Reconstruction of swan neck deformities after proximal interphalangeal joint arthroplasty

The authors report the use of a single slip of the flexor digitorum superficialis (FDS) as a hemitenodesis through the A2 pulley in treating swan neck deformities after previous unconstrained proximal interphalangeal joint (PIP) arthroplasty.

A retrospective chart review was undertaken to identify non-constrained PIP joint arthroplasties that underwent a subsequent soft tissue hemitenodesis for swan neck deformities. The range of motion (ROM), implant design, preoperative diagnosis, and surgical approach were collected. The Michigan Hand Outcomes Questionnaire and patient satisfaction questionnaire were collected.

There were 12 patients with 14 procedures reviewed. There were seven surface replacement arthroplasties (SRA) (cobalt chrome on polyethylene) and eight pyrocarbon prostheses. The primary diagnosis for the initial joint arthroplasty was osteoarthritis (8), post-traumatic (2), and rheumatoid arthritis (5). The primary dorsal approach was a longitudinal split in eleven cases, Chamay in two, and unknown in one case. Nine of the 14 revision procedures had a concomitant dorsal approach to the joint. The average final position intraoperatively was 24.2° of flexion (range 15°-40°). Final ROM was 39° with average follow-up of 30 months. The average postoperative radiographic position was 20.3° flexion with an average of 24.8° hyperextension preoperatively. There was one failure secondary to implant loosening requiring fusion.

For patients with a swan neck deformity after PIP arthroplasty, a FDS hemitenodesis provides a treatment option with a low revision rate, retained motion, and maintenance of the original implant with no shortening of the digit.