The Impact of Pronator Quadratus Origin Release on the Clinical Outcomes of Scaphoid Nonunion Patients Treated with Pronator Quadratus Pedicled Bone Grafts

Background/Objectives: A pronator quadratus pedicled bone graft (PQPBG) is a distal radius volar vascularized bone graft used not only for avascular necrosis of the lunate but also for scaphoid nonunion. Despite its potency and its possession of a muscular shield, this vascularized graft has a disadvantage in that the potential shortness of the muscular leash may limit the distal transfer of the bone graft. Releasing of the pronator quadratus (PQ) ulnar origin was used to enhance the distal mobility of the graft. We aimed to investigate the effect of a PQ release on the surgical outcomes of scaphoid nonunions that were operated on with the PQPBG technique. Methods: Patients with scaphoid nonunion that were treated with PQPBG from 2009 to 2020 were reviewed. Patient demographic characteristics, surgical notes, physical examinations, and radiological evaluation data were collected. Wrist range of motion, grip strength, modified Mayo wrist score, and Quick-DASH score were used to evaluate the outcomes. The included patients were divided into two groups based on the origin release status of their PQ, i.e., with and without release. Results: This study included 37 patients, 17 of whom underwent a PQ release and 20 of whom did not. The failure rates for the two groups were one and four patients, respectively, and there was no significant difference between them (p = 0.11). The postoperative mean wrist extension in the patients with a PQ release was significantly greater than that in the patients without a release (43.5 +/- 6.8 vs. 36.5 +/- 7.7, p = 0.0038). Although wrist flexion, ulnar deviation, radial deviation, mean outcome assessment scores, and grip strength were greater in the patients with a PQ release than in those without, no statistically significant intergroup differences were observed (p > 0.05). Conclusions: The PQPBG technique is a viable option for achieving bony union in patients with scaphoid nonunion, but it results in the postoperative restriction of wrist extension. PQ release during a graft transfer may have a favorable effect on both bone union and clinical outcomes.