The role of an active muscular subsystem in prone instability test during rest and leg raise conditions.

BACKGROUND: Clinicians commonly used prone instability test (PIT) by assessing the posterior-to-anterior (PA) displacement to identify lumbar instability. Most studies focusing on passive subsystem found greater mobility in lower lumbar (L4-L5) than upper lumbar (L1-L3) spine. However, there is still a lack of evidence to demonstrate the role of active subsystem. Additionally, it is unclear whether sex affects PA displacements. AIM: To determine differences in displacement among five lumbar segments, between two testing positions (rest and leg raise), and between male and female during PIT in individuals with chronic non-specific low back pain (CNLBP). DESIGN: A cross-sectional study design. SETTING: Spine biomechanics laboratory. POPULATION: Individuals with CNLBP. METHODS: An electromagnetic tracking system was used to measure PA displacement with sensors attached at T12, S2 and a hand-held dynamometer. Participants were asked to perform PIT, while a 100N force was applied to each lumbar segment during resting and leg raise positions. RESULTS: Significantly less PA displacement (P<0.05) was seen in lower compared to upper lumbar spine and in leg raise compared to rest at L1 to L4. No significant interaction of sex with different lumbar levels and conditions (P>0.05) during PIT was found. CONCLUSIONS: Although previous studies have reported that the lower lumbar spine had greater mobility, the lower amount of displacement during the rest position suggests the role of an active subsystem contributing to lumbar stability regardless of sex. CLINICAL REHABILTATION IMPACT: A reduction in displacement during the leg raise position across L1 to L4 suggesting an interaction of stabilizing subsystems of the spine to provide lumbar stability.

The use of statistical parametric mapping to determine altered movement patterns in people with chronic low back pain.

Kinematics studies have generally focused on the quantity of movement using discrete parameters such as maximum and minimum angles to compare between people with chronic low back pain (CLBP) and healthy individuals. However, discrete parameters cannot be used to fully describe movement patterns and segmental contributions. This study aimed to explore the use of Statistical Parametric Mapping (SPM) to characterize quality of movement by examining if differences in movement patterns exist between groups, and within-group segmental contributions, during active movement tests. Twenty-one individuals with CLBP and nine healthy individuals were recruited. Inertial Measurement Unit (IMUs) were attached at thoracic (T3) and lumbar (L1) spine, and pelvis (S1) to collect active trunk flexion, extension, rotation, and lateral bend. SPM was used to analyze between-group movement patterns and within-group segmental contributions. SPM revealed no significant differences (P > 0.05) between groups. However, a greater lumbar contribution (P < 0.001) was observed during 10-40% of flexion followed by a greater pelvic contribution (P < 0.001) during 60-90% of flexion, while a greater lumbar than thoracic contribution (P < 0.001) was observed during flexion and the return to upright position in individuals with CLBP. Individuals with CLBP used a greater thoracic contribution compared to lumbar contribution (P < 0.001) during rotation, while a greater lumbar contribution compared to pelvic contribution was observed (P < 0.001) during lateral bending. Our findings suggest that SPM approach was able to detect differences in thoracic, lumbar, and pelvic velocity contributions and timings between segments in individuals with CLBP. These findings may help improving inter-rater reliability of clinical observations.

Multifidus Muscle Contractility Deficit Was Not Specific to the Painful Side in Patients with Chronic Low Back Pain During Remission: A Cross-Sectional Study.

Purpose: Morphology studies demonstrated that patients with chronic low back pain (CLBP) have bilateral multifidus muscle (LM) atrophy. This atrophy should result in LM contractility deficit bilaterally. Additionally, a recent study showed the effect of sex on LM thickness. Researchers proposed percentage LM contractility (LMCONT) as standardization to enable the comparison across participants. This study aimed to determine side-to-side difference in LMCONT and to determine the difference in LMCONT between males and females. Patients and Methods: Twenty-five healthy individuals (NoLBP group; 10 males and 15 females) and 35 with CLBP (CLBP group; 16 males and 19 females; 23 unilateral pain and 12 bilateral pain) were recruited. Ultrasound imaging was used to measure LM thickness at rest, during maximum voluntary isometric contraction, and during combined maximum voluntary isometric contraction with electrical stimulation. These data were used to calculate LMCONT. For unilateral CLBP, right and left LMCON were renamed to painful and non-painful sides. Results: Data demonstrated no significant difference (p > 0.05) between right (87.3 ± 13.7%) and left (87.2 ± 14.0%) in NoLBP, right (71.2 ± 15.7%) and left (76.5 ± 19.7%) in bilateral CLBP, and painful (70.3 ± 17.5%) and non-painful (77.7 ± 18.4%) in unilateral CLBP. No difference (p > 0.05) was found between males and females in both NoLBP (male 84.8 ± 6.5%, female 88.9 ± 15.4%) and CLBP groups (male 76.3 ± 15.5%, female 71.9 ± 14.0%). Conclusion: The findings suggested that LM contractility deficit in CLBP is not specific to painful side. No effect was found of sex on LM contractility. Therefore, we can use averaged LM activation across painful and non-painful sides and across males and females to compare between NoLBP and CLBP groups.