A 46-year-old man presented 1 week after sustaining an open injury to the right thumb. He had injured the thumb while using a saw to cut a flagstone. He had received emergency care in a community hospital, where intravenous antibiotics had been promptly administered, and debridement and irrigation had been performed in the operating room. The wound had been sutured and the thumb was splinted. The patient was then referred to our hospital.
The wound margins appear to be healed and closed. There are no signs of infection. The thumb tip is warm and well perfused. Normal sensation was noted. The digit was very unstable because of the fracture. Tendon function was poor.
Initial radiographs reveal a fracture of the proximal phalanx of the thumb with segmental bone and articular surface loss, leaving the proximal half of the proximal phalanx (▶Fig. 39.1).
One should first realize that this problem could have been treated by immediate internal or external fixation at the initial time of injury. However, large segmental bone defects in a viable digit may require structural bone grafting. The use of a free vascularized bone graft requires microsurgical expertise, which may not be readily available. A nonvascularized structural bone graft within the same extremity as the injury has the advantage of only involving a single surgical field, allowing the use of regional anesthesia. Nonvascularized bone graft from the iliac crest has been used successfully for structural purposes in the phalanges.
Arthrodesis of the distal interphalangeal joint and thumb interphalangeal joint is an effective surgical procedure for restoring hand function and joint stability. Arthrodesis can be done using cannulated headless screws; these have the theoretical benefit of being completely intraosseous, thus avoiding hardware prominence while providing interfragmentary compression. As the distal phalanx of the thumb is larger than that of the other digits, we can use larger diameter implants for bone fusion in the thumb.
The patient is placed in the supine position, using a hand table. A dorsal longitudinal incision is made directly over the thumb. After exposing the base of the distal phalanx, the cartilage is curetted out, exposing the subchondral bone. A small K-wire is advanced in an antegrade fashion through the flexed distal phalanx, exiting through the tip of the finger in the midline. This wire is then advanced until the tip is just proximal to the surface of the distal phalanx. A nonvascularized rectangular corticocancellous anterior iliac crest bone graft is aligned with the distal phalanx, and the wire is advanced proximally into the bone graft. A cannulated headless screw of appropriate length is inserted to approximately half the length of the bone graft, taking care to maintain reduction of the fusion site. The proximal portion of the bone graft is aligned with the fragment of proximal phalanx. A small K-wire is then advanced in an antegrade fashion through the dorsal phalanx base until it reaches the bone graft. A second cannulated headless screw is inserted distally (▶Fig. 39.2).
Final fluoroscopic images are then taken, before wounds are closed with 5–0 nylon sutures. Bandages and a splint are then placed.
Sutures are removed at 10 days postoperatively. Hand therapy is not typically necessary. The patient is monitored until bony union occurs (▶Fig. 39.3). Thumb grip is restored and the patient returns to his professional activities (▶Fig. 39.4).