Abstract
STUDY OBJECTIVES: It has been demonstrated in recent studies that obstructive sleep apnea (OSA) is the most prevalent sleep disorder in patients with osteoarthritis (OA), and thus the current study aimed to investigate the influence of OSA on knee extensor torque, pain, stiffness, and physical function in men with low-grade knee OA. METHODS: The study included 60 male volunteers, aged 40 to 70 years, allocated into four groups: Group 1 (G1) Control (n = 15): without OA and without OSA; Group 2 (G2) (n = 15): with OA and without OSA; Group 3 (G3) (n = 15): without OA and with OSA; and Group 4 (G4) (n = 15) with OA and with OSA. All volunteers were examined using knee radiographs and polysomnography, responded to the Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaire, and completed a test on an isokinetic dynamometer to evaluate peak isometric knee extensor torque, both concentric and eccentric (90°/s and 180°/s). RESULTS: Regarding the data from the WOMAC questionnaire (for pain, stiffness, and physical function), it was observed that G4 showed higher values compared to G1 or G3. For the concentric isometric and isokinetic peak knee extensor torque, lower values were observed in G4 compared to G1 or G3. CONCLUSIONS: Patients who have knee OA in the early grades, when associated with OSA, have higher changes of the peak extensor torque, pain, stiffness, and physical function, compared with patients who did not have OSA. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov, Identifier: NCT01422967, Title: Changes Of Sleep on the Sensoriomotor and Cytokine In Patients With Osteoarthritis, URL: https://clinicaltrials.gov/ct2/show/NCT01422967.