Musculoskeletal Injuries

Injury patterns among amputees are similar to those for athletes without disabilities; however, the severity and location of the amputation dictates the frequency and type of injury. Lower extremity amputees are at risk for injuries in both intact and residual limbs. The distal residual limb is often the site of skin trauma due to the prosthesis. Altered biomechanics because of the asymmetric need for power and propulsion may predispose athletes to hip, sacroiliac, and lumbar spine pain. Alternatively, an amputee may rely too heavily on the intact limb, which can increase the risk for overuse injuries and osteoarthritis.

Similarly, in upper extremity amputees, altered use and load patterns of the intact limb can result in pain and injury to either limb or axial structures. Overuse injuries such as shoulder impingement, rotator cuff tears, epicondylitis, and peripheral nerve entrapments are common in the intact limb of upper extremity amputees. Differences in weight and swing excursion between the upper extremities, as well as the need to compensate at the shoulder for loss of distal joint function, may cause significant asymmetry in the demands of the thoracic and cervical spines and paraspinal and parascapular musculature, resulting in pain and dysfunction. Treatment for many of these conditions is identical to that for nonamputees. Additionally, however, precise fitting of prostheses in this population is a critical aspect of beneficial treatment.

Dermatologic Conditions

After amputation of the limb and subsequent fitting of a prosthesis, the skin of the distal portion of the residual limb becomes a weight-bearing surface and as a result is at increased risk for skin disorders. Rashes are frequently observed in persons who use prostheses. A noninfectious allergic rash should spur examination of the type of liner used, with the goal of incorporating material that is less irritating and that promotes greater perfusion of sweat away from the skin. Rashes can be prevented by cleaning the residual limb and prosthesis regularly.

Prevention of infections is a key priority and often a source of concern. Verrucous hyperplasia is a wartlike lesion that may develop at the distal end of the residual limb. It may occur as a result of proximal residual limb constriction from a socket or wrap that has caused decreased pressure in the distal residual limb. The prevention and treatment of verrucous hyperplasia consists of equal distribution of pressure through the residual limb, akin to a total contact socket.

Blisters and sores are very common and can occur as a result of friction between skin of the residual limb and the prosthesis. Skin breakdown may also occur when pressure is applied disproportionately to a pressure-sensitive area of skin on the residual limb, such as the tibial tubercle in a transtibial amputee. The risk may be compounded by impaired sensation in the residual limb, and sweating with athletic activity can increase moisture at the skin-socket interface and heighten the risk for skin breakdown. Environmental conditions may also play a role, especially in marine sports (e.g., swimming, kayaking, and rowing) and during participation in hot weather. Other risk factors include the increased frequency and intensity of weight bearing associated with athletic training and competition. A properly fitting socket will normally prevent blisters and sores, and it is important to maintain a good socket fit by adding and removing socks throughout the day to adjust for volume reduction and to periodically assess and adjust the fit to counter weight loss over a prolonged period. Other preventive measures include silicone liners, padded sleeves, socks, and additional padding.

Heterotopic Ossification

The formation of bone in tissues that are not normally ossified, heterotopic ossification (HO), usually evolves after traumatic brain injury, spinal cord injury, burns, and total arthroplasty. Recently, HO has been reported to develop frequently in injured tissue of residual limbs in traumatic amputees, which may increase risk of skin breakdown or stimulate pain with weight bearing. HO is also more likely to develop around joints and muscle adjacent to trauma and typically develops within the first 6 months to a year after amputation. The development of HO typically occurs during the time an amputee is beginning prosthetic training. Thus the majority of persons with HO are diagnosed prior to engaging in athletic competition, which facilitates modifications in design of the socket and vigilance for signs of skin breakdown.

Numerous treatments for HO have been studied in nonamputee populations, but to date, an effective protocol for the prevention of HO after amputation is lacking. However, a beneficial effect of nonsteroidal antiinflammatory drugs in the prevention of HO after total hip arthroplasty is well documented. Bisphosphonates are widely used in the spinal cord injury population for osteoporosis and the prevention and treatment of HO. Unfortunately, significant gastrointestinal and renal adverse effects of these medications and of bisphosphonates in particular mandate extreme caution prior to their use in a competitive athlete. Eventually, surgical excision of HO may be essential if conservative measures fail to restore adequate levels of function.

Neuroma

Neuromas form at the distal end of transected nerves in the residual limbs of amputees. The development of a neuroma in a weight-bearing structure or in its vicinity can cause severe pain with ambulation and weight bearing and limit an athlete’s ability to train and compete. Treatments include prosthetic modification to relieve pressure, oral medications, including antiepileptic agents and tricyclic antidepressant drugs, injections of corticosteroids and local anesthetics into the neuroma, and radiofrequency ablation of neuromas. Many common medications that are used may be restricted in competition by the World Anti-Doping Agency (WADA), and clear knowledge regarding these limitations is vital for medical practitioners. We encourage medical practitioners who are caring for athletes with disabilities to visit WADA’s Web site at www.wada-ama.org to review approved and restricted medications “in and out of competition.” Surgical excision may ultimately be necessary if conservative treatments fail.

Musculoskeletal Injuries

Wheelchair athletes are at risk for routine musculoskeletal injuries, such as muscle strains, at rates comparable with those of able-bodied athletes; however, the distribution of these injuries is obviously quite different because of upper extremity use for wheelchair propulsion. Injuries in this population may affect participation and performance to a disproportionately high degree compared with able-bodied athletes. One study noted that 32% of all injuries resulted in “time loss” of more than 3 weeks.

Shoulder and wrist injuries are common. The injuries maybe unilateral or bilateral, are equally frequent in location, and are often induced by overuse. However, sports such as alpine skiing that rely on outriggers or sports featuring contact such as wheelchair rugby may have a higher ratio of traumatic injuries relative to other events. A history of shoulder pain is reported in more than 90% of selected wheelchair athlete populations, with an increasing prevalence in proportion to the amount of trunk and upper extremity disability. Shoulder impingement syndrome is the most common injury; bicipital and rotator cuff tendinopathy and tears are also common. Wheelchair athletes often have a protracted scapular position with dynamic scapular dyskinesis, resulting in loss of subacromial space. Additionally, the humeral head is often elevated as a result of relative muscle strength imbalance, favoring shoulder abduction strength over adduction and rotational strength. This risk can potentially be modifiable by alterations in trunk inclination, backrest height, and the position of the wheelchair axle relative to the shoulder. Physical therapy should improve shoulder flexibility, correct scapular kinematics, and address shoulder muscle imbalances.

Lower extremity injuries are also common in this population, although they are less frequent than in ambulatory athletes. Compared with upper extremity injuries caused by overuse, these injuries are usually acute and posttraumatic. Direct contact with another wheelchair or an object during team sports and falls are common and increase the risk for trauma of the head and neck, which may be compounded by the high rates of osteoporosis observed in lower extremities in this population. Thus clinicians should be vigilant because even minor trauma may result in fractures, and any resulting deformity or angulation after healing may adversely affect available seating positions, increase the risk for pressure sores, and alter functional status.

Peripheral Nerve Entrapment

Peripheral nerve entrapments are commonly encountered in wheelchair athletes. The prevalence of carpel tunnel syndrome is approximately 50%. Other significant entrapment neuropathies include ulnar neuropathy at the wrist, ulnar neuropathy at the elbow, and radial neuropathy. Shoulder muscle imbalance and scapular dyskinesis may also result in suprascapular neuropathy at either the suprascapular or spinoglenoid notches. In addition to standard therapies, protection of the wrist and elbow with padded gloves and sleeves, use of a wheelchair that has been properly fit to the athlete, and use of an adequate range of motion and proper techniques during propulsion to decrease push rates and forces may help with prevention and treatment.

Thermoregulation

Altered sympathetic, vasomotor, and sudomotor responses and diminished rates of venous return from the loss of muscle-pumping action results in a diminished ability to sense and respond to thermal imbalance. The loss of skeletal muscle and function also impairs the response to negative thermal imbalances because of a reduced capacity for shivering. These factors increase the risk for hypothermia and exertional heat illness, especially in persons with spinal cord lesions above the T6 level.

Pressure Sores

Pressure sores are common among wheelchair athletes, particularly those with a spinal cord injury. Prolonged pressure, typically over bony prominences such as the sacrum and ischial tuberosities, combined with insensate skin that is moist from activity, increase compressive and shears forces, resulting in local tissue ischemia and injury. Wheelchair athletes with altered trunk stability often maintain a flexed lower extremity posture at the hips and knees that further distributes the athlete’s weight to “at-risk sites.” Vigilance is mandatory for pressure sore prevention, including skin checks, shifting of weight every 15 to 20 minutes to relieve pressure, the use of appropriately fit seat cushions, and maintenance of a dry environment.

Spasticity

Spasticity is common in wheelchair athletes who have spinal cord injuries and is manifested by involuntary muscle contraction, hyperreflexia, and velocity-dependent increases in tone. Synergistic muscle activation patterning may inhibit performance by altering positioning within the wheelchair, item control/accuracy, and propulsion. However, it is important to note that in some cases, spasticity may be beneficial for these functions when other voluntary muscle action is insufficient. It is important for the sports physician to remember that spasticity is primarily a velocity-dependent increase in tone, and thus a routine bedside examination may not be conducive to a thorough appreciation of the detrimental effects of spasticity unless sports activities are entirely replicated.

Spasticity is usually treated with oral medications, physical therapy that emphasizes range of motion, and tone-reducing orthoses. In more advanced cases or in cases in which the athlete cannot tolerate the sedative effects of antispasticity medications, Botox injections can focally reduce high levels of spasticity in a dose-dependent fashion. Surgical approaches such as muscle/tendon lengthening, tendon transfers, and selective dorsal rhizotomy may be considered in refractory cases.

Neurogenic Bladder and Bowel

Bladder dysfunction is common in wheelchair athletes who have spinal cord injuries and spina bifida. This dysfunction can result in urinary retention, often necessitating indwelling, suprapubic, or intermittent catheterization and resulting in increased rates of urinary tract infections and stone formation. Clinical presentation may include fever, fatigue, a general sense of unease, discomfort in the area of the bladder and kidneys, autonomic dysreflexia, incontinence, and an increased level of muscle spasticity.

Bowel dysfunction is also common in persons with spinal cord injuries and spina bifida. Injuries above the S2-S4 spinal cord segments results in a reflexic neurogenic bowel, whereas injuries distal to these segments or involving the destruction of anterior horn cells (at these levels) result in an areflexic bowel. In addition to utilizing other methods of facilitation, these persons are counseled to initiate regular bowel programs at the same time of day to condition the bowel to achieve effective defecation and avoid incontinence.

In the sports setting, the athlete may not adhere to appropriate frequency or technique of clean intermittent catheterization or appropriate timing of their bowel program because of an overfocus on training, which may propagate infection, reduce vigilance of hydration status, and increase the risk of incontinence. Clinicians should counsel athletes on the importance of bowel and bladder management, which has significant performance and practical implications. Athletes should also be counseled to undergo slow alterations in bowel management to best accommodate their expected competition schedule at upcoming events and to always be cognizant regarding the available facilities for bowel and bladder management at each venue.

Heterotopic Ossification

HO may occur in up to 36% of patients with spinal cord injuries, and amputee athletes competing in the wheelchair class may also be at risk. The period of highest risk for development of HO is approximately 4 months after spinal cord injury. HO most commonly affects the hips but may also affect the knees, shoulders, and elbows. HO may limit function and performance by restricting range of motion for different seating positions, propulsion, and other tasks; it also may increase the risk for pressure sores and nerve entrapments.

Autonomic Dysreflexia

Autonomic dysreflexia (AD) is a medical emergency usually seen in persons with complete spinal cord injuries involving or above the T6 segment. Noxious stimuli below the level of injury can cause reflexive sympathetic activity that cannot be modulated by supraspinal centers of control, resulting in high levels of sympathetic activity below the level of injury and incomplete parasympathetic compensation above the level of injury. During an episode of AD, persons typically experience hypertension and headache due to vasoconstriction below the level of injury, along with skin flushing, piloerection, diaphoresis, and bradycardia above the level of injury. Although mortality is rare, significant morbidity may result, including cerebral hemorrhage, seizures, and myocardial infarction. Treatment should include sitting the person upright, removing restrictive clothing, and searching for the source of the noxious stimulus, which is commonly a distended bladder or impacted colon, pressure sores, or another injury. Systolic pressures of 150 mm Hg should be treated with short-onset and half-life antihypertensive medications. Transdermal nitro paste is highly effective and can be removed easily after resolution of the episode of AD to avoid subsequent hypotension.

An unsettling trend among wheelchair athletes is the intentional use of AD to improve performance during competition, a phenomenon known as “boosting.” Athletes will create a self-induced noxious stimulus via methods such as kinking a bladder catheter, sitting on ball-bearings, fracturing a toe, or excessively tightening legs straps in order to induce AD. This strategy may lead to improvements in peak heart rate, peak oxygen consumption, and blood pressure and has been shown to enhance “racing time” by approximately 10%. For obvious health and safety reasons and to promote fairness during competition, the International Paralympic Committee has banned the use of induced AD from competition.