Scapular dyskinesis and sick syndrome in patients with chronic type III acromioclavicular dilocation

Purpose: The aim of this study was to evaluate if patients with chronic type III acromio-clavicular dislocation develop a scapular dyskinesis, and eventually a SICK syndrome. Material and Methods: Of 34 (mean age: 47) patients with chronic dislocation (mean FU 28 months), we studied scapulo-thoracic motion basing on protocol described in Kibler's and in Burkhart's studies. We evaluated scapular position with arms at rest and abducted and internally rotated. A radiograph in AP view with the abducted aims was also performed. We applied the "SICK Scapula Rating Scale" to patients who had scapular dyskinesis, inferior medial border prominence and coracoid pain and malposition. Shoulder function was assessed with Constant Score and Simple Shoulder Test. Results; Ofthe34 patients, 24 (70.6%) had a scapular dyskinesis with arm at rest and 14 of these (58.3%) had a SICK syndrome. The mean "SICK Scapula Rating Scale" score was 6.9 points. At clinical and radiological examination with arms abducted at 90°, scapular dyskinesis was confirmed in 61.7 % and 64.7 % of patients, respectively (p>0.05). Constant Score was 83% and 91% for the involved and the contralateral side. The percentage was 75% and 88% in patients with and without dyskinesis, respectively (p<0.05) ; tlie mean value of Simple Shoulder Test was 8/12 and 10/12. Conclusion: Chronic type III AC dislocation causes scapular dyskinesis in 70.6% of the latter, 58.3% develop a SICK syndrome. Dyskinesis might be due to a) weakness and inflexibility of shoulder girdle muscles ; b) lost of the stable fulcrum of the shoulder girdle represented by the AC joint ; c) superior shoulder pain. Constant score and SST resulted lower in patients with dyskinesis. Initially rehabilitation program could be recommended. If satisfactory results are not obtained, surgical procedures for chronic dislocation may be proposed.