Immediate effects of high-velocity thrust to the cervical spine on pressure pain threshold and pain-free grip strength in subjects with lateral epicondylalgia

Background and objective: To measure the immediate effect of a High-Velocity Low-Amplitude (HVLA) manipulation targeting the C5/6 vertebral segment on pain intensity in subjects with Lateral Epicondylalgia (LE). Design: Randomised assessor blinded controlled experiment. Methods: Ten subjects (7 male, 3 female; mean age= 37.7, SD=10.8) with unilateral elbow pain participated in this study. Prior to enrolment subjects were screened to establish the presence of LE. Pain-Free Grip Strength (PFGS) and Pressure Pain Threshold (PPT) at the lateral epicondyle were measured for both arms prior to and immediately following the application of either High-Velocity Low-Amplitude thrust targeting the C5/6 vertebral segment or the control condition. Results: The intervention group demonstrated an increase in mean Pain-Free Grip strength (37.9 ± 19.2N) following a High-Velocity Low-Amplitude manipulation (p=0.03, d=0.32) compared to a decrease in Pain-Free Grip Strength (25.6 ± 24.2N, p= 0.13) observed in the control group. The increase in Pain-Free Grip Strength observed in the intervention group exceeded the a priori Smallest Detectable Difference (14N). Neither the control or intervention group demonstrated substantial within group or between group change in mean Pressure Pain Threshold (control: p=0.59, 1.4 N/cm2; intervention: p=0.3, 3.3 N/cm2; between group: p=0.08, 8.8 N/cm2) following the intervention. Conclusion: High-Velocity Low-Amplitude thrust targeting the C5/6 vertebral segment can lead to a moderate increase in pain free grip strength in subjects with Lateral Epicondylitis. The change observed in PFGS following HVLA also indicates that further work exploring the proposed cervical component of LE is justified