The presence of peripheral arterial disease in patients with diabetes who had undergone an initial minor foot amputation significantly increased the risk for a subsequent major lower extremity amputation, according to recently published study results. The presence of peripheral arterial disease also decreased the interval to major lower extremity amputation after an initial minor lower extremity amputation.

“Approximately 75% of foot amputations are performed on patients with diabetes. The risk factors for lower extremity amputation in diabetic patients has been well-documented, while risks for reamputation and limb loss are not well defined” the researchers wrote. “In the present study, we sought to discover why some of our patients continued to have minor foot amputations but never went on to lose their limb (a major lower extremity amputation [LEA]), while other patients did. We hypothesized that there would be an increased incidence of our tested risk factors in patients going on to limb loss.”

Results

The patient population consisted of 163 patients with diabetes who had undergone a minor foot amputation and at least one subsequent amputation. Patients were separated into two groups — one group of patients had multiple foot amputations but never went on to limb loss (the minor LEA group), and the other group of patients had limb loss (the major LEA group). The researchers compared the incidence of certain possible risk factors between the two groups, including age, glycemic control, kidney function, previous kidney or kidney-pancreas transplantation, smoking history and presence and severity of peripheral arterial disease (PAD).

The only risk factor that showed statistical significance was severe PAD, which was surprising to the researchers who hypothesized that there would be an increased prevalence of all previously documented risk factors. Overall, severe PAD was noted in 22.23% of patients in the minor LEA group and in 71.15% of patients in the major LEA group. The average interval to major amputation in patients without PAD was 1,180.9 days, while there was an interval of 591 days among patients with mild to moderate PAD and 559.6 days among patients with severe PAD.

“The study shows that arterial inflow to the lower extremities is extremely important in preventing limb loss in diabetic patients. This led us to believe all diabetic patients with risk factors for amputation, especially those with previous foot amputation, should be sent for non-invasive vascular testing. Patients with evidence of PAD should then be promptly referred to a vascular specialist for possible intervention,” Vincent Nerone, DPM, of the Department of Orthopaedics at the Ohio State University Medical Center, told O&P Business News. “The other important point is the need for a ‘team approach’ to limb salvage that many medical centers have established. This includes physicians from multiple specialties such as general surgery, vascular surgery, podiatric surgery, plastic surgery, and infectious disease specialists working together toward the common goal of preventing limb loss. This ensures proper screening, prompt diagnosis of risk factors for diabetic foot complications, and referral to the proper specialist for possible intervention.”

Take-home message

The researchers recognized that their retrospective study had similar limitations to other retrospective studies, including not recording or considering variables affecting the outcomes, such as patient compliance with bracing and prosthesis or presence of foot deformities.

Despite these limitations, according to Nerone, these study results reveal relevant information for diabetics and their physicians.

“All diabetic patients with previous foot amputations should have baseline non-invasive lower extremity vascular testing and this should be repeated at regular intervals,” Nerone said. “Any abnormality should prompt further testing and referral to a vascular specialist for evaluation and possible intervention. This approach may lead to limb salvage.”

Currently, Nerone and colleagues are continuing their examination into preventing poor outcomes after foot amputation in diabetics. This includes prospective studies determining novel ways to identify high-risk patients and providing new interventions to prevent these poor outcomes, especially limb loss. — by Casey Murphy

Disclosure: Nerone has no relevant financial disclosures.