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.

THE TENSILE BEHAVIORS OF THE ILIOTIBIAL BAND - A CADAVERIC INVESTIGATION.

BACKGROUND: Clinical stretching is frequently recommended for iliotibial band syndrome management. Current literature lacks conclusive findings regarding isolated human iliotibial band tissue elongation and stiffness behaviors. Applying clinical-grade stretching force results to iliotibial band tissue behavior is thus challenging. PURPOSE: This study's objectives were to determine isolated iliotibial band tissue tensile behaviors during tension-to-failure testing and to relate the results to previously reported iliotibial band stretch findings. STUDY DESIGN: Descriptive in vitro laboratory study. METHODS: Ten isolated un-embalmed iliotibial band specimens were exposed to tension-to-failure testing using a 10kN material testing system. Peak load, load at yield point, and ultimate failure load were measured in Newtons. Corresponding absolute (mm) and relative (%) tissue deformation was recorded. Load-deformation curves were established to calculate iliotibial band stiffness (N/mm). RESULTS: A mean peak load of 872.8 ± 285.9N and resulting 9.0 ± 3.9% tissue deformation from initial length was recorded. An 805.5 ± 249.7N mean load at yield point and resulting 7.0 ± 1.9% tissue deformation was observed. A 727.6 ± 258.4N mean load was recorded directly prior to ultimate tissue failure. Mean tissue deformation at ultimate failure was 11.3 ± 4.2%. Mean iliotibial band system stiffness was 27.2 ± 4.5N/mm. CONCLUSION: The iliotibial band can withstand substantial tensile forces. Clinical stretching forces likely fall within the load-deformation curve elastic region and may not result in permanent iliotibial band tissue deformation. Sustained elongation resulting from stretching the ITB may require substantial patient compliance. Future studies should investigate potential underlying factors related to positive symptom relief from iliotibial band stretching that include immunological responses, fluid accumulation, altered proprioception, and pain perception. LEVEL OF EVIDENCE: 3.

THE CONSTRAINING EFFECT OF THE LATERAL FEMORAL INTERMUSCULAR SEPTUM ON PASSIVE HIP ADDUCTION IN UN-EMBALMED CADAVERS.

BACKGROUND: Due to the lack of verifiable iliotibial band elongation in response to stretching, the anatomical, biomechanical, and physiological responses to treatment of iliotibial band syndrome remain unclear. The lateral intermuscular septum, consisting of multiple myofibroblasts, firmly anchors the iliotibial band to the femur. PURPOSE AND HYPOTHESIS: The purpose of this in-situ study was to examine the constraining effect of the lateral intermuscular septum on available passive hip adduction range of motion in un-embalmed cadavers. It was hypothesized that an iliotibial band-septum-complex release would significantly increase passive hip adduction. DESIGN: Within-specimen repeated measures in-situ design. SETTING: Anatomy laboratory. METHODS: Metal markers were inserted into selected anatomical landmarks in eleven (11) un-embalmed human cadavers. With the specimen supine, the test-side lower limb was passively adducted until maximum passive hip adduction was reached. This movement was repeated three times each within two conditions: (1) band-septum-complex intact and (2) band-septum-complex dissected. Digital video of marker displacement was captured throughout each trial. Still images from a start and an end position were extracted from each video sequence. A custom Matlab program was used to calculate frontal plane hip adduction angle changes from obtained images. RESULTS: Mean change in passive hip adduction after band-septum-complex release was -0.3 ° (SD 1.6 °;95% CI: -1.33,0.76). A paired samples t-test revealed a non-significant difference (t=-.611; p=.555) in passive hip adduction for the band-septum-dissected condition (18.8 ± 3.9 °) versus the band-septum-intact condition (18.5 °±4.7 °). CONCLUSION: The lateral intermuscular septum does not appear to have a constraining effect on passive hip adduction in un-embalmed cadavers. Future research should evaluate the constraining effect of other selected tissues and conditions on hip adduction. Furthermore, inflammatory, metabolic, viscoelastic, and sensorimotor control properties within the iliotibial band in response to stretching should be investigated. LEVEL OF EVIDENCE: 3.

DEFORMATION RESPONSE OF THE ILIOTIBIAL BAND-TENSOR FASCIA LATA COMPLEX TO CLINICAL-GRADE LONGITUDINAL TENSION LOADING IN-VITRO.

BACKGROUND: Iliotibial Band (ITB) syndrome is a troublesome condition with prevalence as high as 12% in runners. Stretching has been utilized as a conservative treatment. However, there is limited evidence supporting ITB elongation in response to a stretching force. PURPOSE/HYPOTHESES: The purpose of this study was to describe the iliotibial band tensor fascia lata complex (ITBTFLC) tissue elongation response to a simulated clinical stretch in-vitro. The authors hypothesized that the ITBTFLC would undergo statistically significant elongation when exposed to a clinical-grade stretching regimen, with the majority of the elongation occurring within the proximal ITBTFLC region. STUDY DESIGN: Within subjects repeated measures in-vitro design. METHODS: The strain response of six un-embalmed ITBTFLCs to a simulated clinical stretch of 2.75% elongation was assessed. Four sets of array marks were placed along the length of the ITBTFLC. Photographic images were taken in resting position (with 1.0% in-situ elongation) and with an additional 2.75% elongation. Tissue elongation was compared between proximal, middle, and distal ITBTFLC regions. RESULTS: A paired samples t-test demonstrated a significantly longer ITBTFLC in the "stretched" versus resting condition (p = 0.001). Significant elongation was observed in the proximal (3.96mm (SD = 1.35); p = 0.001), middle (2.12mm (SD = 1.49); p = 0.018) and distal (2.25mm (SD = 1.37); p = 0.01) regions during the "stretched" versus the resting condition. A one-way ANOVA demonstrated a significant main effect for region (p = 0.002). The proximal region exhibited significantly greater elongation versus the middle (p = 0.003) and distal (p = 0.007) regions, with no significant difference between the middle and distal regions (p = 0.932). CONCLUSION: The results of this study demonstrate that the ITBTFLC is capable of elongation in response to a clinically simulated stretch. The proximal ITB region underwent significantly greater elongation than the middle and distal regions and may be more likely to respond to "stretching" in clinical situations. Future investigation should assess the ITBTFLC load/deformation properties to determine whether a short-term clinically available stretch translates into permanent tissue elongation. LEVEL OF EVIDENCE: III.