Association between lumbopelvic motion and muscle activation in patients with non-specific low back pain during forward bending task: A cross-sectional study

Background: Evidence suggests patients with non-specific low back pain (NSLBP) have altered lumbar and pelvic movement patterns. These changes could be associated with altered patterns of muscle activation. Objective: The study aimed to determine: (1) differences in the relative contributions and velocity of lumbar and pelvic movements between people with and without NSLBP, (2) the differences in lumbopelvic muscle activation patterns between people with and without NSLBP, and (3) the association between lumbar and pelvic movements and lumbopelvic muscle activation patterns. Methods: Subjects (8 healthy individuals and 8 patients with NSLBP) performed 2 sets of 3 repetitions of active forward bending, while motion and muscle activity data were collected simultaneously. Data derived were lumbar and pelvic ranges of motion and velocity, and ipsilateral and contralateral lumbopelvic muscle activities (internal oblique[Formula: see text]transverse abdominis (IO[Formula: see text]TA), lumbar multifidus (LM), erector spinae (ES) and gluteus maximus (GM) muscles). Results: Lumbar and pelvic motions showed trends, but exceeded 95% confidence minimal detectable difference (MDD[Formula: see text]), for greater pelvic motion [Formula: see text], less lumbar motion [Formula: see text] among patients with NSLBP. Significantly less activity was observed in the GM muscles bilaterally [Formula: see text] in the NSLBP group. A significant association [Formula: see text], [Formula: see text] was found between ipsilateral ES muscle activity and lumbar motion, while moderate, but statistically non-significant associations, were found between GM muscle activity bilaterally and lumbar velocity [Formula: see text]ipsilateral: [Formula: see text], [Formula: see text]; contralateral: [Formula: see text], [Formula: see text] in the NSLBP group. Conclusion: Findings indicated patients had greater pelvic contribution, but less lumbar contribution which was associated with less activation of the GM bilaterally.

Biomechanical Comparison of Lumbar Motion Unit Stability Following Posterior Instrumentation with Facet Spacers and Facet Screws

Purpose Lumbar posterior instrumentation for facet stabilization has become popular for the treatment of lumbar instability. The present study investigated and compared facet stabilization following lumbar posterior instrumentation with facet spacers and facet screws using porcine lumbar spines. Methods Eighteen L5–L6 lumbar motion units (LMUs) of the porcine spines were randomly divided into three groups (un-instrumented, facet-spacer and facet-screw). In the un-instrumented group (control), all ligamentous structures were preserved. In the facet-spacer group, two facet spacers were inserted into the joint spaces of the bilateral upper and lower facets. In the facet-screw group, two cannulated screws were used to transfix the bilateral upper and lower facets. With the use of a material testing machine, a gradually increasing moment of up to 6000 N-mm was generated in flexion, extension, lateral bending and torsion motions to compare facet stabilization among the groups. Results The facet-spacer group was significantly stiffer than the facet-screw group in extension (p = 0.013), whereas the facet-screw group was significantly stiffer than the facet-spacer group in axial rotation (p = 0.004). No statistically significant differences were observed between the two fixation techniques in flexion (p = 0.284) and lateral bending (p = 0.085). Conclusion Both facet-spacer and facet-screw fixation techniques significantly improve stability in a single LMU. Facet-spacer fixation provided better stabilization in extension, while facet-screw fixation provided better stabilization in axial rotation.