Problems start to occur if the bone fails to heal and/or if there are several bone fragments that don't heal. The head of the humerus may start to collapse. The shape of the humeral head may also be distorted.

Any change in the position or alignment of the bone can affect the final result. Even if the shoulder joint is replaced, imbalance of the soft tissues may still present problems.

Studies show that the position of the greater tuberosity is especially important. This is an outcropping of bone that forms a bump where tendons and ligaments attach.

Any distortion of the humeral head can cause the greater tuberosity to move further back or away from the humeral head. The end result can be very unsatisfactory when pain and loss of motion lead to loss of function.

Judging the effects of a delay in surgery can be difficult. Malunion, failed fracture healing, and distortion of the anatomy are far more important and predictive of the final result. Given the two-month coma and recovery before surgery, your options may have been very limited at the time.