Fracture of the surgical neck of the humerus occurs most often in elderly women. The fracture is usually caused by a fall on the shoulder. In the majority of cases, these fractures are impacted; sometimes they are widely displaced. The possibility of this fracture of the surgical neck of the humerus should be kept in mind in all elderly persons complaining of pain in the shoulder following a fall. Often the symptoms are minimal.
|FRACTURE OF NECK OF THE HUMERUS
Fracture of the surgical neck of the humerus is important to properly evaluate these fractures by AP and axial X-rays. Neer has classified these fractures into 4 types depending upon the construction of the fracture. He identified 4 parts in the upper end of the humerus – shaft, head, greater tuberosity and lesser tuberosity. Depending upon in how many parts the bone has fractured, he divided them into one to four part fracture. For example, a fracture where the head, the greater tuberosity, the lesser tuberosity and the shaft, all have separated, it will be called a four-part fracture. This classification helps in deciding the treatment and prognosis
In elderly persons, even with moderate displacements, it is generally adequate to immobilise the affected shoulder in a triangular sling. As soon as the pain subsides, shoulder mobilisation is started. In younger persons, if the fragments are widely displaced, they are reduced by manipulation under anaesthesia. Once reduced, the fracture can be stabilised by multiple K-wires passed percutaneously under image intensifier control. Often, open reduction and internal fixation may be required. A number of internal fixation devices have been in use; from simple K-wires to modern LCP based special plates. In badly comminuted fractures in an elderly, replacement arthroplasty is desirable. Axillary nerve palsy and shoulder stiffness are common complications.
FRACTURE OF THE GREATER TUBEROSITY OF THE HUMERUS
Fracture of the greater tuberosity of the humerus occurs in adults. The fracture is usually caused by a fall on the shoulder, and is undisplaced and comminuted. Sometimes, it is widely separated due to the pull by the muscle (supraspinatus) attached to it.
For minimally displaced, comminuted fractures, rest in a triangular sling is enough. The shoulder is mobilised as soon as the pain subsides. For displaced fractures, reduction is achieved by either holding the shoulder abducted in a plaster cast, or by open reduction and internal fixation. Painful arc syndrome (see page 304) and shoulder stiffness are the usual complications.
FRACTURE OF THE SHAFT OF THE HUMERUS
This is a common fracture in patients at any age. It is usually sustained from an indirect twisting or bending force – as may be sustained in a fall on out-stretched hand or by a direct injury to the arm.
|FRACTURE OF THE SHAFT OF THE HUMERUS
A humerus fracture can be considered a prototype fracture because it occurs in all patterns (transverse, oblique, spiral, comminuted, segmental etc.), may be closed or open, and may be traumatic or pathological.
Displacements are variable. It may be an undisplaced fracture, or there may be marked angulation or overlapping of fragments. Lateral angulation is common because of the abduction of the proximal fragment by the deltoid muscle. This angulation is further increased by the tendency of the patient to keep the limb by the side of his chest, resulting in adduction of the distal fragment. Often, distraction occurs at the fracture due to gravity.
Diagnosis is simple because the patient presents with the classic signs and symptoms of a fracture. There may be wrist drop, if the radial nerve is injured. An X-ray of the whole arm including the shoulder and elbow should be done.
Most of these fractures unite easily. Anatomical reduction is not necessary as long as the fracture is stable. Some amount of displacement and angulation is acceptable. This is due to the following reasons: (i) limitation of motion because of a moderate malunion in angulation or rotation goes unnoticed because of the multi-axial shoulder joint proximally; (ii) some amount of shortening goes undetected in the upper limb (unlike in the lower limb where shortening produces a limp); and (iii) the bone is covered with thick muscles so that a malunited fracture is not noticeable (unlike the tibia where malunion is easily noticeable). Strict immobilisation is not necessary. The aim of treatment is pain relief and prevention of lateral angulation and distraction. It is possible to achieve this by conservative means in most cases.
The following conser vative methods are useful in most cases:
a) U-slab: This is a plaster slab extending from the base of the neck, over the shoulder onto the lateral aspect of the arm; under the elbow to the medial side of the arm. It should be moulded on the lateral side of the arm in order to prevent lateral angulation. The U-slab is supported with a triangular sling. Once the fracture unites, the slab is removed (approximately 6-8 weeks) and shoulder exercises started.
b) Hanging cast: It is used in some cases of lower-third fractures of the humerus. The weight of the limb and the cast is supposed to provide necessary traction to keep the fracture aligned.
c) Chest-arm bandage: The arm is strapped to the chest. This much immobilisation is sufficient for fracture of the humerus in children less than five years of age.
In adults, early mobilisation of the limb can be begun by using a cast-brace once the fracture becomes sticky.
In cases where a reduction is not possible by closed manipulation or if the fracture is very unstable, open reduction and internal fixation is required. Most fractures can be fixed well with plate and screws. Intra medullary nailing is another method of internal fixation. Contaminated open or infected fractures are stabilised by using an external fixator.
1. Nerve injury: The radial nerve is commonly injured in a fracture of the humeral shaft. The injury to the nerve is generally a neurapraxia only. It may be sustained at the time of fracture, during manipulation of the fracture or while the fracture is healing (nerve entrapment in the callus). A special type of humerus fracture, where there is a spiral fracture at the junction of the middle and distal third, is commonly known to be associated with a radial nerve palsy. This is called Holstein Lewis fracture. The radial nerve injury results in paralysis of the wrist, finger and thumb extensors (wrist drop), brachioradialis and the supinator. There is a sensory change in a small area on the radial side of the back of the hand.
For cases reporting early, treatment depends on the expected type of nerve injury. In most closed fractures, the nerve recovers spontaneously. In open fractures, exploration is usually required. In neglected cases or when repair of a divided nerve is impractical, tendon transfers are needed. Modified Jone’s transfer is most popular. Here the muscles of the forearm, supplied by median and ulnar nerves, are used for substituting wrist extension, finger extension and thumb abduction-extension. The following tendons are used:
• Pronator teres→ Ext. carpi radialis brevis
• Flex. carpi ulnaris → Ext. digitorum
• Palmaris longus → Ext. pollicis longus
2. Delayed and non-union: Fractures
of the shaft of the humerus, especially transverse fracture of the midshaft, often go into delayed or non-union. The causes of non-union are: inadequate immobilisation or distraction at the fracture site because of the gravity.
Open reduction, internal fixation with a plate, and bone grafting is usually performed. In cases where the quality of bone is poor, an intramedullary fibular graft may be used to enhance the fixation. The limb is suitably immobilised using a U-slab or a shoulder spica.