Axillary nerve injury following recurrent shoulder dislocation

lt is well known that a traumatic or atraumatic shoulder dislocation (SD) may be associated with an axillary nerve injury and that neurological function spontaneously recovers in some 90% of the cases. However, the available information in this regard refers only to primary dislocation. No studies have analyzed the prevalence of axillary nerve injury following a recurrent SD. Our study was performed to determine the prevalence and evolution over time of axillary nerve injury following recurrences of anterior SD. Material and methods. We reviewed the clinical records of 742 patients treated from 1988 to 1991 for a primary anterior SD. The patients were aged 2 to 89 years (mean 41 years); 142 (19.1%) were older than 60 years at the time of dislocation. Eighty-one patients were lost at follow-up and 15 had died during the follow~up period. Of the remaining 646 patients, 374 had one or more recurrent dislocations. We examined the clinical records of the redislocators and registered those who had an axillary nerve injury following a recurrence. The diagnosis of nervous injury was based on the clinical evaluation and documented by EMG studies, performed three weeks after the dislocation in all patients with a clinical suspicion of axillary nerve inury. At the time of this study the patients who had a nerve lesion were interviewed and examined. Results. During the follow up period, 6 (1.6%) patients had an axillary nerve injury following a dislocation and in all, the lesion was a neurapraxia. No patients had nerve injury at the time of the primary dislocation and, in all 6 cases, the injury occurred following the first recurrence. The prevalence was 6.2% (2 cases) in the group of 32 patients who were older than 60 years at the time of the primary dislocation and 1.1% (4 cases) in the 342 who were younger. Of the patients in the latter group, one had an associated radial nerve lesion. The nerve function completely recovered a mean time of 5 months (2.3 to 6.3 months) after the redislocation. Discussion. Axillary nerve injury is not uncommon in primary shoulder dislocation. lt may consist in neurapraxia, axonotrnesis and even neurotmesis. ln our series. 1.6% of patients with one or more recurrences of SD sustained a neurapraxia of the axillary nerve (and in one case also of the radial nerve). Probably. more severe nerve lesions do not occur in redislocators, since the SD is often reduced by the patient a short time after its occurrence, and this decreases the periood of traction- compression of the nerve by the humeral head. An alternative explanation might be the lower energy of the trauma responsible for a redislocation compared with a primary dislocation. ln all our cases. the nerve lesion occurred during the first recurrence. This is possibly due to the fact that the first recurrence often occurs following a more severe trauma compared with the subsequent dislocations. Conclusions. This is the first study showing that an axillary nerve injury occurs in a small proportion of patients undergoing shoulder redislocations, which was always the first one in our series. The nerve lesion is more frequent in elderly patients and spontaneously tends to recover.