The effects of hook plates to the subacromial space - A clinical and MRT study

Aim: The analysis of middle- and long-term results after treatment of acromioclavicular joint injuries with a hook plate as a temporary implant and a comparison of the results with those described in literature have been made. Method: In a retrospective study we were able to conduct follow-up examinations on 28 out of 39 Tossy III patients (72%) who received surgical treatment using a hook plate according to Dreithaler. Examinations took place on average 3.0 (1.2-5.6) years after surgery. A special focus of attention was the effect of the hook plate on the subacromial space. Accordingly, physical examination was supplemented by sonography of the shoulder as well as comparative bilateral shoulder MRI. Results: 86% of our patients expressed satisfaction with the functional outcome of surgery as opposed to 54% concerning its cosmetic result. In shoulder sonography no patient turned out to have suffered a higher grade rotator cuff lesion, whereas age-related degenerative alterations were found in 46% of the patients. Instability under load was found in 7 patients (25%). Among these were 3 with severe instability (11%). 2 patients (7%) were found to have a permanent subluxation of the acromioclavicular joint with partial range of motion impairment. All scores monitored (DASH, Taft, Constant-Murley) on average returned good to excellent results. MRI scans displayed no case of higher grade rotator cuff lesion. In accordance with the findings of ultrasound imaging a higher incidence of extraarticular ossification was found as well as, in some cases, arthrosis of the acromioclavicular joint. Conclusion: In our opinion, the hook plate designed by Dreithaler is easy to handle and serves as a qualified implant for temporary stabilisation of the acromioclavicular joint with middle- and long-term good to excellent results.