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Cause of AVN—trauma
Epidemiology
Osteonecrosis is said to occur in 13% to 50% of cases of fracture of the scaphoid.
Anatomy
The blood supply of the scaphoid is primarily from the radial artery via the artery to the dorsal ridge of the scaphoid.
The proximal pole of the scaphoid relies entirely on this interosseous blood supply.
Pathophysiology
Low-energy falls from a standing height were most common (40.4%).
Males are significantly more likely to sustain their fracture after a high-energy injury.6
Clinical history
Scaphoid fractures are commonly seen in young, healthy individuals and may occur as a result of a fall on the outstretched arm or a forced dorsiflexion injury of the wrist.2
Physical examination
A reliable correlation exists between scaphoid fracture and pain provoked by deep palpation at the volar tubercle of the scaphoid, which is the first bony prominence distal to the volar distal radius. Scaphoid fracture is not very likely when tubercle palpation does not provoke pain in the snuffbox.
Special provocation maneuvers
Watson (scaphoid shift) test—The patient sits with the forearm pronated. The examiner takes the patient’s wrist into full ulnar deviation and extension. The examiner presses the patient’s thumb with his/her other hand and then begins radial deviation and flexion of the patient’s hand.
Scaphoid stress test—The patient sits while the examiner holds the patient’s wrist with one hand, with the examiner applying pressure with his/her thumb over the patient’s distal scaphoid. The patient then attempts radial deviation of the wrist.
Classification/imaging
A computed tomography bone scan in the long axis of the scaphoid is the best means of differentiating between stable and unstable fractures. Type B fractures should be corrected operatively (Table 22.2).7
Preiser’s disease
Preiser’s disease is a rare condition where ischemia and necrosis of the scaphoid bone occur bilaterally without previous fracture. The lack of perfusion to the proximal pole is often associated with prolonged use of corticosteroids or chemotherapy. X-ray and magnetic resonance imaging (MRI) are used to confirm diagnosis.
Classification/imaging
Staging of Preiser’s (Table 22.3)
Treatment
Initial treatment is immobilization
There are two surgical procedures to treat Preiser’s disease.
Proximal row carpectomy (PRC), which is the removal of the proximal row of carpal bones (scaphoid, lunate, and triquetrum)
Four-corner fusion with scaphoid excision, which is the removal of the scaphoid bone and fixing of the remaining wrist bones using a “spider plate” or wires (Figure 22.1)8,9
TABLE 22.1 Risk of Avascular Necrosis According to Gelberman and Gross1 | |||||||||
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TABLE 22.2 Scaphoid Fracture—Herbert Classification | ||||||||||||||||||||||||||||||||||||
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TABLE 22.3 Preiser Disease Classification38 | ||||||||||||
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 FIGURE 22.1 Four-corner fusion, x-rays on anteroposterior (A) and lateral (B) views. |
Kienbock’s disease
Epidemiology
This disease most commonly occurs in the dominant hand of males between the ages of 18 and 40 years.
It is estimated to occur in 2.5% of the population.8
Anatomy
80% of lunates receive their blood supply from both palmar and dorsal sources.
The dorsal radiocarpal arch delivers blood from the dorsal aspect of the hand.
The palmar radiocarpal and intercarpal arches deliver blood from the palmar aspect of the hand.
There are three major intraosseal anastomotic patterns of the lunate, named I, X,Y after their appearance.
Each of the patterns has a consistent prevalence in the population (Figure 22.2).Related posts:
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