[Clinicopathological status and treatment of acromioclavicular dislocation with special reference to Tossy's grade III].

Seventy patients classified as Tossy's Grade III acromioclavicular dislocation were studied clinically and radiographically, and treated conservatively. Twenty acromioclavicular joints from 11 cadavers were dissected for a detailed anatomical evaluation of acromioclavicular joints. Anatomical findings showed that the conoid ligament played an important role for the fixation of the clavicular end to the acromion. Patients with dislocation classified as Tossy's Grade III were divided into two subtypes, A and B, according to the distance between the clavicle and acromion on the radiograph. Arthorography was performed on 22 patients. The arthograms were classified into three types, I, II and III, depending on the leak spread and flow of the contrast medium around the acromioclavicular joints. Types I and II arthorograms were seen in all cases classified as Type A on X-rays, most of the Type III arthorograms were seen in cases classified as Type B. Favorable results were obtained in eighty-six per cent of Type A cases. Fair to poor results, however, were achieved in 60% of type B cases. From the result of this study, the author concludes that Tossy's Grade III, complete dislocation, should be classified into two subtypes and surgical treatment should be considered for Type B or complete dislocation.