Introduction: The Self-Locking Finger Joint (SLFJ) prosthesis is a cementless surface implant that can be used to treat inflammatory or degenerative osteoarthritis of the proximal interphalangeal (PIP) joint. The aim of this study was to report the mid-term outcomes and to validate a radiological parameter for bone resorption and loosening. Methods: Sixteen patients (17 prostheses) who were treated with a SLFJ implant were retrospectively included, with a mean follow-up of 7 years (range 2–14). Outcomes included pain, range of motion of the PIP joint and complications. Implant subsidence and osteointegration were assessed on postoperative radiographs. A radiological bone resorption index, ranging from grade 0 to grade 3, was developed. It was scored in 20 zones per prosthesis, and the reliability was tested. Results: The mean visual analogue scale score for pain decreased from 5.3 preoperatively to 1.7 postoperatively, and mean active PIP joint motion improved from 34 to 62°. Three prostheses needed a re-operation (one implant exchange and two arthrodeses). Radiologically, mean implant subsidence was 0.2 mm for both proximal and middle phalanges, without resorption at the joint anchor. Osteointegration occurred in 15 implants. Reliability of the bone resorption classification was moderate to excellent. On average, seven of 20 zones had a mean resorption index >1, indicating bone resorption, and resorption was noted around six of the protheses. Conclusion: With the SLFJ arthroplasty, proximal interphalangeal joint pain decreased, motion preservation was comparable with that for other implants and good osteointegration and radiological outcomes were obtained at mid-term follow-up. A validated scoring system for bone resorption was created, which can be used in other studies. Level of evidence: IV
Wong et al. (Wed,) studied this question.