A comparison of cervical spine mobilization forces applied by experienced and novice physiotherapists.

STUDY DESIGN: Clinical measurement, cross-sectional. OBJECTIVES: To compare cervical mobilization forces applied by physiotherapists and students, and the factors associated with forces for each group. BACKGROUND: Cervical spine joint mobilization is a common manual technique for treating patients with mechanical neck pain. But little is known about the forces applied during this technique. Potential variability between therapists may result from clinical experience or may be due to factors present in individuals prior to clinical practice exposure. METHODS: One hundred sixteen practicing physiotherapists and 120 physiotherapy students without clinical experience applied grades I through IV posteroanterior mobilization to the premarked C2 and C7 spinous and articular processes of 1 of 67 asymptomatic subjects. An instrumented table recorded applied forces (N), force amplitudes (N), and oscillation frequencies (Hz), and a custom device measured subjects' spinal stiffness (N/mm). Independent t tests were used to compare the forces applied by therapists and students, intraclass correlation coefficients were used to determine variability, and linear regression was used to establish factors associated with applied forces. RESULTS: Students' forces were generally lower (mean difference, 15.7 N for grades III and IV; P<.001) and applied with slower oscillation frequencies (0.12 Hz; P<.001) than therapists' forces. Similar factors were associated with applied forces for both groups: male gender and greater subject body weight were associated with higher applied forces, and greater C2 stiffness with lower forces. Having thumb pain was associated with lower applied forces for therapists but higher ones for students. CONCLUSIONS: Students apply lower forces than therapists. Similar factors appear to affect applied forces regardless of clinical experience.