Before having surgery, patients are told what can go wrong during or after the operation. The most common complication after shoulder joint replacement (arthroplasty) is shoulder instability. Instability means that the joint is unsteady and could even dislocate.
Knowing what causes this problem may help doctors prevent it. Shoulder instability may not have a single cause, as these researchers determined. They studied patients at the Mayo Clinic, each of whom had a second surgery to repair a failed shoulder arthroplasty.
After recording what they found wrong during the second operation and how they fixed it, the authors came to some conclusions. One-third of all patients had an accident or injury that appeared to cause a soft-tissue imbalance. Either a muscle had torn or the joint capsule was too loose or too tight.
Poor positioning of the joint implant is another common cause of failure. Sometimes, the wrong size implant is used. In other patients, too much bone is removed when putting the implant in place. Bone loss is directly linked to shoulder instability.
Some of the bad news can get worse. The second surgery for a failed shoulder replacement often fails, too. Researchers at the Mayo Clinic say that every effort must be made to prevent instability in the first operation.
Studying failed shoulder replacements is important in finding ways to prevent this from happening in other patients. For example, if too much bone is removed, a bone graft may be needed. The authors advise looking for more than one cause during the operation. Each problem that is encountered can then be repaired at the time of the first arthroplasty.