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Area of general research interest:
Biomechanics of the Lower Extremity
Current program:
- Bone structure and response to external loading
- Shear and pressure measurement device
- New prosthetics technology for amputee patients
Investigators:
- Davis, Brian L., Ph.D.
- Hasasneh, Zaid, Ph.D. Candidate
- Lee, Dong-Gil (Andy), Ph.D. Candidate
- Noble, Lawrence, M.S.
- Tajaddini, Azita, D. Eng.
- Wozniak, Brandy, B.S.
- Yavuz, Metin, Ph.D. Candidate
Collaborators:
- Cavanagh, Peter, Ph.D.
- Bethoux, Francois, M.D., Dept. of Neurology, CCF
- Botek, Georgeanna, D.P.M., Dept. of Orthopaedic Surgery, CCF
- Grabiner, Mark D., Ph.D.
- Luciano, Mark, M.D., Dept. of Neurosurgery, CCF
- Richards, Kirsten, Dept. of Orthotics and Prosthetics, CCF
- Sahgal, Vinod M.D., Rehabilitation Medicine, CCF
- Sferra, James, M.D., Dept. of Orthopaedic Surgery, CCF
- van den Bogert, Antonie J., Ph.D.
Brief Description:
The research program in this area is directed towards developing a greater understanding of the human locomotor system. This research involves developing new technology to measure aspects of locomotion that have previously eluded investigators as well as studying the structure of normal and osteoporotic bone. Examples of devices that are being designed are (i) a device to simultaneously measure pressure and shear forces at specific sites under the feet of patients with distal periphery neuropathy; and (ii) prosthetic devices to enhance the ambulatory capabilities of amputee patients.
Bone structure and response to external loading
This NASA-funded research focuses on the relationship between external impact forces and internal strains that the bones of the lower extremity experience. It is well known that the internal structure of bones (i.e., trabecular architecture) is affected by the nature of loads that each bone experiences. When these loads are changes (as, for example, when an astronaut becomes weightless), the bones undergo rapid remodeling. At present, studies on the relationship between bone strength and trabecular architecture are being conducted. It is anticipated that this research endeavor will give insight into the effects of a disease such as osteoporosis. Future plans include the possibility of determining factors that are associated with Charcot foot fractures in diabetic patients.
Shear and pressure measurement device
Foot ulceration, a diabetic complication that is difficult to treat, results in significant morbidity and in many cases precedes limb amputation. It has been reported that 20% of all diabetic patients in hospitals have been admitted for foot problems. Previous research has established the significance of nerve damage and a compromised vascular system in the etiology of diabetic foot ulcers. In recent years, the importance of mechanical factors such as pressure and frictional forces has also been established, but to date, these two loading conditions have never been measured simultaneously. As a consequence, the true three-dimensional loads that are applied to the sole of the foot have never been quantified. The rationale behind the current research is that by (i) quantifying localized skin loads and (ii) obtaining noninvasive measurements of tissue properties, the factors leading to diabetic skin ulceration will be more fully understood.
New prosthetics technology for amputee patients
In the last decade there has been a trend for above-knee (AK) prosthetic designs to become more sophisticated. Generally, there are trade-offs between performance, cost, complexity, and weight. To date, no lightweight design has yet met all of the desired features of (i) stability during load bearing, (ii) controlled motion during the swing phase of gait, (iii) rapid changes in level of resistance as one moves from one phase of gait to another, and (iv) variable response of the system depending on the patient's cadence and/or walking speed.These limitations could possibly be addressed using hydraulic technology. Presently a joint research venture between the CCF and industry is aimed at designing an AK device that improves the ambulatory capabilities of amputee patients.
These limitations could possibly be addressed using hydraulic technology. Presently a joint research venture between the CCF and industry is aimed at designing an AK device that improves the ambulatory capabilities of amputee patients.
Mechanism of calcaneal fractures
Calcaneal fractures in the industrial patient are a common occurrence. Likewise, in military recruits, it has been reported that 84% (male) and 93% (female) of foot injuries following a drop landing have involved fractures of the hindfoot. In addition, during frontal motor vehicle crashes, calcaneal fractures may result from a superposition of the forces generated by the Achilles tendon attempting to plantarflex the foot and the floor pan or brake pedal dorsiflexing the ankle and then impacting the hindfoot. Seventy-five percent of these fractures are intra-articular. The purpose of the study is to resolve two schools of thought regarding the mechanism of intra-articular fractures. One involves vertical loading of the calcaneus by the talus at the "Gissane Angle," and the other involves eccentric loading of the talus on the calcaneus, with the sustentaculum tali being loaded as a cantilever.
Relationship between the site of initial soft tissue breakdown and internal stresses in forefoot plantar soft tissue
Diabetic foot ulceration is a complex problem that involves the response of the soft tissue on the sole of the foot to both external stresses (pressure and frictional forces) applied to the skin and internal changes (e.g., blood supply, nerve damage). There is increasing evidence that it is the combination of increased external stresses and changes in the properties of the soft tissue (fat, skin) that is of prime importance in the formation of foot ulcers. Considerable research has been directed at quantifying external stresses, such as the pressure on the sole of the foot during walking, but research in the area of soft tissue properties has lagged behind. Magnetic resonance imaging (MRI) techniques will be used to examine plantar soft tissue in diabetic patients who are most likely to require limb amputation.