2D and 3D microstructural analysis of the iliotibial tract.

The fascial system has gained recognition for its integral role in connecting skin, superficial and deep fasciae, and underlying muscles. However, consensus on its microstructure depending on its topography remains elusive as well as its implications in clinical practices, such as reconstructive surgery and physiotherapy techniques. This study focuses on the iliotibial tract (ITT) implicated in the iliotibial band syndrome. The goal is to describe microstructural characteristics using classical 2D histology and cryogenic contrast-enhanced microcomputed tomography (cryo-CECT) such as the total thickness, number of layers, layer thickness, fibre orientation and tortuosity, according to the specific topography. The total thickness of the ITT varied across topographic regions, with the superior part being on average thicker but non-significantly different from the other regions. The inferior part showed heterogeneity, with the anterior region (AI) being the thinnest and the posterior one (PI) the thickest. The ITT exhibited 1-3 layers, with no significant differences among regions. Most commonly, it consisted of two layers, except for the antero-superior (AS) and antero-middle (AM) regions, which sometimes had only one layer. The posterior regions frequently had 2 or 3 layers, with the PI region having the highest mean (2.7 layers). The intermediate layer was the thickest one, varying from the AI region (0.368 mm ± 0.114) to the PI region (0.640 mm ± 0.305). The superficial layer showed regional variability, with the AS region being the thinnest. The deep layer appeared thinner than the superficial one. Fibre orientation analysis indicated that the intermediate layer mainly consisted of oblique longitudinal fibres, orientated downward and forward, while the superficial and deep layers had transversal or oblique transversal fibres. Cryo-CECT 3D observations confirmed these findings, revealing distinct orientations for different layers. Fibre tortuosity exhibited differences based on orientation. Transversal fibres (>65°) were significantly less tortuous than longitudinal fibres (<25°) and oblique intermediate fibres (25°-65°), aligning with 3D plot observations. This quantitative study highlights various microstructural characteristics of the ITT, offering insights into its regional variations. The analysis accuracy is increased due to the novel technology of cryo-CECT which emerges as a valuable tool for precise assessment of 3D fibre orientation and tortuosity. These findings contribute to a deeper understanding of the ITT structure, useful in clinical practices, such as reconstructive surgery and physiotherapy, and future research endeavours.

Injuries to the anterolateral ligament are observed more frequently compared to lesions to the deep iliotibial tract (Kaplan fibers) in anterior cruciate ligamant deficient knees using magnetic resonance imaging.

PURPOSE: To determine the accuracy of detection, injury rate and inter- and intrarater reproducibility in visualizing lesions to the anterolateral ligament (ALL) and the deep portion of the iliotibial tract (dITT) in anterior cruciate ligament (ACL) deficient knees. METHODS: Ninety-one consecutive patients, out of those 25 children (age 14.3 ± 3.5 years), with diagnosed ACL tears were included. Two musculoskeletal radiologists retrospectively reviewed MRI data focusing on accuracy of detection and potential injuries to the ALL or dITT. Lesion were diagnosed in case of discontinued fibers in combination with intra- or peri-ligamentous edema and graded as intact, partial or complete tears. Cohen's Kappa and 95% confidence intervals (95% CI) were determined for inter- and intrarater reliability measures. RESULTS: The ALL and dITT were visible in 52 (78.8%) and 56 (84.8%) of adult-and 25 (100%) and 19 (76.0%) of pediatric patients, respectively. The ALL was injured in 45 (58.5%; partial: 36.4%, compleate: 22.1%) patients. Partial and comleate tears, where visualized in 21 (40.4%) and 16 (30.8%) adult- and seven (28.0%) and one (4%) peditric patients. A total of 16 (21.3%; partial: 13.3%, compleate: 8.0%) dITT injuries were identified. Partal and complete lesions were seen in seven (12.5%) and five (8.9%) adult- and three (15.8%) and one (5.3%) pediatric patients. Combined injuries were visualized in nine (12.7%) patients. Inter-observer (0.91-0.95) and intra-observer (0.93-0.95) reproducibility was high. CONCLUSION: In ACL injured knees, tears of the ALL are observed more frequently compared to lesions to the deep iliotibial tract. Combined injuries of both structures are rare. Clinically, the preoperative visualization of potentially injured structures of the anterolateral knee is crucial and is important for a more personalized preoperative planning and tailored anatomical reconstruction. The clinical implication of injuries to the anterolateral complex of the knee needs further investigation. LEVEL OF EVIDENCE: II.

Tensor fasciae latae muscle in human embryos and foetuses with special reference to its contribution to the development of the iliotibial tract.

BACKGROUND: The human tensor fasciae latae muscle (TFL) is inserted into the iliotibial tract and plays a critical role in lateral stabilisation of the hip joint. We previously described a candidate of the initial iliotibial tract that originated from the gluteus maximus muscle and extended distally. MATERIALS AND METHODS: This study extended our observations by examining 30 human embryos and foetuses of gestational age (GA) 7-14 weeks (crown-to-rump length 24-108 mm). At GA 7 weeks, the TFL appeared as a small muscle mass floating in the subcutaneous tissue near the origins of the gluteus medius and rectus femoris muscles. RESULTS: Subsequently, the TFL obtained an iliac origin adjacent to the rectus femoris tendon, but the distal end remained a tiny fibrous mass on the vastus lateralis muscle. Until GA 10 weeks, the TFL muscle fibres were inserted into a vastus lateralis fascia that joined the quadriceps tendon distally. The next stage consisted of the TFL muscle belly "connecting" the vastus fascia and the gluteus fascia, including our previous candidate of the initial iliotibial tract. Until GA 14 weeks, the TFL was sandwiched by two laminae of the connecting fascia. CONCLUSIONS: These findings suggested that, when the vastus lateralis fascia separated from the quadriceps tendon to attach to the tibia, possibly after birth, the resulting iliotibial tract would consist of a continuous longitudinal band from the gluteus maximus fascia, via the vastus fascia, to the tibia. Although it is a small muscle, the foetal TFL plays a critical role in the development of the iliotibial tract.

Foetal development of the human gluteus maximus muscle with special reference to its fascial insertion.

The human gluteus maximus muscle (GMX) is characterised by its insertion to the iliotibial tract (a lateral thick fascia of the thigh beneath the fascia lata), which plays a critical role in lateral stabilisation of the hip joint during walking. In contrast, in non-human primates, the GMX and biceps femoris muscle provide a flexor complex. According to our observations of 15 human embryos and 11 foetuses at 7-10 weeks of gestation (21-55 mm), the GMX anlage was divided into 1) a superior part that developed earlier and 2) a small inferior part that developed later. The latter was adjacent to, or even continuous with, the biceps femoris. At 8 weeks, both parts inserted into the femur, possibly the future gluteal tuberosity. However, depending on traction by the developing inferior part as well as pressure from the developing major trochanter of the femur, most of the original femoral insertion of the GMX appeared to be detached from the femur. Therefore, at 9-10 weeks, the GMX had a digastric muscle-like appearance with an intermediate band connecting the major superior part to the small inferior mass. This band, most likely corresponding to the initial iliotibial tract, extended laterally and distally far from the muscle fibres. The fascia lata was still thin and the tensor fasciae latae seemed to develop much later. It seems likely that the evolutionary transition from quadripedality to bipedality and a permanently upright posture would require the development of a new GMX complex with the iliotibial tract that differs from that in non-human primates. (Folia Morphol 2018; 77, 1: 144-150).

The iliotibial tract: imaging, anatomy, injuries, and other pathology.

The iliotibial tract, also known as Maissiat's band or the iliotibial band, and its associated muscles function to extend, abduct, and laterally rotate the hip, as well as aid in the stabilization of the knee. A select group of associated injuries and pathologies of the iliotibial tract are seen as sequela of repetitive stress and direct trauma. This article intends to educate the radiologist, orthopedist, and other clinicians about iliotibial tract anatomy and function and the clinical presentation, pathophysiology, and imaging findings of associated pathologies. Specifically, this article will review proximal iliotibial band syndrome, Morel-Lavallée lesions, external snapping hip syndrome, iliotibial band syndrome and bursitis, traumatic tears, iliotibial insertional tendinosis and peritendonitis, avulsion fractures at Gerdy's tubercle, and Segond fractures. The clinical management of these pathologies will also be discussed in brief.

The deep layer of the tractus iliotibialis and its relevance when using the direct anterior approach in total hip arthroplasty: a cadaver study.

INTRODUCTION: Surgical approaches through smaller incisions reveal less of the underlying anatomy, and therefore, detailed knowledge of the local anatomy and its variations is important in minimally invasive surgery. The aim of this study was to determine the location, extension, and histomorphology of the deep layer of the iliotibial band during minimally invasive hip surgery using the direct anterior approach (DAA). MATERIALS AND METHODS: The morphology of the iliotibial tract was determined in this cadaver study on 40 hips with reference to the anterior superior iliac spine and the tibia. The deep layer of the tractus iliotibialis was exposed up to the hip-joint capsule and length and width measurements taken. Sections of the profound iliotibial tract were removed from the hips and the thickness of the sections was determined microscopically after staining. RESULTS: The superficial tractus iliotibialis had a length of 50.1 (SD 3.8) cm, while tensor fasciae latae total length was 18 (SD 2) cm [unattached 15 (SD 2.5) cm]. Length and width of the deep layer of the tractus iliotibialis were 10.4 (SD 1.3) × 3.3 (SD 0.6) cm. The deep iliotibial band always extended from the distal part of the tensor fascia latae (TFL) muscle to the lateral part of the hip capsule (mean maximum thickness 584 µm). Tractus iliotibialis deep layer morphology did not correlate to other measurements taken (body length, thigh length, and TFL length). CONCLUSIONS: The length of the deep layer is dependent on the TFL, since the profound part of the iliotibial band reaches from the TFL to the hip-joint capsule. The deep layer covers the hip-joint capsule, rectus, and lateral vastus muscles in the DAA interval. To access the precapsular fat pad and the hip-joint capsule, the deep layer has to be split in all approaches that use the direct anterior interval.

Complex function of the knee joint: the current understanding of the knee.

Since the early years of orthopaedics, it is a well-known fact that anatomy follows function. During the evolution of mankind, the knee has been optimally adapted to the forces and loads acting at and through the knee joint. However, anatomy of the knee joint is variable and the only constant is its complex function. In contrast to the time of open surgery, nowadays the majority of reconstructive knee surgery is done arthroscopically. Keyhole surgery is less invasive, but on the backside, the knee surgeon lacks daily visualisation of the complex open anatomy. As open anatomical knowledge is less present in our daily practice, it is even more important to highlight this complex anatomy and function of the knee. It is the purpose of this review to perform a systematic review of knee anatomy, highlight the complex function of the knee joint and present an overview about recent and current knowledge about knee function. Level of evidence Systematic review, Level IV.

Change in gliding properties of the iliotibial tract in hypermobile Ehlers-Danlos Syndrome.

PURPOSE: Fascial changes in hypermobile Ehlers-Danlos syndrome (hEDS), a heritable connective tissue disorder, can be used visualized with sonoelastography. The purpose of this study was to explore the inter-fascial gliding characteristics in hEDS. METHODS: In 9 subjects, the right iliotibial tract was examined with ultrasonography. Tissue displacements of the iliotibial tract were estimated from ultrasound data using cross-correlation techniques. RESULTS: In hEDS subjects, shear strain was 46.2%, lower than those with lower limb pain without hEDS (89.5%) and in control subjects without hEDS and without pain (121.1%). CONCLUSION: Extracellular matrix changes in hEDS may manifest as reduced inter-fascial plane gliding.

Isolated pathologies of Tensor Fasciae Latae: Retrospective cohort analysis from a tertiary referral centre.

Introduction: Tensor Fasciae Latae (TFL) and the iliotibial band (ITB) act as a single functional unit in maintaining pelvic stability whilst standing, walking, or running in human beings. The Tensor Fasciae Latae (TFL) muscle acts across the hip and the knee joint. Consequently, though its pathologies traditionally present with lateral hip pain, identifying the precise clinical diagnosis can be a challenge. Patients and methods: A retrospective search for the keyword 'Tensor Fasciae Latae'/iliotibial band (ITB) was performed of our Radiology Information System (RIS) and Picture Archiving and Communication System (PACS), Computerised Radiology Information System (CRIS) at our tertiary orthopaedic referral centre of a for orthopaedic oncology over a period of 13 years (2007-2020). Data was collected from RIS, oncology database and local histopathology laboratory records. Patient demographics, clinical characteristics, complementary imaging and clinical management outcome were documented. Results: We identified 35 patients with a mean age of 66 years (range 19-94 years). There were 18 female and 17 male patients. Lateral hip lump and pain were the most frequent clinical finding/presentation features. A variety of pathologies such as benign and malignant tumours, including vascular and tumour mimic lesions involving the TFL muscle were identified. Atrophy and pseudohypertrophy of TFL was the commonest pathology found; accounting for two thirds of the cases. Conclusion: Tensor Fasciae Latae (TFL) can be afflicted with a broad spectrum of pathologies. Radiological imaging especially cross-sectional imaging modality is crucial in guiding appropriate patient management of TFL conditions. Our analysis suggests isolated TFL lesion are more likely to be benign conditions, presenting commonly as hip pain and swelling.

Knee Flexion Angle Following Total Knee Arthroplasty Relates to a Preoperative Range of Motion of the Hip.

BACKGROUND: Many factors have been reported to affect postoperative range of knee flexion after total knee arthroplasty (TKA); however, no study has reported the impact of preoperative range of motion of the hip to the postoperative flexion angle of the knee thus far. METHODS: Of 38 consecutive patients who underwent posterior-stabilized TKA, we assessed 21 patients after excluding 17 patients who met exclusion criteria. The range of motion of the knee and the hip, age, body-mass index, serum albumin level, HbA1c, Kellgren-Lawrence grade, knee extension strength and radiological femorotibial angle as well as postoperative knee flexion angle at three months were evaluated. The preoperative data and the knee flexion angle at three months after TKA were compared using Spearman's rank correlation coefficient. RESULTS: Knee flexion angle at three months after TKA was positively correlated with preoperative flexion (ρ = 0.616, p = 0.007) and external rotation angle (ρ = 0.576, p = 0.012) of the hip as well as preoperative knee flexion angle (ρ = 0.797, p = 0.001). There were no correlations between postoperative knee flexion angle and other preoperative data. CONCLUSIONS: Patients with restricted flexion and/or external rotation of the hip may have contractures of Gluteus maximus, Gluteus medius and Tensor fasciae latae, which can cause hypertension of iliotibial tract. It may cause decreased internal rotation of the tibia when the knee is flexed, which affects postoperative knee flexion angle, thus limited flexion and/or external rotation of the hip might restrict knee flexion angle following TKA.

Corrigendum: Strain Assessment of Deep Fascia of the Thigh During Leg Movement: An in situ Study.

[This corrects the article DOI: 10.3389/fbioe.2020.00750.].

Ultrasound of iliotibial band syndrome.

Iliotibial band syndrome or friction syndrome is an overuse disorder of the lateral knee. It is commonly reported in athletes, such as runners and cyclists, and refers to pain related to physical activity. The diagnosis is based on clinical history and physical assessment. Imaging, including ultrasound, is mainly performed in recurrent or refractory cases. The purpose of this paper is to review the etiology, diagnosis, and therapy of iliotibial band syndrome with a focus on ultrasound imaging and ultrasound-guided treatment. Ultrasound findings include soft-tissue edematous swelling or discrete fluid collection, suggestive of bursitis, between the iliotibial band and the lateral femoral epicondyle. The thickening of the iliotibial band has been inconsistently reported. Treatment varies according to the disease phase and, in the acute phase, consists of rest, physical therapy, and anti-inflammatory medications. Ultrasound-guided local steroid injections are effective in relieving symptoms.

MRI visibility of the anterolateral ligament and the deep structures of the iliotibial tract.

PURPOSE: The visualization of potentially injured anatomical structures is crucial. Lately the anterolateral ligament (ALL) and the deep structures of the iliotibial tract (ITT) have been of increased clinical interest because of their role as important lateral stabilizers of the knee. The aim of this study was to assess the visibility of the ALL and the deep structures of the ITT using MRI. Good intra- and inter-observer reproducibility was hypothesized. METHODS: Knee MRI data from patients without ligamentous lesions were retrospectively analyzed by two radiologists at two time points using axial and coronal sequences. The visibility of the different parts of the ALL (femoral, meniscal and tibial part) and of the deep ITT, namely the deep attachments of the ITT to the distal femur and capsulo-osseous layer of the ITT, were determined on a binary (yes/no) basis. RESULTS: Seventy-one cases (42 men, 29 women) were studied. Inter-observer agreement was high. Cohen's kappa was 0.97 for the tibial part of the ALL and 0.76 for the femoral part. For the deep attachments of the ITT to the distal femur Cohen's kappa was 0.94. For each of the investigated parameters absolute agreement between the observers was at least 88%. Regarding intra-observer agreement Cohen's kappa was 0.62 for the femoral part of the ALL and 0.85 for the tibial part of the ALL. For the deep attachments of the ITT to the distal femur Cohen's kappa was 0.94. For each investigated parameter absolute agreement between the two time points was at least 83%. CONCLUSIONS: The presence of the anterolateral structures of the knee can be determined with substantial inter- and intra-observer agreement using MRI examination. This is applicable for both the ALL and the deep ITT. LEVEL OF EVIDENCE: Diagnostic study - Level III.

Autologous abdominal wall reconstruction using anterolateral thigh and iliotibial tract flap after extensive tumor resection: A case series study of 50 consecutive cases.

BACKGROUND: The utility of anterolateral thigh (ALT) + iliotibial tract (ITT) flaps for the reconstruction of large abdominal wall defects has been reported, especially in cases with huge skin defects, surgical contamination, or a history of radiotherapy. However, previous reports have mainly described short-term results such as flap success rates or incidence of wound complications. The present study reviewed 50 consecutive cases of abdominal wall reconstruction using an ALT+ITT flap after extensive tumor resection and evaluated the durability of this approach (incidence of bulge or hernia) and the factors affecting the results. PATIENTS AND METHODS: A detailed retrospective review of 50 consecutive cases was conducted. Computed tomography or magnetic resonance imaging findings were reviewed to assess the incidence of abdominal bulge or hernia. Items extracted as variables from patient records were subjected to univariate and multivariate logistic regression analyses to identify their relationship with postoperative abdominal bulge or hernia. RESULTS: Forty-six cases that were followed up for more than six months were analyzed. Twenty-three patients (50.0%) developed abdominal bulge, while none (0%) developed hernia. The multivariate logistic regression analysis revealed that old age and a high body mass index were independently associated with abdominal bulge, while abdominal defect size was not. CONCLUSIONS: Abdominal wall reconstruction using an ALT+ITT flap after extensive tumor resection was considered a reasonable option with a low risk of hernia despite a marked incidence of postoperative abdominal bulge; however, the usage of additional material may be considered depending on the situation.

Strain Assessment of Deep Fascia of the Thigh During Leg Movement: An in situ Study.

Fascia is a fibrous connective tissue present all over the body. At the lower limb level, the deep fascia that is overlying muscles of the outer thigh and sheathing them (fascia lata) is involved in various pathologies. However, the understanding and quantification of the mechanisms involved in these sheathing effects are still unclear. The aim of this study is to observe and quantify the strain field of the fascia lata, including the iliotibial tract (ITT), during a passive movement of the knee. Three fresh postmortem human subjects were studied. To measure hip and knee angles during knee flexion-extension, passive movements from 0° to around 120° were recorded with a motion analysis system and strain fields of the fascia were acquired using digital image correlation. Strains were computed for three areas of the fascia lata: anterior fascia, lateral fascia, and ITT. Mean principal strains showed different strain mechanisms depending on location on the fascia and knee angle. For anterior and lateral fascia, a tension mechanism was mainly observed with major strain greater than minor strain in absolute value. While for the ITT, two strain mechanisms were observed depending on knee movement: tension is observed when the knee is extended relatively to reference position of 47°, however, pure shear can be observed when the knee is flexed. In some cases, minor strain can also be higher than major strain in absolute value, suggesting high tissue compression probably due to microstructural fiber rearrangements. This in situ study is the first attempt to quantify the superficial strain field of fascia lata during passive leg movement. The study presents some limitations but provides a step in understanding strain mechanism of the fascia lata during passive knee movement.

Stiffness of the iliotibial band and associated muscles in runner's knee: Assessing the effects of physiotherapy through ultrasound shear wave elastography.

OBJECTIVES: To test the hypothesis that Iliotibial Band Syndrome (ITBS) is caused by excessive iliotibial band (ITB) tension, promoted by hip abductor and external rotator weakness, and evaluate the influence of 6 weeks of physiotherapy on ITB stiffness. DESIGN: Interventional study with control group. SETTING: Clinical. PARTICIPANTS: 14 recreational runners with ITBS and 14 healthy controls of both sexes. MAIN OUTCOME MEASURES: Ultrasound shear wave elastography, hip muscle strength, visual analog scale pain, subjective lower extremity function. RESULTS: No statistical differences in ITB tension between legs as well as between patients suffering from ITBS and healthy controls were detected. Results showed significant strength deficits in hip abduction, adduction as well as external and internal rotation. Following six weeks of physiotherapy, hip muscle strength (all directions but abduction), pain and lower extremity function were significantly improved. ITB stiffness, however, was found to be increased compared to baseline measurements. CONCLUSION: Shear wave elastography data suggest that ITB tension is not increased in the affected legs of runners with ITBS compared to the healthy leg or a physical active control group, respectively. Current approaches to the conservative management of ITBS appear ineffective in lowering ITB tone.

Histology and molecular pathology of iliotibial tract contracture in patients with gluteal muscle contracture.

The present study aimed to examine the pathologic changes of the iliotibial tract and discusses its relationship with gluteal muscle contracture. Samples of contractual iliotibial tracts were collected from six patients with contractures of the gluteal muscles and iliotibial tracts during their surgical treatment. Samples of normal iliotibial tracts were collected from six patients receiving surgeries for avascular necrosis of the femoral head who had no contractures of the gluteal muscles and iliotibial tracts. The tissue samples were stained using Hematoxylin and Eosin (H&E), Masson's trichrome, and Sirius Red. The mRNA and protein levels of various tissue repair genes were determined using quantitative real-time PCR and Western blotting. Both the normal and contractual iliotibial tracts consisted of type I and III collagens. The contractual iliotibial tracts had a significantly higher proportion of type III collagen in comparison with the normal iliotibial tracts. The mRNA expression levels and protein levels of tissue repair genes TGFß 1, bFGF, and matrix metalloproteinase-1 (MMP-1) in the contractual iliotibial tracts were up-regulated in comparison with that in the normal iliotibial tracts. However, the mRNA expression levels and protein levels of tissue inhibitors of metalloproteinase-1 (TIMP) in the contractual iliotibial tracts were down-regulated in comparison with that in the normal iliotibial tracts. The contractures of both the gluteal muscles and the iliotibial tracts share similar histology and molecular pathology. Our results indicate that iliotibial tract contracture is secondary to the gluteal muscle contracture and is a constant tissue repair process.

Anatomic Study and Reanalysis of the Nomenclature of the Anterolateral Complex of the Knee Focusing on the Distal Iliotibial Band: Identification and Description of the Condylar Strap.

BACKGROUND: The capsulo-osseous layer (COL), short lateral ligament, mid-third lateral capsular ligament, lateral capsular ligament, and anterolateral ligament (ALL) are terms that have been used interchangeably to describe what is probably the same structure. This has resulted in confusion regarding the anatomy and function of the anterolateral complex of the knee and its relation to the distal iliotibial band (ITB). PURPOSE: To characterize the macroscopic anatomy of the anterolateral complex of the knee, in particular the femoral condylar attachment of the distal ITB. We identified a specific and consistent anatomic structure that has not been accurately described previously; it connects the deep surface of the ITB to the condylar area and is distinct from the ALL, COL, and Kaplan fibers. STUDY DESIGN: Descriptive laboratory study. METHODS: Sixteen fresh-frozen human cadaveric knees were used to study the anterolateral complex of the knee. Standardized dissections were performed that included qualitative and quantitative assessments of the anatomy through both anterior (n = 5) and posterior (n = 11) approaches. RESULTS: The femoral condylar attachment of the distal ITB was not reliably identified by anterior dissection but was in all posterior dissections. A distinct anatomic structure, hereafter termed the "condylar strap" (CS), was identified between the femur and the lateral gastrocnemius on one side and the deep surface of the ITB on the other, in all posteriorly dissected specimens. The structure had a mean thickness of 0.88 mm, and its femoral insertion was located between the distal Kaplan fibers and the epicondyle. The proximal femoral attachment of the structure had a mean width of 15.82 mm, and the width of the distal insertion of the structure on the ITB was 13.27 mm. The mean length of the structure was 26.33 mm on its distal border and 21.88 mm on its proximal border. The qualitative evaluation of behavior in internal rotation revealed that this anatomic structure became tensioned and created a tenodesis effect on the ITB. CONCLUSION: There is a consistent structure that attaches to the deep ITB and the femoral epicondylar area. The orientation of fibers suggests that it may have a role in anterolateral knee stability. CLINICAL RELEVANCE: This new anatomic description may help surgeons to optimize technical aspects of lateral extra-articular procedures in cases of anterolateral knee laxity.

The anterolateral ligament and the deep structures of the iliotibial tract: MRI visibility in the paediatric patient.

PURPOSE: To assess the visibility of both the anterolateral ligament (ALL) and the deep structures of the iliotibial tract (ITT) by means of MRI in paediatric patients. To determine reproducibility for such measurements. METHODS: Knee MRI data from patients aged <18a without lesions of the capsule or ligaments, fractures, bone edemas, foreign material or motion artifacts were analyzed by two musculoskeletal radiologists separately and twice. The visibility of the different parts of the ALL was determined (femoral, meniscal, tibial parts). Similarly, the visibility of the different parts of the deep ITT was determined: deep attachments of the ITT to the distal femur (insertion near septum, supracondylar insertion and retrograde insertion) and capsulo-osseous layer of the ITT. RESULTS: We studied 61 cases (36 female, 25 male). Age was 15 years (±2.3). Interobserver agreement was high. Cohen's Kappa was 0.864 (95%CI: 0.715-1.000) for the tibial part of the ALL and 1.0 for the femoral part of the ALL. For the deep attachments of the ITT to the distal femur Kappa was 0.828 (95%CI: 0.685-0.971). Regarding intraobserver agreement, Cohen's Kappa was 1.0 for the femoral part of the ALL and 0.955 (95%CI: 0.867-1.000) for the tibial part of the ALL. For the deep attachments of the ITT to the distal femur Cohen's Kappa was 0.896 (95%CI: 0.782-1.000). CONCLUSION: On the basis of our findings it is concluded that the presence of the anterolateral structures of the knee can be determined by MRI in a pediatric population with substantial inter- and intraobserver agreement. This is true for both the ALL and the deep structures of the ITT. LEVEL OF EVIDENCE: Diagnostic study - Level 3.

Tensile properties of the human iliotibial tract depend on height and weight.

BACKGROUND AND AIMS: The human iliotibial tract (IT) is increasingly used in different types of musculoskeletal models. Previous findings indicate age-dependent changes of the human IT tensile properties, these lack confirmation to date. The relationship of the human IT and anthropometrical parameters, such as body height and weight has not been investigated before. MATERIALS AND METHODS: 33 fresh human IT samples (age range 4 months to 93 years) were uniaxially tested using digital imaging correlation and the latest advances in 3D-printing to standardize biomechanical soft tissues testing. RESULTS: The tensile parameters of the human IT are not age-dependent, except for the maximum strain in males. Height significantly correlated to elastic modulus, tensile strength and maximum strain of the human IT in males. Females just showed a significant correlation between maximum strain and weight, which was contrary to the findings in males. DISCUSSION AND CONCLUSION: Age-dependency of human IT tensile parameters could not be confirmed in the larger sample size investigated in this study. Due to the strong correlation with the tensile IT parameters in males, we suggest that height should be integrated when the IT is used in simulations, such as finite element analyses of the hip and knee.