Chronic changes in muscle architecture and aponeurosis structure following calf muscle strain injuries.

BACKGROUND: Muscle strain injuries in the human calf muscles are frequent sports injuries with high recurrence. Potential structural and functional changes in the medial head of the musculus gastrocnemius (GM) and the associated aponeurosis are not well documented. PURPOSE: To test whether a GM muscle strain injury affects muscle fascicle length, pennation angle, and the morphology of the deep aponeurosis at rest and during muscle contraction long time after the injury. Additionally, electromyography (EMG) of the GM and the soleus muscle during a unilateral heel rise was measured in the injured and uninjured calf. METHODS: GM fascicle length, pennation angle, and aponeurosis thickness was analyzed on dynamic ultrasonography (US) recordings in 10 participants with a chronic calf strain. In addition, US images taken across the distal portion and mid-belly of the GM were analyzed at three different ankle positions. EMG recordings were obtained during a unilateral heel rise. RESULTS: The pennation angle of the injured distal GM was significantly larger compared to the uninjured GM in the contracted, but not the relaxed state. Pennation angle increased more in the injured compared to the uninjured GM during contraction. Fascicle length was shorter in the most distal portion of the injured GM. Fascicles at the distal portion of the injured GM showed a pronounced curvilinear shape as the muscle contracted and the aponeurosis was enlarged in the injured compared to the uninjured GM. The ratio between GM and soleus EMG activity showed a significantly higher relative soleus activity in the injured compared to the healthy calf. CONCLUSION: The greater change in pennation angle and curvilinear fascicle shape during contraction suggest that a long-term consequence after a muscle strain injury is that some muscle fibers at the distal GM are not actively engaged. The significantly enlarged aponeurosis indicates a substantial and long-lasting connective tissue involvement following strain injuries.

Dynamic ultrasound assessment of hip instability and anterior and posterior hip impingement.

OBJECTIVE: In this technical report, we describe our protocol for the dynamic sonographic evaluation of the hip and assess reliability of the ultrasound assessment of hip microinstability. MATERIALS AND METHODS: Our clinical experience with a standardized dynamic ultrasound of the hip performed in a series of 27 patients with imaging performed by an experienced musculoskeletal radiologist during physical examination by an orthopedic surgeon specializing in hip preservation is illustrated with clinical photographs and ultrasound images from volunteers and selected patients. Interrater reliability for the diagnosis of microinstability was calculated. RESULTS: Dynamic ultrasound technique and findings of hip instability, femoroacetabular impingement, and ischiofemoral impingement with corresponding clinical photos showing the necessary physical examination maneuvers are described. Interrater agreement for the diagnosis of microinstability was substantial (κ 0.606 [0.221-0.991]). CONCLUSION: At our institution, dynamic ultrasound of the hip during physical examination complements information gathered from static imaging by providing real-time correlation of symptoms with what is occurring anatomically.

Genetic etiology and pregnancy outcomes of fetuses with central nervous system anomalies.

PURPOSE: To investigate genetic etiology and pregnancy outcomes of fetal central nervous system (CNS) anomalies. METHODS: 217 fetuses with CNS anomalies were included in our cohort from January 2016 to December 2022. 124 cases received karyotyping and 73 cases simultaneously underwent copy number variant sequencing (CNV-seq). Dynamic ultrasound screening and pregnancy outcomes were followed up, including neonates' neurodevelopmental outcomes. RESULTS: (1) 20 types of CNS anomalies were revealed by ultrasound and the most common was ventriculomegaly. (2) 14 (11.3%) of 124 cases were found chromosomal abnormalities by karyotyping, and copy number variations (CNVs) were revealed in 13 (17.8%) of 73 cases by CNV-seq. Fetuses with non-isolated CNS anomalies had a higher detection rate (DR) of abnormal karyotypes and CNVs than those with isolated CNS anomalies (25.0% vs. 4.8%; 35.0% vs. 11.3%) (P < 0.05). And the DR of abnormal karyotypes was significantly higher in multiple CNS anomalies than in single CNS anomaly (16.7% vs. 2.8%, P < 0.05), while there were no significant differences in the DR of CNVs. (3) Through dynamic ultrasound, 12 cases were further found progression or additional malformations. (4) Pregnancy outcomes of 209 cases were obtained, including 136 (65.1%) live births, 3 (1.4%) intrauterine fetal deaths, and 70 (33.5%) terminated. Two neonatal deaths at 6 months and one infant with motor and intellectual disabilities were finally found after long-term follow-up. CONCLUSION: Genetic analysis combined with dynamic ultrasound screening and multidisciplinary consultation plays an important role in evaluating the prognosis of fetal CNS anomalies, especially for those with multiple CNS or extracranial abnormalities.

Urethral support in female urinary continence part 1: dynamic measurements of urethral shape and motion.

INTRODUCTION AND HYPOTHESIS: Urethral closure mechanism dysfunction in female stress urinary incontinence (SUI) is poorly understood. We aimed to quantify these mechanisms through changes in urethral shape and position during squeeze (voluntary closure) and Valsalva (passive closure) via endovaginal ultrasound in women with varying SUI severity. METHODS: In this prospective cohort study, 76 women who presented to our tertiary center for urodynamic testing as preoperative assessment were recruited. Urodynamics were performed according to International Continence Society criteria. Urethral pressures were obtained during serial Valsalva maneuvers. Urethral lengths, thicknesses, and angles were measured in the midsagittal plane via dynamic anterior compartment ultrasound. Statistical shape modeling was carried out by a principal component analysis on aligned urethra shapes. RESULTS: Age, parity, and BMI did not vary by SUI group. Ultrasound detected a larger retropubic angle, urethral knee-pubic bone angle (a novel measure developed for this study), and infrapubic urethral length measurements at Valsalva in women with severe SUI (p = 0.016, 0.015, and 0.010). Shape analysis defined increased "c" shape concavity and distal wall pinching during squeeze and increased "s" shape concavity and distal wall thickening during Valsalva (p < 0.001). It also described significant urethral shape differences across SUI severity groups (p < 0.001). CONCLUSIONS: Dynamic endovaginal ultrasound can visualize and allow for quantification of voluntary and passive urethral closure and variations with SUI severity. In women with severe SUI, excessive bladder neck and distal urethra swinging during Valsalva longitudinally compressed the urethra, resulting in a proportionally thicker wall at the mid-urethra and urethral knee.

Generalized Joint Laxity Is Associated With Dynamic Hip Ultrasonography Measures in Female Athlete Patients Who Are Not Hypermobile.

OBJECTIVES: To investigate ultrasound (US) femoroacetabular translation measurements in female athlete patients. METHODS: A prospective cross-sectional study was conducted in female athlete patients <50 years. Demographic data, Beighton score/hypermobility status, and sport participation were collected. Hip dysplasia was determined using radiographic measurements (lateral center edge angle, anterior center edge angle, Tönnis angle); femoral version angles were measured with CT or MR. Femoroacetabular translation US measures included neutral (N), neutral flexed (NF), extension external rotation/apprehension (EER) positions. Maximal difference (delta) between US measures was calculated. RESULTS: 206/349 female hips were analyzed (median age 21.2 years [range, 12-49.5]). The primary sport group was performing arts (45%, 92/206). Mean Beighton score was 5.2 (SD, 2.5) with 61% (129/206) of hips exhibiting hypermobility (Beighton score ≥5). For each additional unit of Beighton score, N US measurement increased by 0.7 mm (ß = 0.7; 95% confidence interval [CI] = 0.22-1.25; P < .001), NF by 1 mm ( ß = 0.9; 95% CI = 0.3-1.43; P = .002) and EER by 0.8 mm ( ß = 0.8; 95% CI = 0.27-1.37; P < .001) when adjusting for age and dysplasia status. A positive correlation was detected between NF (r = 0.19; 95% CI = 0.05-0.33; P = .007) and EER (r = 0.19; 95% CI = 0.05-0.32; P = .01) with Tönnis angle and a negative correlation between the delta and femoral version (r = -0.20; 95% CI = -0.35 to 0.03; P = .02). No difference in US measures was detected across sport groups (N [P = .24], NF [P = .51], EER [P = .20], delta [P = .07]). CONCLUSION: Beighton score was independently associated with dynamic US measures in female athlete patients who are not hypermobile when controlling for other factors.

Localized tenosynovial giant cell tumor: a rare case of snapping hip.

We report on a 40-year-old male with a 9-month-long history of snapping of his right hip caused by a previously undescribed etiology of internal extra-articular snapping hip, namely due to a localized tenosynovial giant cell tumor. Both dynamic ultrasound evaluation and MRI proved to be crucial in the diagnosis of this rare entity. Auto-provocation of the snapping showed an anterior hip mass moving posteriorly to the psoas tendon which elucidated the pain and clicking sensation. Subsequent MRI demonstrated a peripheral low-intensity rim due to hemosiderin deposition around the synovial mass which is indicative for pigmented villonodular tenosynovitis. Treatment consisted of arthroscopic shaver burr resection. Immediately postoperatively, the snapping sensation could not be provoked anymore by the patient. The purpose of reporting on this case report is to emphasize several successive learning points. First, dynamic ultrasound aids in diagnosis and differentiation of the types of snapping hip. Second, specific MRI features are suggestive of tenosynovial giant cell tumor, recognizing these traits may prevent delayed diagnosis and subsequent aggravated clinical course. Third, localized pigmented villonodular tenosynovitis around the hip may present as an internal extra-articular snapping hip and is of consideration in the differential diagnosis of recurrent snapping hip.

Posttraumatic cicatricial sciatic nerve entrapment: dynamic imaging and percutaneous neurolysis.

We describe a case of late-onset sciatic neuralgia due to cicatricial tethering of the sciatic nerve by a retracted torn hamstring muscle that was successfully treated with percutaneous neurolysis. Ultrasound and MRI showed a chronic complete avulsion of the proximal hamstring complex with fatty atrophy of the retracted hamstring muscles. Dynamic ultrasound and magnetic resonance imaging displayed tethering of the retracted hamstring complex to the sciatic nerve caused by cicatricial adhesions. Whereas hamstring injuries are highly prevalent sports injuries, there are only a small number of reported cases in the literature of late-onset sciatic nerve involvement. We highlight the benefits of dynamic ultrasound and magnetic resonance imaging and propose ultrasound-guided percutaneous neurolysis as a viable minimally invasive treatment option.

Sonographic evaluation of lateral meniscal extrusion: implementation and validation.

INTRODUCTION: Meniscal extrusion (ME) is an important indicator of and prognostic factor for various knee pathologies. To date, no standardized protocol for the ultrasound-based examination of lateral ME exists. The purpose of the present study was to test the reliability and validity of lateral ME measurements using a standardized ultrasound-based examination protocol. MATERIALS AND METHODS: A group consisting of 11 healthy volunteers (Group I, male and female, 18-45 years) as well as a group of 10 consecutive patients who had undergone all-inside lateral meniscal radial tear repair were included (Group II, male and female, 23-43 years). Lateral ME, the main outcome parameter, was measured by ultrasound (US; both groups) and magnetic resonance imaging (MRI; Group II only). Both knees of all subjects were examined in an unloaded state and under axial compression of the knee (50% of body weight). Repeated measurements obtained in Group I by 2 observers were used for reliability testing, and the validity of US was assessed through comparison with MRI data (Group II). RESULTS: A total of 66 US images of Group I, obtained by each observer, were analyzed for reliability testing. Forty US and MR images of Group II were assessed for validation. Results showed good interrater (ICC = 0.904) and excellent intrarater (ICC = 0.942) reliability of US-based measurements of lateral ME. Agreement with MRI results was poor (ICC = 0.439), with US systematically overestimating results by 1.1 mm on average. CONCLUSIONS: Ultrasound is a reliable, quick and cost-effective technique for lateral ME measurement, but results are not readily comparable with MRI. TRIAL REGISTRATION: The study was registered in the European Union Clinical Trials Register (EudraCT-Number: 2017-005037-24).

Location-dependent change of median nerve mobility in the carpal tunnel of patients with carpal tunnel syndrome.

INTRODUCTION: The purpose of this study was to investigate in vivo median nerve longitudinal mobility in different segments of the carpal tunnel associated with active finger motion in carpal tunnel syndrome (CTS) patients in a comparison with healthy controls. METHODS: Eleven healthy volunteers and 11 CTS patients participated in this study. Dynamic ultrasound images captured location-dependent longitudinal median nerve mobility within the carpal tunnel during finger flexion at the metacarpophalangeal joints using a speckle cross-correlation algorithm. RESULTS: Median nerve longitudinal mobility in the carpal tunnel was significantly smaller in CTS patients (0.0037 ± 0.0011 mm/degree) compared with controls (0.0082 ± 0.0026 mm/degree) (P < .05), especially in the proximal (0.0064 vs 0.0132 mm/degree on average) and middle (0.0033 vs 0.0074 mm/degree on average) carpal tunnel sections. DISCUSSION: Median nerve mobility can potentially serve as a biomechanical marker when diagnosing CTS, or when assessing the effectiveness of surgical and conservative treatments.

Evaluation of Dynamic Ultrasound for Arterial Access in Children Undergoing Cardiac Surgery.

OBJECTIVE: To evaluate the effect of dynamic ultrasound (US) on the need for surgical intervention to achieve successful arterial cannulation in the pediatric cardiac surgery population. DESIGN: Retrospective, observational study. SETTING: Single, academic, pediatric hospital in the United States. PARTICIPANTS: The study comprised 3,569 consecutive patients who had an arterial catheter placed in the operating room before undergoing congenital heart surgery between January 2004 and September 2016. INTERVENTIONS: Dynamic US was used in 2,064 cases (57.83%) to obtain arterial access. Arterial cannulation by palpation was performed in the remaining 37.8% of cases. Surgical cutdown for arterial access was required in 192 cases after failed cannulation attempts by the anesthesia team. MEASUREMENTS AND MAIN RESULTS: Use of US was associated with an overall decrease in the need for surgical access from 10.43% to 1.70% (p < 0.0001). In patients younger than 30 days, US decreased the rate of surgical access, from 19.62% to 2.65% (p < 0.0001). This significant decrease also was observed in patients 1 to 6 months old (13.93% v 3.73%; p < 0.0001), 7 to 12 months old (7.34% v 0.00%, p < 0.0001), and older than 2 years (1.12% v 0%; p = 0.0083). For children between 13 and 24 months old, there was no statistically significant benefit to using US for avoiding surgical access (3.33% v 0.79%; p = 0.1411). Throughout all age groups, use of US was associated with a significant improvement in optimal arterial line location, defined as placement in an upper extremity (73.75% v 91.13%; p < 0.0001). CONCLUSIONS: Dynamic US resulted in a significant reduction in surgical intervention to achieve arterial cannulation in children presenting for cardiac surgery.

Correlation Between Medial Meniscal Extrusion Determined by Dynamic Ultrasound and Magnetic Resonance Imaging Findings of Medial-Type Knee Osteoarthritis in Patients With Knee Pain.

OBJECTIVES: The aim of our study was to investigate the relationship between medial meniscal extrusion (MME) determined by dynamic ultrasound (US) and magnetic resonance imaging findings of medial-type knee osteoarthritis (OA). METHODS: Single knees of 102 patients with knee pain were assessed by radiography, dynamic US, and magnetic resonance imaging. All knee radiographs were interpreted and grouped according to the Kellgren-Lawrence (KL) scale. Medial meniscal extrusion in non-weight-bearing and weight-bearing positions and the difference of these values (ΔMME) were measured by dynamic US. The medial tibiofemoral compartments of all knees were evaluated and grouped according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Mean values of non-weight-bearing MME, weight-bearing MME, and ΔMME ± standard deviations for groups formed according to the KL scale and WORMS system were compared. RESULTS: We demonstrated that different from non-weight-bearing MME, weight-bearing MME was significantly correlated with not only high grades but also lower grades of cartilage damage and subchondral bone marrow lesions in medial-type knee OA. Although the difference in non-weight-bearing MME between cartilage status groups 1 and 2 was not significant (P = .071), there were significant differences in of weight-bearing MME between groups 1 and 2, between groups 2 and 3, and between groups 3 and group 4 (P = .003, .002, and .032, respectively). CONCLUSIONS: We found statistically significant associations between MME values and the severity of the OA findings according to both the KL scale and WORMS system. We offer dynamic US as an initial tool for the diagnosis and a screening method to estimate the severity of knee OA.

Dynamic ultrasound in the evaluation of patients with suspected slipping rib syndrome.

OBJECTIVE: Slipping rib syndrome (SRS) affects adolescents and young adults. Dynamic ultrasound plays a potential and likely significant role; however, limited data exist describing the protocol and techniques available. It is our intent to describe the development of a reproducible protocol for imaging in patients with SRS. MATERIALS AND METHODS: Retrospective review of suspected SRS patients from March 2017 to April 2018. A total of 46 patients were evaluated. Focused history and imaging was performed at the site of pain. Images of the ribs were obtained in the parasagittal plane at rest and with dynamic maneuvers. Dynamic maneuvers included Valsalva, crunch, rib push maneuver, and any provocative movement that elicited pain. Imaging was compared with records from the pediatric surgeon specializing in slipping ribs. Statistical analysis was performed. RESULTS: Thirty-six of the 46 patients had a diagnosis of SRS, and had an average age of 17 years. Thirty-one patients were female, 15 were male. Thirty-one out of 46 (67%) were athletes. Average BMI was 22.6. Dynamic ultrasound correctly detected SRS in 89% of patients (32 out of 36) and correctly detected the absence in 100% (10 out of 10). Push maneuver had the highest sensitivity (87%; 0.70, 0.96) followed by morphology (68%; 0.51, 0.81) and crunch maneuver (54%; 0.37, 0.71). Valsalva was the least sensitive (13%; 0.04, 0.29). CONCLUSION: Dynamic ultrasound of the ribs, particularly with crunch and push maneuvers, is an effective and reproducible tool for diagnosing SRS. Valsalva plays a limited role. In addition to diagnosing SRS, ultrasound can give the surgeon morphological data and information on additional ribs at risk, thereby assisting in surgical planning.

The Use of Preoperative Dynamic Ultrasound to Predict Ulnar Nerve Stability Following In Situ Decompression for Cubital Tunnel Syndrome.

PURPOSE: To assess the use of preoperative, dynamic ultrasound to predict ulnar nerve instability following in situ decompression for cubital tunnel syndrome. METHODS: Prior to undergoing in situ decompression, 43 consecutive patients underwent dynamic ultrasound to assess the stability of the ulnar nerve during elbow flexion. The dynamic ultrasound findings were compared with the intraoperative assessment of nerve stability following in situ decompression. RESULTS: The preoperative dynamic ultrasound agreed with intraoperative findings in 38 of 43 patients (88%). Physical examination of ulnar nerve stability agreed with the intraoperative findings in 5 of 43 patients (12%). For the 5 of 43 cases in which the dynamic ultrasound did not correlate with the degree of ulnar nerve stability after in situ decompression, dynamic ultrasound overestimated the degree of ulnar nerve stability in 4 cases. CONCLUSIONS: Preoperative dynamic ultrasound can be used to accurately predict the degree of ulnar nerve instability following in situ decompression. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Medial elbow stability assessment after ultrasound-guided ulnar collateral ligament transection in a cadaveric model: ultrasound versus stress radiography.

BACKGROUND: The ulnar collateral ligament (UCL), consisting of 3 bundles, is the primary medial restraint in the elbow. Recent research has demonstrated that ultrasound is an effective modality to evaluate the medial elbow, whereas stress radiography is standard practice in the measurement of medial elbow laxity. This study (1) compared dynamic ultrasound (USD) with stress radiography in the evaluation of UCL insufficiency and (2) further evaluated the contribution of the anterior bundle of the UCL to medial elbow stability. METHODS: Stress radiographs and USD were used to obtain coronal plane measurements of the medial joint space of 16 cadaveric elbows before and after USD-guided isolated transection of the anterior bundle of the UCL. Measurements were performed with and without a valgus stress applied to the elbows, and gapping of the ulnohumeral joint space was documented. RESULTS: Transection of the anterior bundle of the UCL resulted in 1.5 mm and 1.7 mm of additional gapping in the ulnohumeral joint as measured with stress radiographs and USD, respectively. No differences were recorded in the ulnohumeral gapping measurements between stress radiography and USD. CONCLUSIONS: The lack of difference between measurements reveals USD is as reliable as stress radiography in evaluating the medial ulnohumeral joint space and continuity of the UCL while eliminating radiation exposure and minimizing cost of the diagnostic examination. The increase in ulnohumeral gapping with isolated transection of the anterior bundle of the UCL demonstrates its significant contribution to medial elbow stability.

Not all sagittal band tears come with extensor instability: a case report with radiological and operative correlation.

The sagittal bands are a component of the extensor hood. They serve an important role in stabilizing the extensor tendon by forming a "check-rein" to radial-ulnar translation of the tendon over the metacarpal head, and extending the metacarpophalangeal (MCP) joint by virtue of attaching the extensor tendon to the palmar plate. Injury to the sagittal band is thought to cause extensor instability and subluxation to the contralateral side by disruption of this "check-rein" function, although recent evidence from cadaver studies suggests that ulnar sagittal band tear may be spared of extensor instability. As a case in point, we encountered a patient with surgically proven ulnar sagittal band tear, who did not have any extensor tendon subluxation or any limitation in motion. Intraoperative findings demonstrated a chronic-appearing ulnar sagittal band tear, indicating that chronic injury with fibrosis may stabilize the central band. Therefore, in patients with metacarpophalangeal pain without central tendon subluxation or limitation of motion, it remains important to raise the concern of sagittal band tear for appropriate treatment. We present the clinical course of this case, with radiological and operative findings, followed by a review of the relevant literature.

Early dynamic ultrasound for neonatal hip instability: implications for rural Australia.

BACKGROUND: Neonatal instability of the hip (NIH), where the femoral head can move away from the acetabulum, in the first weeks of life, is an important risk factor for developmental dysplasia of the hip (DDH). In rural areas in Australia, there is a recent trend to increased late diagnosis of DDH. Clinical screening of infant hips, a common practice in Australia, is experience dependent. Best practice early screening techniques are still debated with different techniques and timing used internationally. This systematic review examines early dynamic ultrasound (eDUS) screening for hip instability in the first 6 weeks after birth, and the early interventions informed by these findings and considers the findings for the context of rural Australia. METHODS: The Cochrane Library, Medline, CINAHL and PEDro were searched for original research or systematic reviews, and clinical studies 1998 to 2015 involving dynamic ultrasound. Critical Appraisal Skills Programme tools were used to appraise the studies. RESULT: Nineteen studies were included. Early Dynamic Ultrasound (DUS) is consistently described as a reliable assessment of NIH. Early DUS is recommended for risk factors including geographical areas of high prevalence. Approaches to early intervention of hips with excessive movement are somewhat discipline-related and include: primary prevention (advice), secondary prevention (abduction supports), and conservative management (removable splints). CONCLUSIONS: In the context of increased prevalence of DDH in rural Australia, contemporary evidence suggests that introduction of early DUS could provide rural infants with more effective screening than clinical examination alone. Targeted early advice about posturing and simple removable supports to abduct infant hips could prevent some cases of DDH in rural Australia.

Dorsal Wrist Carpal Boss Impingement-Dynamic Ultrasound to the Rescue!

The "carpal boss" is a variant present in 19% of the population according to cadaveric studies but becomes symptomatic in only 1% of cases. With the rising popularity of "yoga," which includes prolonged hyperextension at the wrist joint with weight bearing, an increasing number of individuals with silent carpal boss present with dorsal wrist pain due to impingement over the dorsal soft tissues by this innocuous bony protuberance. This warrants the attention of radiologists and clinicians while dealing with wrist pain. It can be challenging to identify this bossing on routine radiographs, necessitating special views. We describe the use of dynamic ultrasound in diagnosing "symptomatic" carpal boss, the effects of which become even more evident on imaging during hyperextension-the triggering movement.

Quantitative pulsatility measurements using 3D dynamic ultrasound localization microscopy.

A rise in blood flow velocity variations (i.e. pulsatility) in the brain, caused by the stiffening of upstream arteries, is associated with cognitive impairment and neurodegenerative diseases. The study of this phenomenon requires brain-wide pulsatility measurements, with large penetration depth and high spatiotemporal resolution. The development of dynamic ultrasound localization microscopy (DULM), based on ULM, has enabled pulsatility measurements in the rodent brain in 2D. However, 2D imaging accesses only one slice of the brain and measures only 2D-projected and hence biased velocities . Herein, we present 3D DULM: using a single ultrasound scanner at high frame rate (1000-2000 Hz), this method can produce dynamic maps of microbubbles flowing in the bloodstream and extract quantitative pulsatility measurements in the cat brain with craniotomy and in the mouse brain through the skull, showing a wide range of flow hemodynamics in both large and small vessels. We highlighted a decrease in pulsatility along the vascular tree in the cat brain, which could be mapped with ultrasound down to a few tens of micrometers for the first time. We also performed an intra-animal validation of the method by showing consistent measurements between the two sides of the Willis circle in the mouse brain. Our study provides the first step towards a new biomarker that would allow the detection of dynamic abnormalities in microvessels in the brain, which could be linked to early signs of neurodegenerative diseases.

Using dynamic ultrasound to assess Achilles tendon mechanics during running: The effect on running pattern and muscle-tendon junction tracking.

Achilles tendon strain can be quantified using dynamic ultrasound, but its use in running is limited. Minimal effects on running pattern and acceptable test-retest reliability of muscle-tendon junction (MTJ) tracking are prerequisites for ultrasound use during running. We aimed to assess (i) the effect of wearing an ultrasound transducer on running pattern and (ii) the test-retest reliability of MTJ tracking during running. Sixteen long-distance runners (nine injury-free, seven with Achilles tendinopathy) ran at different speeds on an instrumented treadmill with a 10-camera system tracking skin-mounted retroreflective markers, first without and then with an ultrasound transducer attached to the lower leg to track the MTJ of the gastrocnemius medialis. Spatiotemporal parameters, joint kinematics and kinetics were compared between conditions using mixed ANOVAs and paired t-tests. MTJ tracking was performed manually twice by three raters in ten participants. Variability and standard error of measurement (SEM) quantified the inter- and intra-tester test-retest reliability. The running pattern was not affected by wearing the ultrasound transducer, except for significantly less knee flexion during midstance (1.6°) and midswing (2.9°) found when wearing the transducer. Inter-rater and intra-rater SEMs for MTJ tracking to assess the tendon strain (0.43%, and 0.56%, respectively) were about four times as low as between-group differences presented in literature. The minimal effects found on the running pattern and acceptable test-retest reliability indicates that dynamic ultrasound during running can be appropriately used to study Achilles tendon mechanics and thereby help improve our understanding of Achilles tendon behavior during running, injury development and recovery.

Evaluation under loading detects medial meniscus extrusion in patients with reconstructed anterior cruciate ligament and restricted knee extension.

PURPOSE: Some patients who undergo anterior cruciate ligament (ACL) reconstruction experience abnormal mechanical stress in the meniscus. Medial meniscal extrusion (MME) is reflected in the pathological condition of the meniscus, which expands owing to repetitive mechanical stress. Thus, the effect of the reconstructed ACL on increasing MME under weight-bearing conditions remains unclear. This study investigated the effect of ACL reconstruction on meniscal extrusion under non-weight-bearing and weight-bearing conditions. METHODS: Seventeen patients who underwent unilateral ACL reconstruction (ACL group) and 20 age-matched healthy volunteers (control group) were enrolled. Ultrasonography was performed in the supine, standing, and walking positions in preoperative and postoperative ACL patients. MME during walking was evaluated based on the dynamic behavior of extrusion, and kinetic and kinematic data were synchronously obtained. Moreover, the ACL group underwent magnetic resonance imaging (MRI) evaluation at two points: preoperatively and 12 months postoperatively, and the ultrasound findings were compared. RESULTS: MME in the supine position measured using both ultrasonography and MRI was not significantly different preoperatively and postoperatively in the ACL group. However, postoperative MME and dynamic behavior of extrusion under standing and walking conditions were significantly higher than those in the preoperative state (dynamic behavior: 0.9 ± 0.4 mm preoperatively, 1.2 ± 0.4 mm postoperatively). Moreover, the deficits in knee extension during walking persisted postoperatively and were significantly higher than those in the control group. CONCLUSION: MME in patients with ACL reconstruction including meniscus repair was different under mechanical stress compared to the non-weight bearing condition.