Site of the fracture in scaphoid has been related to union rate.. Reported rate of fractures in scaphoid is [For a quick reference to scaphoid anatomy please refer here]
- Waist fractures – 80%
- Proxial pole - 15%
- Tuberosity - 4%
- Distal articular fractures – 1%
The scaphoid bone has its blood supply from distal to proximal direction. Scaphoid branches of the radial artery enter the dorsal ridge and supply 70% to 80% of the bone, including the proximal pole. The other group of vessels enters the scaphoid tubercle and supplies only the distal 20% to 30% of the bone.
Therefore, in cases with fractures through the waist and proximal third, the vascular supply would be restored only with fracture healing.
Herbert and Fisher classification serves as guide to treatment of scaphoid fractures. It is given below.
Type A: Stable Acute Fractures
These are incomplet fractures which unite rapidly with minimal treatment
Type A1: Fracture of tuberosity
Type A2: Incomplete fracture through waist
Type B: Unstable Acute Fractures
These fractures are likely to displace in plaster.Delayed union is common and internal fixation is the treatment of choice
Type B1: Distal oblique fracture
Type B2: Complete fracture of waist
Type B3: Proximal pole fracture
Type B4: Transscaphoid-perilunate fracture dislocation of carpus
Type B5: Comminuted fractures
Type C: Delayed union
There is a widening of the fracture line, formation of cysts adjacent to the fracture ande proximal fragment becomes relatively dense.
Type D: Established nonunion
Type D1: Fibrous union
Type D2: Pseudarthrosis
Fibrous union can occur after conservative treatment. It is a stable non union with minimal deformity and variable cystic change. It may progress to pseuarthrosis in time which is hallmarked by unstable progressive deformity and leads to development of osteoarthritis.