Unicompartmental knee arthroplasty in obese patients, poorer survivorship at 15 years.

Introduction: The preclusion of obese patients from unicompartmental knee arthroplasty (UKA) has increasingly been challenged. This study aimed to evaluate the impact of Body Mass Index (BMI) on UKA at 15-year follow-up. Materials and methods: 169 unilateral UKA patients from 2003 to 2007 were followed-up prospectively for at least 15 years. 70 patients were left for analysis after accounting for patient demise, revision surgery and loss to follow-up. 48 of these patients (69%) were in the Control group (BMI <30 kg/m2) and 22 (31%) were in the Obese group (BMI ≥30 kg/m2). Patients were assessed before and after operation using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), and Physical (PCS) and Mental (MCS) component of the Short Form 12. Survivorship analysis was also performed. Results: Obese patients went through UKA at an earlier age than the non-obese patients (54.7 ± 4.7 years compared to 59.9 ± 7.8 years, p = 0.005). At 2, 10, and 15-year follow-up, both groups achieved clinically significant improvements in outcomes. There was no significant association found between obesity and outcome using multiple linear regression. While propensity matching found PCS improvement at 2 years to be greater in obese patients, no significant association between obesity and 15-year outcome was found. All 13 patients who required revision, underwent total knee arthroplasty (TKA). The overall 15-year survivorship was 74.2% within the obese group and 92.4% within the control group. Conclusion: Compared to non-obese patients, obese patients had poorer 15-year survivorship with greater odds of requiring revision surgery. However, assuming implant survival, obese patients can expect a non-inferior outcome relative to their non-obese counterparts in all patient reported outcome measures 15 years after surgery.

Patient Acceptable Symptom State Thresholds for the Knee Society Score, Oxford Knee Score, and 36-Item Short Form Survey Ten Years Following Unicompartmental Knee Arthroplasty.

BACKGROUND: The patient acceptable symptom state (PASS) refers to a cutoff value on any patient-reported outcome measures (PROMs) scale, beyond which patients consider themselves as having achieved an acceptable outcome. This study aimed to identify PASS thresholds for knee-specific and generic PROMs at 10 years post-unicompartmental knee arthroplasty (UKA). METHODS: There were 269 patients who underwent UKA for medial osteoarthritis from 2004 to 2007 at a single institution and were surveyed preoperatively and 10 years postoperatively using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), 36-Item Short Form Survey (SF-36) Mental Component Score (MCS), and SF-36 Physical Component Score (PCS). Treatment outcomes and expectations were assessed using an anchor question, and PASS attainment was determined using the Youden index on a receiver operating characteristic (ROC) curve. Also, a similar study that identified 2-year long-term PROM PASS thresholds for UKA was referenced and compared. RESULTS: Overall, 91.1% reported acceptable outcomes. The area under the curve for ROCs of KSKS, OKS, and PCS were 0.80, 0.75, and 0.71, respectively. The area under the curve for ROCs of KSFS and MCS were both 0.64. The PASS thresholds were 67.5 for KSFS, 70.5 for KSKS, 39.5 for OKS, 44.6 for PCS, and 43.8 for MCS. Patients who achieved a PASS were at least 3 times more likely to have satisfactory outcomes. CONCLUSIONS: To our knowledge, this is the first study that identified 10-year long-term PROM PASS thresholds for UKA. Accounting for our finding that a decade-long follow-up yielded lower PASS thresholds, time-specific UKA PROM PASS thresholds should be considered. LEVEL OF EVIDENCE: III.

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.

Long-Term Outcomes of Articular Surface Replacement (ASR) Implant in Hip Arthroplasty: A Single Institution Review.

Various metal-on-metal (MoM) total hip replacements (THRs) have been found to have high short-term failure rates due to adverse responses to metal debris (ARMD). As a consequence, several low-performing THRs have been removed off the market. The purpose of this research was to look at the at least five-year outcomes of patients who had MoM hip arthroplasty at our institution. In one specialised centre between 2007 and 2008, 24 Articular Surface Replacement (ASRTM, DePuy, Warsaw, IN, USA) MoM THRs (in 24 patients, mean age: 56.4 years) were implanted. DePuy ASR hip prosthesis for osteoarthritis or hip fractures were employed in the THR system. All patients were summoned back for a clinical assessment, and imaging was done as needed. The average period of follow-up was 8.0 years (6.0-10 years). In all, eight instances (33.3%) were discovered to have pseudotumors, four hips (16.7%) were revised, and one (4.1%) was operated for ARMD. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Oxford ratings improved statistically significantly five years after surgery in all three areas of pain, disability, and stiffness; however, there was no statistically significant change in the 36-Item Short Form Survey (SF-36) (mental) score. MoM hip arthroplasty had a greater revision incidence at five years in our group, presumably owing to the adoption of a smaller femoral head size.

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.

Incomplete Periprosthetic Atypical Femoral Fracture With Concomitant Hip and Knee Arthroplasties: A Case Report.

CASE: We present a case of an incomplete periprosthetic femoral fracture at the mid-distal third of the femoral stem after 11 months of bisphosphonate use. It is 1 of 4 cases of mid-distal periprosthetic atypical femoral fractures (PAFFs) found in our literature review. She was treated with protected weight-bearing, cessation of bisphosphonates, and teriparatide. Eighteen months after diagnosis, follow-up radiographs showed a bridging callus and reduction of a transverse fracture line. CONCLUSION: The incomplete PAFF was contributed by both decreased bone turnover from bisphosphonate use and increased mechanical stress at the lateral femoral cortex. Her previous left bipolar hemiarthroplasty and subsequent Total Knee Arthroplasty shifted the mechanical alignment medially, hence increasing tensile stress.

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.

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.

Preoperative mental distress is associated with poorer physical improvements after revision total hip arthroplasty.

Aims: Despite the increasing prevalence of mental health disorders in revision arthroplasty patients, the impact of preoperative mental distress on functional outcomes after revision total hip arthroplasty (rTHA) remains unclear. Our study aims to investigate the impact of preoperative mental distress on functional outcomes after rTHA. Methods: Prospectively collected data of 84 rTHAs was extracted from a single institution's joint replacement registry. Preoperative Short Form-36 (SF-36) mental component summary (MCS) was used to dichotomize patients to those who were distressed (MCS <50) and non-distressed (MCS ≥50). Multivariable analysis was used to analyze the impact of preoperative mental distress on various outcomes such as the SF-36 physical component summary (PCS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Hip Score (OHS), patient satisfaction and expectation fulfilment at 6 months and 2 years postoperatively. Results: Compared to non-distressed patients, patients with preoperative mental distress had poorer improvements in PCS (+11.4 vs + 16.9, p = 0.007) and lower rates of minimal clinically important difference (MCID) attainment (55.2% vs 73.0%, p = 0.026) at 2 years postoperatively. However, there were no significant differences in improvements for WOMAC and OHS (p > 0.05). Despite experiencing greater absolute improvements in MCS (+12.1 vs -2.1, p < 0.001) and higher MCID attainment rates (65.5% vs 24.3%, p = 0.005) at 2 years, preoperatively distressed patients had lower MCS levels compared to their non-distressed counterparts at all time points (p-value<0.05). There were no significant differences in patient satisfaction (p = 0.509) or expectation fulfilment (p-value = 0.342) at 2 years postoperatively. Conclusion: Revision THA led to substantial mental health improvements in patients with preoperative mental distress. Despite this, preoperative mental distress was associated with poorer physical improvements after surgery.

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.

Bone-on-Bone Contact on Radiograph is not a Prerequisite for Successful Outcome in Fixed-Bearing Medial Unicompartmental Knee Arthroplasty-A 10-Year Follow-Up Study.

INTRODUCTION: Patients without bone-on-bone osteoarthritis are excluded from mobile-bearing unicompartmental knee arthroplasty due to higher revision rates and poorer outcomes. However, we do not know if the same indication applies to fixed-bearing unicompartmental knee arthroplasty implants. Our study aims to compare functional outcomes and revision rates in patients with and without bone-on-bone arthritis undergoing fixed-bearing medial unicompartmental knee arthroplasty. MATERIALS AND METHODS: We reviewed 153 fixed-bearing medial unicompartmental knee arthroplasties in a single institution. Patients were divided into four groups based on joint space remaining measured on preoperative radiographs. Group 1 included knees with bone-on-bone contact; group 2 included knees with less than 2 mm joint space; group 3 included knees with 2 to 4 mm joint space; group 4 included knees with more than 4 mm joint space. Patients were followed up for 10 years postoperatively and assessed using the Oxford Knee Score, the Functional Score and Knee Score from the Knee Society Clinical Rating Score, and the Short Form 36 Health Survey. RESULTS: There was no difference in terms of demographic data and preoperative scores. Postoperative Knee Society Functional Score was found to be lower in group 1 as compared with the other groups. There was no difference between the four groups of patients in terms of Knee Society Knee Score, Oxford Knee Score, and Physical Component Summary and Mental Component Summary Scores from the Short Form 36 Health Survey. There was no difference in terms of survivorship free from all-cause revision at a minimum of 10 years' follow-up. CONCLUSION: Symptomatic patients with varying degrees of arthritis on preoperative radiographs had comparable clinical outcomes. We conclude that symptomatic patients with clinical and radiographic evidence of medial compartment osteoarthritis of any grade can benefit from a fixed-bearing medial unicompartmental knee arthroplasty.

Alignment prior to total knee arthroplasty in high tibial osteotomy patients has no effect on subsequent functional outcomes.

INTRODUCTION: The influence of prior high tibial osteotomy (HTO) on total knee arthroplasty (TKA) functional outcomes remains widely debated. Alignment of failed HTO can pose technical challenges with subsequent TKA. The primary aim of this study was to evaluate the influence of HTO alignment on the clinical outcomes of subsequent TKA. The secondary aim was to compare the time to TKA for each HTO alignment type. METHODS: Patients who underwent TKA post lateral closing-wedge HTO for symptomatic medial compartment osteoarthritis between 2001 and 2014 were prospectively followed up for 2 years. A total of 159 patients were assigned to three groups based on their pre-TKA femora tibia angles using long lower limb radiographs: varus alignment (VrA) ≤ 3o valgus, neutral alignment (NA) 3-9o valgus alignment, valgus alignment (VlA) ≥ 9o valgus. Functional outcomes were quantified using Knee Society Function Score and Knee Scores (KSFS and KSKS respectively), modified Oxford Knee Score (OKS), Short Form 36 Physical Component Score (SF-36 PCS), and SF-36 Mental Component Score (SF-36 MCS). Pre-operative and post-operative knee range of motion were also measured. RESULTS: Mean pre-TKA KSKS in VrA patients (35 ± 18) was significantly lower than both NA (51 ± 19) and VlA (40 ± 21) patients (p < .05). Otherwise, there was no significant difference in functional outcome scores (KSFS, KSKS, OKS, SF-36 PCS and SF-36 MCS) or range of motion at 6 months and 2 years post-TKA. The mean duration from HTO to TKA was 12 ± 7 years with no significant differences between VrA, NA, and VlA HTO to TKA (13 ± 7 years, 13 ± 6 years and12 ± 8 years respectively, p > .05). CONCLUSION: HTO alignment did not influence time to subsequent TKA. HTO alignment did not influence early outcomes as well as radiological outcomes of subsequent TKA. LEVEL OF EVIDENCE: III.

End stage renal disease patients undergoing hip fracture surgery have increased length of stay, acute hospital bill size, and reduced survivorship-implications on a bundled care program.

End stage renal disease (ESRD) is an independent risk factor for the development of hip fractures and is associated with a higher mortality and complication rates. As these patients significantly skew healthcare financing in a bundled care payment (BCP) program, a risk stratified approach to BCPs could be done to take into account the difference in resources required. INTRODUCTION: End stage renal disease (ESRD) is an independent risk factor for the development of hip fractures and is associated with a higher mortality and complication rate. Hip fracture patients with ESRD may significantly skew healthcare financing in a bundled care payment (BCP) program. MATERIALS AND METHODS: ESRD patients undergoing hip fracture surgery from June 2007 to June 2012 within a tertiary hospital in Singapore were identified and matched to two other controls without ESRD based on secondary features of sex, age, fracture type, and surgery performed. Data was collected for American Society of Anesthesiologist (ASA) score, duration of surgery (DOS), length of stay (LOS), 30-day and 1-year mortality, and the presence of 10 other comorbidities: diabetes mellitus (DM), hypertension (HTN), hyperlipidemia (HLD), ischemic heart disease (IHD), arrhythmia (ARR), cerebrovascular disease (CVA), dementia (DEM), asthma (ASTH), peripheral vascular disease (PVD), and anemia (ANE) from electronic medical records. Costs were retrieved from the gross acute hospitalization bill. RESULTS: Forty-one ESRD patients were successfully matched with 82 controls. Patients with ESRD had higher ASA scores (3 vs 2, p = 0.0001), had 75% higher LOS (21 vs 12 days, p < 0.0001), were associated with 67% higher healthcare expenditure (median $20542 vs $12236, p < 0.0001), and 1-year mortality (OR: 19.6, p < 0.0001). ESRD patients had an average of 4.1 comorbidities per patient compared to 1.84 in the control group. CONCLUSION: ESRD is an outsized factor on the outcome of hip fracture patients who have markedly higher and more variable healthcare utilization.

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.

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.

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.

Does obesity lead to lower rates of clinically meaningful improvement or satisfaction after total hip arthroplasty? A propensity score-matched study.

BACKGROUND: Current literature lacks consensus regarding the impact of obesity on clinical outcomes of total hip arthroplasty (THA). The variability of results may reflect the lack of minimal clinically important difference (MCID) analysis, which helps to standardise the interpretation of patient-reported outcome measures (PROMs). We compared the PROMs, patient satisfaction and survivorship between obese and non-obese patients after THA. METHODS: Prospectively collected registry data of 192 obese patients and 192 propensity score-matched controls who underwent primary THA at a single institution were reviewed. Clinical outcomes and satisfaction rates were assessed at 6 months and 2 years. Reoperations for surgical complications and revision rates were analysed. RESULTS: Obese patients had a significantly poorer Oxford Hip Score (OHS) at 6 months and WOMAC-Function at 2 years. However, there was no difference in overall WOMAC, WOMAC-Pain, WOMAC-stiffness, SF-36 mental and physical component summary (PCS). A similar proportion of patients in each group achieved the MCID for OHS, WOMAC and SF-36 PCS. At 2 years, 90.3% of obese patients and 91.7% of controls were satisfied (p = 0.755). At a mean follow-up of 9 years, there were 5 reoperations (2.6%) for surgical complications in the obese group and 1 (0.5%) in the control group; whereas 12 revisions (6.3%) were recorded in the obese group and 3 (1.6%) in the control group (p = 0.021). CONCLUSIONS: Despite a higher revision rate, obese patients undergoing THA may experience a similar level of clinical meaningful improvement and satisfaction as their non-obese counterparts. This study provides valuable prognostic information for obese patients and guides preoperative counselling.

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.

Revision total hip arthroplasty is associated with poorer clinically meaningful improvements and patient satisfaction compared to primary total hip arthroplasty.

PURPOSE: This study aims to compare PROM improvements and satisfaction rates between revision (rTHA) and primary total hip arthroplasty (pTHA). METHODS: 84 rTHAs were propensity-score matched to 168 pTHAs using patient demographics and preoperative PROMs. Multiple regression was used to evaluate differences in PROMs, minimal clinically important difference (MCID) attainment and patient satisfaction. RESULTS: Compared to pTHA patients, rTHA patients had poorer MCID attainment for OHS, WOMAC and SF-36 PCS and lower satisfaction rates at 2-years postoperatively (p < 0.05). CONCLUSION: Patients undergoing rTHA are likely to have poorer outcomes and should be appropriately counselled to better manage their preoperative expectations. LEVEL OF EVIDENCE: Level II.

Cruciate retaining and posterior stabilized total knee arthroplasty in severe varus osteoarthritis knee: A match-pair comparative study in an Asian population.

BackgroundPosterior stabilized (PS) total knee arthroplasty (TKA) is advocated in severe varus osteoarthritic (OA) knees as the posterior cruciate ligament posed challenges in gap balancing. However, there is scarcity in the literature to illustrate the superiority of PS TKA over cruciate retaining (CR) TKA. Our study aims to compare the outcomes between CR and PS TKAs in patients with severe varus OA knees. Methods: A retrospective review was conducted on patients who underwent primary TKA for OA knee from 2003 to 2013. Patients with OA knees of varus tibiofemoral angle ≥15 were matched into two groups (Group CR and PS) according to age, gender, and body mass index and compared in terms of clinical (tibiofemoral alignment, range of motion, and revision rate) and functional outcome (Knee Society Scoring, Oxford Knee Score, Short Form-36 Health Survey). Results: Both Group CR (n = 56) and PS (n = 56) had similar pre-operative scores. Both groups achieved correction of tibiofemoral alignment from median pre-operative varus of 17.6/17.0 (CR/PS) (p = .279) to median post-operative valgus of 4.9/4.0 (CR/PS) (p = .408). Over 24 months, both groups were comparable in achieving significant improvement in clinical and functional outcomes. No case of revision surgery was reported (median follow-up months; CR: 65, PS: 74, p = .549). Conclusion: Both CR and PS TKAs perform similarly well in severe varus OA knee up to 2 years post-operation. Further studies are warranted to assess the long-term outcome between the two implant designs.