Iatrogenic instability of the acromioclavicular joint leads to ongoing impairment of shoulder function even following secondary surgical stabilization.

PURPOSE: Iatrogenic instability of the acromioclavicular joint (ACJ) following distal clavicle excision (DCE) represents an infrequent pathology. Revision surgery to restore ACJ stability and alleviate concomitant pain is challenging due to altered anatomic relationships. The purpose of this study was to evaluate the used salvage techniques and postoperative functional and radiological outcomes in retrospectively identify patients with a painful ACJ following DCE. We hypothesized that iatrogenic instability leads to ongoing impairment of shoulder function despite secondary surgical stabilization.
METHODS: 9 patients with a painful ACJ after DCE (6 men, 3 women, 43.3 ± 9.4 years) were followed up at a minimum of 36 months after revision surgery. Besides range of motion (ROM), strength and function were evaluated with validated evaluation tools including the Constant score and the DASH score (Disability of the Arm, Shoulder and Hand questionnaire), specific AC Score (SACS), Nottingham Clavicle Score (NCS), Taft score and Acromioclavicular Joint Instability Score (AJI). Additionally, postoperative X-rays were compared to the unaffected side, measuring the coracoclavicular (CC) and acromioclavicular (AC) distance.
RESULTS: At follow-up survey (55.8 ± 18.8 months) all patients but one demonstrated clinical ACJ stability after arthroscopically assisted anatomical ACJ reconstruction with an autologous hamstring graft. Reconstruction techniques were dependent on the direction of instability. The functional results demonstrated moderate shoulder and ACJ scores with a Constant Score of 77.3 ± 15.4, DASH-score of 51.2 ± 23.4, SACS 32.6 ± 23.8, NCS 77.8 ± 14.2, AJI 75 ± 14.7 points and Taft Score 7.6 ± 3.4 points. All patients stated they would undergo the revision surgery again. Mean postoperative CC-distance (8.3 ± 2.8 mm) did not differ significantly from the contralateral side (8.5 ± 1.6 mm) (p > 0,05). However, the mean AC distance was significantly greater with 16.5 ± 5.8 mm compared to the contralateral side (3.5 ± 1.9 mm) (p = 0.012).
CONCLUSION: Symptomatic iatrogenic ACJ instability following DCE is rare. Arthroscopically assisted revision surgery with an autologous hamstring graft improved ACJ stability in eight out of nine cases (88.9%). However, the functional scores showed ongoing impairment of shoulder function and a relatively high overall complication rate (33.3%). Therefore, this study underlines the importance of precise preoperative indication and planning and, especially, the preservation of ACJ stability when performing AC joint resection procedures. LEVEL OF EVIDENCE: Case series, LEVEL IV.