other between-cohort differences for any other outcomes, although the study was likely underpowered for these outcomes. We encourage large-scale replication of these findings using randomized designs.
Emil Toft Petersen, Søren Rytter, Daan Koppens, Jesper Dalsgaard, Torben Bæk Hansen, Nis Elbrønd Larsen, Michael Skipper Andersen, Maiken Stilling
University Clinic for Hand, Hip and Knee Surgery Holstebro Central Hospital; Department of Clinical Medicine, Aarhus University; AutoRSA Research Group, Orthopeadic Research Unit, Aarhus University Hospital; Department of Orthopaedic Surgery, Aarhus University Hospital; Department of Radiology, Holstebro Central Hospital; Department of Radiology, Aarhus University; Department of Materials and Production, Aalborg University
Background: In an attempt to alleviate symptoms of the disease, patients with knee osteoarthrosis (KOA) frequently alter their gait patterns. Understanding the underlying pathomechanics and identifying KOA phenotypes is essential for improving treatments.
Aim: We aimed to investigate altered kinematics in patients with KOA to identify subgroups.
Materials and Methods: Sixty-six patients with symptomatic KOA scheduled for total knee arthroplasty and 12 age-matched healthy volunteers with asymptomatic knees were included. We used k-means to separate the patients based on dynamic radiostereometric assessed knee kinematics. Ligament lesions, KOA score, and clinical outcome were assessed by magnetic resonance imaging, radiographs, and patient reported outcome measures, respectively.
Results: We identified four clusters that were supported by clinical characteristics. Compared with the healthy group; The flexion group (n=20): revealed increased flexion, greater adduction, and joint narrowing and consisted primarily of patients with medial KOA. The abduction group (n=17): revealed greater abduction, joint narrowing and included primarily patients with lateral KOA. The anterior draw group (n=10): revealed greater anterior draw, external tibial rotation, lateral tibial shift, adduction, and joint narrowing. This group was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the greatest KOA score. The external rotation group (n=19): revealed greater external tibial rotation, lateral tibial shift, adduction, and joint narrowing while no anterior draw was observed. This group included primarily patients with medial collateral and posterior cruciate ligament lesions.
Interpretation / Conclusion: Patients with KOA can, based on their gait patterns, be classified into four subgroups, which relate to their clinical characteristics. The findings add to our understanding of associations between disease pathology characteristics in the knee and the pathomechanics in patients with KOA. A next step is to investigate if patients in the pathomechanic clusters have different outcomes following total knee arthroplasty.
University Clinic for Hand, Hip and Knee Surgery Holstebro Central Hospital; Department of Clinical Medicine, Aarhus University; AutoRSA Research Group, Orthopeadic Research Unit, Aarhus University Hospital; Department of Orthopaedic Surgery, Aarhus University Hospital; Department of Radiology, Holstebro Central Hospital; Department of Radiology, Aarhus University; Department of Materials and Production, Aalborg University
Background: In an attempt to alleviate symptoms of the disease, patients with knee osteoarthrosis (KOA) frequently alter their gait patterns. Understanding the underlying pathomechanics and identifying KOA phenotypes is essential for improving treatments.
Aim: We aimed to investigate altered kinematics in patients with KOA to identify subgroups.
Materials and Methods: Sixty-six patients with symptomatic KOA scheduled for total knee arthroplasty and 12 age-matched healthy volunteers with asymptomatic knees were included. We used k-means to separate the patients based on dynamic radiostereometric assessed knee kinematics. Ligament lesions, KOA score, and clinical outcome were assessed by magnetic resonance imaging, radiographs, and patient reported outcome measures, respectively.
Results: We identified four clusters that were supported by clinical characteristics. Compared with the healthy group; The flexion group (n=20): revealed increased flexion, greater adduction, and joint narrowing and consisted primarily of patients with medial KOA. The abduction group (n=17): revealed greater abduction, joint narrowing and included primarily patients with lateral KOA. The anterior draw group (n=10): revealed greater anterior draw, external tibial rotation, lateral tibial shift, adduction, and joint narrowing. This group was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the greatest KOA score. The external rotation group (n=19): revealed greater external tibial rotation, lateral tibial shift, adduction, and joint narrowing while no anterior draw was observed. This group included primarily patients with medial collateral and posterior cruciate ligament lesions.
Interpretation / Conclusion: Patients with KOA can, based on their gait patterns, be classified into four subgroups, which relate to their clinical characteristics. The findings add to our understanding of associations between disease pathology characteristics in the knee and the pathomechanics in patients with KOA. A next step is to investigate if patients in the pathomechanic clusters have different outcomes following total knee arthroplasty.
Pelle Baggesgaard Petersen, Mette Mikkelsen, Christoffer Calov Jørgensen, Anders Troelsen, Andreas Kappel, Henrik Kehlet, Kirill Gromov
Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Denmark; Department of Orthopaedics Aalborg University Hospital, Aalborg, Denmark.
Background: Venous thromboembolism (VTE) is an important postoperative complication to total knee arthroplasty (TKA). The introduction of fast-track has shown favorable outcomes with regards to risk of VTE. However, use of tourniquet has shown conflicting results for risk of VTE after TKA. To date no data exist on the associated risk for VTE after TKA using tourniquet in a fast-track set-up.
Aim: Consequently, we hypothesized that use of tourniquet in an unselected prospective multicenter fast-track TKA setting with in-hospital only thromboprophylaxis if length of stay (LOS) = 5 days were associated to increased risk of 90-day VTE.
Materials and Methods: We used an observational cohort study design from 9 dedicated fast-track centres including unselected unilateral primary TKA from 2010¬— 2017. Prospective collection of preoperative risk- factors, complete follow-up on LOS, 90-day readmissions and mortality from the Danish National Patient Registry; use of tourniquet from the Danish knee arthroplasty register; and identification of postoperative VTE from health records if LOS > 4 days or 90-day readmission. Risk analysis were performed using a mixed effects logistic regression model adjusting for previously identified risk-factors for 90-day VTE after fast-track THA and TKA (BMI, age, and history of VTE) as fixed effects and department as a random effect.
Results: Of the 16,267 procedures (39.1% males, mean age 67.9 (SD 10.0) years, median LOS 2 [IQR 2-3]) 12.518 (77.0%) were performed using a tourniquet (median duration 60 [51-70] min). The annual tourniquet usage varied greatly between departments from 0 % to 100%, but also within departments from 99% to 0%. The 90-day incidence of VTE was 77 (0.47%) without significant difference with or without tourniquet 52 (0.42%) vs 25 (0.67%) (p=0.056), respectively. This association remained insignificant with OR 0.62 (95% CI: 0.38-1.01, p=0.054) after adjustment for previously identified risk-factors.
Interpretation / Conclusion: The use of tourniquet was not associated to increased 90-day VTE risk after fast-track TKA. However, further investigations on the unexpected insignificant tendency of a protective effect of tourniquet is warranted.
Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre (CORH), Copenhagen University Hospital Hvidovre, Denmark; Department of Orthopaedics Aalborg University Hospital, Aalborg, Denmark.
Background: Venous thromboembolism (VTE) is an important postoperative complication to total knee arthroplasty (TKA). The introduction of fast-track has shown favorable outcomes with regards to risk of VTE. However, use of tourniquet has shown conflicting results for risk of VTE after TKA. To date no data exist on the associated risk for VTE after TKA using tourniquet in a fast-track set-up.
Aim: Consequently, we hypothesized that use of tourniquet in an unselected prospective multicenter fast-track TKA setting with in-hospital only thromboprophylaxis if length of stay (LOS) = 5 days were associated to increased risk of 90-day VTE.
Materials and Methods: We used an observational cohort study design from 9 dedicated fast-track centres including unselected unilateral primary TKA from 2010¬— 2017. Prospective collection of preoperative risk- factors, complete follow-up on LOS, 90-day readmissions and mortality from the Danish National Patient Registry; use of tourniquet from the Danish knee arthroplasty register; and identification of postoperative VTE from health records if LOS > 4 days or 90-day readmission. Risk analysis were performed using a mixed effects logistic regression model adjusting for previously identified risk-factors for 90-day VTE after fast-track THA and TKA (BMI, age, and history of VTE) as fixed effects and department as a random effect.
Results: Of the 16,267 procedures (39.1% males, mean age 67.9 (SD 10.0) years, median LOS 2 [IQR 2-3]) 12.518 (77.0%) were performed using a tourniquet (median duration 60 [51-70] min). The annual tourniquet usage varied greatly between departments from 0 % to 100%, but also within departments from 99% to 0%. The 90-day incidence of VTE was 77 (0.47%) without significant difference with or without tourniquet 52 (0.42%) vs 25 (0.67%) (p=0.056), respectively. This association remained insignificant with OR 0.62 (95% CI: 0.38-1.01, p=0.054) after adjustment for previously identified risk-factors.
Interpretation / Conclusion: The use of tourniquet was not associated to increased 90-day VTE risk after fast-track TKA. However, further investigations on the unexpected insignificant tendency of a protective effect of tourniquet is warranted.