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A: acute stable (A1 tubercle, A2 nondisplaced waist). B: acute unstable (B1 distal oblique, B2 displaced waist, B3 proximal pole, B4 comminuted, B5 perilunate). C: delayed union; D: established nonunion. Unstable (B) often need fixation; D needs grafting + fixation.
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The scaphoid is the most commonly fractured carpal bone, accounting for approximately 60–70% of all carpal fractures and 2–7% of all fractures presenting to emergency departments. It is clinically important out of proportion to its size because: (1) it is frequently missed on initial X-ray (initial false negative rate up to 20–30%); (2) it has a precarious and retrograde blood supply that makes proximal pole fractures prone to avascular necrosis (AVN); (3) non-union, if untreated, leads to the `scaphoid non-union advanced collapse` (SNAC wrist) — a predictable pattern of progressive perilunate wrist arthritis. The Herbert classification (1984), developed by Tim Herbert and William Fisher, grades scaphoid fractures by their stability and the specific fracture pattern, and directly guides management.
| Herbert Type | Category | Fracture Description | Stability | Treatment |
|---|---|---|---|---|
| Type A1 — Distal pole avulsion | Type A = STABLE acute fractures | A fracture of the distal pole (the distal tubercle of the scaphoid) by avulsion; the radioscaphoid or scaphotrapeziotrapezoid ligaments avulse the distal tubercle; the articular surfaces of the scaphoid are not significantly involved; this fracture is distal to the main blood supply entry point | STABLE — the main scaphoid body is intact; the distal avulsion fragment is non-weight-bearing | Non-operative — thumb spica cast for 4–6 weeks; excellent healing potential (rich distal blood supply); non-union is rare for distal pole fractures |
| Type A2 — Incomplete waist fracture | An incomplete fracture through the waist of the scaphoid; the fracture does NOT cross the full width of the scaphoid; there is no displacement; the fracture is a `crack` in the cortex without full-thickness disruption; the scaphoid remains `stable` because the fracture is incomplete | STABLE — incomplete fracture; no displacement; cortex is not fully disrupted | Non-operative — thumb spica cast for 6–8 weeks; close radiological follow-up (risk of displacement if treated without immobilisation); good healing potential with conservative management | |
| Type B1 — Distal oblique fracture | Type B = UNSTABLE acute fractures | An oblique fracture through the DISTAL third of the scaphoid; the fracture line runs obliquely in the distal body; the fracture is more proximal than A1 but distal to the waist; may involve the scaphotrapezial joint | UNSTABLE — the oblique fracture line creates shear forces; the fragments tend to displace under load | Operative — Herbert screw fixation (headless compression screw); the screw is inserted under fluoroscopic guidance through the distal pole along the scaphoid axis; provides compression across the fracture; allows early mobilisation |
| Type B2 — Complete displaced waist fracture | A COMPLETE fracture through the WAIST of the scaphoid with DISPLACEMENT; the full width of the scaphoid is fractured and the fragments are displaced; the waist fracture is the most common scaphoid fracture pattern; when displaced (>1 mm step-off or >60° dorsal intercalated segment instability pattern), it is classified as unstable; the high AVN risk for waist fractures (from disrupted retrograde blood supply) combined with the instability makes this an important surgical indication | UNSTABLE — complete fracture with displacement; the fracture tends to angulate (humpback deformity) and displace under load; dorsal intercalated segment instability (DISI) deformity may develop | Operative — percutaneous or mini-open Herbert screw fixation; the `humpback deformity` (flexion deformity of the distal scaphoid fragment with volar collapse) must be corrected before screw insertion; if the humpback is corrected, the screw can be placed; the screw is placed along the central axis of the scaphoid from the distal pole | |
| Type B3 — Proximal pole fracture | A fracture through the PROXIMAL POLE of the scaphoid; this is the most critical subtype for AVN risk — the proximal pole has the most tenuous blood supply (entirely retrograde); any disruption of the dorsal entry vessels at the waist/proximal junction devascularises the proximal pole; even undisplaced proximal pole fractures carry a high AVN risk | UNSTABLE — the proximal pole fragment is small and has poor blood supply; even without displacement, the proximal pole is at high risk of AVN | Operative — Herbert screw fixation of the proximal pole; approach from the proximal pole (dorsal approach under scaphoscapholunate angle); the screw is placed from proximal to distal; very technically demanding due to small fragment size; AVN remains a risk even after anatomical fixation; MRI post-operatively monitors vascularity of the proximal pole | |
| Type B4 — Trans-scaphoid perilunate fracture-dislocation | A fracture of the scaphoid waist associated with a PERILUNATE DISLOCATION of the carpus; this is a high-energy injury where the scaphoid fracture is part of a complex perilunate ring disruption; the lunate dislocates from the radius while the proximal scaphoid fragment remains attached to the lunate (the `de Quervain` fracture-dislocation); this is a `greater arc` injury in the perilunate injury spectrum | HIGHLY UNSTABLE — the entire carpal architecture is disrupted; the proximal carpal row is dislocated; often associated with median nerve compression (from the anteriorly displaced lunate in perilunate dislocation) | URGENT operative management — open reduction of the perilunate dislocation + scaphoid fixation + intercarpal ligament repair (SL ligament in particular); median nerve decompression at carpal tunnel if present; typically through combined volar + dorsal approach; prognosis for wrist function is guarded | |
| Type C — Delayed union | Type C = Delayed union | A fracture that shows radiological evidence of incomplete healing at the expected time of union (typically beyond 12–16 weeks for waist fractures); there is fibrous or incomplete osseous union at the fracture site; a small sclerotic gap may be present; MRI shows persistent signal at the fracture with incomplete bridging callus | Potentially unstable — a delayed union may progress to established non-union if not treated | Operative — screw fixation ± bone grafting; for simple delayed union without AVN → percutaneous screw fixation alone may achieve union; for delayed union with humpback deformity → open reduction, deformity correction, bone graft, and screw fixation |
| Type D1 — Fibrous non-union | Type D = ESTABLISHED non-union | An ESTABLISHED NON-UNION of the scaphoid where fibrous tissue bridges the fracture site; the fracture has been present for >4–6 months with no healing; the fibrous tissue is mechanically weaker than bone but may provide some stability; MRI shows persistent T2 signal (fluid) at the fracture; no bridging bone callus | NON-UNION — persistent fibrous pseudarthrosis; will not heal without surgical intervention | ORIF + bone graft (Russe corticocancellous graft, iliac crest graft, or vascularised bone graft for AVN); anatomical reduction of humpback deformity is critical; screw fixation after grafting; vascularised bone graft (1,2-intercompartmental supraretinacular artery vascularised graft — the `1,2 ICSRA` graft) for non-unions with AVN of the proximal pole |
| Type D2 — Sclerotic non-union | An established non-union with SCLEROSIS — the fracture surfaces are eburnated (sclerotic dense bone); the fracture ends have become avascular and densely mineralised; the sclerotic fragments cannot revascularise; the non-union is `established and mature`; X-ray shows sclerotic fracture margins with loss of the fracture gap; there may be cyst formation in the proximal pole | ESTABLISHED NON-UNION with sclerosis — the sclerotic bone must be completely excised before grafting to allow biological union | ORIF with excision of sclerotic bone ends + vascularised bone graft (VBG) is typically required; for established proximal pole AVN with sclerosis → vascularised graft (1,2 ICSRA or Zaidemberg procedure — using the distal radius 1,2 ICSRA pedicle); for advanced SNAC wrist → salvage procedures (proximal row carpectomy [PRC] or four-corner fusion [scaphoid excision + lunate-capitate-hamate-triquetral fusion]) |
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