Arthroscopic decompression for impingement syndrome secondary to an unstable Os acromiale

Purpose: The purpose of this study was to examine cases of patients with im pingement syndrome secondary to an unfused, unstable, os acromiale. Type of Study: Retrospective case series; Materials and Methods: Twelve consecutiv e patients (13 shoulders) presented with impingement symptoms in the presen ce of an os acromiale. The os acromiale, at the meso-acromion level, was se en on standard radiographs. The patients were all treated conservatively wi th rotator cuff strengthening, stretching, anti-inflammatory medications, a nd steroid injections. All patients underwent an impingement test with lido caine, resulting in complete relief of their pain. After failure of the con servative management, the 12 patients (13 shoulders) underwent an extended arthroscopic subacromial decompression. The goal of the modified arthroscop ic acromioplasty was resection of adequate bone to remove the mobile anteri or acromial tip. In general, this consisted of more bony resection than the typical arthroscopic acromioplasty. Postoperatively, the patients began a rehabilitation program emphasizing early range of motion followed by isolat ed free-weight rotator cuff strengthening exercises. Five shoulders had a p artial-thickness tear of the rotator cuff. Four involved less than 50% of t he thickness of the rotator cuff. These 4 partial-thickness tears underwent arthroscopic rotator cuff debridement. One partial-thickness tear was grea ter than 50% and repair was performed with a mini-open deltoid-splitting te chnique. Results: Results were evaluated using UCLA shoulder scoring. Preop eratively, the score averaged 17, The 3-month postoperative score was 27, a nd at 6 and 12 months, averaged 28. The final follow-up score averaged 31. There were 11 satisfactory results with UCLA scores greater than or equal t o 28. Two unsatisfactory results showed UCLA scores in the fair category. F ull strength of the anterior deltoid and rotator cuff muscles was achieved in all patients by 6 months postoperatively as evaluated by manual muscle t esting. Twelve of the 13 shoulders were rated by the patients as having a s atisfactory result. All of the patients rated their cosmetic results as acc eptable. There was no evidence of postoperative deltoid detachment. No pati ent developed pain at the pseudarthrosis point. Conclusions: Given the prev iously reported poor results with attempts at fusion of an unstable os acro miale and open complete excision of meso-acromial fragments, the authors co nclude that an extended arthroscopic subacromial decompression results in a reasonable outcome for patients with impingement syndromes secondary to an unstable os acromiale.