How do post-traumatic amputation considerations differ for the upper and lower extremities?
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Many tools available for limb salvage
The questions of salvage vs. amputation following severe limb trauma invariably come down to an analysis of several questions. Can the limb be salvaged? What is the likely functional outcome and durability of a successful salvage? What is the expected functional outcome of amputation? Not to be completely disregarded, one also must account for the changes in body image and emotional impact of either approach.
With regard to limb salvage, we have many tools at our disposal. Bone can be regenerated by bone transport, massive grafting and free tissue transfer. Soft tissue coverage can be provided with rotational or free tissue transfers. Lost function from muscle and/or neurologic injury can be partly compensated for by bracing, tendon transfer or even fusion, as indicated.
In lower extremity traumatic amputees, most of whom are relatively young, function can likely be restored with proper prosthetic use and rehabilitation. Modern prosthetic designs utilize advanced technology to maximize socket fit, articulation and energy preservation. The energy required to ambulate with a transtibial amputation is roughly 10% higher than normal gait, and that gait may look almost entirely normal.
Functional demands are different for the upper limb. The purpose of the arm is to position the hand in space so it can grasp. The majority of patients still choose mechanical systems that rely on exaggerated body movements to drive a series of cables and pulleys to either open or close a grasping hook. In the absence of any real biofeedback, the functionality of such systems is limited, at best.
Myoelectric prostheses, in which motor-powered articulations can be controlled by the electromyography of a residual muscle, may improve finer motor skills, but their strength and durability are limited when compared to the cable-driven devices. Advanced prostheses can be controlled by targeted muscle innervation, in which the nerve to an effector muscle lost to amputation is transferred to a muscle more proximally that can provide the signals that control a myoelectric prosthesis.
Because functional restoration is not as successful with an upper extremity prosthesis, every effort should be made to salvage an injured arm or hand, even to the point of replantation for traumatic amputation.
James C. Krieg, MD, is chief of orthopedic trauma and fracture care at Rothman Orthopaedic Institute in Philadelphia.
Disclosure: Krieg reports he has stock or stock options with Biostar Ventures, Conventus, Franklin Biosciences, MDLive and Trice Medical; is on the editorial or governing board of the Journal of the American Academy of Orthopaedic Surgeons; receives IP royalties from SAM Medical and from Synthes CMF; and is a paid consultant and paid presenter or speaker for Synthes.
Amputation differences in upper, lower extremities
Several factors differentiate both management and outcomes of upper and lower extremity amputations. For starters, we spend all day on our feet. However, the relative functions expected with a lower extremity prosthesis are relatively basic compared to the dexterity and sensory feedback we desire for optimal upper extremity function. For instance, we want lower extremity prostheses to replicate normal gait patterns as closely as possible, with an emphasis on uniplanar, specifically forward, motion. We are also generally less concerned with fine motor movement and dexterity of the terminal prosthesis, being focused more on stability and optimizing the efficiency of ambulation/mobilization.
Upper extremity amputations may be less common, accounting for less than 10% of the total population of those with limb loss, but they can have a profound effect on a patient’s ability to interact with his or her environment. For example, proximal upper extremity amputations have traditionally required the use of cumbersome, often heavy prostheses that result in poor rates of use. However, this is an exciting time for the advancement of upper extremity prostheses that can improve the amputee’s ability to optimally interact with the environment. Targeted muscle reinnervation, which has historically been used to prevent or treat symptomatic neuromas, is being used to transfer terminal branches to non-anatomic sites within muscle that can be used to control intuitive myoelectric prostheses. In addition, although osseointegration was initially met with some skepticism due to the risk of infection, recent results have been promising. Having a rigid prosthesis that may improve patient independence and eliminate many of the problems associated with traditional sockets, which include skin breakdown and patient compliance, makes osseointegration a promising option, especially for the proximal upper extremity amputation.
There are many differences between upper and lower extremity amputations from reconstructive options to prosthetic goals. Regardless, they can both result in significant disability. Many advances have been made in amputee care in recent years and we must continue to keep pushing the specialty forward.
Daniel J. Stinner, MD, PhD, is an assistant professor in the department of orthopedic surgery and rehabilitation at Vanderbilt University Medical Center in Nashville, Tennessee, and is a lieutenant colonel at Blanchfield Army Community Hospital in Fort Campbell, Kentucky.
Disclosure: Stinner reports no relevant financial disclosures.
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