Biomechanical performance of spinal manipulation therapy by newly trained vs. practicing providers: does experience transfer to unfamiliar procedures?

Objective: To examine the differences in predefined biomechanical parameters of spinal manipulation using a single method common to the training of both novice and expert manipulators.

Design: Analytic Cohort Study.

Participants: Fifteen novice manipulators and fifteen experienced physicians provided 2 applications of spinal manipulation therapy (SMT) to 15 healthy, male student volunteers. Assignment of volunteers was randomized, and the order of the first interaction with the manipulators was determined by coin toss and then inverted for the second.

Intervention: The bilateral transverse-thenar thoracic maneuver was selected from the diversified system of treatment to be used as the test procedure. Selection was guided by mechanical simplicity. SMT was applied at the physician's discretion to the region of T3-T10. Standard informed consent procedures were followed.

Main Outcome Measures: Preload force, rise rate of thrust and thrust force were selected as prospective primary outcome measures. Secondary descriptive measures included impulse, rise time, downward incisural point (DIP), fall time, total force, force components and direction cosines.

Results: Both novice and experienced manipulators were familiar with the transverse-thenar procedure, but only three of the experienced manipulators professed common use of it. Mean values for primary outcomes were all higher for the experienced participants; however, no statistically significant differences were found.

Discussion: Differences are presumed to exist between novice and experienced manipulators, as evidenced by measurement of arbitrarily selected thoracic and lumbar SMT. However, no systematic differences were found when the manipulators have a similar lack of practice experience specific to the test procedure. These results suggest the importance of regular use in developing skill of performance.