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As an individual walks, the position of each joint constantly changes. The motions of these joints are computed from the measured positions of a number of reflective markers placed on either arms or legs, and on the pelvis. These positions are recorded by our 10 special electronic/digital cameras, capturing all body positions at 120 frames per second.

The cameras track the position of the markers while moving. The positions are stored in the computer. Then, with a program we ¡°connect the dots¡± to determine and quantify the motion of each body segment. Quantification means that we calculate the exact positions and joint angles of interest.

Please note, the markers are taped directly onto skin with special medical tape to avoid skin reactions.

Overall performance assessment includes measurement of walking speed, length of each stride, length of each step and number of steps taken per minute. The time that each leg spends on and off the ground (that is, supporting the body and swinging) are also important factors that we observe. Differences as little as several hundredths of a second are identified ¡ª and can be important to determining a patient¡¯s mobility needs.

During walking, individual muscles are monitored to record when they are active with the use of little ¡°microphones¡± called electrodes. The recordings focus on the times at which each muscle turns ¡°on¡± (begins to contract) and turns ¡°off¡± (ends its contraction). Abnormal muscle activity can contribute to abnormal motion.

The muscle recordings allow us to evaluate the coordination patterns a patient uses to perform the activity. These recordings are made by placing surface electrodes on the skin over the muscles of interest. Before placing electrodes, the skin at the electrode locations is wiped with an alcohol pad to ensure ¡°clean¡± recordings.

Routinely, 10-12 muscles are monitored at the same time. A well-trained specialist or clinician affixes each of the surface electrodes to the skin at the appropriate anatomical location to ensure accuracy of their signals.

Recorded ¡°on¡± and ¡°off¡± times are compared with what we perceive to be normal for the activity performed.

For the walking trials, the loads that tend to cause rotation of the joints (or ¡°joint torques¡±) are computed. The torque reflects the loads generated by or placed on the muscles and passive tissues (like ligaments and joint surfaces). Joint torques are calculated mathematically by incorporating measurements of forces between the foot and ground (using load cells) with motion measurements. In combination with motion and electromyographic recordings, torques can be used to estimate energy costs associated with walking.

Detailed assessment of the pressure distribution at the sole of the foot is provided by this test. An impression of the foot is produced, which displays different degrees of pressure demarcated by different colors. A color computer display of the weight shift over time is available as part of this test. This is reduced to a graphic display of pressure-per-unit time at all key points of the foot for ease of inclusion in the patient¡¯s report. Diminished or increased pressures can easily be visualized and are specifically quantified.

The computerized footprint of the patient during walking is superimposed over a regular picture of the patient¡¯s foot to allow better visualization of the way the pressures are being distributed across different areas of the foot.

For patients who are not referred to us by physicians, we will obtain medical history and perform a physical evaluation. The physical exam includes:

• Range of Motion: This helps to determine if any tightness, obvious weakness or lack of coordination is present ¡ª all of which may contribute to problems with walking. This typically takes approximately one hour. It includes all motions of the hip, knee, ankle and foot on both legs. A range-of-motion examination is performed on the upper extremities if the patient¡¯s disorder affects these areas, and the focus of the motion analysis is an upper-extremity evaluation. The range-of-motion exam is necessary to allow interpretation of the data.
• Manual Muscle Exam: This includes all major muscles crossing the hip, knee and ankle joints on both legs. Examination of the upper extremities are included if the patient¡¯s disorder affects these areas, and the focus of the motion analysis is an upper-extremity evaluation. Grading of muscle strength is based on voluntary muscle effort and quantification using the standard Manual Muscle Grade (MMG) scoring system (5 = normal; 4 = good; 3 = fair but able to lift against gravity; 2 = poor and unable to lift against gravity; and 1 = trace ¡ª there is no movement, but muscle contraction can be felt with palpation).

All of the motion data derived from testing requires interpretation to reveal the cause (or causes) of the deficits and to suggest appropriate treatment. To do so, the information from many different walks is reviewed. This is necessary to ensure that the information examined represents a typical walk of the patient and to compare several different walking conditions (e.g., barefoot, with braces, assistive devices or shoe inserts). A comparison may also be needed to understand the change in a patient¡¯s pattern of walking on different dates before and after treatment. In all cases, the information obtained is compared to values from typically developed age-matched individuals.

Interpretations include summaries of primary, secondary and compensatory gait deviations. Primary deviations describe those deficits that are associated with a patient¡¯s primary pathology. Secondary deviations refer to those gait deficits associated with limb segments or joints that are not primarily pathologic, but whose motions are coupled to segments or joints with primary motion deviations.

Compensatory deviations are those motion patterns exhibited by a patient to compensate for one or more gait deviations at other locations. These interpretations of computerized walking data are analogous to interpretations of X-ray images that describe the severity and complexity of fractures, types of lesions or skeletal deformations. Like X-ray interpretations, gait data interpretations are isolated from evaluations of prognoses or recommendations for interventions.  However, ultimately, the gait interpretations are used for recommended plan of care actions.

Interpretation of the data takes place during our patient review sessions. A patient review session is a team approach that involves all members of our laboratory team, including trained physicians; engineers; kinesiologists; and physical therapists for the gait analysis or an occupational therapist for the upper-extremity motion analysis. During each patient review, all information ¡ª including the medical history, physical exam and the laboratory data ¡ª is used in assessing aspects of the patient¡¯s pathology that most hinder walking or upper-extremity function; making treatment decisions (e.g., surgery, bracing, orthotics, physical therapy, etc.); evaluating the patient¡¯s overall prognosis; and determining the effectiveness of previous treatments.

The outcome of the review of each patient is included in a written report that is forwarded to the referring physician. The report includes all motion analysis observations and recommendations for further treatment. Each written report is accompanied by a CDROM. The disk includes the graphical representation of all the information collected during the motion study and animations of the movement patterns of the patient.

If you are a patient ready to make an appointment for computerized motion analysis, please call us at 312.238.1447. If you are a physician looking to refer a patient, please visit our page for clinicians for referral information or to fill out our .