Diaphyseal bone does not exist without an outer cover of cortex in its natural state. Thus it is intuitively physiologic to seal the end of the bone following amputation, and techniques have been refined for performing an osteo-periosteal bone cap over the end of diaphyseal bone. However, even without a surgical osteo-periosteal flap, the end of the bone naturally heals by formation of bone callous and fibrous tissue. When a periosteum cuff is available it may be sutured over the end of the bone, but excessive use of periosteal strips can cause problems. As occasionally seen in traumatic amputations or when the periosteum is circumventially peeled off the bone before sectioning, the residual periosteal strips can slowly form irregular bone spikes. These spikes or bone spurs can cause painful pressure points for the amputee. The surgeon should be aware of this potential problem in order to minimize its occurrence.
The standard protocols for skin closure in any other surgery also apply to closing the wound following an amputation. Dead space should be eliminated and drain systems used when necessary. When closing the wound, opposing tissue layers are sewn under physiologic tension, and care must be taken so that the final closure is neither too light nor too loose. As with all surgery, careful judgement is necessary in the selection of suture and closure technique, and the amputation surgeon must be aware of the options and differences between various techniques. Many patients have only marginal blood supply and the utmost surgical care and technique is required to maximize their wound healing potential.
If primary closure of the wound is not advisable, amputation should be carried out in two or more stages. An initial amputation may be done to provide adequate drainage of infection. This is the recommended course for a preliminary open ankle disarticulation involving a septic patient with a severely infected, non-salvagable diabetic foot. Patients presenting with such a scenario are frequently febrile and bacteremic. The initial open amputation helps to control the infection, eliminate the bacteremia and provide a safer wound environment for a definitive amputation at a later date. Leaving the bone long and avoiding transecting the muscle bellies minimizes the post-operative swelling and edema that often complicates mid-diaphyseal open amputations. When left long, the bone can act as an internal splint, protecting the remaining soft tissue. This will facilitate the later definitive amputation.
Often times a contaminated, open amputation is the result of the original traumatic injury. Contaminated amputations can be treated in a similar fashion to other open amputations. As always, first and foremost the amputation is formed with consideration as to how it will eventually be shaped and closed. Often in trauma cases there is an intermediate zone of tissue. This zone usually requires time to either recover or demarcate, and multiple secondary surgeries can be required before it becomes evident if the involved tissue is viable or must be removed.
Open amputations are not guillotine amputations. In the past the term ‘guillotine amputation’ was commonly used, but both this wording and the particular technique it describes should be avoided. In times of war, guillotine amputation was used to avoid infection. All the different tissues were transected at the same level, much as a guillotine blade would sever a limb. In a guillotine amputation, no flaps were fashioned, no muscle for myodesis was retained and no fasciocutaneous closure was planned. The post-operative plan following guillotine amputation was not to perform a secondary closure, but instead to apply skin traction, daily dressing changes and prolonged wound care. Distal healing with skin traction resulted in fragile, thin, distal coverage that has poor durablity. An eventual revision would often be performed many months later. The guillotine technique is no longer recommended. Even in instances of grave trauma, open amputation with a thoughtful plan for closure is a better option.
The general principles of primary amputation also apply to revision amputation. Revision is necessary if the primary amputation fails to heal, or else if the residual limb is unsatisfactory for prosthetic fitting. Revision may also be necessary if the residual limb does not serve the patient’s functional requirements. With advances in prosthetic devices and interfaces, limbs once historically difficult to fit can now be accommodated for reasonably well. Unfortunately, many modern-day amputations are still poorly done, and these will either develop complications during the healing process, or else require revision surgery at a later date. Better education, more research, and additional refinement of surgical technique are the ways to avoid unnecessary revision amputations.
Revision amputation for pain issues is a viable option only when the etiology of the patient's pain is clearly identified. Such pain problems that are amenable to surgical treatment include redundant tissue, in-folded skin, painful scars, bone prominence, bone spurs, heterotopic ossification, failure of myodesis, distinct and identifiable symptomatic neuromas and some chronic skin conditions, such as epidemoid cysts and chronic skin break down or ulceration. Surgery specifically for the treatment of phantom pain, without clear pathologic etiology, has not been successful.