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Measurement of Spinal Stiffness in Predicting Treatment Response in Low Back Pain Patients

  • Author / Creator
    Hadizadeh Bajestani, Maliheh
  • Currently, manual posterior-anterior spinal stiffness assessment is widely used in daily practice to help determine how interventions for low back pain (LBP) are delivered. Given the poor reliability and validity of this assessment technique, mechanical indentation devices were developed. Early studies with these devices have shown an association between objective measures of stiffness and patient-reported outcomes. Unfortunately, these devices are typically designed to quantify stiffness only at one site which may ignore important data from other spinal segments. While it is possible to use these devices to obtain individual measurements from multiple sites, this approach requires time-consuming repositioning. To address this issue, a novel device called the VerteTrack (VT) was developed. Use of spinal stiffness derived from VT may improve the generally poor performance of predictive models which are used in attempts to optimize treatment outcomes for LBP. As instrumented measurements of spinal stiffness have not been incorporated into these prediction models to date, their use may improve specific patient outcomes such as LBP disability. This doctoral dissertation introduced and standardized a new spinal stiffness measurement device (VT) to provide data for predicting how patients respond to various interventions for LBP. Four studies informed the planning of this dissertation: 1) a reliability study to determine the within- and between-session reliability of lumbar stiffness measurements in asymptomatic participants using VT; 2) a Delphi study to develop a standard protocol for evaluating spinal stiffness and to improve the consistency of this assessment in future studies using the VT; 3) a secondary analysis of a large RCT to determine if prediction of short-term treatment response can be improved by including spinal stiffness measures (i.e. lumbar spine stiffness) and 4) another secondary analysis of the same RCT to determine if prediction of long-term treatment response can be improved by including spinal stiffness measures (i.e. lumbar spine stiffness). For Objective 1, the within and between-session reliability of lumbar spine stiffness measures using VT at the maximal tolerable load was excellent ranging from 0.95–1.00 and good to excellent ranging from 0.82–0.93, respectively. Using a standard Delphi methodology, Objective 2 developed a consensus-based protocol for measuring spinal stiffness. In total, the pre-defined consensus threshold was reached for 67.2% (123/ 183) of statements after three rounds of surveys. For Objective 3, a predictive model was developed for treatment response (30% improvement in Oswestry Disability Index) in a large RCT after 1 week. Response to treatment was predicted by a model containing height, gender, neck or upper back pain, pain frequency in the past 6 months, STarT Back Tool scores, patients’ expectations about medication and strengthening exercises, and extension status. The model performed superiorly compared to prior predictive models, but spinal stiffness was not included in the final model. A second predictive model was then created for Objective 4 using data from the same RCT. In this analysis, a novel approach was used that considered when responder status was first achieved during the trial (Response Onset (RO)), as well as if responder status was sustained (Response Persistence (RP)). Baseline variables that univariately differentiated category membership in RO and RP groupings included pain frequency, depression, neck/upper back pain history, pain intensity, weight, spinal stiffness with STarT Back scores being specific to RO and ultrasonic muscle thickness measurements being specific to RP. Regression analysis predicted category membership correctly 46.1% for RO and 39.4% correctly for RP. Maximum terminal stiffness, pain frequency, and neck/upper back pain history appeared in both regression models with lumbar flexion and predicted success with stabilization exercises appearing only in the RO model. To conclude, the VT is a reliable assessment device capable of measuring spinal stiffness continuously over an entire spinal region. A consensus-based protocol for measuring spinal stiffness using the VT is now available for operators to follow. Spinal stiffness measurements as collected by VT were not important in predicting treatment response in the short term but were a factor in identifying responders when multiple time point measurements were considered. In total, this dissertation suggests spinal stiffness measured by VT has predictive values when long-term and multiple time-points assessments are considered. Future studies would ideally evaluate responder status at different time points to develop a full understanding of the stiffness phenomenon.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/r3-wqpk-h016
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.