Gait Analysis: Simply Just One Foot in Front of the Other

  One of the most enthralling aspects of human locomotion is the uniqueness of each person’s gait. We see this depicted in novels and movies whether it be the bowlegged rolling gait of the cowboy or the smooth gazelle like stride of a dancer. As healthcare professionals, we clue into the festinating pattern of a person with Parkinson’s disease or the antalgic gait of an arthritic patient. While a student in Physical Therapy school, I remember sitting for hours with classmates at a restaurant or in the mall, analyzing human gait; debating stride length, stance and swing phase as well as heel strike and toe off, all the while trying to determine musculoskeletal weakness and variances. Wound care practitioners have researched and debated the value of laboratory and observational gait analysis when considering our patients with diabetes and the manifestations of the disease that lead to foot ulceration. What is the benefit of formal gait analysis in the wound center?

  This author questioned two experts in the field: James A. Furmato, DPM, PHD, Chief Engineer, Gait Study Center and Assistant Professor, Temple University School of Podiatric Medicine, Philadelphia, Pa. and Jim Birke, PT, PhD, CPed, Director Rehabilitation Services, LSU Health Sciences Center, Diabetes Foot Program.

  VS: What types of gait analysis techniques are used in your lab?
  Dr. Furmato: The Gait Study Center uses equipment to provide objective assessment of gait and posture. The equipment allows our faculty and students to extend their clinical capabilities, assess mechanical properties of footwear, and provide educational material for physicians and patients.

  The plantar pressure sensing Emed and Pedars systems (both by Novel, Munich, Germany) are the most obvious of our devices in the GSC for identifying risk of developing an ulcer. The Emed system is embedded in our 52-foot long walkway and the Pedars is inserted into a shoe.

  Also embedded is a set of GaitMat plates (E.Q., Inc, Chalfont, PA). These measure footfall parameters and determine the overall sequencing of gait. At the center of the walkway are two force plates (Kistler Instruments, Amherst, NY) providing 3-D ground reaction force vectors joined with a 3-D kinematic system (Vicon, Oxford, UK). This coupled system determines how the forces delivered to the sole during gait are distributed throughout the body.

  Foot structure is assessed with homegrown devices: arch height index and malleolar valgus index. The arch height index device and a toe flexibility device determine soft tissue properties. A photoelectric gate system determines average forward velocity. An InFoot scanner (I-Ware Laboratory, Osaka, Japan) collects a detailed three-dimensional (3D) surface scan of the foot.

  We use a vibration perception threshold tester and 10-gram monofiloament to determine neuropathy. Digital still and video cameras record images and movement patterns for qualitative findings. We also have a treadmill for runners and where longer walking effects are of interest.

  Just as important to us are the software tools we use to extract information from the data produced by our equipment: LabVIEW, Matlab, Visual3d, Dartfish and JMP to name a few. We also have wireless electromyography (16 channel; Delsys, Boston, MA), accelerometers and contact switches to add to our understanding of human locomotion.

  VS: This equipment sounds very sophisticated and designed specifically for objective gait analysis performed in a laboratory. Are there systems or equipment better suited for an outpatient wound clinic?
  Dr. Furmato: The pressure measuring devices made by Tekscan, MatScan and Fscan (an insole device), are more appropriate to a clinical setting and are less expensive. Non-electronic pressure systems, such as the Visual Footcare Technologies’ PressureStat, cost a dollar or two per sheet but provide personal pressure distribution information that correlates well to the maximum peak pressure information produced by our Emed plate. Some clinics use a Nintendo WiiFit system for some light analysis. New capabilities are researched and developed for gaming systems and handheld smartphones to help track motion and applied forces.

  VS: What are the estimated capital costs for this equipment and are there routine costs to the facility when using this technology?
  Dr. Furmato: The combined capital costs for our Gait Study Center exceeds $500K US. There are lower cost systems with similar functions. Plantar pressure systems are available for a low rental fee or for free from some companies on condition they be used to order or dispense a product such as shoes, insoles or orthotics.

  Clinical gait analysis takes up space. You need room for a person to walk freely and achieve a natural gait. A walkway of about 10 meters is used in many centers for research. In collecting 3-D kinematics, several cameras must be mounted far enough away to “see” a volume of space 4mx2mx2m from above. This room would be about 12mx12mx3m for data collection. This does not reflect office space, a clinical examination area, and restroom/changing area. It’s a big space, hard to find and hard to put a price tag on when starting new. A proposal from 10 years ago for a new gait analysis facility built as a new floor over the Foot and Ankle Institute was priced at over $2M US.

  VS: Is gait analysis reimbursable in an outpatient department?
  Dr. Furmato: To be reimbursable, the facility must be associated with a healthcare institution like a hospital or university. A visit for clinical gait analysis including a history and physical exam with expanded arthrometric and anthropometric data collection can take over two hours. Add 3-D kinematics and the visit can approach three hours. A gait laboratory with one operator may be able to process one patient at a time and see three or four in a busy day.

  With two operators, throughput may increase. For example, in one study, with two operators, we processed three subjects in the time available for two. In other studies, we averaged two in the time space of one.

  To be reimbursed, there are required studies to perform. Plantar pressures, 3-D kinematics and qualitative video may reimburse at under $500. It’s safe to say recouping the investment is difficult within five years. A long-term commitment for space and funding is essential to maintain a gait facility.

  VS: Should this be a routine diagnostic tool for patients with diabetic neuropathy?
  Dr. Birke: I am not sure there is an important role for routine gait analysis (beyond observational gait analysis) in the prevention of foot ulceration. Laboratory gait analysis, however, is certainly valuable in research on the diabetic foot.

  Dr. Furmato: Ongoing research, at facilities like the TUSPM GSC, continues to look for the connection between walking and ulcergenesis. At this time, however, it is not a good predictor of ulceration.

  Dr. Birke: The question is how can we prevent foot ulceration in individuals with diabetes? Foot ulcers are primarily a neuropathic complication of diabetes. Loss of protective sensation, deformity and muscle weakness associated with neuropathy is associated with high pressure and injury to the foot. Injuries in the insensate foot are caused by direct trauma (ie, stepping on nail), constant low pressure (ie, tight shoe or heel pressure in bed), but most commonly repetitive walking stress over high-pressure areas on plantar aspect of the foot. The primary gait abnormality associated with these injuries and their failure heal is a non antalgic (abnormal normal) gait. An individual who has an insensate foot and plantar ulcer will walk repeatedly and without a limp on the injured foot because of the absence of pain. That said, patients often display deformities and gait abnormalities, which can contribute to foot injuries (including claw toes, hallux limitus, uncompensated rearfoot varus, excessive pronation, equinus, foot drop, poor balance/gait instability etc.), and accommodating footwear for these deformities and gait abnormalities may be helpful in reducing foot stress.

  Dr. Furmato: I would recommend using some form of gait analysis in patient education. I believe many individuals would deny a bad outcome is likely to occur for them unless you know it occurred in a very close relative. Presenting the personal plantar pressure map for someone in the context of a diabetic foot education program may not be diagnostic, but it may be preventative. I’d rather reduce the occurrence of a bad outcome than predict a problem that I can’t prevent!

  Dr. Birke: Clinicians need to perform foot screens and risk assessments on all individuals with DM, provide scheduled follow-up to promote prevention strategies, prescribe shoes customized to offload high stress areas on high risk feet, see patients promptly for the treatment of early injuries/ulcerations, aggressively offload injuries/ulcerations to promote healing and monitor the progression of activities after ulcer healing. These activities should be part of a comprehensive diabetes prevention and treatment program, administered by a multidisciplinary rehabilitation team, including physical therapists in a primary role.

Conclusion

  Gait analysis is frequently used in Podiatry and Rehabilitation Clinics primarily for orthotic and foot wear evaluation and fabrication. Formal gait analysis demonstrates great research benefit for understanding musculoskeletal changes that are often seen in diabetic as well as other patients that may lead to injury. Less expensive pressure measuring devices assist in education of the patient as well as being a simpler means to provide appropriate foot wear and off-loading for patients with gait disturbance or abnormality. On going research will continue to pursue the relationship between musculoskeletal deformity and the neuropathic patient leading to ulceration.

  Val Sullivan is a physical therapist and a board Certified Wound Specialist through the American Academy of Wound Management. She is the Clinical Manager of Advanced Wound Care Services and Hyperbaric Medicine at Capital Regional Medical Center in Tallahassee, FL. A clinician and educator in Wound Management, Val has lectured and presented on local, regional and national levels as well as publishing articles on wound care and education.

  As a member of the American Physical Therapy Association (APTA) and its Section on Clinical Electrophysiology and Wound Management, Val is on the Consulting Group for the Integumentary section of Hooked on Evidence. She has been an active member of the Association for the Advancement of Wound Care, serving on the Quality of Care Task Force. She is also a member of multiple Clinical Advisory Boards and is on the Board of Directors for the Save A Leg Save A Life Foundation. An unabashed oenophile, Val co-founded the Wound Care Wine Club to assist Wound Care professionals in the North Florida/South Georgia area with networking, education and marketing.