A recent multicenter study Predictors of acromial and scapular stress fracture after reverse shoulder arthroplasty: a study by the ASES Complications of RSA Multicenter Research Group found that these fractures occurred in one out of 25 cases of reverse total shoulder arthroplasty.
These fractures occur months or even years after the index reverse total shoulder. They may present with the subtle onset of pain over the acromion and spine and subtle radiographic findings.
or they may present as catastrophic loss of shoulder function with obvious x-ray changes.
The Levy classification of these fractures distinguishes the most serious (red) from the less serious (green), but all fracture types compromise the comfort and function of the shoulder.
Because they often occur in osteopenic bone, internal fixation of these fractures can be difficult and unrewarding for the patient.
Recently, the authors of Impact of Accumulating Risk Factors on the Acromial and Scapular Fracture Rate after Reverse Total Shoulder Arthroplasty with a Medialized Glenoid/Lateralized Humerus Onlay Prosthesis studied the compounding effect risk factors for acromial and scapular fractures in 9,079 patients having a medialized glenoid/lateralized humerus onlay rTSA prosthesis.
138 of 9,079 patients were radiographically identified to have a fracture of the acromion or scapula for a rate of 1.52%.
61% of the patients without fractures were female, whereas 80% of the patients with fractures were female
73.9% of these fractures occurred in the first year after surgery and 33.3% occurred within 3 months of surgery.
The most serious type of fracture (Type 3) were diagnosed a year and a half after surgery:
39.1% of the patients had a Type 1 fracture at an average of 9.1 ± 12.5 months after surgery,
39.1% of the patients had a Type 2 fracture at an average of 6.5 ± 12.1 months, and
21.7% of the patients had a Type 3 fracture at an average of 19.2 ± 20.9 months
Almost half of the patients in the fracture and non fracture groups had a preoperative diagnosis of osteoarthritis. The distribution of diagnoses was a bit different between the two groups.
Note that some of the patients were assigned multiple diagnoses, so the percents in the charts above add up to >100%.
Patients with the greatest fracture risk were females over 70 years of age with a diagnosis of rheumatoid arthritis.
Patients with these fractures had significantly worse self assessed shoulder comfortant and function (average Simple Shoulder Test = 6.4) in comparison to patients without fractures (SST = 9.2). Patients with Levy type 3 fractures had the worst outcomes (SST = 4.9) and had the least preoperative to postoperative improvement (change in SST = 1.8).
Comment: Whether they occur in one 1 of 25 or 1 out of 66 cases, fractures of the acromion and spine are a serious complication of reverse total shoulder arthroplasty with inferior clinical outcomes for the patient. This study looks at some of the factors that may affect the risk if these fractures. Other investigations have considered additional possible risk factors in addition to age, sex and diagnosis: bone density, prior acromioplasty, drill holes and screws in the base of the spine, excessive distalization of the tuberosity, contact between the acromion and the tuberosity, neck/shaft angle and the degree of lateralization/medialization of the glenosphere and humerus.
In this study patients with advanced age, female sex and the diagnosis of RA were at highest risk, yet less than 6% of the patients with fractures had these risk factors. What about the remaining 94%?
One strategy is to recognize that patients having anatomic arthroplasty are not at risk for these fractures. Almost half of the patients with fracture carried the diagnosis of osteoarthritis, which can usually be treated with an anatomic total shoulder - avoiding the risk of these fractures.
Therefore, the authors suggest that alternative treatments like anatomic total shoulder arthroplasty (aTSA) or hemiarthroplasty with or without use of a CTA humeral head may be alternative considerations for some of the patients receiving reverse total shoulder arthroplasty. To that point, the mean preoperative active elevation was >80 degrees for all the patients with standard deviations ≥40 degrees. Thus almost half of patients did not have pseudoparalysis and may have been well served by an anatomic or CTA hemiarthroplasty.
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
