[Z-plasty and rerouting of the biceps tendon with interosseous membrane release to restore pronation in paralytic supination posture and contracture of the forearm].

OBJECTIVE

Reduction of paralytic supination posture and contracture of the forearm. Improved spontaneous posture of the paralyzed arm with a more normal anatomic relationship of ulna and radius. Improvement of the activities of daily living, especially activities requiring active pronation (eating, dressing, writing). Prevention of recurrence or increase of the deformity during the growth period in obstetric brachial plexus palsy. Partly restoration of active pronation.

INDICATIONS

Unopposed supination by the biceps in the presence of paralysis of the pronators as a result of --brachial plexus palsy, --poliomyelitis, --quadriplegia, --paralysis from other causes.

CONTRAINDICATIONS

Ongoing spontaneous or postoperative nerve regeneration and possible improvement of paralyzed pronators. Posttraumatic or degenerative ankylosis of the elbow joint; the extent of the preoperative passive pronation determines the postoperative result. Insufficient power (< M(4)) of the triceps (inadequate triceps function can lead to a flexion contracture of the elbow).

SURGICAL TECHNIQUE

After exposure of the biceps tendon a long Z-plasty is used to lengthen the tendon and allow its distal segment to be rerouted around the neck of the radius mediolaterally. The tendon ends are sutured. The technique allows the biceps to become a pronator instead of a supinator while preserving its original function of elbow flexion. In case of interosseous membrane contracture a release of the membrane is necessary.

POSTOPERATIVE MANAGEMENT

Immobilization in an upper plaster cast or Gilchrist bandage with the elbow in 90 degrees flexion and the forearm in neutral rotation or pronation, no extension below 90 degrees flexion/no supination for 6 weeks. Passive and active exercises of elbow extension, flexion and pronation until the maximally possible range of motion has been reached (12-18 months); dynamic pronation orthosis, if needed.

RESULTS

Eleven children with obstetric brachial plexus palsy and an average age of 6 years (4-12 years) were operated. In eight cases, besides rerouting of the biceps tendon, a release of the interosseous membrane was performed. Average follow-up time is 36 months (10-55 months). In all patients, an improved and more normal spontaneous posture of the paralyzed forearm resulted: difference of forearm position/increase of pronation 87 degrees (70-100 degrees). 91% of the patients reached an active pronation at least to neutral rotation, 46% were able to pronate up to 30 degrees and more.