SCAPULOTHORACIC ARTHRODESIS FOR UNIQUE PARALYSIS OF THE SERRATUS ANTERIOR

Abstract

Purpose: The serratus anterior, innervated by the Charles Bell nerve, contributes to dynamic abduction and elevation of the shoulder by stabilising the scapula on the thorax. Abduction and elevation beyond 90° or movement of the spinal border of the scapula is impossible in case of serratus anterior paralysis.

Material and methods: This series included 16 patients with traumatic damage to the Charles Bell nerve leading to unique paralysis of the serratus anterior. Mean age of the patients at diagnosis was 27.5 years. Nine patients underwent scapulothoracic arthrodesis or scapulopexia and seven patients were not operated due to spontaneous total or partial recovery.

Results: Initial elevation in the non operated group was 125°. At five years elevation was 145°, Constant score was 85, and shoulder abduction force was 12 kg (83% of the contralateral force). Final outcome was very good in four patients, good in one, fair in one and poor in one (the fair and poor outcomes involved severe pain for one and major loss of force for the other). Preoperative elevation in the operated group was 95°, reaching 104° at last follow-up. At four years, elevation was 104°, Constant score was 75, and shoulder abduction force was 9 kg (72% of the contralateral force). One case of infection required revision and healed satisfactorily. Outcome was very good in six patients and good in three.

Discussion: Several types of treatment can be proposed: non-surgical care, muscle transfer basically with the pectoralis major, and scapulothoracic arthrodesis. The principal series reported in the literature on scapulothoracic arthrodesis concern patients with fascioscapulohumeral dystrophy and are not comparable with our series. It would be possible to compare our patients with series of post-trauma paralysis using muscle transfer which have given good results for mobility but limited improvement in global muscle force. In our patients, scapulothoracic arthrodesis gave good results in terms of muscle force, pain and overall shoulder function; mobility was fixed by the position of the scapula in the arthrodesis. We advocate this method for the treatment of serratus anterior paralysis mainly in manual labourers.