Hand Amputation

Anatomy and Physiology

Traumatic injury is the most common etiology of hand amputations.[2] Vascular compromise, malignancy, and complications secondary to diabetes mellitus get reported less commonly as reasons for hand amputation.   

Indications

The precise rate of hand amputation in the United States is not well defined in the literature.  Amputations presenting to U.S. emergency departments account for only 0.5% of all upper extremity presenting complaints.[3] This figure, however, includes all upper extremity amputations from shoulder to fingertip. International registries provide some reasonable perspective on the epidemiology of hand amputation. Young, otherwise healthy males are more likely to sustain a hand amputation as compared to females.[4][5] The rate of all amputations in the United States is estimated to double between 2005 and 2050, with a likely commensurate increase in amputations of the hand and upper extremity.[6]

Preparation

Individuals who have sustained a hand amputation typically present to the emergency department. It is essential first to obtain a history and evaluate the injured limb in a timely fashion. The injured hand is generally apparent, receiving the first and most attention. It is critical, however, to evaluate the patient for other injuries before focusing on the hand.  The patient may have other life-threatening injuries that deserve immediate attention. After stabilizing the patient, providers can then evaluate the hand injury. The mechanism of amputation, including whether it was sharp, crushing, mangling, avulsion, high velocity, or explosive, will likely be the primary determining factor in treatment strategy. Additional required information to obtain includes the time of amputation, hand dominance, occupation, and recreational activities. The time course of the injury is also critical to know ischemia time, which affects treatment options. A full medical history is essential, noting tobacco use and vascular disorders in particular, as they can affect treatment options. As in the evaluation of any patient preparing for surgical intervention, it is critical to note the time of last oral intake and the use of any anticoagulating medications.

The physical examination must include a complete evaluation of the entire affected extremity. On inspection, the examiner must note the level of amputation and the digits involved. The quality of involved soft tissue requires examination also, an adjacent burn receive different treatment differently than a clean, sharp injury margin. Additional abrasions or lacerations may also be present. Noting exposed structures, including bone, joint space, tendon, nerve, and vasculature, is essential.  If the amputated part is available, then its condition should be reported. Palpation of the extremity proximal to the amputation may elicit pain indicative of additional injury and requires further investigation. The neurologic examination includes the sensory condition of the median, radial, and ulnar nerves as well as motor capacity of the remaining muscles innervated by the anterior interosseous, posterior interosseous, median, radial, and ulnar nerves. The condition of individual tendons at or near the amputation site requires evaluation. Vascularity evaluation is by assessing the nature of bleeding (pulsatile or continuous), the capacity of a part to bleed, and distal capillary refill time. Providers must remember to determine the overall status of the patient and to address associated acute medical conditions.

Following the history and physical exam, radiographs are the next appropriate step in the evaluation of the patient with a hand amputation. Radiographs of the hand, wrist, and forearm are necessary for any hand amputation. Radiographs of the distal amputated part, if available, should be obtained as well.  If the amputation is not traumatic, then a vascular workup is appropriate. Assessment of perfusion can include vascular pressures, transcutaneous oxygen levels, and arteriography.

Technique or Treatment

Pre-hospital and emergency department management of traumatic hand amputation patients should focus on the medical stabilization of the patient. The injury may not just involve hand amputation, and following proper ATLS (Advanced Trauma Life Support) protocol is critical before treating the often more noticed hand injury. Elevation and compressive dressings can control bleeding; a tourniquet may be necessary.[7] Avoid tourniquet use unless it is mandatory for survival, as this may cause further injury to the remaining limb — control bleeding with pressure.  Tetanus vaccination and intravenous antibiotics administration should begin as soon as possible. The amputated part should be transported with the patient, wrapped in moist gauze, sealed in a plastic bag, and placed on ice.[7] Care is necessary to avoid freezing the amputated part.

There are essentially two definitive options in the acute management of hand amputations: replantation or revision amputation. Indications for replantation for the upper extremity include any pediatric amputation, thumb involvement, multiple digit amputation, and amputations occurring at or proximal to the palm.[7] Therefore, replantation should nearly always merit consideration in a hand amputation. Factors that deserve attention before performing hand replantation include the mechanism of injury, adjacent injury, time from injury, availability of postoperative care, medical and psychiatric comorbidities, occupational and recreational demands, and culture and personal values.[8] Time is a critical factor.  Proximal amputations, such as the hand, can undergo replantation after 6 hours of warm ischemia time or 12 hours of cold ischemia time, defined as 4 degrees Celsius.[9] More distal finger amputations can tolerate longer ischemia times of 12 and 24 hours at warm and cold temperatures, respectively.[9] These times are somewhat flexible, and the limits of ischemia time are under challenge in the literature. Relative contraindications to replant include mangled extremity, irreparable adjacent soft tissue, single-digit amputation through Zone II, and patients with medical comorbidities that preclude surgical intervention.[7] Advanced age, independent of overall health, is not a contraindication.[10]

If replantation is the best option for the patient, following surgical debridement of the wound, bony fixation is the first step in replantation.[7] This process establishes a stable foundation for vascular repair and tendon tensioning. The remaining order of soft tissue fixation is controversial. Structure-by-structure reconstruction has demonstrated increased efficiency and yields a shorter time to revascularization than digit-by-digit repair.  The remaining specifics of techniques in replantation are beyond the scope of this article. After surgery, patients must be monitored in the hospital for several days and may require repeat surgery for a dysvascular hand. A certified hand therapist is critical in a patient's recovery after these severe injuries to protect the repaired structures while working on regaining motion and function. Tendon adhesions and joint stiffness are common after these injuries.  

The revision of a hand amputation in lieu of a replantation attempt requires careful consideration. Although a hand amputation is nearly always an indication for replantation from a biomechanical perspective, the specifics of the injury and the patient comorbidities may preclude this as an option.  Amputation would be the preferred treatment when the amputated part is damaged or contaminated beyond resolve, such as in a crush injury.  Prolonged ischemia time outside of the window outlined above also indicates preferential amputation. Primary revision amputation is preferable for the patient who is medically unsuitable for the rigors of replantation and rehabilitation; advanced age alone is not a contraindication to replantation.[7] When revision amputation does take place, the primary concerns are the preservation of function, limb length, and shape.  Increasing residual limb length typically yields more function through a longer lever arm while limb shape accommodates a better fitting prosthetic.[11]  Although technology is improving, prosthetics cannot yet match the sensory and motor finesse of a native hand.[11]  Regardless of the chosen treatment method, the goals remain the same: maximize the function while limiting the complications. The objectives of treatment include preserving length, coverage of the remaining stump with sensate skin, avoidance of painful neuromas, and maintaining the function of the proximal joints.  Optimal management of hand amputations results in the removal of irreparably damaged tissue, resolution of pain, and restoration of upper extremity function.[12] 

Complications

Complications threatening the viability of a replanted hand are most prevalent in the immediate postoperative period. These complications are often vascular in nature, with arterial thrombosis secondary to persistent vasospasm as the most common cause of replanting failure in the first 12 hours postoperatively. Several interventions are available to prevent catastrophic failure. Nonadherent dressings around the replant site should remain moist to avoid the drying of blood and wound drainage, which can result in the formation of a constricting circumferential tourniquet.[9] The risk of vasospasm is reduced by keeping the patient in a warm environment, ensuring adequate pain control, and restricting the intake of caffeine and tobacco products. Some advocate for the use of sedating medications to prevent anxiety-related vasospasm.[13]  

Anticoagulation is useful in the majority of patients following replantation.  While many options are available, there is currently no consensus protocol.[14] Dextran infusion is a frequent intervention to ensure adequate circulating volume and prevention of vascular stasis.  Aspirin is appropriate following an uneventful replant.  Intravenous heparin may be indicated postoperatively if there is an increased risk for thrombosis formation, such as in older patients, crush injuries, and where there were technical concerns with the surgical anastomosis.[15]  

Monitoring of the circulatory function is possible in a number of ways, including skin temperature, skin color, oxygen tension, and hydrogen dilution. Skin temperature is the most sensitive means of monitoring circulation.  A decrease of more than 2 degrees celsius within 1 hour or an absolute temperature of less than 30 degrees, in the replanted part, is indicative of a circulatory compromise. Decreased temperature, skin pallor, and loss of skin turgor may indicate loss of arterial inflow. Loosening of constricting bandages and placement of the hand in a dependent position are the first steps in managing arterial insufficiency. The next steps include the initiation of heparin therapy and the administration of a sympathetic block to the affected hand.[16]  If there is no restoration of arterial inflow, then return to the operating room for surgical re-anastomosis is warranted. A cyanotic, swollen hand indicates venous congestion. Elevation of the affected hand above the level of the heart may aid in the vascular outflow. Leech therapy can reduce venous congestion through the inhibition of thrombin, which occurs via hirudin release. There is a risk of Aeromonas hydrophila infection following leech application, which is preventable with the use of antibiotic prophylaxis.

The most common overall complication, affecting nearly all replant patients, is cold sensitivity.  Although it is rarely functionally limiting and improves with time, few patients experience complete resolution over the long term.[17]  Return of sensation is dependent on several factors but is most closely linked to injury mechanism.  Sharp injury mechanisms fare better than crush and avulsion-type injuries.[18] The prognosis for sensory recovery in children undergoing replantation procedures is better than that for adults. Unfortunately, only slightly more than half of all replantation patients have a return of useful two-point discrimination. Stiffness of the affected joints is also very common, often due to a combination of delayed therapy and scar tissue formation.[19] The success of the replant is measurable by the range of motion, grip strength, presence of sensation, and the ability to return to work.  Grip strength and DASH scores have correlations with each other, with DASH being a valid measure of replantation success as perceived by the patient.[20]

The complications and resulting prognosis following revision amputation of the hand are quite different from those of replantation.  Loss of forearm pronation and supination can occur with more proximal amputation. As with any amputation, neuroma formation is a concern and one that can be mitigated with purposeful surgical technique. Cosmesis is often a concern as well, particularly dependent upon the level of amputation and type of prosthesis. Revision amputation, particularly of the dominant hand, generally has a lower patient-reported quality of life outcome as compared to successful replantation.[21]

Clinical Significance

Nearly all acute hand amputations are the result of trauma.  Medical stabilization must be the first priority in the care of the patient with a hand amputation. Once stabilized, a timely evaluation and treatment plan is critical. The ultimate decision between replantation and revision amputation is dependant upon several factors, including injury mechanism and timing, access to care, medical comorbidities, and patient goals. No matter the treatment course, hand amputations are known to be devastating injuries with tremendous physical, emotional, and economic, and societal costs.

Enhancing Healthcare Team Outcomes

The successful management of hand amputations is only possible through an interprofessional approach during all phases of care.  Protocols must exist and be well-implemented at a systems-level in order to optimize patient outcomes.  It is the role of first-responders and emergency physicians to understand their roles in medical stabilization and timely referral to facilities that are equipped for these injuries.  An appreciation for the time-critical nature of replantation attempts is crucial.  Hand surgeons and their operating room teams must be efficient and prepared, as well as readily available, to optimize outcomes.  The final goal of any treatment, namely restoration of function, cannot be achieved without therapists and rehabilitation specialists who are knowledgeable and diligent in their care.  

To summarize, the optimal treatment of hand amputations requires an interprofessional approach involving first-responders, emergency department personnel, experienced surgical teams, and dedicated rehabilitation experts. [Level 4]