L6 - Knee Flashcards
The nerves innervations the periarticular tissues in the knee joint are composed of what?
Both postganglionic autonomic sympathetic and sensory axons, the latter of which end peripherally as encapsulated or free sensory
Nerves to any one particular joint in the knee arise from what?
More than one level in the spinal cord
What are the two types of synovial fibers in the knee joint?
Postganglionic sympathetic adrenergic fibers and unmyelinated C fibers
Describe postganglionic sympathetic adrenergic fibers in the knee joint synovium
Located around blood vessels and are responsible for the control of articular blood flow
Describe unmyelinated C fibers in knee joint synovium
Responsible for pain transmission
Typically only fire when there is trauma and are therefore termed nociceptive
Prostaglandin E2 associated with inflammation can induce signaling in the nociceptive fibers causing pain in the normal range of movement
What are the cruciate ligaments?
Internal ligaments (within the capsule yet separate from the joint cavity)
Join femur to tibia
Named according to attachment to tibia: ACL and PCL
Describe attachments of the anterior cruciate ligament (ACL)
Anterior part of intercondylar area of tibia
Fibers orientated superiorly, posteriorly and laterally
Medial side of lateral condyle of femur
When is the ACL taut?
When the leg is extended
Prevents posterior displacement of the femur
Prevents anterior displacement of tibia
Describe the attachments of the PCL
Posterior part of intercondylar area of tibia
Fibers directed superiorly, anteriorly and medially
Lateral surface of medial condyle of femur
When is the PCL taut?
When the leg is flexed
Prevents anterior displacement of femur
Prevents posterior displacement of tibia
What are menisci?
C shaped plates of fibrocartilage on medial and lateral articular surfaces of tibia
Deepens articular surface and absorbs shock
What are the external margins of menisci?
Thick and attached to joint capsule (coronary ligaments)
What are the anterior edges of menisci?
Joined by transverse ligament of knee
Allows menisci to move together during movements of femur on tibia
Describe the medial meniscus
Broader posteriorly
Anterior horn may attach anteriorly to ACL
Posterior horn attaches anterior to PCL
Adherent to deep surface of tibial collateral ligament
Describe the lateral meniscus
Nearly circular; anterior and posterior ends closer together
Small and more mobile than medial meniscus
Posterior meniscofemoral ligament joins it to posterior cruciate ligament
Popliteus tendon passes between it and fibular collateral ligament
What is Osgood-Schlatter disease?
During activities that involve a lot of running, jumping and blinding a child’s thigh muscles (quads) pull on the tendon that connects the kneecap to the shinbone
The repeated stress can cause the tendon to pull away from the shinbone resulting in pain and swelling
The body may try to close that gap with new bone growth which can result in a bony bump at that spot
What is a groin pull?
The groin is the junction between the trunk and thigh
Strain, stretching and probably some tearing of the proximal attachments of thigh adductor/flexor muscles
What does Hilton’s law state?
That the same nerve trunks that supply motor branches to muscles crossing a joint likewise provide branches to the skin overlying insertions of the same muscles, and to the periarticular tissues of the joint proper
What is the anterior drawer sign?
Pulling of the knee and tibia forward will show an anterior displacement of the tibia showing a tear of the ACL
Can also test for PCL tear with posterior drawer sign
Describe meniscal tears
Commonly involves medial meniscus
Lateral meniscus usually does not tear because of mobility (may not be true)
Peripheral meniscal tears can often be repaired or will heal because of blood supply
Meniscal tears that do not heal or cannot be repaired are removed via arthroscopic surgery
What is an unhappy triad of injuries?
Occurs when the foot is fixed and twisting of the trunk occurs during a fall (ex. While playing football)
Tears the ACL, tibial collateral ligament and medial meniscus (of O’Donahue)
More recently it has been noted that the lateral meniscus is involved instead
