Lateral knee fascia
The iliotibial band is merely a lateral expansion of the fascia lata and made up of three layers: superficial, middle and deep.
Superficial and middle layer: encloses the tensor fascia lata anchoring it to the iliac crest. These layers unite at the distal end of the tensor fascia lata to form a tendon for the muscle. These two united layers receive fibers from the gluteus maximus and runs down the lateral thigh. As it courses down the lateral thigh Fairclough et al (2006) found the Iliotibial band continuous with the strong lateral intermuscular septum, which was firmly anchored to the linea aspera of the femur. Evans (1979) found fibers from the lateral intermuscular septum form the horizontal fibers of the iliotibial band.
Distally, after coursing through the Biceps Femoris and Vastus Lateralis Godin et al (2017) found the distal attachments of the Iliotibial band to be:
- 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 the 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 ITB (Kaplan fibers) connect the superficial ITB 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 ITB to the region of, or directly to, the lateral epicondyle as strong fibrous ‘tendonous’ strands and then more ‘ligamentous’ strands between the lateral epicondyle of the femur and Gerdy's tubercle on the tibia. Variable and indinstinct insertions from the capsulo-osseous layer are also attached to the lateral epicondyle.
- Capsulo-osseous layer: a distinct fascial portion of the deep Iliotibial band. Runs from just proximal to the lateral gastrocnemius tubercle to the lateral tibial tubercle*. Herbst et al (2017) found variable and indistinct attachments from this layer around the lateral femoral epicondyle. 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). Evans (1979) found additional attachments to the lateral meniscus.
- Gerdy 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 tubercle (Herbst et al 2017).
- Iliopatellar Band: attaches to the lateral aspect of the patella and patellar tendon. The distal edge of this portion forms the lateral patellotibial ligament, part of the lateral retinaculum.
*: lateral tibial tubercle is loacted on the anterolateral aspect of the proximal tibia, between the Gerdy tubercle and the fibular head (Godin et al 2017).
Herbst et al (2017) failed to the find the anterior lateral ligament on dissection. These authors found the capsulo-osseous layer of the ITB 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 tendonous fibrous bands of the Iliotibial band and the femur. There was just adipose tissue.
Wilke et al (2016) found more distally the Iliotibial band connected strongly to the crural fascia which in itself was hardly seperable 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 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 arises 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.
Additional muscular attachments to the Iliotibial band include:
· Vastus Lateralis (Becker et al 2010).
· Biceps Femoris.
· Tensor Fascia Lata.
· Gluteus Maximus.
Lateral patella retinaculum
The lateral patella retinaculum is made up of:
- Iliopatellar band of the ITB (ITB-P).
- Lateral patellofemoral ligament (LPFL).
- Lateral patellomeniscal ligament (LPML).
Fibers from the vastus lateralis form part of the lateral patella retinaculum (Waligora et al (2009).
Iliopatellar Band of ITB (ITB-P)
The ITB attaches to the lateral aspect of the patella and patellar tendon. The distal edge of this portion forms the ITB-P.
These fibres criss-cross in a predominantly transverse orientation. They are easily separated from the underlying joint capsule (Merican et al 2009).
These fibers are by far the strongest and stiffest structure in the lateral retinaculum. Being more transverse in orientation and densely arranged they resist medial displacement forces that pull the patella away from the ITB.
These fibers move anteriorly when the knee is extending knee slackening the ITB-P and is conversely pulled tight when the knee is flexed. Therefore these fibers are most tightly stretched in knee flexion and medial patella deviation.
Lateral patellofemoral ligament (LPFL) and lateral patellomeniscal ligament (LPML)
These capsulo-ligamentous bands are thickened bands of the lateral joint capsule. They are not always present as distinct fibre bands,
i. Lateral patellofemoral ligament (LPFL): patella (middle third) --> femur (distal and anterior to lateral epicondyle) (Shah et al 2017). The vastus intermedialis reinforces the LPFL (Waligora et al 2009).
ii. Lateral patellomeniscal ligament (LPML): lateral border of the patella --> anterior aspect of the lateral meniscus.
Medial knee fascia
Wymenga et al (2006) identified three layers of the fascia in the medial knee:
Layer I: superficial fascia
The superficial fascia is subcutaneous. It blends with the pes anserine and tibial periosteum distally, it covers the sartorius and quadriceps proximally, the retinaculum anteriorly, and forms the deep crural fascia posteriorly.
The superficial portion of layer I adheres to the sartorius. The deep portion of layer I adheres to the gracilis and semitendinosus tendons.
Layer II: superficial medial collateral ligament
The superficial medial collateral ligament extends from the femoral epicondyle to the anteromedial tibial crest 5–7 cm below the joint line. LaPrade (2009) found a majority of the distal attachments of the superficial medial collateral ligament to be to the semimembranosus and pes anserine bursa rather than the tibia.
Posteriorly these fibres are continuous with the oblique fibres of layer III although this was disputed by LaPrade (2009) who found no clear connection.
Anterior to the femoral attachment these fibres are continuous with the medial patellofemoral ligament.
Tuncay et al (2007) found the semitendinosus and gastrocnemius tendons to lie between layer I and II.
Just as the superficial portion of layer I adheres to the sartorius, the deep portion of layer I adheres to the gracilis and semitendinosus tendons. Tuncay et al (2007) found two fascial bands associated with the semitendinosus:
- Dense 3–4-cm band around the gracilis and semitendinosus tendons approximately 8–10 cm proximal to their tendon insertion.
- Fascial band originating from the semitendinosus and extending to the gastrocnemius fascia.
Layer III: the true capsular layer and mid-third medial capsular ligament (deep medial collateral ligament)
Layer III thickens and forms the deep medial collateral ligament as a thickening of the medial joint capsule.
The deep medial collateral ligament (layer III) separates the superficial medial collateral ligament (layer II) from the medial meniscus.
The deep medial collateral ligament extends from the medial femoral condyle to the meniscus and from the meniscus to the tibia.
Proximally the deep medial collateral ligament attachment merges into the superficial medial collateral ligament fibres, but sometimes it has a distinct attachment 0.5 cm distally.
The meniscotibial attachment of the deep medial collateral ligament is clearly separated from the superficial medial collateral ligament but blends with it posteriorly.
Anterior to the superficial medial collateral ligament layer III is thin and loose blending with layer I into the retinaculum.
Conjoint attachments of layers II and III
The conjoined tissue of layers II and III forms the posteromedial capsule
A condensation of fibres within the posteromedial capsule forms the posterior oblique ligament. This ligament is an important stabiliser of the medial side of the knee.
The femoral attachment of the posteromedial capsule is located at the adductor tubercle.
The posteromedial capsule is augmented by:
- Semimembranosus tendon: inserts into the posteromedial tibia just below the joint line. It has various extensions into the posteromedial capsule and the posterior capsule.
- Adductor Magnus tendon: LaPrade et al (2009) found the distal-medial aspect of the adductor magnus tendon had a thick fascial expansion, which fanned out posteromedially and attached to the medial gastrocnemius tendon, the capsular arm of the posterior oblique ligament and the posteromedial capsule.
- Gastrocnemius: as well as a thick fascial attachment to the adductor magnus the medial gastrocnemius has a thin fascial band extending to the capsular arm of the posterior oblique ligament (LaPrade et al 2009).
The medial retinaculum is made up of the:
- Medial patello-femoral ligament (MPFL).
- Medial quadriceps tendon–femoral ligament (MQTFL).
- Medial patello-tibial ligament (MPTL).
- Medial patello-meniscal ligament (MPML).
Medial patello-femoral ligament (MPFL)
The MPFL is an hourglass-shaped structure. Femur: adductor tubercle, medial femoral epicondyle and gastrocnemius tubercle --> patella: superomedial aspect (Aframian et al 2017). The patella attachments occur mainly through the aponeurosis of the vastus medialis and vastus intermedialis (Placella et al 2014).
Wymenga et al (2006) found attachments of the superficial medial collateral ligament (femoral epicondyle --> anteromedial tibial crest) to the MPFL. Waligora et al (2009) found the MPFL (as well as the LPFL) fused with the fibrous layer of the joint capsule.
These authors also found attachment of the posteromedial joint capsule to the MPFL attachment to the adductor tubercle.
Tanaka (2016) found variations in these attachment finding all MPFL fibers can either attach to the patella or quadriceps tendon.
Medial quadriceps tendon–femoral ligament (MQTFL)
Medial aspect of the distal quadriceps tendon --> femur: adductor tubercle region.
Medial patello-tibial ligament (MPTL)
Patella: medial to the inferior pole* --> tibia: anteromedial tibia (Kruckeberg et al 2019).
Medial patello-meniscal ligament (MPML)
Patella: medial to the inferior pole* --> medial meniscus (Hinckel et al 2019).
*: MPTL and MPML share a common insertion.
Mechanics of the medial patella ligaments
Tanaka et al (2019) found the MPFL accounts for only half of the total restraint to lateral patellar displacement.
These authors found the remaining contributions to patellar stability are derived from the combination of the MPTL and MPML, which function primarily in greater degrees of knee flexion.
In contrast Decante et al (2019) found during knee flexion, the upper bands (upper patella --> femur) stretched while the lower bands (lower patella --> femur) shortened.
Posterior knee fascia
Satoh et al (2016) found the popliteal fascia a single aponeurotic sheet acting as a three-layered retinaculum:
- Layer one. The superficial layer of the popliteal fascia. Strongly interwoven with the epimysium of biceps femoris along its lateral aspect and with that of the semimembranosus along its medial aspect. This ensures that the flexor muscles remained in their correct positions.
- Layer two. The intermediate layer: arose from the medial side of biceps femoris and merged medially with the superficial layer.
- Layer three. The deep layer: stretched transversely between the biceps femoris and the semimembranosus.
These authors found this fascia was innervated by the posterior femoral cutaneous or saphenous nerve. These nerves are closely related and distributed to densely packed collagen fibers in layer one (superficial layer) as free or encapsulated nerve endings. Therefore this fascia could be a source of pain in the upper region of the popliteal fossa.
Anterior knee fascia
Fascial layers of the anterior knee (Waligora et al 2009)
Fibrous layers that cover the knee anteriorly consist of:
- Superficial aponeurotic layer is a continuation of the fascia lata proximally and the crural fascia distally.
- Intermediate layer: is subdivided into the deep and superficial midline layers.
i. Superficial midline layer: laterally is a thick extension of the ITB. Medially is a thin expansion from the sartorius that connects to the fascia lata.
ii. Deep midline layer: fibers creating the quadriceps and patellar tendons and the crossed fibers of the vastus medialis and vastus lateralis traveling to the tibial condyles of the opposite side.
- Deep layer: fibrous layer. Medial and lateral to the patella. Comprises the patellofemoral and meniscopatellar ligaments.
Myofascial relations of the quadricep tendon (Waligora et al 2009)
Traditionally the quadriceps femoris insertion into the patella as a common tendon has been described as a three-layered arrangement:
- Superficial layer: rectus femoris.
- Middle layer: vastus lateralis (including vastus lateralis obliquus) and vastus medialis (including vastus medialis obliquus).
- Deep layer: vastus intermedialis.
The strict segregation of these layers can be misleading on dissection.
Superficial layer: rectus femoris
The rectus femoris inserts on to the anterior portion of the patella tendon. Some fibers continue on to the ligamentum patella.
The thickening of the deep fascia posterior to the rectus femoris contribute to the quadricep tendon.
Middle layer: vastus lateralis and vastus medialis
The vastus lateralis and vastus medialis unite to form a continuous aponeurosis that inserts onto the patella posterior to the rectus femoris and continues laterally and medially inserting into the sides of the patella.
Thickening of the fascia posterior to the vastus medialis and vastus lateralis contribute to the quadricep tendon.
Vastus lateralis (& vastus lateralis obliquus)
From the vastus lateralis fibers cross superficial to the patella to the medial condyle of the tibia.
Other fibers blends with the capsule of the knee and form part of the the lateral patellar retinaculum
The vastus lateralis obliquus is a distinct group of vastus lateralis fibers. They are separated from the main belly of the vastus lateralis. Much like the vastus medialis obliquus they can be classified as the more distal oblique fibers of the vastus lateralis.
This vastus lateralis obliquus can originate from the lateral intermuscular septum or ITB and attach on to the superolateral part of the quadriceps tendon.
These fibers provide a more direct lateral pull on the quadriceps tendon due to their lateral insertion on the quadriceps tendon.
Vastus medialis (& vastus medialis obliquus)
Most fibers of the vastus medialis end in an aponeurosis that blends with the medial side of the suprapatellar tendon or the rectus femoris tendon.
More distal fibers form a tendinous expansion attaching to the medial side of the patella. Deep fibers from this expansion reinforce the joint capsule as part of the medial patellar retinaculum.
Obliquely oriented fibers from the vastus medialis obliquus (with the vastus intermedialis) attach the MPFL to the patella (Placella et al 2014).
As with the vastus lateralis tendinous fibers from the vastus medialis obliquus pass across the patella to attach to the lateral tibial condyle.
Deep layer: vastus intermedialis
The vastus intermedialis inserts through a broad, thin tendon into the base of the patella.
Medially and laterally it reinforces the MPFL and LPFL.
Thickening of the deep fascia anterior to the vastus intermedialis contributes to the quadricep tendon.
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