Update on treatment of the infected nicompartmental knee arthroplasty

Background: Periprosthetic joint infection (PJI) following unicompartmental knee arthroplasty (UKA) is a rare but serious complication, with an incidence ranging from 0.1% to 1.0%. While the rate of infection is significantly lower than that observed in total knee arthroplasty (TKA), the optimal management strategy remains a subject of clinical debate due to the unique anatomical considerations of the partially resurfaced joint and a paucity of high-level evidence.

Objective: This review aims to evaluate current epidemiological data, diagnostic criteria, and surgical management strategies for infected UKA, specifically comparing the efficacy of debridement, antibiotics, and implant retention (DAIR) against one-stage and two-stage revision procedures.

Key Points: Diagnostic protocols for UKA infection mirror those of TKA, utilizing serum inflammatory markers and synovial fluid analysis; however, synovial white blood cell counts may be higher in UKA. Management options include DAIR for acute presentations and staged revision to TKA for chronic cases. Although DAIR is less invasive, registry data indicate higher failure rates (29%–45%) compared to two-stage exchange. The presence of native cartilage in the non-resurfaced compartments may serve as a nidus for persistent infection, potentially compromising the success of implant retention. Conversely, the preservation of native tissue and smaller metallic volume may enhance local immunological defenses.

Conclusion: While UKA infection is infrequent, its management requires a multidisciplinary approach. DAIR may be appropriate for early infections, but chronic PJI typically necessitates conversion to TKA. Further large-scale registry studies are required to establish standardized treatment algorithms and optimize long-term functional outcomes.