Knee-ankle-foot orthoses (KAFOs) and trunk-hip-knee-ankle-foot orthoses (THKAFOs) can enable some patients with certain diseases, injuries, or congenital anomalies to achieve functional ambulation. Orthotic care is ideally provided by a clinic team consisting of a physician, orthotist, and physical therapist. Concerns shared by the physical therapist revolve around:
- Evaluating the patient to determine whether the individual is a candidate for an orthosis
- Identifying which orthotic functions would be most beneficial
- Inspecting the fit of the orthosis
- Training the patient in ambulatory functions
- Instructing the patient in care of the skin and orthosis
EVALUATING THE PATIENT
Key aspects of evaluation include:
Musculoskeletal examination, particularly documenting active and passive range of motion of all joints of both lower limbs, conducting a manual muscle test, and assessing the patient’s ability to accomplish activities of daily living, especially walking
Neuromuscular examination, specifically detailing the extent of any spasticity or other manifestation of neuropathy, and testing sensory acuity
Integumentary examination, namely inspecting the skin to detect any decubitus ulcers, scars, grafts, and any other abnormalities that might affect orthotic use
Cardiopulmonary examination, to predict whether the patient is likely to have the physiological capacity for ambulation
Psychosocial assessment focusing on the patient’s cognitive status, motivation to engage in physical rehabilitation, vocational and avocational ambulatory requirements, and home conditions such as stairs, carpets, and threshold barriers.
The evaluation enables the therapist to formulate rational long-term and short-term goals. An important aim of the thorough assessment is to predict, on a joint-by-joint basis, whether an orthosis should resist or assist motion or transfer force from one portion of the limb to another. These insights, discussed with all members of the clinic team, should result in prescription of the most suitable orthosis for the patient.
Once the orthosis is delivered to the patient, the physical therapist should check each component of the device to confirm that it fits and functions properly. The patient must not be expected to wear an uncomfortable orthosis. Well-contoured bands, cuffs, and brims minimize pressure by maximizing the area covered by the orthosis. Contact between the orthosis and the body should be snug but not constricting. A tight band will compress superficial blood vessels, causing pain and potential tissue breakdown. Equally important, the contact should not be too loose, as this will likely result in friction as the patient moves and may also irritate the skin. For example, a KAFO that has a loose thigh band will abrade the skin as the wearer passes through the stance phase of gait. The knee lock or other components must operate smoothly and reliably for the patient to obtain optimum function while wearing the orthosis.
Training the patient often begins before provision of the orthosis. Ambulating with lower-limb orthoses usually depends on substantial trunk and upper–limb motor power and coordination. Aerobic conditioning is central to pre-orthotic and orthotic gait training. The therapist also teaches the patient how to avoid formation of hip, knee, and ankle contractures by appropriate positioning during the times when the person is not exercising. Ambulation with orthoses requires that the patient learn how to don and doff the devices, rise from the wheelchair or other seat, and return to sitting safely.
Many people who wear KAFOs use crutches or other assistive devices when walking. The therapist is responsible for selecting the most suitable design, adjusting them to fit the patient, and training the individual to integrate the assistive devices in whatever gait patterns might be employed. Reciprocal gait patterns, namely the two-, three-, and four-point gaits, involve independent movement of each hip. These patterns are likely to suit patients with lower motor neuron disorders, such as poliomyelitis. The three-point pattern is reserved for those who must limit weight-bearing through one lower limb. Some orthoses, such as the reciprocating gait orthosis, permit the patient to advance the right lower limb while the left limb remains extended. The sequence for taking a left step requires 1) shift weight to the right lower limb, 2) tuck the upper trunk backward, 3) push forcefully on the crutches or other ambulatory aid, and 4) kick the left leg forward. The patient repeats the sequence with the right lower limb. Simultaneous gaits, including the drag-to, swing-to, and swing-through patterns, depend on forceful propulsion provided by the shoulder girdle and upper limbs. These patterns compensate for inability to control the hips separately, whether because of pathology or orthotic restriction.
Care of the skin is imperative if the patient is to continue orthotic use safely. Either the patient must learn to inspect all portions of his body in contact with the orthosis or some member of the household must perform this essential task. Orthotic fit needs to be adjusted wherever any incipient sites of irritation appear; otherwise, development of decubitus ulceration will preclude orthotic wear and may have profoundly negative effects on the patient’s health. The wearer must also know how to take care of the orthosis, keeping it clean, maintaining shoes in good repair, and returning to the orthotist whenever the device malfunctions.
DIFFICULTIES AND OPPOSITION
Even with a well-designed training program as outlined above, many patients are reluctant to wear KAFO and higher lower-limb orthoses. Others may consent to wear orthoses initially but abandon them even though the devices provide needed stability and may facilitate ambulation. Reasons for not using carefully prescribed orthoses that fit and function well reflect physiological, psychosocial, and practical deficiencies inherent in KAFOs and higher orthoses.
Physiologic problems associated with orthotic wear are the awkward, slow ambulation accomplished with substantial energy expenditure. The deficiency is especially apparent compared with wheelchair mobility, which is faster and requires much less effort. Some people with lower motor neuron or musculoskeletal disorders who are fitted with a unilateral KAFO can walk nearly as well without the orthosis. The patient who has uncontrolled edema or who gains weight risks skin injury if the orthosis is permitted to exert undue pressure on the body. The individual with sensory loss may not be aware that the orthosis no longer fits unless skin inspection is performed vigilantly.
Psychosocial issues confound orthotic acceptance. Even though most lower-limb orthoses are worn under clothing, it is virtually impossible to disguise the extra bulk that an orthosis adds to bodily contours. The orthosis may be particularly noticeable when the wearer sits. Hinges are apt to alter the silhouette at the knee, preventing trousers from draping naturally. Orthoses often present an auditory distraction, especially when the knee lock engages, although some patients state they like to hear when the lock is in place. Asymmetrical foot falls are another distraction for the person who wears a unilateral KAFO. The patient may perceive the device as visible evidence of abnormality. Despite vastly increased public acceptance of people with disabilities, the bitter reality remains that for some individuals, disability still represents stigma. The orthosis is tangible evidence of bodily insufficiency. For some persons, particularly those with late-onset poliomyelitis syndrome, professional recommendation that the patient would now benefit from returning to orthotic wear may be demoralizing. The new prescription may be interpreted as signaling defeat after decades of managing without orthoses. The memory of the heavy, cumbersome, leather-steel orthoses commonly used in the mid-twentieth century may be so distasteful that the patient is unaware of modern designs and materials or doubts that streamlined orthoses are sufficiently stable.
A positive psychosocial change that may discourage orthotic wear is the greater public acceptance of wheeled mobility. Thanks to the Americans with Disabilities Act, places of public accommodation must be accessible to people who use wheelchairs. The legal requirement for ramps, wider doorways, larger restrooms, and other architectural features has done much to change public attitudes toward disability. Celebrities and other individuals appear in public moving about in wheelchairs without much notice. Wheelchair sports have glamorized use of the equipment, and redesign of wheelchairs and other modes of mobility offer candidates a much wider array of options. Although wheelchairs are bulkier and heavier than orthoses, patients who prefer to present themselves seated are willing to find ways to maneuver in confined environments.
Finally, practical difficulties can dissuade the patient from wearing KAFOs and more extensive orthoses. The THKAFO is especially difficult to don, as well as being heavy and cumbersome. Consequently, it is seldom worn after the client is discharged from the rehabilitation program. Donning is a major determinant of orthotic usage. Regardless of the appliance, the patient must be able to don it accurately, independently, and rapidly. Even though a family member may promise with utmost sincerity to assist the patient with an orthosis, the overwhelming reality is that other household concerns take precedence over coping with the orthosis. KAFOs and higher orthoses abrade the interior of trouser legs to the extent that eventually the fabric weakens enough to develop holes. Some patients anticipate this problem and reinforce the inside of pants legs before damage occurs.
All orthoses add weight to the body. The weight of extensive orthoses is especially burdensome when the wearer walks, climbs stairs, and lifts the appliance in preparation for donning. Another inherent problem with orthoses is that, regardless of design, they cover part of the body. Skin under the orthosis cannot dissipate heat or perspiration readily, even though patients are advised to wear fabric under the orthosis. Although long uprights provide maximum leverage through which the orthosis applies force longitudinally, an overly long leg or thigh upright can impinge on the groin or fibular head, causing intolerable discomfort. Although use of leather is declining, those orthoses with leather cuffs or upholstering are difficult to clean. A practical concern is particularly pertinent in the case of incontinent patients. Velcro® straps collect lint, which interferes with their ability to fasten properly; they also catch other fabric, compounding the dressing problem. Proper selection of materials and designs should enable provision of an orthosis sufficiently durable to meet the stresses imposed by each patient. Nevertheless, screws and rivets occasionally dislodge. Other sources of orthotic failure are patients who exert undue force on the orthosis because of obesity, extreme torsional movements, or falls. The resulting need to disturb family or vocational routines to take the time to visit the orthotist may convince the patient to avoid future problems by abandoning the orthosis.
A final practical concern is the expense of orthoses. Although a major part of the cost is usually reimbursed by public or private insurance, paying the balance may be daunting for some patients. A few people do not have insurance or personal resources to pay for orthoses. Several factors can offset the cost of orthoses. When orthoses facilitate rehabilitation, the length of in-patient hospital stay can be reduced; this results in considerable savings. In those instances when patients can resume functional ambulation while wearing orthoses, their cost is vastly compensated by lesser or no reliance on family or paid assistants. Ambulation may enable the individual to enter or reenter the work force with consequent payment of taxes, which usually far exceeds the cost of the orthoses. Nevertheless, the initial price of orthoses and the training needed to use them effectively may be overwhelming.
The range of concerns that reduces acceptance and use of KAFOs and THKAFOs suggests several avenues of research. The number of well planned and properly conducted investigations is still very small. Increasing demand for evidence-based practice should result in more attention to orthotic research. Two complementary directions are of prime interest, namely measurement of energy consumption and gait velocity, under a wide range of ambulatory circumstances, and development of better designs.
Relatively feasible are studies of normal subjects wearing KAFOs with locked knee hinges, stance control orthoses, and orthotic designs. Early work involving healthy young men whose joints were immobilized must be expanded. The study samples should include people of various ages, particularly older adults, as well as both women and men, people of normal and excessive weight, and those of various ethnicities. If orthotic features have a different effect on various segments of the population, then prescription should reflect the differences. If the response to a particular type of orthosis is independent of age, gender, body weight, or ethnicity, then the orthosis can be prescribed more broadly.
To the baseline of conclusions from studies of unimpaired people should be added physiological studies of individuals with the disabilities generally treated with orthoses. The problem of recruiting homogeneous sample sizes large enough to enable detection of significant differences is formidable. Cross-over research designs partially address the issue. A national database of orthotic users and candidates is another way to obtain adequate study sizes.
Improvement in orthotic design is ongoing. Worldwide cooperation among designers and manufacturers is admirable. Nevertheless, much still needs to be done to enable every patient to achieve maximum function. Orthoses that are easier to fit and adjust initially and subsequently if the patient’s size or contours change would hasten rehabilitation, lessen the risk of skin lesions and other injuries attributable to the orthosis, and promote greater acceptance of orthoses. Exploration of lighter materials that retain requisite strength and durability would lead to orthoses requiring both less maintenance and faster, less expensive repair. Smoother, more efficient gait depends on the appropriate extent of stability in stance phase and adequate assistance for propulsion and swing phase clearance. Alternate knee joint designs should be developed to minimize irritative pistoning when the wearer ambulates. Although polycentric joints theoretically offer a better approximation of the motion of the anatomic knee and may be designed to be so stable as to make locking unnecessary, these joints have more moving parts, increasing the potential for needing more maintenance than is the case with single-axis hinges. Polycentric joints are also relatively heavy, bulky, and costly. Orthotic knee joints serve contradictory purposes. During walking, the anatomical knee moves in all three planes with a subtlety that no current mechanical knee joint duplicates. If the mechanical joint is unlocked, pistoning with shearing force is likely. If the mechanical knee joint is locked, the wearer incurs increased oxygen cost and sustains increased ground reaction forces.
Better designs should help patients move from sitting to standing more easily. Ratchet hinges do increase stability during the intermediate stages of transferring from a chair to upright posture; however, refinement of these hinges would be welcome. Another practical problem confronting people who wear lower-limb orthoses is maneuvering on threshold, stairs, ramps, and curbs, as well as mud, sand, and snow. While stability is essential for those with marked paralysis, overly stable orthoses make ambulating on surfaces other than level floors difficult or impossible. Although knee hinges can be adjusted to accommodate flexion contractures or limit the range of motion, further development could increase durability, reliability, and streamlined appearance.
Optimum physical therapy for the patient who is a candidate for a KAFO or other lower-limb orthosis involves thorough evaluation, rational recommendation of the orthosis, careful inspection of its fit and function, appropriate training in the full scope of ambulatory function, and teaching the patient to care for the skin and the orthosis. Under the best of circumstances, the patient accepts the orthosis and uses it whenever appropriate to achieve maximum function. Sometimes, however, the patient rejects orthotic intervention, when it is proposed, when the orthosis is delivered, or sometime afterward. Physiological, psychosocial, and practical problems bedevil the patient. Ongoing and expanded research can address some of the difficulties associated with wear and use of KAFOs and more extensive lower-limb orthoses.