Tenodesis of extensor digitorum in treatment of brachial plexus injuries involving C5, 6, 7 and 8 nerve roots

Dynamic tenodesis of the finger extensors to improve hand function after brachial plexus injury

The term "plexic hand" refers to hand and wrist involvement in traumatic brachial plexus injuries and to remaining deficits after nerve surgery has been performed. From January 2000 to March 2008, reconstructive surgery (dynamic tenodesis) was performed on seven patients with C5, 6, 7, and 8 nerve root lesions of the brachial plexus to restore wrist and finger extension. This procedure has been used in seven patients (one female). Two patients with a lesion of the brachial plexus sustained a fracture of the affected limb. Preliminary nerve repair operations were required in four cases. One hundred percent (seven) of the patients had improved function following dynamic tenodesis. The extension angle of the wrist joint on grip was 19° on average. The flexion angle of the wrist joint needed to produce MP joint extension was 24.3° on average. A new dynamic extensor tenodesis technique is proposed. The extensor digitorum communis tendons are looped through dorsal carpal retinaculum ligament and sutured to themselves. Our results demonstrate that the extensor dynamic tenodesis procedure is an effective and simple means of restoring grip function for patients with C5, 6, 7, and 8 nerve root lesions.

Extensor tenodesis for plexic hands with C7 to T1 or C8, T1 root avulsions: a new technique

In C7 to T1 or C8, T1 root avulsion palsies, restoration of finger active extension is not possible. Only tenodesis may restore hand opening in active wrist flexion. Many techniques have been described to restore this motion. In routine techniques, extensor tendons are fixed on radius or sutured on dorsal retinaculum. However, in these procedures, progressive tendon lengthening or ruptures may occur and salvage procedure may be difficult to perform. Therefore, we proposed a new extensor tenodesis technique. The extensor digitorum communis tendons are sutured on the paralyzed flexor digitorum superficialis tendons through interosseous membrane. This procedure allows performing a strong tendon to tendon suture more resistant than radius or retinaculum fixation. As other tenodesis techniques, wrist flexion has to be active to obtain hand opening.

[Extensor tenodesis to the retinaculum extensorum: anatomic and biomechanical study]

INTRODUCTION

The extensor tenodesis is a direct dynamic tenodesis which is activated by wrist flexion due either to hand weight or flexor carpi radialis. This tenodesis is usually performed to the distal radius, but it is possible to fix EDC (extensor digitorum communis) to the retinaculum extensorum.

MATERIAL AND METHODS

Biomechanical study concerned 12 anatomical subjects (24 wrists). The biometric and radiological analysis of retinaculum displacement distalwards was made under low (1 kg) and moderate (6 kg) pulling. Surgical clips were placed on the proximal and distal limits of the retinaculum in order to study their positions on roentgenograms.

RESULTS

Average width of the retinaculum was 19 mm. Average movement under 1 kg drive was 6 mm and 8.6 mm under 6 kg drive. X-rays showed that the proximal border of the retinaculum was always located proximally to the wrist rotate centre, whatever the traction.

DISCUSSION

We found the same anatomical features described by different authors, except for the width of the retinaculum. Our study suggests that the retinaculum is strong enough to support a surgical tenodesis.

Treatment of brachial plexus injury

A brachial plexus injury is the most severe nerve injury of the extremities. To achieve good results from treatment, correct diagnosis and early nerve repair are mandatory. The brachial plexus should be explored as early as possible if there is an incised wound, if clinical findings or diagnostic imaging indicate that at least one root is avulsed, if there is damage to the subclavian artery, and if there is total-type injury. With an upper-type injury with no clinical signs of a preganglionic lesion, the patient should be treated conservatively for 3 months and if there are no signs of recovery, then the brachial plexus should be explored. During this exploration, recording of the spinal cord evoked potential (ESCP) or the somatosensory evoked potential (SEP) is mandatory to determine the site of injury. Nerve grafting is indicated for a rupture in the root demonstrating a positive ESCP or SEP potential, in the trunk or in the cord. Exploration of the brachial plexus should be extended distally as far as possible to achieve good results after nerve grafting; when this was done more than M3 (MRC grading) power of the infraspinatus, deltoid, and biceps was achieved in more than 70% of our 32, 30, 33 patients, respectively. Results of nerve grafting for the forearm muscles have been very poor. Intercostal nerve transfer is recommended to restore elbow flexion in root avulsion type of injury, with elbow flexion to more than M3 being regained in 70% of our 221 patients. The best results of intercostal nerve transfer were achieved in patients younger than 30 years who received the operation within 6 months after injury. Motor recovery of hand function after intercostal nerve transfer was poor but protective sensation was restored in fingers innervated by the median nerve. The recommended treatment for each type of injury is described according to the results achieved.