Amputation is associated with diabetes, peripheral vascular disease, trauma, infection, and malignancy. Upper limb loss is commonly associated with trauma. Manual control systems remain the primary prosthetic management, although advances are being made in myoelectric, bionic, and replantation or transplantation technologies. Early interdisciplinary team involvement for education and early prosthetic fitting are keys to successful prosthetic upper limb amputation outcomes.
Demographics, Incidence, and Prevalence
In the United States, an estimated 185,000 people undergo amputation of the upper or lower limb each year. In 2008, it was estimated that 1.9 million people were living with limb loss in the United States. Approximately 500,000 people had minor (fingers or hands) upper limb loss, and 41,000 people were living with major upper limb amputations. Trauma accounts for 90% of all upper limb amputations. Finger amputations represent the highest percentage (78%). Excluding finger amputation, the most common upper limb amputations are located at the level of the forearm (transradial) and humerus (transhumeral). One-fifth of all combat-related major amputations involve the upper limb. Two-thirds of amputations that result from trauma occur among adolescents and adults younger than 45 years. Males account for greater than 75% of people with upper limb loss.
An estimated 4.1 per 10,000 babies are born each year with a limb difference. Congenital deficiencies are more common in the upper limb (58%) than in the lower limb, and they occur slightly more often in boys than in girls. The most common congenital amputation is at the left short transradial level. Teratogenic agents and amniotic band syndrome are two causes. The International Society for Prosthetics and Orthotics (ISPO) provides the current classification system for congenital limb difference. A child with a transverse deficiency has no distal remaining parts. In longitudinal deficiencies, distal portions are present but with a partial or total absence of a specific bone.
Nomenclature and Functional Levels of Amputations (eSlides 9.1 and 9.2)
The residual limb refers to the remaining part of the amputated limb. Digit amputations may or may not benefit from prosthetic restoration, primarily depending on the need for prehension. Wrist disarticulation/transradial amputation , elbow disarticulation/transhumeral amputation, and shoulder disarticulation/forequarter amputation are the major upper limb amputation levels. Further categorizations can be made, such as short, medium, or long, to define the residual limb into approximate thirds.
Wrist disarticulation preserves maximum pronation and supination. Transradial amputation results in a reduction of forearm pronation and supination. Elbow disarticulation creates prosthetic fit difficulties that are related to suspension and elbow joint placement. With transhumeral amputation, the more humeral length preserved, the more optimal the prosthetic restoration. Shoulder disarticulation and forequarter amputation are usually related to malignancy or severe trauma, and prosthetic acceptance is low.
Principles of Limb Salvage and Amputation Surgery
Limb-sparing procedures have become possible because of advances in imaging, reconstructive surgery, microsurgery, and cancer treatment. The best decision is one formed by the consensus of experienced trauma, oncology, and rehabilitation specialists.
The mangled extremity syndrome is defined as a significant injury to at least three of the four tissue groups (skin or soft tissue, nerve, vessel, and bone). The mangled extremity scoring systems have been shown to be poor predictors of amputation or salvage for functional outcome.
Once it has been decided that amputation is more appropriate than limb salvage, the team must determine the most distal level possible on the basis of the principles of wound healing and functional prosthetic fitting. Remnant muscles may be retained by myodesis, in which the deep layers are sutured directly to the periosteum, or by myoplasty, in which the superficial antagonistic muscles are sutured together and to deeper muscle layers.
Neuroma formation is a normal and expected consequence of amputation. Nerves should be withdrawn from the wound, sharply divided, and allowed to retract under the cover of soft tissue.
Management: Preamputation, Preprosthetic, and Prosthetic Rehabilitation (eSlide 9.3)
The team approach to amputee rehabilitation ideally begins in the preamputation phase whenever possible. The surgical and rehabilitation teams educate and counsel each other and the patient. It is important to include family members and other supporting individuals in the counseling. Important discussions need to be held with the patient about the planned surgical outcome and postsurgical period. This should also include a discussion about the different types of pain that might occur, the prevention of possible complications, and a preview of potential functional outcomes. An amputee peer visitor may be helpful. The Amputee Coalition of America has an array of resources to assist with this process.
The focus of immediate postamputation period is to control pain and edema, promote healing, prevent contractures, initiate mobilization, and continue counseling and education.
Pain control requires an early aggressive approach that considers multiple potential pain generators in the postsurgical period. Patient-controlled analgesia is transitioned to regularly scheduled long-acting and short-acting oral opioids. Understanding the characteristics of postsurgical residual limb pain (RLP) and phantom limb pain (PLP) allows the clinical team to wisely choose pain interventions. RLP is located in the remaining limb and is generated from soft tissue and musculoskeletal components. PLP is pain in the absent limb and is considered neuropathic. PLP is typically more intense at night and is characterized as burning, stabbing, or numbness/tingling. Phantom sensations occur in more than 70% of amputees and do not have to be treated unless painful and disruptive. Medications known for controlling neuropathic pain include anticonvulsants, such as gabapentin and pregabalin, and antidepressants, such as tricyclic antidepressants and serotonin-norepinephrine reuptake inhibitors.
The new amputee should be taught how to change dressings and use desensitization techniques. Counseling and mirror therapy may be helpful with pain control.
Edema control is important for limb shaping and protection, and it may reduce pain. An immediate postoperative rigid dressing (IPORD) can be placed in the operating room. Elastic shrinkers, gel liner sleeves, or low-tension figure-of-eight ace wraps may also assist in this process and are more commonly used. Proper tension and donning technique reduce complications associated with excess skin pressure or abnormal shaping for prosthetic fitting. Ideally, the residual limb will have a cylindrical appearance before prosthetic fitting. Soft tissue defects, including scarring and grafting, are common challenges. Early prosthetic fitting is important because prosthetic acceptance declines if fitting is delayed beyond the third postoperative month.
Activities of daily living (ADL) are mastered with one hand and with the use of adaptive equipment. Because balance is often disrupted in a new amputee, goals should include strengthening of the trunk and lower limbs using isometric exercise and aerobic training. Motor training with neuromuscular reeducation is conducted to increase muscle activity at potential myoelectric control sites.
Prosthetic Training
The prosthetic training phase begins with the delivery of the prosthesis. Initial focus is on donning and doffing as well as on wearing the prosthesis for short periods, with close monitoring of the residual limb skin. ADL are then incorporated, followed by higher-level homemaking skills and community reentry activities such as driving, work, and recreation.
Upper Limb Prostheses
Prosthetic fitting options include the passive system, body-powered system, externally powered system, and hybrid system. Each patient’s functional and vocational goals, geographic locations, anticipated environmental exposures, access to a prosthetist for maintenance, and financial resources need to be considered.
A passive system is in part cosmetic but also functions as a stabilizer. It is fabricated if the patient does not have enough strength or movement to control a prosthesis or accomplishes tasks without device movements. Sometimes, young children initially use passive upper limb prostheses for balance and crawling. A body-powered system prosthesis uses the patient’s own residual limb or body strength and range of movement (ROM) to control the prosthesis. An externally powered system uses an outside power source, such as a battery, to operate the prosthesis. A hybrid system uses components of both types of controls.
Socket, Suspension, and Control Systems (eSlides 9.4 to 9.10)
Upper limb sockets are typically double walled. They may also contain an inner flexible thermoplastic liner to allow for growth and other fluctuations in size. Donning sleeves may be employed to don a socket. Gel liners with external sleeves, lanyards, seal-in rings, and locking pins may be used for the limb-to-device interface and suspension of devices. Prosthetic sock ply may be used to adjust fit for changes in limb volume. An elevated vacuum system with one-way air valves may also improve suspension of devices. The shorter the residual limb or the heavier the anticipated workload, the more necessary the proximal anchoring of the prosthesis with single or polycentric hinges and shoulder harness systems. Flexible hinges allow for some pronation and supination.
A figure-of-eight or figure-of-nine harness is used for control and suspension. Shoulder flexion and biscapular protraction increase the excursion of the cabling system and control the terminal device, elbow joint, or both. If amputees are given training regarding both myoelectric and body-powered prostheses , they will self-select their primary choice, although they may use either for different activities. Body-powered or manual-controlled prostheses use forces generated by body movements, which are transmitted through cables, to operate joints and terminal devices. Body-powered prostheses give higher sensory feedback and are more durable, less expensive, and lighter than externally controlled prostheses .
Externally powered prostheses use muscle contractions (myoelectric controlled) or manual switches to activate the prosthesis. Prostheses powered by electric motors can provide more proximal function and greater grip strength, along with improved cosmesis.
Externally powered prostheses require a control system. With myoelectric control, muscle contractions are detected by surface electrodes, and these surface electromyographic signals are transmitted to prosthetic motors. The patient uses antagonist muscle contractions or contractions of different strengths to differentiate between flexion and extension of the prosthesis.
Switch-controlled externally powered prostheses use small switches to operate the electric motors. These switches are typically enclosed inside the socket or incorporated into the suspension harness of the prosthesis, such as the “nudge,” which is operated by the chin depressing the switch on a chest strap. A hybrid system incorporates both power options.
Shoulder disarticulation has two commonly used socket designs. The complete enclosure shoulder socket encases the shoulder and may be poorly tolerated because of its weight. The X-frame socket uses very rigid materials to maintain a shape that will lock into the wedge-shaped anatomy of the upper torso to provide a secure suspension.
Terminal Devices, Wrist Units, and Elbow Controls (eSlides 9.11 to 9.14)
Multitudes of terminal devices are available for upper limb amputees, although the functionality of these devices is limited. Terminal devices are generally grouped into one of two categories: passive or active . Passive terminal devices may provide some function and cosmesis. Examples of functional passive terminal devices include the child mitt frequently used on an infant’s first prosthesis to facilitate crawling and the ball handling terminal devices used by older children and adults for ball sports.
Active terminal devices most commonly involve hooks and artificial hands . These may be operated with a manual or external control. External control for heavy-duty prehensile activities may be performed using the Greifer terminal device. Cable-operated terminal devices (hooks or hands) can be of a voluntary opening design (most commonly used) or a voluntary closing design . With a voluntary opening mechanism, the terminal device is closed at rest. The patient uses the control cable motion to open the terminal device against the resistive force of rubber bands (hook) or internal springs or cables (hand). With a voluntary closing mechanism, the terminal device is open at rest. The patient uses the control cable motion to close the terminal device, grasping the desired object.
In general, hook-style terminal devices provide the equivalent of an active lateral pinch grip, whereas active hands provide a tripod or three-point chuck grip. Many different options are available for terminal devices that address vocational and avocational hobbies or sports.
With myoelectric control, it is possible to initiate palmar fingertip grasp by contracting residual forearm flexors and to initiate release by contracting residual extensors. Various types of electronic hands and terminal devices are available. In addition to tripod and lateral tip pinch grips, newer myoelectric devices may offer precision, hook power, and spherical grip patterns. The most advanced prosthetic upper limbs commercially available are the i-Limb, BeBionic, Contineo, and Michelangelo hand. The advent of self-powered digits also makes it possible to replace as many fingers as necessary for a partial hand amputee.
The wrist unit can be positioned manually or with external power (myoelectric or switch). It is held in place by a friction or mechanical lock. Options include a quick disconnect unit and a flexion unit.
Manual elbow systems include single, polycentric, or flexible hinges for below-elbow amputees, and cable-controlled or spring-loaded systems for above-elbow amputees. External controlled systems include myoelectric and switch-operated devices.
Advances in Technology
Osseointegration is an emerging surgical technique for direct skeletal attachment of the prosthesis. It entails the use of a metal spike that is inserted into the terminal end of the bone, which is eventually connected to the prosthesis after completion of a multistage surgical procedure. Benefits include improved suspension, control, and proprioception, whereas risks include infection and device loosening. Targeted muscle reinnervation (TMR) rewires the nerves that no longer have innervation points to the pectoral muscle. Wireless and brain electrodes have been developed that can be implanted into muscle and sense nerve impulses, respectively. Signal technology, known as advance pattern recognition (APR), can provide prosthetic control input. The United States Defense Advanced Research Projects Agency (DARPA) funds research to advance prosthetic technology.
Hand Replantation and Transplantation
Hand replantation (HR) of traumatically amputated limbs is now possible. All indications for replantation must consider the patient’s general health; the limb ischemia time; and the level, type, and extent of tissue damage. HR requires prolonged recovery time, multiple procedures, and motivated patients. Because nerves transected in the proximal arm must regenerate over a considerable length, only limited motor return is typically seen in the forearm and hand, particularly the intrinsic muscles of the hand. Useful functions of the wrist and hand are unusual and limited at best. Hand transplantation (HT) is now performed on a limited basis in the United States. Selection of the appropriate patient, detailed preoperative planning, and precise surgical technique are of paramount importance. Following HR or HT, active and passive exercises to improve ROM, grip strengthening exercises, and sensory reeducation are required over several years.
Conclusion and Follow-up (eSlide 9.15)
Lifelong follow-up by the rehabilitation team, including the physiatrist, improves outcomes. After discharge from the therapy program, the amputee should be regularly monitored in an outpatient clinic by the rehabilitation team. Follow-up may be the most important aspect of prosthetic rehabilitation and yet is often neglected. Issues such as pain, depression, skin irritation, limb size change, and activity change are all more easily addressed early and thoroughly by the team to encourage continued prosthesis use. Many aspects of upper limb prosthetic rehabilitation cannot be addressed until the patient has had time to become acclimated to the amputation.
The successful long-term use of an upper limb prosthesis depends primarily on its comfort and perceived value to the amputee. Careful attention to follow-up adjustments and prescription revisions on the basis of the amputee’s changing needs are essential factors for successful prosthetic rehabilitation.
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