Do subjects with whiplash-associated disorders respond differently in the short-term to manual therapy and exercise than those with mechanical neck pain?

OBJECTIVE : To compare the short-term effects of manual therapy and exercise on pain, related disability, range of motion, and pressure pain thresholds between subjects with mechanical neck pain and whiplash-associated disorders. METHODS : Twenty-two subjects with mechanical neck pain and 28 with whiplash-associated disorders participated. Clinical and physical outcomes including neck pain intensity, neck-related disability, and pain area, as well as cervical range of motion and pressure pain thresholds over the upper trapezius and tibialis anterior muscles, were obtained at baseline and after the intervention by a blinded assessor. Each subject received six sessions of manual therapy and specific neck exercises. Mixed-model repeated measures analyses of covariance (ANCOVAs) were used for the analyses. RESULTS : Subjects with whiplash-associated disorders exhibited higher neck-related disability (P = 0.021), larger pain area (P = 0.003), and lower pressure pain thresholds in the tibialis anterior muscle (P = 0.009) than those with mechanical neck pain. The adjusted ANCOVA revealed no between-group differences for any outcome (all P > 0.15). A significant main effect of time was demonstrated for clinical outcomes and cervical range of motion with both groups experiencing similar improvements (all P < 0.01). No changes in pressure pain thresholds were observed in either group after treatment (P > 0.222). CONCLUSIONS : The current clinical trial found that subjects with mechanical neck pain and whiplash-associated disorders exhibited similar clinical and neurophysiological responses after a multimodal physical therapy intervention, suggesting that although greater signs of central sensitization are present in subjects with whiplash-associated disorders, this does not alter the response in the short term to manual therapy and exercises.