Two years ago, I got a shoulder replacement. It's been working great and I am totally pleased. But according to the X-rays, the socket side is loose. What does this look like on X-rays? How do they know for sure that's what's happening?
Radiologists examining X-rays for any signs of implant loosening look are radiolucency around the implant. Radiolucency describes a greater transparency than should be seen. In other words, the X-rays pass through the area because of a space between the bone and the implant.
They also use a scoring system that takes into consideration the radiolucent lines, position of those lines, thickness of the lines, and tilt of the implant. Each of those factors is given points. The more points that add up, the greater likelihood of implant loosening. So for example, someone with up to six points would NOT be considered "at risk" for implant loosening. A patient with a score of seven to 12 points IS at risk. And someone with more than 12 points using this scoring system has implant loosening.
X-rays taken right after surgery can be compared with your follow-up X-rays to look for any obvious changes from then to now. Lines drawn around the implant and through various parts of the shoulder can show shifts in the implant position that might indicate subsidence (implant sinks down into the bone).
And they also look for something called cranial migration of the humerus (upper arm). This refers to a gradual change in the position of the humerus upwards toward the top of the shoulder socket. Cranial migration can be classified as mild, moderate, or severe based on how far up the humerus had moved. The problem develops as a result of rotator cuff failure that cannot be corrected surgically.
The fact that you are not experiencing any pain, loss of motion, or change in function is fairly typical. In many cases, loosening is only seen on X-rays and does not appear to hamper the patient in any way. Of course, your surgeon will continue to follow you closely so you will want to be sure and go to all of your follow-up appointments.
Patric Raiss, MD, et al. Results of Cemented Total Shoulder Replacement with a Minimum Follow-Up of Ten Years. In The Journal of Bone and Joint Surgery. December 5, 2013. Vol. 94A. No. 23. Pp. e171(1)-e171(10).
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