Syme ankle disarticulation in patients with diabetes.

BACKGROUND:
Syme ankle disarticulation is an amputation level that minimizes disability and preserves function, but it has been used sparingly in patients with diabetes mellitus. Surgeons have avoided this level because of the perceived high risk for wound failure, wound infection, or migration of the heel pad, which makes prosthesis use difficult.

METHODS:
Ninety-seven adult patients with diabetes mellitus who underwent Syme ankle disarticulation because of a neuropathic foot with an infection or gangrene, or both, during an eleven-year period were studied retrospectively. Selection of the amputation level was made on the basis of clinical examination and an assessment of the wound-healing parameters, i.e., vascular inflow, tissue nutrition, and immunocompetence. The average age of the patients was 53.2 +/- 17.5 years.

RESULTS:
Eighty-two patients (84.5%) ultimately achieved wound-healing. When threshold levels for vascular inflow (ultrasound Doppler ischemic index of 0.5 or transcutaneous partial pressure of oxygen between 20 and 30 mm Hg) and tissue nutrition (serum albumin of 2.5 g/dL) were met, an overall success rate of 88% was achieved. Total lymphocyte count (an absolute lymphocyte count of 1500) and the smoking of cigarettes during the study period did not appear to impact wound-healing rates. The overall infection rate was 23%, and it was three times greater in smokers. Most infections were managed with local wound care and antibiotic therapy. At a minimum follow-up of two years, all but two patients were able to walk with a prosthesis. Thirty of the ninety-seven patients died at an average of 57.1 months following surgery.

CONCLUSIONS:
The results of this retrospective review support the value of Syme ankle disarticulation in diabetic patients with infection or gangrene. This function-sparing amputation can be successfully performed with a reasonable risk. Patients managed with a Syme ankle disarticulation appeared to remain able to walk better and to survive longer than similar patients who had a transtibial amputation and served as historical controls. In diabetic patients with dysvascular disease who have adequate vascular inflow to support wound-healing (an ultrasound Doppler ischemic index of 0.5 or a transcutaneous partial pressure of oxygen between 20 and 30 mm Hg), the threshold for the wound-healing parameter of serum albumin appears to be as low as 2.5 g/dL.