There has been a recent interest in custom-made partial knee arthroplasties to provide patient-specific instrumentation and better fit of the prosthesis. While unicondylar knee arthroplasties (UKAs) have demonstrated good outcomes and durable results in many studies, there is little evidence on outcomes of these custom-made implants.
We performed a retrospective review of all custom-made UKAs performed at our institution by one surgeon from 2008 to 2015. We analyzed preoperative demographics, clinical follow-up evaluations, and radiographs and performed an analysis of risk factors including age, gender, height, weight, body mass index, and tibial insert thickness. The incidence of revision surgery, radiographic failures indicating component loosening, and symptomatic clinically failed implants was calculated at an average of 54.0 months of follow-up.
We analyzed 115 consecutive custom-made medial UKAs from a single surgeon at our institution and found 29 (25.2%) UKAs had failed at an average of 33.1 months after surgery. Reasons for failure included aseptic femoral loosening (10), aseptic tibial loosening (8), loosening of both components (4), infection (3), progression of osteoarthritis (2), pain (1), and dislodged polyethylene insert (1). We found a significant relationship between implant failure and body mass index; no other study variables were statistically significant.
We found a relatively high rate of aseptic loosening and particularly femoral component loosening in the short- to intermediate-term follow-up period. While further study of larger numbers of custom-made UKA from multiple institutions may help verify these findings, we recommend careful consideration of the use of this implant.