CHAPTER 73 Elbow Disarticulation Amputation

INTRODUCTION

Over the years, advances in upper extremity prosthetics have included improved surgical techniques, preoperative management, postoperative management, and advances in prosthetic technology. In the past decade, the greatest advances have occurred in prosthetic technologies, fabrication techniques, and components to more effectively replace the lost function of the extremity.⁷

DEMOGRAPHICS

Trauma is the leading cause of upper extremity limb loss, accounting for 80% of upper extremity amputations. Tumor is the most common cause of upper extremity amputation in children. From 1988 to 1996, the rate of trauma and cancer-related amputations declined. This decline was likely due to improved surgical reconstruction, advances in limb-sparing techniques, and prevention through improved occupational safety awareness.⁶

Following trauma, the decision to attempt limb salvage or proceed with amputation is complex. There is a bias toward limb salvage in upper extremity trauma surgery. The functional demands of the upper extremity are different from the lower extremity. Lack of weight bearing forces, the ability to function with partial sensation, and limited function of upper extremity prostheses are reasons sited for limb salvage and reimplantation.⁸

ELBOW DISARTICULATION AMPUTATION

Elbow disarticulation has advantages and disadvantages when compared with the transhumeral level of amputation. An elbow disarticulation amputation allows anatomic suspension, rotational control of the prosthesis, and reduces rotation of the socket on the residual limb. The major disadvantages are the suboptimal cosmetic appearance and limited availability of elbow components. The external hinge elbow mechanisms for elbow disarticulations are not very cosmetically pleasing.

In children with upper limb deficiency or amputation, growth and development, bony overgrowth and more rigorous use of a prosthetic device need to be considered. An elbow disarticulation amputation level for this population optimizes residual limb length and avoids bony overgrowth. The slowed humeral growth after elbow disarticulation results in a humeral length at maturity that allows the use of a prosthetic elbow while retaining the suspension and rotational control of an elbow disarticulation.¹ In children, transhumeral amputation results in a high incidence of bony overgrowth. An elbow disarticulation preserves the epiphysis, prevents bony overgrowth, and maintains growth potential; therefore, elbow disarticulation is the level of choice.²

AMPUTATION SURGERY

Controversy exists whether to perform a long transhumeral amputation or an elbow disarticulation. Amputation surgery should be viewed as a reconstructive procedure. The basic principle of all upper limb amputations is preservation of maximal length consistent with optimal function, control of disease, and satisfactory surgical wound management. Adherent scarred distal tissues or redundant soft tissue should be avoided.

SKIN

There is no particular type of skin flap configuration that is better than another. When the soft tissues are normal, equal anterior and posterior flaps are generally preferred. However, skin flaps for traumatic amputations should be fashioned in any manner possible that preserves length. The nature of the trauma, including burns, may require extensive modification of the classic equal flap closure. Skin grafts are not a contraindication to prosthetic fit. Their use may be indicated, particularly in burn amputations. Skin on upper limb amputations is far less subject to pressure, shear, and stretching than it is in the weight-bearing lower limb. The skin that is used to close an amputation should be sensate and well vascularized.

NERVES AND BLOOD VESSELS

Major nerves about the elbow are transected sharply under tension. The transected nerve is allowed to retract into the adjacent soft tissues, away from the amputation site and away from the areas where it could become adherent and a source of pressure irritation from the socket.

Meticulous hemostasis is mandatory to avoid postoperative hematoma formation. All wounds are drained for 48 hours postoperatively.

Through-elbow amputation is carried out as a true disarticulation (Fig. 73-1). Minor contouring of the margins of the distal humerus is usually required to eliminate sharp condylar prominences. For above-elbow amputations, the bone edges should be slightly beveled so that there are no sharp prominences or rough bone edges.

FIGURE 73-1 Cross-section of the elbow disarticulation before closure of the myoplasty. The myoplastic flaps must be sectioned with sufficient length to permit closure without tension

MUSCLE STABILIZATION

Whenever possible, the sectioned muscles and tendons are sewn to each other over the end of the humerus at the amputation site (Fig. 73-2). If possible, the triceps tendon and aponeurosis is retained and brought forward through and over the trochlea to be sewn under minimal tension to the brachialis muscles. The biceps tendon also can be interwoven into the brachialis muscle near the amputation site, giving excellent residual limb muscle control.

FIGURE 73-2 Muscle stabilization using anteroposterior myofascial flaps over the contoured distal humerus at the elbow level. The flaps must be stabilized directly to the periosteum or bone

Muscle stabilization requires firm fixation to the distal bone. When opposing muscles are sewn to each other over the bone or joint end without firm distal fixation, a “sling-like” effect can develop that causes bursa formation, reduces effectiveness of the muscles, and can be painful. A myodesis with two or four small 1/8-inch drill holes through the distal humerus may be necessary to accomplish good muscle stabilization.

NERVE TRANSFERS

In an attempt to improve functional control of myoelectric prostheses, the possibility of transferring residual nerves to spare muscles in or near the residual limb has been studied. Using nerves to reinnervate targeted muscle, the surface myoelectric signals from these muscles have been used to simultaneously control multiple degrees of freedom in a prosthesis.¹³

Research into this concept has been promising. Studies have shown that when large nerves (such as the brachial plexus nerves) are transferred onto relatively small muscle areas, the recovery of the muscle is very good.¹² With targeted reinnervation, control of a prosthesis will be easier and more natural because the myoelectric signals are physiologically correlated to the movements of the lost arm. Although targeted reinnervation shows exciting potential, ongoing research is needed.¹³

ACUTE POST-AMPUTATION MANAGEMENT

Following surgery, the goals of the preprosthetic period are to

1. Promote residual limb shrinkage and shaping

2. Establish a home exercise program of range of motion (ROM), stretching, strengthening and conditioning

3. Increase upper extremity function

4. Review joint protection principles, energy conservation, and one-handed techniques

5. Optimize tasks required for daily living.

6. Evaluate adaptive and durable medical equipment needs

7. Determine the electrical potential provided by various muscles in the event myoelectric prosthetic components are prescribed.

8. Review the patient’s specific daily living, leisure, and work needs to determine possible prosthetic components and options.

Immediate and early postsurgical prosthetic fitting provides edema control, pain reduction, and protects the surgical incision.¹⁴ Successful prosthetic use is higher when fitting is completed within a “golden period” of 30 days after surgery.¹⁴ If prosthetic fitting and training are delayed, the patient can become adept at one-handed techniques, making it difficult to incorporate a prosthesis in their daily living activities. A second study has shown that even delayed fitting can be successful.²² Common reasons for rejecting a prosthetic limb include the perception of limited usefulness, excessive weight, and residual limb pain.

An early postoperative prosthesis using a plaster cast or a high temperature thermoplastic socket typically can be fit by the third day after surgery. Prepositioned or self-positioned locking elbows are used to avoid excess elbow motion and shearing along the surgical incision. If there is concern about healing of the surgical incision, a stump protector (rigid removable dressing), compressive dressing, or soft dressing can be used until the incision has healed and the patient is ready to be fit for their first definitive prosthesis.