Os acromiale may be a contraindication of the clavicle hook plate: case reports and literature review

Background Os acromiale can be potentially missed or misdiagnosed as acromion fracture, and this can affect treatment determination if it is complicated with an ipsilateral shoulder injury. The clavicle hook plate is a widely used technique for distal clavicle injuries, leading to transacromial erosion, particularly when in the presence of os acromiale. Case presentation A 70-year-old man and a 78-year-old man who had limited mobility and severe pain in their right shoulders following falls attended the emergency center. Both patients were diagnosed with os acromiale with CT or MRI and acute distal clavicle fracture or acromioclavicular joint dislocation. Following a comprehensive evaluation, os acromiale may limit the application of a clavicle hook plate due to potential transacromial erosion. The distal clavicle fracture with ipsilateral os acromiale received treatment with a volar radius locking T plate, and the acromioclavicular joint dislocation with ipsilateral os acromiale was reconstructed using suture anchors. Both yielded satisfactory outcomes and voided transacromial erosion. Conclusions Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate. An axillary lateral radiograph is recommended to detect potential os acromiale in patients using a hook plate.

Os Acromiale in Reverse Total Shoulder Arthroplasty: A Cohort Study

Background: Increased passive deltoid tension after reverse total shoulder arthroplasty (RTSA) potentially leads to displacement or tilting of a preexisting os acromiale. Purpose: To analyze patients with an os acromiale who underwent RTSA and compare their outcomes and complications with a matched control group without an os acromiale. Study Design: Cohort study; Level of evidence, 3. Methods: In this study, 45 shoulders in 42 patients with an os acromiale (cases) were matched to 133 patients without os acromiale (controls) who underwent RTSA between 2005 and 2016. The mean follow-up was 52 ± 32 months. Matching criteria included sex, type of surgery, duration of follow-up, and age. The Constant score (CS), Subjective Shoulder Value (SSV), and radiological outcomes were assessed postoperatively at 1-year, 2-year, and final follow-up visits. Results: The mean CS, SSV, and range of motion improved from preoperative levels to the final follow-up in both groups ( P < .01). Patients with an os acromiale had a relative CS of 70 ± 23 versus 76 ± 21 points ( P = .15) and an SSV of 70 ± 30 versus 73 ± 24 ( P = .52) compared with controls at the final follow-up visit. Patients with an os acromiale had significantly decreased active flexion of 104° ± 33° versus 114° ± 33° ( P = .03) at 1 year and active abduction of 103° ± 37° versus 121° ± 38° at 2 years postoperatively ( P = .02). A postoperatively painful os acromiale was found in 12 cases (27%) and spontaneously resolved in 8 cases after a mean of 33 months (range, 12-47 months; P = .04). Conclusion: RTSA reliably restores patient satisfaction despite the presence of an os acromiale, with a slightly impaired range of motion. Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients, but this resolves spontaneously over time in the majority of patients.

Reverse shoulder arthroplasty with os acromiale

Function and strength of the deltoid muscle are important in reverse shoulder arthroplasty (RSA). Moreover, location and shape of the acromion, clavicle, and scapular spine, which are origins of the deltoid muscle, are also important. The frequency of os acromiale is 5% to 15%; however, it is rare in the Asian population, affecting approximately 0.7% of Koreans. RSA has rarely been reported in patients with os acromiale. We present a case series of two patients with cuff tear and arthropathy combined with os acromiale who underwent RSA. From 2016 to 2018, two patients with os acromiale who presented with pain and limited range of motion (ROM) underwent RSA with cuff tear arthropathy using the subscapularis-sparing deltopectoral approach. Their ROM, visual analog scale (VAS), and satisfaction were evaluated before and after surgery. In both patients, VAS decreased, ROM increased, and postoperative satisfaction increased. There were no specific complications due to os acromiale. The VAS, ROM, and satisfaction of patients improved after surgery compared with values before surgery. Thus, os acromiale is not a contraindication for RSA. However, careful attention must be given during surgery to ensure optimal repair and recovery.