Tensor Fascia Lata & Iliotibial Band: Anatomy & Function

Feb 3

Anatomy of the Iliotibial Band, Lateral Intermuscular Septum & Tensor Fascia Lata

Anatomy of the Iliotibial Band

The iliotibial band is merely a lateral expansion of the fascia lata. It is a consolidation of the tensor fascia latae anteriorly, gluteal aponeurotic fascia centrally, and gluteus maximus posteriorly. The proximal iliotibial band is divided into three layers: superficial, middle and deep.

Superficial and middle layer: encloses the tensor fascia lata anchoring it to the iliac crest. The superficial layer originates from the iliac crest anterior to the gluteal aponeurotic fascia origin, and the middle layer arises from the ilium just below the tensor fascia lata origin. These layers unite at the distal end of the tensor fascia lata to form a tendon for the muscle. This tensor fascia lata-iliotibial band junction is the only area of the iliotibial band to exhibit significant deformation on adduction stretch (Seemer et al 2020). These two united layers form the anterior iliotibial band which the tensor fascia lata inserts into and a posterior iliotibial band which the gluteus maximus and gluteal aponeurotic fascia (over the gluteus medius) attaches on to (Hutchinson et al 2022). Both tensor fascia lata and gluteus maximus have an epimysial relationship with the fascia lata by not only terminating on to the iliotibial band but by also how they originate from the fascia lata as well as their boney attachments (Fourie 2011).

As well as an anterior and posterior component the iliotibial band also has a superficial and deep layer separated by loose connective tissue. The superficial layer is the main tendinous component that runs vertically down from the iliac crest, being constituted by the superficial portion of the vastus lateralis and biceps femoris aponeurosis, extending down to the lateral patella retinaculum, fusing with the deep layer distal to the lateral epicondyle (Vieira et al 2007) and attaching to the tibia (Gerdy’s tubercle and lateral tibial tuberosity) (Terry & LaPrade 1996). From the linea aspera the deep fibers sweep back as the lateral intermuscular septum forming the horizontal fibers of the iliotibial band (Evans 1979). The deep layer descends to attach on to the lateral femoral epicondyle and from there fuses with the superficial layer. These two fused layers travels to the patella and inserts widely at and around Gerdy’s tubercle (Vieira et al 2007). A deeper layer to this deep layer exists as the capsuloosseous layer of the iliotibial band (Terry & LaPrade 1996) (refer below).

Distally, after coursing through the biceps femoris and vastus lateralis the distal attachments of the iliotibial band are (Godin et al 2017):

Proximal bundle: runs nearly transversely from the superficial iliotibial band to the distal femur. Inserts on the proximal ridge of the distal femoral body, distal to the lateral intermuscular septum 53.6 mm proximal to the lateral epicondyle.
Distal bundle: runs from the superficial iliotibial band from a proximal and lateral to distal and medial direction inserting on to the supracondylar flare. This could be Kaplan fibers mentioned below under 'lateral femoral condyle and epicondyle'.
Lateral femoral condyle and epicondyle: Herbst et al (2017) found transverse fibers from the deep layer of the iliotibial band (Kaplan fibers) connect the superficial iliotibial band to the distal femoral metaphysis and condyle. These authors also found accessory insertions of the deep iliotibial band located proximal and anterior to the lateral femoral epicondyle. Fairclough et al (2006) described the attachment of the iliotibial band to the region of, or directly to, the lateral epicondyle as strong fibrous ‘tendinous’ strands and then more ‘ligamentous’ strands between the lateral epicondyle of the femur and Gerdy's tubercle on the tibia. Variable and indistinct insertions from the capsulo-osseous layer are also attached to the lateral epicondyle. These Kaplan fibers hold the iliotibial band against the lateral epicondyle, allowing the distal iliotibial band to function like a ligament by resisting anterior translation (by pulling the lateral tibial plateau posteriorly) and internal rotation of the tibia (Ayati Firoozabadi et al 2023) from >30 degrees knee flexion (Yamamoto et al 2006).
Capsulo-osseous layer: a distinct fascial portion of the deep iliotibial band. Runs from the lateral femoral epicondyle (Herbst et al 2017), just proximal to the lateral gastrocnemius tubercle and supracondylar ridge (Vieira et al 2007) to the lateral tibial tubercle* and Gerdy’s tubercle. The attachments to the lateral femoral epicondyle are associated with the lateral patellofemoral ligament which extends from the lateral femoral epicondyle to the lateral patella (Vieira et al 2007) and is described as a thickening of the lateral knee joint capsule (Merican & Amis 2008) and may parallel Evans (1979) iliotibial band attachments to the lateral meniscus. The capsulo-osseous layer is intimately related to the lateral knee capsule and the fascia surrounding the lateral gastrocnemius tendon and biceps femoris (Herbst et al 2017) as the posterior boarder of the capsulo-osseous layer is the posterior edge of the biceps femoris (Vieira et al 2007).
Gerdy’s tubercle: the superficial iliotibial band attaches on to a wide area from Gerdy tubercle anteriorly to the anterolateral and lateral tibia posteriorly. Deep fibers of the iliotibial band attach slightly posterior to Gerdy’s tubercle (Herbst et al 2017).
Iliopatellar band: the superficial layer of the iliotibial band attaches to the lateral aspect of the patella and patellar tendon through the lateral retiniaculum (superficial oblique retinaculum and the lateral femoropatellar ligament) (Vieira et al 2007). The distal edge of the iliopatellar band forms the lateral patellotibial ligament, part of the lateral retinaculum formed from the quadriceps aponeurosis that fuses with the joint capsule (Merican & Amis 2008). Merican et al (2009) found these fibers resist knee flexion and medial patella deviation.
Ligamentum patella: extends from the lateral boarder of the patella to the superolateral boarder of the lateral tibial plateau (Vieira et al 2007).

*: The lateral tibial tubercle is located on the anterolateral aspect of the proximal tibia, between the Gerdy’s tubercle and the fibular head (Godin et al 2017) It serves as a conjoint attachment point for the merger of the superficial and deep layers of the iliotibial band, as well as the deeper cpasulo-osseous layer (Terry & LaPrade 1996)..

Herbst et al (2017) failed to the find the anterior lateral ligament on dissection. These authors found the capsulo-osseous layer of the iliotibial band and the mid-third capsular ligament both occupied anatomic locations that are similar to that of the anterior lateral ligament. This ligament is documented as resisting internal rotation of the tibia.

Fairclough et al (2006) found conversely to popular belief no bursa was found between the tendinous fibrous bands of the iliotibial band and femur just adipose tissue. However, tissues between between the distal iliotibial band and lateral femoral epicondyle, comprising adipose tissue or a bursa, can undergo lateral compression by the iliotibial band as tension is increased in the posterior fibres as the knee is flexed past 30 degs (Hutchinson et al 2022). This tightness of the iliotibial band causing an excessive lateral compression of the underlying of the underlying tissues could explain the reduced hip adduction range of motion in iliotibial band syndrome patients (Seemer et al 2020).

This in contrast to the previous theory of iliotibial band syndrome that stated the distal iliotibial band went from anterior to the lateral femoral epicondyle in full knee extension, to posterior to the lateral femoral epicondyle in knee flexion beyond 30 degs. This ‘to and fro’ movement of the lateral femoral epicondyle was thought to cause a constant frictioning of the underlying tissues. This ‘movement’ of the iliotibial band was found to be an illusion created by the shifting of tension from the anterior fibers in knee extension to the posterior fibres of the iliotibial band beyond 30 degs flexion, with actual movement of the iliotibial band being negated by the fact it is tethered to the distal femur, except for the upper portion of the lateral femoral condyle (Hutchinson et al 2022). During knee flexion, when the iliotibial band is placed under tension, its fascial consistency prevents it from lengthening (Wu et al 2023) and the bands of fascia lata, that are contiguous with the iliotibial band, and attaches on to the patella, come under tension (Fairclough et al 2006). This tension in flexion, from the iliotibial band, causes its contiguous fascia lata to slide backwards pulling the patella laterally and the vastus medialis to medially counter this lateral patella movement (Wu et al 2023). At the same time flexion tenses the ligamentous part of the iliotibial band pulling the lateral tibial plateaus posteriorly into external rotation (Fairclough et al 2006) which resists anterior translation and internal rotation of the tibia (Ayati Firoozabadi et al 2023) from >30 degrees knee flexion (Yamamoto et al 2006) as Kaplan fibers hold the iliotibial band against the lateral femoral epicondyle (Ayati Firoozabadi et al 2023).

Wilke et al (2016) found more distally the iliotibial band connected strongly to the crural fascia which in itself was hardly separable from the peroneal longus fascia.

Deep layer: The deep layer of the iliotibial band emerges where the superficial and middle layers fuse distal to the tensor fascia lata (Putzer et al 2017). From here it runs superiorly coursing deep attaching to the vastus lateralis and rectus femoris fascia. Coursing deeper still it follows the iliofemoral ligament to attach to the supraacetabular fossa between the tendon of the reflected head of the rectus femoris and the hip joint capsule. It resists hip extension.

Williams (1879) gives a description of the attachment of the deep layer of the iliotibial band to the rectus femoris. He describes at a short distance below the insertion of the tensor fascia lata into the deep layer of the iliotibial band a strong process of fascia lata arising from the iliotibial band passing obliquely upwards and inwards to join the tendon of the rectus femoris at the junction of its two heads. It also spreads backwards over the outer surface enclosing the reflected head of the rectus femoris, to which it is very firmly adherent, being fixed above to the inferior gluteal line, anterior inferior iliac spine and below blending with the capsule of the joint. This band of fascia binds down the tendon of the reflected head of the rectus femoris and connects the two heads.

These strong anatomical connections with the rectus femoris could explain the association of patellofemoral syndrome and tightness of rectus femoris, iliotibial band and gastrocnemius. Although there is no association found between patellofemoral syndrome and tightness in the hamstring and quadratus lumborum muscle tightness (Sannasi et al 2023).

Anatomy of the Lateral Intermuscular Septum

The iliotibial adheres firmly to the linea aspera via its attachments to the entire length of the lateral intermuscular septum. The lateral intermuscular septum separates the anterior and posterior compartments of the thigh as it originates from the insertion of the gluteus maximus before extending distally between the vastus lateralis and biceps femoris to terminate at the lateral femoral condyle. The lateral intermuscular septum receives fibers (i) anteriorly from the vastus lateralis. Although the vastus lateralis has a loose relationship with the fascia lata as it can be easily dissected from the muscle, it has a close relationship with the entire length of the lateral intermuscular septum as fascial septa from the intermuscular septum pass between the muscle’s fascicles forming an epimysial relationship (Fourie et al 2011); (ii) anterior lower part from the vastus intermedius; (iii) the posterior and proximal one quarter from the gluteus maximus; (iv) the posterior and distal three quarters from the short head of biceps femoris (Seeber et al 2020).

The muscles attaching on to, and tightening the fascia lata pulls the individual muscle groups closer together within their intermuscular septa (Sarda et al 2019).Whilst the lateral intermuscular septum technically resists hip adduction it is to a degree that it is not statistically significant as (i) the lateral intermuscular septum, via the iliotibial band and tensor fascia lata, doesn’t directly cross the hip joint; (ii) during hip adduction forces are dissipated through the pathway of least resistance with most tissue elongation, in the iliotibial band complex, occurring at the tensor fascia lata-iliotibial band junction, not the deeper iliotibial band fibers that attaches to the linea aspera via the lateral intermuscular septum; (iii) hip adduction is primarily limited by the superior portion of the hip capsule as well as gluteus medius and minimus rather than the iliotibial band. After transection of the iliotibial band hip adduction only increases between 0.70-0.72 degs (Seeber et al 2020).

Anatomy of the tensor fascia lata

The tensor fascia lata arises from the anterior part of the outer lip of the iliac crest; from the outer surface of the anterior superior iliac spine, and part of the outer boarder of the notch below it, between the gluteus medius and sartorius; and from the deep surface of the fascia lata.

It is inserted between the two layers of the iliotibial band at about the junction of the middle and upper third of the thigh.

Adaptions of the Iliotibial band and its muscles to a biped posture

Gluteus maximus adaptations to a biped posture

The gluteus maximus in humans is much larger in size when compared to non-human primates as it stabilises the trunk which, in turn, spurred on bipediality in humans (Hutchinson et al 2022). Indeed, the superior portion of the gluteus maximus which is thicker in man than in any other primates (Stern 1972), and comprises 40–70% of the muscles total mass, has a unique insertion by way of a thick laminar tendon on to the iliotibial band which allows it transmit large forces as it acts as a hip abductor (Hutchinson et al 2022) and potentially allows it to stabilise the knee in extension. Other authors found, due to the angulation of the sacrum in upright humans (Lieberman et al 2006), and attachment of the gluteus maximus to the sacrotuberous ligament (Shiraishi et al 2018), there is increased leverage of the gluteus maximus during hip extension, whereas in apes the gluteus maximus only extends the thigh at the hip to prevent it from flexing. This allows these superior fibers of the gluteus maximus to (i) extend and stabilise the hip and sacroiliac joint e.g when going from a sitting or squat position to standing; (ii) along with the erector spinae control flexion of the trunk relative to the stance leg during standing and running>walking; (iii) whilst running engage during the middle or end of swing phase functioning in swing-limb deceleration, and, during foot-strike to stabilise the pelvis (Lieberman et al 2006).

The superficial fibers of the inferior gluteus maximus also attach on to the iliotibial band (Flato et al 2017). In contrast, the other fibers of the inferior gluteus maximus which attach on to the femur at the gluteal tuberosity (Buckthorpe et al 2019) and, by an evolutionary ‘modified’ ascending tendon to the linea aspera, transmits less force than the superior portion of the gluteus maximus that inserts into the iliotibial band, and functions as a hip extensor and external rotator (Hutchinson et al 2022).

Fetal development of the gluteus maximus, tensor fascia lata and iliotibial band

With 60% of the gluteus maximus and tensor fascia lata attaching on to the iliotibial band it is substantially stretched by the action of these muscles. This enables the iliotibial band to store elastic energy that is recovered at different phases of the gait to optimise locomotor efficiency when both propelling movement and providing lateral stability. Due to adaptations to biped posture the insertion of the superior portion of the gluteus maximus to the iliotibial band has lead to the development of a far more pronounced iliotibial band than what exists in other primates. But humans are not born with a distinct iliotibial band, the characteristic adult iliotibial band that attaches to Gerdy’s tubercle is formed later after we begin to walk (Hutchinson et al 2022).

The iliotibial band is formed from two extensions of the gluteal fascia: (i) from a laterally and distally extending connecting band located between the superior and inferior gluteus maximus (Shiraishi et al 2018) that potentially forms the posterior aspect iliotibial band; (ii) an anteriorly extending gluteal fascia that passes anteriorly over the tensor fascia lata to attach onto the vastus lateralis fascia that extends down the thigh (Cho et al 2018) potentially forming the anterior aspect of the iliotibial band. The posterior and anterior specialisations of the iliotibial band are seen in adults where the posterior iliotibial band stores about 6 J per stride during the late swing phase at fast running speeds (when the gluteus maximus stretches and elongates the iliotibial band by 4%) and the anterior iliotibial band stores about 1 J of energy per stride during the late stance (when the tensor fascia lata stretches and elongates the iliotibial band by 2%) and early swing phases (Eng et al 2015).

Connecting band between the superior and inferior gluteus maximus

One part of the iliotibial band is formed from the gluteus maximus as it originates as a ‘intermediate tendon’ between the two separated portions of the gluteus maximus. These separated portions, with different attachment sites, are the superior (major) portion of the gluteus maximus and the inferior portion of the gluteus maximus. The inferior portion of the gluteus maximus is attached to the biceps femoris and develops more latterly than the superior portion. The intermediate tendon connecting the superior and inferior gluteus maximus extends laterally and distally to pass over the greater trochanter, but the thickest part of this tendon is not attached to the greater trochanter but is located more distally. As this intermediate tendon becomes longer and wider its fibers extend so they run in a different plane from those of the superior and inferior gluteus maximus muscles making it a distinct ‘connecting band’ in its own right that extends laterally and distally (down the leg). This makes it distinct from, from example, the intermediate tendon of the omohyoid that results from a change from a single band-like muscle, in contrast, the connecting band happens to find itself at a random meeting point between the superior and inferior gluteus maximus muscles which at this stage are two different muscles of separate origins (Shiraishi et al 2018).

The connecting band primarily gets pushed out and down by the laterally-developing greater trochanter and secondarily gets pulled down by the descent of the inferior gluteus maximus from the distal growth of the attached biceps femoris, and, growth of the femur. The inferior gluteus maximus loses its attachment to the biceps femoris and/or muscles around the coccyx as it requires a new strong origin from the sacrotuberous ligament to support its role in extending the hip in order to provide an upwards strong traction on the iliotibial band (Shiraishi et al 2018). This connecting band, however, is too short to reach the tibia and disperses into the subcutaneous tissue (Cho et al 2018) so could it represent the attachment of the superior gluteus maximus to the posterior iliotibial band and the longer extended vastus lateralis fascia a canditate for the adult iliotibial band?

Gluteal fascia extension —> over the tensor fascia lata —> vastus lateralis fascia

The tensor fasciae lata doesn’t directly contribute to the early development of the iliotibial band as it develops later than formation of the iliotibial band from the gluteus maximus (Shiraishi et al 2018). The posterior fibers of the tensor fascia lata develops from the gluteus fascia over the inferior-anteromedial end of the gluteus maximus and medius with there being no clear demaraction between the gluteus medius and tensor fascia lata (= posterior fibers abduct and internally rotate the hip) and the anterior fibers of the tensor fascia lata develop from the iliacus (= anterior fibers flex the hip). The tensor fascia lata attaches (i) to the lateral side of the iliacus, being just lateral to the origin of the rectus femoris; (ii) infero-antero-medial gluteus maximus and gluteus medius. As functional differentiation develops between the gluteus medius and maximus the tensor fascia lata tightly connects with the gluteus maximus fascia, refer below; (iii) inferiorly the tensor fascia lata extends distally along the lateral surface of the vastus lateralis muscle inserting on to the overlying vastus lateralis fascia (Cho et al 2018).

This vastus lateralis fascia, as a distinct fascial plane in its own right, forms before the fascia lata of the thigh. It appraoches the femur as at the fetal posterior intermuscular septum (between the vastus lateralis-biceps femoris) and terminates at the patella and lateral quadriceps tendon. The first layer of the fascia lata originates from the surface of the vastus muscles, but as the next fascial layer develops it strips away the first fascial layer from the muscle so there is now a new inner layer attached to the muscle and an old outer layer that was once attached to the muscle. As the vastus lateralis fascia, that forms the ‘thigh portion’ of the future iliotibial band, is formed before the fascia lata, subsequent layers of fascia lata, that forms around the whole thigh, push the iliotibial band to the outside. As the third or fourth layer of the fascia lata is added after birth the initial patellar attachment of the iliotibial band is loosened so it can descend to attach on to the tibia. This separation of the vastus lateralis fascia, that goes on to form the ‘thigh portion’ of the iliotibial band, from the vastus lateralis muscle by subsequent layers of fascia lata allows the iliotibial band to function independently from the quadricep tendon (Cho et al 2018).

Just as the vastus lateralis fascia forms the ‘thigh portion’ of the iliotibial band the gluteal fascia forms the lateral ‘pelvic portion’ of the iliotibial band. However, the gluteal fascia and vastus lateralis fascia have to join to form a unified band. The gluteus maximus fascia passes anteriorly towards the tensor fascia lata and then divides into two laminae sandwiching the tensor fascia lata. In doing so the tensor fascia lata acts as a bridge connecting the gluteus maximus fascia and the vastus lateralis fascia (Cho et al 2018). As seen in patients with hip flexion deformity, and in the superior gluteus maximus of quadrupedal mammals that is smaller than that of humans and s a more anterior insertion fuses with the smaller tensor fascia lata (Eng et al 2015) functioning as a hip flexor and abductor, hip extension, as function a function of the human gluteus maximus, is essential for an upright posture. Therefore, the space the tensor fascia lata provides between the gluteal and vastus fascia enables the gluteus maximus to have a more posterior attachment to function as a hip extensor and provide the strong upward traction on the iliotibial band (Cho et al 2018) needed to stretch the iliotibial band for an upright posture (Eng et al 2015).

The splitting of the gluteus maximus fascia to sandwich the tensor fascia lata, that forms the future iliotibial band, represents a morphology similar to that of the adult iliotibial band that splits to embed the tensor fascia lata (refer ‘Anatomy of the Iliotibial Band, Lateral Intermuscular Septum & Tensor Fascia Lata; Anatomy of the Iliotibial Band’) (Cho et al 2018). Therefore, could this represent the attachment of the tensor fascia lata and gluteal aponeurosis to the iliotibial band?

Movement of the Iliotibial Band

The iliotibial band functions as a strut during walking storing considerable magnitudes of elastic energy, acting as both a trunk, hip and knee lateral stabiliser. The iliotibial band stores up to 5% of the total positive work during a moderately paced run, which is just 14% of that which the achilles does (Hutchinson et al 2022). However, this tension isn’t stored uniformly, the posterior iliotibial band, which receives attachments from the superior fibers of the gluteus maximus and superficial fibers of the inferior gluteus maximus, and also, the gluteal aponeurosis (that covers the anterior two thirds of the gluteus medius) (Flato et al 2017) transmits larger forces, and thus has a larger capacity for energy absorption, than what the anterior iliotibial band does which the tensor fascia lata inserts into (Hutchinson et al 2022).

The superficial and deep layers of the iliotibial band (refer ‘Anatomy of the Iliotibial Band’) not only move separately, but also in opposite directions. This independent movement of the superficial and deep layers of the iliotibial band is determined by the thickness of the loose connective tissue between them. A reduced thickness of this loose connective tissue relates to an absence of motion in the deep layer of the iliotibial band. Variations in hyaluronan content and number of elastic fibres resulting in a densification of the loose connective tissue and its extracellular matrix are also likely associated with a reduction of fascial sliding between the layers of the iliotibial band (Besomi et al 2022).

The iliotibial band, as it is substantially stretched by the tensor fascia lata and gluteus maximus, stores forces in the form of elastic energy that is recovered at different phases of gait to optimise locomotor efficiency when both propelling movement and providing lateral stability. However, different areas of the iliotibial band have different levels of give depending on (i) the direction of applied force, with it being stiffer in a longitudinal direction of applied force (e.g. flexion/extension and adduction/abduction) and more compliant in a transverse direction; (ii) the level of the iliotibial band with it being most stiff and least pliable in a longitudinal direction distally at the superior boarder of the patella, most pliable as it passes over the distal end of the belly of the vastus lateralis and then slightly stiffens back up again proximally at the attachment of the gluteus maximus and tensor fascia lata to the iliotibial band. The iliotibial band is thicker distally and thins out more proximally. This increased thickness and reduced pliability at the distal end of the iliotibial band as it passes over the knee may reflect the considerable mechanical stress on the iliotibial band during knee movement, just as whilst the iliotibial band is thinner proximally the constant pulling from the gluteus maximus and tensor fascia lata on the iliotibial band may cause it to stiffen back up a bit. The increase pliability of the iliotibial band over the proximal end of the vastus lateralis may allow it to function in absorbing and dispersing mechanical stress as the vastus lateralis exerts greater force compared to the other quadricep muscles (Otsuka et al 2020) and the fascia lata covering the vastus lateralis is fairly loose allowing it to reduce the dissipation of forces created by epimuscular force transmission (Fourie et al 2011); (iii) stiffest in the longitudinal direction at 0 deg hip extension/90 degs knee flexion and slackest at 90 degs hip flexion/0 deg knee extension. As hip angle effects iliotibial band stiffness more than that of the knee angle the iliotibial band can be stretched more easily by hip extension than knee flexion (Otsuka et al 2020).

In hip adduction both superficial and deep layers of the iliotibial band move proximally. With contralateral sidebending the superficial layer of the iliotibial band moves proximally, this is more so not when not when the trunk does a straight bend as to move relative to the pelvis, but when the trunk bends as to move away from a vertical plum (gravity) line (Besomi et al 2022).

Due to the attachments of the gluteus medius to the posterior iliotibial band increased activity of the gluteus medius largely results in proximal motion of the superficial layer of the iliotibial band. Due to adherence of the deep layer of the iliotibial band to the underlying tissues, contraction of the gluteus medius, can, in some people, result in a proximal displacement of this deep layer (Besomi et al 2022).

Contraction of the tensor fascia lata can result in both superficial and deep iliotibial layers moving either proximally or distally (Besomi et al 2022). This maybe due to the tensor fascia lata role in pulling anterosuperiorly on the iliotibial band to flex the hip (Hutchinson et al 2022). It is this mobile tensor fascia lata-iliotibial band junction that is the only area of the iliotibial band to exhibit significant deformation on adduction stretch. The rest of the iliotibial band is more resistant to stretch due to its form attachment to the linea aspera by the lateral intermuscular septum (Seeber et al 2020).

Due to the oblique insertion of the gluteus maximus into the iliotibial band, in contrast to the longitudinal insertion of gluteus medius and tensor fascia lata, contraction of the gluteus maximus is unrelated to a specific direction of fascial displacement (Besomi et al 2022). Therefore, the superior fibers of the gluteus maximus, that functions as a hip abductor (Hutchinson et al 2022) and the superficial fibers of the inferior gluteus maximus that insert into the posterior iliotibial band, may not be able to have the same effect on fascial gliding in the ilitiobial band as the tensor fascia lata due to the oblique orientation of its applied force (Besomi et al 2022). However, there is a greater stored energy from larger forces generated from the gluteus maximus in the posterior fibers of the iliotibial band than what there is in the anterior portion of the iliotibial band from the tensor fascia lata (Hutchinson et al 2022).

It is this shifting of tension from the anterior fibres of the iliotibial band in knee extension to the posterior fibres beyond 30 degs flexion, that is thought to account for the ‘illusionary movement’ of the distal iliotibial band. Previously, the iliotibial band was though to move from anterior to the lateral femoral epicondyle in full knee extension, to posterior to the lateral femoral epicondyle in knee flexion beyond 30 degs. Due to the tethering of the iliotibial band to the distal femur (except for the upper portion of the lateral femoral condyle), this movement was found to be an impossibility the fascia lata, that is contigous with the iliotibial band, and attaches on to the patella does exhibit some movement. During knee flexion, when the iliotibial band is placed under tension, its fascial consistency prevents it from lengthening (Wu et al 2023) and the bands of fascia lata, that are contiguous with the iliotibial band, and attaches on to the patella, to come under tension (Fairclough et al 2006) pulling the patella laterally which is countered by a medial pull from the vastus medialis (Wu et al 2023) At the same time flexion tenses the ligamentous part of the iliotibial band pulling the lateral tibial plateaus posteriorly into external rotation (Fairclough et al 2006) which resists anterior translation and internal rotation of the tibia (Ayati Firoozabadi et al 2023) from >30 degrees knee flexion (Yamamoto et al 2006) as Kaplan fibers hold the iliotibial band against the lateral femoral epicondyle (Ayati Firoozabadi et al 2023).

Actions of the tensor fascia lata

Traditionally the tensor fascia lata along with the more vertical anterior and middle fibers of the gluteus medius are involved in hip abduction holding the pelvis horizontal during the stance phase of the gait:

Heel strike: anterior fibers of the gluteus medius initiates initial abduction during the heel strike keeping the pelvis horizontal (Gottschalk et al 1989). The gluteal aponeurosis, that arises from the posterior iliac crest and extends distally, covering the anterior two thirds of the gluteus medius, and inserts into the posterior iliotibial tract (and onto the gluteal tuberosity) (Flato et al 2017) may also help laterally stabilise the pelvis The superior fibers of the gluteus maximus, that attach on to the iliotibial band and have a hip abductor function, may contribute to lateral stability at this phase, just as the inferior fibers of the gluteus maximus, the superficial fibers of which attach on to the iliotibial band, and deep fibers attach on to the femur, contribute to hip extension (Hutchinson et al 2022).

Mid-stance: tensor fascia lata keeps the pelvis horizontal. Anterior rotation of the pelvis is achieved from the anterior fibers of the gluteus medius (Gottschalk et al 1989).

The hip joint is stabilised with the posterior fibers of the gluteus medius from heel strike to mid-stance and from the gluteus minimus from mid-stance to back stride (Gottschalk et al 1989).

The other actions of the tensor fascia lata include (i) very weak internal rotation and knee extension (Umehara et al 2015), with the posterolateral fibres functioning in internal rotation (and hip abduction) (Cho et al 2018) and (ii) via the anteromedial fibers, hip flexion (Cho et al 2018).

Stretching the Iliotibial band

Fredericson et al (2002) found a hip adduction stretch with the subjects arms reaching over head (i.e full shoulder abduction and extension) increased the stretch on the iliotibial band. Wilhelm et al (2017) found that a similar stretch to this (without using the added leverage of the shoulder position) didn’t uniformly increase the stretch throughout the iliotibial band but did so most prominently in the proximal portion.

Evans (1979) found the deep layer of the iliotibial band resisted hip extension.

As the hip is extended tension shifts in the iliotibial band from the anterior to posterior fibers meaning that different regions of the band are tensioned depending on the movement pattern (Hutchinson et al 2022). Kaplan and Emanuel (1958) suggested the tensor fascia lata pulls the iliotibial band anteriorly in hip flexion and the gluteus maximus pulls the iliotibial band posteriorly in hip extension and it was the attachment of the iliotibial band to the lateral intermuscular septum that restricts this anteroposterior movement. The action of the gluteus maximus on the iliotibial band was confirmed by Chen et al (2006) who found in individuals with gluteus maximus contracture the inferiorly-laterally orientated fasciculi of the gluteus maximus causes a medial-posterior displacement of the iliotibial band behind the greater trochanter.

As the knee moves into flexion the capsulo-osseous layer of the iliotibial band comes under tension as its insertion on the distal femur and proximal tibia significantly separates from 60degs to 105degs with maximal changes occurring at 105degs (Burkhart et al 2020). With progressively flexion shifting tension from the anterior to the posterior fibers of the iliotibial band (Fairclough et al 2006). These changes during flexion are significantly larger in the anterior compared to the posterior boarder with a significant increase in the length of the anterior capsulo-osseous layer at more than 15degs flexion and on the posterior fibers at angles greater than 75degs (Burkhart et al 2020), which possibly is due to the attachments of the biceps femoris. This tension on the iliotibial band during tenses the bands of fascia lata, that are contiguous with the iliotibial band, and attaches on to the patella, (Fairclough et al 2006) pulling the patella laterally which is countered by a medial pull from the vastus medialis (Wu et al 2023).

At the same time flexion tenses the ligamentous part of the iliotibial band pulling the lateral tibial plateaus posteriorly into external rotation (Fairclough et al 2006) which resists anterior translation and internal rotation of the tibia (Ayati Firoozabadi et al 2023) from >30 degrees knee flexion (Yamamoto et al 2006) as Kaplan fibers hold the iliotibial band against the lateral femoral epicondyle (Ayati Firoozabadi et al 2023). Kittl et al (2016) reported that the distal iliotibial band is the primary restraint to internal rotation between 30 and 90 of knee flexion. Herbst et al (2017) concurred with these findings determining the iliotibial band is under greatest stretch resisting internal tibial rotation at 60 degs knee flexion. Beyond 30 degs knee flexion, as tension increases in the posterior fibers of the iliotibial band the band compresses medially against the lateral femoral epicondyle (Hutchinson et al 2022).

Stretching of the tensor fascia lata

Anterior fibers of the tensor fascia lata (that originate from the iliacus) flex and abduct the hip, whilst the posterior fibers (that originate from the gluteus medius) abduct and internally rotate the hip (Sarda et al 2019). Therefore, traditionally the tensor fascia lata has been stretched using hip adduction/extension/external rotation.

Umehara et al (2015) found that hip adduction/extension with added knee flexion at >90 degs stretched the tensor fascia lata more than adding hip external rotation. This is because the tensor fascia lata is very minimally, if not at all, used as an internal rotator of the hip.

This may explain why using knee flexion reduced the range of motion in hip adduction when performing Ober’s test (Gajdosik 2003)

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Darren Winter https://www.ducodigital.com