Purpose To identify the best internal structure of the Tampa Scale for Kinesiophobia in chronic low back pain patients. Design Questionnaire validation study was designed for this study. Setting This study was conducted in physical therapy facility. Subjects Respondents reporting chronic low back pain (≥3 points on the 11-point Numerical Pain Rating Scale). Main measures We included participants of both sexes, with a self-report of low back pain ≥3 months and with pain intensity ≥3 on the 11-point Numerical Pain Rating Scale; participants also answered the Roland–Morris Disability Questionnaire and the Pain-Related Catastrophizing Thoughts Scale for low back pain disability and catastrophizing, respectively. The dimensionality and number of items of the Tampa Scale for Kinesiophobia were evaluated using the confirmatory factor analysis. Criterion validity was assessed using Spearman’s correlation coefficient using the original version of the 17-item Tampa Scale for Kinesiophobia as the gold standard. Results A total of 122 participants were included, with mean values of low back pain duration ≥48 months, pain intensity >5 and disability >8. Tampa Scale for Kinesiophobia structure with two domains and nine items was the most suitable, with adequate values in all fit indices (Chi-square/degree of freedom <3, Comparative Fit Index and Tucker–Lewis Index >0.90, and root mean square error of approximation <0.08) and lower Akaike information criterion and Bayesian information criterion values. We observed a high correlation between the 17-item Tampa Scale for Kinesiophobia and the activity avoidance domain (rho = 0.850, P < 0.001) and somatic focus domain (rho = 0.792, P < 0.001) of the nine-item Tampa Scale for Kinesiophobia. Conclusion Tampa Scale for Kinesiophobia structure with two domains (activity avoidance and somatic focus) and nine items is the most suitable for patients with chronic low back pain.

Osteoarthritis is a chronic degenerative disease that affects the joints, in particular, the knee is the most commonly affected. Pain, stiffness, and crepitus in joint movement are some of the symptoms that disable individuals. The treatment of this disease includes control of body mass (weight reduction), use of anti-inflammatory drugs, and exercise 1 .Recent studies have focused on understanding the risks of comorbidities associated with knee osteoarthritis 2 , the biochemical and gait parameters after arthroplasty 2,3 , and prognosis after therapies in bilateral knee osteoarthritis (B-KO) and unilateral knee osteoarthritis (U-KO) 4 .Asymmetry between the lower limbs seems to be more prevalent in individuals with B-KO 5 , while the reduction in muscle strength and volume of the affected limb is more observed in individuals with U-KO 6 , and both (B-KO and U-KO) have already been associated with primary and secondary hyperalgesia 7 . However, these clinical differences have been less investigated.Marmon et al. 8 and Messier et al. 9 described that, regardless of the number of affected knees, individuals with knee osteoarthritis have similar functional capacity and biomechanical parameters. Riddle and Stratford 10 pointed out that people with U-KO have higher levels of pain; however, according to the authors themselves, the differences between the clinical variables of bilateral and unilateral involvement in knee osteoarthritis remain controversial and little known. In this perspective, this study aimed to compare pain intensity, stiffness, functionality, central sensitization, and self-efficacy between individuals