Predictors of Midterm Outcomes after Medial Unicompartmental Knee Arthroplasty in Asians

BACKGROUND: This study was designed to evaluate predictors of good outcomes following medial unicompartmental knee arthroplasty (UKA) in Asian patients. METHODS: Registry data of patients who underwent primary unilateral medial UKA from 2006 to 2011 were collected. Outcomes studied were the Oxford Knee Score (OKS) and the Physical Component Score (PCS) of the Short Form 36 (SF-36) questionnaire. These outcome scores were collected prospectively, pre- and postoperatively up to 5 years. Good outcome was defined as an overall improvement in score greater than or equal to the minimal clinically important difference (MCID). The MCID for the OKS was 5 while the MCID for the PCS was 10. Regression analysis was used to identify predictors of good outcomes following medial UKA. RESULTS: Primary medial UKA was performed in 1,075 patients. Higher (poorer) preoperative OKS (odds ratio [OR], 1.27; p < 0.001), lower (poorer) preoperative PCS (OR, 1.08; p < 0.001), lower (poorer) preoperative Knee Society Knee Score (KSKS; OR, 1.02; p < 0.001) and higher (better) preoperative SF-36 Mental Component Score (MCS; OR, 1.02; p < 0.001) were significant predictors of good outcomes. CONCLUSIONS: Patients with poorer OKS, PCS and KSKS and better SF-36 MCS preoperatively tended to achieve good outcomes by the MCID criterion at 5 years following the index surgery.

Early experiences with robot-assisted total knee arthroplasty using the DigiMatch™ ROBODOC® surgical system

<p><b>INTRODUCTION</b>The use of robotics in total knee arthroplasty (TKA) has been shown to minimise human error, as well as improve the accuracy and precision of component implantation and mechanical axis alignment. The present study aimed to demonstrate that robot-assisted TKA using ROBODOC® is safe and capable of producing a consistent and accurate postoperative mechanical axis.</p><p><b>METHODS</b>We prospectively recruited 27 consecutive patients who underwent robot-assisted TKA between May and December 2012. Two patients were excluded from the study due to intraoperative technical problems with the robot. Long-leg radiography and computed tomography were performed prior to surgery, and used for mechanical axis measurements and component sizing. DigiMatch™ ROBODOC® Surgical System software version 4.3.6 (Curexo Technology Corp, Fremont, CA, USA) was used in all cases to perform bone cuts in accordance with the preoperative plan.</p><p><b>RESULTS</b>The postoperative coronal mechanical alignment was within 3 degrees, with a mean alignment of -0.4 ± 1.7 degrees, confirming the accuracy of the preoperative surgical plan and bone cuts. The mean operating time was 96 ± 15 min, and preoperative planning yielded 100% implant sizing accuracy.</p><p><b>CONCLUSION</b>Robotics has the potential to enable surgeons to consistently attain ideal postoperative alignment. The use of bone movement monitors and an integrated navigation system enhances the safety profile of ROBODOC® by minimising errors. However, the role of the surgeon in TKA is still vital, as the surgeon is ultimately in charge of planning the surgery, its execution and ensuring soft tissue balance during TKA.</p>