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Vascularized Dorsal Capsular Bone Grafting for Proximal Pole Scaphoid Nonunions with AVN
Seth D Dodds, MD1; Shannon Fitzpatrick, MD2; Cynthia Tsai, BS2
1University of Miami, Miami, FL, 2Yale University, New Haven, CT

Introduction: Fracture fixation is frequently tenuous when the scaphoid proximal pole is a small avascular nonunited fragment. We hypothesized that the addition of scaphocapitate screw fixation to standard scaphoid screw nonunion repairs would improve healing rates.

Methods: We retrospectively reviewed ten patients with scaphoid proximal pole fracture nonunions that were treated with a vascularized dorsal capsular graft as described by Sotereanos(1), scaphoid screw fixation, and temporary scaphocapitate fixation. Two patients were lost to final follow-up. Scaphoid proximal pole nonunions were debrided and bone grafted with cancellous autograft. A dorsal trough was created in the scaphoid for the dorsal capsular vascularized bone graft. The scaphoid nonunion was then secured with a scaphoid screw placed down the central axis of the scaphoid. Next, percutaneous scaphocapitate fixation of the midcarpal was performed to reduce flexion forces at the fracture site. All patients were prescribed an ultrasound bone stimulator until there was radiographic evidence of healing, defined as >50% bone bridging on CT scan.

Results: Our case series included eight males and two females with an average age of 22.5. All patients had proximal pole fractures of the scaphoid with avascular necrosis as diagnosed on CT scan based on bone density. The average time to radiographic union for patients with proximal pole necrosis was 5.5 months, with 2 patients taking up to a year to heal before removal of their scaphocapitate screws. The average wrist flex/ext for patients was 42.5/47.5 after scaphocapitate screw removal compared to pre-op flex/ext of 45.0/ 36.7. Healing was confirmed on CT scan in 8 of 10 patients, in the other 2 patients healing was confirmed on radiographs and intra-operative fluoroscopy at the time of screw removal. Complications included 2 patients with radial sensory nerve hypersensitivity that did not completely resolve related to the scaphocapitate screw insertion and/or subsequent removal.

Conclusions: While we did achieve healing in all of our patients, we recognize that the time to union was lengthy in this group. In fact, one patient, who took over a year to heal, had a CT scan at six months showing no more than 25% bridging bone. Prior series(1) without scaphocapitate screw fixation found 8 of 10 proximal pole nonunions with AVN healed, but no other complications. Vascularized, dorsal capsular grafting with temporary scaphocapitate fixation creates a powerful combination of surgical treatment for a very challenging subset of scaphoid proximal pole fracture nonunions with avascular necrosis.

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