Anatomy of the Humerus
The humerus is the bone of the upper arm which spans between the shoulder and elbow. The Head of the humerus forms to ball component of the shoulder joint. It articulates with the socket of the shoulder joint or glenoid. Nearby the head are 2 bony prominences. The larger one is the Greater Tuberosity. The other is the Lesser Tuberosity. The rotator cuff tendons are attached to the tuberosities. Just below the tuberosities the bone narrows a little to blend with the main shaft of the humerus. The zone between the head and the shaft of the humerus id referred to as the Neck of the humerus.
Causes of Proximal Humerus Fractures
Fractures of the upper or proximal humerus are common in elderly patients as a result of falls. Women with underlying osteoporosis are particularly prone to this injury. This type of fracture also occurs in younger patients but usually requires a greater degree of force, such as a fall from a height, bicycle, motorcycle and car accidents. Fractures of the humerus may also occur in combination with a dislocation of the shoulder
Types of Proximal Humerus Fractures
Fractures may involve any of these 4 main components of the proximal humerus or combinations thereof. Fractures may also occur in the main shaft of the upper humerus. The fractures can be classified on the basis of:
- The Number of Components of the humerus involved
- Degree of Displacement of fracture components
- Angulation of the bone fragments
- Interference to Blood Supply of the head of the humerus
Greater Tuberosity Fractures: This injury can occur as an isolated injury or in combination with a dislocation of the shoulder joint. Part of the rotator cuff is attached to the greater tuberosity of the humerus. If the bone fragment is displaced upwards and heals in that abnormal position it will interfere with free passage of the rotator cuff under the acromion.
Greater Tuberosity Fracture
Displaced Tuberosity Fracture
Lesser Tuberosity Fractures: This fracture is uncommon in isolation. It more often occurs in combination with fractures of other components of the upper humerus. If it heals in a displaced position there may be significant impairment of shoulder function.
Humeral Head Fractures: A fracture of the head of the humerus will involve will cause damage to the cartilage covering the ball component of the shoulder joint. It is a serious injury which often predisposes to arthritic wear of the shoulder joint in later life. Surgical restoration of the ball after a humeral head fracture is difficult. Sometimes the damage to the ball is sufficient to warrant replacement of the damage ball with a prosthesis.
Neck of Humerus Fractures: This type of fracture is also commonly referred to as a fracture of the Surgical Neck of the Humerus. A vast spectrum of fracture patterns can be observed. The better end of this injury spectrum would include un-displaced stable fractures which will heal well with conservative treatment and rehabilitation. At the other end of the scale the fracture may be grossly displaced. It may also be in combination with fractures of other components of the upper humerus. Some of these fractures may compromise the blood supply to the head of the humerus. The injury may be severe enough to need a prosthetic joint replacement.
Diagnosis of Proximal Humerus Fractures
- X-rays: They are the first line of investigation of humerus fractures. They will identify the initial fracture pattern. They will also be required to monitor the bone healing process in the weeks and months after the injury.
- CT Scan: This test is very help to evaluate comminuted (fragmented) fractures. 3D images of the humerus can be viewed from any desired direction. This will give a better understanding of more complex fractures and assist in planning a surgical stabilisation of the fracture.
Treatment of Proximal Humerus Fractures
Treatment options for proximal humeral fractures begin with pain relief, rest, x-ray monitoring, and graduated rehabilitation for simple un-displaced stable fractures. Displaced, unstable, or slow to heal fractures might require surgery to re-position the bone fragments and keep them stable during the healing process with pins, screws, or a metal plate.
Selection of the optimal treatment plan requires an analysis of factors such as:
- Fracture Patterns
- Degree of Displacement
- Bone Angulation
- Bone Quality
- Damage to the Joint Surface
- Interference with Blood Supply to the humeral head
- Associated Nerve or Tendon damage