Sunday, August 7, 2011

Revision surgery for failed shoulder replacement arthroplasty due to humeral fracture - our approach, Part 8

Fracture of the humeral shaft is a recognized cause of shoulder arthroplasty failure. The risk for such a fracture is increased in individuals with poor bone quality or with an increased risk of falling because of poor eyesight, balance problems, confusion, or muscle weakness. The risk is also increased when there has been weakening of the humeral shaft from reaming, as explained in a previous post, or from loosening of the humeral component. Our experience indicates that humeral fracture risk is lessened when endosteal reaming is minimized and when impaction autografting is used to secure the stem in the humeral shaft.

The diagnosis of shaft fracture is revealed by high quality anteroposterior and lateral views that span the entire humerus.  

If the component is not loose, it can be difficult to remove in the presence of a fracture. In this situation, we prefer to leave the prosthesis in place and fix the fracture using a plate placed so that the screws in the proximal fragment pass through the cortical bone either anterior or posterior to the stem of the prosthesis. 

If good fixation in the proximal fragment cannot be achieved with screws, circlage around the plate may be used, but extreme care must be used to avoid circlaging the radial nerve posteriorly and to avoid crushing the bone with excessive tightening of the wires.

If the humeral prosthesis is loose, it may be removed and replaced with a long stem prosthesis fixed with cement or bone graft and supplemented with circlage fixation, again taking care to protect the radial nerve.

In all cases of humeral fracture, we prefer to us autogenous bone graft or cancellous allograft around the fracture site.