Perpendicular plating achieves fixation of acromion fracture after RSA
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Open reduction and internal fixation of acromion fractures with or without previous reverse shoulder arthroplasty can provide significant relief for patients who lack mobility in the injured shoulder and have failed conservative treatment.
Special considerations when treating this injury include evaluation for osteoporosis, as well as for potential underlying inflammatory arthropathy, as these conditions are associated with these fractures after RSA. In some instances, patients have failed conservative management and present with a nonunion-type picture.
Source: Michael D. McKee, MD, FRCS
Patients who experience this fracture problem after RSA generally present with worsening pain and function after an initial postoperative improvement. This typically occurs within 6 months of their index procedure. If a patient presents with posterolateral pain and worsening function after RSA, advanced imaging with CT scanning, in addition to standard radiographs, is recommended to evaluate for acromial pathology (Figures 1, 2).
These fractures are challenging to treat given the anatomy of the acromion, as well as the underlying bone quality. The use of a single, superiorly placed plate has a high rate of failure due to the inferiorly directed shear forces of the deltoid (Figure 3). The authors have found the use of perpendicular, small fragment-type plates with multi-directional and multi-planar screw fixation to be a stronger, more effective construct. For fractures that are more lateral, the authors recommend plates with contoured hooks to help counteract the shear force of the deltoid (Figure 4).
Direct approach to scapular spine
The patient is positioned in the lateral position under general anesthesia with the head of the operating table tilted up approximately 20°. The operative arm is placed in a sterile stockinette and included in the field. A padded Mayo stand is used to hold the arm. Anatomic landmarks are drawn out, including the scapular spine, acromion and clavicle (Figure 5).
A direct posterosuperior incision is made over the scapular spine and is curved anteriorly over the acromion (Figure 6).
Fracture site exposure, preparation
Dissection is carried through the subcutaneous tissue until the deltoid muscle is identified. The fracture site is carefully palpated and the deltoid muscle is split longitudinally directly over the fracture site. For more lateral fractures (Levy types 1 and 2), this deltoid split is carried out distally over the acromion such that the lateral edge of the acromion is exposed and the underlying rotator cuff (often absent) and glenohumeral joint are visible. Sufficient exposure is carried out over the scapular spine proximally for posterior and superior small (3.5 mm) or mini (2.7 mm) fragment plates (Figure 7). The fracture site is mobilized, debrided and prepared with several 2-mm drill holes to facilitate bony healing (Video).
Surgical tip:
For injuries that present at more than 3 months, consideration should be taken to augment the mechanical repair with a biologic agent, such as autologous bone graft.
Fracture fixation and stabilization
The fracture is reduced and held provisionally with a 1.6-mm Kirschner wire. Depending on the orientation and location of the fracture, a lag screw may be placed along or through the scapular spine (Figure 8). A 2.7-mm mini-fragment plate is selected to allow at least three screw holes proximal and distal to the fracture. This is contoured to fit the curve of the acromion and scapular spine and it is fixed posteriorly along the spine. A second plate is selected to be placed perpendicular to the first plate, usually superiorly. The plate is then fixed to the scapula (Figure 9).
Surgical tips:
When placing the superior plate, take care to leave room for perpendicular screws through the posterior plate.
After assessment of bone quality, locking screws should be considered for use because bone quality is generally poor in this area, especially in the distal acromion.
For lateral fractures (Levy 1, 2)
The superior plate is contoured, and a plate-cutting device or large wire cutter is used to cut the plate through a plate hole, leaving a hooked edge (Figure 10). The plate is then placed superiorly with the hook capturing the lateral acromion and the remainder of the plate is flush along the scapular spine. Every effort is made to place a screw lateral-to-medial into the scapular spine with a hold directly along the lateral edge of the acromion.
The posterior plate is contoured around the posterior edge of the acromion and along the scapular spine with care taken to direct screws anteriorly.
Deltoid repair, wound closure
Prior to closure, the glenohumeral joint is evaluated for impingement-free range abduction. Radiographic confirmation is used to evaluate quality of reduction and ensure the subacromial space is maintained.
The deltoid muscle is carefully repaired along where it was split. Sutures may be passed through the plates or bone tunnels to augment the repair. The subcutaneous tissue and skin can be closed according to the preference of the operative surgeon.
The patient is placed in an abduction splint postoperatively. The patient will remain non-weight-bearing and be in the splint at all times for the first 2 weeks postoperatively. At 2 weeks, the patient can begin passive range of motion. At 4 to 6 weeks, the patient may gradually advance to activities of daily lifting and light weight-bearing activities. By 12 weeks, the patient should be allowed to return to full activities with no restrictions. Formal physical therapy can be ordered on a case-by-case basis based on individual patient progress.
- References:
- Galvin JW, et al. J Am Acad Orthop Surg. 2022;doi:10.5435/JAAOS-D-20-01205.
- Hill BW, et al. J Orthop Trauma. 2014;doi:10.1097/BOT.0000000000000040.
- Katthagen JC, et al. Arch Orthop Traum Surg. 2021;doi:10.1007/s00402-021-03879-z.
- For more information:
- Evan S. Lederman, MD is chief of sports medicine and professor, department of orthopedic surgery; Michael D. McKee, MD, FRCS, is chair and professor, department of orthopedic surgery; and Midhat Patel, MD, is an orthopedic surgery resident at department of orthopedic surgery, University of Arizona College of Medicine – Phoenix. They can be reached at 1320 N. 10th St., Suite A, Phoenix, AZ 85006. Lederman’s email: evan.lederman@bannerhealth.com. McKee’s email: michael.mckee@bannerhealth.com. Patel’s email: mpatel927@gmail.com.
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