Severe genu varus deformity does not affect enhanced recovery after surgery total knee arthroplasty outcomes.

INTRODUCTION: Enhanced recovery after surgery (ERAS) has been increasingly adopted in orthopaedic surgery. Although not an exclusion criterion, patients undergoing total knee arthroplasty (TKA) with preoperative severe varus deformity may be less likely to be enrolled for ERAS. This study aimed to compare the success of ERAS TKA between patients with severe preoperative varus deformities (≥ 15° varus) and the control group (< 15° varus to 14° valgus). Our secondary aim was to compare postoperative complications and functional outcomes between the two groups. MATERIALS & METHODS: 310 TKAs performed from August 2019 to February 2021 were analyzed with a follow-up of 6 months postoperatively. The primary outcome, ERAS TKA success, was defined as length of hospital stay of < 24 h. Other parameters included 30-day postoperative complications and clinical outcomes such as the original Oxford Knee Score (OKS), the Knee Society Knee (KSKS) and Function Score (KSFS), Visual Analog Scale for Pain (VAS-P), 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS) and SF-36 Mental Component Summary (MCS). RESULTS: There were 119 patients in the severe deformity group and 191 patients in the control group. There were no significant differences in ERAS success between the severe deformity group and control group, with both groups achieving similarly high rates (> 90%) of ERAS success. There were also no differences in 30-day postoperative complications and 6-month postoperative clinical outcomes. CONCLUSION: Patients with severe preoperative varus deformity undergoing ERAS TKA achieved high ERAS success rates (> 90%). Genu varum is not a contraindication for ERAS TKA.

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.

The patient acceptable symptom state for the knee society score, oxford knee score and short form-36 following unicompartmental knee arthroplasty.

PURPOSE: The patient acceptable symptom state (PASS) is a target value on a patient-reported outcome measures (PROM) scale beyond which patients deem themselves to have attained an acceptable outcome. This study aimed to define the PASS thresholds for generic and knee-specific PROMs at 2 years after unicompartmental knee arthroplasty (UKA). METHODS: Prospectively collected data of 955 patients who underwent UKA for medial osteoarthritis at a single institution was reviewed. Patients were assessed preoperatively and 2 years postoperatively using the Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), SF-36 Physical Component Score (PCS) and Mental Component Score (MCS). Responses to an anchor question assessing patients' overall rating of treatment results were dichotomized and used to determine if PASS was achieved. PASS thresholds for each PROM were selected based on the Youden index on a receiver operating characteristics (ROC) curve. Sensitivity analyses were performed for different subgroups (by age, gender, BMI), baseline score tertiles and an alternate definition of PASS. RESULTS: In total, 92.7% reported their current state as acceptable. The areas under the curve (AUC) for ROCs were 0.72-0.83, except for the SF-36 PCS (AUC 0.64), indicating good discriminative accuracy of the other PROMs. PASS thresholds were 85.5 for KSKS, 77.5 for KSFS, 41.5 for OKS, 49.9 for SF-36 PCS and 54.6 for SF-36 MCS. Sensitivity analyses revealed that the thresholds were robust. Patients who attained a PASS were at least 4-5 times more likely to be satisfied and have expectations fulfilled. CONCLUSION: PASS thresholds can be used to define treatment success in future outcome studies. At the individual level, they provide clinically relevant benchmarks for surgeons when assessing postoperative recovery. LEVEL OF EVIDENCE: III.

Clinical Frailty Scale is a better predictor for adverse post-operative complications and functional outcomes than Modified Frailty Index and Charlson Comorbidity Index after total knee arthroplasty.

PURPOSE: Studies have demonstrated correlations between frailty and comorbidity scores with adverse outcomes in total knee replacement (TKR). However, there is a lack of consensus on the most suitable pre-operative assessment tool. This study aims to compare Clinical Frailty Scale (CFS), Modified Frailty Index (MFI), and Charlson Comorbidity Index (CCI) in predicting adverse post-operative complications and functional outcomes following a unilateral TKR. METHODS: In total, 811 unilateral TKR patients from a tertiary hospital were identified. Pre-operative variables were age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) class, CFS, MFI, and CCI. Binary logistic regression analysis was performed to ascertain odd ratios of pre-operative variables on adverse post-operative complications (length of stay < LOS >, complications, ICU/HD admission, discharge location, 30-day readmission, 2-year reoperation). Multiple linear regression analyses were used to estimate the standardized effects of pre-operative variables on the Knee Society Functional Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), and 36-Item Short Form Survey (SF-36). RESULTS: CFS is a strong predictor for LOS (OR 1.876, p < 0.001), complications (OR 1.83-4.97, p < 0.05), discharge location (OR 1.84, p < 0.001), and 2-year reoperation rate (OR 1.98, p < .001). ASA and MFI were predictors for ICU/HD admission (OR:4.04, p = 0.002; OR 1.58, p = 0.022, respectively). None of the scores was predictive for 30-day readmission. A higher CFS was associated with a worse outcome for 6-month KSS, 2-year KSS, 6-month OKS, 2-year OKS, and 6-month SF-36. CONCLUSION: CFS is a superior predictor for post-operative complications and functional outcomes than MFI and CCI in unilateral TKR patients. This suggests the importance of assessing pre-operative functional status when planning for TKR. LEVEL OF EVIDENCE: Diagnostic, II.

Cost-Effectiveness of Robot-Assisted Total Knee Arthroplasty: A Markov Decision Analysis.

BACKGROUND: Robot-assisted total knee arthroplasty (rTKA) may improve clinical outcomes for patients who have end-stage osteoarthritis of the knee. However, the costs of rTKA are high, and there is a paucity of data evaluating the cost-effectiveness of rTKA. We aimed to analyze the cost per quality-adjusted life-year (QALY) of rTKA relative to manual TKA. METHODS: A Markov decision analysis was performed using known parameters for costs, outcomes, implant survivorships, and mortalities. The cost-effectiveness of rTKA relative to manual TKA was assessed for end-stage knee osteoarthritis patients who had a mean age of 65 years (range, 27 to 94 years). The rTKA costs were calculated for a pay-per-use contract robot. RESULTS: Using the Markov Model with an annual case volume of 500 patients and a mean age of 65 years, the overall health gain per patient was 13.34 QALYs after rTKA and 13.31 QALYs after manual TKA. This resulted in an overall gain in QALYs of 0.03 for each patient undergoing an rTKA compared with manual TKA and an incremental cost of $128,526 Singapore Dollars per QALY. CONCLUSION: Robotic TKA is not a cost-effective alternative to conventional TKA using a pay-per-use contract robot.

Novel morphogenic knee implant delivers comparable mid-term outcomes as compared to conventional non-morphogenic implants.

INTRODUCTION: Conventional total knee arthroplasty (C-TKA) implants have well-established mid- and long-term outcomes. The novel TKA (N-TKA) implants provide morphogenic implant components with smaller size increments to facilitate anatomical replication. The aim of the study is to evaluate if these advantages provides better clinical outcomes. MATERIALS AND METHODS: Registry data prospectively collected within a single institution from 2014 to 2018 was reviewed and propensity score matching was performed to match C-TKA to N-TKA. 70 pairs of cruciate retaining (CR) TKA and 116 pairs of posterior stabilized (PS) TKA were identified. Range of motion, SF-36, Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS) and Oxford Knee Score (OKS) were assessed preoperatively, 6 and 24 months postoperatively. Satisfaction was assessed 6 and 24 months postoperatively. Independent T test was performed for parametric data, whereas Wilcoxon rank-sum analysis was performed for non-parametric data. RESULTS: Both C-TKA and N-TKA cohorts demonstrated statistically significant improvement for KSKS, KSFS, OKS and SF-36 at 6 and 24 months postoperatively. C-TKA CR patients had better flexion at 6 months as compared to N-TKA CR (108.7° versus 98.3°, respectively, p = 0.046). At 24 months, there was no difference between C-TKA and N-TKA for range of motion, KSKS, KSFS, OKS and SF-36 PCS, regardless of insert type (p > 0.05). CONCLUSIONS: Both models showed great postoperative improvements in KSFS, KSKS, OKS and SF-36 and have comparable early and mid-term outcomes, suggesting that N-TKAs are suitable substitutes for C-TKA. Longer follow-up studies are required to evaluate the long-term outcomes of N-TKAs. LEVEL OF EVIDENCE: lll.

The effect of topical tranexamic acid on functional outcomes and quality of life in patients undergoing unicompartmental knee arthroplasty.

INTRODUCTION: Tranexamic acid (TXA) is being increasingly utilized to reduce blood loss after knee joint arthroplasty. However, there is a lack of studies on the effect of topical TXA on the functional outcomes and quality of life after Unicompartmental Knee Arthroplasty (UKA). The aim of this study was to determine the effect of topical TXA on functional outcomes and quality of life scores in patients undergoing UKA. MATERIALS AND METHODS: We retrospectively analysed patients undergoing unilateral UKA at a single tertiary hospital from 2005 to 2017. Patients were divided into 2 groups: (1) The control group which did not receive TXA (n = 742); (2) The TXA group which received topical TXA (n = 331). Functional outcomes were assessed using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS), while quality of life was evaluated with the Physical Component Score (PCS) and Mental Component Score (MCS) of Short-Form 36 (SF-36) preoperatively and at 6 months and 2 years follow-up. RESULTS: At 6 months and 2 years post-surgery, there were no significant differences in the functional scores between the groups. The number of patients who attained minimum clinically important difference (MCID) for each of the functional scores was also comparable between the groups. CONCLUSIONS: In patients undergoing UKA, functional outcomes and quality of life scores were comparable between those who received topical TXA and those who did not. There was no significant improvement or impairment in knee function associated with topical TXA administration in UKA up to 2 years follow-up.

No differences in 10-year clinical outcomes and quality of life between patients with different mediolateral femoral component positions in fixed-bearing medial unicompartmental knee arthroplasty.

PURPOSE: There has been a paucity of literature evaluating the role of mediolateral femoral component position (FCP) in medial unicompartmental arthroplasty (UKA). Hence, the aim of this study is to evaluate whether the mediolateral FCP in UKA will affect the 10-year clinical outcomes and quality of life of patients who underwent medial UKA. METHODS: Data of 262 patients who underwent medial UKA were analyzed. All patients were assessed at 6 months, 2 years and 10 years using the Knee Society Function Score, Knee Society Knee Score, Oxford Knee Score, Short-Form 36 Physical/Mental Component Scores and postoperative satisfaction. The mediolateral FCP on postoperative radiographs was measured by independent assessors using the Picture Archiving and Communication Systems. 144 patients were distributed into group C (center), 98 into group M (medial) and 20 into group L (lateral) according to FCP, and one-way ANOVA was used to compare the functional outcomes of the three groups. RESULTS: No statistical differences were found between the three groups in terms of 10-year clinical outcomes, quality of life, satisfaction rates and revision rates. CONCLUSION: Differences in mediolateral FCP did not result in significant difference in 10-year postoperative clinical outcomes for patients who underwent fixed-bearing medial UKAs. LEVEL OF EVIDENCE: Retrospective study, Level 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.

All-polyethylene unicompartmental knee arthroplasty is associated with increased risks of poorer knee society knee score and lower satisfaction in obese patients.

BACKGROUND: Although metal-backed tibial component (MB) is biomechanically superior to all-polyethylene (AP) implants in fixed-bearing unicompartmental knee arthroplasty (UKA), recent studies have shown comparable functional outcomes between the two. However, no study has examined this comparison in obese patients (BMI ≥ 30 kg/m2). We investigated whether functional outcomes between the two implants differ among obese patients, and whether the extent of obesity influences these outcomes. PATIENTS AND METHODS: Four hundred twenty-two UKA implants from 347 obese patients were reviewed retrospectively. Patients were assessed using the Knee Society Knee Score (KSKS) and Function Score (KSFS), the original Oxford Knee Score (OKS), and SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS). Minimal clinically important difference (MCID) attainment was recorded. Patients' fulfillment of expectations and satisfaction with the surgery outcome was also graded. Patients were further divided into lower obesity (BMI 30-34.9 kg/m2) and higher obesity (BMI ≥ 35 kg/m2) to examine effect modification. RESULTS: There were no differences in functional outcomes and quality-of-life scores, MCID attainment of functional scores, as well as satisfaction and expectation fulfillment between AP and MB. Among higher obesity patients, AP was associated with a poorer KSKS (p = 0.031) and lower proportion of satisfaction fulfillment (p = 0.041) 2 years postoperatively compared to MB. CONCLUSION: We found no differences in functional and quality-of-life outcomes between fixed-bearing AP and MB tibial components among obese patients who underwent UKA. However, among higher obesity patients (BMI ≥ 35 kg/m2), patients with AP tibial component were associated with lower KSKS score and a lower proportion of attaining satisfaction fulfillment 2 years postoperatively.

Improvements in functional outcome and quality of life are not sustainable for patients ≥ 68 years old 10 years after total knee arthroplasty.

PURPOSE: The aims of this study are to evaluate whether improvements in functional outcome and quality of life are sustainable 10 years after total knee arthroplasty (TKA), and the age cut-off for clinical deterioration in outcomes METHODS: Prospectively collected registry data of 120 consecutive patients who underwent TKA at a tertiary hospital in 2006 was analysed. All patients were assessed at 6 months, 2 years and 10 years using the Knee Society Function Score, Knee Society Knee Score, Oxford Knee Score, Short-Form 36 Physical/Mental Component Scores and postoperative satisfaction. One-way ANOVA was used to compare continuous variables, while Chi-squared test to compare categorical variables. Multivariate logistic regression and receiver operating curve analysis was performed to evaluate the predictive factors associated with deterioration of scores postoperatively. RESULTS: Significant improvements were noted in all functional outcome and quality of life scores at 6 months after TKA. Between 6 months and 2 years, the KSFS and OKS continued to improve but the KSKS, PCS and MCS plateaued. Between 2 and 10 years, there was a deterioration in the KSFS and OKS, whilst KSKS, PCS and MCS were maintained. Increasing age was noted to be a significant risk factor for deterioration of KSFS at 10 years with age ≥ 68 as the cut-off value. 91.7% of patients with KSFS Minimally Clinically Important Difference(MCID) (≥ 7 points) continued to be satisfied after 10 years compared to 100.0% who did not experience KSFS MCID deterioration (p = 0.02). CONCLUSION: Patients ≥ 68 years experience deterioration in functional outcomes and quality of life from 2 to 10 years after TKA. LEVEL OF EVIDENCE: Retrospective study, Level III.

Similar postoperative outcomes after total knee arthroplasty with measured resection and gap balancing techniques using a contemporary knee system: a randomized controlled trial.

PURPOSE: The Attune® Knee System provides new instrumentation to achieve symmetric flexion/extension gaps in total knee arthroplasty (TKA). However, there is limited information on the optimal TKA technique using this system. The aim of this randomised controlled trial was to determine which surgical technique results in better postoperative clinical outcomes after TKA using the contemporary Attune® Knee System: the measured resection or gap balancing technique. METHODS: A prospective randomized controlled trial was conducted with 100 patients undergoing TKA using measured resection (n = 50) or gap balancing (n = 50) technique. The measured femoral sizer was used in the measured resection group, while the balanced femoral sizer was used in the gap balancing group. Functional outcomes and quality of life were assessed preoperatively and at 6 months and 2 years post-surgery, using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), the Physical Component Score (PCS) and Mental Component Score (MCS) of Short-Form 36 (SF-36). Using weight-bearing coronal radiographs, the hip-knee-ankle angle (HKA), coronal femoral component angle (CFA), coronal tibial component angle (CTA) and joint line height were also evaluated for each patient. RESULTS: There were no significant differences in the functional scores or the proportion of patients from each group who were satisfied or had their expectations fulfilled at 6 months or 2 years post-surgery. There was also no significant difference in the number of patients who attained minimum clinically important difference (MCID) postoperatively between the groups. Postoperatively, there was no significant difference in the number of HKA outliers between the groups (p = 0.202). The postoperative CFA (p = 0.265) and CTA (p = 0.479) were similar between the groups. There was also no significant difference in the absolute change (p = 0.447) or proportion of outliers (p = 0.611) for joint line height between the groups. CONCLUSION: Both measured resection and gap balancing techniques resulted in comparable functional and quality of life outcomes up to 2 years post-surgery. Both techniques appear to be equally effective in achieving excellent outcomes with the Attune® Knee System. LEVEL OF EVIDENCE: I.

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.

Preoperative Flexion Contracture Does Not Compromise the Outcomes and Survivorship of Medial Fixed Bearing Unicompartmental Knee Arthroplasty.

BACKGROUND: Despite the expanding indications for unicompartmental knee arthroplasty (UKA), the classic indication that limits flexion contracture to <5° in fixed bearing UKA excludes most patients with arthritic knees and has not been challenged in modern literature. This study compared the clinical outcomes between patients with severe flexion contracture and controls undergoing UKA. METHODS: Eighty seven medial fixed bearing UKAs performed in patients with severe (≥15°) flexion contracture were matched 1:1 with 87 controls without flexion or recurvatum deformity (-5°

Debridement, Antibiotics, and Implant Retention in Periprosthetic Joint Infection: What Predicts Success or Failure?

BACKGROUND: Debridement, antibiotics and implant retention (DAIR) is the treatment of choice for acute postoperative and acute hematogenous periprosthetic joint infection (PJI). There is limited literature on predictive prognostic factors for DAIR. We aim to report the outcomes of DAIR and investigate the predictive prognostic factors. METHODS: We retrospectively reviewed 106 DAIRs. Failure was defined as requiring removal of TKA implants. Predictive factors that may influence success of DAIR treatment such as age, gender, body mass index, ethnicity, American Society of Anesthesiologists score, comorbidities, preoperative erythrocyte sedimentation rate (ESR) and C-reactive protein, symptom duration, time between total knee arthroplasty and DAIR, cultures, rifampicin use, polyethylene liner change, and antibiotic duration were analyzed. RESULTS: The success rate of DAIR was 69.8% (74/106 patients). For successes, mean time from DAIR-to-mortality was longer than failures (61.6 ± 42.7 vs 9.75 ± 9.60 months, P = .0150). Methicillin-susceptible Staphylococcus aureus PJI (odds ratio [OR] 3.64, confidence interval [CI] 1.30-10.2, P = .0140) was a significant predictor for failure of DAIR. Higher preoperative ESR correlated to failure (OR 1.02, CI 1.01-1.04, P = .008). In successes, mean ESR was 75.4 (66.1-84.6), whereas mean ESR in failures was 116 (88.3-143) (P = .011). An ESR > 107.5 predicted failure with a sensitivity of 51.5 and specificity of 85.2. ESR > 107.5 correlated to failure (OR 6.60, CI 2.29-19.0, P < .001). Repeat DAIRs were strongly correlated to failure (OR 5.27, CI 1.99-13.9, P < .01). CONCLUSION: DAIR failure is associated with earlier time to mortality. Repeat DAIRs, elevated ESR > 107.5, and S aureus PJI are associated with treatment failure and 2-stage revision is recommended.

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.

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.

Patients With Parkinson's Disease Have Poorer Function and More Flexion Contractures After Total Knee Arthroplasty.

BACKGROUND: Parkinson's disease (PD) may negatively influence the rehabilitative course after total knee arthroplasty (TKA). However, functional outcomes in this select group remain poorly defined. We compared complication, mortality and revision rates, as well as patient-reported outcomes, and satisfaction between patients with PD and controls after TKA. METHODS: Patients with PD who underwent primary unilateral TKA were identified and matched 1:1 with a control group using propensity scores adjusting for age, sex, body mass index, Charlson Comorbidity Index, baseline range of motion, Knee Society Knee Score, Knee Society Function Score, Oxford Knee Score, and 36-item Short-Form Health Survey Mental and Physical Component Summary. Functional outcomes and patient satisfaction were assessed at 6 months and 2 years. Complications, survivorship, and all-cause mortality were analyzed. RESULTS: In total, 114 patients were included. Majority of PD patients had Hoehn and Yahr stage 1 or 2 disease. Overall complication rate was 26.3% in the PD group and 10.5% in the control group (P = .030). There was no difference in transfusions, length of stay, and discharge to rehabilitation or readmissions. Patients with PD had more flexion contractures, poorer Knee Society Function Score and Oxford Knee Score at 2 years, and poorer 36-item Short-Form Health Survey Physical Component Summary at 6 months. 80.4% of patients with PD were satisfied compared with 85.5% of controls (P = .476). At follow-up of 8.5 ± 2.7 years, one TKA was revised in each group. All-cause mortality was higher in the PD group (15.8% vs 5.3%, P = .067). CONCLUSION: Although patients with PD had relatively poorer knee function and quality of life, these patients still experienced significant functional gains compared with their preoperative status, and high satisfaction was achieved. LEVEL OF EVIDENCE: III.