Impairment of electrical activation of wrist flexor and extensor muscles during gripping and functional activities in the early stage of hand osteoarthritis: A cross-sectional study

• Published in: Journal of hand therapy 2021-01, Vol.34 (1), p.109-115
• Main Authors: Tossini, Natália Barbosa, Lessi, Giovanna Camparis, Simões Zacharias, André Luís, Corrêa e Silva, Gabriella Regina, Seraphim Abrantes, Luiza Souza, Mendes da Silva Serrão, Paula Regina
• Format: Article
• Language: English
• Subjects: Arthritis; Biomedical materials; Cross-sectional studies; Cutting tools; Data collection; Electrodes; Electromyography; Flexors; Grip strength; Hand; Hand (anatomy); Hand strength; Impairment; Motor units; Muscle contraction; Muscles; Osteoarthritis; Pain; Physical functional performance; Questionnaires; Signal processing; Statistical analysis; Wrist
• ISSN: 0894-1130; 1545-004X
• DOI: 10.1016/j.jht.2019.12.010

This is a cross-sectional study. The wrist extensor muscles have a fundamental role in the stabilization of the wrist while performing manual activities. However, it is unknown if the clinical signs of hand osteoarthritis (HOA) cause impairment in the activation of these muscles The purpose of this study was to investigate whether early-stage HOA affects the magnitude of activation and coactivation between the wrist extensor and flexor muscles Thirty-two subjects were divided into two groups: control group (n = 16; 55 ± 7.42 years) and a group with HOA grades 2 or 3 (HOAG; n = 16; 57 ± 7.82 years). Muscle activation was measured in m. flexor digitorum superficialis, m. flexor carpi ulnaris (FCU) and extensors (EXT) during the evaluation of grip strength and three manual activities (write, cut a paper with scissors, and close and open a bottle). The coactivation index was calculated between the electromyography of the flexors (FCU and FSD) and wrist EXT. HOAG presented reduced muscle activation in all tasks, with a statistical difference for the flexor digitorum superficialis and EXT in the scissors activity, and for the FCU in the bottle activity. No differences were found between groups for the coactivation index and grip strength. The reduced muscle activity may be due to an inability of the patients of the HOAG to recruit all motor units or to an inhibition related to the presence of pain. In the early stages of HOA, there is a functional deficit associated with a reduced muscle activity of the wrist muscles during manual activities. This cross-sectional study determined that•Hand osteoarthritis in the initial stages may contribute to the activation deficit of the flexor and extensor muscles of the wrist.•Hand osteoarthritis in the initial stages has a negative impact on hand function.•There is a functional deficit in this population with no change in maximum grip strength in the initial stages of the disease.