The study compared clinical and patient-reported outcomes after proximal interphalangeal (PIP) joint surface replacement in patients with post-traumatic osteoarthritis (OA) and primary OA.

Data from a prospective registry of patients who underwent surface replacing PIP joint arthroplasty (CapFlex-PIP, KLS Martin, Germany) were analysed. The primary outcome was active range of motion (ROM) measured before surgery and at several times up to five years after surgery. Grip strength, the brief Michigan Hand Outcomes Questionnaire (MHQ) and pain during daily activities were also assessed. Using propensity score matching, 22 patients with post-traumatic OA were matched to 110 patients with primary OA based on their preoperative (baseline) ROM. Between-group differences were analysed using the Mann-Whitney U test or Fisher’s exact test.

After matching, the mean baseline ROM of 34° (95% confidence interval [CI]: 22 to 46) for post-traumatic OA patients and 38° (CI: 34 to 42) for primary OA patients were comparable. By one year, ROM improved significantly after PIP arthroplasty to 53° (CI: 45 to 61) and 59° (CI: 55 to 63) for post-traumatic and primary OA patients respectively, and there was no significant difference between groups (p = 0.103). Thereafter, ROM declined in a similar manner for both groups over the 5-year follow-up period. The brief MHQ score and grip strength at baseline and the 1-year follow-up were significantly higher in the post-traumatic OA group. Complications occurred in five post-traumatic OA patients (23%) and in 15 patients (14%) with primary OA (p = 0.327).

Proximal interphalangeal joint surface replacement arthroplasty for post-traumatic osteoarthritis significantly improved range of motion, and this trend was similar to that achieved for patients with primary osteoarthritis. As clinical and patient-reported outcomes also improved, we recommend this procedure for patients with post-traumatic osteoarthritis, but the potentially higher risk of complications and reoperations for post-traumatic osteoarthritis patients should be considered.