Effect of hip and knee position on tensor fasciae latae elongation during stretching: An ultrasonic shear wave elastography study

Effective Stretching Positions of the Piriformis Muscle Evaluated Using Shear Wave Elastography

CONTEXT

Piriformis syndrome is often associated with muscle spasms and shortening of the piriformis muscle (PM). Physical therapy, including static stretching of the PM, is one of the treatments for this syndrome. However, the effective stretching position of the PM is unclear in vivo. This study aimed to determine the effective stretching positions of the PM using ultrasonic shear wave elastography.

DESIGN

Observational study.

METHODS

Twenty-one healthy young men (22.7 [2.4] y) participated in this study. The shear elastic modulus of the PM was measured at 12 stretching positions using shear wave elastography. Three of the 12 positions were tested with maximum internal rotation at 0°, 20°, or 40° hip adduction in 90° hip flexion. Nine of the 12 positions were tested with maximum external rotation at positions combined with 3 hip-flexion angles (70°, 90°, and 110°) and 3 hip-adduction angles (0°, 20°, and 40°).

RESULTS

The shear elastic modulus of the PM was significantly higher in the order of 40°, 20°, and 0° of adduction and higher in external rotation than in internal rotation. The shear elastic modulus of the PM was significantly greater in combined 110° hip flexion and 40° adduction with maximum external rotation than in all other positions.

CONCLUSION

This study revealed that the position in which the PM was most stretched was maximum external rotation with 110° hip flexion and 40° hip adduction.

Stretch tolerance and elastic passive reaction of the quadriceps femoris seem to depend more on the fascia profundis taut surfaces than on the underlying stretched muscle

The rectus femoris and its covering, the fascia lata (i.e., fascia profundis), are two anatomical structures involved in anterior thigh stretching. This study aimed to identify the role of strain changes in the fascia lata in limiting stretch tolerance. The reaction force intensity of 11 men and 5 women was assessed during passive stretching of the anterior thigh at 130, 110, 90, and 70° of knee flexion. Recent data suggest that the fascia lata strain field is modified with knee flexion. Therefore, the relationship between knee flexion angle and stretch tolerance was assessed. We found that the reaction force of the anterior thigh increased almost linearly with the degree of knee extension between 130° and 70°. The fascia lata stretched surface proprioceptive information seems responsible for stretch tolerance. Fascia profundis strain field must be considered during stretching experiments.

Effective stretching position for the posterior deltoid muscle evaluated by shear wave elastography

BACKGROUND

Deteriorated extensibility of the posterior deltoid muscle is one of the factors of posterior shoulder tightness, and improvement in its extensibility is needed. However, no study has investigated which shoulder positions effectively stretch the posterior deltoid muscle in vivo. The aim of this study was to verify the effective stretching position of the posterior deltoid muscle in vivo by shear wave elastography.

METHODS

Fifteen healthy men participated in this study. The shear modulus of the posterior deltoid was measured at resting and 13 stretching positions: 60°, 90°, and 120° shoulder flexion; maximum shoulder flexion, horizontal adductions at 60°, 90°, and 120° shoulder flexion; internal rotations at 60°, 90°, and 120° shoulder flexion; and combinations of horizontal adduction with internal rotation at 60°, 90°, and 120° shoulder flexion. The shear moduli of each stretching position were compared to those of the rest. Then, among the stretching positions for which the shear modulus was significantly different from the rest, the shear moduli were compared using a three-way analysis of variance with repeated measures of the 3 factors-flexion, horizontal adduction, and internal rotation.

RESULTS

The shear moduli in all stretching positions were significantly higher than those of the rest, except for maximum shoulder flexion. The three-way analysis of variance with repeated measures revealed significant main effects in flexion and horizontal adduction. Comparing the flexion angles, the shear modulus was significantly higher at 90° than that at 60° and 120°. The shear modulus with horizontal adduction was significantly higher than that without horizontal adduction. Moreover, a significant two-way interaction was found only at flexion and horizontal adduction. The shear modulus with horizontal adduction was significantly higher at all angles than that without horizontal adduction at each flexion angle. Comparing the flexion angles with horizontal adduction, the shear modulus was significantly higher at 90° than that at 60° and 120°. No significant three-way interactions were found.

CONCLUSION

Shoulder flexion and horizontal adduction affected the extensibility of the posterior deltoid muscle, whereas the effect of shoulder internal rotation was limited. More precisely, maximal horizontal adduction at 90° shoulder flexion was the most effective stretching position for the posterior deltoid muscle.

The effect of a shoe lift on tensor fasciae latae length during standing with an artificial functional leg length discrepancy: An ultrasonic shear wave elastography study

BACKGROUND

Shortening of tensor fasciae latae is one factor that causes a functional leg length discrepancy. A shoe lift has been used to correct the compensatory posture resulting from the discrepancy. Despite the potential therapeutic benefit of a shoe lift, the mechanism by which it exerts its effect is unclear.

OBJECTIVE

To investigate the effect of a shoe lift on tensor fasciae latae length during standing with an artificial functional leg length discrepancy using ultrasonic shear wave elastography.

METHODS

Twenty-two healthy individuals performed static standing under three conditions: drop of the pelvis and flexion of the leg resulting from fixing in the hip abduction position using a hip orthosis (functional leg length discrepancy condition); drop of the pelvis by the orthosis, but no flexion of the leg due to a shoe lift (shoe lift condition); and normal bilateral standing condition. The shear elastic modulus of tensor fasciae latae was calculated using ultrasonic shear wave elastography.

RESULTS

The shear elastic modulus was significantly lower in the functional leg length discrepancy condition than in the shoe lift and normal conditions (p= 0.038).

CONCLUSIONS

Using a shoe lift for the functional leg length discrepancy can result in a functional hip position that elongates tensor fasciae latae.

Effects of hot pack application before high-intensity stretching on the quadriceps muscle

Background/aims

High-intensity static stretching is assumed to increase the range of motion and/or decrease muscle stiffness; however, the effects of high-intensity static stretching on the quadriceps muscle have been debated. Hot pack application before high-intensity static stretching was assumed to decrease stretching pain, which is the main problem in high-intensity static stretching, and decrease quadriceps muscle stiffness. This study aimed to examine hot pack application before high-intensity static stretching on stretching pain, knee flexion range of motion, and quadriceps muscle stiffness.

Methods

In total, 21 healthy sedentary male participants randomly performed two interventions: high-intensity static stretching and hot pack application before stretching. Static stretching was performed at three 60-second stretching interventions with a 30-second interval. Then, a 20-minute hot pack was applied before high-intensity static stretching. The knee flexion range of motion and shear elastic modulus of the quadriceps muscle were measured by ultrasonic shear-wave elastography before and after the static stretching intervention.

Results

Stretching pain after hot pack application before stretching was lower than high-intensity static stretching alone. Significant increases were also found in knee flexion range of motion after both stretching interventions, but no significant difference was noted in the increase in the knee flexion range of motion with or without hot pack application. No significant change was found in quadriceps muscle stiffness in either intervention.

Conclusions

The results suggest that hot pack application before high-intensity static stretching could decrease stretching pain, but no significant difference in knee flexion range of motion increase was found.

Effective muscle elongation positions for the neck extensor muscles: An ultrasonic shear wave elastography study

This study aimed to clarify the effective stretching positions for neck extensor muscles. Fifteen healthy men were measured shear moduli of the right neck extensor muscles using ultrasound shear wave elastography in following positions: rest (Rest), flexion (Flex), contralateral bending (Bend), flexion + contralateral bending (Flex → Bend), flexion + contralateral bending + contralateral rotation (Flex → Bend → ConRot), and flexion + contralateral bending + ipsilateral rotation (Flex → Bend → IpsRot). The increase in the shear modulus indicated a greater muscle elongation. Regarding the upper trapezius and splenius capitis, the shear moduli at Flex → Bend, Flex → Bend → ConRot, and Flex → Bend → IpsRot were significantly higher than those at Rest. The shear moduli at stretching positions, including contralateral bending, were significantly higher than those at Rest and Flex in the levator scapulae. The results indicated that the stretching position with a combination of flexion and contralateral bending could be effective for elongation of the upper trapezius and splenius capitis. Furthermore, the stretching positions including contralateral bending could be effective for the levator scapulae.

Effective stretching positions for the posterior shoulder capsule as determined by shear wave elastography

BACKGROUND

Stretching is often used to prevent and treat posterior shoulder capsule tightness; however, the most effective stretching positions are not clearly defined. The purpose of this study was to identify the stretching positions that specifically applied the greatest passive tension on the posterior shoulder capsule by evaluating the elastic characteristics of posterior capsules and muscles in various stretching positions using ultrasound shear wave elastography (SWE).

METHODS

We evaluated 9 fresh-frozen shoulders (mean age 86.6 ± 7.7 years) without osteoarthritis or rotator cuff tears. All posterior shoulder tissues were preserved intact. Shear moduli of the middle and inferior posterior shoulder capsules and the posterior shoulder muscles were evaluated using SWE. We obtained shear modulus measurements in 9 stretching positions using a combination of glenohumeral elevation planes and angles (frontal, sagittal, scapular; -30°, 0°, 30°, 60°, respectively). A 4-Nm torque for shoulder internal rotation or horizontal adduction was applied in each position. We also measured shear moduli in the resting position (0° elevation with neutral shoulder internal/external rotation). We compared the shear moduli of all stretching and resting positions using 1-way repeated measures analysis of variance (P < .05). In addition, we compared the shear modulus in 2 positions (ie, resting and each stretching) among tissues (ie, capsules and muscles) with repeated measures using 2-way analysis of variance (P < .05).

RESULTS

Shear modulus values for the middle posterior capsules in "internal rotation at 30° in scapular plane elevation" (28.7 ± 14.3 kPa, P = .01) and in "horizontal adduction at 60° of elevation" (31.1 ± 13.1 kPa, P < .001) were significantly higher than that of the resting position (11.0 ± 7.3 kPa). The shear modulus value for the inferior posterior capsule in "internal rotation at 30° of flexion" was significantly higher than that of the resting position (39.0 ± 17.3 vs. 15.4 ± 13.9 kPa, respectively; P = .004). Additionally, the shear modulus values for the posterior capsules in "internal rotation at 30° in scapular plane elevation and flexion" were significantly higher than that of the posterior shoulder muscles.

CONCLUSION

Effective middle posterior shoulder capsule stretching positions were shoulder "internal rotation at 30° of scapular plane elevation" and "horizontal adduction at 60° of elevation." Shoulder "internal rotation at 30° of flexion" was the most effective position for the inferior posterior shoulder capsule. Stretching in these positions could relieve posterior shoulder capsule tightness and contribute to the prevention and treatment of throwing injuries of the shoulder.

Regional differential stretching of the pectoralis major muscle: An ultrasound elastography study

Pectoralis major (PMa) muscle injuries are becoming more prevalent, and their incidence differs among the PMa regions, i.e., the clavicular, sternal, and abdominal regions. Therefore, identifying the position for effectively lengthening each PMa region is critical in preventing PMa injuries. The purpose of this study was to determine the effective stretching position for each PMa region through shear wave elastography, which can indirectly assess individual muscle lengthening. Fifteen men participated in this study. Twelve stretching positions were compounded with shoulder abductions (45°, 90°, and 135°), pelvic rotation (with or without), shoulder external rotation (with or without), and shoulder horizontal abductions. The shear modulus of each PMa region was measured through shear wave elastography in the stretching positions mentioned above. At the clavicular region, the shear modulus was higher for three stretching positions: shoulder horizontal abduction at 45° abduction during pelvic rotation and shoulder external rotation, shoulder horizontal abduction at 90° abduction, and shoulder horizontal abduction at 90° abduction while considering shoulder external rotation. For the sternal region, the shear modulus was higher in two stretching positions: shoulder horizontal abduction at 90° abduction while adding external rotation, and combination of pelvic rotation and external rotation. For the abdominal region, the shear modulus was higher in the shoulder horizontal abduction at 135° abduction with pelvic and external rotation. These results indicated that the effective stretching position was different for each PMa region.

Effective stretching position of the coracobrachialis muscle

An increase in the stiffness of the coracobrachialis muscle can restrain proper movement of the glenohumeral joint and scapula during arm elevation. Therefore, muscle stiffness should be reduced through stretching. The aim of this study was to determine the effective stretching position of the coracobrachialis muscle using ultrasound shear wave elastography imaging to evaluate the stiffness of individual muscles. Eighteen healthy young men participated in this study. The shear modulus of the coracobrachialis muscle was measured at the following eight shoulder positions: i) 20° abduction (Rest), ii) maximal external rotation at 90° abduction (ER2), iii) maximal internal rotation at 90° abduction (IR2), iv) maximal flexion (Flex), v) maximal extension (Ext), vi) maximal horizontal abduction at 90° abduction (Hab), vii) maximal horizontal abduction and maximal external rotation at 90° abduction (HabER), and viii) maximal horizontal abduction and maximal internal rotation at 90° abduction (HabIR). The shear modulus in each position was compared with that of Rest using the Wilcoxon signed-rank test, and a multiple comparison test was performed among the positions that exhibited significant difference. The shear modulus of all stretching positions was significantly higher than that of Rest, except for Flex. Moreover, the shear moduli of IR2, Ext, Hab, HabER, and HabIR were significantly higher than that of ER2. The shear modulus of Ext was significantly higher than that of HabIR. The coracobrachialis muscle could be stretched effectively at IR2, Ext, Hab, HabER, and HabIR. Among these positions, Ext, Hab, and HabER are recommended for clinical settings.

Differences in shear elastic modulus of the latissimus dorsi muscle during stretching among varied trunk positions

The latissimus dorsi (LD) can be divided into the upper, middle, and lower parts, but the effective stretching positions for each part are unknown. In this study, we aimed to investigate effective trunk positions for stretching of the LD. A total of 14 healthy males participated in this study. The following seven trunk positions were chosen as the LD stretching positions; upright of the trunk (Baseline), flexion of the trunk (Flex), contralateral bending of the trunk (LB), contralateral rotation of the trunk (Rot), flexion and contralateral bending of the trunk (Flex + LB), flexion and contralateral rotation of the trunk (Flex + Rot), and contralateral bending and contralateral rotation of the trunk (LB + Rot). Maximal elevation of the upper limb was passively added to all positions. The shear elastic modulus, used as the index of muscle elongation, was measured at the four parts (upper, middle, lower, distal parts) of the LD. The shear elastic moduli showed obviously high values in Rot and LB + Rot at the upper, middle, and distal parts, and also in LB, Rot, and LB + Rot at the lower part. These findings suggest that contralateral trunk rotation, or a combination of contralateral trunk bending and rotation are effective trunk positions for stretching all parts of the LD. Contralateral trunk bending was also effective for stretching the lower part of the LD.

The function of the popliteus muscle: An in vivo ultrasound shear wave elastography study

The function of the popliteus muscle [PM] is crucial to knee function. However, it remained unclear in vivo. Thus, this study aimed to explore the PM function in the non-weight-bearing and the weight-bearing conditions in vivo. Fourteen healthy subjects participated in this study. The muscle stiffness of the PM was measured using shear wave elastography as an index of muscle force. Muscle stiffness was measured at 30° knee flexion as a reference value. Muscle stiffness was also measured at passive 0°knee flexion and passive 20° external rotation and internal rotation at 30° knee flexion, and during isometric knee extension, flexion, external rotation, and internal rotation at 30° knee flexion. Moreover, muscle stiffness was measured during one-leg standing at 0° and 30° of knee flexion. Muscle stiffness was significantly greater at passive 0° knee flexion and 20° external rotation and during isometric knee flexion and internal rotation than the reference value. Two-way analysis of variance revealed significant main effects of weight bearing and knee angle: Muscle stiffness increased with weight bearing and knee extension. Moreover, muscle stiffness was significantly lower at 30° than at 0° knee flexion during one-leg standing. The PM function is knee flexion and internal rotation, and the PM force increases with weight bearing and decreases with knee flexion during one-leg standing.

Soft Tissue Mobilization and Stretching for Shoulder in CrossFitters: A Randomized Pilot Study

Background. The shoulder in CrossFit should have a balance between mobility and stability. Glenohumeral internal rotation deficit and posterior shoulder stiffness are risk factors for overhead shoulder injury. Objective. To determine the effectiveness of instrument-assisted soft tissue mobilization and horizontal adduction stretch in CrossFit practitioners’ shoulders. Methods: Twenty-one regular CrossFitters were allocated to experimental (stretching with isometric contraction and instrument-assisted soft tissue mobilization) or control groups (instrument-assisted soft tissue mobilization). Each session lasted 5 min, 2 days a week, over a period of 4 weeks. Shoulder internal rotation and horizontal adduction (digital inclinometer), as well as posterior shoulder stretch perception (Park scale), were evaluated. Shapiro–Wilk test was used to analyze the distribution of the sample. Parametric Student’s t-test was used to obtain the intragroup differences. The inter- and intra-rater differences were calculated using a repeated measures analysis of variance (ANOVA). Results. Average age was 30.81 years (SD: 5.35), with an average height of 178 (SD: 7.93) cm and average weight of 82.69 (SD: 10.82) kg. Changes were found in the experimental group following intervention (p < 0.05), and when comparing baseline and follow-up assessments (p < 0.05) in all variables. Significant differences were found in the control group following intervention (p < 0.05), in right horizontal adduction and left internal rotation. When comparing the perception of internal rotation and horizontal adduction in both groups, significant differences were found. Conclusions. Instrument-assisted soft tissue mobilization can improve shoulder horizontal adduction and internal rotation. An instrument-assisted soft tissue mobilization technique yields the same results alone as those achieved in combination with post-isometric stretch with shoulder adduction.

Modeling the effect of static stretching and strengthening exercise in lengthened position on balance in low back pain subject with shortened hamstring: a randomized controlled clinical trial

BACKGROUND

Hamstring shortening may have negative impacts on function and biomechanics of knee and hip joints and lumbo-pelvic rhythm. Many interventions are believed to correct hamstring to its normal length. There are several reports of impairment in postural control of patients with low back pain. The purpose of this study was to compare the effect of stretching exercise and strengthening exercise in lengthened position of the hamstring muscle on improving the dynamic balance of the person in patients with chronic low back pain with short hamstring muscles.

METHODS

Forty-five patients with hamstring shortening who referred to physiotherapy clinic of Kermanshah university of Medical Sciences, Kermanshah, Iran were randomly allocated to the three groups; static stretching (n = 15), strengthening exercise in lengthened hamstring position (n = 15) and control (n = 15). All groups received conventional physiotherapy for low back pain and the two intervention groups received stretching exercise and strengthening exercise in lengthened position programs as well. All groups performed three treatment sessions for a week, a total of 12 sessions. For balance assessment, Y-Balance test was performed for each participant in three reach directions. To determine the important and significant variables, all variables entered a model (Generalized Estimation Equations method).

RESULTS

The results indicate that based on GEE model, by controlling other variables, participants of static stretching exercise showed more improvement in balance than control group (β = 9.58, p-value = 0.014). Also, balance status showed significant improvement in the end of study compared to baseline of the study (β = 7.71, P-value< 0.001). In addition, the balance in three reach directions improved significantly and the greatest balance improvement was in the anterior reach direction (β ranged over = 6.16 to 11.59) and the height of patients affected their balance (β = 0.28, P-value = 0.034).

CONCLUSIONS

Group (type of intervention), phase of intervention, reach direction of test (anterior, posteromedial and posterolateral) and height of participants were associated with balance performance. Static stretching exercise was more effective than muscle strengthening exercise in lengthened position for improving dynamic balance in low back pain patients with hamstring tightness.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (I RCT201507258035n2 ). Registered 16th September 2015.

Site dependent elastic property of human iliotibial band and the effect of hip and knee joint angle configuration

The iliotibial band (ITB) is the lateral thickening of the fascia lata. The ITB has been extensively studied for its relevance to injury, but not much is known about its elastic properties. We aimed to investigate the site- and joint angle-dependence of ITB elasticity. We tested twelve healthy males (22-30 years; in vivo) and twelve male cadavers (69-93 years; cadaver). The Young's modulus of the ITB was measured in the longitudinal direction at five sites (over the proximal, middle, and distal bellies of the vastus lateralis (VL), superior border of the patella, and between femur and tibia) of the right limb, by ultrasound shear wave elastography (in vivo) and the tensile test (cadaver). Joint angle-dependence was also studied for nine different positions (knee angles at 0, 25, 90˚ x hip angles at 0, 40, 90˚) (in vivo). Over VL, the ITB was more compliant at the distal (17.6-190.1 kPa; in vivo, 219.4 ± 68.8 MPa; cadaver, mean ± SD) than other sites (24.2-221.4 kPa, 337.9-362.7 MPa). The ITB at the superior border of the patella and between femur and tibia was stiffer in vivo (31.8-271.8 and 50.9-208.8 kPa), while it was more compliant in cadavers (113.4 ± 63.7 and 130.4 ± 73.7 MPa), compared to other sites. The ITB became stiffer associated with increasing hip extension angle and knee flexion angle, and the hip remarkably affecting the values regardless of site (in vivo). Our findings have clinical significance with respect to the site- and joint angle-dependence of ITB-related overuse injury.

Sensory regulation and mechanical effects of sustained high intensity stretching of the anterior compartment of the thigh

BACKGROUND

Ballet dancers, contortionists, gymnasts, or other sportspeople spend long hours performing stretches while training. Although most studies on stretching consider fascia lengthening to be difficult, athletes manage to lengthen their fascia.

AIM

To assess the relationship between lengthening fascial structures of the anterior compartment of the thigh and the self-reported sensation of discomfort and pain during a sustained and repeated high intensity stretch.

METHODS

Our analysis was based on the data of 7 high school male elite rugby players who completed 11 sessions of stretching (10-min quasi-static stretch of the rectus femoris and fascia lata, at the maximum intensity tolerated), performed twice per week. The measured outcomes included hip range of motion, the length of the structures of the anterior compartment, subjective pain and tension during the stretch, and the level of surface electromyography activity. Values were compared before and after completion of the 11 sessions.

RESULTS

Myofascial length increased by 1 cm. The necessary force applied increased from 124 to 164 N. However, the maximal tolerated stretching intensity did not change significantly (from 205 to 206 N). The increase in length was principally contributed by the rate of fascial creep upon force application, and not by contractile tissue. Subjective levels of tension were related to the stretching force applied and pain was related to the lengthening.

CONCLUSION

Sensations can be used to adjust the intensity and duration of stretching. Soft matter physics provides a new interpretation of fascia lengthening and strengthening during a high intensity stretch.

Muscle activity of the vastus medialis obliquus during squat motion after static stretching of the tensor fasciae latae

[Purpose] The purpose of this study was to investigate the changes of muscle activity during squat motion after stretching the tensor fasciae latae muscle. [Participants and Methods] The participants comprised 19 healthy males. The test muscles were the vastus medialis obliquus and vastus lateralis. The participants performed the squat motion before and after stretching the tensor fasciae latae. We measured the muscle activities and the onset timing of the vastus medialis obliquus relative to that of the vastus lateralis during squat motions. [Results] The onset timing of the vastus medialis obliquus relative to that of the vastus lateralis was decreased, and the vastus medialis obliquus activity and vastus medialis obliquus/vastus lateralis activity ratio were increased after stretching the tensor fasciae latae. [Conclusion] This study revealed that stretching of the tensor fasciae latae increases the relative vastus medialis obliquus muscle activity.

Using shear-wave elastography in skeletal muscle: A repeatability and reproducibility study on biceps femoris muscle

Shear-wave electrography (SWE) is a method used to assess tissue elasticity. Recently, it has been used to assess muscle stiffness, but the reliability of SWE for this purpose has not been thoroughly investigated. The purpose of this study was to evaluate the repeatability and reproducibility of SWE on porcine meat specimens and the human biceps femoris muscle. Measurements on meat specimens (n = 20) were performed by three raters and with a custom-built device that allowed constant application force. Measurements on human participants (n = 20) were performed by two raters in relaxed and stretched muscle positions on two visits. Most aspects of repeatability and reproducibility were good or high, with intra-class correlation coefficient (ICC) values above 0.70. Minimal detectable changes were lower in a relaxed (6–10%) than stretched (15-16%) muscle position. In conclusion, SWE is a reliable tool for assessing muscle stiffness if the muscle is examined in relaxed condition, while changing the force applied with the probe for as little as 1.5 N results in significantly lower repeatability.

Comparative Study of the Effects of Customized 3D printed insole and Prefabricated Insole on Plantar Pressure and Comfort in Patients with Symptomatic Flatfoot

BACKGROUND There are many shortcomings in traditional prefabricated rehabilitation insoles for symptomatic flatfoot patients. This study investigated the effects of customized 3-dimensional (3D) printed insoles on pressure and comfort of the plantar foot in symptomatic flatfoot patients. MATERIAL AND METHODS Eighty patients with bilateral flatfoot participated in this study. At week 0, patients were randomly assigned into 1 of 2 groups. In the control group, the patients wore standardize shoes with prefabricated insoles; and in the experimental group the patients wore standardize shoes and customized insoles. The Footscan® system recorded peak pressure, peak force, and peak contact area in 10 areas of the sole at weeks 0 and at week 8. Patients used visual analogue scale scores at week 0 and at week 8 to assess overall comfort of insoles. RESULTS At week 0, compared with the control group, the peak pressure in the metatarsal was significantly lower in the experimental group (P<0.05) while the peak pressure in the mid-foot was significantly higher than the control group (P<0.05). At week 8, in the experimental group, the peak pressures in the mid-foot were significantly higher than the control group (P<0.05). The comfort scores (measured by pain scale) reported by the experimental group were significantly lower than those reported by the control group (P<0.05). CONCLUSIONS Customized 3D printed insoles reduced the pressure on the metatarsals by distributed it over the mid-foot area, thus reduced the damage from symptomatic flatfoot. Customized 3D printed insoles were more effective than prefabricated insoles and offered better comfort for patients with symptomatic flatfoot.

Posture-related stiffness mapping of paraspinal muscles

The paraspinal compartment acts as a bone-muscle composite beam of the spine. The elastic properties of the paraspinal muscles play a critical role in spine stabilization. These properties depend on the subjects' posture, and they may be drastically altered by low back pain. Supersonic shear wave elastography can be used to provide quantitative stiffness maps (elastograms), which characterize the elastic properties of the probed tissue. The aim of this study was to challenge shear wave elastography sensitivity to postural stiffness changes in healthy paraspinal muscles. The stiffness of the main paraspinal muscles (longissimus, iliocostalis, multifidus) was measured by shear wave elastography at the lumbosacral level (L3 and S1) for six static postures performed by volunteers. Passive postures (rest, passive flexion, passive extension) were performed in a first shear wave elastography session, and active postures (upright, bending forward, bending backward) with rest posture for reference were performed in a second session. Measurements were repeated three times for each posture. Sixteen healthy young adults were enrolled in the study. Non-parametric paired tests, multiple analyses of covariance, and intra-class correlations were implemented for analysis. Shear wave elastography showed good to excellent reliability, except in the multifidus at S1, during bending forward, and in the multifidus at L3, during bending backward. Yet, during bending forward, only poor quality was recorded for nine volunteers in the longissimus. Significant intra- and inter-muscular changes were observed with posture. Stiffness significantly increased for the upright position and bending forward with respect to the reference values recorded in passive postures. In conclusion, shear wave elastography allows reliable assessment of the stiffness of the paraspinal muscles except in the multifidus at S1 and longissimus, during bending forward, and in the multifidus at L3, during bending backward. It reveals a different biomechanical behaviour for the multifidus, the longissimus, and the iliocostalis.

Effect of 3D Printing Individualized Ankle-Foot Orthosis on Plantar Biomechanics and Pain in Patients with Plantar Fasciitis: A Randomized Controlled Trial

BACKGROUND Traditional ankle-foot orthoses (AFOs) are not effective in treating plantar fasciitis, while customized 3-dimensional (3D) printed ankle-foot orthoses are effective in treating many ankle-foot diseases. This study investigated the effects of customized 3D printed AFOs on biomechanics and comfort of the plantar foot in plantar fasciitis. MATERIAL AND METHODS Sixty patients with bilateral plantar fasciitis aged 31-60 years participated in this study. At week 0, patients were randomly assigned into 2 groups: the control group consisting of those wearing separate shoes with prefabricated AFOs; and the experimental group consisting of those wearing a separate shoe and customized 3D-printed AFO. The Footscan® system recorded maximum pressure, maximum strength, and contact area of patients' hallux, toes 2-5, first to fifth metatarsal, midfoot, lateral heel, and midfoot heel at weeks 0 and 8. Patients used visual analogue scale scores at weeks 0 and 8 to assess overall comfort of foot orthosis, to determine the credibility and comfort of both orthopedic insole conditions. RESULTS At week 0, in the experimental group, peak pressure in the hallux and first metatarsal area was significantly higher than the control group (P<0.05), while mid-heel and lateral heel peak pressures were significantly lower than the control group (P<0.05). After 8 weeks, all groups reported more comfort compared with the same group in week 0 (P<0.05). The comfort scores reported by the experimental group were significantly lower than those of the control group (P<0.05). CONCLUSIONS This study supports the efficiency of customized 3D printing AFO for reducing damage associated with plantar lesions and improving comfort in patients with plantar fasciitis compared with prefabricated AFO. Customized AFO is useful in the treatment of plantar fasciitis compared with prefabricated AFOs.

Shear wave sonoelastography of skeletal muscle: basic principles, biomechanical concepts, clinical applications, and future perspectives

Imaging plays an important role in the diagnosis and therapeutic response evaluation of muscular diseases. However, one important limitation is its incapacity to assess the in vivo biomechanical properties of the muscles. The emerging shear wave sonoelastography technique offers a quantifiable spatial representation of the viscoelastic characteristics of skeletal muscle. Elastography is a non-invasive tool used to analyze the physiologic and biomechanical properties of muscles in healthy and pathologic conditions. However, radiologists need to familiarize themselves with the muscular biomechanical concepts and technical challenges of shear wave elastography. This review introduces the basic principles of muscle shear wave elastography, analyzes the factors that can influence measurements and provides an overview of its potential clinical applications in the field of muscular diseases.

Acute effect and time course of extension and internal rotation stretching of the shoulder on infraspinatus muscle hardness

BACKGROUND

A decrease in flexibility of the infraspinatus muscle causes limitations in the range of shoulder motion. Static stretching (SS) is a useful method to improve muscle flexibility and joint mobility. Previous researchers investigated effective stretching methods for the infraspinatus. However, few researchers investigated the acute effect of SS on the infraspinatus muscle's flexibility. In addition, the minimum SS time required to increase the infraspinatus muscle's flexibility remains unclear. The aims of this study included investigating the acute effect of SS on the infraspinatus muscle's hardness (an index of muscle flexibility) by measuring shear elastic modulus and determining minimum SS time to decrease the infraspinatus muscle's hardness.

METHODS

This included measuring the effect of SS with extension and internal rotation of the shoulder on the infraspinatus muscle's hardness in 20 healthy men. Hence, shear elastic modulus of the infraspinatus was measured by ultrasonic shear wave elastography before and after every 10 seconds up to 120 seconds of SS.

RESULTS

Two-way analysis of variance indicated a significant main effect of SS duration on shear elastic modulus. The post hoc test indicated no significant difference between shear elastic modulus after 10 seconds of SS and that before SS. However, shear elastic modulus immediately after a period ranging from 20 seconds to 120 seconds of SS was significantly lower than that before SS.

CONCLUSION

The results suggested that shoulder extension and internal rotation SS effectively decreased the infraspinatus muscle's hardness. In addition, the results indicated that a period exceeding 20 seconds of SS decreased the infraspinatus muscle's hardness.

Shoulder horizontal abduction stretching effectively increases shear elastic modulus of pectoralis minor muscle

BACKGROUND

Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography.

METHODS

Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver-angle combinations.

RESULTS

The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°.

CONCLUSIONS

This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo.

Assessment of the mechanical properties of the muscle-tendon unit by supersonic shear wave imaging elastography: a review

This review aimed to describe the state of the art in muscle-tendon unit (MTU) assessment by supersonic shear wave imaging (SSI) elastography in states of muscle contraction and stretching, during aging, and in response to injury and therapeutic interventions. A consensus exists that MTU elasticity increases during passive stretching or contraction, and decreases after static stretching, electrostimulation, massage, and dry needling. There is currently no agreement regarding changes in the MTU due to aging and injury. Currently, the application of SSI for the purpose of diagnosis, rehabilitation, and physical training remains limited by a number of issues, including the lack of normative value ranges, the lack of consensus regarding the appropriate terminology, and an inadequate understanding of the main technical limitations of this novel technology.

Effect of scapular stabilization during cross-body stretch on the hardness of infraspinatus, teres minor, and deltoid muscles: An ultrasonic shear wave elastography study

BACKGROUND

Posterior shoulder tightness is a contributing factor to shoulder injuries. Cross-body stretch is a method frequently prescribed to stretch the posterior shoulder structures. This stretching is performed horizontally adducting the shoulder with or without manual stabilization of the scapula by the therapist. However, no studies have investigated the effect of scapular stabilization during cross-body stretch using shear elastic modulus as an index of muscle hardness in vivo.

OBJECTIVES

The aim of this study was to quantitatively examine, using ultrasonic shear wave elastography, whether scapular stabilization during cross-body stretch effectively decreased the hardness of the infraspinatus, the teres minor, or the posterior portion of the deltoid muscles.

DESIGN

A randomized, repeated-measures, cross-over design.

METHOD

Twenty healthy men participated in this study. The shear elastic modulus of the teres minor, the superior and inferior portions of the infraspinatus, and the posterior portion of the deltoid were measured before, and immediately after cross-body stretch with and without scapular stabilization.

RESULTS

The shear elastic modulus of the superior and inferior portions of the infraspinatus decreased significantly after cross-body stretch with scapular stabilization, but there was no significant change in the shear modulus of the measured muscles after cross-body stretch without scapular stabilization.

CONCLUSIONS

Our results suggest that manual scapular stabilization during cross-body stretch effectively decreases the hardness of the infraspinatus muscle.