Kuang-Ying Yang

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.

Stress fracture of the medial tibial plateau after minimally invasive unicompartmental knee arthroplasty: a report of 2 cases.

Minimally invasive unicompartmental knee arthroplasty has been increasingly popular for the past few years. Several short- and medium-term published reports have shown it to be as efficacious as open unicompartmental knee arthroplasty, with reduced morbidity. However, complications specifically related to the minimally invasive techniques are not well documented. We report 2 cases of stress fracture of the medial tibial plateau after unicompartmental knee arthroplasty with minimally invasive instrumentation. Awareness of this as a possible complication, with increased care in surgical technique, will help to avoid this problem.

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.

A Study on Indirect and Intangible Costs for Patients with Knee Osteoarthritis in Singapore

OBJECTIVES To estimate indirect costs through human capital approach and intangible costs through willingness-to-pay (WTP), and identify factors potentially affecting these costs in multiethnic Asian patients with knee osteoarthritis (OA). METHODS Data were collected through face-to-face interviews among knee OA patients. Human capital approach was used to estimate indirect costs by multiplying: 1) days of absence from work because of OA, with average earnings per capita per day for working patients; or 2) productivity loss with the market price of housekeeping for retirees/homemakers. A closed-ended iterative bidding contingent valuation method was used to elicit willingness-to-pay for a hypothetical cure of OA as a proxy for intangible costs. Mann-Whitney U or Kruskal-Wallis H-tests were performed in univariate analyzes, and linear regression in multivariate analyses. RESULTS Indirect costs per year and intangible costs were estimated at US

Are they relevant? A critical evaluation of the international classification of functioning, disability, and health core sets for osteoarthritis from the perspective of patients with knee osteoarthritis in Singapore

1008 and US

PAR32 INVESTIGATION OF RESPONSE SHIFT IN HEALTH-RELATED QUALITY OF LIFE AMONG PATIENTS UNDERGOINGTOTAL KNEE REPLACEMENT

1200, accounting for 2.8% and 3.3% of annual household income, respectively. The indirect costs were significantly higher for male or working patients, while intangible costs were higher for Chinese, working patients, with higher income, or worse global well-being. CONCLUSION This study demonstrated that eliciting indirect costs through human capital approach and intangible costs through WTP are acceptable and feasible in Asian patients with knee OA. Besides the direct costs, the indirect and intangible costs for the OA patients could be substantial.

PAR11 ARE THEY MEASURABLE? A STUDY ON ELICITING INDIRECT AND INTANGIBLE COSTS OF KNEE OSTEOARTHRITIS USING HUMAN CAPITAL APPROACH AND WILLINGNESS-TO-PAY IN MULTIETHNIC ASIAN POPULATION IN SINGAPORE

Objectives: To determine the extent to which health items identified from the perspective of patients with knee osteoarthritis can be linked with the International Classification of Functioning, Disability and Health (ICF); and to evaluate critically the content validity of ICF comprehensive and brief core sets for osteoarthritis. Methods: Items identified from a focus group study were linked independently by two researchers based on the 10 a priori linking rules. Both percentage agreement and κ statistics were calculated to measure interobserver agreement. Any disagreements were resolved by reaching a consensus among the researchers. The categories linked with all items were compared with the comprehensive core set, while the categories linked with those items reported as important by over 30% of subjects within each of three local ethnic groups (Chinese, Malay, and Indian) were compared with the brief core set. Both comparisons were made only at the second level of the ICF. Results: In all, 74 items were linked with 44 different ICF categories through 105 linkages with generally good interobserver agreement. The 69 items were linked with the ICF at the third or fourth levels. Both commonalities and disparities were found through comparison between the categories linked with these items and both core sets. Conclusions: All items could be successfully linked with the ICF. The comprehensive core set showed good content validity, while the brief core set needs to be supported by more empirical evidence in various sociocultural contexts. This study specifically complemented the development and refinement of both core sets from the perspective of patients with knee osteoarthritis.

Total Knee Arthroplasty in Diabetic Patients A Study of 109 Consecutive Cases

PAR32 INVESTIGATION OF RESPONSE SHIFT IN HEALTH-RELATED QUALITY OF LIFE AMONG PATIENTS UNDERGOINGTOTAL KNEE REPLACEMENT Zhang XH, Li SC, Xie F, Lo NN,Yang KY,Yeo SJ,Thumboo J National University of Singapore, Singapore, Singapore, University of Newcastle, Callaghan, NSW, Australia, Singapore General Hospital, Singapore, Singapore OBJECTIVES: To investigate the presence and impact of response shift (RS) in HRQoL among patients undergoing total knee replacement (TKR) and explore factors associated with RS. METHODS: HRQoL of TKR patients was assessed by SF-6D at 0-month (just before surgery: pre-test1), 6 months (pre-test2) and 18 months after surgery (post-test). At 18-month, HRQoL at 0-month and 6-month was evaluated again by “then-test” approach. RS was calculated as the score difference between corresponding preand then-test. Descriptive analysis was used for demographics, medical information and satisfaction with knee surgery (on a 0–10 Likert scale). Wilcoxon Signed Rank tests were used for comparisons of RS at 0-month and 6-month. Relationships between RS and external variables were investigated by Mann-Whitney, Kruskal-Wallis tests or Spearman’s correlation. Multiple liner regression (MLR) models were used to explore factors potentially impacting RS. Unless specified, median (interquartile range) was reported and significance level was set at 0.01. RESULTS: Data were analyzed from 74 subjects [mean (SD) age 68.9 (7.9) years, 81% female, 92% with less than 12 years of education, 72% with acute and 68% with chronic illness, 10% with past knee surgery history, mean (SD) surgery satisfaction of 8.0 (1.3)]. SF-6D scores for then-tests at 0-month [0.48 (0.42, 0.49)] and 6-month [0.72 (0.66, 0.79)] were significantly different from respective pre-test scores [0.61 (0.58, 0.68) at 0-month, 0.69 (0.63, 0.72) at 6-month], both indicating presence of RS. RS at 0-month was significantly larger than that at 6-month. RS at 0-month was not affected by demographic or medical variables. RS at 6-month was greater in subjects with higher education (p < 0.01, 16% of variance in MLR). CONCLUSION: RS was present and impacted HRQoL assessment among patients undergoing TKR both just prior to and 6 months after surgery. RS investigation is thus suggested to be performed during HRQoL evaluations.

Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) in Asians with knee osteoarthritis in Singapore

PAR9 CO-PRESCRIPTION OF GASTROPROTECTIVE AGENTS FOR PATIENTS AT RISK OF NSNSAID-INDUCED GASTROINTESTINAL HARM Lister S, Makinson G, Koncz T Pfizer Ltd,Tadworth, UK, Pfizer Limited,Tadworth, UK OBJECTIVE: Patients prescribed non-selective (ns) NSAIDs are at risk of gastrointestinal (GI) adverse events, hence the coprescription of gastroprotective agents (GPAs) as prophylactic therapeutic options. Concerns over appropriate GPA coprescribing, especially for high-risk patients, prompted this assessment of the level of GPA co-prescription for patients at GI risk. METHODS: A primary care database (DIN-LINK), representative of the UK, containing records of over 800,000 patients was used. Patients with osteoarthritis and/or rheumatoid arthritis who received nsNSAIDs and co-prescribed GPA between September 2003 and August 2005 were identified. Gastroprotection level (%) was defined by days on GPA within any three months of nsNSAID use. Patients were grouped by level of gastroprotection. For each month, the percentage of patients at different levels of gastroprotection was calculated and analysed according to GI risk factors (NSAID use frequency, serious co-morbidity, aspirin use, and previous GI adverse events). RESULTS: Approximately 25,000 patients with nsNSAID prescriptions were identified. Of these, over half were frequent nsNSAID users (prescribed nsNSAIDs for at least 75% of the observed period), 2.5% had previous GI adverse events, 12% were taking aspirin, and over two thirds had serious co-morbidity. Of total nsNSAID users, 18% used GPAs for the full period (100%); of frequent nsNSAID users, 19.5%. By analysing patients with risk factors and frequent nsNSAID use, the percentage of those using GPAs for the full period was less than 40% with previous GI adverse events, 30% for aspirin takers, and 22% with serious comorbidities. High, but not full (80–99%), GPA use was achieved in similarly low numbers of patients with risk factors. CONCLUSION: Prescription data revealed frequent NSAID users receive little co-prescribed GPAs. Presence of risk factors of NSAID-induced GI risk did not increase GPA use, which may increase GI-related hospitalisation risk.