Supination contractures of the forearm in children occurs secondary to muscle imbalance across the forearm. There is relative weakness or paralysis of the flexor pronator mass and unopposed pull of the biceps and supinator. The contracture is initially dynamic but then becomes fixed as the interosseous membrane and surrounding structures tighten. The position of supination limits function as the majority of activities of daily living are performed in pronation. There have been a variety of surgical procedures recommended for correcting this awkward position and this study represents an experience using a distal ulnar osteotomy without fixation and a mid-radial osteotomy with plate fixation through this problem.
The cohort is relatively small consisting of 14 patients with an average age of 11 years. Diagnoses included 11 patients with brachial plexus palsy, 2 with poliomyelitis, and 1 with a Monteggia fracture malunion. This surgery was performed through two incisions. A small distal ulnar incision was made to accommodate an osteotomy without fixation. A standard mid-forearm volar Henry approach was perfomed to gain access to the radius. The radius was rotated and fixed within low-contact dynamic compression plate. Measurements of forearm rotation were assessed with elbow at 90° using a goniometer.
The mean preoperative forearm position was 80° of supination and the mean final postoperative position was 24° of pronation. Thus, the mean change in forearm rotation was 104°. There was 1 patient that developed a distal ulnar nonunion that was asymptomatic. There were no cases of compartment syndrome, nerve injuries, or fixation failure.
This series provides another alternative for treatment of a forearm supination contracture. Previous studies indicate the most efficacious manner to obtain maximum correction is a dual osteotomy via proximal radius and distal ulnar or a one bone forearm. The theoretical controversy with mid-radial osteotomy is loss of the radial bow during attempted rotation. However, the authors performed a concomitant distal ulnar osteotomy which appears to have prevented this problem.
Currently, a supple supination position is best treated by a biceps rerouting. A fixed contracture is more controversial. A variety of osteotomies have been recommended to maximize correction. Some of the osteotomies have been combined with an interosseous membrane release, which appears to be a constraining factor for regaining pronation. Small amounts of correction can be obtained by cutting the radius or ulna alone. Larger corrections require cutting both bones or creating a one bone forearm.