Pitfalls

• A humpback deformity of the scaphoid is a relative contraindication for a vascularized, pedicled bone graft because correction of the deformity is very difficult when performing the graft. Adequate correction of the deformity is more reliably accomplished from a palmar (Russe) approach with conventional trapezoidal corticocan-cellous bone grafting and Herbert screw fixation.

• The scaphoid nonunion may not be readily identifiable because the cartilage may be partially intact or fibrous tissue may be present.

Scaphoid Humpback Deformity
Figure 58—3. Computed tomography (CT) scan of a patient with a nonunion and humpback deformity.

(Fig. 58—4). If previous surgery has failed, a scaphoid nonunion should be classified one stage worse than suggested by its radiographic appearance.

Natural history studies of scaphoid nonunions suggest progression to wrist instability and subsequent wrist arthritis. Surgical treatment is usually indicated for patients with stages Dl and D2 regardless of the presence or degree of symptoms. Stages D3 and D4 have the presence of progressively more severe osteoarthritis, more loss of motion, and lower union rates. For patients with stages D3, D4, and D5 the patient's age, symptoms, occupation, and needs should be taken into consideration when deciding among conservative treatment, scaphoid reconstruction, and a salvage procedure. For patients with stage D5 who do not have significant osteoarthritis and do

Snac Scaphoid Stage

Likelihood of Healing +++-f Figure 58—4. Herbert's five stages of scaphoid nonunions.

not have a humpback deformity, a vascularized, pedicled distal radius bone graft can be considered. Some authors recommend vascularized grafts for patients with stage D5 who have humpback deformities. However, correction of the carpal malalignment pattern is difficult, and the likelihood of success is less than for patients without a humpback deformity.

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Essentials of Human Physiology

Essentials of Human Physiology

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