The aim of our study was to assess, for the first time in a large study, whether there are radiological features of the acromioclavicular joint (ACJ) which vary with age or between genders and side. Clinical experience suggested that there was no clear correlation between the radiological features and symptoms arising from the ACJ. Therefore we also aimed to test the null hypothesis that there are no consistent radiological features which correspond with the need for surgical excision of the ACJ.

We analysed 240 shoulder radiographs, divided into male and female, left and right shoulders, and decades from 20 to 80 years inclusive. At the ACJ the presence of sclerosis, osteophytes, cysts and lysis were recorded, and the width of the joint measured.

These same parameters were assessed on the pre-operative radiographs for a group of 100 patients by a blinded observer. Fifty had undergone ASD (arthroscopic subacromial decompression), and 50 ASD with ACJ excision. These two groups were age matched. Statistical analyses were performed.

There was no statistical difference between any of the parameters for gender or side however with increasing age there was a significantly increased incidence of joint space narrowing and increased features of osteoarthrosis. When comparing the matched ASD and the ACJ excision groups it was found that the presence of medial sclerosis (p = 0.016) and superior clavicular osteophytes (p = 0.016) were more common in the ACJ excision group.

We concluded that there is a change in the radiological features of the ACJ with increasing age but not between sides or gender. The null hypothesis is upheld. Only 2 parameters, namely medial acromial sclerosis and superior clavicular osteophytes, are radiological features which correlate with a symptomatic acromioclavicular joint. These have poor sensitivity and specificity and therefore should not be used as a test.