Surgeon offers cautions and tips on lower limb amputation

When considering lower limb amputation and management, it is important to retain as much of the lower limb as possible, according to John H. Bowker, MD, who discussed basic principles and a wide range of amputation techniques that he has—using his word—“apprehended” over a 52-year career. Dr. Bowker spoke before the Orthopaedic Rehabilitation Association on Specialty Day at the 2010 AAOS Annual Meeting.

“From my point of view, determining where to amputate mostly has to do with wound-healing potential,” said Dr. Bowker. “If there is good wound-healing potential at a distal level, that’s where I’ll amputate. I may have to settle for a higher level if nothing can be done to restore blood flow preoperatively or if trauma has resulted in irreparable damage. But even then, I try to retain the knee joint.”

Avoid guillotine amputations
Dr. Bowker pointed out that longer amputations allow the patient to retain a better feel for ground contact and a better sense of where the prosthetic limb is in space. That translates to shorter rehabilitation times and less energy expenditure when walking.

“That’s very important for people who already have impaired heart and lung function with resultant low energy levels,” he said. Many people who require amputations for vascular disease and/or diabetes also have considerable vascular disease elsewhere in the body. The older and sicker the patient, the longer the residual limb the surgeon should attempt to preserve.”

Therefore, Dr. Bowker recommends retaining as much of the soft tissue (skin and muscle flaps) and bone as possible by avoiding guillotine amputation.

“Guillotine amputations are commonly performed in severe trauma and some cases of infection,” he explained. “But because tissue with good viability can often be found beyond the level of injury or infection, I recommend initially saving all viable tissue and only removing whatever is necrotic or damaged beyond repair. These retained soft tissues are often perfectly good for delayed closure with myodesis, thus saving bone length and providing a stable soft-tissue envelope. Following a guillotine amputation, the surgeon has to shorten the bone—sometimes considerably—to get the soft tissues closed.”

Dr. Bowker also recommends making extra long flaps of soft tissue to compensate for the inevitable flap contracture that occurs prior to delayed closure and also using nonstandard flaps when necessary to preserve limb length. He argued for preserving limb length even when dealing with multiple fractures of the tibia or femur instead of opting for an amputation through the most proximal fracture—a move that may not be necessary.

“Plates or external fixators can be used to immobilize the more proximal fractures. Later, a long amputation with myodesis can be performed.”

Orphan techniques
Although Dr. Bowker covered an array of techniques during his presentation, he drew special attention to two “orphan” amputations that he considered noteworthy.

“Surgeons often haven’t been trained in how to do them,” he explained, “and they may not understand the advantages. The Syme amputation (Fig. 1) is through the ankle joint, saving the fatty heel pad, which is then secured to the distal end of the tibia. Knee disarticulation also has several important advantages over transfemoral amputation.

“One advantage of both these techniques is that they enable end-weight bearing in the prosthesis, so the patient has better proprioception—a better sense of where their prosthetic limb is in relation to the ground,” said Dr. Bowker.

Postoperatively, any joint close to the amputation—the ankle in cases of major partial foot amputations, or the knee for transtibial amputations—should be immobilized, Dr. Bowker advised.

“Maintaining a functional position postoperatively—especially during the painful first weeks after surgery—is very important to prevent joint contractures that may interfere with prosthetic limb fitting,” he said. “After that, patients can usually exercise the joints on their own.

“Immediately following a transtibial amputation, I’ll apply a lightweight cast and change it every week for 3 weeks. With each change, the knee is put through a full range of motion. Following a major partial foot amputation, I always immobilize the ankle joint in a neutral position so that the patient won’t end up walking on the end of the residual foot in an equinus position.”

The orthopaedist is an integral part of the amputation team, which includes a wide array of rehabilitation specialists. He believes that the amputation surgeon—of all the team members—has a unique perspective and should be involved in the entire process, from amputation to long-term outcome.

“The amputation surgeon—whether orthopaedic or some other specialty—can provide prompt recognition of surgically correctable problems,” he said. “If the team doesn’t have someone with amputation surgery expertise, the causes of some problems may go unrecognized, resulting in more and more adjustments to the prosthesis without any real effect. Often, surgical intervention can correct the problem promptly. In the end, it’s all about maintaining people at their optimal level of function.”

Disclosure information: Dr. Bowker—Saunders/Mosby-Elsevier.

Expanded explanations of many of Dr. Bowker’s surgical techniques for amputation can be found in the Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles, Third Edition, edited by Douglas G. Smith, MD; John W. Michae, MEd, CPO; and John H. Bowker, MD, and published by the Academy in 2004.

Peter Pollack is a staff writer for AAOS Now. He can be reached at ppollack@aaos.org