There are four parts to the proximal humerus.
The proximal humerus is the part of the arm bone which forms the shoulder joint. In 1934, Codman described these parts: head, shaft, greater tuberosity and lesser tuberosity. The Neer classification system helps to guide treatment of these fractures. To qualify as a separate part, a piece must either be displaced 1 cm or be angulated 45 degrees from its normal position. Thus, there are two-part, three-part and four-part proximal humerus fractures. One-part fractures are essentially non-displaced fractures.
Most of these fractures are treated without surgery.
Most fractures will heal in either a sling or a shoulder immobilizer. If the fracture pattern is stable, early passive motion may be started within a few weeks. This is how long it takes for some provisional healing to take place. Once the fracture fragments start moving together as a unit, the arm should be moved to prevent a frozen shoulder. Passive motion is where somebody else, a physical therapist for example, moves your arm for you. Early on, it is inadvisable to do any "active" motion, where you would actively lift up your arm. This could cause the muscle forces to pull the fracture fragments apart before they are completely healed. Another example of passive motion is using a pulley system to use your other hand to lift up your broken shoulder. Alternatively, pendulum exercises, where the arm hangs down and you move your body around the arm, can be done.
Some of these fractures require surgery.
Usually, three- and four-part fractures should be treated surgically. The pull of the rotator cuff tendons on the tuberosity pieces cause them to displace and not heal. A plate and screws (internal fixation) can hold these pieces in the proper alignment as they are healing. Another advantage of internal fixation is to allow early range of motion exercises. Again, this can prevent a frozen shoulder.
Sometimes, the fracture cannot be fixed.
These cases include fractures which splits the humeral head, fractures compromising the blood supply of the humeral head, fractures in osteoporotic bone which will not hold screws and severe four-part fractures. In these circumstances, a shoulder replacement may be a better option. This involves placing a stem down the canal of the arm, with a metal cap to move against the shoulder blade.
Shoulder hemiarthoplasty usually results in a difficult recovery.
Because only the ball part of the shoulder is affected, only the ball side is replaced, leaving the shoulder blade untouched. This only replaces half of the joint and is therefore termed a hemiarthroplasty. When this is needed, it means that the fracture was pretty severe. Rarely do patients get their arm to above shoulder level following this surgery. The reason is the difficulty in getting the tuberosities to heal, and the rotator cuff tendons are attached to the tuberosities.