Health

Which are more common, lower limb or upper limb amputations?
In the United States and most industrialized countries, lower limb amputees tend to be more common than upper limb amputees.

What are the common causes of adult amputations?
There are various causes of adult upper and lower limb amputation. Most amputations occur in people older than 65 and are due to some type of associated disease like peripheral vascular disease (PVD) or diabetes. Amputations, when they occur in the younger age groups, are more likely due to trauma. In general, men tend to have amputations more than women do, and upper limb amputees tend to occur more often in younger adults.

Upper limb amputations are most often due to some type of accident or trauma. In contrast, particularly in developed countries like the U.S., approximately 85 percent of acquired adult lower limb amputations are due to PVD, which tends to occur in the older population. Peripheral vascular disease is defined as any condition that affects the blood supply to the limb, causing the limb to be susceptible to poor wound healing and infection. Approximately 25-50 percent of amputees with vascular disease have diabetes mellitus (DM). That fact is attributable to obesity, which is increasing in most countries like the U.S. Worldwide, approximately 50 percent of all lower limbs amputations are performed on patients with diabetes, and approximately 5-15 percent of all persons with diabetes will undergo some type of lower limb amputation. Because of the concomitant PVD, diabetics have a 12-15 times higher risk of having an amputation compared to non-diabetics.

Other causes of PVD include atherosclerosis (hardening of the arteries), frostbite and Buerger’s disease. Buerger’s disease is a condition where blood vessels in the limbs become diseased in individuals who smoke. This condition is more common in men under the age of 50. Other risk factors for PVD include the presence of high blood pressure, high cholesterol, neuropathy (sick nerves) and a history of smoking.

One of the biggest problems facing older lower limb amputees with PVD is that there are often other illnesses that can affect the function and lifespan of the individual. For instance, a significant number of amputees with PVD may die of a heart attack or have some other cardiac disease. A somewhat frightening statistic is that up to one-third of amputees may die within six months of having an amputation when it is due to vascular disease. Additionally, 30 percent will have another amputation of the other leg within 2-3 years.

Some other medical problems may also affect function after an amputation. Approximately 10 percent of older amputees with PVD also suffer from a stroke at the time of their amputation; the risk of having an amputation increases on the side of the stroke. The decreased blood supply, impaired sensation from the stroke and reduced awareness of the affected limb may all contribute to the increased risk of amputation for the stroke patient. Adequate use of the hand on the side of the stroke is a good predictor of whether the amputee with a stroke will be able to function with a prosthesis. Unfortunately, being older, obesity, poor memory, poor single-leg balance and having an amputation higher up on the leg are all associated with poor outcome following an amputation. Although these statistics can be somewhat overwhelming, they are mentioned so that amputees understand the value of good health maintenance and realize the importance of obtaining proper medical management so as to prevent additional complications and limitations from occurring.

How common is trauma and other causes of amputation?
Although PVD accounts for the majority of lower limb amputations in the U.S., trauma, tumors and infections make up the rest of the causes. Congenital (those occurring prior to birth) limb deficiencies are discussed in the pediatric section and will not be covered in this section. In developing or poorer countries, trauma is actually the leading cause of amputation over PVD. This is most likely because of the lower incidence of obesity and resultant diabetes in such countries as well as the higher exposure to farming equipment, which can frequently cause limb amputations. Certainly countries involved in a war or where people are exposed to land mines and other explosive devices are also at a higher risk of having people suffer an amputation.

In the U.S., 70 percent of traumatic amputees affect the upper limb with the majority involving the thumb and fingers. Common settings where these amputations occur include the home and place of work. Traumatic amputations can be due to using power saws and other heavy machinery as well as electrocution or burns. Motor vehicle collisions (including those of motorcycles), gunshot wounds from violence and animal attacks also contribute to traumatic limb amputations. The added advantage that most traumatic upper and lower limb amputees have over others with PVD  is that they are often younger and do not have the related medical problems that come with age and having diabetes. Therefore, their ability to maintain an active lifestyle with or without an artificial limb or prosthesis is much greater.

Tumors that necessitate amputations of the limb occur in bone, soft tissue and skin. Unfortunately, these tumors often require that more of the limb be removed to adequately treat the underlying disease and may result in a very short amputated limb. People with amputations due to an underlying tumor or infection also need to overcome the associated disease processes and complications from treatment like chemotherapy or radiation. The combination of both of these factors may hinder the rehabilitation process. However, once the tumor or infection has been adequately treated and barring any other associated illnesses, one should be able to incorporate a prosthesis into normal function.