The Vascular Anatomy of the Capitate: New Discoveries Using Micro-Computed Tomography Imaging.

PURPOSE: To study the intraosseous 3-dimensional microvasculature of the capitate bone using a novel high-resolution micro-computed tomography (µCT) imaging technology, and to examine the blood supply as it relates to the most common fracture types. METHODS: Ten cadaveric wrists were injected with a lead-based contrast agent. The capitates were harvested and imaged using a µCT scanner. The intraosseous vascularity was incorporated into a 3-dimensional image. We measured the vascular pattern as well as the vessels' cross-sectional area, number, and distribution. An average capitate fracture line was calculated using clinical data from 22 patients with capitate fractures. The fracture line was projected on the representative capitate to assess its relation with the nutrient vessels' entry points. RESULTS: The capitate is a well-vascularized carpal supplied by dorsal and volar vascular systems that anastomose in 30% of cases. There was no predominance of one vascular system over the other. Most vessels enter the capitate at the distal half and supply the proximal pole in a retrograde fashion. In addition, most specimens (70%) also had at least one vessel entering the proximal pole through the volar capitate ligaments and supplying the proximal pole directly. The average fracture line had an oblique orientation, and 90% of the specimens had a blood vessel entering proximal to that line. CONCLUSIONS: This µCT vascular study further verifies that the capitate receives most of its vasculature in a retrograde fashion, but the study also shows that most capitates have vessels supplying the proximal pole directly. These findings might explain why most capitate waist fractures do not progress to proximal pole avascular necrosis. CLINICAL RELEVANCE: This study characterizes the microvasculature of the capitate and might shed light on processes involved in bone healing and the etiology of capitate avascular necrosis.

Osteoarticular pedicle flap from the capitate to reconstruct traumatic defects in the head of the proximal phalanx.

PURPOSE: To describe the reconstruction of traumatic defects in the head of the proximal phalanx using an osteoarticular pedicle flap from the capitate. METHODS: From January 2004 to December 2007, we treated 15 patients with traumatic defects of the head of the proximal phalanx at our institution. All of these injuries involved 1 condyle of the proximal phalanx. There were 11 male and 4 female patients; the mean age was 32 years. The injuries occurred in the index (n = 6), middle (n = 7), and ring (n = 2) fingers. At the final follow-up, we assessed space narrowing of the proximal interphalangeal joint and flap necrosis using plain radiography. We measured active motion and pinch and grip strength of the hand and compared all measurements with those on the opposite side. Patients rated injured-joint pain and donor-joint pain using a visual analog scale. We assessed hand function using the Disabilities of the Arm, Shoulder, and Hand scale. RESULTS: Patient follow-up averaged 52 months. At the final follow-up, we noted narrowing of the proximal interphalangeal joint in 3 cases, but we observed no flap necrosis. The mean active motion arc of the injured and opposite proximal interphalangeal joints was 50° and 96°, respectively. The mean pinch strength of the injured and opposite hands was 5.8 and 6.5 kg, respectively. The mean grip strength of the injured and opposite hands was 39 and 40 kg, respectively. We noted mild recipient joint pain in 6 patients and mild donor joint pain in 1 patient. The mean score of the Disabilities of the Arm, Shoulder, and Hand questionnaire was 9. CONCLUSIONS: We used an osteoarticular pedicle flap from the capitate to resurface traumatic defects of the head of the proximal phalanx. This approach is acceptable for restoring the contour of the phalangeal head.

Vascularized capitate transposition for advanced Kienböck disease: application of 40 cases and their anatomy.

Based on anatomic study, the vascularized capitate transposition to replace excised necrotic lunate was designed and applied in 40 cases of advanced Kienböck disease. It includes excision of the necrotic lunate and proximal shift of the vascularized capitate. The blood supply of the transposed capitate is provided by the dorsal branch of the anterior interosseous artery. Bone union occurred radiographically, and no postoperative capitate necrosis occurred in all cases after 6 weeks. Twenty-three cases were followed up for 1 year. No residual wrist pain existed in the range of motion, but limited residual wrist pain existed in labor work. The arc of motion ranged on average from 35 degrees of flexion to 45 degrees of extension. The grip power of the affected hand reached on average 70% compared with the contralateral. The authors conclude the vascularized capitate transposition is a reliable alternative for advanced Kienböck disease.