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Background: Radiostereometric analysis (RSA) provides highly accurate data about themigration of a total knee arthroplasty (TKA) component. However, patient-reported outcome measures (PROMs) reflect the patients' perspective of their functional status, pain, and overall health after TKA. The aimof this study was to evaluate the association between tibial implant migration and change in postoperative PROMs and clinical scores, using data pooled from long-term follow-up RSA studies. Methods: Individual implantmigration data were collected from 5 randomized RSA studies, including a total of 300 patients with 6 distinct TKA implant designs (all Stryker). Tibial implant migration (maximumtotal pointmotion [MTPM]) was evaluated with RSA at 3months, 1 year, and 2, 5, 7, and 10 years postoperatively. The Knee Society Score (KSS)-Knee and KSS-Function and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales were collected in all studies at the same follow-up times. Linear mixed-effects models, with adjustment for TKA implant design and patient characteristics, were used to analyze the data. The 3-month follow-up visit was used as the baseline to assess the association between implant migration and PROMs across the 10-year follow-up. Results: No association between tibial implant migration and change in KSS-Knee (p = 0.384), KSS-Function (p = 0.737), KOOS-Symptoms (p = 0.398), KOOS-Pain (p = 0.699), KOOS-Activities of Daily Living (p = 0.205), KOOS-Sport and Recreation (p = 0.702), or KOOS-Quality of Life (p = 0.368) was found across the entire follow-up. Similar results were found when using the 2-year follow-up as the baseline, after which both cemented and uncemented implants are expected to have stabilized. Conclusions: Tibial baseplate migration was not associated with postoperative worsening in PROMs or clinical scores in patients who underwent TKA. These findings suggest that implant migration, as measured with RSA, measures a different parameter (i.e., implant-bone fixation) than PROMs (i.e., patient perception) and clinical scores. Therefore, to assess the performance and safety of TKA implant designs, RSA and PROMs cannot be used interchangeably during the postoperative follow-up of patients and evaluation of the fixation of knee implants. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background and purpose -- In total knee arthroplasty (TKA), metal-backed (MBT) and all-polyethylene (APT) designs have shown comparable implant migration up to 2 years postoperatively using radiostereometric analysis (RSA). However, studies comparing mid-term migration of both designs are lacking. Furthermore, continuously migrating TKAs up to 2 years may continue to migrate or stabilize thereafter. Therefore, we compared 5-year migration of MBT and APT using either cruciate-stabilizing (CS) or posteriorstabilizing (PS) designs and specifically assessed migration profiles of continuously migrating TKAs beyond 2 years. Patients and methods -- The present study includes results from 2 randomized trials comparing migration of cemented MBT with APT of either CS (CS study, n = 59) or PS (PS study, n = 56) design. 2 surgeons performed all surgeries. We used a linear mixed model for the analyses. Results -- The overall migration between MBT and APT TKAs was similar for either the CS or PS design over a 5-year period. In both studies combined, 9 implants showed continuous migration in the second postoperative year, of which 1 (APT-CS) was revised for instability, 4 (2 MBT-CS, MBT-PS, APT-PS) stabilized, and 4 (2 MBT-CS, APT-CS, MBT-PS) lacked 5-year data. Interpretation -- Overall migration was similar between MBT and APT TKAs up to 5 years, for both the CS and PS design. 4 initially migrating TKAs stabilized between 2- and 5-year follow-up, stressing the need for longer-term followup to determine whether second-year continuous migration correctly predicts loosening. [ABSTRACT FROM AUTHOR]

Abstract Background The association between knee alignment and knee pain in knee osteoarthritis (OA) is unclear. High tibial osteotomy, a treatment option in knee OA, alters load from the affected to the unaffected compartment of the knee by correcting malalignment. This surgical procedure thus offers the possibility to study the cross-sectional and longitudinal association of alignment to pain. The aims were to study 1) the preoperative association of knee alignment to preoperative knee pain and 2) the association of change in knee alignment with surgery to change in knee pain over time in patients operated on for knee OA by high tibial osteotomy. Methods 182 patients (68% men) mean age 53 years (34 - 69) with varus alignment having tibial osteotomy by the hemicallotasis technique for medial knee OA were consecutively included. Knee alignment was assessed by the Hip-Knee-Ankle (HKA) angle from radiographs including the hip and ankle joints. Knee pain was measured by the subscale pain (0 - 100, worst to best scale) of the Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively and at one year follow-up. To estimate the association between knee alignment and knee pain multivariate regression analyses were used. Results Mean preoperative varus alignment was 170 degrees (153 - 178) and mean preoperative KOOS pain was 42 points (3 - 86). There was no association between preoperative varus alignment and preoperative KOOS pain, crude analysis 0.02 points (95% CI -0.6 - 0.7) change in pain with every degree of HKA angle, adjusted analysis 0.3 points (95% CI -1.3 - 0.6). The mean postoperative knee alignment was 184 degrees (171 - 185). The mean change in knee alignment was 13 degrees (0 - 30). The mean change in KOOS pain was 32 (-16 - 83). There was neither any association between change in knee alignment and change in KOOS pain over time, crude analysis 0.3 point (95% CI -0.6 - 1.2), adjusted analysis 0.4 points (95% CI 0.6 - 1.4). Conclusion We found no association between knee alignment and knee pain in patients with knee OA indicating that alignment and pain are separate entities, and that the degree of preoperative malalignment is not a predictor of knee pain after high tibial osteotomy.

Abstract Background Tibial osteotomy is a treatment for younger and/or physically active patients suffering from uni-compartmental knee osteoarthritis. The open wedge osteotomy by the hemicallotasis technique includes the use of external fixation. The use of external fixation has several advantages, as early mobilization and the opportunity for optimal correction. However, the hemicallotasis technique has also been described as a cumbersome procedure for the patient. The aim of this study was to prospectively evaluate patient-relevant outcomes during the first 2 post-operative years. Especially the treatment period, during which external fixation was used, was closely monitored. Methods In an uncontrolled study, fifty-eight consecutive patients, 30 men and 28 women (mean age 54 years) were operated on by the hemicallotasis technique were evaluated with the patient-relevant outcome measure Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively, during the treatment with external fixation, one week after removal of the external fixation, at 6 months, and at one and two years postoperatively. Results At the 2-year postoperative follow-up, all subscales of the KOOS were improved (p < 0.001), mostly in pain (41–80 on a 0–100 worst to best scale) and knee-related quality of life (21–61 on a 0–100 worst to best scale), compared to the preoperative status. Significant improvements in pain and other symptoms, function of daily life and quality of life were seen already during the treatment period (mean 98 ± 18 days) with the external fixation. More demanding functions such as kneeling, squatting, jumping and running, were improved first after extraction of the external fixation device and the pins. Conclusion Tibial osteotomy by the hemicallotasis technique yields large improvement in self-rated pain, function and quality of life, which persists over two years. Surprisingly, large improvements occurred already during the immediate post-operative period when the external fixation was still used.

Abstract Background The Knee injury and Osteoarthritis Outcome Score (KOOS) is an extension of the Western Ontario and McMaster Universities Osteoarthrtis Index (WOMAC), the most commonly used outcome instrument for assessment of patient-relevant treatment effects in osteoarthritis. KOOS was developed for younger and/or more active patients with knee injury and knee osteoarthritis and has in previous studies on these groups been the more responsive instrument compared to the WOMAC. Some patients eligible for total knee replacement have expectations of more demanding physical functions than required for daily living. This encouraged us to study the use of the Knee injury and Osteoarthritis Outcome Score (KOOS) to assess the outcome of total knee replacement. Methods We studied the test-retest reliability, validity and responsiveness of the Swedish version LK 1.0 of the KOOS when used to prospectively evaluate the outcome of 105 patients (mean age 71.3, 66 women) after total knee replacement. The follow-up rates at 6 and 12 months were 92% and 86%, respectively. Results The intraclass correlation coefficients were over 0.75 for all subscales indicating sufficient test-retest reliability. Bland-Altman plots confirmed this finding. Over 90% of the patients regarded improvement in the subscales Pain, Symptoms, Activities of Daily Living, and knee-related Quality of Life to be extremely or very important when deciding to have their knee operated on indicating good content validity. The correlations found in comparison to the SF-36 indicated the KOOS measured expected constructs. The most responsive subscale was knee-related Quality of Life. The effect sizes of the five KOOS subscales at 12 months ranged from 1.08 to 3.54 and for the WOMAC from 1.65 to 2.56. Conclusion The Knee injury and Osteoarthritis Outcome Score (KOOS) is a valid, reliable, and responsive outcome measure in total joint replacement. In comparison to the WOMAC, the KOOS improved validity and may be at least as responsive as the WOMAC.