Amputations And Prosthetics Amputations

There are two types of amputations: disarticulations in which the amputation is carried out through a joint surface; and amputations directly through bone and soft tissues at a particular level depending on the disease process. Amputations are recorded in the earliest medical literature and have subsequently been refined, not only from the perspective of the

Figure 22.23. Total hip replacement - implant failure with a broken femoral stem.

disease process but also the functional and prosthetic requirements that are required following amputation to enhance the rehabilitation of the patient. Amputations have come a long way from being regarded as the last step of failed management to being the first stride in successful rehabilitation of a patient!

The indications for amputations can be broadly classified as:

• Peripheral vascular disease: The vast majority are patients with atherosclerotic disease or vessel disease secondary to diabetes mellitus. In diabetics with small vessel disease developing trophic ulcers with subsequent infection and osteomyelitis, the level of amputation is determined by the patient's age, his functional requirements and mobility and the extent of the disease process. This latter requires a careful assessment of the vascular supply of the limb. The requirements of proximal resection so as to ensure good stump healing must be balanced against those of maintaining adequate stump length for prosthetic fitting so as to encourage the patient to become independent again.

• Post-traumatic: In young adults, particularly men, road traffic and industrial accidents account for the majority of amputations performed in this age group. Most involve the lower limb and the injuries usually have acute vascular and/or neural damage to the limb with associated massive bone and soft-tissue injury. Under some circumstances the damage is irreparable and primary amputation may be the best course of action. In other situations, attempts may be made to debride the damaged soft tissues, stabilize the bony skeleton and repair the neural and vascular supplies in an attempt to maintain the viability of the distal part of the limbs. This approach may restore some functional anatomy but often a prolonged course with multiple surgical procedures is required. The decision between salvage or amputation of a severely injured limb is one of the most difficult decisions an orthopaedic surgeon has to make. Several scoring systems have been devised to predict the results of limb saving surgery. The common ones are MESS (Mangled Extremity Severity Scale), PSI (Predictive Salvage Index) and NISSA (Nerve injury, Ischaemia, Soft-tissue and skeletal injury, Shock, Age of patient). They attempt to quantify the severity of trauma and provide guidelines to decide between amputation and salvage. However it cannot be overemphasized that the final decision must rest on the surgeon's assessment and clinical acumen rather than any scoring system. In those cases where attempted repair proves unsuccessful, a delayed amputation may be deemed necessary. In patients with severe burns, it may be best to delay any consideration of amputation until an accurate demarcation between the viable and non-viable tissues can be delineated.

• Tumours: The commonest indication for amputation in this category of patients is malignant tumours without evidence of metastatic spread where curative resection is the aim. This requires accurate clinical and radiological evaluation to determine the extent of spread of the tumour within the affected limb. Amputation may also be undertaken in patients in whom metastatic spread may have occurred but where the tumour is ulcerating, necrotic and gangrenous and its removal will improve quality of life if not the duration. It is uncommon for benign tumours to require amputation; however, some may interfere with the function of surrounding soft tissues and neurovascular structure to such an extent that amputation and prosthetic replacement may restore a greater degree of functional independence to the patient than local resection. The majority of amputations performed in the paediatric age group are either for malignancy or congenital anomalies (Fig. 22.24). In the last few years advances in chemotherapy, radiotherapy, surgery and the availability of custom made implants and prostheses have considerably improved prognosis and quality of life in these patients.

• Neural deficits: Patients with isolated neural injuries, either post-traumatic or -surgical, and left essentially with a flail limb may also benefit from amputation and prosthetic replacement using the remaining functional muscles to manipulate the prosthesis. Common examples are brachial plexus lesion with a subsequent flail upper limb and

Figure 22.24. Congenital amputation of the foot at ankle joint level.

gunshot or traumatic injuries involving the sciatic nerve and leaving the lower limb flail below the knee. Attempts are being made to repair such neural injuries acutely; however; the recovery period can be prolonged and somewhat unpredictable.

• Infection: Acute infections such as gas gangrene rapidly spreading throughout the soft tissues with associated generalized septicaemia may precipitate the need for amputation to save the patient's life. The level of amputation depends on the degree of septic involvement of the limbs. Other causes of less virulent infection, such as chronic osteomyelitis that fails to resolve following other forms of surgical management, chronic tuberculous involvement of part of a limb or secondary neoplastic involvement of chronic discharging sinuses may also warrant amputation.

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