Gait Analysis in Lower-Limb Amputation and Prosthetic Rehabilitation

Gait analysis combined with sound clinical judgment plays an important role in elucidating the factors involved in the pathologic prosthetic gait and the selection and effects of available interventions to optimize it. Detailed clinical evaluation of walking contributes to the analysis of the prosthetic gait, but evaluation in the gait laboratory using kinetic and kinematic data is often necessary to quantify and identify the particular contributions of the variables impacting the gait with confidence and assess the results of such intervention. The same approach can be considered when selecting prosthetic components and assessing leg length in this patient population.

Key points

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Optimizing the gait characteristics of a person who underwent amputation can enhance the cosmetic qualities of the gait, influence residual limb comfort, and impact the efficiency of ambulation.
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To adequately evaluate the gait characteristics of a person with lower-limb amputation a keen understanding of normal gait, and the possible gait deviations is necessary.
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Biomechanical knowledge of gait and prosthetics is needed to provide optimal clinical care.

Optimizing the gait characteristics of a person who underwent amputation can enhance the cosmetic qualities of the gait pattern; but more importantly, it can also influence residual limb comfort and may affect the efficiency of ambulation and reduce compensatory movements that, over time, may prove damaging to individuals. Gait quality and its velocity can be used as outcome measures in this population.

To adequately evaluate the gait characteristics of people with lower-extremity amputations, the clinician must have an understanding of the normal gait as well as the “typical gait deviations” frequently exhibitied by individuals with limb amputation. With this background, specific gait abnormalities can be identified and compared with a catalog of known gait abnormalities to identify the possible contributing factors and available interventions from sound biomechanical knowledge to provide the basis for clinical interventions.

The most common cause of an abnormal gait pattern in people with lower-extremity amputations is inadequate prosthetic alignment. The angular and translational position of the socket in relation to the pylon and foot is an important determinant of the walking pattern. Leg length discrepancies, either true or related to a less-than-optimum position of the residual limb within the socket or inefficient suspension, are important secondary causes of gait abnormalities for this population.

Clinicians who care for individuals with lower-limb amputation must develop a high level of competence in observational gait analysis. Observational gait analysis in a person who underwent amputation is a form of clinical evaluation that requires skill and practice; by observing the motion of the body segments and comparing it with known abnormalities and their underlying mechanisms, one cannot only assume the cause of the abnormal pattern of motion but also develop a corrective strategy and use an iterative process to observe an improvement.

Ultimately, the goal of clinical gait analysis is to optimize the kinematic pattern of the gait so that patients walk as normal as possible. There has been debate in the literature as to whether or not a normal kinematic pattern is necessarily the best or the most efficient gait pattern for individuals with various disabilities; that is, it may be theoretically advantageous for a person who underwent amputation to walk with a kinematic pattern that is different from normal (a compensation) to improve the biomechanical performance of a prosthetic device. Of importance is the desire of many individuals with disabilities, including those with limb amputation, to minimize any external appearances of disability. So even though there may be a metabolic or other disadvantage to a normal-appearing gait, the psychosocial advantages of a normal-appearing gait may far outweigh the relative importance of other considerations.

The human gait is complex, and its fundamental objective is to move safely and efficiently from one point to another. This objective is accomplished by using a cyclical and highly automated movement pattern, with rhythmic, alternating motions of the trunk and extremities that ultimately move the center of mass forward.

Computerized gait analysis involves the reduction of this continuous process into several defined parameters for quantification, evaluation, and comparison. Gait analysis at different times in the rehabilitation process can be useful in the evaluation and optimization of the gait of individuals with lower-limb amputation. In the author’s institution, it is particularly helpful in monitoring the progression of rehabilitation; the effectiveness of a particular intervention or for prosthetic component selection; and in the hands of experienced clinicians, for providing detailed information that is useful in the quantification and assessment of prosthetic alignment adjustments with the goal of gait optimization.

Normal locomotion

From a clinical standpoint, it is important to understand the events of the walking cycle. Functional locomotion is concerned with simultaneously solving 5 basic motor problems: (1) the generation of mechanical energy for controlled forward progression, (2) absorption of mechanical energy to minimize shock and/or to decrease the forward progression of the body, (3) the maintenance of a stable upright position, (4) support of the upper body on the lower limb during the stance phase, and (5) control of the lower-extremity position to assure appropriate articulation with the ground during the stance phase and clearance of the foot during the swing phase.

Under normal conditions, comfortable walking speed corresponds to the speed at which the energy cost per unit of distance is minimized. Achievement of energy efficiency depends on unrestricted joint mobility and the precise timing and intensity of muscle action. Abnormal gait biomechanics result in increased energy utilization, usually with a compensatory decrease in walking speed. Often, the compensatory movements necessary for ambulation can produce exaggerated displacements of the center of gravity, which result in increased energy expenditure. Patients with lower limb amputations who have a normal cardiopulmonary mechanism and nutritional status do not ordinarily expend more energy per minute than able-bodied persons, although the energy required per unit distance is increased.

Impaired balance, sensation, and problems with limb clearance can contribute to the anxiety of ambulation and may increase the frequency of loss of balance and falls, a common clinical complaint of this patient population at least in the initial gait-recovery period.

Normal locomotion

From a clinical standpoint, it is important to understand the events of the walking cycle. Functional locomotion is concerned with simultaneously solving 5 basic motor problems: (1) the generation of mechanical energy for controlled forward progression, (2) absorption of mechanical energy to minimize shock and/or to decrease the forward progression of the body, (3) the maintenance of a stable upright position, (4) support of the upper body on the lower limb during the stance phase, and (5) control of the lower-extremity position to assure appropriate articulation with the ground during the stance phase and clearance of the foot during the swing phase.

Under normal conditions, comfortable walking speed corresponds to the speed at which the energy cost per unit of distance is minimized. Achievement of energy efficiency depends on unrestricted joint mobility and the precise timing and intensity of muscle action. Abnormal gait biomechanics result in increased energy utilization, usually with a compensatory decrease in walking speed. Often, the compensatory movements necessary for ambulation can produce exaggerated displacements of the center of gravity, which result in increased energy expenditure. Patients with lower limb amputations who have a normal cardiopulmonary mechanism and nutritional status do not ordinarily expend more energy per minute than able-bodied persons, although the energy required per unit distance is increased.

Impaired balance, sensation, and problems with limb clearance can contribute to the anxiety of ambulation and may increase the frequency of loss of balance and falls, a common clinical complaint of this patient population at least in the initial gait-recovery period.

Gait analysis

Clinicians routinely do informal, visual analysis of gait in patients with leg amputation. This type of analysis does not provide quantitative information and has many limitations because of the speed and complexity of human locomotion. This circumstance is further complicated by the gait deviations and compensations present in the walking pattern of individuals with lower limb amputation. Gait can be studied through the collection of a wide range of quantitative information in the laboratory using optoelectronic technology and force platforms. In the author’s laboratory, they use 3 infrared Coda CX1 (Charnwood Dynamics, Leicester, UK) active marker units and 5 specially designed force platforms ( Fig. 1 ). A major advantage provided by these system is the speed of data acquisition and processing, which is essential to allow for the efficient use of the clinician’s and patients’ time for the effective assessment and intervention of the subject under evaluation. For patients whereby running assessment is the goal, an instrumented treadmill with 2 force platforms that have independent velocity control for each leg is available in highly specialized centers ( Fig. 2 ).