Four to five per cent of all reported fractures are upper arm bone (humerus) fractures, most frequently occurring in the elderly population from falls. If the fracture is “non-displaced,” or the bone is still aligned after the break, the bone is simply immobilized for a period of healing time. If the bone is “mal-aligned” or no longer lining up to the point that it can heal itself, then a decision must be made whether to have a surgical correction or to allow the bone to remain the way it is. A mal-aligned humeral head (the ball part of shoulder joint) poses difficulty for surgical correction because of the numerous angles that must be accounted for at the shoulder joint, all of the muscles that attach and function surrounding it, and because an offset humeral head can pinch structures like nerves and blood vessels traveling by it during arm movements.
Elderly people who are not high functioning and do not have pain can do ok with malunions without corrective surgery. Broadly speaking, higher functioning individuals and the younger population have two surgical choices: to either preserve the joint (keep the humeral head) or to have a shoulder replacement (take off the humeral head and replace it with metal). This decision is made depending on the individual and type of mal-union present. The surgical goal is to improve a person’s quality of life and restore as much function as possible, but not necessarily return the person to their previous state of function as this often proves too surgically difficult.
Joint preservation is appropriate when there are two adjacent surfaces on the bone that can be put back together with hardware and there still is good blood supply to the humeral head. It is often challenging to determine what specifically is causing the pain at the site of the mal-union– the poorly healed bone itself, soft tissue (like tendons or muscles), or a boney protuberance. All of the contributing factors need to be addressed for good outcomes and joint preservation techniques address these.
Joint replacement is appropriate when there is a good chance of humeral head bone death due to a poor blood supply. Shoulder joint replacements remain complex even for the most skilled surgeons and the jury is still out on what type of shoulder replacement is most appropriate. The three main options are a partial humeral head replacement, a total humeral head replacement with normal anatomical alignment, or a total humeral head replacement with a reverse alignment from anatomical placement.