The impact of patellofemoral arthritis on unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty (UKA) is an efficient surgical treatment for osteoarthritis or avascular osteonecrosis by resurfacing the medial or lateral compartment of the tibiofemoral joint. If compared to total knee arthroplasty (TKA), UKA can reach the same long-term curative effect, but superiority in less invasive soft tissue dissection, preservation of bone stock, minimal blood loss, faster post-operative rehabilitation and less complications. For the last 15 years, the Oxford Knee phase 3 has been implanted through a minimally invasive approach, and multicenter studies using this approach have reported high survival rates at long-term follow-up. Up to now, UKA has accounted for a significant portion of the patients who need knee replacement. However, there remain some controversies on UKA indications, such as the debate regarding associated patellofemoral arthritis as a contraindication for UKA. As clear indications for UKA are usually rare, surgeon's experience seems to be the key factor for a successful selection of patients. Better understanding of indications may add to improved outcome of UKA. This narrative review aims to summarize the current pros and cons to eliminate patellofemoral arthritis (PFA) as a contraindication for UKA.