Objective: The purpose of this study is to investigate the immediate effects of a single cervical spine manipulation and a manual contact intervention (MCI) on pressure pain thresholds (PPTs) and thermal pain thresholds over the elbow region and pain-free grip (PFG) force in patients with lateral epicondylalgia (LE).
Methods: A repeated measures, crossover, single-blinded randomized study was done. Ten patients with LE (5 female) aged from 30 to 49 years (mean, 42; SD, 6 years) participated in this study. Subjects attended 2 experimental sessions on 2 separate days at least 48 hours apart. At each session, participants received either a manipulative intervention or MCI assigned in a random fashion. Pressure pain threshold and hot and cold pain thresholds (HPT and CPT, respectively) over the lateral epicondyle of both elbows was assessed preintervention and 5 minutes postintervention by an examiner blinded to the treatment allocation of the patients. In addition, PFG on the affected arm and maximum grip force on the unaffected side were also assessed. A 3-way analysis of variance (ANOVA) with time (pre-post) and side (ipsilateral, contralateral to the intervention) as within-subjects variable and intervention (manipulation or MCI) as between-subjects variable was used to evaluate changes in PPT, HPT, CPT, or PFG.
Results: The ANOVA detected a significant effect for time (F = 37.2, P < .001) and a significant interaction between intervention and time (F = 25.1, P < .001) for PPT levels. Post hoc revealed that the manipulative intervention produced a greater increase of PPT in both sides when compared with MCI (P < .001). The ANOVA did not detect significant effects for time (F = 2.7, P > .2), intervention (F = 2.8, P > .2), or side (F = 0.9, P > .4) for HPT. Again, no significant effects for time (F = 0.8, P > .4), side (F = 0.6, P > .4), or intervention (F = 0.8, P > .5) was found for CPT. Finally, a significant interaction between intervention and time (F = 9.4, P = .004) and between time * side * intervention (F = 18.2, P < .001) was found for grip force. Post hoc analysis revealed that the cervical manipulation produced an increase of PFG on the affected side as compared with the MCI (P < .001).
Conclusions: The application of a manipulation at the cervical spine produced an immediate bilateral increase in PPT in patients with LE. No significant changes for HPT and CPT were found. Finally, cervical manipulation increased PFG on the affected side, but not the maximum grip force on the unaffected arm. Future studies with larger sample sizes are required to examine the effects of thrust manipulation on PPT, HPT, CPT, or PFG.