Thursday, September 27, 2018 8:30 AM–9:30 AM Best Papers: 105. In vivo biomechanics of cervical spine manipulation

Abstract

BACKGROUND CONTEXT Neck pain is one of the most commonly reported symptoms in primary care settings, and a major contributor to increasing health care costs. Cervical manipulation is a common and clinically effective intervention for neck pain. However, the in vivo biomechanics of manipulation are unknown due to the inability to accurately measure intervertebral kinematics in vivo during the manipulation. PURPOSE The objectives were to characterize manual forces and facet joint gapping during cervical spine manipulation and to assess changes in clinical and functional outcomes after manipulation. It was hypothesized that patient-reported pain would decrease and intervertebral range of motion would increase after manipulation. STUDY DESIGN/SETTING Laboratory-based prospective observational study. PATIENT SAMPLE A total of 15 patients with acute mechanical neck pain (5 M, 10 F; average age 40±14 years). OUTCOME MEASURES Amount and rate of cervical facet joint gapping during manipulation, amount and rate of force applied during manipulation, change in intervertebral range of motion from before to after manipulation, change in pain after manipulation. METHODS Initially, all participants completed a visual analog pain scale (0-10). Participants then performed full range of motion (ROM) flexion or extension, rotation, and lateral bending while seated within a custom biplane radiography system. Synchronized biplane radiographs were collected at 30 images/second for 3 seconds during each movement trial. Next, synchronized, 2.0 ms duration pulsed biplane radiographs were collected at 160 images/second for 0.8 seconds during the manipulation. The manipulation was performed by a licensed chiropractor using the thumb cervical extension technique. For the final five participants, two pressure sensors placed on the thumb of the chiropractor (Novel pliance system) recorded pressure at 160 Hz. After manipulation, all participants repeated the full ROM movement testing and once again completed the visual analog pain scale. A validated volumetric model-based tracking process that matched subject-specific bone models (from CT) to the biplane radiographs was used to track bone motion during manipulation with sub-millimeter accuracy. Facet joint gapping was calculated as the average distance between adjacent articular facet surfaces. Pre- to postmanipulation changes were assessed using paired t-tests. RESULTS The facet gap increased 0.98±0.30 mm during manipulation. The average rate of facet gapping was 7.4±2.9 mm/s. The peak force and rate of force application during manipulation were 65±4 N and 445±105 N/s. Pain score improved from 3.7 before manipulation to 2.0 after manipulation (p CONCLUSIONS This study is the first to measure facet gapping during cervical manipulation on live humans. These results improve our understanding of the basic in vivo biomechanics of spinal manipulation. Continuing this line of research will allow clinicians and researchers to design better interventions that reliably and sufficiently impact the key mechanisms behind manipulation. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.