The relationship between measures of foot mobility and subtalar joint stiffness using vibration energy with color Doppler imaging-A clinical proof-of-concept validation study.

INTRODUCTION: Subtalar joint (STJ) dysfunction can contribute to movement disturbances. Vibration energy with color Doppler imaging (VECDI) may be useful for detecting STJ stiffness changes. OBJECTIVES: (1) Support proof-of-concept that VECDI could detect STJ stiffness differences; (2) Establish STJ stiffness range in asymptomatic volunteers; (3) Examine relationships between STJ stiffness and foot mobility; and (4) Assess VECDI precision and reliability for examining STJ stiffness. METHODS: After establishing cadaveric testing model proof-of-concept, STJ stiffness (threshold units, ΔTU), ankle complex passive range-of-motion (PROM) and midfoot-width-difference (MFWDiff) data were collected in 28 asymptomatic subjects in vivo. Three reliability measurements were collected per variable; Rater-1 collected on all subjects and rater-2 on the first ten subjects. Subjects were classified into three STJ stiffness groups. RESULTS: Cadaveric VECDI measurement intra-rater reliability was 0.80. A significantly lower STJ ΔTU (p = .002) and ankle complex PROM (p < .001) was observed during the screw fixation versus normal condition. A fair correlation (r = 0.660) was observed between cadaveric ΔTU and ankle complex PROM. In vivo VECDI measurements demonstrated good intra-rater (0.76-0.84) versus poor inter-rater (-3.11) reliability. Significant positive correlations were found between STJ stiffness and both dorsum (r = .440) and posterior (r = .390) PROM. MFWDiff exhibited poor relationships with stiffness (r = .103) and either dorsum (r = .256) or posterior (r = .301) PROM. STJ stiffness ranged from 2.33 to 7.50 ΔTUs, categorizing subjects' STJ stiffness as increased (n = 6), normal (n = 15), or decreased (n = 7). Significant ANOVA main effects for classification were found based on ΔTU (p< .001), dorsum PROM (p = .017), and posterior PROM (p = .036). Post-hoc tests revealed significant: (1) ΔTU differences between all stiffness groups (p < .001); (2) dorsum PROM differences between the increased versus normal (p = .044) and decreased (p = .017) stiffness groups; and (3) posterior PROM differences between the increased versus decreased stiffness groups (p = .044). A good relationship was found between STJ stiffness and dorsum PROM in the increased stiffness group (r = .853) versus poor, nonsignificant relationships in the normal (r = -.042) or decreased stiffness (r = -.014) groups. CONCLUSION: PROM may not clinically explain all aspects of joint mobility. Joint VECDI stiffness assessment should be considered as a complimentary measurement technique.

Increased spinal height using propped slouched sitting postures: Innovative ways to rehydrate intervertebral discs.

BACKGROUND: Upright and slouched sitting are frequently adopted postures associated with increased intradiscal pressure, spinal height loss and intervertebral disc pathology. OBJECTIVES: To examine the effects of two sustained propped slouched sitting (PSS) postures on spinal height after a period of trunk loading. METHODS: Thirty-four participants without a history of low back pain (LBP) were recruited (age 24.4 ± 1.6 years). Subjects sat in (1) PSS without lumbar support and (2) PSS with lumbar support for 10 min, after a period of trunk loading. Spinal height was measured using a stadiometer. RESULTS: Mean spinal height increase during PSS without lumbar support was 2.94 ± 3.63 mm and with lumbar support 4.74 ± 3.07 mm. CONCLUSIONS: Both PSS with and without lumbar support significantly increased spinal height after a period of trunk loading (p < 0.001). Such PSS postures can provide a valuable alternative to upright sitting and may be recommended for recovering spinal height in the working environment following periods of loading.

Dynamic balance as measured by the Y-Balance Test is reduced in individuals with low back pain: A cross-sectional comparative study.

OBJECTIVES: To determine the effects of current LBP (cLBP) and LBP history (hxLBP) on Y-Balance Test (YBT) reach and establish relationships between YBT performance and demographic, behavioral, and disability measures. DESIGN: Cross-sectional comparative study. SETTING: Research laboratory. PARTICIPANTS: Forty-two participants (24 males, 18 females) aged 18-50 years (30.9 ± 8.2 yr) in three groups: cLBP, hxLBP, and healthy controls. INTERVENTIONS: Three YBT trials in anterior (ANT), posterolateral (PL), and posteromedial (PM) directions. MAIN OUTCOME MEASURES: YBT reach (relative to leg length) was measured and compared amongst groups. Pearson correlations were calculated between reach distances and pain, disability, and fear avoidance scores in the cLBP and hxLBP groups and age and activity level in all participants. RESULTS: For PL reach, cLBP (94.7 ± 10.6 cm) and hxLBP (94.2 ± 9.2 cm) groups demonstrated shorter distances versus controls (105.8 ± 6.6 cm). For PM reach, cLBP (100.7 ± 8.4 cm) and hxLBP (102.3 ± 7.6 cm) groups' distances were shorter versus controls (109.3 ± 6.7 cm). No significant difference was found for ANT reach (control = 66.4 ± 7.0 cm; cLBP = 66.2 ± 6.2 cm; hxLBP = 66.4 ± 3.1 cm). No significant correlations were identified. CONCLUSION: YBT performance is reduced in individuals with cLBP and hxLBP in the PL and PM directions but not ANT. The YBT is useful for measuring balance deficits in these populations.

The Effect of Distractive Function on Volitional Preemptive Abdominal Contraction During a Loaded Forward Reach in Normal Subjects.

BACKGROUND: Volitional preemptive abdominal contraction (VPAC) is used to protect the spine and prevent injury. No published studies to data have examined the effect of distraction on VPAC use during function. OBJECTIVE: To examine the effect of an auditory distraction ("Stroop task") on healthy subjects' ability to sustain VPAC by use of the abdominal drawing-in maneuver during loaded forward reach. DESIGN: Within-subjects, repeated-measure cohort design. SETTING: Clinical laboratory setting. PARTICIPANTS: Convenience sample of 42 healthy individuals (ages 20-57 years). METHODS: Transversus abdominis (TrA) thickness was measured with M-mode ultrasound imaging. Each subject performed Stroop versus no Stroop during 4 conditions: (1) without VPAC, quiet standing; (2) with VPAC, quiet standing; (3) without VPAC, forward reach; and (4) with VPAC, forward reach. An investigator blinded to the conditions measured the first 10 subjects to establish intratester reliability of probe/transducer placement and TrA measurement. DATA REDUCTION: TrA thickness (mm) change represented VPAC performance. A single investigator measured onscreen TrA thickness twice at each second from second-6 through -10 on a recorded ultrasound imaging sequence. RESULTS: A 2 (Stroop) × 4 (Activity) repeated-measures analysis of variance found no significant Stroop × Activity interaction [F(3, 93) = 0.345, P = .793] and no main effect for Stroop [F (1,31) = 1.324, P = .259] but found a significant main effect for activity [F (3,93) = 17.729, P < .001]. Tukey post-hoc pairwise comparisons demonstrated significant differences between VPAC versus no-VPAC conditions, except between quiet standing/yes-VPAC and loaded forward reach/no-VPAC conditions (P = .051). The interclass correlation coefficient (3,2) for probe/transducer placement reliability was 0.87, 0.91, 0.92, and 0.93 for conditions 1-4, respectively. The interclass correlation coefficient (3,2) for TrA measurement reliability was 0.96, 0.99, 0.99, and 0.99 for conditions 1-4, respectively. CONCLUSION: A distracting executive function (Stroop task) did not produce a significant negative impact on normal individuals' ability to sustain a VPAC during quiet standing or loaded forward reach activities. LEVEL OF EVIDENCE: II.