Lower Limb Injury

Hip fractures

It is the characteristic of osteoporotic fractures to occur at the ends of the long bones. Fractures of the femur are no exception to this and it is found that it is the elderly people tend to break their hips. The fractures in this region fall into one of two types. There are those fractures which pass through the neck of the femur and those fractures which affect the areas around the trochanters of the femur.

Whatever the nature of the fracture of the hip, many elderly people find it difficult to mobilise afterwards, and some find walking so difficult that it is necessary for them to enter an institution for their continuing care. This loss of independence can be very upsetting for many. It is for this reason that all encouragement and assistance need be given those who have sustained this type of injury  

It is with this idea, that the elderly person should keep the use of his (or her) legs and maintain their mobility, that most fractures of the hip are treated surgically. Fractures in osteoporotic bone, however, brings their own specific problems. The bone is generally weak. It does not hold the internal fixation devices very well and there is a chance that the surgical implants can ‘cut out’.

The configuration of the two fractures in the region of the hip are different and, accordingly, a different approach is used for each type of fracture.

 

Fractures of the femoral neck

Ideally one tries to preserve as much of the individual’s own bone as possible. However, a fracture of the femoral neck can affect the blood supply to the bone if it is displaced. For this reason one of two different techniques of surgical fixation are used.

If the fracture is not greatly displaced it is usually sufficient to fixate the fracture using a number of pins placed into the femoral head. If, however, the displacement of the fracture fragments is too great it is safer to insert some form of prosthesis. In the latter case the hip is exposed and the injured femoral head removed. The upper portion of the femur is fashioned to take the prosthesis which will replace this it. The appropriate prosthesis is inserted and the wound closed.

Both techniques, unfortunately, can have their complications. A small number of fractures fixed with pins will not heal and may collapse. Alternatively, those treated with a prosthesis run a small risk of the prosthesis dislocating.

 

Intertrochanteric femoral fractures

At the base of the femoral neck there are two bony protuberances, the greater and the lesser trochanters. It is common in the elderly person for the femur to fracture in relation to these trochanters. While there may be varying degrees of displacement, the surgical treatment of these types of fractures is slightly easier; all of them are treated using a combination pin and plate implant.

The fracture of the hip is reduced, using a special ‘traction table’ and the outer aspect of the upper femur is exposed. A guide wire inserted up the neck of the femur with the aid of an imaging x-ray. When this wire is in the correct position a channel is made over it into the head of the femur using a special drill and, once this has been done, a large diameter screw is inserted into it. A plate which locks into the screw is applied to the upper femur with screws to hold the damaged bones together.

 

Fractures of the femoral shaft

Fractures of the femoral shaft usually occur in young people. The bone is hard and strong and it requires a much more violent force to break it than that of elderly people. As a result there is a much greater incidence of associated injuries with fractures of the shaft of the femur than with those around the hip. A relatively low force applied to the femur will simply cause it to break in two. If, however, a very large force is applied to the bone it may shatter into several pieces, giving rise to a ‘comminuted’ fracture. The violence associated with a fracture of a femur can damage other areas of the body, leading to life threatening injuries to the head, heart or chest. Widespread tissue damage will lead to excessive blood loss. The injury to the bone itself can cause the development of ‘shock lung’ in which a severe metabolic derangement may take place.

Once the individual has been stabilised after injury there are essentially two methods open for treatment of these fractures. Traction was once the only method of treatment and still has its place today. Nevertheless, this requires prolonged bed rest in hospital and has been largely superseded by operative methods using either a plate and screws on the outside of the bone or a nail inserted up its centre.

Both methods of treatment have their possible complications. The bone can exhibit difficulties and delays in healing with both operative and non-operative methods. Traction can result in some disappointing cosmetic results but, conversely, operative treatment is much more likely to lead to infection and may not entirely eliminate deformities. However, that considering the number of fractures of the femur which do occur, the number of complications are relatively small.

 

Fractures of the tibial condyles

The knee is in an exposed position and in the course of activity, especially during vigorous sports, is vulnerable to forces applied to the lower leg. If these forces are applied from side to side and are too great for the bones to sustain, the rounded condyles of the distal femoral will be rammed into the upper surface of the tibia causing it to collapse. The exact configuration of the resulting fracture will depend upon the the strength of the bone and the degree and direction of the force applied. A relatively minor force applied to weak bone will cause an indentation into the flattened surface of the tibia. A severe force, applied to relatively strong bone, will cause a portion of the tibia to shear off as well as indenting its upper surface.

The effect of such a fracture is to render the knee unstable which, unless it is only a small indentation, leads to a disabling deformity of the joint. For this reason it is necessary to reduce and stabilise these fractures, which can be done by a variety of methods which include screws, plates and external fixators. The displaced fragment sheared off the bone can be supported by a metal plate contoured to the surface of the bone. The depressed portion of the bone needs to be supported by a bone graft or bone substitute to prevent it from collapsing once again when weight bearing is commenced.

All of what has been said about the femur applies to tibial fractures as well. Fractures of the tibia, however, are further complicated by two factors – the bone is very close to the skin, and the blood supply to the bone in this region is much poorer.

The fact that the tibia bone is close to the skin results in a much greater incidence of ‘compound’ fractures, i.e. fractures which are associated with tears and lacerations of the surrounding skin and muscles. There is a much greater incidence of infection in these types of fractures than those which are not accompanied by damage to the overlying skin.

The fact that the blood supply to the bone is relatively poor results in much poorer

 healing of the bone as the necessary nutriments are not made available to it.

There are a variety of methods available to treat fractures of this bone. As it is close to the skin it is amenable to being held by a simple external plaster cast. A more advanced method of treatment is to use an ‘external fixator’ which is an external constraint which holds the bone by way of pins through the skin. More involved is the use of various internal pins and nails which are passed up the central medullary canal of the bone.

 

Fractures of the ankle

The normal foot is a wonderfully balanced organ designed to carry the body at varying speeds over all types of terrain. Being relatively flat it is fairly stable structure. The ankle is a joint designed to move only in one direction, the chunky portion of the underlying talus being held by the two malleoli of the tibia. The ankle joins the foot to the lower leg and, in this position is very vulnerable, particularly if the individual slips. Should this occur the foot may be caught and fixed to the ground by the weight of the body while the body itself moves in another direction. This, particularly if accompanied by a twisting motion, is often enough to snap the malleoli which make up the ankle. With walking being the main mode of peoples transport this is a relatively common injury.

The aim of treatment of any fracture of the ankle is to restore the malleoli to their anatomical position until they heal, thereby regaining their grip on the underlying Talus. This restores the body’s control of the foot and, hopefully, allows the affected individual to walk normally again.

• This aim may be accomplished in one of a number of ways. Should the displacement of the ankle not be too great, or there is a contraindication to surgery, the ankle may be held with an external cast. Sometimes it is necessary to manipulate the fracture to realign the displaced bones. The problem with this form of treatment is that the bones can ‘slip’ in the cast.

• The fracture may be exposed surgically in order to realign the fragments of bone to their proper position. When this has been achieved the fragments can be held by a combination of wires, screws, pins or rods until the bones have united. The problem with this form of treatment is that the wounds can become infected with further morbidity to the individual.

In whatever way the fracture of the ankle is managed it may cause the affected individual some discomfort for a time. A fracture of a bone is painful and surgery will add to this for a while. It may be several weeks before all the discomfort has gone and walking may be difficult during this period and require the aid of crutches. A cast, if used, may make the leg feel heavy and cumbersome. Even when healing is established the ankle may remain stiff and swollen for several months. It therefore behoves anyone with a fracture of the ankle to maintain movement in the joint as much as possible and, for this, the assistance of a Physiotherapist may be invaluable.

 

Fractures of the Calcaneus

The calcaneus bone makes up the heel of the foot and, in this position, is quite vulnerable to injury. Fractures of this bone occur relatively frequently and are most commonly the result of a fall or jumping from a height.

On landing the full force of the falling body is concentrated through the heel. If the calcaneus is not strong enough to sustain this impact it collapses under the load and typically a portion of its rear articular surface is driven into the body of the bone, causing it to burst into various fragments. 

After recovery problems are commonly experienced with this type of fracture. The ability to walk can be affected if there is flattening of the heel as this impairs the ‘heel-strike’ phase of gait. In addition, because of the loss of the heel, there may be reduced ability of the foot to ‘push off’ while walking. This may be a good arg

ument for reduction and fixation of the fracture. Loss of motion of the subtalar joint, between the talus and calcaneus bones, reduces the ability to walk over uneven ground. Whatever the form of management, the foot can later become painful.

A displaced fracture of the calcaneus is thus a complex injury and there is still much debate as to the best form of treatment. Both ‘operative’ and ‘non-operative’ methods have their protagonists. Although operative methods of treatment of this fracture are beset by problems with wound healing and infection the incidence of these complications are relatively low, particularly if the heel is not too swollen at the time of surgery. On the other hand, the direct injury of the articular cartilage may, in itself, lead to a later arthritis of the subtalar joint despite anatomical reduction of the fracture because of the death of the injured cartilage. Nevertheless, on balance operative management may offer the best chance of restoring the heel to the foot and may, at least. allow relatively normal walking.

During the operation the heel is approached from its outer aspect. The depressed fragment of bone, if present, is elevated out of the body of the calcaneus bone and the displaced fragments are restored as close as possible to their anatomical position and held with a combination of plates and screws. Any defect in the bone is filled with bone graft or bone graft substitute.

After the operation it is necessary to protect the heel by not putting any weight on it for several weeks and it is thus necessary to use crutches to walk. The foot commonly remains stiff and swollen for several months and a prolonged course of physiotherapy is necessary to help restore movement to the affected joints.

It is the aim of all these fracture treatments above to return the injured fragments of bone into their correct position and hold them satisfactorily until the bone has healed and thereby allow the injured person to return to as close as possible to his (or her) normal life.