Displaced os acromiale fracture in the setting of a massive rotator cuff tear
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A 58-year-old woman was referred to our clinic for a massive, retracted right rotator cuff tear.
Her past medical history was complicated and included prior myocardial infarction, Crohn’s disease, hepatitis C, hypertension, depression, chronic obstructive pulmonary disease and smoking one pack of cigarettes daily for 30 years. Her referral was placed for rotator cuff pathology, but between this time and her initial visit (approximately 3 months), she sustained a minor trauma to the right shoulder during which she felt a “pop” while dressing. Subsequent imaging at her initial visit revealed a displaced os acromiale fracture (Figure 1). Prior to this minor trauma, an outside MRI was performed which confirmed her long-standing, massive rotator cuff tear, but also revealed the os acromiale in an anatomic position prior to her injury (Figure 2).
Source: Adam Seidl, MD
Clinical evaluation of the patient revealed pseudoparalysis of the right shoulder with diffuse tenderness throughout the joint. She was unable to tolerate passive range of motion and reported that her right arm was nonfunctional for activities of daily living. She was severely incapacitated by her condition and her acute deterioration was attributed to the interval displacement of her os. The patient had previously failed nonoperative treatment including physical therapy, NSAIDs and injections for her rotator cuff alone. Now that she is functionally debilitated, what are the surgical options?
What is the best next step in management of this patient?
See answer below.
Superior capsular reconstruction, open reduction and internal fixation
The surgical treatment for this patient consisted of an open superior capsular reconstruction (SCR), open reduction and internal fixation (ORIF) of the os acromiale and open suprapectoral biceps tenodesis concomitantly.
Operative technique
The patient was placed in the beach chair position under a general anesthetic with a preoperative interscalene nerve block. A strap incision was made just medial to the fracture site and a longitudinal split in the deltotrapezial fascia at the area of the Neviaser portal was made, thus exposing the fracture site. The fractured os acromiale was retracted laterally, the long head of the biceps tendon was tenotomized for lateral tenodesis, and the glenohumeral joint was entered through the visualized massive and retracted rotator cuff tear. The footprints on the greater tuberosity and on the superior glenoid bone were prepared by excising all remnant fibrous tissue. The suture anchors, which consisted of three 3.9-mm Knotless Corkscrew suture anchors (Arthrex) for the glenoid and two 4.75-mm SwiveLock anchor (Arthrex) in the tuberosity for the SCR, were then easily placed under direct visualization through the “booked” open acromial fracture (Figure 3). The sutures were sequentially passed through the dermal allograft and the allograft was shuttled into the joint, spanning from the superior glenoid to the superior greater tuberosity. A lateral row configuration was added to compress the lateral graft onto the greater tuberosity across the entire footprint (Figure 4). The intact subscapularis was sutured to the SCR graft, the long head of biceps was tenodesed using one of the tuberosity anchors and the deltotrapezial fascial rent was closed.
Scapular spine exposure
The scapular spine was then exposed through the same skin incision, and the acromial fracture site was further exposed. An abundance of fibrinous material was encountered in the fracture site, which was excised, creating a clean, bleeding bone edge on either side of the fracture. Reduction of the free fragment was performed by placing two #5 FiberWire sutures (Arthrex) into the deltoid-acromion bone-tendon junction. While holding the free fragment in an anatomic position, a precontoured acromial plate was placed superiorly on the acromion and fixated with a combination of locking screws in the free piece and non-locking screws medially (Acumed LLC). This superior plate was augmented with a 3.5-mm reconstruction plate (Stryker) placed perpendicular over the posterior and lateral acromion. The FiberWire sutures were tied around the superior plate to provide further repair reinforcement (Figure 5).
Allograft placement
An osteoinductive bone allograft material was placed at the fracture site. Intraoperative fluoroscopy verified anatomic reduction of the fracture and appropriate screw length and position (Figure 6). The wound was irrigated and closed appropriately. Postoperatively, the patient was placed on a delayed SCR protocol and was prohibited from active motion for 3 months. She was most recently seen at her 1-year postoperative visit and was doing well. Her fixation was intact and she had active forward elevation to 90° and active external rotation to 40°.
Discussion
Os acromiale is an anatomical variant that occurs in roughly 3.4% to 7% of individuals and results from a failure of ossific fusion of the acromion during development. It has been reported that individuals with os acromiale have a degree of inherent instability and may be at risk for degenerative changes or symptomatic pain at the os-scapula interface. Symptomatic cases have been described in the literature and treatments, including os excision, decompression and internal fixation, have all been reported to have varying success rates. Os excision is a reasonable alternative to internal fixation when the deltoid insertion may be preserved. However, in the setting of significant displacement, the deltoid’s insertion may become compromised.
This report describes a case of a severely displaced os acromiale fracture after a minor trauma in the setting of an underlying, irreparable, massive rotator cuff tear. The senior author’s decision to proceed with SCR and ORIF concomitantly was multifactorial. First, os excision alone was nonviable as a significant amount of the patient’s deltoid was attached to the displaced fragment. Second, ORIF alone was likely to place the patient at risk for fixation failure, as there are high mechanical stresses placed across the superior shoulder in the setting of a deficient rotator cuff. Lastly, SCR was felt to be relatively accessible given the interval available through her displaced os acromiale. It is worth noting that ORIF plus reverse shoulder arthroplasty was also considered, but again, this would place new mechanical stresses across the superior shoulder and may place her at risk for early fixation failure.
Unusual displaced os acromiale case
Os acromiale are a relatively common anatomical variant, but infrequently become pathologic. Here a unique case report is presented of a displaced os acromiale in the setting of a massive, irreparable rotator cuff tear. The opportune access to the subacromial space through the displaced fragment allowed for a simultaneous SCR along with internal fixation of the displaced fragment. The patient in this case had a good functional outcome at 1 year postoperatively with forward elevation to 90° and external rotation to 40°. While this case highlights a unique surgical problem in a single patient, the anatomical considerations are widespread and applicable to all pathologies of the shoulder.
- References:
- Barbier O, et al. Orthop Traumatol Surg Res. 2013;doi:10.1016/j.otsr.2012.10.020.
- Campbell PT, et al. Orthopedics. 2012;doi:10.3928/01477447-20121023-16.
- Peckett WRC, et al. J Shoulder Elbow Surg. 2004;doi:10.1016/S1058274604000400.
- Rovesta C, et al. Musculoskelet Surg. 2017;doi:10.1007/s12306-017-0463-2.
- Spiegl UJA, et al. J Shoulder Elb Surg. 2015;doi:10.1016/j.jse.2014.09.040.
- Yammine K. Clin Anat. 2014;doi:10.1002/ca.22343.
- For more information:
- Christopher Joyce, MD, can be reached at Colorado Orthopaedics, 10535 Park Meadows Blvd., #301, Lone Tree, CO 80124; email: christopher.joyce2@gmail.com.
- Steven D. Jones Jr., MD, and Adam Seidl, MD, can be reached at the University of Colorado, Department of Orthopaedic Surgery, 12631 E. 17th Ave., Mail Stop B202, Aurora, CO 80045. Jones’ email: steven.jonesjr@cuanschutz.edu. Seidl’s email: adam.seidl@cuanschutz.edu.
- Edited by Steven D. Jones Jr., MD, and Donald (DJ) Scholten, MD, PhD. Jones is a chief resident in the department of orthopedic surgery at the University of Colorado. He will pursue a fellowship in sports medicine at Stanford University following residency completion. Scholten is a chief resident in the department of orthopedic surgery at Wake Forest University School of Medicine in Winston-Salem, North Carolina. He will be a sports medicine fellow at the University of Michigan following residency. For information on submitting Orthopedics Today Grand Rounds cases, please email: orthopedics@healio.com.
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