New clinical biomarkers related to locomotor performance, gait stability, gait pattern, and falls in adults with late-onset Pompe disease (LOPD) have been identified in a study published in the Journal of Neuromuscular Diseases.
The main determinant of gait stability, locomotion, and gait pattern in the study was the strength of a patient’s hip abductor muscles, however, weakness of the hip flexor muscles was the main factor influencing abnormal kinematics specific to the hip and knee. The percentage of time spent in the single support phase of the gait cycle, including both the mean and variability, was the largest determinant of falls.
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“The identification of these essential new clinical parameters leads us to recommend the systematic assessment of hip abductor strength and single support phase duration during gait in adults with LOPD using instrumented tools,” the authors wrote.
During the study, adults with LOPD had significantly weaker muscles of the lower extremity when compared to healthy controls using an isokinetic dynamometer. The maximum strength of the hip and knee muscles tended to be roughly half that of the healthy control group on average (all P ≤.001). The mean forces for the plantar flexors and dorsi flexors of the patients with LOPD were around 71.5% of controls.
In terms of locomotor performance, adults with LOPD had a decreased gait speed, shorter distance achieved during the 6-minute walk test, and a longer Timed Up and Go (TUG) test. Patients with LOPD also had more frequent falls and decreased average percentage of the gait phase in single-support but a higher variability in the percentage of the single-support phase. Increased pelvic drop, hip and pelvic instability, and knee flexion at foot strike were also observed in the patients with LOPD.
Stepwise multiple regression results revealed that the largest determinants of locomotor performance were hip abductor strength and plantar flexor strength. The number of falls was most related to a decreased mean value of the single support phase in conjunction with a higher variability in the single support phase of gait.
Both of these factors were influenced by hip abductor strength. In terms of gait pattern, changes in pelvic movement were primarily influenced by lower hip abductor strength, and to a lesser extent plantar flexor strength, while hip and knee gait changes were most influenced by hip flexor strength.
In the study, a total of 18 adults with LOPD and 20 healthy controls were enrolled. All patients underwent 3D gait analysis, muscle strength testing with an isokinetic dynamometer, and locomotor performance testing.
Maulet T, Cattagni T, Dubois F, Roche N, Laforet P, Bonnyaud C. Determinants and characterization of locomotion in adults with late-onset Pompe disease: new clinical biomarkers. J Neuromuscul Dis. Published online September 8, 2023. doi:10.3233/jnd-230060