Aseptic revision total knee arthroplasty outcomes were equivalent to patients' own pre-failure state but inferior to patients without revision.

PURPOSE: The purpose of this study was to (1) longitudinally compare the patient-reported outcome measures (PROMs) of the same patients who underwent primary TKA and revision TKA, and (2) compared the results of these revision TKA with a matched cohort of well-functioning primary TKA. The hypothesis was revision TKA could result in equivalent outcomes to patients' own primary TKA or the primary TKA of patients who did not require revision. METHODS: Prospectively collected data of 123 patients who underwent primary TKA and subsequently aseptic revision TKA ("revised group"), were matched using nearest-neighbor method to 123 well-functioning primary TKA that did not require revision ("control group"). Preoperative (prior to primary TKA), at time of failure (prior to revision TKA), postoperative 6-month and 2-year PROMs included Knee Society scores (KSS), Oxford Knee Score (OKS) and Short Form-36 (SF-36). Minimal clinically important difference (MCID) attainment was analyzed. Wilcoxon and McNemar's tests were used to compare outcomes within the revised group (primary vs revision), Mann-Whitney U test and Chi-Square test for the revised and control groups. RESULTS: The revised group had poorer KSS objective (p = 0.045), KSS functional (p < 0.001), OKS (p = 0.011) and SF-36 PCS (p < 0.001) at time of failure (prior to revision TKA), compared to their preoperative PROMs (prior to primary TKA). Revision TKA resulted in restoration of KSS objective, OKS and SF-36 PCS (NS) that were equivalent to their primary TKA, but poorer KSS functional (p < 0.050). Patients in the revised group had a lower proportion of MCID attainment in KSS objective (p = 0.014) and OKS (p < 0.001) at 2-year after primary TKA when compared to the control group. Revision TKA also led to poorer KSS objective, KSS functional and SF-36 PCS (p < 0.050) when compared to primary TKA of the control group. CONCLUSION: Outcomes following aseptic revision were equivalent to patients' own pre-failure state but inferior to patients with non-revised implants. An individualized approach toward goal setting and assessing adequacy of aseptic revision TKA can be adopted based on patients' pre-failure outcomes. LEVEL OF EVIDENCE: III.

Defining the minimal clinically important difference for the knee society score following revision total knee arthroplasty.

BACKGROUND: No previous study has evaluated the MCID for revision total knee arthroplasty (TKA). This study aimed to identify the MCID for the Knee Society Score (KSS), for revision TKA. METHODS: Prospectively collected data from 270 patients who underwent revision TKA at a single institution was analysed. Clinical assessment was performed preoperatively, at 6 months and 2 years using Knee Society Function Score (KSFS) and Knee (KSKS) Scores, and Oxford Knee Score (OKS). MCID was evaluated with a three-pronged methodology, using (1) anchor-based method with linear regression, (2) anchor-based method with receiver operating characteristic (ROC) and area under curve (AUC), (3) distribution-based method with standard deviation (SD). The anchors used were improvement in OKS ≥ 5, patient satisfaction, and implant survivorship following revision TKA. RESULTS: The cohort comprised 70% females, with mean age of 69.0 years, that underwent unilateral revision TKA. The MCID determined by anchor-based linear regression method using OKS was 6.3 for KSFS, and 6.6 for KSKS. The MCID determined by anchor-based ROC was between 15 and 20 for KSFS (AUC: satisfaction = 71.8%, survivorship = 61.4%) and between 33 and 34 for KSKS (AUC: satisfaction = 76.3%, survivorship = 67.1%). The MCID determined by distribution-based method of 0.5 SD was 11.7 for KSFS and 11.9 for KSKS. CONCLUSION: The MCID of 6.3 points for KSFS, and 6.6 points for KSKS, is a useful benchmark for future studies looking to compare revision against primary TKA outcomes. Clinically, the MCID between 15 and 20 for KSFS and between 33 and 34 for KSKS is a powerful tool for discriminating patients with successful outcomes after revision TKA. Implant survivorship is an objective and naturally dichotomous outcome measure that complements the subjective measure of patient satisfaction, which future MCID studies could consider utilizing as anchors in ROC. LEVEL OF EVIDENCE: II.

Posterior condylar offset and posterior tibial slope targets to optimize knee flexion after unicompartmental knee arthroplasty.

PURPOSE: To evaluate the relationship between posterior tibial slope (PTS), posterior condylar offset (PCO), femoral sagittal angle (FSA) on clinical outcomes, and propose optimal sagittal plane alignments for unicompartmental knee arthroplasty (UKA). METHODS: Prospectively collected data of 265 medial UKA was analysed. PTS, PCO, FSA were measured on preoperative and postoperative lateral radiographs. Clinical assessment was done at 6-month, 2-year and 10-year using Oxford Knee Score, Knee Society Knee and Function scores, Short Form-36, range of motion (ROM), fulfilment of satisfaction and expectations. Implant survivorship was noted at mean 15-year. Kendall rank correlation test evaluated correlations of sagittal parameters against clinical outcomes. Multivariable linear regression evaluated predictors of postoperative ROM. Effect plots and interaction plots were used to identify angles with the best outcomes. (p < 0.05) was the threshold for statistical significance. RESULTS: There were significant correlations between PTS, PCO and FSA. Younger age, lower BMI, implant type, greater preoperative flexion, steeper PTS and preservation of PCO were significant predictors of greater postoperative flexion. There were significant interaction effects between PTS and PCO. Effect plots demonstrate a PTS between 2° to 8° and restoration of PCO within 1.5 mm of native values are optimal for better postoperative flexion. Interaction plot reveals that it is preferable to reduce PCO by 1.0 mm when PTS is 2° and restore PCO at 0 mm when PTS is 8°. CONCLUSION: UKA surgeons and future studies should be mindful of the relationship between PTS, PCO and FSA, and avoid considering them in isolation. When deciding on the method of balancing component gaps in UKA, surgeons should rely on the PTS. Decrease the posterior condylar cut when PTS is steep, and increase the posterior condylar cut when PTS is shallow. The acceptable range for PTS is between 2° to 8° and PCO should be restored to 1.5 mm of native values. LEVEL OF EVIDENCE: II.

The oxford knee score minimal clinically important difference for revision total knee arthroplasty.

BACKGROUND: Minimal clinically important difference (MCID) is crucial for interpreting meaningful improvements in patient-reported outcome measures (PROMs). No previous study has evaluated the MCID for the Oxford Knee Score (OKS) in revision total knee arthroplasty (TKA). This study aimed to propose the OKS MCID for revision TKA. METHODS: Prospectively collected data from 191 patients who underwent revision TKA at a single institution was analysed. Clinical assessment was performed preoperatively and at 2 years using OKS and Short-Form 36 Physical Component Score (SF-36 PCS). MCID was evaluated with a three-pronged methodology, using (1) anchor-based method with linear regression, (2) anchor-based method with receiver operating characteristic (ROC) and area under curve (AUC), (3) distribution-based method with standard deviation (SD). The anchors used were improvement in SF-36 PCS ≥ 12, patient satisfaction, and implant survivorship following revision TKA. RESULTS: The MCID determined by anchor-based linear regression method using improvements in SF-36 PCS was 4.9 points. The MCID determined by anchor-based ROC was 10.5 points for satisfaction (AUC = 74.8%) and 13.5 points for implant survivorship (AUC = 73.7%). The MCID determined by distribution-based method of 0.5 SD was 4.7. CONCLUSION: The proposed MCID for OKS following revision TKA is 4.9 points. Patients who achieve an improvement in OKS of at least 10.5-13.5 points by 2 years are likely to be satisfied with their surgery and not require a subsequent re-revision TKA. Patients undergoing revision TKA should aim for an improvement in OKS of at least 10.5-13.5 points as a target score.

Behavioral impact of national health campaigns on healthy lifestyle practices among young adults in Singapore: a cross-sectional study.

BACKGROUND: National health campaigns are often used to improve lifestyle behaviors in the general population. However, evidence specifically in the young adult population is scarce. Given the general deterioration of healthy lifestyle practices from adolescence to young adulthood, it is imperative to study this age group. This study aimed to investigate the behavioral impact of a national health campaign in Singapore on the lifestyle practices of young adults, and whether sex or full-time working and schooling status affected lifestyle practices. METHODS: A total of 594 Singaporean respondents aged 18-39 years old were interviewed via a cross-sectional study in December 2019. Lifestyle practices assessed were diet, exercise, alcohol consumption, current tobacco use, and participation in health screening programs. Other factors investigated included exposure to the national health campaign "War on Diabetes" (WoD), sex, ethnicity, and working/schooling status. Multivariable modified Breslow-Cox proportional hazards models were used to estimate prevalence risk ratios (PRRs) as measures for the associations in this study, after adjusting for potential confounders. RESULTS: Exposure to the WoD campaign had a significant association with meeting dietary recommendations (PRR = 1.6, 95% CI: 1.0-2.5, p = 0.037), participation in screening (PRR = 1.2, 95% CI: 1.0-1.5, p = 0.028), and current tobacco use (PRR = 0.5, 95% CI: 0.3-0.8, p = 0.003). Males were significantly more likely to meet exercise recommendations (PRR = 2.0, 95% CI: 1.5-2.7, p < 0.001), currently use tobacco (PRR = 3.9, 95% CI: 2.2-6.9, p < 0.001), and consume alcohol excessively (PRR = 1.5, 95% CI: 1.0-2.3, p = 0.046), as compared to females. Working young adults were significantly less likely to meet exercise recommendations (PRR = 0.7, 95% CI: 0.5-0.9, p = 0.019) but significantly more likely to be current tobacco users (PRR = 1.8, 95% CI: 1.1-3.1, p = 0.024), as compared to those who were in school. CONCLUSIONS: While this paper affirms that national health campaigns have significant beneficial associations in diet, health screenings and current tobacco use, policymakers should acknowledge that young adults are an age group with different influences that impact their healthy lifestyle habits. Specific interventions that target these subgroups may be required for better health outcomes. Future studies should evaluate other socio-environmental factors that could play a role in modifying the effect of health campaigns among young adults.

A Weighted Scoring System Based on Preoperative and Long-Term Patient-Reported Outcome Measures to Guide Timing of Knee Arthroplasty.

BACKGROUND: There is currently no existing consensus regarding timing of knee arthroplasty. This study aimed to develop a weighted scoring system from patient-reported outcome measures (PROMs) to guide timing of knee arthroplasty based on preoperative severity and long-term effectiveness. METHODS: Prospectively collected data of 766 total knee arthroplasties (TKAs) and 382 unicompartmental knee arthroplasties (UKAs) at a single institution were analyzed. PROMs were assessed preoperatively and at 10 years using the Knee Society Score (KSS), Oxford Knee Score (OKS), and Short Form-36 physical component score (SF-36 PCS). Receiver operating characteristic analysis identified thresholds where preoperative PROMs predicted 10-year clinically meaningful improvements (minimal clinically important difference [MCID]). Threshold weights were assigned to PROMs based on their ability to predict MCID in isolation or in combination. RESULTS: Poorer baseline PROMs predicted 10-year MCID attainments. The threshold of 49.5 points for the KSS, 30.5 points for the OKS, and 40.7 points for the SF-36 PCS and 55.5 points for the KSS, 33.5 points for the OKS, and 40.5 points for the SF-36 PCS was weighted 1 point for predicting MCID in 1 PROM for TKA and UKA, respectively. The threshold of 33.4 and 33.9 points for the SF-36 PCS was weighted 2 points for predicting MCID in 2 PROMs, whereas 29.3 and 31.3 points for the SF-36 PCS were weighted 3 points for predicting MCID in 3 PROMs for TKA and UKA, respectively. The sum of weighted components from 0 (lowest) to 5 (highest) represented likelihood for long-term benefits at 10 years. CONCLUSION: This scoring system is a useful clinical adjunct for deciding timing of knee arthroplasty and prioritizing patients in institutions with long waitlists. LEVEL OF EVIDENCE: II.

No difference in long-term outcomes between men and women undergoing medial fixed-bearing cemented unicompartmental knee arthroplasty: A retrospective cohort study with minimum 10-year follow up.

BACKGROUND: Some studies have suggested that women have poorer short-term outcomes after unicompartmental knee arthroplasty (UKA) due to a higher incidence of implant overhang. This study aimed to compare patient-reported outcome measures (PROMs) between men and women after UKA at a minimum follow-up of 10 years. METHODS: Patients who underwent medial fixed-bearing UKA by two arthroplasty surgeons were identified from an institutional joint registry. Men and women were matched for age, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists class, range-of-motion and baseline PROMs using propensity scores. PROMs were compared at 2 and 10 years. Patients also completed a satisfaction questionnaire during these visits. Radiographic outliers were defined as > 2 mm of overhang. RESULTS: A total of 128 patients were included. There was no difference in complications, length of stay or readmissions. Women had poorer Knee Society functional scores, Short-Form 36 physical and mental component scores (SF-36 MCS) at 2 years. No difference in PROMs was found at 10 years, except for poorer SF-36 MCS in women (P = 0.041). At 10 years, 96% of women and 92% of men were satisfied (P = 0.243). Fifteen-year survivorship free from any revision was 96% in each group. There were more medial-tibial outliers in women (9%) compared with men (5%) (P = 0.018). However, no association between outliers and outcomes or survivorship was found on multivariate analyses. CONCLUSION: There was nodifference in clinical outcomes between men and women undergoing UKA at a minimum follow-up of 10 years. While women had a higher incidence of medial tibial overhang, this was not associated with long-term outcomes or survivorship.

Preoperative Mental Health Influences Patient-Reported Outcome Measures and Satisfaction After Revision Total Knee Arthroplasty.

BACKGROUND: A higher prevalence of mental health conditions has been reported in patients undergoing revision total knee arthroplasty (rTKA). This study investigated the effect of preoperative mental health on patient-reported outcome measures (PROMs) and satisfaction after rTKA. METHODS: A total of 245 patients who underwent rTKA in 2004-2018 were identified from our institutional joint registry. The most common indications were aseptic loosening (n = 111), infection (n = 70), and instability (n = 35). 36-item Short-Form health survey (SF-36) mental component summary (MCS) was used to stratify the cohort into: Low-MCS (SF-36 MCS <50; n = 112) and control (SF-36 MCS ≥50; n = 133) groups. Knee Society score, Oxford knee score, SF-36 physical score, and a satisfaction questionnaire were used to compare the low-MCS and control at 6 months and 2 years. RESULTS: All PROMs were poorer in the low-MCS group at 6 months and 2 years. However, both groups demonstrated a comparable improvement in each PROM and a similar proportion attained the minimal clinically important difference. Fewer patients in the low-MCS group were satisfied at 2 years (72.2% vs 84.5%, P = .045). Lower preoperative SF-36 MCS was independently associated with increased odds of dissatisfaction (OR 1.037, 95% CI 1.004-1.070, P = .027). Although the change in SF-36 MCS was greater in the low-MCS group, the final value remained lower at 2 years. CONCLUSION: While patients with poor mental health had inferior PROMs preoperatively and postoperatively, a similar percentage experienced a clinically meaningful improvement at 2 years. Perioperative optimization of psychological factors should still be emphasized as these patients were at a higher risk of dissatisfaction after rTKA.

Change in Body Mass Index after Simultaneous Bilateral Total Knee Arthroplasty: Risk Factors and Its Influence on Functional Outcomes.

BACKGROUND: Previous studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA. METHODS: Prospectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes. RESULTS: At 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05). CONCLUSION: Up to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes. LEVEL OF EVIDENCE: III, therapeutic study.

The effect of tibial and femoral component coronal alignment on clinical outcomes and survivorship in unicompartmental knee arthroplasty.

AIMS: This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. METHODS: Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups. RESULTS: Significant two-way interaction effects between TCCA and FCCA were identified. Adjusted for each other and their interaction, a TCCA of between 2° and 4° and a FCCA of between 0° and 2° were found to be associated with the greatest improvements in knee scores and the probability of fulfilling expectations and satisfaction at ten years. Patients in the optimal group whose TCCA and FCCA were between 2° and 4°, and 0° and 2°, respectively, had a significant survival benefit at 15 years compared with the non-optimal group (optimal: survival = 100% vs non-optimal: survival = 92%, 95% confidence interval (CI) 88% to 96%). CONCLUSION: Significant two-way interactions between the TCCA and FCCA demonstrate the importance of evaluating the alignment of the components concomitantly in future studies. By doing so, we found that patients who concomitantly had both a TCCA of between 2° and 4° and a FCCA of between 0° and 2° had the best patient-reported outcome measures at ten years and better survivorship at 15 years. Cite this article: Bone Joint J 2021;103-B(2):338-346.

Coronal Alignment of Fixed-Bearing Unicompartmental Knee Arthroplasty Femoral Component May Affect Long-Term Clinical Outcomes.

BACKGROUND: This study aims to investigate the clinical effects of femoral component coronal alignment in a cohort of fixed-bearing unicompartmental knee arthroplasty with clinical and radiological follow-up of 10 years. METHODS: Prospectively collected registry data of 264 consecutive, cemented, primary fixed-bearing medial unicompartmental knee arthroplasties performed at a single institution from 2004 to 2007 were reviewed. Femoral component coronal angle (FCCA), tibial component coronal angle, and hip-knee-ankle angle were measured on postoperative radiographs. Patients were grouped into acceptable (AG ≤ 3°) and outlier (OG > 3°) groups according to absolute FCCA. Clinical assessment at 6-month, 2-year, and 10-year follow-up was performed using Knee Society Knee and Function Scores, Oxford Knee Score (OKS), and Short Form-36. Fulfillment of expectations, satisfaction, and implant survivorship was recorded. RESULTS: There was no significant difference in demographics, tibial component coronal angle, hip-knee-ankle angle, and sagittal parameters in both groups. The OG had poorer OKS at 10 years and a larger deterioration from 2 to 10 years compared to AG (P = .02). Increase in FCCA was associated with deterioration in 2-year OKS (adjusted ß = 0.23, P = .01), 10-year OKS (adjusted ß = 0.26, P = .03), and 2-year Short Form-36 physical component score (adjusted ß = -0.44, P = .01). Expectation fulfillment at 2 years was lower in the OG vs the AG (88% vs 100%, P = .03). Both groups had similar 10-year survivorship (99% vs 98%, P = .65). CONCLUSIONS: FCCA may affect long-term clinical outcomes, but not short-term clinical outcomes nor 10-year survivorship. Given similar limb alignment, coronal and sagittal component positioning, a larger FCCA was associated with poorer outcomes at 10-year follow-up.