Study Design Single-blind, randomized trial. Objectives 1) To compare the effects of cervical and shoulder thrust manipulation (TM) and exercise on pain sensitivity, and 2) to explore associations with clinical outcomes in patients with shoulder pain. Background Experimental studies indicate spinal TM has an influence on central pain processes, supporting its application for treatment of extremity conditions. Direct comparison of spinal and peripheral TM on pain sensitivity has not been widely examined. Methods Seventy-eight participants with shoulder pain (36 female, mean age ± SD = 39.0 ± 14.5 years) were randomized to receive 3 treatments of cervical TM (n = 26) or shoulder TM (n = 27) or shoulder exercise (n = 25) over 2 weeks. Twenty-five healthy participants (13 female, mean age ± SD = 35.2 ± 11.1 years) were assessed to determine altered pain sensitivity in the clinical participants at baseline. Primary outcomes were changes in local (e.g., shoulder) and remote (e.g., tibialis anterior) pressure pain threshold (PPT) and heat pain threshold (HPT) occurring over 2 weeks. Secondary outcomes were shoulder pain intensity and patient-rated function at 4, 8, and 12 weeks. ANOVA models and partial correlation analyses were conducted for examining comparative effects and the relationship between measures. Results Clinical participants demonstrated lower local (mean difference (kg) = -1.63 [95% CI: -2.40; -0.86]) and remote PPT (mean difference (kg) = -1.96 [95% CI: -3.09; -0.82]) and HPT (mean difference (°C) = -1.15 [95% CI: -2.06; -0.24[) compared to controls suggesting enhanced pain sensitivity. Following intervention, there were no between-group differences in pain sensitivity or clinical outcome (p > 0.05). However, improvements were noted, regardless of intervention, for PPT (range of mean difference (kg) = 0.22 to 0.32 [95% CI: 0.03; 0.43]) and HPT (range of mean difference (°C) = 0.30 to 0.58 [95% CI: 0.06; 0.96]), and pain intensity (range of mean difference (x/10) = -1.79 to -1.45 [95% CI: 2.34; -0.94]) and function (range of mean difference (x/60) = 3.15 to 3.82 [95% CI: 0.69; 6.20]) at all time points. We did not find an association between pain sensitivity changes and clinical outcome (p > 0.05). Conclusion Clinical participants showed enhanced pain sensitivity, but did not respond differentially to cervical or peripheral TM. In fact in this sample, cervical TM, shoulder TM, and shoulder exercise had similar pain sensitivity and clinical effects. The lack of association between pain sensitivity and clinical pain and function outcomes suggests different (e.g. non-specific) pain pathways for clinical benefit following TM or exercise. Level of Evidence Therapy, Level 2b. J Orthop Sports Phys Ther, Epub 4 Mar 2015. doi:10.2519/jospt.2015.5745.

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