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Amputations of the Upper and Lower Extremities

Surgery
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Introduction

Severe injuries involving the upper and lower extremities are common in the civilian sector and are most frequently incurred in the setting of motor vehicle accidents or industrial accidents.[1]
In the setting of military conflicts, extremity injuries have been witnessed with increasing frequency in soldiers over the past two decades. This uptick in extremity trauma has, ironically, been attributed to significant improvements in body armor and head protection that has enabled soldiers to survive formerly mortal assaults, but has left them with upper and lower limb trauma due to relative under-protection of these areas.[2]
The increasing utilization of improvised explosive devices (IEDs), in particular, has resulted in a marked increase in combat-related upper and lower extremity injuries that ultimately require amputation. Knowledge of core concepts regarding limb amputation is therefore gaining increasing importance in the management of war-related injuries, whether they be to soldiers or collaterally wounded civilians.

Indications for Extremity Amputation

Historically, extremity amputation has been regarded as a last resort for management of a compromised limb in which attempts at salvage are considered to be:
  1. futile due to the extent of limb compromise;
    or
  2. impossible due to patient instability/noncompliance and/or limited healthcare resources.
More recently, this notion has been revisited in the context of an increasing emphasis on treating amputation as a reconstructive procedure, rather than a surgical failure[3]; however, a full treatment of this philosophical shift is beyond the scope of this chapter.
In general, extremity amputation is indicated when one or more of the following circumstances is present in an injured limb, and when these circumstances are deemed to be irreversible:
  • Skeletal destabilization: Highly comminuted and/or multilevel fractures, frank bone loss, loss of ligamentous integrity
  • Loss of soft tissue coverage: Extensive compromise of skin envelope
  • Vascular insufficiency: Arterial or venous discontinuity, frank loss of vascular tree, extensive vascular thrombosis
  • Sensory impairment: Loss of protective sensation to high-traffic interface surfaces (e.g., palm of hand, sole of foot)
  • Motor impairment: Severe muscle mass compromise and/or loss, extensive tendon compromise and/or loss, large-scale loss of motor innervation
  • Neuropathic pain: Chronic regional pain syndrome (CRPS) and related limb pain conditions
For the purposes of this chapter, it is assumed that the etiology of such circumstances is trauma; however, it should be noted that similar circumstances may arise in the setting of infection, oncologic processes, congenital abnormalities and as a consequence of a variety of medical conditions.

Goals of Extremity Amputation

For over two thousand years, the primary goal of extremity amputation has been to provide an individual with a well-padded, stable residual limb. With the introduction of limb prostheses over the past few centuries, an additional goal has been to offer an appropriate platform for interfacing with a socket and terminal device. Over the past decade, increasingly sophisticated approaches to limb restoration have further expanded the goals of extremity amputation to include optimization of volitional motor control, provision of natural sensation and preservation of proprioceptive feedback.[4]

Initial Management

In the setting of trauma, initial management of severe extremity injuries must consider the overall condition of the patient. When gross patient instability precludes the possibility of attempts at limb salvage, acute amputation may be warranted to diminish further metabolic strain due to ischemic soft tissue burden; in such a circumstance, guillotine amputation at the level of most proximal gross limb compromise should be performed in conjunction with temporary soft tissue closure versus application of wet to dry gauze dressings.
Intravenous antibiotic therapy should be initiated and, once relative patient stabilization has been achieved, serial debridement of the injured limb should be performed every 1-2 days until the extent of tissue compromise has been fully evidenced and gross tissue decontamination has been achieved.
When available, negative pressure wound therapy (NPWT) may be a useful adjunct to enhance the recovery of marginal tissues and debride open wound sites during this phase of care.
Once full declaration of tissue viability has occurred and a determination of non-salvageability has been made, definitive limb amputation can then be reliably undertaken.

General Surgical Principles

Amputation procedures are optimally performed under sterile conditions and general anesthesia. When possible, placement of local anesthetic infusion pain catheters in the preoperative setting will greatly assist with postoperative pain management; under austere conditions, however, such adjunctive care may not be available, and liberal use of injected local anesthetic at the amputation site (while honoring toxic dose limits) may be substituted. Preoperative intravenous antibiotics are recommended for amputations at all levels. When anatomically feasible, amputation procedures should be performed under tourniquet control in order to limit excessive blood loss; in the case of high-level transhumeral or transfemoral amputations, this may not be possible.
Determination of optimal residual limb length requires careful consideration. First and foremost, the limb should be shortened to a level at which stable coverage of the terminus can be achieved. If the condition of the injured limb will permit some discretion regarding length determination, consideration must then be given to:
  1. whether the patient will have access to a limb prosthesis;
    and
  2. whether he or she is likely to use it. If the answer to this is no, efforts should be made to preserve as much limb length as possible, since maximal length of the residuum in this circumstance will augment its ability to be used as an assist and/or lever.
Alternately, if the answer to this is yes, then the length of the residuum must consider the minimum amount of room (i.e., device stack height) required to fit a prosthesis at a level that matches the joint position(s) of the (presumably intact) contralateral limb. Specific considerations for limb length by amputation level are discussed below.
Osteotomies performed at the selected amputation level are typically performed by a powered oscillating saw with copious irrigation in order to limit excessive heat transfer, but may also be performed by a hand saw or Gigli saw under controlled conditions. Smoothing of the distal bone ends with a rasp or burr should follow gross osteotomies to limit unwanted bony prominences.
Appropriate muscle stabilization over the distal residual limb is critical to avoid downstream issues with soft tissue subluxation, which can result in residual limb pain, distal ulceration and socket intolerance. This is best performed via a combination of both myodesis (i.e., coaptation of muscle to bone) and myoplasty (i.e., coaptation of muscle to muscle). Again, specific recommendations by amputation level are discussed below.
Closure of the skin envelope at the amputation site should include meticulous attention to limiting contour irregularities and/or folds. The ideal residual limb has a smooth, symmetric shape to enable optimal limb hygiene and socket fitting. Wound edges should approximate under mild to moderate tension at the time of closure so as to limit significant soft tissue excess following resolution of postoperative extremity edema, but should not be set at such high tension that wound edge ischemia results.
A three-layered suture closure is generally recommended, including approximation of Scarpa’s fascia with 2-0 or 3-0 vicryl sutures, followed by intradermal layer closure with 3-0 monocryl sutures and epidermal closure via 3-0 or 4-0 nylon interrupted percutaneous sutures. Closure over a 15- or 19-French Jackson Pratt or Blake drain is recommended, as well.

Specific Surgical Considerations by Amputation Level

Transtibial Amputation (TTA)
TTA should invariably be performed under tourniquet control. The optimal tibial osteotomy level is generally 12-14cm distal to the tibial plateau; this length typically provides ample limb length for prosthesis fitting while allowing for adequate soft tissue padding from a well-designed posterior flap. The anterior skin incision should be designed approximately 2cm distal to the planned tibial osteotomy level, and should then be curved posteriorly to include a broadly based posterior flap extending, if possible, to the distal Achilles.
The musculature of the anterior and lateral compartments should be shortened to the level of the tibial osteotomy. The posterior flap should be elevated from the superficial posterior compartment musculature including the muscle fascia; inclusion of this fascial layer provides additional structural integrity and augments the vascularity of the posterior flap. The gastrocnemius-soleus complex (GCS) should then be transected at the level of the mid-Achilles.
The deep posterior compartment musculature may then be shortened to the level of the tibial osteotomy. The tibial and fibular osteotomies should then be performed, with the fibula being shortened approximate 1cm more proximally than the tibia. Myodesis of the GCS to the anterior surface of the tibia can then be performed either with the assistance of unicortical suture anchors or bicortical osseous sutures (ideally 0 Ethibond or Fiberwire); this myodesis should be further supported by myoplasty of the GSC to the surrounding shortened musculature. A meticulous layered closure should then follow.
Transfemoral Amputation (TFA)
TFA should ideally be performed under tourniquet control; depending on the proximity of the amputation level, however, this may not always be feasible. The optimal femoral osteotomy level is approximately 12-14cm proximal to the distal ends of the femoral condyles.
A fishmouth incision is recommended, oriented so as to establish anterior and posterior skin flaps. Transection of the quadriceps, hamstring and adductor musculature should be performed approximately 3cm distal to the planned osteotomy level. Myodeses of the quadriceps and hamstrings are critical, and may either be performed with the assistance of unicortical suture anchors or bicortical osseous sutures (ideally 0 Ethibond or Fiberwire), followed by myoplasty. A meticulous layered closure should then follow.
Transradial Amputation (TRA)
As with TTA, TRA should invariably be performed under tourniquet control. The optimal level of TRA is somewhat controversial; unlike lower extremity amputations – in which expected loadbearing demands adequate distal padding – upper extremity amputations only require sufficient soft tissue coverage to avoid bony exposure and prominence.
In general, therefore, it is thought that TRA length should be maximized to whatever level provides stable distal soft tissue coverage. A fishmouth incision is recommended, oriented so as to create volar and dorsal skin flaps. Transection of the extrinsic flexor and extensor muscle groups should be performed approximately 2cm distal to the planned osteotomy level; this may be at the tendon level for many muscles, depending on the level of amputation.
Analogous to the fibula and tibia in TTA, osteotomy of the ulna should be performed approximately 1cm proximal to the level of the radial osteotomy. Myodeses of the flexors and extensors to the radius and ulna may then be performed using unicortical suture anchors or bicortical transosseous sutures (ideally 2-0 or 3-0 Ethibond or Fiberwire), followed by myoplasty. A meticulous layered closure should then follow.
Transhumeral Amputation (THA)
As with TFA, THA should ideally be performed under tourniquet control, but may not be feasible depending on the level of amputation. The optimal level of THA, like TRA, is somewhat controversial, but should generally be performed approximately 4-5cm proximal to the distal ends of the humeral condyles. A fishmouth incision is recommended, oriented so as to create radial and ulnar skin flaps.
Transection of the elbow flexor and extensor muscle groups should be performed approximately 3cm distal to the planned osteotomy level. Myodeses of the flexors and extensors should be performed to the humerus using unicortical suture anchors or bicortical transosseous sutures (ideally 2-0 or 3-0 Ethibond or Fiberwire), followed by myoplasty. A meticulous layered closure should then follow.

Postoperative Care

Dressing Care/Immobilization
Operative site dressing generally includes placement of Xerform or Vaseline gauze over the suture line, followed by sterile gauze and a low-tension kerlix wrap. When it is available, application of topical nitroglycerine ointment to the distal skin envelope and suture line is recommended to reduce the risk of soft tissue ischemia. In contrast, immediate application of a compression dressing or limb cast at the time of amputation is not recommended, as this may increase the risk of soft tissue ischemia in the event of significant postoperative residual limb edema. Operative dressings may typically remain in place for 3-4 days, after which point institution of daily dressing changes is recommended.
For lower extremity amputations, maintenance of bedrest is generally recommended for 48 hours postoperatively, after which point the patient may be cleared for mobilization to a chair with strict lower extremity elevation. Crutch training with physical therapy may begin on postoperative day 3-4. Bedrest precautions are generally not indicated for upper extremity amputees in the acute postoperative period.
In the setting of TTA, postoperative placement of a knee immobilizer is recommended for 4 weeks postoperatively in order to prevent the development of involuntary knee contracture. Analagous immobilization of TFA, TRA and THA patients is not indicated; however, prolonged utilization of slings in TFA patients should be avoided for similar reasons.
Residual limb suture removal is generally performed at four weeks postoperatively.
Antibiotic Prophylaxis
Broad spectrum oral antibiotics are generally recommended until operative site drain removal. The threshold for drain removal is typically less than 20cc of fluid per 24 hour period for three consecutive days. Most drains remain in place for 7-10 days postoperatively; of note, lower extremity drains typically demonstrate an uptick in output once patients begin to mobilize and should not be removed prematurely.
Anticoagulation
Both lower extremity and upper extremity amputation patients should be maintained on prophylactic doses of systemic anticoagulation until they are able to mobilize safely and independently (i.e., without nursing support).
Rehabilitation
Postoperative rehabilitation following amputation is critical to maximizing patients’ postoperative functional outcomes. In lower extremity amputees, physical therapy should be instituted on postoperative day 3-4, with a focus on core strengthening and contralateral lower limb optimization. TTA patient therapy should also focus on hip range of motion and strengthening on the side of amputation, but knee range of motion should be deferred until after removal of the knee immobilizer.
Isolated TTA patients typically do not require transfer to an inpatient acute care rehabilitation facility, but TFA patients generally will due to significant disturbances in their centers of gravity. In upper extremity amputees, occupational therapy should be instituted on postoperative day 3-4, with a focus on shoulder/elbow strengthening as appropriate and contralateral upper limb optimization.
Ideally, physical and occupational therapy should be continued throughout the acute postoperative recovery period and prosthesis fitting period (approximately 2-3 months total).
Prosthesis Fitting
Referral to a prosthetist is generally undertaken following residual limb suture removal at 4 weeks postoperatively. If the residual limb appearance is pristine at 2 weeks postop, consideration may be given to fitting the patient with a shrinker at that point; otherwise, shrinker therapy is initiated following suture removal.
Typically, fitting of the patient with a temporary check socket is undertaken by the prosthetist following 2-4 weeks of shrinker therapy. The duration of time required to ultimately transition to a definitive carbon fiber socket varies from individual to individual, but generally requires 4-8 weeks. TFA and THA patients often require more fine tuning for socket fitting than TTA and TRA patients, and should be counseled accordingly throughout their recovery period.

Special Considerations

Advanced Resurfacing Options
When feasible, every effort should be made to preserve large joint integrity in extremity amputations. For upper extremities, there is a substantial functional benefit of a TRA over a THA due to the incremental joint positioning options offered by preservation of the elbow joint. The same is true in TTAs versus TFAs due to preservation of the knee joint; in addition, studies have demonstrated significant alterations in metabolic energy expenditure the more proximal the level of lower extremity amputation due to alterations in gait kinematics.[5]
Such changes have been linked to increased rates of cardiopulmonary morbidity over time.
In the setting of extensive soft tissue compromise, preservation of large joint integrity may require employment of advanced soft tissue resurfacing strategies. In these circumstances, consideration should be given to the plastic surgery reconstructive ladder.
Assuming recruitment of local tissues is not an option, the least resource-intensive option for residual limb resurfacing will often be closure via split thickness skin grafting. Significant long-term disadvantages of grafting include susceptibility of the grafted skin to shear injury, lack of subcutaneous padding, contour irregularity and scar contracture; in austere environments, however, grafting may offer, at the very least, a short term closure solution. A more definitive solution to distal limb resurfacing may be consideration of free tissue transfer options including fasciocutaneous, musculocutaneous and muscle free flaps.
These solutions require more infrastructure and technical expertise than grafts due to their reliance on microsurgery and therefore may not be available in all settings. When feasible, however, free tissue transfer options offer the possibility of robust coverage with adequate padding, optimal contour and excellent fortitude.
Of note, when considering resurfacing possibilities, consideration should always be given to the possibility of utilizing portions of the amputated limb as substrate for reconstruction. This principle of considering the amputated limb to be a reservoir for spare parts is a cornerstone of reconstructive plastic surgery.
Neuropathic Pain Prevention
It is estimated that up to 85% of extremity amputees develop neuropathic pain following loss of their limbs. This pain may either be experienced as residual limb pain (i.e., pain at the amputation site itself), as phantom limb pain (i.e., pain in the lost limb), or a combination of the two.[6]
The source of neuropathic pain in the amputee population is believed to begin with the generation of symptomatic neuromas at the site of sensory or mixed nerve transection. A variety of techniques to prevent symptomatic neuroma development (e.g., traction neurectomy, phenol ablation, burying nerve endings in bone) have been espoused over the course of the past several decades, but have not proven to be reliably efficacious.
More recently, however, two techniques to prevent symptomatic neuroma development have shown promise: targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) construction.[7],[8] In the former, a transected nerve ending is coapted to one of the motor nerve inputs to a nearby neurotized, vascularized muscle; in the latter, a transected nerve ending is wrapped with a small free muscle graft. Both techniques rely on the idea of promoting directed reinnervation of tissues, rather than permitting the proliferation of disorganized axonal regrowth; stated plainly, they provide a severed nerve ending with “somewhere to go and something to do.”
At this point, sufficient evidence exists to support the employment of TMR and/or RPNI construction techniques at the time of amputation as an approach to prevent the development of downstream neuropathic pain. Of note, TMR and RPNI construction may be mixed and matched within the same residual limb, depending on the availability of innervated and non-innervated muscle. Specific consideration to addressing the following distal nerves should be undertaken via these techniques, by amputation level:
  • TTA: Tibial, superficial peroneal, deep peroneal, saphenous, medial sural, lateral sural
  • TFA: Common peroneal, tibial (via sciatic nerve fascicular split), posterior femoral cutaneous, lateral femoral cutaneous, anterior femoral cutaneous
  • TRA: Median, ulnar, radial, lateral antebrachial cutaneous, medial antebrachial cutaneous
  • THA: Median, ulnar, radial, musculocutaneous, medial brachial cutaneous, lateral brachial cutaneous
Osteoplastic Techniques
A variety of advanced skeletal modifications specific to amputation scenarios have been proposed over the past several decades to optimize residual limb load bearing and/or facilitate prostheses socket fitting. Definitive data regarding the efficacy of such techniques remains elusive – however, consideration of such techniques may be warranted when permitted by a given patient’s anatomy and a given surgeon’s resources.
All such techniques include the additional risk of malunion or nonunion due to the additional requirement for appropriate bone healing; furthermore, they all require more prolonged periods of non-weightbearing in the acute postoperative period. These techniques include, but are not limited to, the following:
  • The Ertl Procedure: Typically reserved for the TTA scenario, the Ertl Procedure involves creation of a tibiofibular bone bridge at the distal osteotomy site of both bones. The intent of the Ertl is to create a stable tibiofibular articulation to enhance direct loading tolerance of the distal residual limb[9]; whether or not this results in a significant gain of function for a TTA patient remains controversial. The Ertl has furthermore been proposed in the setting of TRA; however, establishment of a distal radioulnar union results in limitation or prevention of forearm supination/pronation and is therefore not advised.
  • Shortening Osteotomy: In the setting of TFA or THA, resection of a diaphyseal segment of the femur or humerus followed by subsequent internal fixation may be undertaken in lieu of a standard distal osteotomy. The potential value of this technique is preservation of the distal condyles of the extremity long bones, which provides a distal bony flare that may augment purchase and stabilization of a limb socket.
  • Gritti-Stokes Patelloplasty: Also reserved for the TFA scenario, this technique involves resection of the distal femur at the supracondylar level and subsequent fixation of the patella to the distal femoral osteotomy site as an end-cap.[10] The intent of the Gritti-Stokes technique is to increase weightbearing tolerance at the distal end of the femur and potentially limit TFA site osteomyelitis by eliminating the distal medullary canal exposure typical of a standard TFA.
  • Angulation Osteotomy: Generally described for the THA scenario, this technique involves creation of an angulated bone segment at the distal end of the humeral osteotomy.[11] The intent of this technique is to limit unwanted rotation of a humeral socket via creation of a hook in the distal residual limb without limiting shoulder range of motion.
Proprioception Preservation
The recently described agonist-antagonist myoneural interface (AMI) is a surgical construct designed to preserve or restore proprioception in an amputated limb.[12] Creation of an AMI involves coaptation of two innervated, vascularized muscles that have a natural agonist-antagonist relationship in an intact limb. AMIs may be constructed utilizing native tissues, or via regenerative techniques such as TMR or RPNI construction.[13],[14]
A single AMI is constructed as an emulator for each joint for which restoration of proprioception is desired. To date, AMI construction has been described in the setting of acute TTA, TFA, TRA and THA. Early results from patients who have undergone these procedures have evidenced an unprecedented degree of phantom limb sensation that appears to augment residual limb function, diminish neuropathic pain and prevent downstream limb atrophy.[15],[16]
Vascularized Composite Allotransplantation
The first transplantation of a hand was performed in 1964, harkening the development of the field of vascularized composite allotransplantation (VCA).[17] Since that time, over 100 upper extremity and at least 4 lower extremity transplantation procedures have been performed worldwide.[18]
These procedures require obligatory lifelong immunosuppression and are characterized by extended reinnervation recovery periods. Furthermore, functional outcomes from such procedures have been highly variable and chronic rejection has emerged as a cause for eventual graft failure in a subset of transplanted patients.[19]
At present, no formal recommendations regarding acute management of extremity amputation sites to optimize patients for downstream VCA candidacy have been developed other than to encourage preservation of optimal residual limb length. Whether VCA emerges as a more widespread option for extremity amputees over time will likely depend on our ability to induce immunologic tolerance and augment nerve regrowth.
Osseointegration
Standard socket interfaces for extremity prostheses carry with them a host of drawbacks including skin irritation due to friction and sweat, frequent refitting requirements due to progressive limb atrophy and difficulty achieving stability in the short residual limbs. An alternative to the standard socket interface is the placement of an implantable device in the medullary canal of the residual limb bony infrastructure that includes a distal abutment that penetrates the distal limb skin and serves as a direct prosthetic attachment point. This device – known as an osseointegrated implant – completely obviates the need for a socket.[20]
Osseointegrated implants have been employed with increasing regularity in TFA and THA scenarios, and have more recently been applied to TTA and TRA scenarios, as well.[21] Placement of such implants is not generally undertaken at the time of acute amputation, but may be considered once a patient has demonstrated an inability to successfully utilize a standard socket. Osseointegrated implants require patients to observe a heightened degree of hygiene in their residual limbs and carry with them the lifelong risk of implant infection and/or failure.

Conclusions

Severe extremity injuries requiring amputation are being witnessed with increasing frequency in the setting of war-related activities. The goals of limb amputation have expanded since the development of basic limb sacrifice techniques; modern notions of limb amputation are increasingly framing it as a reconstructive procedure rather than a surgical failure.
While there are general overarching principles that hold true for limb amputations at all levels, there are specific concerns that must be considered for TTA, TFA, TRA and THA scenarios, respectively. In addition, there are a number of advanced reconstructive techniques that are available to augment extremity amputation outcomes that may be considered if time, resources and surgeon skill allow.

References

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