Tibiofemoral joint ligaments + meniscus Flashcards
Capsular ligaments - Medial (tibial) Collateral Ligament (MCL)
- Medial epicondyle of femur to medial tibial condyle - strong, flat, 8-9cm long
- Has superficial fibres that blend anteriorly w/ the medial patellar retinaculum + deep fibres that attach to the medial meniscus
- Reinforces capsule medially
- limits knee extension + abduction (genu valgus). Best able to limit abduction in extended position when taut (e.g. standing)
- Superficial fibres of the MCL limit tibial external rot + anteromedial translation (preventing anteromedial rotatory instability of the knee)
Capsular ligaments – oblique and arcuate popliteal ligaments
Oblique popliteal ligament
- semimembranosus tendon expansion attaching to the central part of the posterior capsule, reinforcing the posterior capsule.
- limits knee extension
Arcuate popliteal ligament
- arches over the popliteus tendon from its attachment on the fibular head to reinforce the posterolateral capsule.
- limits knee extension
Extracapsular – Lateral Collateral Ligament (LCL)
- Lateral collateral ligament is extracapsular, rounded + about 5cm long
- Lateral to the joint capsule.
- Extends from lateral femoral epicondyle to lateral head of fibula (inserting w/ biceps femoris)
- Limits knee extension + adduction (genu varus)
Intra-capsular ligaments - Anterior Cruciate Ligament (ACL)
- anterior intercondylar area to lateral femoral condyle
- extra-synovial
- Limits primarily anterior translation of the tibia on the femur
- Depending on knee joint angle (i.e. knee is in flexion or extension), may also limit abduction (genu valgus) + rot of the tibia on femur (OKC)
- the combination of either varus or valgus forces with anterior translation of the tibia places greater strain on the ACL
- In CKC these activities may occur w/ excess inward/adduction movt during knee-loaded flexion
Intra-capsular ligaments - Posterior Cruciate Ligament (PCL)
- posterior intercondylar area to medial femoral condyle
- extra-synovial
- Limits primarily posterior translation of the tibia on the femur
- Limits adduction (genu varum) + rot of the tibia on femur, particularly b/w 90 + 120° of knee flexion
Ligaments limiting rotation
- OKC rot at the knee is limited by a combination of ligament constraints
- Limits to internal tibial rotation:
- Knee extended – PCL
- Knee flexed – superficial MCL
- Also: ACL, posteromedial capsule + ITB
- Limiting lateral tibial rotation:
- LCL
- PCL
Intra-capsular ligament – meniscofemoral ligament
- Intra-capsular ligament - a slip of the PCL passing from the back of the lateral meniscus to the medial femoral condyle
- helps to control the position of the lateral meniscus – how far forward the meniscus moves during knee extension + lateral rot
Tibiofemoral joint – primary and secondary restraints
- Knee ligs can be divided into primary + secondary restraints for each plane of movt
- Most restraining force occurs in primary restraints which limit joint motion + therefore protect secondary restraints
- Primary + secondary restraints are necessary for stability
- Muscle stabilisers are important secondary restraints at the knee
Knee movement with primary + secondary restraints
Anterior translation of the tibia
- Primary: ACL (86%), Secondary: capsule, ITB, MCL, LCL, medial meniscus
Posterior translation of the tibia
- Primary: PCL (94%), Secondary: capsule, popliteus, LCL
Knee abduction (genu valgus)
- Primary: MCL, Secondary: capsule, ACL, pes anserinus, medial gastro, semimem
Knee adduction (genu varus)
- Primary: LCL, Secondary: capsule, PCL, ITB, biceps femoris, lateral gastro
Medial rotation of tibia
- Primary: PCL (ext), Secondary: ACL, ITB, biceps femoris
Lateral rotation of tibia
- Primary: MCL, Secondary: popliteus, ACL, LCL
Tibiofemoral joint – lateral dynamic stability
- the popliteus muscle = important dynamic stability to lateral knee
- Additionally, ITB provides lateral support to the knee joint, thereby resisting adduction of the tibia on the femur
- In the flexed knee, the iliotibial band can assist in restricting excessive anterior translation of the tibia on the femur.
- During gait, biceps femoris + lateral gastro muscles also play a role in maintaining lateral knee joint stability
Tibiofemoral joint – medial dynamic stability
Pes Anserinus
- The pes anserinus (formed by the combination of the tendinous insertions of sartorius, gracilis + semiten) provides dynamic medial support to the knee joint, thereby actively resisting abduction of the tibia on the femur (knee valgus) + tibial external rot
Semimembranosus, medial head of gastrocnemius
- Semimem has an important dynamic stabilisation role in restraining external tibial rot + anteromedial translation, especially at higher flexion angles at the knee joint
- The proximal medial gastro also supports the posteromedial side of the knee
Tibiofemoral joint – line of gravity
- The line of gravity falls anterior to the knee joint, hence the weight of the body acts to keep the knee in an extended position
