Failed Shoulder Replacement: All is Not LostWith any new surgical procedure developed, there can be problems. In this case, we are talking about shoulder replacement surgery that fails due to fracture or bone loss. Treatment options are limited. Surgeons are looking for ways to change that.
In this study, surgeons from the Florida Orthopaedic Institute (Tampa) report on an expanded study they started several years ago. Patients in the first study (90 adults) received a reverse shoulder prosthesis. Twenty-five (25) of those patients were in this current study.
A reverse shoulder implant places a glenosphere (round ball component) where the shoulder socket used to be and a cup-shaped implant at the top of the humerus (upper arm bone). In the first study, this type of implant was used because the patients had a traditional shoulder replacement that failed. The pain and dysfunction were too great to just leave the original implant in place.
The 25 patients in the second study had additional problems to be solved. They had the reverse shoulder procedure as described, but ended up with bone loss at the top of the humerus. Major bone loss occurs when the first implant is removed. This in turn caused shoulder instability from deficiency of the rotator cuff (muscles that hold the shoulder in place). They had all tried conservative (nonoperative) care, but it didn't help.
So, the surgeons used a special allograft (bone graft donated from a bone bank) attached with cables to the proximal (upper area of the) humerus. That sounds simple enough. But the procedure requires the surgeon to measure how much bone loss is present in order to determine the size and shape of the bone graft needed. And just the right amount of tension must be created using the bone graft to restore correct orientation of the prosthesis stem inside the humerus.
The patients all had a deficient rotator cuff because of the bone loss. When bone loss extends past where the muscles normally attach, the muscles become weak and cannot contract normally. That complicates matters because without the muscles to provide tension, the biomechanics of the shoulder are altered and shoulder instability becomes a problem. The allograft helps because it can be placed in such a way as to also improve tension from the deltoid muscle in the upper arm. The result is a stable shoulder once again.
The authors provide X-rays and photos to help guide the surgeon in understanding the procedure. Special X-ray views (e.g., Y lateral, rotation Grashey films) were used to see how much bone loss was present and to look for loosening of the implant stem inside the humerus. Subluxation (partial dislocation) of the humeral head was graded from zero (no subluxation) to three (more than 50 per cent subluxed).
Results of this restorative revision surgery were measured using X-rays, patient report of pain, shoulder range-of-motion, and function. Final X-rays taken in the study were used to look for subluxation, broken hardware, or loosening of any of the component parts.
They were also able to assess how well the graft had been incorporated using the same follow-up X-rays. They could tell the graft had taken or become one with the host bone when the junction line between the host and the graft was no longer visible. Loss of graft bone (called resorption) could be measured by comparing X-rays taken right after surgery (with the implant newly installed) with X-rays taken later during the follow-up period.
The procedure was successful for three-fourths of the group. They were satisfied with the results and rated their improved motion and function as good-to-excellent. Videos and range-of-motion measurements taken of the patients before and after the revision surgery confirmed the patients' reports of improvements.
The remaining patients had complications such as infection, dislocation, fracture, and instability. Some could be treated conservatively, while others required another revision surgery. Each patient was treated individually according to the problem present and with the best treatment option available at the time.
The authors conclude that when a reverse shoulder procedure is done after a failed shoulder replacement and bone loss results, all is not lost. The allograft-prosthesis approach described in this study can save the joint, reduce pain, and preserve function. This type of shoulder reconstruction requires considerable experience on the part of the orthopedic surgeon.
Although the results of this study show promise for this salvage technique, it remains to be seen how it holds up in the long-run. The patients will be followed and long-term results reported sometime later.
Ariel Chacon, MD, et al. Revision Arthroplasty with Use of a Reverse Shoulder Prosthesis-Allograft Composite. In The Journal of Bone & Joint Surgery. January 2009. Vol. 91A. No. 1. Pp. 119-127.
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