The Leon Root, MD, Motion Analysis Laboratory

A gaitmat is a computerized walkway that records the characteristics of a patient's walking mannerisms (i.e. distance covered per step, average walking speed, etc.) The gaitmat is capable of real-time quantitative analysis of temporal and distance gait parameters. The surface of the walkway contains small switches arranged in rows. The switches are in an open position, when a subject walks across the mat the switches close and then reopen as the subjects feet come in contact and break contact with the mat.

When a switch closes and reopens, the computer records the closing and opening times. As a result, the temporal and spatial characteristics (stride length, double support time, step length, step time, average velocity, etc) of the patient’s gait are obtained.

Joint kinematics is the study of the positions, angles, and velocities of body parts/joints when in motion. The lab has a 14-camera motion capture system to collect 3D kinematic data in a volume approximately 4m x 10m x 2.5m. The system can be used to analyze joint motions in the body. Kinematics can be collected during walking and selected tasks in certain individuals.

Our large data capture area allows data capture for both clinical patients and research studies ranging from arm functioni to walking.

Joint kinetics refers to the forces transmitted by the motion of muscles, tendons, ligaments, and bones. To measure kinetics, four force plates measuring the ground reaction force are installed within an epoxy leveled and isolated 10’ x 14’ pit. Force plate technology is useful in both clinical and research applications as it allows us to see joint forces, powers, and limits. Allowing us to see how much force is acting on a patient’s joints; a useful piece of data to help compile a complete analysis.

The lab has an instrumental stair system which can be set up in our motion capture area and works in coordination with our force plates. The stair system allows us to capture a patient using stairs through our 3D motion capture system (allowing us to see the angles of movement) and the forces the patient exerts on their joints while they climb the stairs (allowing us to quantify the force the patients joints are encountering). 

Plantar pressure is a measurement that identifies and quantifies areas of high pressure (stress) in one's feet. The insole plantar pressure wireless system is designed to measure in-shoe pressures. Each insole contains an array of high quality capacitance sensors. In-shoe plantar pressure distribution assessment allows physicians to evaluate how various foot orthoses, braces, or shoe designs affect atypical loading under the feet.

The barefoot plantar pressure system is designed to measure the distribution of pressure on the barefoot while walking or standing. The system consists of a pressure plate, placed on the walkway, level with the floor.

The data obtained from the pressure plate can be analyzed using the equipped software to determine peak pressure, pressure time integral, and maximum force under different regions of the foot. In addition, a custom-developed program is used to calculate certain parameters of interest, including the Center of Pressure Excursion Index (CPEI), peak pressure, foot angle, and the temporal sequence of loading for three phases of stance.

Electromyography (EMG) is a medical technique used to evaluate and record the electrical activity produced by skeletal muscles. EMG electrodes are used in coordination with our motion capture system, allowing us to see which muscles are working properly. With the aid of EMG, abnormalities can be detected within the muscular system and how the muscles are working with the patient’s skeletal system. EMG’s are very useful for patients undergoing rehab (to track progress) and for patients with neuromusculoskeletal conditions (to better understand how our patients may be better treated). 

The lab has two isometric/isokinetic dynamometers to measure strength in the lower and upper extremities. They are used to test post-operative strength or changes in strength during the course of therapy. Our dynamometers are useful for quantifying muscle strength and allow us to systematically observe how well a patients muscle is functioning.

The Malleolar Valgus Index (MVI) is a static measurement taken with a flatbed computer scanner. An MVI value is helpful in categorizing the structure of a foot along a spectrum containing planus (flat-foot), rectus (ideally-aligned), and cavus (high-arched) feet.

To make an MVI measurement a plexiglass platform is placed over the flatbed scanner and a custom-made MVI jig is fitted to the medial malleolus and lateral malleolus (the ankle bones). A scan of the foot is then made in grayscale and posterized to eight levels which allows for a better view of the foot’s contact with the ground.

The first metatarsal phalangeal joint flexibility device is designed to measure the flexibility of the first metatarsal phalangeal joint. After securing the patient’s foot in the device, the operator rotates the plate secured to the big toe toward the top of the foot while moment and angle data are collected. The flexibility of the first metatarsophalangeal joint is estimated as the slope of the moment versus angle curve.

Arch heights are measured in order to characterize foot shape and foot structure. The measurement also allows us to compare these characteristics between a sitting and a standing position. A left and right device is used to measure the foot length and truncated foot length (foot length from the heel until the first metatarsophalangeal joint). The arch height is then measured from ½ the footlength with a free-falling bar.