Transacromial approach to obtain fusion of unstable os acromiale

The purpose of this study was to identify possible causes for the low union rate for surgically stabilized os acromiale. Between February 1990 and Nov ember 1995, fusion of an os acromiale was attempted in 15 shoulders in 12 p atients at our institution. All patients were men. The mean age was 54 year s (range 37 to 63 years). All shoulders had an os mesoacromiale considered too large for simple resection. An associated lesion of the rotator cuff ra nging from partial-to full-thickness tear was present in all patients. Elev en had an unfused acromial epiphysis in both shoulders. Two different surgi cal approaches were used. Seven shoulders were approached through an anteri or deltoid-off approach, thus potentially devascularizing the os acromiale. Eight shoulders were approached transacromially, preserving the deltoid or igin and hence the terminal branches of the thoracoacromial artery. The tec hnique of internal Fixation (tension band wiring) was the same for both gro ups. The mean follow-up was 44 months (range 13 to 72 months). Union, as de monstrated by axial radiographic views, occurred in 3 out OF 7 cases With a devascularized os acromiale and in 7 Out Of 8 shoulders with a perfused os acromiale (P = .017), respectively. Patients with a united os acromiale ha d a significantly better functional outcome as measured by the Constant sco re (P = .0169). In conclusion, aiming at a stable fusion of a sizable and h ypermobile os acromiale is probably desirable because it enhances the overa ll functional result. Obtaining consolidation was possible when the vascula rity of the acromial epiphysis was respected.