Despite best intentions and modern technology, severe limb trauma can often result in a catastrophic outcome. The decision to salvage or amputate the injured limb has generated much controversy in the literature, with studies supporting each approach. Various scoring systems have proven unreliable in predicting the need for amputation or salvage. A team approach with differing specialties, including orthopaedic, plastic, vascular, general trauma, and rehabilitation, is recommended for treating patients with a mangled extremity.
In traumatic amputations, a poor soft tissue envelope often characterizes the limb, and there may be more serious systemic injuries or comorbidities that shape the treatment plan. Wound treatment starts at the first encounter, with appropriate dressing materials that may include negative pressure wound therapy, and is guided by the tenets of a reconstructive ladder algorithm. The zone of injury can be dynamic throughout the treatment period. During the initial injury and subsequent surgeries, vital signs and hemoglobin/hematocrit levels should be monitored because they are of great importance in ensuring adequate perfusion of a compromised soft tissue envelope. Tourniquet use should also be avoided, and surgeons should work closely with anesthesia during the procedures to maintain adequate perfusion.1 But despite these improved processes, problems often arise that necessitate or complicate amputation. Outcomes can therefore be fraught with complications.
MANAGEMENT OF THE BONE
The level of amputation is dependent on the soft tissue injury, the skin, the zone of injury, and the patient. If an external fixator has been used for temporary stabilization, external fixator pin sites may change the level. The ideal length for transtibial amputations is 2.5 cm of bone length for each 30 cm of body height (range, 12.5–17.5 cm), with posterior skin flaps of gastrocnemius and soleus muscles. For transfemoral amputations, the ideal length is 9–14.5 cm proximal to the knee, with long posterior skin flaps.2 However, management of the amputation with modern devices is actually quite adjustable and can be discussed with the prosthetics team if there is any debate with regard to length issues in very short or tall patients.
MANAGEMENT OF THE SOFT TISSUE
Debridement should be maximized to minimize the number of surgeries. Dead tissue is nonbleeding, with clotted vessels or nonviable dermis. Debridement can also be important for debulking to prepare for the next case. At the final surgery, this means separating the fascial plane between the soft tissue and the skin because skin will need to be mobilized for closure. It is important to protect a blood supply to both deep and superficial debridement planes.
Careful nerve management is crucial to minimizing the chances of phantom pain. It is important to identify the nerves individually, apply gentle traction, sharply transect them as proximally as possible, and allow them to retract (see Figure, Supplemental Digital Content 1, https://links.lww.com/BOT/A550). Cautery may be used on the nerve before retraction is allowed. The mechanism of injury may also contribute to the phantom pain; however, the exact etiology is unclear.3 Patients with a twisting mechanism or incomplete amputation at the time of injury may have an increased risk of phantom pain. There are different medications available for phantom pain, and they should be started as needed in consultation with psychologists and rehabilitative physicians. For management of the vessels, everything retained proximal to the amputation level should receive 2 ties and a clip to ensure that there will not be bleeding.
Muscle is retractile, and thus, a more distal resection than bone is necessary for closure while still ensuring adequate vascular supply at the chosen level. In the transtibial amputation, a myodesis of the superficial posterior compartment muscles is important for a stable cover of the bone remnant. The deep posterior muscle group is cut at the level of the bone resection. The muscles of the anterior or lateral compartment can be approximated with a portion of the posterior compartment to cover the anterior portion of the bone, resulting in a nice residual limb. Myoplasty allows for a balanced soft tissue envelope. Likewise in the femur, it is important that the adductors undergo myodesis and can balance the remaining quadriceps and hamstrings (see Figure, Supplemental Digital Content 2, https://links.lww.com/BOT/A551). For those patients who undergo a through-knee amputation, the patellar tendon and cruciate ligament can be joined. When completing through-knee amputations, the meniscus is kept in place until the final closure. After removal of the meniscus, the remaining femoral condyle cartilage surfaces will have minimal damage. Flattening of the femoral condyles is not recommended as that can lead to heterotopic bone formation in response to the resection and interfere with prosthetic fitting.
MANAGEMENT OF THE SKIN
“Training the skin” is an important concept. The skin that is on the medial ankle might be covering the lateral aspect of the leg at the final closure. With subsequent debridement, the skin should be placed in the new final closure position to determine if it is ready for closure. It is better to have too much skin from the time of an initial amputation. A full-thickness skin flap is desired for closure. At the final closure, the sutures are tensioned simultaneously to minimize local soft tissue tension, and the sutures are left in for an extended period—approximately 4 weeks. The patient participates in rehabilitation and begins lifting the leg early. If the sutures are removed too early, movement of the residual limb will place tension on the wound. If needed, although not ideal, skin grafts can be used on or around the stump (see Figure, Supplemental Digital Content 3, https://links.lww.com/BOT/A552). Soft tissue coverage should be planned appropriately so that as much native skin as possible will be on the weight-bearing portion of the residual limb. If more skin is required for closure in a transtibial amputation, removal of the fibula can yield additional skin.
POSTOPERATIVE MANAGEMENT OF THE RESIDUAL LIMB
After surgery, on postoperative day 2, patients are placed in a shrinker and a protector. The protector (an articulated knee brace with a hard cap over the end of the amputation for a transtibial amputation) prevents contracture and protects the residual limb from a fall. Falls can lead to complications. More than 50% of lower extremity amputees fall in the first year, potentially affect healing time.4 It is important that the patient not be fitted in their final prosthesis until the skin is completely healed. If early blisters form or areas remain moist, a silver-impregnated dressing can be used to absorb several times its weight in moisture and provide an antibacterial environment. To toughen the skin, benzoin can be applied daily. If patients are unable to find benzoin, a clear nail polish reapplied every few days is a good substitute because it will peel off naturally when the skin is ready for prosthetic fitting. When ambient temperature is high, medicated ointment can be used along with special antiperspirant sprays. In cold weather, maintaining the moistness of the limb to prevent any raw areas can be accomplished through the use of good lotion. It is recommended that the amputee only wash the residual limb once daily so as not to rob the skin of natural oils. Once their prosthesis is in place, the patient should complete physical therapy at a facility for amputees. It is important that the surgeon and the prosthetist educate the patient for residual limb management.
WHICH PROSTHETIC DEVICE IS NEEDED?
In the past 2 decades, advances in technology have resulted in prosthetic devices with leading edge componentry, allowing patients many functional opportunities. Conversely, although conventional prostheses provide a means for ambulation after limb loss, they have limitations in restoring normal mobility. These limitations include the following: difficulty traversing stairs and ramps; abnormal gait patterns with asymmetric biomechanics, resulting in balance deficits; and ultimately, falls or the fear of falling, which often relegates patients to life in a wheelchair for safety reasons.4 Advances in technology have allowed people with limb loss to return to more normal walking on stairs and ramps and to participate in various sporting and water activities—often unattainable by conventional prosthetic users. These same technological advances have provided amputees with safer mobility, including fewer falls and decreased compensatory complications, such as back pain and skin breakdown. Evidence shows that when amputees use advanced microprocessor components, they fall less or experience less frequent near-falls, reducing the risk of fractures, ligament injuries, and head injuries.5 Microprocessor components have also been shown to reduce impact to the contralateral limb, which is at an increased risk for developing osteoarthritis due to the biomechanical compensatory forces resulting from abnormal gait patterns in prosthetic use. These computerized components reduce pressure in the socket, thereby preventing skin breakdown and ulcers and suggesting that wound care or revision surgery of the residual limb could be significantly decreased.
Evidence also shows that users of microprocessor components felt safer while walking and walked more like their able-bodied peers when compared with users of conventional components. Objective kinematic measurements confirm this, showing that patients demonstrate gait patterns more similar to physiologic able-bodied gait patterns.6,76,7 Restoring preamputation activity levels can be a challenge for amputees; however, activity-specific prostheses can help to minimize this gap for sporting activities.
Leading edge components typically trickle down from the military, as the Department of Defense and research-based projects become available to civilians. But many consider the cost of sophisticated prostheses to insurance carriers and Medicare unsustainable. The grassroots efforts of the Amputee Coalition focused on Prosthetic Parity, requiring insurance companies to provide what Medicare provides patients. Today, the entire system is being challenged, and many attribute this to the soaring costs of prosthetic components (see Figure, Supplemental Digital Content 4, https://links.lww.com/BOT/A553).
On the other end of the spectrum, disaster relief for amputees in places, such as Cambodia or Haiti, highlight the need for affordable and sustainable options for basic prosthetic devices in developing countries. One of these inexpensive solutions is a plastic prosthesis created for the International Committee of the Red Cross that costs less than $300 to make. When compared with the most expensive commercially available microprocessor prosthesis, the cost differential is more than 400 times greater. Not surprisingly, serious discussions for the sustainability of the soaring costs of prosthetic devices are at the forefront of the health care system.
LATE COMPLICATIONS: HETEROTOPIC OSSIFICATION
Heterotopic ossification (HO), or the pathologic formation of mature lamellar bone in soft tissue, occurs after mangled extremity trauma, blast injuries, burns, spinal cord injuries, traumatic brain injuries, acetabular fractures, elbow fractures, and elective procedures such as total hip arthroplasty. The radiographic appearance may contain both cortical and cancellous bone that can be confluent with the adjacent skeleton. HO matures from the periphery to the center, and its histologic appearance of woven and lamellar bone is identical to normal bone. Potter et al8 reported a 63% incidence of HO in the residual limbs of current combat-related amputees. Eighty percent of the amputations performed within the zone of injury in blast injuries developed HO. None formed in nonblast injuries amputated outside the zone of injury. Although HO in residual limbs can be managed with prosthetic modification, 6.7% of patients required excision of HO. Predictive factors for the development of HO after an orthopaedic procedure in combat-wounded patients were younger than 30 years of age, an amputated limb, multiple injured extremities, and an injury severity score of >16.9 Patients who developed HO had more severe soft tissue injuries, requiring more debridement and longer negative-pressure dressing therapy.
BASIC SCIENCE AND PATHOPHYSIOLOGY OF HO
Injured adult muscle contains pluripotent mesenchymal stem cells in the vasculature that are capable of differentiating into chondroblasts or osteoblasts and thus does not require stem cells from the bone itself to generate HO.10 Under conditions of inflammation, trauma, venous stasis, and tissue hypoxia, growth factors are induced that drive the differentiation of these cells. Interleukin-6, the most potent marker and stimulant of mesenchymal stem cell differentiation to osteoblast lineage,11 is elevated in the serum of patients with high-energy combat injuries. In the serum of patients with severe traumatic brain injuries, there was a significant increase in the rate of proliferation and differentiation of skeletal muscle cells into osteoblastic cell lines in comparison with serum from those with long-bone fractures, and controls manifested by an increased osterix, alkaline phosphatase, and mineralized nodules within the mesenchymal cells in the culture.12
Genetics may also have a role in the development of HO because there may be an association with HLA-B27. One polymorphism of the beta-2-adrenergic receptor gene was associated with an increased risk of HO, whereas a polymorphism of toll-like receptor 4 and complement factor H were associated with a decreased risk.13 Previous HO formation also seems to be a risk for future development. Other risk factors include male gender, hypertrophic osteoarthritis with prominent osteophyte formation, ankylosing spondylitis, and diffuse idiopathic spinal hyperostosis. Complete neurologic injury, thoracic-level deficits, spasticity, tracheostomy, and pneumonia all place a patient at an increased risk of developing HO.14
PREVENTION OF HO
The prevention of HO starts when planning surgery. Any damaged muscle encountered should be excised. The influence of timing of the surgical intervention on HO formation is unclear. Some have reported that delayed intervention results in a higher rate of HO formation, but this may have been related to fracture severity instead of delay.9 In acetabular fractures treated with total hip arthroplasty, early intervention within 2 months of injury was associated with more frequent significant HO compared with late intervention occurring after 1 year.15 Prophylactic treatment to prevent HO formation may be provided pharmacologically or by low-dose irradiation. A single dose of irradiation therapy (x-ray therapy) of 7–10 Gy within a window of 24 hours preoperatively to 72 hours postoperatively is effective in the prevention of HO formation. A systematic review of the prophylaxis after fixation of acetabular fractures found a lower percentage of HO in patients treated with x-ray therapy compared with indomethacin.16 A prospective, randomized, placebo-controlled, double-blinded trial of indomethacin corroborated the 63% compliance rate previously established. Interestingly, these investigators found an increased incidence in computed tomography–proven nonunions of the posterior wall associated with 6 weeks of indomethacin use, but clinical significance was not determined.17
EXCISION OF HO
The excision of HO is indicated when patients experience a mechanical block to motion, ankylosis, or bony prominences resulting in an overlying ulcer or discomfort. The decision to excise relies on the maturity of the HO, fracture healing, spasticity, patient compliance with therapy, and the surrounding soft tissue envelope including any skin grafts or flaps. Recurrence in head injured patients may be nearly 20%. However, early excision does not necessarily result in more frequent recurrence.18 The current trend is earlier intervention to benefit recovery with less disuse osteopenia and atrophy. In cases of HO formation within amputations, the first line of treatment is prosthetic modification to avoid prominences.
Successful management of the residual limb can only occur with a team in place that includes prosthetists, who meet the patient and their family before the amputation if possible, and answer questions and review the expected recovery and prosthetic fitting. Previous amputees are a great resource for anxious patients and their families. The patient should be provided with realistic expectations of the life changes they will be expected to encounter. Residual limb management with a team approach can lead to a successful outcome. In rehabilitation, functional goals may determine the choice of prosthetic components: basic or advanced. The desired outcome is to restore function, allowing patients to achieve personal goals, regardless of prosthetic cost.
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