Hwei-Chi Chong

Computer-assisted Minimally Invasive Total Knee Arthroplasty Compared with Standard Total Knee Arthroplasty: A Prospective, Randomized Study

BACKGROUND There is little information on the feasibility of computer navigation when using a minimally invasive approach for total knee arthroplasty, during which the anatomic landmarks for registration may be obscured. The purpose of the present study was to determine the radiographic accuracy of this technique and to compare the rate of functional recovery between patients who underwent computer-assisted minimally invasive arthroplasty and those who underwent conventional total knee arthroplasty. METHODS One hundred and eight consecutive patients were randomized to undergo computer-assisted minimally invasive total knee arthroplasty or conventional total knee arthroplasty. Perioperative pain management was standardized. The clinical parameters, long-leg radiographs, and functional assessment scores were evaluated for six months postoperatively. RESULTS Patients who underwent computer-assisted minimally invasive total knee arthroplasty had a significantly longer operative time (by a mean of twenty-four minutes) and a significantly shorter inpatient stay (3.3 compared with 4.5 days) in comparison with those who underwent conventional arthroplasty (p </= 0.001). Significantly more patients in the computer-assisted minimally invasive total knee arthroplasty group were able to walk independently for more than thirty minutes at one month (p = 0.04). The percentage of patients with a coronal tibiofemoral angle within +/-3 degrees of the ideal was 92% for the computer-assisted minimally invasive total knee arthroplasty group, compared with 68% for the conventional total knee arthroplasty group (p = 0.003). CONCLUSIONS Although specific clinical parameters reflect an early increased rate of functional recovery in association with computer-assisted minimally invasive total knee arthroplasty within the first postoperative month, the main advantage of this technique over conventional total knee arthroplasty is improved postoperative radiographic alignment without increased short-term complications.

Peri-articular steroid injection improves the outcome after unicondylar knee replacement: A PROSPECTIVE, RANDOMISED CONTROLLED TRIAL WITH A TWO-YEAR FOLLOW-UP

We have performed a prospective double-blind, randomised controlled trial over two years to evaluate the efficacy and safety of an intra-operative peri-articular injection of triamcinolone acetonide in patients undergoing medial unicondylar knee replacement. We randomised 90 patients into two equal groups. The study group received an injection of triamcinolone acetonide, bupivacaine, and epinephrine into the peri-articular tissues at the end of the operation. The control group received the same injection mixture but without the addition of triamcinolone. The peri-operative analgesic regimen was standardised. The study group reported a significant reduction in pain (p = 0.014 at 12 hours, p = 0.031 at 18 hours and p = 0.031 at 24 hours) and had a better range of movement (p = 0.023 at three months). There was no significant difference in the rate of infection and no incidence of tendon rupture in either group. The addition of corticosteroid to the peri-articular injection after unicondylar knee replacement had both immediate and short-term benefits in terms of relief from pain, and rehabilitation with no increased risk of infection.

Sex Differences and Impact of Body Mass Index on the Time Course of Knee Range of Motion, Knee Strength, and Gait Speed After Total Knee Arthroplasty

Quadriceps strength deficits and gait speed limitations remain significant issues after total knee arthroplasty (TKA), yet detailed longitudinal data characterizing these measures and their predictors are limited. This study aimed to describe the time course of knee range of motion, quadriceps strength, and gait speed post‐TKA, and to assess whether sex and body mass index (BMI) influenced the time recovery of these measures.

Predicting discharge outcomes after total knee replacement using the Risk Assessment and Predictor Tool

OBJECTIVE To explore the use of the Risk Assessment and Predictor Tool (RAPT) as a pre-operative tool to predict postoperative discharge destination and length of stay for patients undergoing total knee replacement (TKR) in Singapore. PARTICIPANTS AND SETTING A cohort of 569 patients undergoing primary TKR at the Singapore General Hospital were recruited prospectively from November 2009 to June 2010. INTERVENTION All patients completed a modified RAPT questionnaire pre-operatively, and underwent standard clinical pathway guidelines for TKR throughout the study. MAIN OUTCOME MEASURES Actual discharge destination (ADDest) and length of stay (LOS). DESIGN Total RAPT score and preferred discharge destination (PDD) were recorded pre-operatively, while ADDest and LOS were obtained immediately after discharge. Multivariable logistic regression and multivariable regression analysis were used to determine whether the RAPT items and score could predict the discharge outcomes. RESULTS Total RAPT score was a significant predictor of LOS for patients following TKR (R=0.24, P<0.001); the higher the RAPT score, the longer the LOS. Total RAPT score was also a significant predictor of actual discharge to home [odds ratio (OR) 2.32, 95% confidence interval (CI) 1.11 to 4.85]. PDD was a significant predictor for LOS (R=0.22, P<0.001) and ADDest (R=0.33, P<0.001). Patients who chose to be discharged home were more likely to be directly discharged home (OR 9.79, 95% CI 5.07 to 18.89, P<0.001). CONCLUSION Total RAPT score and PDD were significant predictors of ADDest and LOS for patients following TKR in Singapore. The ability to predict discharge outcomes following TKR could assist caregivers, healthcare professionals and administrators in optimising care and resource allocations for patients.

Sunday Physiotherapy Reduces Inpatient Stay in Knee Arthroplasty: A Retrospective Cohort Study

OBJECTIVE To evaluate, in patients treated with knee arthroplasty, whether providing Sunday (7d/wk) physiotherapy intervention could decrease length of stay (LOS) without affecting discharge knee functional outcomes. DESIGN Retrospective cohort study. SETTING A tertiary hospital. PARTICIPANTS Patients (N=229) who underwent total or unicompartmental knee arthroplasty. INTERVENTIONS In October 2009, we implemented a Sunday physiotherapy intervention program for patients undergoing knee arthroplasty on Friday or Saturday. Prior to this initiative, physiotherapy intervention was provided from Monday to Saturday. LOS and discharge knee outcomes were compared between patients seen during the 4-month intervention period (n=73) and patients seen in the 4 months prior to the intervention (n=82). To control for secular trends, LOS during the intervention period was compared with LOS during the same 4 months in the prior year (n=74). MAIN OUTCOME MEASURES LOS and discharge knee functional outcomes comprising (1) passive knee flexion range of motion, (2) the proportion of patients who were able to perform an unassisted straight-leg raise, and (3) the proportion of patients who ambulated safely with the use of a single walking stick or quadstick. RESULTS During the Sunday physiotherapy intervention period, median LOS significantly reduced (5-4d). Controlling for secular trends in LOS revealed similar results. The number needed to treat for 1 additional patient to achieve a LOS 4 days or shorter with Sunday physiotherapy intervention was between 3 and 4. There were no significant changes in knee functional outcomes. CONCLUSIONS Sunday physiotherapy intervention was associated with a modest reduction in LOS and a faster short-term knee recovery.

Simultaneous versus staged bilateral unicompartmental knee replacement

We prospectively followed 171 patients who underwent bilateral unicompartmental knee replacement (UKR) over a period of two years. Of these, 124 (72.5%) underwent a simultaneous bilateral procedure and 47 (27.5%) underwent a staged procedure. The mean cumulative operating time and length of hospital stay were both shorter in the simultaneous group, by 22.5 minutes (p < 0.001) and three days (p < 0.001), respectively. The mean reduction in haemoglobin level post-operatively was greater by 0.15 g/dl in the simultaneous group (p = 0.023), but this did not translate into a significant increase in the number of patients requiring blood transfusion (p = 1.000). The mean hospital cost was lower by

Association of surgeon factors with outcome scores after total knee arthroplasty

8892 in the simultaneous group (p < 0.001). There was no significant difference in the rate of complications between the groups, and at two-year follow-up there was no difference in the outcomes between the two groups. We conclude that simultaneous bilateral UKR can be recommended as an appropriate treatment for patients with bilateral medial compartment osteoarthritis of the knee.

Development of a Prediction Model to Estimate the Risk of Walking Limitations in Patients with Total Knee Arthroplasty

Purpose. To identify preoperative factors (including surgeon factors) associated with outcome scores after total knee arthroplasty (TKA). Methods. Medical records of 2848 patients (3458 knees) who underwent primary TKA by 27 orthopaedic specialists were retrieved. Three specialty knee surgeons who had one-year fellowship in TKA performed 1930 TKAs, and 24 general orthopaedic surgeons performed 1528 TKAs. Four of them (including all 3 specialty knee surgeons) were ultra-high-volume (⩾100 TKAs a year), and 21 of them were senior consultants (⩾5 years post residency). At 2 years, 2922 (85%) of knees had complete follow-up data. Oxford Knee Score, Knee Society knee and function scores, and SF-36 quality-of-life score were assessed by independent physiotherapists before and after surgery. Outcomes were compared in terms of dichotomised specialty, seniority, and surgical volume of surgeons. Results. Comparing ultra-high-volume (⩾100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former achieved better outcomes in terms of the Oxford Knee Score at 6 months, Knee Society knee and function scores at 2 years, and SF-36 scores at 6 months and 2 years. Comparing lower-volume (±100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former still achieved better outcome and quality-of-life scores, except for SF-36 Mental Component Score at 2 years. Conclusion. Specialty training and clinical research in TKA improved outcome and quality-of-life scores.

Associations of Self-Report Physical Function With Knee Strength and Knee Range-Of-Motion in Total Knee Arthroplasty Possible Nonlinear and Threshold Effects

Objective. Early and accurate risk prediction of walking limitations after total knee arthroplasty (TKA) is important for clinical and economic reasons. However, to our knowledge, no studies have systematically integrated multiple predictors into a single, clinically practical model. Our study aimed to develop a prediction model to estimate the risk of post-TKA walking limitations. Methods. We performed a prospective cohort study of 1096 patients who underwent elective, primary TKA between July 2013 and September 2014. Candidate predictors included patient demographics, surgical factors, and pre- and early (1-mo) post-TKA functional measures. The outcome of interest was self-reported walking limitations at 6 months of post-TKA. We used multivariable proportional odds regression with bootstrap internal validation to develop the model. Results. In all, 12% of patients reported walking limitations (maximum walk time ≤ 15 min) at 6 months postsurgery. The main predictors of increasing levels of walking limitations were preoperative walking limitations (overall p < 0.001), higher levels of body mass index [interquartile range (IQR)-OR 1.3, 95% CI 1.2–1.5], lower values of 1-month post-TKA gait speed (IQR-OR 1.9, 95% CI 1.3–2.6), the presence of contralateral knee pain (OR 1.9, 95% CI 1.2–3.0), and the use of a quadstick preoperatively (OR 3.5, 95% CI 1.7–7.3). The prediction model had an optimism-corrected concordance index of 0.71. Conclusion. A small but sizable proportion of patients with TKA had persistent mobility limitations. Our prediction model may help to risk-stratify patients, and external validation is required before the model can be used in clinical practice.

Knee extension range of motion and self-report physical function in total knee arthroplasty: mediating effects of knee extensor strength

This study aims to examine, in patients before and following a total knee arthroplasty (TKA), whether knee extensor strength and knee flexion/extension range-of-motion (ROM) were nonlinearly associated with physical function. Data from 501 patients with TKA were analyzed. Knee extensor strength was assessed preoperatively and 6 months postoperatively. Knee ROM and Short Form-36 (SF-36) physical function data were collected from each patient preoperatively, and at 6 and 24 months postoperatively. Knee strength was measured by handheld dynamometry and knee ROM by goniometry. Restricted cubic spline regression was used to examine possible nonlinear associations. At all assessment points, the associations between knee measures and function were not always linear. Some of the associations revealed distinct threshold points. These findings have potential clinical and research implications.