Anteroposterior instability of the distal clavicle after distal clavicle resection.

Resection of the lateral end of the clavicle disrupts the acromioclavicular articulation and creates the potential for abnormal postoperative motion. Seventeen isolated distal clavicle resections were reviewed to assess translation of the acromioclavicular articulation in the anteroposterior plane and its relationship to patient outcome. Stress radiographs were used to quantitate the translation of the distal clavicle and the amount of bone resected. Radiographs of the contralateral shoulder served as a control. Patients completed a questionnaire on shoulder function and pain and were examined preoperatively and postoperatively. The total translation (anterior plus posterior) in the anteroposterior plane averaged 8.7 mm (range, 3-21 mm) for surgically treated shoulders and was significantly greater than that for the contralateral shoulders (mean, 3.2 mm; range, 1-6 mm). Patients' postoperative visual analog pain scales correlated with the magnitude of anteroposterior translation. The amount of translation and the postoperative pain scores did not correlate with the apparent joint space seen on radiographs after surgery. The correlation of pain scores with the amount of translation shows that excessive anteroposterior instability of the distal clavicle can cause postoperative shoulder pain and poor surgical outcome.