Scapular Notching After a Reverse Shoulder Replacement: What the X-Ray Finding Means and Whether It Matters

Scapular notching is a bony defect worn into the lower edge of the shoulder blade (the scapular neck) underneath a reverse shoulder replacement, caused by the plastic cup on the arm bone contacting the bone there as the arm comes down to the side; it is seen on X-ray in anywhere from about 10% to 96% of reverse replacements, and most of it is low grade.¹ It is something your surgeon reads off a follow-up X-ray rather than something you feel, which is exactly why the word on a clinic letter can be alarming out of context.

I met the phrase in a clinic letter about my own reverse replacement, a line under the X-ray report that said “early grade I inferior notching, stable.” Nobody had mentioned it before the operation and I spent an evening convinced the shoulder was being eaten away. It was not. This is the plain account of what notching is, why reverse replacements get it, how much it matters, and what your surgeon is watching for, checked line by line by a consultant shoulder surgeon. The design that makes notching possible is explained in reverse shoulder replacement.

What scapular notching is

Scapular notching is erosion of the bone at the bottom of the scapular neck, just below the socket component (the baseplate and its metal ball, the glenosphere) of a reverse shoulder replacement.¹ On an X-ray taken from the front it shows as a notch-shaped gap in the bone under the baseplate, which is where the name comes from.

Surgeons grade it on a 0 to IV scale, usually the Nerot and Sirveaux classification. Grade I is a small notch; the higher grades describe erosion that reaches and then passes the lowest screw, and grade IV extends under the baseplate itself. Exact wording varies a little between versions of the scale.² The grade describes how far the defect has travelled, and the higher grades are the ones that draw attention because they approach the parts that hold the socket component in place.

Why reverse replacements notch

Notching happens because a reverse replacement puts the plastic cup on the arm bone, and when the arm is brought down against the side, the rim of that cup can meet the lower edge of the scapular neck below the metal ball.³ Repeated contact, thousands of times a year in ordinary life, wears into the bone. Whether plastic wear particles from the contact add to the bone loss is still debated.²

This is a direct consequence of the design. The original reverse concept, developed by Paul Grammont, deliberately moved the centre of rotation of the shoulder inward (medialised it) to give the deltoid a longer lever arm and lift the arm without a rotator cuff.¹ That geometry is what makes a reverse work so well for cuff tear arthropathy; it also brings the humeral cup close to the bone below the glenoid. An anatomic total replacement does not have this arrangement, so notching is a reverse-specific finding. Why a reverse was chosen in the first place, and why the rotator cuff decides it, is in anatomic versus reverse shoulder replacement.

How common it is

Notching is one of the most frequently reported findings after a reverse replacement, with rates ranging from about 10% to 96% across studies, a spread that reflects different implant designs, surgical techniques, and lengths of follow-up.¹ Once present it can progress over the years, which is why the trend between X-rays matters.

The longest follow-up gives the most honest picture. A 2025 systematic review of reverse replacements followed for at least 10 years found low grade notching (grades I and II) in roughly 8% to 59% of shoulders, and grades III and IV in roughly 7% to 47%, depending on the study.⁴ The same review noted that function in some long-term series declines from around 6 to 8 years after surgery, and listed notching alongside ageing and implant loosening among the factors thought to contribute. Older series, mostly using the original medialised designs, sit at the high end of these ranges.

Does it affect how the shoulder works?

On average, yes, but modestly: a 2020 meta-analysis of 11 studies found that shoulders with notching scored a few points lower on standard function scores and had about 6 degrees less forward lift and about 9 degrees less abduction than shoulders without it.¹ Rotation outward was not measurably different. Those are averages across groups, not a forecast for one shoulder.

The effect also seems to take time to show. A prospective series of 60 reverse replacements found no significant link between notching and outcome scores between two and five years, but a measurable association with pain and range of motion at five years and beyond, and no link at all between notching and how stable people felt their shoulder was.² The honest reading is that notching is a slow, mostly silent process whose effect, where it has one, emerges over years rather than months. Many people with a notch on their X-ray have a shoulder that does everything they ask of it, and what movement to expect from a reverse in the first place is set out in range of motion after shoulder replacement.

Why surgeons keep watching it

Surgeons follow notching on serial X-rays because notching is thought to be a risk factor for later loosening of the socket component, and loosening is one of the recognised reasons a reverse replacement is revised.²⁴ It is the direction of travel that matters: a stable grade I notch on X-rays a year apart tells a very different story from one that has moved two grades.

That is the main practical meaning of notching for a patient. It is one of the reasons a reverse replacement is followed up with X-rays for years rather than signed off at the first anniversary, and one of the reasons it is worth keeping those appointments even when the shoulder feels fine. If the socket component did begin to loosen, the usual signs are new pain in a shoulder that had gone quiet, or a decline in what the arm can do, and the account of what revision involves is in revision shoulder replacement.

Can it be prevented?

Notching can be reduced, though not reliably eliminated, through how the socket component is positioned and which implant design is used.¹ Placing the baseplate low on the glenoid so the metal ball overhangs the lower edge of the scapular neck widens the arc in which the arm can move without impinging, and is associated with less notching and better function.

Implant design matters too. Newer designs that move the joint outward (lateralisation), either on the socket side or the humeral side, or that change the angle of the humeral component, aim to keep the cup clear of the scapular neck as the arm comes down.³ Each change carries trade-offs of its own, including different loads on the shoulder blade, so there is no single design that wins every comparison. Asking a surgeon which implant they use for reverses and how they position it is a reasonable pre-operative question, and it belongs with the others in questions to ask before shoulder replacement.

What to do if your report mentions notching

If a follow-up report mentions notching, ask your surgeon three things: the grade, whether it has changed since the last X-ray, and whether the socket component looks secure.⁵ Most of the time the answer is a low grade, stable notch in a well fixed implant, and the plan is simply to keep up the routine X-rays.

There is nothing to do at home about notching itself. No exercise, medicine, or restriction reverses it, and the usual advice for a reverse replacement (avoid repetitive heavy lifting and sudden impact) is the same with or without it. What does matter is reporting change: new pain in a shoulder that had settled, a loss of lift or strength, or a new clunk. Those are reasons for an earlier review whatever the last X-ray said.

My own notch was graded I at my first-year review and was still grade I two years later. The surgeon’s words were that it was “the most boring thing on the film,” which I have come to find reassuring. Whether yours is equally boring is a question for the surgeon who can compare your X-rays over time, and not for a page or a forum.