Relation between changes in posteroanterior stiffness and active range of movement of the cervical spine following manual therapy treatment

Study Design. Repeated measures study of active and passive movements in patients with neck pain. Objectives. To determine if, following manual therapy: (1) changes occur in active range of movement (AROM) and stiffness of posteroanterior (PA) movements, (2) such changes are dependent on the location treated, and (3) there is a relation between changes in PA stiffness and AROM. Summary of Background Data. PA movements are frequently used to assess patients with neck pain but little is known about how these movements are related to patient symptoms. Methods. One location deemed symptomatic and hypomobile and 1 asymptomatic location were selected in 20 patients with neck pain for more than 2 weeks. PA stiffness at each location and AROM were measured before and after each of 4 manual therapy interventions: PA movements to each location, a general treatment, and a control intervention. Results. The general intervention had a greater increase in each axis of AROM than the other interventions (F = 2.814 to 7.929, DF = 3) but there were no differences in PA stiffness across interventions (F = 0.945, DF = 3). Differences in PA stiffness was divided into regions by applied force. After treatment to the symptomatic location, regions of stiffness at forces above 8 N demonstrated significant correlations with total AROM (R = -0.466 to -0.628). Conclusion. After manual therapy, increased AROM is related to decreased PA stiffness in patients with neck pain, but only for the treated location and only when that location had been identified previously as symptomatic and hypomobile.