Hand Fractures

Scaphoid Fractures

ref: Gelberman etal "Fractures and nonunions of the carpal Scaphoid"
JBJS 71A:1560-1565, 1989

Blood supply:

From the radial artery both the dorsal and palmar branches but only two direct vascular leashes are observed entering the scaphoid
The most important of these are the scaphoid branches of the dorsal carpal branch of the radial artery entering the bone though the foramina along its dorsal ridge supplying 70 - 80% of the bone including the entire proximal pole
A second vessel or group of vessels from the palmar and superficial palmar branches enter the scaphoid in the region of its tuberosity to perfuse the distal 20 - 30% of the bone
The dorsal approach to the scaphoid places these vessels entering the dorsal ridge at highest risk

Pathology:

Approximately 30% of fractures of the middle third and nearly 100% of those of the proximal fifth are associated with osteonecrosis of the proximal pole

Treatment:

ref: Gellman etal "Comparison of Short and Long Thumb Spica casts for nondisplaced fractures of the carpal Scaphoid" JBJS 71A: 354-357, 1989
A prospective randomised clinical trial demonstrated a statistically significant advantage for treatment with a long thumb spica cast
Should be splinted in slight flexion and ulna deviation
Unstable (displaced fractures) should be internally fixed

Prognosis:

Undisplaced fractures united in 8 - 12 weeks when treated in a long thumb spica cast
Fractures of the distal 1/3 can be expected to unite in 6 - 8 weeks
middle 1/3 in 8 - 12 weeks
proximal 1/3 in 12 - 23 weeks

Complications:

Scaphoid non union ® OA develops in the adjacent carpal joints in more than 90% of cases within 5 yrs
This will be associated with discomfort in the majority of cases
Non-union ® carpal instability ® degenerative arthritis
Treatment:

Russe BG - 92% union rate ( iliac crest BG placed from volar side) (Matti = graft from dorsum- not done as risk to blood supply)
BG with fixation either K-wires or Herbert Screw

Late OA - difficult to treat- options include

Autograft eg costochondral
Allograft
Implant: silicone not used due to synovitis, hence titanium
scaphoid excision combined with intercarpal fusion
total wrist fusion

Scaphoid Malunion
can get markedly flexed scaphoid with a humpback deformity
osteotomy has been described to correct this - potential risks are of AVN of prox fragment

Dislocation of the MCP Joint of the Thumb:

Blocks to reduction include

Collateral ligament
Volar plate displaced into the joint
FPB or FPL tendons
Osteochondral fractures
Head button-holed through anterior capsule
Proximal phalanx button-holed through the extensor tendon