Lateral Unicompartmental Knee Arthroplasty Utilizing a Modified Surgical Technique and Specifically Adapted Fixed-Bearing Implant.

BACKGROUND: Treatment of isolated lateral compartment arthritic disease with partial knee arthroplasty remains underutilized in comparison to medial unicompartmental arthroplasty. This study examines the survival and outcome of lateral unicompartmental arthroplasty utilizing the first implant specifically developed for the lateral compartment.

MATERIALS AND METHODS: A retrospective review was performed to detect lateral unicompartmental arthroplasty procedures performed in our practice between January 2013 and May 2016. Patients indicated for surgery met specific preoperative clinical and radiographic criteria confirming lateral compartment arthritic disease with a correctable deformity, intact full-thickness medial cartilage, competent anterior cruciate ligament, and minimal disease in the patellofemoral compartment. A single implant design was used in all cases which consisted of a fixed-bearing tibial component specifically adapted to lateral compartment anatomy. Unicompartmental arthroplasty surgical technique was adjusted to attempt to recreate lateral compartment kinematics.

RESULTS: Fifty-two consecutive patients (56 knees) with lateral unicompartmental arthroplasty procedures meeting minimum two-year follow up were included in the study. Thirty-nine patients were female, and 93% of cases were performed for treatment of osteoarthritis. At a mean follow up of nearly three years, Knee Society clinical and functional scores improved postoperatively by a mean difference of 41 and 21, respectively. There were two reoperations, one medial unicompartmental arthroplasty for osteoarthritis progression and a superficial debridement for a non-healing wound. Thus, failure of lateral unicondylar knee arthroplasty (UKA) was less than 2% in this study. There were no other component revisions, radiographic evidence of loosening, or clinical failures.

CONCLUSIONS: At early follow up, lateral unicompartmental arthroplasty using a modified surgical technique and an implant specifically designed for the lateral compartment is a reliable treatment for isolated lateral femorotibial arthritis when meeting defined indications.