Machine learning methods are comparable to logistic regression techniques in predicting severe walking limitation following total knee arthroplasty.

PURPOSE: Machine-learning methods are flexible prediction algorithms with potential advantages over conventional regression. This study aimed to use machine learning methods to predict post-total knee arthroplasty (TKA) walking limitation, and to compare their performance with that of logistic regression. METHODS: From the department's clinical registry, a cohort of 4026 patients who underwent elective, primary TKA between July 2013 and July 2017 was identified. Candidate predictors included demographics and preoperative clinical, psychosocial, and outcome measures. The primary outcome was severe walking limitation at 6 months post-TKA, defined as a maximum walk time ≤ 15 min. Eight common regression (logistic, penalized logistic, and ordinal logistic with natural splines) and ensemble machine learning (random forest, extreme gradient boosting, and SuperLearner) methods were implemented to predict the probability of severe walking limitation. Models were compared on discrimination and calibration metrics. RESULTS: At 6 months post-TKA, 13% of patients had severe walking limitation. Machine learning and logistic regression models performed moderately [mean area under the ROC curves (AUC) 0.73-0.75]. Overall, the ordinal logistic regression model performed best while the SuperLearner performed best among machine learning methods, with negligible differences between them (Brier score difference, < 0.001; 95% CI [- 0.0025, 0.002]). CONCLUSIONS: When predicting post-TKA physical function, several machine learning methods did not outperform logistic regression-in particular, ordinal logistic regression that does not assume linearity in its predictors. LEVEL OF EVIDENCE: Prognostic level II.

Predicting Mobility Limitations in Patients With Total Knee Arthroplasty in the Inpatient Setting.

OBJECTIVE: To develop a prediction model for postoperative day 3 mobility limitations in patients undergoing total knee arthroplasty (TKA). DESIGN: Prospective cohort study. SETTING: Inpatients in a tertiary care hospital. PARTICIPANTS: A sample of patients (N=2300) who underwent primary TKA in 2016-2017. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Candidate predictors included demographic variables and preoperative clinical and psychosocial measures. The outcome of interest was mobility limitations on post-TKA day 3, and this was determined a priori by an ordinal mobility outcome hierarchy based on the type of the gait aids prescribed and the level of physiotherapist assistance provided. To develop the model, we fitted a multivariable proportional odds regression model with bootstrap internal validation. We used a model approximation approach to create a simplified model that approximated predictions from the full model with 95% accuracy. RESULTS: On post-TKA day 3, 11% of patients required both walkers and therapist assistance to ambulate safely. Our prediction model had a concordance index of 0.72 (95% confidence interval, 0.68-0.75) when evaluating these patients. In the simplified model, predictors of greater mobility limitations included older age, greater walking aid support required preoperatively, less preoperative knee flexion range of movement, low-volume surgeon, contralateral knee pain, higher body mass index, non-Chinese race, and greater self-reported walking limitations preoperatively. CONCLUSION: We have developed a prediction model to identify patients who are at risk for mobility limitations in the inpatient setting. When used preoperatively as part of a shared-decision making process, it can potentially influence rehabilitation strategies and facilitate discharge planning.

Pre-existing patellofemoral disease does not affect 10-year survivorship in fixed bearing unicompartmental knee arthroplasty.

PURPOSE: The purpose of this study was to assess 10-year functional outcome and survivorship analysis of patients with significant radiographic evidence of patellofemoral joint arthritis treated with fixed bearing unicompartmental knee arthroplasty. METHODS: Two hundred and sixteen patients (263 knees) that underwent UKA from 2003 to 2005 for a mean of 10.5 ± 2.1 years were prospectively followed up. Preoperative radiological assessment of the patellofemoral joint state was assessed according to the Ahlback classification by an independent assessor and radiographically significant patellofemoral disease was defined as grade 2 or more. Patients with significant bone-on-bone contact in the patellofemoral joint were excluded. RESULTS: Of the 263 knees, 222 (84.4%) had normal patellofemoral joint state and 41 (15.6%) radiologically significant patellofemoral disease. At 10 years' follow-up, the normal and patellofemoral groups had similar OKS (20 ± 7 vs 20 ± 8, n.s.) and KSS scores (79 ± 20 vs 81 ± 20, n.s.), respectively. There were 12 revision surgeries in the normal group and the most common indication for revision was progression of contralateral compartment osteoarthritis (6 of 12 cases). There was only one revision in the patellofemoral group and it was due to progression of contralateral compartment osteoarthritis (n.s.). When all secondary surgeries to the operated knee were considered as failures, the 10-year survival rate was 95.1% (CI 95%: 92.2-97.7%). CONCLUSION: The presence of significant preoperative radiological patellofemoral disease does not affect long-term implant survival and patients have excellent functional outcomes 10 years postoperatively. These patients should not be contraindicated from undergoing unicompartmental knee arthroplasty. LEVEL OF EVIDENCE: III.

Predicting individual knee range of motion, knee pain, and walking limitation outcomes following total knee arthroplasty.

Background and purpose - Up to 20% of patients are dissatisfied after total knee arthroplasty (TKA), mainly because of pain and restricted physical function. We developed a prediction model for 6-month knee range of motion, knee pain, and walking limitations in patients undergoing TKA surgery. Patients and methods - We performed a prospective cohort study of 4,026 patients who underwent elective, primary TKA between July 2013 and July 2017. Candidate predictors included demographic, clinical, psychosocial, and preoperative outcome measures. The outcomes of interest were (i) knee extension and flexion range of motion, (ii) knee pain rated on a 5-point ordinal scale, and (iii) self-reported maximum walk time at 6 months post TKA. For each outcome, we fitted a multivariable proportional odds regression model with bootstrap internal validation. Results - At 6 months post TKA, around 5% to 20% of patients had a flexion contracture ³ 10°, range of motion < 90°, moderate to severe knee pain, or a maximum walk time £â€¯15 minutes. The model c-indices (the probabilities to correctly discriminate between 2 patients with different levels of follow-up TKA outcomes) when evaluating these patients were 0.71, 0.79, 0.65, and 0.76, respectively. Each postoperative outcome was strongly influenced by the same outcome measure obtained preoperatively (all p-values < 0.001). Additional statistically significant predictors were age, sex, race, education level, diabetes mellitus, preoperative use of gait aids, contralateral knee pain, and psychological distress (all p-values < 0.001). Interpretation - We have developed models to predict, for individual patients, their likely post-TKA levels of knee extension and flexion range of motion, knee pain, and walking limitations. After external validation, they can potentially be used preoperatively to identify at-risk patients and to help patients set more realistic expectations about surgical outcomes.

Two year outcomes of minimally invasive hallux valgus surgery.

BACKGROUND: We report our experience with the Minimally Invasive Chevron Akin (MICA) technique for correcting hallux valgus, and evaluate its effectiveness and associated complications. METHODS: Case series of 13 feet with mild to moderate symptomatic hallux valgus treated surgically from July 2013 to December 2014, with at least 48-months follow-up. Patients were assessed pre-operatively and post-operatively with radiographical measurements (Hallux Valgus Angle (HVA) and Intermetatarsal Angle (IMA)) and clinical scores (American Orthopaedic Foot and Ankle Society (AOFAS), 36-Item Short Form Health Survery (SF-36), Visual Analog Scale (VAS)). RESULTS: Mean HVA and IMA decreased from 30.4° and 13.9°-10.9° and 10.2° respectively (p<0.05). The mean AOFAS score improved from an average of 59.0-93.7 (p<0.05). All patients reported a VAS score of 0 post-operatively, and the 4 SF-36 domains improved significantly (p<0.05). CONCLUSIONS: The MICA technique is a safe and effective method in the surgical correction of mild to moderate hallux valgus deformity, and continued use is justified.

Age- and sex-based recovery curves to track functional outcomes in older adults with total knee arthroplasty.

Background: older adults with total knee arthroplasty (TKA) frequently undergo rehabilitation to address limited knee flexion range-of-motion, quadriceps weakness and gait speed limitations. This study aimed to develop age- and sex-specific recovery curves of knee flexion range-of-motion, quadriceps strength and fast gait speed post-TKA. Methods: a population-based sample of 2,987 patients undergoing primary TKA participated, of whom 2015 (68%) were 65 years of age or older. At 4, 8 and 12 weeks post surgery, knee flexion range-of-motion, quadriceps strength and fast gait speed were quantified. Quantile regression was used to determine the percentiles of the knee and gait measures. Results: the various knee and gait measures improved nonlinearly over time, with substantial improvements observed in the 1st 8-10 weeks post surgery. Age-specific, sex-specific recovery curves were developed to show the recovery patterns at multiple percentile levels. A web interface was created to facilitate easy computation of the percentile rank for a given outcome value. Conclusions: we have provided reference percentile values for knee flexion range-of-motion, quadriceps strength and gait speed recovery post-TKA. Such information may assist rehabilitation professionals in interpreting outcomes and quantifying deviations from the expected recovery pattern.

Body mass index changes after unicompartmental knee arthroplasty do not adversely influence patient outcomes.

PURPOSE: The objective of this study is to evaluate the prevalence of patients who lost or gained weight following unicompartmental knee arthroplasty (UKA), the effect of post-operative body mass index (BMI) changes on functional outcomes and quality of life (QoL), and predictive factors associated with BMI changes. METHODS: Prospectively collected data of 1043 patients who underwent UKA between 2000 and 2014 were reviewed. BMI, Knee Society Knee Score and Function Score, Oxford Knee Score (OKS), Short-Form 36 (SF-36) Physical Component Score (PCS) and Mental Component Score and proportion of patients attaining OKS/SF-36 minimal clinically important differences (MCID) were recorded preoperatively and at 2 years post-operatively. The patients were stratified into three groups based on weight changes for further analysis. RESULTS: Following UKA, 138 (13.3%) patients had lost weight, 695 (66.6%) maintained their weight, and 210 (20.1%) gained weight. Patients in all groups demonstrated significant improvements in functional and SF-36 PCS scores at 2 years post-operatively. There were no significant differences in functional outcomes, QoL or revision rate between the groups. Post-operative BMI changes were not correlated with any outcome scores or attainment of MCID (n.s.). CONCLUSIONS: This is the first study that evaluates change in BMI following UKA. It demonstrated a higher proportion of patients who gained weight as compared to those who lost weight. Post-operative BMI changes did not appear to affect outcomes of UKA. These findings will provide important information to surgeons when counselling patients regarding BMI change and its effect on outcomes after UKA. LEVELS OF EVIDENCE: Level III.

The Impact of Diabetes on Patient Outcomes After Total Knee Arthroplasty in an Asian Population.

BACKGROUND: Diabetes is implicated with poorer outcomes and more complications after total knee arthroplasty (TKA). We aim to determine whether diabetes affects infection risk, functional outcomes, patient-reported outcome measures, and patient satisfaction in Asian patients after TKA. METHODS: Prospectively collected data for 905 patients who underwent unilateral TKA by a single surgeon from February 2004 to July 2014 were reviewed, of which 123 (13.6%) patients suffered from diabetes. At 2-year follow-up, the change in range of motion of the operated knee, body mass index, Knee Society Score, Oxford Knee Score (OKS), and Short Form-36 from baseline was compared between diabetic and nondiabetic patients. We also analyzed the length of hospitalization stay, infection risk, and patient satisfaction between the 2 groups. RESULTS: Compared with nondiabetic patients, diabetic patients had significantly poorer preoperative OKS (37.6 on 8.3 to 35.8 .38.0, P = .02) and Short Form-36 Mental Component Score (48.3 Me11.2 to 51.7 1.10.7, P = .01). At 2-year follow-up, diabetes continued to be associated with poorer OKS of 21.2 018.4 and Knee Society Score Function score of 64.7 Fu20.9 compared to 19.1 0.6.2 (P = .02) and 71.8 0220.1 (P = .01) respectively in nondiabetic patients. Interestingly, the difference in mental well-being was no longer significant after TKA. A significantly larger proportion of diabetic patients (50%) had a reduction in body mass index after TKA compared to 36% in nondiabetic patients (P < .01). There was no difference in range of motion, length of hospitalization stay, infection risk, and patient satisfaction. CONCLUSION: Despite poorer physical scores throughout, diabetic patients are no less satisfied and had significantly greater improvement in mental well-being and weight reduction after surgery.

Effect of Mechanical Axis Correction on Outcomes of Hallux Valgus Surgery.

A new method of mechanical axis planning has recently been suggested to aid in corrective surgery for hallux valgus (HV) deformity, which aims to identify the ideal position for the first metatarsal after correction. We investigated the influence of the mechanical axis angle (MAA) correction on the outcomes of corrective HV surgery. We reviewed 50 radiographs to identify the "normal" MAA range within the population. We also reviewed the medical records of 100 patients who had undergone scarf osteotomy at our institution from January 2011 to December 2013. These patients were segregated into 2 groups according to their postoperative MAA: those within the normal range (normal group) and those outside this range (outlier group). We compared the pre- and postoperative functional scores between the 2 groups using statistical analysis. The normal MAA range within our population was 12.5° ± 0.8° (range 11.0° to 14.3°). We found that the physical component summary score of the short-form 36-item health survey was significantly poorer for the outlier group at 6 and 24 months postoperatively compared with the normal group, although the other postoperative scores were comparable. Surgical correction of the MAA to the normal range of the patient population can be recommended because it provides improved quality of life. However, further studies are required to investigate the influence of MAA planning on other standardized foot and ankle scores.

Clinical and radiological outcomes of concomitant endoscopic gastrocnemius release with scarf osteotomy.

BACKGROUND: Studies showed patients with hallux valgus also have tight gastrocnemius concomitantly. This study aims to investigate (1) prevalence of tight gastrocnemius in symptomatic hallux valgus (2) clinical and radiological outcomes of concomitant endoscopic gastrocnemius release with scarf osteotomy. METHODS: Between January 2011 to December 2013, 224 patients underwent hallux valgus surgery were evaluated. They were categorized into 2 groups: scarf osteotomy (n=195), scarf and endoscopic gastrocnemius release (combine, n=29). Clinical outcome measures assessed included VAS, AOFAS Hallux MTP-IP and SF-36 scores. Radiological outcomes included HVA, IMA, HVI and TSP. All patients were prospectively followed up for 6 and 24 months. RESULTS: The prevalence of ipsilateral gastrocnemius tightness in symptomatic hallux valgus is 12.9%. No significant difference in preoperative clinical outcomes between the two groups (all p>.05). Although AOFAS was 6±2 points poorer in the combine group compared to the scarf group at 6 months follow up (p=0.021), at 24 months, all clinical outcomes were comparable between the two groups (all p>0.05). Significant difference in the HVA change between the groups were observed but comparable radiological outcomes in IMA, TSP and HVI at 24 months follow up. CONCLUSIONS: We conclude clinical and radiological outcomes of concomitant endoscopic gastrocnemius release and scarf osteotomy are comparable with scarf osteotomy alone at 24 months.

The minimal clinically important difference for Knee Society Clinical Rating System after total knee arthroplasty for primary osteoarthritis.

PURPOSE: The Knee Society Clinical Rating System (KS) is one of the most popular tools used to assess patient outcome after total knee arthroplasty (TKA), but its minimal clinically important difference (MCID) has not been identified. This study aims to identify the MCID of KS function score (KS-FS) and knee score (KS-KS) after TKA in patients with primary knee osteoarthritis. METHODS: The authors retrospectively analysed patients who underwent TKA for primary knee osteoarthritis between 2005 and 2015 in a single institution. KS-FS, KS-KS, and Oxford Knee Score (OKS) were collected pre-operatively and 2 years post-operatively. Patient satisfaction with TKA at 2 years was also collected. Anchor-based approach with 2 external indicators was used. The MCID for KS-FS and KS-KS was determined using simple linear regression according to patient satisfaction with TKA and the MCID of OKS. RESULTS: The mean age of the 550 subjects studied was 66 ± 8 years. There were 373 (67.8 %) female subjects. The KS-FS improved by 22.8 (95 % CI 20.9-24.6) points, and the KS-KS improved by 44.4 (95 % CI 42.6-46.3) points. The MCID identified for KS-FS is between 6.1 (95 % CI 5.1-7.1) and 6.4 (95 % CI 4.4-8.4) and between 5.3 (95 % CI 4.3-6.3) and 5.9 (95 % CI 3.9-7.8) for KS-KS. CONCLUSIONS: This is the first study, to the knowledge of the authors, to identify the MCID of KS. This will allow future trials to have an accurate prediction of sample size. Clinically, physicians will be able to better interpret outcomes of TKA studies to guide a treatment option. LEVEL OF EVIDENCE: IV.

Outcomes following total knee arthroplasty with CT-based patient-specific instrumentation.

PURPOSE: A 24-month prospective follow-up study was carried out to compare perioperative clinical outcomes, radiographic limb alignment, component positioning, as well as functional outcomes following total knee arthroplasty (TKA) between patient-specific instrumentation (PSI) and conventional instrumentation (CI). METHODS: Ninety consecutive patients, satisfying the inclusion and exclusion criteria, were scheduled to undergo TKA with either PSI or CI. A CT-based PSI was used in this study, and a senior surgeon performed all surgeries. Patients were clinically and functionally assessed preoperatively, 6 and 24 months post-operatively. Perioperative outcomes were also analysed, including operating time, haemoglobin loss, the need for blood transfusion, length of hospitalisation, and radiographic features. RESULTS: At 24-month follow-up, clinical and functional outcomes were comparable between the two groups. PSI performed no better than CI in restoring lower limb mechanical alignment or improving component positioning. There were no differences in operating time, haemoglobin loss, transfusion rate, or length of hospitalisation between PSI and CI. CONCLUSION: No significant clinical benefit could be demonstrated in using PSI over CI after 24 months, and routine use of PSI is not recommended in non-complicated TKA. LEVEL OF EVIDENCE: II.

Effect of Spinal Fusion Surgery on Total Hip Arthroplasty Outcomes: A Matched Comparison Study.

BACKGROUND: Studies regarding postoperative outcomes after primary total hip arthroplasty (THA) in patients who have comorbid factors tend to focus on medical diseases. However, there is a paucity of literature examining the effect of a patient's orthopedic surgical history on outcomes after THA. Significantly, there are currently no studies on the effect of spinal fusion surgery on THA outcomes. METHODS: A review of 82 consecutive patients who had prior spinal fusion surgery who underwent elective THA from January 1, 2006 to December 31, 2015, was conducted. A matching cohort of 82 patients was selected from the remaining THA patients to maintain a 1:1 ratio control group. This cohort of 82 patients was matched for age, gender, body mass index ±5, preoperative Oxford score ±10, total Short Form-36 score ±10, and total Western Ontario and McMaster Universities Arthritis Index (WOMAC) score ±50. Data on the same functional outcomes were prospectively collected at 6-month and 2-year follow-up for comparison. RESULTS: Patients without spinal fusion had better outcome scores than patients with prior spinal fusion, specifically in their 6-month WOMAC scores (253.33-225.07; P = .046), their 2-year Short Form-36 total scores (79.71-69.21; P = .041), and their 2-year WOMAC scores (213.5-267.41; P = .054). CONCLUSION: This study demonstrates that patients with prior spinal fusion had worse outcomes after THA than patients without prior spinal fusion. This has clinical significance in counseling patients with previous spinal fusion undergoing THA.

Unexplained Pain Post Total Knee Arthroplasty With an Oxford Knee Score ≥20 at 6 Months Predicts Good 2-Year Outcome.

BACKGROUND: Total knee arthroplasty (TKA) is an effective procedure for end-stage osteoarthritis of the knee. Some patients experience persistent unexplained pain post-TKA despite normal investigations. The purpose of this study is to identify which of these patients are likely to improve without any surgical intervention. We hypothesize that patients with unexplained persistent pain and a poor 6-month Oxford knee score (OKS) post-TKA can improve at 2 years. METHODS: Prospectively collected data for all primary unilateral TKA performed from June 2004 to January 2012 were analyzed to identify which patients with unexplained pain at 6 months will improve at 2 years. Patients were included if they had persistent pain and an OKS <27 at 6 months; normal radiological and clinical investigations; no infection identified; surgery performed for primary osteoarthritis. Two hundred sixty patients with OKS <27 at 6 months were analyzed. These patients were subdivided into 2 groups (group 1: 6-month OKS 20-26, group 2: 6-month OKS less than 20). RESULTS: One hundred ninety-one out of 208 (92%) patients in group 1 experienced improvement in pain and outcome at 2 years. Most of the group 1 patients attained a minimal clinically important difference in OKS of at least 5 (P < .001) at 2 years. Group 1 patients also reported better Knee Society Functional Score and Short Form Survey 36 mean scores at 2 years. CONCLUSION: In patients with unexplained pain, an OKS of at least 20 at 6 months predicts good functional outcome at 2 years.

Predicting Satisfaction for Unicompartmental Knee Arthroplasty Patients in an Asian Population.

BACKGROUND: Despite renewed interest in unicompartmental knee arthroplasty (UKA), there is a paucity of published literature with regard to patient satisfaction after UKA within Asian populations. The purpose of this study is to identify characteristics and factors which may contribute to patient dissatisfaction after UKA in a multiracial Asian population. METHODS: Seven hundred twenty-four UKAs were performed between January 2007 and April 2013. Preoperative and postoperative variables were prospectively captured, such as standardized knee scores, knee range of motion, and patient satisfaction scores. These variables were then analyzed with a multiple logistic regression model to determine statistically significant factors contributing to patients' satisfaction. RESULTS: Minimum duration of follow-up was 2 years, with an overall patient satisfaction rate of 92.2%. There was improvement in mean knee range of motion and across various standardized knee scores. Preoperative variables associated with patient dissatisfaction included a poorer preoperative Mental Component Summary, better preoperative knee extension, and better preoperative Oxford Knee Scores. Significant postoperative variables included better Oxford Knee Score at 6 months and Mental Component Summary at 2 years. CONCLUSION: Despite the impressive patient satisfaction rate of UKA in this Asian population, these findings suggest that there is a targeted group of patients with select preoperative factors who would benefit from preoperative counseling.

Minimally Invasive Computer-Assisted Total Knee Arthroplasty Compared With Conventional Total Knee Arthroplasty: A Prospective 9-Year Follow-Up.

BACKGROUND: Studies on minimally invasive computer-assisted total knee arthroplasty (MICA-TKA) have shown promising results, but are limited by short follow-up. The purpose of this study was to compare the midterm radiographic features and functional outcomes between patients who underwent MICA-TKA and conventional TKA. METHODS: A total of 108 patients who were randomized to undergo MICA-TKA or conventional TKA during 2004 and 2005 were contacted for a prospective follow-up review. Patients who were lost to contact, have passed away, or declined to participate in the study were excluded. Objective functional measurements and radiographs were obtained for assessment. RESULTS: By the time of this study, 2 patients from the conventional group had undergone revision TKA, one due to infection and one due to aseptic loosening. A total of 67 patients (62.04%) were followed up for an average period of 9.07 years (8.51-9.61 years). At follow-up, functional scores were comparable between the 2 groups. No significant intergroup differences were found in mechanical knee alignment and component placement angle in the coronal views. No statistical or clinical significance were noticed in radiographic signs of component loosening. CONCLUSIONS: MICA-TKA provided similar clinical, functional, and radiographic outcomes compared with conventional TKA after an average of 9-year follow-up. This technique can be used to exploit its short-term advantages without compromising midterm outcomes.

Early Outcomes of Unicompartmental Knee Arthroplasty in Patients With Preoperative Genu Recurvatum of Non-neurological Origin.

BACKGROUND: This study aims to evaluate outcomes of unicompartmental knee arthroplasty (UKA) in patients with preoperative genu recurvatum. METHODS: From patients who underwent UKA at a tertiary hospital between 2005 and 2012, the study selected 30 patients with genu recurvatum (group A) compared with a matching cohort of 60 without genu recurvatum (group B). Group A was also compared with a matched cohort of 60 patients with genu recurvatum who underwent total knee arthroplasty (group C). Functional outcomes data were prospectively collected at 6-month and 2-year follow-up. RESULTS: Two years after UKA, group A had poorer Oxford Knee Score of 22 ± 8 compared with group B at 16 ± 3 (P < .001), and the trend is reflected in the Knee Society Score (71 ± 17 vs 87 ± 17, P < .001) and the 36 Item Short Form Health Survey Physical Component Score (47 ± 10 vs 52 ± 6, P = .014). After 2 years, group C had superior Oxford Knee Score (16 ± 2, P < .001), Knee Society Score (82 ± 14, P = .003), and 36 Item Short Form Health Survey Physical Component Score (53 ± 6, P = .005). The hyperextension angle in group A decreased from 6° ± 2° to 2° ± 4° after 2 years with an improvement of 4° ± 4° (P < .001). The hyperextension angle in group C decreased from 7° ± 2° to 1° ± 3° after 2 years with an improvement of 6° ± 3° (P < .001) with a significant difference (P = .002) in hyperextension angle correction between group A and C. CONCLUSION: Preoperative recurvatum is a predictor of poorer outcome after UKA, and this patient population benefits from better 2-year functional outcomes after total knee arthroplasty.

Cruciate retaining versus posterior stabilized total knee arthroplasty after previous high tibial osteotomy.

PURPOSE: This study aimed to investigate the clinical outcome of total knee arthroplasty (TKA) after previous high tibial osteotomy (HTO) using cruciate retaining (CR) versus posterior stabilized (PS) prostheses. METHODS: Between 2001 and 2010, 133 patients who underwent TKA after previous HTO were included in this study and prospectively followed up for two years. Two independent assessors recorded the range of motion of the operated knee, anterior-posterior (AP) laxity, medial-lateral (ML) laxity, Oxford Knee Score (OKS), Knee Society Function Score (KSFS) and Knee Society Knee Score (KSKS). RESULTS: Thirty-three patients received CR prostheses, while 100 patients received PS prostheses. The median (inter-quartile range) knee flexion at 6 months and 2 years post-TKA was 101° (90, 116) and 110° (90, 118), respectively for the CR group, compared to 115° (100, 121) and 118° (108, 125) for the PS group (p = 0.010 and p = 0.009, respectively). AP and ML laxities were comparable in both groups of patients. While both groups of patients showed improvement in OKS, KSFS and KSKS at 6 months and 2 years post-TKA, there was no significant difference in these clinical scores between the two groups at both time points of follow-up. None of the 133 patients required revision surgery. CONCLUSIONS: Although PS prostheses offer better knee flexion in TKA after previous HTO, the knee stability, clinical scores and revision rate at 6 months and 2 years post-TKA are comparable between CR and PS prostheses. The authors conclude that CR is an alternative to PS prostheses in patients undergoing TKA after previous HTO. LEVEL OF EVIDENCE: III.

Effects of anesthetic technique on blood loss and complications after simultaneous bilateral total knee arthroplasty.

AIMS: Anesthetic technique affects perioperative outcomes, but less was known in simultaneous bilateral total knee arthroplasty (BTKA). A single center, retrospective analysis was carried out to prove the hypothesis that utilization of regional anesthesia would result in favorable perioperative outcomes. METHODS: Medical records of patients admitted for simultaneous BTKA between 2004 and 2013 were analyzed. Two groups, the general anesthesia (GA) and regional anesthesia (RA) group, were identified. Patient preoperative characteristics were compared. Perioperative outcomes measured included blood loss, transfusion requirement, length of hospitalization, operating time, and 30-day perioperative complications. RESULTS: A total of 513 patients were identified, 54.6% were performed under GA, and 45.4% under RA. Patient characteristics were similar between the two groups, except that patients operated under GA were younger than those under RA. RA was associated with significantly less perioperative blood loss (981 vs. 1075 mL, p = 0.017) and 30-day complications (6.4 vs. 13.2%, p = 0.016). Systemic and organ specific infections were particularly lower in the RA group (0.4 vs. 3.9%, p = 0.009). Transfusion requirement, length of hospitalization, and operating time were similar between the two groups. After correcting for covariates, RA offered a 92 mL (p = 0.023) reduction in blood loss and 49% less overall complications (p = 0.047), compared to GA. CONCLUSION: Patients who underwent simultaneous BTKA under RA had lesser blood loss and lower complication rate than GA. The impact of RA can be further exploited to improve perioperative outcomes of simultaneous BTKA in addition to various other interventions.

Are patients more satisfied and have better functional outcome after bilateral total knee arthroplasty as compared to total hip arthroplasty and unilateral total knee arthroplasty surgery? A two-year follow-up study.

This study aims to review the quality of life and physical improvement achieved by total joint arthroplasty surgery, namely unilateral TKA, bilateral TKA and THA. We hypothesize that patients who undergo bilateral TKA should have greater improvement in patient-reported outcome measures, as compared to patients who had unilateral TKA, and their outcomes may be comparable to that of THA. We analyzed prospectively collected data of all patients who underwent unilateral TKA, bilateral TKA and THA (5291, 187 and 529 patients respectively) for end-stage osteoarthritis at a tertiary hospital during the 5-year period. Patients who underwent bilateral TKA had a greater degree of improvement in SF-36 and Knee Society Scores as compared to unilateral TKA at 6 months and 2 years follow-up. Bilateral TKA had the highest proportion of patients who were satisfied and had expectations met by surgery.