Approximately 60% of individuals with an amputation have post-amputation pain in the residual limb, which can severely limit function, impair quality of life, and significantly impede rehabilitation (1). Residual limb pain should be evaluated and treated aggressively because some causes can be dangerous.
Phantom limb sensation is a desirable, nonpainful sensory abnormality that can improve proprioception and is distinct from phantom limb pain.
Persistent residual limb pain is a chronic condition that differs from phantom limb pain and phantom limb sensation.
General reference
1. List EB, Krijgh DD, Martin E, Coert JH: Prevalence of residual limb pain and symptomatic neuromas after lower extremity amputation: a systematic review and meta-analysis. Pain 162(7):1906-1913, 2021. doi:10.1097/j.pain.0000000000002202
Causes of Pain in the Residual Limb
Causes of residual limb pain include
Postoperative surgical pain
Deep tissue infection (eg, osteomyelitis, vascular graft infection)
Pressure points with or without skin breakdown
Neuroma
Neuropathy
Bone spurs
Limb ischemia
Postoperative surgical wound pain typically resolves as tissues heal, usually over 3 to 6 months. Pain continuing beyond that time has numerous causes, including infection, wound dehiscence, arterial insufficiency, hematoma, insufficient muscle padding over cut ends of bone, and a poorly fitting preparatory prosthesis.
Neuropathic pain is common in patients and is usually described as a shooting or burning pain and typically develops within 7 days of amputation. It can go away on its own but is often chronic. It can be unrelenting and severe, or intermittent. It often is the result of nerve damage from an injury or the severing of nerves during the amputation.
Painful neuroma can occur in any severed nerve (from surgery or trauma) and may cause a focal or enlarged area of pain that can be temporarily blocked (as a diagnostic maneuver) by local anesthetic injection.
Patients also can experience pain in other limbs, joints, back, and neck due to the compensatory body movements done to make up for the lost function of the amputated part.
Phantom limb pain
Most patients experience phantom limb pain at some time. The phantom aspect is not the pain, which is real, but the location of the pain—in a limb that has been amputated. The mechanism is believed to involve peripheral and central factors. Onset and duration typically is within days following amputation but could be delayed months to years. Terms used to describe phantom limb pain include tingling, shooting, stabbing, throbbing, burning, aching, pinching, clamping, and vise-like squeezing.
Phantom limb pain is often more severe soon after the amputation, then decreases over time. Postsurgical desensitizing therapies are available and recommended to reduce pain during initial weight-bearing in the prosthesis. For many patients, phantom limb pain is more common when the prosthesis is not being worn, for example, at night. The risk of having this pain is reduced if both a spinal anesthetic and a general anesthetic are used during surgery.
Other nonpharmacologic therapies may be tried to relieve the pain, including transcutaneous electrical nerve stimulation (TENS), acupuncture, and spinal cord stimulation.
Phantom limb sensation
Most patients experience phantom limb sensation, which is the feeling that the amputated part is still present. Phantom limb sensation must not be misinterpreted as phantom limb pain. Phantom limb sensation can be a particular problem in patients with lower limb amputations during nighttime trips to the bathroom. They believe their limb is still there and take a step and fall or injure their residual limb.
Persistent residual limb pain
Some patients with a socket-secured prosthesis (SSP) experience chronic, recurring residual limb pain caused by chronic skin irritation from sweating and pressure/friction ulcers. This results in reduced prosthesis control, loss of function, reduced independence, and decrease in quality of life. Persistent pain can affect sleep, increase stress levels, and increase mental health problems (eg. anxiety, depression, substance use disorders). Persistent pain is more common in patients with short remaining skeletal structures and/or soft-tissue deformities of the residual limb.
Evaluation of Pain in the Residual Limb
History and physical examination are often adequate to evaluate residual limb pain, but sometimes testing is needed.
Pain accompanied by skin changes (eg, erythema, ulceration) suggests skin irritation or infection. Skin infection and breakdown have clear, visible manifestations and should be dealt with. Expanding painful and tender erythema suggests cellulitis. In patients with known vascular disease, ulceration may also be due to recurrent ischemia.
Constant pain without skin changes suggests neuropathy, complex regional pain syndrome, deep tissue infection, and in patients with known vascular disease, recurrent ischemia. If the pain increases with compression and/or there are systemic manifestations (eg, malaise, fever, tachycardia), there may be deep infection.
Deep tissue infection may be more difficult to diagnose because focal swelling and erythema may not become apparent until pain has been present for some time; systemic manifestations such as fever or tachycardia may appear first and should not be ignored.
Intermittent pain without skin changes that occurs with use of the prosthesis and resolves with removal suggests fit problems, neuroma, or bone spurs. Dysesthesia and/or a neuropathic quality to the pain suggests neuroma. Intermittent pain unrelated to use of the prosthesis and with no skin changes suggests various underlying possibilities including neuroma, disuse atrophy of muscles with trophic changes in vessels, reduced blood supply, and deep bone ache due to open bone marrow.
The diagnosis of a neuroma is suggested by history and physical examination. Pain from a neuroma may have neurogenic characteristics such as feeling electrical, shooting, tingling, sharp and stabbing, or prickly sensations. The pain is typically localized to the residual limb. Other symptoms that suggest neuroma include dysesthesia (unusual and unpleasant sensations) that occurs without stimulation, upon contraction of residual-limb muscles, or with light palpation of skin. Neurogenic pains that occur while using the prosthesis and disappear quickly or slowly upon removal of the prosthesis also suggest a neuroma. The longer the neuroma is irritated, either mechanically by the prosthesis or from muscle contraction, the longer the dysesthesia takes to dissipate. Magnetic resonance imaging and/or ultrasound can be used to confirm the diagnosis of neuroma.
Patients whose amputation was necessitated because of ischemic peripheral arterial disease are at risk for further ischemia, which can be difficult to diagnose but may be suggested by a very low transcutaneous oxygen tension (< 20 mm Hg) on the skin of the distal limb.
Treatment of Pain in the Residual Limb
Prosthesis modification and/or discontinuance of prosthesis use until healing
Pharmacologic therapy
Surgical neurectomy
Stretching and strengthening exercises
Transcutaneous osseointegration
Treatments of postoperative surgical wound pain are directed at the cause and may also include prosthesis modification, discontinuance of prosthesis use until healing, and analgesics.
Treatment of neuropathic pain is multimodal (eg, psychologic treatments, physical methods, antidepressants, or antiseizure medications).
In patients with a neuroma causing severe pain, surgical neurectomy may be advised.
For pain in other limbs, joints, back, and neck due to compensatory body movements, the prosthetist should regularly evaluate static and kinematic efficiency of the prosthesis and make adjustments as necessary. In addition, regular stretching and strengthening exercises help balance the body and relieve pain. A physical therapist can help design an appropriate exercise program.
Transcutaneous osseointegration
Transcutaneous osseointegration is an alternative for patients who have experienced problems from a socket-secured prosthesis, including residual limb pain (1). This surgical reconstructive procedure involves inserting a biocompatible implant directly into the residual bone, which modifies the interface between the residual limb and traditional socket. Various prosthetic appendages can be attached directly to the implant, eliminating the problem of pressure on tissues not morphologically designed for weight bearing. Benefits include improved proprioception, balance, and mobility; elimination of skin problems from friction and pressure between the residual limb and a socket; and reduced nerve pain. An opening in the skin at the end of the residual limb (stoma) allows the implant to extend out of the limb and attach to component elements (eg, joints, appendages, shock and shear attenuation device, and alignable endoskeletal system).
The most common locations of amputation most suitable for osseointegration include
Transfemoral
Transtibial
Transhumoral
Transradial
Transphalangeal
Osseointegration should be considered in patients with
Complications from socket-secured prosthesis (eg, persistent residual limb pain, recurrent skin infections, ulcerations)
A short residual limb that prevents adequate securing of socket
Residual limb soft tissue volume fluctuation preventing adequate securing of socket
Socket slipping due to excessive perspiration
The residual limb must also have adequate bone length and volume and skeletal maturity.
Contraindications to osseointegration include
Abnormal residual limb skeletal anatomy that prevents implant integration
Bone disease that compromises the skeletal integrity of the residual limb (eg, osteoporosis, osteomyelitis)
Adequate socket-secured prosthesis (eg, functional for required activities and no chronic residual pain issues)
Active medical issues that would contribute to poor healing (eg, severe peripheral arterial disease, uncontrolled diabetes)
Smoking and an inability to stop smoking during prescribed timeframe (resulting in poor bone healing)
Likelihood of noncompliance with treatment and follow-up requirements
Successful osseointegration requires a multidisciplinary team including the surgeon, prosthetist, and physical therapist. Candidates follow a comprehensive screening procedure. The prosthetist evaluates the patient’s physical and functional capabilities and daily activities that will determine specific prosthetic component elements. After the procedure, rehabilitation protocols and care guidelines must be followed to ensure that patients continue to receive the required clinical support and long-term follow-up care required for a successful outcome.
The risk of complications from transcutaneous osseointegration is low but includes infection and fracture of the bone in the residual limb, as well as loosening of the implant after integration. To minimize potential harm, a mechanism is inserted between the implant and the prosthesis that automatically releases during a severe fall. This protects the implant and reduces the possibility of bone fracture.
Treatment reference
1. Hebert JS, Rehani M, Stiegelmar R: Osseointegration for Lower-Limb Amputation: A Systematic Review of Clinical Outcomes. JBJS Rev 5(10):e10, 2017. doi:10.2106/JBJS.RVW.17.00037
