December 2009

CP gait studies document AFO efficacy

By Linda Weber

Clinicians who treat ambulatory cerebral palsy patients rely heavily on ankle-foot orthoses, which are the most effective treatment option for improving gait mechanics. But because CP encompasses such a wide range of symptoms, selecting the most appropriate corrective brace for a patient’s specific gait abnormality or abnormalities can present clinical challenges. Recent studies that shed light on ankle-foot orthoses’ impact on gait are characteristic of crucial ongoing research.

A study in the February 2009 issue of the Journal of Children’s Orthopedics found that AFOs improve spatio-temporal gait parameters and gait stability in children with spastic CP, but have a lesser effect on proximal joint kinematics. It also concluded that children with spastic hemiplegia show  greater improvement from AFOs than those with spastic diplegia.

The investigators used three-dimensional gait analysis to evaluate the impact of AFOs in 56 children with cerebral palsy. In the hemiplegic group, stride length on both sides was 11.7% longer with AFOs than while barefoot, cadence was reduced by 9.7%, and walking speed was not affected. In the diplegic group, stride length with AFOs was 17.4% longer compared to barefoot, walking velocity improved by 17.8%; and cadence was unchanged. In addition, participants in both groups experienced increased dorsiflexion. And in the hemiplegic group, knee flexion decreased, whereas in the diplegic group the investigators found no influence.

In the October issue of the Journal of Bone Joint Surgery (American), researchers from  Greenville, SC, determined that the efficacy of a floor reaction ankle-foot orthosis in children with CP may depend on the degree of joint contracture. They analyzed both barefoot and braced gait in 27 subjects with a crouch gait pattern, characterized by increased ankle dorsiflexion, increased knee flexion, and increased hip flexion in stance phase.

“Our study showed that the FRAFO is effective at controlling crouch gait in children with hip and knee flexion contractures of 10° or less. Contractures of 15° or greater at the hip or knee should be corrected by therapy or surgery prior to the use of the FRAFO,” said  Jon Davids, MD, chief of staff and medical director of the Motion Analysis Laboratory at Shriners Hospital for Children in Greenville.

A study in the February 2009 issue of the Journal of Bone Joint Surgery (American) found no significant difference between hinged and dynamic AFOs for improving gait and motor function in children with spastic diplegic CP who exhibit a jump gait pattern. The researchers compared 15 CP patients to 20 children with normal gait.

In the July 2008 issue of the Journal of Rehabilitation Medicine, researchers found that AFOs improved walking efficiency compared to a barefoot condition in 54 children with spastic quadriplegic CP. However, energy cost did not change significantly between conditions in 21 children with spastic hemiplegic CP or 97 children with spastic diplegic CP.

At the March annual meeting of the Gait and Clinical Movement Analysis Society, Canadian researchers presented a case study illustrating how 3D motion capture technology can determine the appropriateness of an AFO for children with specific gait abnormalities.

Those investigators say advances in technology will soon benefit both researchers and clinicians.

“I think computer modeling has made and will continue to make significant contributions to our understanding of ‘normal gait’ as well as to the biomechanical and neuromuscular impact of various AFOs on gait,” said Kyra Kane, BscPT, a physiotherapist at the University of Regina.

Wearable sensors and improved 3D motion-analysis technology may also have a transformative effect on gait research, said John Barden, PhD, assistant professor of kinesiology and head of the Neuromechanical Centre at the university.

“I do think these technologies to some degree are the wave of the future, but only as tools that add value to an existing process that often works well,” Barden said. “Sensors have the capacity to provide large amount of data  that far exceed what can be done in the lab.”

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