These authors observe that the impact of scapula notching on reverse total shoulder arthroplasty (rTSA) clinical outcomes is controversial. They conducted an analysis of 324 rTSA patients with 5 years of minimum (average (75 mo) follow-up to evaluate the relationships between notching and clinical outcome.
47 patients (14.5%) had scapular notching; for these patients, the average notching grade was 1.7 0.8 (24 grade 1, 15 grade 2, and 8 grade 3). The average time to notch development was 51.4 months; grade 1, grade 2, and grade 3 notches developed at 49.0 months, 57.5 months, and 71.6 months, respectively. No preoperative differences were observed between cohorts.
At latest follow-up, scapular notching patients had significantly worse outcome scores and significantly less active abduction, forward flexion, and strength.
Comment: From these results it can be seen that patients with scapular notching do, on average, less well than those without.
Scapular notching is a phenomenon observed on x-rays as shown below. It can extend to the point where the screw fixation of the glenoid base plate is jeopardized.
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.
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.
Finally, scapular notching patients had significantly more complications, revisions, and humeral radiolucent lines.
Scapular notching is a phenomenon observed on x-rays as shown below. It can extend to the point where the screw fixation of the glenoid base plate is jeopardized.
What cannot be seen on x-ray is what is on the other side of the notching, i.e. the polyethylene of the humeral cup. The poly fares poorly when it repeatedly contacts the bone of the scapula. When the poly is eroded (see below) small particles of poly debris are released into the joint, where they can cause pain and stiffness. This particulate debris can also contribute to loosening of the humeral and glenoid components.
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.
To see a YouTube of our technique for a reverse total shoulder arthroplasty, click on this link.
=====
To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.
Use the "Search" box to the right to find other topics of interest to you.
You may be interested in some of our most visited web pages arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'
