Time-Dependent Features of Complications Following Surface Replacement Arthroplasty for Primary Osteoarthritis of Proximal Interphalangeal Joint.

Background: The extended dorsal central splitting approach (EDCSA) in surface replacement arthroplasty (SRA) for primary osteoarthritis of the proximal interphalangeal (PIP) joint contributes to overcoming problems associated with the volar approach. However, new issues associated with the dorsal approach have become apparent. This study aimed to evaluate the time-dependent features of complications following SRA performed using the EDCSA for primary osteoarthritis of the PIP joint. Methods: This retrospective case series study included 188 patients (140 women and 48 men; 240 fingers) who underwent SRA for primary osteoarthritis of a PIP joint between 2017 and 2024 and were followed up for at least 1 year. Medical records and radiographs were reviewed to identify complications and any revision procedures performed during follow-up. Results: The mean duration of postoperative follow-up was 5.3 years. The mean active arc of motion at the PIP joint improved from 39° preoperatively to 64° at the latest follow-up. Postoperative complications occurred in 62 fingers (26%), and 33 fingers (14%) required revision surgery. Complications involving soft tissues were most common, followed by extension contracture or flexion contracture. The temporal distribution of complications revealed two distinct peaks: early complications within 6 months, which were predominantly flexion contracture, and late complications after 12 months, which were mainly extension contracture with or without swan-neck deformity. No serious new complications were identified beyond 3 years after surgery. Conclusions: SRA for osteoarthritis of a PIP joint continues to be refined, with ongoing efforts to improve outcomes and reduce the risk of complications. The EDCSA provides reliable exposure and allows early rehabilitation, resulting in favourable medium-term outcomes with respect to range of motion, but still has a non-negligible complication rate. Complications show characteristic time-dependent patterns and can be attenuated by timely intervention. Level of Evidence: Level IV (Therapeutic).