Ulcers develop in atherosclerosis due to compromised blood supply. The ulcers as a result of trauma or infection are difficult to heal or may not heal at all. Depending upon the severity of the block, there can be gangrenous changes. Smoking, obesity, and hyperlipidemia are the risk factors.

There can be single or multiple sinuses in chronic osteomyelitis. Occasionally these sinuses may not respond to prolonged antibiotics and even to multiple surgeries. Osteomyelitis of the calcaneum may lead to ulcer formation, as heel is a weight-bearing area. Necrotizing fasciitis is yet another serious infection where an early intervention in the form of amputation may be necessary. In advanced uncontrolled infective ulcers, open amputation is indicated (Fig. 27.3). It can be guillotine amputation with revision to more proximal level after control of infection.

In a severely injured limb, the amputation may be the only treatment available. For unsalvageable crush injuries of the limb, the functional results after amputation are better than continuing with prolonged therapy. The various complications associated with a severely injured limb resulting in ulcer formation are uncontrolled soft tissue infection as well as osteomyelitis and infective arthritis and may be gangrene. Preserving such disabling parts of body is more frustrating to patients than getting rid of it followed by fitting of prosthesis. Blast injuries and burns are other examples which may result in nonhealing ulcers refractory to treatment.

Pressure ulcers are common and challenging in patients with spinal cord injury. Proximal amputations of the lower limbs can be considered as part of the treatment for complicated pressure ulcers as it would reduce the number of hospital stay and improve the quality of life and functional outcome [4]. A pressure ulcer over a bony prominence may lead to extensive tissue necrosis of soft tissues including muscle and supporting structures with osteomyelitis of underlying bone. Loss of sensations in lower limbs can result in trophic ulcers in the foot and other bony prominences. In Indian subcontinent, Hansen’s disease is an important pathology. Nonhealing ulcers developing over neoplastic lesions (Fig. 27.4) or squamous cell carcinoma developing over chronic draining sinus can be another indication for amputation.

Diabetic ulcers need special mention as they are one of the leading causes of nontraumatic lower extremity amputations (LEA) worldwide [5]. There are many classifications grading the diabetic foot ulcers (DFU). Wagner’s classification [6] is more popular (Table 27.1). In this classification, in grade 4 and 5, amputation is often required. Edo et al. studied the risk factors, ulcer grade, and management outcome of diabetic foot ulcers in a tropical tertiary care hospital and concluded that spontaneous blisters, peripheral vascular disease, peripheral neuropathy, and visual impairment are common risk factors of DFUs [7]. 45.6 % patients presented with Wagner grade 4 and 5 ulcers with the resultant high rate of lower extremity amputations (LEAs). Early presentation and treatment of DFUs can reduce the amputation rates. The effective partial foot amputations in the high-risk diabetic population can minimize the need for major proximal lower limb amputations [8]. Monteiro et al. studied extensively the classification systems for lower extremity amputation prediction in subjects with active diabetic foot ulcer and concluded that though there are numerous classification systems for DFU outcome prediction, but only few studies evaluated their reliability or external validity and reported accuracy measures [9]. Further studies assessing reliability and accuracy of the available systems and their composing variables are needed.