Assessment of in vivo 3D kinematics of cervical spine manipulation: Influence of practitioner experience and occurrence of cavitation noise.

BACKGROUND: Investigations on 3D kinematics during spinal manipulation are widely reported for assessing motion data, task reliability and clinical effects. However the link between cavitation occurrence and specific kinematics remains questionable. OBJECTIVES: This paper investigates the 3D head-trunk kinematics during high velocity low amplitude (HVLA) manipulation for different practitioners with respect to the occurrence of cavitation. METHODS: Head-trunk 3D motions were sampled during HVLA manipulation in twenty asymptomatic volunteers manipulated by four practitioners with different seniority (years of experience). Four target levels were selected, C3 and C5 on each side, and were randomly allocated to the different practitioners. The data was recorded before, during and after each set of trial in each anatomical plane. The number of trials with cavitation occurrence was collected for each practitioner. RESULTS: The manipulation task was performed using extension, ipsilateral side bending and contra-lateral axial rotation independent of side or target level. The displayed angular motion magnitudes did not exceed normal active ROM. Regardless cavitation occurrence, wide variations were observed between practitioners, especially in terms of velocity and acceleration. Cavitation occurrence was related to several kinematics features (i.e. frontal ROM and velocity, sagittal acceleration) and practitioner experience. In addition, multilevel cavitation was observed regularly. CONCLUSIONS: Kinematics of cervical manipulation is dependent on practitioner and years of experience. Cavitation occurrence could be related to particular kinematics features. These aspects should be further investigated in order to improve teaching and learning of cervical manipulation technique.

Effect of anatomical landmark perturbation on mean helical axis parameters of in vivo upper costovertebral joints.

The literature concerning quantification of costovertebral joint (CVJ) motion under in vivo conditions is scarce. Most papers concerning this topic are related to ex vivo loading conditions. In vivo protocols are available from the literature to determine rib and vertebra kinematics but new developments are needed to improve data processing concerning CVJ behaviour obtained from discrete breathing positions showing limiting ranges-of-motion and sensitive to noise. Data from previous work were used to implement a method analyzing mean helical axis (MHA) and pivot point parameters of the CVJ complexes. Several levels of noises were estimated within Monte-Carlo simulations to optimize MHA results. MHA parameters were then used to transform and define a CVJ-specific local coordinate system. This study proposes an improvement for CVJ kinematics processing and description from in vivo data obtained from computed tomography. This methodology emphasizes the possibility to work with variability of MHA parameters using Monte-Carlo procedures on anatomical landmark coordinates and to define a local coordinate system from this particular joint behaviour. Results from the CVJ joint model are closer to a hinge joint (secondary motions inferior to 3°) when anatomical frames are expressed from MHA orientation. MHA orientation and position data obtained from the proposed method are relevant according to angular dispersion obtained (from 7.5° to 13.9°) and therefore relevant to define behaviour of CVJ.