Abstract
Introduction
Bicompartmental knee replacement (BKR) may be an alternative to total knee arthroplasty (TKA) for degenerative disease limited to two knee compartments. Most commonly, BKA is a combination of medial compartment and patellofemoral compartment resurfacing. In contrast to TKA, BKA preserves the uninvolved compartment and cruciate ligaments possibly leading to advanced stability and more physiologic knee kinematics. Robotic-assisted systems for unicompartmental knee arthroplasty have shown to provide improved component positioning with dynamic ligament balancing that may improve outcomes of BKA. The purpose of this study was to evaluate the short-term outcomes of patients undergoing BKA at a single institution by a single surgeon using a robotic-assisted system.
Methods
A search of the institution's joint registry was conducted to identify patients that underwent robotic-assisted BKA of the patellofemoral compartment and the medial or lateral compartment between December 2009 and April 2012. All medical records were analyzed for patient demographics and comorbidities. The patients were evaluated preoperatively and at 6,12 months and then annually. The patients were contacted by phone when recent follow-up was not available. The radiographic assessment was also undertaken. The orientation of the tibial and femoral implants was assessed radiologically postoperatively. We examined the clinical results with the Oxford Knee Score (OKS)
Results
A total number of 29 patients (30 BKR) with a mean age of 63.6 years (range 39 to 82) were identified who received a patellofemoral resurfacing in combination with medial (25, 83%) or lateral (5, 17%) compartment resurfacing. The mean BMI was 33.7 kg/m2 (range, 21.5 to 51.8), median Charlson comorbidity index score was 0, median American Society of Anaesthesiologists' (ASA) classification was 3. The mean length of surgery was 40.2 minutes (range, 23 to 151). At a mean follow-up of 15 months (range, 2 to 54), 3 patients (10%, 2 patellofemoral and lateral compartment, 1 patellofemoral and medial compartment) underwent arthroscopic debridement of loose cement fragments following BKA. One patient (3%, patellofemoral and lateral compartment) received manipulation under anesthesia and botulinum neurotoxin injections into the hamstrings for postoperative flexion contracture and another patients (3%, patellofemoral and medial compartment) underwent open lateral retinacular release. There were no component revisions noted during the follow-up period. The preoperative oxford knee score improved from 26.4 to 33.
Discussion
Our analysis shows the bicompartmental knee replacement using robotics is a viable option when two out of three components are involved
