Magnetic resonance imaging of the humpback scaphoid: the technique and a mathematical performance evaluation.

Surgical treatment of scaphoid nonunion and malunion with excessive intrascaphoid angulation (humpback deformity) usually involves a bone graft that is intended to correct the deformity. The volar bone graft length determines the degree of angular correction and scaphoid elongation. It is recommended that the length of the graft be determined by careful preoperative measurement of the deformity. Previous imaging techniques are inherently limited. The present paper describes a technique using three-dimensional magnetic resonance imaging. Scaphoid fracture angulation is calculated from measurements of comparable sagittal slices of the patient's fractured and normal scaphoid. Optimal bone graft length is determined by using simple trigonometric principles. Magnetic resonance imaging provides additional important information regarding vascularity of the proximal pole and the status of the periscaphoid ligaments and hyaline cartilage. Mathematical performance evaluation indicates that this technique is a promising method for planning reconstructive surgery of the scaphoid.