Abstract
Introduction
Bi-compartmental knee arthroplasty (BKA) is an alternative to total knee arthroplasty (TKA) for degenerative joint disease when present in only two compartments. BKA spares the cruciate ligaments and preserves bone in the healthy compartment, possibly leading to better knee kinematics and clinical outcomes when compared to TKA. While BKA is a technically demanding procedure when performed with manual instrumentation, robotic assistance allows for accurate implant placement and soft tissue balancing of the joint. Robotic unicompartmental knee arthroplasty (UKA) has shown favourable clinical outcomes and survivorship at short term (2 year) follow up compared to manual UKA. The purpose of this study is to evaluate the short term functional outcomes and survivorship of patients undergoing robotically assisted BKA.
Methods
45 patients (48 knees) were identified in an initial and consecutive single surgeon series receiving robotically assisted BKA to correct disease in the medial and patellofemoral compartments. As part of an IRB approved study, every patient in the series was contacted at a minimum two year (±2 months) follow up and asked a series of questions to determine implant survivorship and functional outcomes (using the patient portion of the Knee Society Score). 9 patients were lost to follow up and 1 patient was deceased. 35 patients (38 knees) at a minimum two year follow up enrolled in the study for an enrolment rate of 79%. There are 22 male patients and 13 female patients; the average age at time of surgery is 67.0 ± 6.8 and the average BMI is 29.5 ± 4.6. Five patients in this series also qualified for a 5 year follow up assessment.
Results
Only 1 BKA was reported as revised to a TKA at two year follow up. The revision was reported by the patient due to severe pain and occurred 25 months after the index BKA procedure. The patient did not return to the same surgeon for the revision procedure. The average pre-operative Knee Society Function Score was 58.1 ± 9.9 (n=18) and improved at 2 years post-operatively to 81.5 ± 15.9 (n = 36) (p<0.001). Of the 5 patients contacted at a minimum 5 year follow up, there were no reported revisions.
Conclusions
Robotically assisted BKA shows good survivorship and functional outcomes at a short term 2 year follow up. This procedure may be a viable option to patients with only two diseased compartments, as sparing of healthy bone and cruciates may improve overall kinematics and outcomes of the joint. This study remains ongoing to include a larger cohort and longer follow up.
