While reverse total shoulder is becoming an increasingly popular procedure, we regularly see patients presenting to our clinic because of clinical failure. Here are two examples from this morning. Both of these patients had substantially less shoulder function after their reverse total shoulder than before it was performed.
First a reverse with an augmented baseplate that has been painful and dysfunctional since the reverse arthroplasty. While the cause of the pain and functional loss has not yet been established, there is concern about the incomplete seating of the baseplate on the bone of the glenoid.
A CT scan confirmed the lack of seating of the baseplate along with an acromial fatigue fracture
Second is a patient whose shoulder was relatively functional both before and after a reverse until the sudden atraumatic onset of an acromial fracture. While the fracture itself is no longer symptomatic the displacement of the acromion has rendered the shoulder pseudoparalytic, probably due to loss of tension in the deltoid.
In addition to the inability to use the arm away from the side, the shoulder joint area is becoming increasing painful at rest. Note the high degree of scapular notching which raises the possibility of reaction to polyethylene particles resulting from contact of the humeral liner with the scapular bone and screw
A bit more about notching
Anytime we have unintended contact between high density polyethylene and bone, it is a problem. Scapular notching is a radiographic finding, but the real concerns are about (1) the damage to the poly of the humeral cup, (2) loss of the bone of the scapula that supports the glenoid component, and (3) the potential for instability resulting from leverage of one against the other. See this previous post which discusses this phenomenon in some detail.
In the Grammont-type reverse total shoulder, contact of the adducted humeral component against the scapula is not uncommon as shown in this figure from a manufacturer's website.
These authors retrospectively reviewed 448 patients who underwent a Grammont-type reverse total shoulder (461 shoulders) performed for rotator cuff tear arthropathy or osteoarthritis with cuff deficiency with a mean followup of 51 months (range, 24-206 months). They found notching of the scapula in 68% of the cases; it was present in 48% at one year after surgery.
Notching was more common in active patients, in patients with cuff tear arthropathy, and in patients with greater degrees of superior displacement of the humeral head before surgery. Strength and range of motion were compromised in patients with notching.
Importantly, 36% of shoulders with notching had humeral radiolucent lines (in contrast to 17% in those without notching), suggesting the possibility that polyethylene particles from the humeral cup causing bone resorption. Similarly glenoid loosening was three times more common in the presence of notching.
The authors point out that standardized plain x-rays are necessary for the evaluation of notching, noting that sometimes notching is better seen on the axillary view.
Comment: Scapular notching is important and can be expected to adversely affect the long term durability and function of the reverse. It is best avoided by (1) use of a glenoid component design that offsets the center of rotation from the scapula, (2) proper positioning of the glenoid component at the inferior aspect of the glenoid, (3) avoiding superior tilt of the glenoid component, and carefully checking for contact between the humeral component and scapula at surgery when the arm is adducted and rotated. If contact is noted after component implantation, careful resection of the contacting scapular bone may be helpful.
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link)
The smooth and move for irreparable cuff tears (see this link)
The total shoulder arthroplasty (see this link).
The ream and run technique is shown in this link.
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
