The ankle disarticulation amputation that we now know by the eponym Syme amputation was originally described in 1843 by James Syme (1). He described an elective disarticulation of the ankle joint for tuberculosis of the talus and calcaneus. He listed three advantages over amputation at the transtibial level: “One, the risk to life will be smaller; two, a more comfortable stump will be afforded; three, the limb will be more seemly and useful for progressive motion.” While these insightful observations were made over a century and a half ago, this function and disability-sparing amputation has not gained wide popularity. Syme’s arguments in support of ankle disarticulation can be used as an excellent foundation to appreciate the outcome-oriented lessons learned from this amputation level.

Syme’s first argument was based on a decreased risk of mortality and morbidity. The use of regional anesthesia and a calf-level tourniquet are valuable benefits in a diabetic patient population, which is often complicated with concomitant cardiopulmonary and renal disease. Both short- and long-term mortality and morbidity appear to be less in patients following Syme ankle disarticulation as compared with transtibial amputation (2, 3 and 4). Current databases do not provide sufficient insight whether patients live longer and remain more independent because they have less severe systemic diabetes-mediated organ system disease at the time of surgery, or whether the independence achieved following ankle disarticulation allows them to be more mobile and independent. Syme’s second argument was based on the biomechanics of weight bearing with a prosthesis following amputation. The normal foot is a uniquely adapted organ of weight bearing. The plantar skin is thick and durable, capable of tolerating the application of high focal pressure and shearing forces. The intervening fibrous tissue of the heel pad and forefoot contains specially adapted fibrous septae capable of absorbing and transmitting the engineering loads of weight bearing to the bones of the foot. The multiple bones and joint architecture efficiently absorb, dissipate, and transfer the forces applied during initial floor contact, that is, heel strike, and create a stable platform for propulsion at push-off. When these specially adapted tissues are lost, the weight-bearing loads must be absorbed by a single bony surface area that must dissipate and distribute these forces, as well as create a stable “starting block” for propulsion. Overloading of the amputation stump is therefore responsible for “repetitive stress” mechanical pain, energy-inefficient walking, and tissue breakdown of the soft tissue envelope.

Joint disarticulation takes advantage of bony surfaces that achieve load transfer more efficiently than with transosseous amputation. The pressures applied during weight bearing can be dissipated over the expanded surface area of the articular surface. The bone and cartilage of the metaphyseal end of the bone is more capable of dampening the impact forces associated with weight acceptance. The forces applied during loading are direct pressure, as opposed to the shearing forces applied during the indirect load transfer associated with transosseous amputation. These forces are less likely to lead to ulceration and tissue breakdown of the soft tissue envelope, a lesson that was learned in studying the etiology of tissue failure in the neuropathic foot (5,6).

Syme’s third argument was based on improved rehabilitation and eventual walking independence. The energy cost of walking is decreased, and functional walking independence is increased with ankle disarticulation as compared with transtibial amputation in diabetic dysvascular,
traumatic, and congenital patient populations (2,7, 8 and 9). Patients require minimal postoperative prosthetic gait training following Syme ankle disarticulation and rarely require hospitalization in a rehabilitation unit.