The validation and use of a three dimensional goniometry system to investigate lumbar motion in healthy subjects and low back pain patients undergoing manual mobilisation.

Abstract

This study of lumbar spinal kinematics in healthy subjects and low back pain patients had three defined aims: The first aim was to investigate the lumbar spinal kinematics in healthy subjects during 6 gross movements and 4 functional activities using a newly developed electromagnetic measurement system and to establish a database for three dimensional kinematics with which subsequent patient data could be compared. The second aim was to investigate the effects of low back pain on lumbar spinal motion during 6 gross movements and 4 functional activities and hence contribute to the conceptual framework related to low back pain. The third aim involved a randomised controlled clinical trial to determine the immediate effects of low velocity mobilisations on pain, pattern and range of movement in acute/subacute low back pain patients and hence enhance the theory and practice of orthopaedic manipulative therapy. A series of validation tests were carried out on the measurement device (3 Space Isotrak) in order to determine its accuracy and precision. The device had a random error of 0.03 degrees and a systematic error of 0.45 degrees with a percentage linearity of 1.24%. Good linearity was shown up to ± 80 degrees whereafter the systematic error gradually increased. However, significant cross-talk between angulation recording channels limited the working range further to ±70 degrees. One-hundred healthy subjects in the age range 20 to 77 were recruited from a diverse population in Edinburgh. Excursion data for 5 age cohorts (males and females) were obtained over a 6 months period. These excursion data were obtained during a total of 10 tests (6 gross movements and 4 functional tasks). The normative data revealed that healthy subjects had a gradually decreasing - lumbar flexibility with age in both females and males with females showing greater lumbar flexibility then males. Regression analysis indicated that lumbar mobility was negatively associated with an increase in age and mass whereas height was not associated with lumbar flexibility and females showing greater flexibility than males. Statistical analysis was carried out, using independent t-tests, to test the hypothesis of no differences between healthy subjects and patients. A significant decreased mobility (p<0.05) in 5 out of the 6 gross, primary movements and 3 out of 4 functional, primary movements was found. Only small changes were observed in the associated, gross coupled movements. However, during the execution of the functional tasks significant differences (p<0.05) in the excursions of the coupled movements were recorded. Forty-one patients with uncomplicated low back pain were recruited into a randomised controlled trial. Using a blocked randomisation procedure, patients were assigned to an intervention group (n=20) and a delayed intervention group (n=21) where the former received the treatment immediately after the first measurement and the latter after 1/2 hours rest. Both groups received a low velocity mobilisation based on the Maitland concept. The mobility of the patients was measured 3 times within a time period of 2.5 hour. In addition, a visual analogue scale was used to record changes in pain or discomfort. An ANOVA-design was used to test the differences in excursion values-between and within the two groups and over the 3 tests occasions. Post-hoc analysis revealed no significant increase in mobility when the intervention group, after the treatment, was compared to the delayed intervention group before the treatment. Descriptive analysis of visual analogue scale scores revealed a reduced mean score·after intervention. However, non-parametric statistical analysis (Wilcoxon, signed rank test 2-tailed) revealed no significant reduction in pain levels experienced after a mobilisation intervention. The value of 3 dimensional motion recording in lumbar spine assessment is discussed. The clinical trial demonstrated that the newly developed system for 3 dimensional motion measurement can effectively measure small changes in lumbar spinal flexibility. It is easy to use in a physiotherapy out-patient clinic and can be successfully used to assess and evaluate three dimensional lumbar flexibility mobility in LBP-patients. The appropriateness of this newly developed system for clinical use in physiotherapy is debated. The lack of immediate effects after a lumbar mobilisation in the treatment of low back pain are discussed and potential implications for the conceptual framework regarding the use of low velocity mobilisations in the treatment of low back pain are provided.