Lower-Extremity Amputations Technique

A multidisciplinary approach to treatment should be taken. ^{[7, 8]} Patients undergoing amputation should be evaluated for cognitive and physical abilities. Consultation with a physical therapist, social worker, and possibly a psychiatrist should be obtained to determine the patient's ambulatory potential. Allowing the patient to talk with someone who has undergone an amputation can also prepare the patient for future expectations and provide answers to questions the patient may not have considered.

Patients with peripheral vascular disease (PVD) should have an evaluation by a vascular surgeon to determine the feasibility of vascular reconstruction. Consultation with an internal medicine specialist is also recommended for evaluation of the patient's general medical health and any cardiovascular disease, as well as control of diabetes mellitus, if appropriate. Mortality after lower-extremity amputations in diabetic patients can be high. ^{[12, 29]} In addition, many patients with PVD are malnourished and may have additional cardiac or cerebral ischemic disease. Infections that develop in these patients are often polymicrobial, and broad-spectrum antibiotics are recommended in conjunction with wide debridement.

In clostridial myonecrosis infections, hyperbaric oxygen may be necessary in combination with the appropriate antibiotic treatment. Streptococcal myonecrosis requires appropriate antibiotic treatment and excision of the involved muscle compartment. This excision may make the amputation reconstructive difficult.

Great advances have been made in the treatment of severe lower-extremity trauma and PVD. Revascularization, internal fixation of fractures, microvascular techniques, and free tissue transfer procedures have improved and favorably enhanced the patient's outcome. Failure of these techniques when extensive efforts have been pursued may result in a negative patient outlook. Amputation may be viewed as a failure by both the surgeon and the patient. The patient may picture himself or herself as incomplete by societal standards. The current view is that amputation surgery is a reconstructive procedure intended to return a patient to an active life.

Compared with the changes that have taken place in the field of prosthetics, amputation techniques have changed little over the years. Even with a well-performed amputation and a well-fitted prosthesis, some patients have persistent symptoms of residual extremity pain, swelling, and a sense of instability, as well as have a decreased length of prosthetic wear. These patients pose a challenge for the reconstructive surgeon. The effects of previous surgery, altered anatomy, muscle and bone atrophy, and aerobic deconditioning are important variables in predicting the success of amputation surgery.

General principles for amputation surgery involve appropriate management of skin, bone, nerves, and vessels, as follows:

• The greatest skin length possible should be maintained for muscle coverage and a tension-free closure
• Muscle is placed over the cut end of bones via a myodesis (ie, muscle sutured through drill holes in bone), a long posterior flap sutured anteriorly, or a well-balanced myoplasty (ie, antagonistic muscle and fascia groups sutured together)
• Nerves are transected under tension, proximal to the cut end of bones in a scar- and tension-free environment, so as to reduce the chances that neuromas will form and be a source of pain; placing the cut nerves in a more proximal scar-free environment assists in decreasing potential irritation and pain; ligation of large nerves can be performed when an associated vessel is present
• The larger arteries and veins are dissected and separately ligated so as to prevent the development of arteriovenous fistulas and aneurysms
• Bony prominences around disarticulations are removed with a saw and filed smooth; diaphyseal transections can be covered with a local flexible osteoperiosteal graft; although maintaining the maximal extremity length possible is desirable, below-knee amputations are best performed 12.5-17.5 cm below the joint line for nonischemic limbs
• One application guide is to make a limb 2.5 cm long for every 30 cm of body height; for ischemic limbs, a higher level of 10-12.5 cm below the joint line is used because making limbs longer than this can interfere with prosthetic use and design ^[2]

Osteointegration has now been performed in multiple centers internationally. ^[30] This procedure, initially applied in dental surgery for tooth loss,  involves the use of a metal post, treated similarly to a total joint ingrowth prosthesis, secured to bone. Two main types of implant are currently available: screw-type and press-fit. ^[31] Success has been achieved in several settings; however, there remains a need for long-term data, and a significant potential for postoperative infection and osteomyelitis has been reported. Osteointegrated implants may also be subject to metal fatigue that leads to septic loosening and stem breakage. ^[32]  

Lower-limb reconstruction with a quad flap (consisting of parascapular, scapular, serratus, and latissimus dorsi free flaps combined on a single pedicle) has been described. ^[33]

Tourniquets are used on a discretionary basis in patients with vascular disease. ^[34] The extremity is prepared in a standard fashion. The skin incision is made as distal as is feasible, and dorsal and plantar flaps are created. Attention should be paid to ensuring viable margins so as to minimize the risk of subsequent osteomyelitis. ^[35] The flexor and extensor muscle groups are elevated as one musculofascial flap. The vessels are isolated and ligated, and the digital nerves are separated, distracted, and ligated at a more proximal level.

Osteoperiosteal flaps are elevated from the first and fifth metatarsals. The metatarsals are transected from dorsal to plantar at approximately 15º, with a cascade of shortening as one proceeds laterally. Care is taken to smooth off any rough borders with a file and to not leave any significant prominence beneath the skin. The osteoperiosteal flaps are sutured end-to-end and to each metatarsal, covering (closing) the exposed diaphysis. The flexor and extensor groups are sutured to each other through the fascial attachments, forming the myoplasty.

If used, the tourniquet is released and bleeding is controlled. The skin is contoured to the underlying myoplasty, allowing for a smooth transition. Penrose drains are placed for hematoma decompression. Sterile dressings and a well-padded posterior splint are applied.

The splint is removed after 2-7 days. Physical therapy is also instituted for patient education on transfers, desensitization of the residual extremity, aerobic conditioning, and upper-body strengthening. Full weightbearing is initiated at 4-6 weeks or pending wound healing.

Informed consent is obtained from all patients. In patients in whom a very short residual limb is expected, the possibility of knee disarticulation or amputation above the knee is also discussed. Every attempt is made to maintain the knee joint. The patient is positioned supine. A bump under the hip may be used to control rotation of the limb, and a tourniquet is applied. In patients with vascular disease, tourniquet use is on a discretionary basis. After preparing and draping of the extremity, previous incisions are used, if appropriate. No differences in wound healing between anterior-posterior, oblique, and medial-lateral incisions have been reported.

After incision, dissection is carried down to the muscular layer, then carried more proximally, with the anterior, lateral, and posterior compartments identified and isolated. If a long posterior muscle flap was used for anterior coverage in the primary amputation, care should be taken to preserve the length of this posterior muscle compartment. During isolation of the muscle compartments, care should also be taken to maintain the fascial attachments to the musculature for later myoplastic reconstruction.

After isolation of the muscle compartments, the main neurovascular structures are identified, released from scar tissue, and separated. This should include the tibial nerve, artery, and vein; the superficial and deep peroneal nerves and the peroneal artery and vein; the sural nerve; and the saphenous nerve and vein. The identified nerve should be transected as high as possible and allowed to retract into the soft-tissue bed. The artery and nerve are separated and ligated in a separate fashion.

Once soft-tissue dissection is completed, attention is turned to the osseous structures. The periosteum is incised from anterior to posterior on the fibula and tibia. With a 45° chisel, an osteoperiosteal flap is elevated medially and laterally in such a way as to maintain the proximal attachment. Small cortical fragments are left attached to the periosteum.

Once the osteoperiosteal flaps are created, any exposed cortical bone that remains is resected to the same level, thereby facilitating the suturing of the osteoperiosteal flaps. This requires no more than 1.5-2 cm of bone to be resected. The medial tibial flap is sutured to the lateral fibular flap, and the lateral tibial flap is sutured to the medial fibular flap, resulting in a tubelike structure.

In short or very short residual extremities, free osteoperiosteal grafts are harvested from the proximal tibia, contralateral extremity, or iliac crest to maintain bony length. This may also be performed on any length of residual extremity. The authors have used free osteoperiosteal grafts harvested from the removed limb in primary amputations without difficulty and with complete synostosis formation.

Some short transtibial extremities exhibit abduction of the fibula (abducted fibula) secondary to the pull of the biceps femoris. This may lead to a lateral pressure point and prosthetic difficulties. The fibula is reduced into an adducted position and a lag screw placed into the proximal tibiofibular joint, stabilizing this dynamic deformity with or without an arthrodesis of this joint.

The mobilized musculature is then brought distally, covering the osteoperiosteal bridge, and a myoplasty is completed, suturing the posterior musculature to the anterior and lateral musculature. (If there is a length discrepancy, then a myodesis can be performed.) However, the goal is to provide soft-tissue coverage for the distal aspect of the residual extremity.

The Ertl technique, an osteomyoplastic transtibial amputation procedure that involves forming a tibiofibular bone bridge to provide a stable tibiofibular articulation that may be capable of some distal weightbearing, may be used to create a highly functional residual limb. ^[36] Further study is needed to define patient selection, technical details, and postoperative care for this technique.

After the completion of the myoplasty, the skin is mobilized over the underlying myoplasty. Care is taken to reapproximate the skin in a symmetric fashion, leaving neither "dog ears" nor crevices. Drains are placed to prevent hematoma formation. After sterile dressings are applied, the extremity is placed in a plaster splint in extension. The splint is removed after 2-7 days.

The use of a temporary total-contact end-bearing prosthesis is begun after 5-8 weeks. Physical therapy is also instituted for patient education on transfers, desensitization of the residual extremity, aerobic conditioning, and upper-body strengthening.

The patient is informed of the surgical risks and complications. All attempts are made to maintain residual extremity length to avoid the necessity of increased energy expenditure. In secondary reconstructive cases, the previous operative report should be reviewed and attention directed toward treatment of the muscles and nerves, which may assist in the exposure and dissection.

The extremity is prepared in a standard fashion. A tourniquet may not always be feasible, and a sterile tourniquet may be used. A bump is placed under the hip of the involved extremity to assist with rotational control. The previous incisions are identified and used, if appropriate.

Dissection is carried to the muscular layer. The muscles are often retracted and atrophic, necessitating proximal dissection and muscle identification. The adductors, abductors, quadriceps, and hamstrings are isolated in their respective groups. The fascial envelope is maintained for subsequent myoplasty. The neurovascular structures are identified and separately isolated. Separating the nerve from the artery is important. In this manner, pulsatile irritation of the nerve is avoided.

The nerve trunk is mobilized by blunt dissection and distracted and transected at a higher level, which allows retraction into the soft-tissue surroundings. If a tourniquet has been used, it may be released to evaluate bleeding. The vascular structures are often friable and must be handled carefully to avoid proximal retraction. The artery and associated veins are separately ligated to avoid arteriovenous connections.

Attention is directed toward the distal residual femur. The periosteum is incised from anterior to posterior. With a 45° osteotome, medial and lateral osteoperiosteal flaps are elevated, with their proximal attachments maintained. Elevation of the flaps is aided by rotating the chisel 180°, lifting and maintaining the osteoperiosteal attachments. The femur is transected at the level of the osteoperiosteal flaps, with minimal femur necessitating removal. The medial and lateral flaps are sutured together, and circumferential periosteal sutures are placed, occluding the end of the open medullary canal.

An alternative method is to prepare a longer medial- or lateral-based osteoperiosteal flap, securing it to the opposing and circumferential periosteum, achieving medullary coverage.

Myoplasty is performed by suturing the antagonistic muscle groups to each other and anchoring them into the periosteum, covering the osteoplasty. The adductors are sutured to the abductor group first, or they are anchored to the lateral femoral periosteum. The abductors are imbricated over the adductor attachment and additionally secured to the periosteum, anteriorly and posteriorly. The flexors are sutured to the extensor group and the underlying adductor/abductor groups, centralizing the distal femur in a muscular envelope.

The skin is fastened to the underlying myoplasty in a symmetric fashion, with care taken to avoid dog ears and invaginations of the incision. A smooth contour is the goal, allowing a better limb-prosthesis interface. Penrose drains are placed before the closure is completed.

Postoperatively, the residual extremity is placed in an Ace wrap hip spica or a bulky plaster splint, depending on the length. Sutures are removed after 2-3 weeks, depending on wound healing. A temporary total-contact end-bearing prosthetic fitting is coordinated with the patient's prosthetist 5-8 weeks postoperatively. Physical therapy is initiated for transfers, desensitization, range of motion, aerobic conditioning, and upper-body strengthening.

Postoperative dressings and treatments vary, each with advantages and disadvantages. There are four generic types of postoperative dressings available, as follows:

• Soft dressings - These dressings do not control postoperative edema
• Soft dressings with pressure wrap - These dressings require an even distribution of pressure to avoid possible limb strangulation
• Semirigid dressings - These include plaster splints and Unna Paste Bandages held in place with a stockinette; they have the same advantages that rigid dressings do, except that no immediate postoperative prosthesis can be used
• Rigid dressings - Many such dressings are commercially available, and intraoperative prosthetic assistance may be required; potential advantages include residual extremity maturation, decreased edema, less pain, wound protection, and early mobilization in combination with an immediate postoperative prosthesis; disadvantages include poor access to the wound and excessive pressure, leading to wound necrosis

Physical therapy for transfers and assisted ambulation are initiated. Assisted ambulation is at the discretion of the surgeon and therapist, depending on the patient's rehabilitation potential. Precautionary instructions regarding falling are provided to the patient to avoid the potential of injuring and opening the postoperative wound.

A consultation should be obtained for psychosocial and emotional issues. Support groups for people who have undergone amputations and discussion with someone who has undergone amputation are of assistance. ^{[7, 8]}

Incorporated into the preoperative and operative plan are (1) careful handling of tissues and (2) reconstruction of the limb to the best anatomic and physiologic condition possible, in hopes of avoiding known complications. Common complications include the following:

• Wound breakdown and skin problems
• Swelling
• Edema
• Joint contractures
• Pain
• Phantom limb sensation

Wound healing in the patient with vascular disease can be severely compromised by the patient's underlying disease or by skin closure under tension. Small areas of wound breakdown should be allowed to demarcate, and these can be treated with open or wedge resection. Larger areas with exposed muscle and bone may necessitate revision of the amputation, shortening of the bone, and closure without tension.

Skin difficulties are encountered between the residual limb and socket interface and can usually be avoided with good hygiene. The socket liner should be cleaned regularly and kept dry and free of topical soap residues.

The use of incisional negative-pressure wound therapy (iNPWT) may help reduce incisional complications after nontraumatic lower-extremity amputations. ^[37]

Folliculitis of the residual limb can be avoided by not shaving. When folliculitis is present, it can be treated with oral antibiotics. Similarly, hidradenitis should be managed with appropriate hygiene and occasional oral antibiotics.

Postoperative edema may occur and further compromise wound healing. This problem can be minimized by performing medullary canal closure and myoplasty. Postoperative bulbous swelling of the distal residual extremity is due to tight proximal dressings. This may lead to congestion and subsequent wound and prosthetic-fitting difficulties. Similarly, if the prosthesis is too tight proximally, bulbous swelling and venous congestion occur and may lead to cellulitis.

Persistent residual extremity swelling after maturation is most often due to a poor prosthetic fit or medical problems. Chronic swelling without treatment may lead to verrucous hyperplasia. Treatment consists of a total-contact socket with frequent alterations as needed to accommodate volume changes.

Joint contractures of the hip or knee may occur at the time of surgery or postoperatively from lack of activity and prolonged sitting or wheelchair ambulation. At the time of surgery, overtightening of the muscles should be avoided and appropriate postoperative positioning maintained.

In patients who have undergone transtibial and transfemoral amputations, prolonged sitting with the hip and knee flexed should be avoided. Patients who have undergone transfemoral amputations should be instructed to lie in the prone position multiple times during the day to stretch the hip musculature. Physical therapy should be initiated for early range-of-motion instructions. When present, joint contractures can make prosthetic fitting and wear very difficult. Dynasplint treatment may help in achieving residual limb extension.

Phantom limb sensation (ie, the sensation that the amputated limb is still present) occurs in nearly all patients who undergo amputations. It tends to decrease gradually over time. Phantom limb pain is described as a painful burning sensation in the amputated limb, and it is more common than was previously thought. Contributing causes of residual limb pain include neuromas at the level of the amputation, which become adherent to skin, muscle, and bone. This can lead to direct nerve-end stimulation or pain from traction with extremity motion. Continuous pulsatile arterial stimulation of the nerve occurs when the neurovascular structures are ligated together.

In patients who have undergone transtibial amputations, nerve stimulation can occur from compression of the nerve between the mobile fibula against the tibia. Additional causes of pain include the following:

• Incompetent soft-tissue envelope
• Prominent bone ends and spurs with associated bursitis
• Deep tissue scarring
• Ischemia in patients with vascular disease

Noninvasive treatment modalities may be tried initially, such as desensitization therapy, progressive and continued prosthetic wear, intermittent compression, medications, transcutaneous nerve stimulation, or a trial of proximal nerve blocks. Reconstructive surgery is often necessary to remove the neuromas and place them in an area free of scarring and adhesions and to reorganize the tissues to the most anatomic position possible through osteomyoplasty.

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) procedures can improve patient-reported outcomes for the treatment of symptomatic neuromas after amputation. Hoyt et al, in a study aimed at determining what nerves most often required secondary pain intervention such as TMR or RPNI after conventional amputation, found that for symptomatic neuromas above the knee, the sciatic nerve was most likely to require intervention, whereas after transtibial amputation, the tibial nerve and the common or superficial peroneal nerve were most problematic. ^[38]

Depressive symptoms may develop after dysvascular amputation. ^[39]

A study (N = 4162) using data from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database identified the following predisposing factors for four complications after leg amputation ^[40] :

• Surgical infection - Preoperative open, contaminated, or dirty/infected wounds; longer intraoperative times; development of sepsis prior to surgery; admission of patients from home or another hospital
• Additional service - Preoperative open, infected, or dirty/infected wounds; height; weight; total length of hospital stay; ethnicity
• Deep vein thrombosis (DVT) - Preoperative congestive heart failure; large decreases in body weight; total length of hospital stay
• Sepsis - Preoperative functional heath status; total length of hospital stay; amputations conducted as emergency cases; preoperative acute renal failure; open or infected wounds; sepsis; contaminated or dirty/infected wounds

In osteointegrated implants, metal fatigue may occur, leading to septic loosening and stem breakage. A study by Mohamed et al found that possible risk factors for this kind of implant failure included a small stem diameter and a high number of infectious events. ^[32] Accordingly, the authors recommended avoiding a small stem diameter in patients undergoing a lower-limb amputation with a CoCrMb osseointegrated implant. Further research with longer follow-up is needed.