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Scaphoid fractures and non-union

Scaphoid fractures are common carpal fractures, usually caused by a fall on an outstretched hand, and most often involve the scaphoid waist. Because the scaphoid has a predominantly retrograde blood supply, proximal fractures have a higher risk of avascular necrosis and non-union. Patients typically present with radial-sided wrist pain and anatomical snuffbox tenderness. Treatment depends on fracture location, displacement, stability, and vascularity. Scaphoid non-union occurs when a scaphoid fracture fails to unite, often because of delayed diagnosis, displacement, instability, or impaired blood supply. Untreated non-union may progress to scaphoid non-union advanced collapse (SNAC wrist) and secondary arthritis. Management may require internal fixation with bone grafting, with vascularized grafts considered in selected cases.

Scaphoid fractures are the most common fractures of the carpal bones and typically occur after a fall onto an extended wrist. The fracture most commonly involves the waist of the scaphoid, followed by the proximal pole and distal pole. Clinical features include radial-sided wrist pain, tenderness in the anatomical snuffbox, scaphoid tubercle tenderness, and pain with axial loading of the thumb. The scaphoid receives much of its blood supply from branches of the radial artery entering distally and dorsally, resulting in a predominantly retrograde blood supply to the proximal pole. This makes proximal pole fractures particularly vulnerable to avascular necrosis and delayed union or non-union. Plain radiographs with dedicated scaphoid views are the initial investigation, but occult fractures may not be visible early. MRI is highly sensitive for occult fractures, while CT is useful for assessing displacement, fracture configuration, union, and surgical planning. Stable, undisplaced fractures may be managed with cast immobilization, whereas displaced, unstable, proximal pole, or high-demand fractures may require internal fixation, commonly using a headless compression screw. Scaphoid non-union is generally considered when there is persistent failure of fracture healing over time, particularly with radiographic or CT evidence of a persistent fracture gap, sclerosis, cystic change, or deformity. Chronic non-union may produce a humpback deformity, carpal instability, and progressive degenerative change, eventually leading to SNAC wrist. Treatment of scaphoid non-union aims to restore scaphoid length and alignment, achieve union, and prevent carpal collapse. Options include internal fixation with cancellous or structural bone grafting, while vascularized bone grafts may be used in selected proximal pole non-unions or cases with compromised vascularity. Advanced degenerative disease may require salvage procedures rather than reconstructive fixation.

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