Efficacy of Simultaneous Distal Interphalangeal Arthrodesis and Proximal Interphalangeal Surface Implant Arthroplasty for Finger Osteoarthritis: A Comparative Study

<b>Background:</b> Osteoarthritis (OA) of the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints frequently occurs in the same digit. Although PIP implant arthroplasty and DIP arthrodesis are well-established procedures, evidence on their combined application is limited. This study aimed to assess whether performing simultaneous DIP arthrodesis and PIP implant arthroplasty influences the outcomes of PIP implant arthroplasty, compared with performing PIP implant arthroplasty alone. <b>Methods:</b> We retrospectively analysed 18 fingers in 15 patients who underwent simultaneous DIP arthrodesis and PIP surface implant arthroplasty (PIP + DIP group) and compared them with 106 fingers treated with PIP implant arthroplasty alone (PIP-only group). DIP arthrodesis was performed using a dorsal approach with cannulated headless screws or Kirschner wire fixation. PIP arthroplasty was performed using an extensor tendon split approach with the Self-Locking Finger Joint System (Nakashima Healthforce Co., Ltd., Okayama, Japan). Outcome measures included the visual analogue scale (VAS) score for pain; active range of motion (ROM) of the metacarpophalangeal (MP), PIP and DIP joints, and radiographic evaluation of DIP joint union. <b>Results:</b> All fingers in the PIP + DIP group achieved bony union at the DIP joint. Both groups showed significant postoperative improvements in VAS scores and ROM of the MP and PIP joints. A significant reduction in DIP joint ROM was observed. After adjustment for preoperative variables, no significant differences were observed between groups in postoperative VAS scores (2.2 and 0.9 in the PIP + DIP and PIP-only groups, respectively) or PIP joint ROM (67° and 65.3° in the PIP + DIP and PIP-only groups, respectively). <b>Conclusions:</b> Simultaneous DIP arthrodesis and PIP surface implant arthroplasty provided effective pain relief and short-term PIP joint mobility comparable to PIP arthroplasty alone. This combined approach may be a viable surgical option for patients with coexisting DIP and PIP joint OA. <b>Level of Evidence:</b> Level IV (Therapeutic).