Measuring postural control during mini-squat posture in men with early knee osteoarthritis.
Studies have suggested a compromised postural control in individuals with knee osteoarthritis (OA) evidenced by larger and faster displacement of center of pressure (COP). However, quantification of postural control in the mini-squat posture performed by patients with early knee OA and its relation to muscle strength and self-reported symptoms have not been investigated. The main aim of this cross-sectional, observational, controlled study was to determine whether postural control in the mini-squat posture differs between individuals with early knee OA and a control group (CG) and verify the relation among knee extensor torque (KET) and self-reported physical function, stiffness and pain. Twenty four individuals with knee OA grades I and II (OAG) (mean age: 52.35±5.00) and twenty subjects without knee injuries (CG) (mean age: 51.40±8.07) participated in this study. Participants were assessed in postural control through a force plate (Bertec Mod. USA), which provided information about the anterior-posterior (AP) and medial-lateral (ML) COP displacement during the mini-squat, in isometric, concentric and eccentric knee extensor torque (KET) (90°/s) through an isokinetic dynamometer (BiodexMulti-Joint System3, Biodex Medical Incorporation, New York, NY, USA), and in self-reported symptoms through the WOMAC questionnaire. The main outcomes measured were the AP and ML COP amplitude and velocity of displacement; isometric, concentric, and eccentric KET and self-reported physical function, stiffness and pain. No significant differences were found between groups for postural control (p>0.05). Significant lower eccentric KET (p=0.01) and higher scores for the WOMAC subscales of pain (p=<0.001), stiffness (p=0.001) and physical function (p<0.001) were found for the OAG. Moderate and negative correlations were found between the AP COP amplitude of displacement and physical function (ρ=-0.40, p=0.02). Moderate and negative correlations were observed between the AP COP velocity of displacement and physical function (ρ=0.47, p=0.01) and stiffness (ρ=-0.45, p=0.02). The findings of the present study emphasize the importance of rehabilitation from the early degrees of knee OA to prevent postural instability and the need to include quadriceps muscle strengthening, especially by eccentric contractions. The relationship between the self-reported symptoms and a lower and slower COP displacement suggest that the postural control strategy during tasks with a semi-flexed knee should be further investigated.
Department of Physiotherapy, Federal University of Sao Carlos, Rodovia Washington Luís km 235 - SP-310, São Carlos, SP 13565-905, Brazil. Electronic address: ma.petrella@gmail.com.
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Petrella
Department of Gerontology, Federal University of Sao Carlos, Rodovia Washington Luís km 235 - SP-310, São Carlos, SP 13565-905, Brazil. Electronic address: kagramanis@yahoo.com.br.
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Gramani-Say
Department of Physiotherapy, Federal University of Sao Carlos, Rodovia Washington Luís km 235 - SP-310, São Carlos, SP 13565-905, Brazil. Electronic address: ppregina@yahoo.com.br.
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Serrão
Department of Physiotherapy, Federal University of Sao Carlos, Rodovia Washington Luís km 235 - SP-310, São Carlos, SP 13565-905, Brazil. Electronic address: giclessi@gmail.com.
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Lessi
Institute of Physical Activity and Sport Sciences, Cruzeiro do Sul University, Rua Galvão Bueno, Liberdade, São Paulo, SP 01506-000, Brazil. Electronic address: jose.barela@cruzeirodosul.edu.br.
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Barela
Department of Human Movement Sciences, Federal University of São Paulo, Av. Ana Costa, 95, Vila Mathias, Santos, SP 11060-001, Brazil. Electronic address: raquelpcarvalho@gmail.com.
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Carvalho
Department of Physiotherapy, Federal University of Sao Carlos, Rodovia Washington Luís km 235 - SP-310, São Carlos, SP 13565-905, Brazil. Electronic address: stela.mattiello@gmail.com.
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Mattiello
D003430:Cross-Sectional Studies; D006801:Humans; D007537:Isometric Contraction; D007717:Knee / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009068:Movement; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000534:rehabilitation; D010146:Pain / Q000209:etiology; D004856:Postural Balance; D011187:Posture; D052097:Quadriceps Muscle / Q000503:physiopathology; D057566:Self Report; D019415:Torque
Knee osteoarthritis; Mini-squat; Muscle strength WOMAC; Postural stability