Vascularised Bone Grafts for Treatment of Scaphoid Nonunion: a Case Series Study

The scaphoid is the most commonly fractured carpal bone accounting for 60% of fractures. A number of case series have identified a 10%-15% nonunion rate. Scaphoid nonunion refers to a spectrum of failed healing, each of which requires a tailored approach.

Subsequent to non-union, degenerative changes with the formation of cysts, bony resorption with loss of bone stock and the development of apex dorsal angulation or the humpback deformity may occur leading to scaphoid non-union advanced collapse (SNAC) of the wrist and the formation of a proximal pole which extends with the lunate.

This has serious functional implications for the patient in terms of wrist range of movement, grip strength and general activities of daily living . The management of nonunion has remained controversial since the last century.

Bone grafting has been performed since the late 1920s with positive results. The importance of vascularity was enforced by finding that in the presence of avascular necrosis ( AVN ), conventional non vascularized bone grafts ( NVBGs) could only achieve a 47% union rate . However, in the absence of AVN, these NVBGs could achieve union rates of 94% .

There was growing consensus that new techniques were required to address the shortfall, and accordingly, vascularized bone grafting (VBG) techniques stemmed from this. It was widely believed that providing adequate blood flow would help treat cases of non-union . Several studies demonstrate that VBGs accelerated bone healing by preserving osteocytes and preventing the slower creeping substitution and were able to increase blood flow and superior mechanical properties in VBGs as opposed to NVBGs . VBGs could be further classified into pedicled or free VBGs. Pedicled VBGs involve isolating a segment of bone local to the defect and maintaining the blood supply to this segment of donor bone which is then fixed into the recipient site. This requires a good stock of donor bone in close proximity to the defect. Free VBGs involve detaching a segment of bone with its vascular bundle from a donor site and anastomosing this to recipient vessels with the fixation of the donor bone to recipient bone.This study hypothesis that VBGs should be used in all cases of humpback deformity , proximal pole fracture , AVN and cystic degeneration from the start.