ABSTRACT
OBJECTIVE: This article presents a non-invasive protocol for the determination of lumbar spine mobility and compares intersegmental lumbar spinal mobility data from 45 subjects using both radiographic (invasive) and videographic (non-invasive) techniques. DESIGN: Non-linear mathematical models were developed to transfer skin marker coordinates into corresponding vertebral body positions. BACKGROUND: To relate skin surface motion with that of the underlying vertebrae and to enhance the reliability of using the non-invasive technique relied on a model of transformation. METHODS: This set of models was developed by taking the L(4) skinfold, the L(1)-S(1) skin distraction, and the non-linear difference between the lumbar spinal profile and the skin profile into consideration. Based on the digitized and model transformed data, the intersegmental joint angles (ISA) and intersegmental joint mobilities (ISM) were calculated and compared. RESULTS: In this study the non-invasive and invasive coordinate differences ranged from 0.485 to 1.099 cm; the mean ISA differences ranged from 0.29 to 2.08 degrees the mean ISM differences ranged from 0.62 to 1.88 degrees. CONCLUSIONS: With these small differences, the quality of the non-invasive protocol and the application of the transformation model were justified sufficient.
ABSTRACT
This article describes a sagittal motion model that transforms skin marker coordinates into corresponding vertebral body coordinates. Coordinate data were obtained from 45 subjects with radiopaque skin markers over the vertebral spinous processes. Data of 30 subjects were used for model development while data of the other Fifteen subjects were used for model validation. The subjects were subjected to lateral spinal radiographs in positions of neutral, flexion, and extension. The model was developed by taking the non-linear difference between lumbar spinal profile and skin profile, the L(4) skin-fold, and the difference of L(1)-S(1) skin distraction into consideration. Regression analysis shows high coefficients of determination (range, 62.43-99.86%; mean, 86.41%) in comparing the estimated position data with the actual data in all vertebral body positions. Based on the estimated coordinates, both the intersegmental joint angles and intersegmental joint mobilities were calculated. The result of this study using the non-invasive protocol and the transformation matrices demonstrated that the intersegmental sagittal motion of lumbar spine can be obtained with error ranged from 0.05 to 0.56 degrees.
