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BACKGROUND: Scaphoid non-union can lead to functionally debilitating wrist arthritis. The use of the medial femoral condyle corticocancellous, vascularized bone graft has been described for microvascular reconstruction of scaphoid non-union in the setting of proximal pole avascular necrosis. Advantages of free, vascularized bone grafting include ease of volar placement and correction of humpback deformity as a result of detaching the vascular pedicle.
We hypothesize that a lateral humeral metaphyseal flap, based on the radial collateral artery or its posterior branch, could provide vascularized bone for use in microsurgical correction of scaphoid non-union with humpback deformity and proximal pole avascular necrosis.
METHODS: We sought to re-explore the anatomy of the lateral arm flap, the radial collateral artery and its blood supply to the lateral, distal humerus with the goal of defining the clinically relevant arteriovenous anatomy of the region, ease of dissection, pedicle length and diameter. Fresh cadaver dissections were performed after which arteriovenous anatomy was described and time to complete dissection, pedicle length and diameter and anatomic variability were recorded.
RESULTS: The distal extent of the deltoid, lateral intermuscular septum (LIS) and lateral humeral epicondyle were identified prior to the dissection. Upon incision along the LIS, a septocutaneous perforator was easily identified at approximately 10 cm proximal to the lateral humeral epicondyle. Dissection was carried out toward its bifurcation from the posterior branch of the radial collateral artery (PBRCA) and then along the PBRCA to its terminal periosteal extensions at the lateral humeral metaphysis. An osteotome was then used to complete the harvest of a 1.5 cm x 2 cm vascularized, corticocancellous bone graft. In total, the dissection took an average of 30 minutes to perform; average pedicle length was 5 cm and average pedicle diameter was 1.5 mm.
CONCLUSIONS: Vascularized grafts have been shown to be superior to avascularized bony constructs when bridging a large bony defect or in promoting union in the setting of avascular necrosis. With limited data available, results have been excellent with the medial femoral condyle (MFC) corticocancellous vascularized bone graft. Drawbacks to the MFC bone graft include: time to harvest, separate operative site and potential donor site morbidity. Understanding the limitations of a cadaver study, we propose that the lateral arm may become a suitable alternative to the MFC for its use in providing vascularized bone because of reliable anatomy, quick dissection, and tourniquet control within the same operative field.