Does cubitus varus cause morphologic and alignment changes in the elbow joint?

Abstract

In cubitus varus after pediatric supracondylar fracture, late development of trochlear deformity causing additional varus angulation and joint misalignment relating to late complications of the tardy ulnar nerve palsy or posterolateral rotatory instability have been suggested. However, it is unclear whether these morphologic and alignment changes of the elbow joint occur in cubitus varus. The object of this study was to investigate morphologic changes of the bones and alignment changes of the elbow joint in longstanding cubitus varus using 3-dimensional computer bone models created from computed tomography data. We studied 14 patients with longstanding cubitus varus after pediatric supracondylar fractures. Three-dimensional bone models of the bilateral humerus, radius, and ulna were created from computed tomography data. We compared the morphology and alignment of the elbow joint between the affected side and contralateral unaffected side. The posterior trochlea, distal part of the lateral capitellum, diameters of the radial head, and articular surface of the ulna in cubitus varus were larger than those of the contralateral elbow. In the ulna, the convex portion of the trochlear notch shifted laterally in cubitus varus. Joint alignment in cubitus varus was affected by a shift of the ulna to a more distal and medial position with external rotation and flexion. In longstanding cubitus varus, the morphology and alignment of the elbow joint are observed to differ from those of the normal side.