Epidemiology and Pathophysiology of Amputation
Ken Pitetti, Ph.D., Professor, College of Health Professions, Wichita State University
Amputations are commonly divided into two major categories: upper-extremity (UE) and lower-extremity (LE) amputations. The majority (i.e., 80%) of LE amputations are caused by peripheral vascular disease and diabetes. Trauma due to vehicular accidents or job-related accidents is the second most common cause of LE amputations. Trauma due to vehicular accidents, severe lacerations from tools and machinery, and frostbite, is the major cause of UE amputations. Curative treatment of tumors is an additional cause of both types of amputations.
LE amputations are commonly classified into the following categories:
- toe and partial foot amputation (i.e., Symes);
- unilateral (i.e., involvement of only one leg) below-knee;
- unilateral above-knee;
- hip disarticulation and hemipelvectomy;
- bilateral (i.e., involving both legs) below-knee;
- bilateral above- and below-knee (i.e., one leg amputated above the knee, one leg amputated below the knee); and
- bilateral above-knee (i.e., both legs amputated above the knee).
Energy expenditure of ambulation is higher for LE amputees when compared to either non-disabled peers or UE amputees. Indeed, the energy cost of walking is directly related to the level of amputation. For instance, Huang and colleagues (1979) reported that even when LE amputees were allowed to choose their own comfortable walking speeds, the mean energy cost was 9% higher for unilateral below-knee amputees, 65% higher for unilateral above-knee amputees and 280% higher for bilateral above-knee amputees when compared to their non-disabled peers. The higher the energy cost of walking, the more work it takes to ambulate and, therefore, the less ambulation the LE amputee is likely to do. This contributes to a sedentary lifestyle. Studies have shown that non-vascular LE amputees have higher rates of cardiovascular disease, hypertension and adult-onset diabetes (Type II) (Hrubec and Ryder, 1979; Rose et al., 1987) when compared to the non-disabled population. Sedentary lifestyle was listed as the major contributing factor for the increase in these secondary diseases. These findings accentuate the importance for LE amputees to include physical exercise and activity in their lifestyles.
UE amputations are commonly categorized as below-elbow or above-elbow amputations and shoulder disarticulation. Because UE amputations have little effect on the individual's walking or running ability, UE amputees have no greater risk of cardiovascular disease, hypertension, obesity, or Type II diabetes than non-disabled individuals (Hrubec & Ryder, 1979; Rose et al., 1987).