Outcomes of Surface Replacement Proximal Interphalangeal Joint Arthroplasty Using the Self Locking Finger Joint Implant: Minimum Two Years Follow-up

Background: The Self Locking Finger Joint (SLFJ) implant is a new type of surface replacement implant. The purpose of this study was to evaluate midterm clinical outcomes of the proximal interphalangeal (PIP) arthroplasty with the SLFJ implant. Methods: We retrospectively studied 26 PIP joint arthroplasties using the SLFJ implant in 17 patients with osteoarthritis or posttraumatic osteoarthritis. Preoperative and postoperative range of motion, grip strength and key pinch, radiographic findings, and complications were evaluated. The Disabilities of the Arm, Shoulder, and Hand (DASH) score, visual analog scale (VAS) score, course of pain, and patient satisfaction were obtained. Results: The mean follow-up time was 44 months (range, 24-76 months). The average active PIP joint arc of motion improved from 36° before surgery to 44° after surgery. Grip strength and key pinch showed no statistical difference between preoperative and postoperative assessments. The average DASH score and VAS score improved from 40 to 15 and from 5 to 1, respectively. Overall patient satisfaction was 94%. Ninety percent of implants showed osteointegration, and there were no radiographic signs of migration and loosening. Three joints (12%) showed abnormal heterotopic bone formation. Four joints (15%) had secondary surgery—1 joint needing joint head and socket replacement and 3 joints needing contracture release. Conclusions: Our minimum 2 years of follow-up evaluation of the SLFJ implant PIP joint arthroplasty demonstrated good pain relief and good overall patient satisfaction while maintaining joint range of motion. The SLFJ implant showed good osteointegration. Further longer-term prospective studies with various types of currently available implants are needed.