Biomechanics Research Today is a free monthly online journal that collates and summarizes the latest research about Biomechanics, including details on mechanics of living organisms, movement, locomotion, prosthetic limbs.

Continuous dynamic spinal motion analysis.

Wong KW, Luk KD, Leong JC, Wong SF, Wong KK

Department of Physiotherapy, Queen Elizabeth Hospital, Kowloon, Hong Kong. kriswong@hkusua.hku.hk

STUDY DESIGN: Continuous dynamic lumbar intervertebral flexion-extension is assessed by a videofluoroscopy with a new auto-tracking system. OBJECTIVES: To develop and validate a new method for the continuous assessment of lumbar kinematics. SUMMARY OF BACKGROUND DATA: Instability of the lumbar spine is thought to be associated with low back pain, but the diagnosis remains difficult. Functional radiographs have been used for diagnosis of spinal instability but error and limitation exist, whereas videofluoroscopy provides a cost-effective way for such analysis. However, common approaches of image analysis of videofluoroscopic video are tedious and time-consuming because of the low quality of the images. Physicians have to extract the vertebrae manually in most cases; thus, continuous motion analysis is hardly achieved. METHODS: A new system that can perform automatic vertebrae segmentation and tracking is developed. In vitro and in vivo validity were evaluated. Intervertebral flexion and extension was assessed in 30 healthy volunteers. RESULTS: In vitro and in vivo validity tests have been conducted with good results. A linear-liked pattern of the intervertebral flexion-extension (IVFE) curves in different levels was found, and the IVFE decreased in descending order from L1-L5 at different points of range of motion in flexion. Conversely, extension is evenly contributed at different levels, and the concavity of lumbar lordosis increases steadily in backward movement. CONCLUSIONS: The newly developed technique in assessing the dynamic lumbar motion is reliable and able to analyze the lumbar intervertebral movement from videofluoroscopic images automatically and accurately. The proposed system requires less human intervention than common approaches. It may have a potential value in the evaluation of spinal "instability" in clinical practice.

Published 16 February 2006 in Spine, 31(4): 414-9.
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