1998 Research Accomplishments

Impacts - March, 1999

The Rehabilitation Research and Development Service (Rehab R&D) believes that the next century holds tremendous promise for clinical advances in rehabilitative care for veterans who suffer from disability or impairment. Progress made by researchers makes it possible to anticipate great strides in functional recovery and thus optimal independence for patients. An increasing arsenal of rehabilitative therapies that focus not only on adaptation but restoration is now a reasonable expectation.

Special Populations

Better understanding of muscle potentials will enhance nerve injury assessment.

A standard part of the clinical examination of patients with suspected nerve entrapment syndromes or demyclinating neuropathies involves stimulating a peripheral nerve and recording the electrical signal evoked in the innervated muscle. VA researchers at the Palo Alto Rehab R&D Center use cutting-edge computer simulations to gain new understanding of how these signals travel from nerves to muscles, and, consequently, spread throughout the limb. They recently demonstrated, for example, the pathway of electrical signals of hypothenar muscles in the hand from interosseous muscles several centimeters away. This discovery has important implications for the correct clinical interpretations of these signals - and for the diagnosis of patients with nerve entrapment syndromes and other nerve disorders.

McGill KC, Lateva ZC. The contribution of the interosseous muscles to the hypothenar compound muscle action potential. Muscle & Nerve 1998.

New tool provides more accurate bone loss information.

Research at the Palo Alto VA Rehabilitation Research and Development Center have produced new insights into the nature of bone loss in persons with spinal cord injuries and their consequent higher risk of fractures. Therapies for preventing and reversing bone loss can be evaluated with a standard clinical CT imaging system in combination with computer algorithms for bone registration and beam hardening corrections. This tool has the potential to provide the most accurate information to date on the loss of bone mass in individuals with SCI and osteoporosis. In a parallel study, a method for increasing bone fracture resistance through the repeated application of low-magnitude trauma forces was developed and recently patented. More work needs to be done to prevent fractures; VA research has shown that although reduced bone mass is a significant risk factor for patients with spinal cord injury, it is not the only one.

A501-4R and A2014-R

Chronic Diseases

New bonding agent makes orthopedic implants stronger.

The primary problem found in cemented hip implants is debonding at the implant-cement interface. This leads to cracks around the implant and subsequent cracking through the cement mantle to the bone. Researchers at the VA Palo Alto Rehab R&D Center and Stanford University have found a way to strengthen the bond using a unique silane coupling agent that chemically bonds bone cement to an orthopaedic implant alloy. Hip implants coated with the new coupling agent were up to 170 percent stronger than uncoated controls in laboratory testing. For hip replacement patients, this breakthrough promises implants with longer life spans and, therefore, less chance of future surgeries.

Paal AF, Yerby SA, Young PM, Beaupre GS, and Goodman SB. The Effect of a Silane Bonding Agent at the Bone Cement-Implant Interface. Transactions of the 45th Orthopaedic Research Society 1999; p. 122.

Yerby SA, Young PM, Beaupre GS, Pool AF, and Goodman SB. The Effect of a Silane Coupling Agent on the Bond Strength of Bone Cement and Cobal-Chromium Alloy. 1st National VA Rehabilitation Research and Development Meeting, 1998, P111.

Post-stroke patients with hemiplegia benefit from strenuous exercise.

A new study by researchers at the VA Palo Alto Rehab R&D Center challenges the conventional belief that patients with post-stroke hemiplegia should refrain from strength training exercise. Muscular weakness can be a serious problem for post-stroke patients with hemiplegia, or paralysis that affects only one side of the body. But few of these patients are prescribed a strength training regimen because of the widely held view that this type of exercise increases spasticity. In the VA study, 15 patients with post-stroke hemiplegia pedaled an exercise bicycle at different workloads. The researchers found that, at higher workloads, the patients were able to produce greater forces with their functional leg - without increases in movement dysfunction. These results suggest that strenuous exercise such as bicycle pedaling at higher workloads can have a positive effect on people with post-stroke hemiplegia.

Brown DA and Kautz SA. Increased workload enhances force output during pedaling exercise in persons with post-stroke hemiplegia. Stroke 1998; 29: 598-606.

Aging

VA designs new system to diagnose and reduce risk of falls.

VA researchers are developing a state-of-the-art system to reduce the number and severity of fall-related injuries while increasing the mobility and independence of older veterans. This advanced accelerometric motion analysis system will assess balance and impairment in patients who are at risk for falls, help formulate individual therapies, and monitor patient progress. Currently, the VA is enlisting the support of a commercial partner to develop this technology further. Potential commercial applications of this system include clinical diagnosis of nursing home and hospital patients' fall risk, as well as athletic and occupational injury prevention and rehabilitation.

E2182-DA