This is a typical patient with osteoarthritis of the shoulder (glenohumeral arthritis). You can see that your proximal humerus and scapula make up your shoulder joint. So this is your humeral head, and this is the glenoid, or the socket because there should be space. Here in between the two, there should be about four millimeters of space. And you can see there’s really no space at all here. And this patient has kind of the typical big osteophyte. And you can see it down here. We call it the goat’s beard osteophyte, which is very characteristic of shoulder arthritis.
And we get multiple views here. This is one we call the axillary view. We’re looking at it basically from underneath the armpit up to the ceiling. And this, again, is the ball and socket or the humeral head and the glenoid. And the problem with shoulder arthritis is when you start developing advanced arthritis, the socket here starts to get worn. And it’s very difficult to assess this on plain X-rays, you know, we can get multiple X-rays, as you can see, and it still really doesn’t show us if there’s deformity of the socket. And then one of the most important things or factors in terms of really getting the best functional, lasting outcome is to correct the anatomy back to as normal as possible.
So that’s one of the reasons that we use CAT scans. And what we do is we get a high-resolution CAT scan. And it creates a three-dimensional reconstruction of the patient’s scapula, which you can see here.
So we can take the scapula and rotate it in space. However, we want to look at it. And this is what we use for surgical planning. So you can see this patient, which on the X-rays apparently did not really have a whole lot of glenoid wear or erosion. But what we’re looking at is this angle here. So what happens is this is the back of the shoulder. And this is the front. So, the ball sits right here. So the humeral head sits here. And what happens as shoulder arthritis progresses is that the ball starts to get pushed towards the back. And that’s what causes this glenoid or the socket side to wear down.
So this one, the numbers we look at, are over here on this left-hand side where it says patient’s anatomy. This talks about the glenoid inclination and glenoid retroversion. So this patient measures at 12 degrees. So if you measure an angle that goes with one plane is this direction and the second plane is this direction. So the glenoid socket is facing 12 degrees towards the back. The normal average is four degrees, so she’s three times what’s normal. So it’s very important to identify this because if we just went in and put a socket on and just laid it on the laid it on here like her socket is facing now, it would affect the function.
So we have tools for surgical planning like this, which is PreView Shoulder from Genesis Software Innovations (GSI). And we can actually move implants around. We can tilt it one way or another. You can see as we move, we can tilt front we can tilt backwards to try to replicate what normal anatomy is. And the goal here would be to try to get it to be this as measuring 12. We try to get as close to that four-degree version as possible.
So this is the Shoulder Innovations InSet™ Glenoid. Up here on the top left, where my cursor is, for choosing, we’re planning an anatomic shoulder which is the normal ball and socket, we can choose the size of the implant 22, 24, 27, and that’s the diameter. You can see they get bigger. The 22 is probably going to be the best for this patient because you want to have good bone all around it. And because she’s at 12 degrees, I would choose to use a five-degree correction. And what that means is if you’re looking at this implant profile, it is thicker on the back than the front. And by doing that, you’re correcting the face of the glenoid.
If I want to put this socket in and decide – again, what I’m doing here is exactly what I’m going to replicate it surgery. And if her socket, or the glenoid face, is 12 degrees, what I want to do is, I can put this in right here on the left, make the pocket right at 12 degrees. Now when I seat this down, I’m bringing out what I’m doing as I’m moving it down towards the bone. We want this to show full coverage. So this little red area shows that they are not seated fully.
So once I am seated fully, then I look at it, I make sure I’m centered, I’m in a good position. Usually try to favor a little bit superior, a little bit in the top of the of the socket. Now I want to make sure that I have a nice rim because basically, when we put these in, we’re creating, we’re creating a pocket. So you have a flat base that’s the same size as this is this disc. And then you also have a wall.
Because you create, you basically ream into the bone and create a little rim all the way around. And you want about a two-millimeter rim like It’s like down here on the bottom right. So if I go one more click or two more clicks, I can see I pretty much have a nice pocket all the way around. There’s one little area here where it’s not fully two millimeters. But what you want is you want at least 270 degrees of coverage, which we have here.
So this surgical planning software makes it very easy to plan. I know that I can go in and do this case, I don’t have to do any kind of off-axis reaming and reaming that’s not perfectly parallel to the to the surface. I can put a piece of put it right down against the surface. And I know when I correct it, it’ll end up like right here on the on the left in the middle at seven degrees, which is perfectly acceptable.
And so we can take this plan and go into the O R. There are no surprises. I know that I can put this five-degree implant in and get a correction and get an implant placed exactly where it needs to be to give this patient the best functional and long-lasting outcome.
And the important thing is that a lot of times, you just can’t see this deformity just by looking at these X-rays. So X-ray sometimes can really deceive you. So I get a CT scan on every patient even if it looks like everything is totally fine and normal and within normal limits, and I don’t think there’s any erosion. Many times you can get fooled on X-rays, and that’s why the CT scan is so important.
So this surgical planning software has been a game changer and provides basically a fully anatomic reconstruction that provides the best functional outcome, meaning improved range of motion strength, but also a lot, you know, much better lasting implant which will last the patient a lot longer.