These authors reported on clinical and radiographic outcomes of nonoperative treatment of acromial and scapular spine fractures (ASF) after reverse total shoulder arthroplasty.
44 patients diagnosed with ASF following RSA were matched 1:3 to a control group based upon gender, age, and preoperative function.
ASF were identified at a median of 2 months and were followed for a median of 37 months. All ASF patients were treated nonoperatively.
Overall, patients with ASF had inferior clinical outcomes with a higher rate of dissatisfaction when compared to controls.
Lateral fracture subtypes (I and IIA) were similar to controls and had little impact on outcomes.
Medial fracture subtypes (Type-IIB, IIC, and III) demonstrated inferior outcomes when compared to controls, with Type-III fracture patients demonstrating no improvement from baseline.
The overall non-union rate was 61.4%, with high rates of scapular rotation and osteolysis in medial fracture subtypes. Nonunion was associated with a higher incidence of secondary radiographic findings, including scapular rotation, progressive notching, and osteolysis.
The authors concluded that fractures which occur at or medial to the glenoid face demonstrated high rates of unsatisfactory results and worse clinical outcomes as well as increased rates of scapular tilt, progressive scapular notching and osteolysis
Comment: For good reason, there has been substantial interest in the prevention, diagnosis and treatment of acromial and spine fractures after reverse total shoulder arthroplasty. It seems that the symptoms from these fractures are related both to the location of the fracture and the amount of displacement.
Here's a case: a middle aged man had a reverse total shoulder after multiple failed cuff repairs of the left shoulder. At the six week checkup, all was well clinically and radiographically.
He started gentle assisted flexion exercises. Two days after the office visit while reaching up he had sudden pain in the shoulder and heard a 'crack'. He returned to the office at which time tenderness was noted at the posterior acromion. The AP view was not remarkable.
This case reveals the potential of fracture of an acromion that is not used to being loaded.
Here's another case:
An 85 year old lady presented with severe cuff tear arthropathy as shown below.
She had a reverse total shoulder in early 2012. Two years after surgery she had excellent comfort and function. An axillary x-ray at that point is shown below.
Research is ongoing to determine the effect of prosthesis type and position that influence the risk of these fractures.
However, the type of patient at greatest risk is becoming clearer:
These authors investigated the incidence of acromial stress fractures (ASFs) after reverse total shoulder and and sought to identify preoperative patient characteristics associated with their occurrence.
They identified 1479 patients undergoing either primary or revision RTSA between 2013 and 2018 with minimum 3-month follow-up. ASFs were defined as radiographic evidence of an acromial or scapular spine fracture with clinical symptoms (eg, tenderness over the acromion or scapular spine).
Overall, 54 (3.7%) patients were diagnosed with an ASF after RTSA. Patient-related factors independently associated with the development of an ASF included female sex, rheumatoid arthritis, osteoporosis, a diagnosis of degenerative joint disease with rotator cuff tear, and fracture malunion/nonunion (OR, 5.21; 95% CI, 1.20-22.76; P < .05).
This is an interesting study, although the followup time is short. Many acromial fractures occur more than 3 months after surgery.
The article below dives a bit deeper into the local changes in scapular bone density associated with age and sex.
Changes in Scapular Bone Density Vary by Region and are Associated with Age and Sex
They studied 97 three-dimensional models of the scapula that were segmented from routine clinical computed tomography (CT) scans, and obtained detailed calibrated bone density measurements for each bone model. The effects of age and sex on cortical and trabecular bone density were assessed for the entire scapula.
They found that cortical bone loss averaged to 1.0 mg/cc and 0.3 mg/cc per year.
Trabecular bone loss was 1.6 mg/cc and 1.2 mg/cc for female and males respectively.
Areas that were significantly affected by age included the acromion, the scapular spine, the base of the coracoid, the inferior glenoid neck as well as the glenoid vault.
Areas that were significantly affected by sex were the scapular spine and body. These findings are consistent with the risk factors for acromial and scapular spine fractures after reverse total shoulder.
Here are some other links relating to acromial and scapular spine fractures after reverse total shoulder: link 1, link 2, link 3, link 4, link 5 and this link.
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Here are some videos that are of shoulder interest
