Malunion deformity of the forearm: Three-dimensional length variation of interosseous membrane and bone collision.

Abstract

It remains unclear to what extent the interosseous membrane (IOM) is affected through the whole range of motion (ROM) in posttraumatic deformities of the forearm. The purpose of this study is to describe the ligament- and bone-related factors involved in rotational deficit of the forearm. Through three-dimensional (3D) kinematic simulations on one cadaveric forearm, angular deformities of 5°in fourdirections (flexion, extension, valgus, varus) were produced at twolocations of the radius and the ulna (proximal and distal third). The occurrence of bone collision in pronation and the linear length variation of sixparts of the IOM through the whole ROM were compared between the 32 types of forearm deformities. Similar patterns could be observed among fourgroups: 12 types of deformity presented increased bone collision in pronation, 8presented an improvement of bone collision with an increase of the mean linear lengthening of the IOM in neutral rotation, 6had an increased linear lengthening of the IOM in supination with nearly unchanged bone collision in pronation and 6types presented nearly unchanged bone collision in pronation with a shortening of the mean linear length of IOM in supination or neutral rotation. This kinematic analysis provides a better understanding of the ligament- and bone-related factors expected to cause rotational deficit in forearm deformity and may help to refine the surgical indications of patient-specific corrective osteotomy.