human structure and movement: knees

Tensor fascia latae

spans the knee laterally, helps provide lateral stability

Q angle

- Angle between the quads and the patellar tendon. - How can we measure it? (( drawing a line from the ASIS to the midpoint of the patella, and from the tibial tuberosity to the midpoint of the patella)) - It should range between 13-18 degrees in normal individuals in extension - Who tends to have higher angles? Why? (( females b/c the pelvis is wider in women)) - This angle measuring less or greater than the range can cause all kinds of patella injuries

Knee joint

- Appears to be simple, however pretty complex - It is one of the most frequently injured joints because?---ANSWER: is supported and maintained entirely by muscles and ligaments with no bony stability, and it is exposed to more frequent severe stresses and strains - Knee joint is the largest in the body - Synovial - Flexion and extension-0-135 degrees - Not a true hinge because it has a rotational component (accessory motion only)

Joint motion

- Convex femoral condyles move on the concave tibial condyles - The articular surface of the femoral condyles is much greater than that of the tibial - The articular surface of the femoral medial condyle is longer than that of the lateral condyle

Common knee pathologies

- Genu valgum= - Genu varum= - Malalignment at one joint often affects alignment elsewhere. Ex. Hip - Genu recurvatum - Jumper's knee or patellar tendinitis - Osgood-schlatters - Bakers cyst—is it really a cyst?

Bones and landmarks of the knee

- Intercondylar eminence - Medial condyle - Lateral condyle - Plateau - Tibial tuberosity - Fibula-lateral and smaller, set posteriorly to tibia. The fibula is not part of the knee joint because it does not articulate with the femur. - Patella-triangular shaped sesmoid bone within the quadriceps muscle tendon.

Medial and lateral meniscus

- Lateral is o shaped and medial is c shaped - They are both wedge shaped fibrocartilage disks located on the superior surface of the tibia and used for? - They also help to deepen the joint surface because they are thicker laterally. - Which is more frequently injured? ((medial meniscus))

Ligaments and other structures of the knee

- Ligaments and muscles hold the knee together. - Cruciate and collateral ligaments - Cruciate ligaments are located within the joint capsule and called intracapsular - Cruciates cross each other within the joint - ACL=attaches to the anterior surface of the medial tibia and travels superiorly and posteriorly to the lateral condyle of the femur. - PCL=attaches to the posterior tibia and runs superiorly and anterior to the medial femur.

Pes anserine

- Means "goose foot" - What muscles attach here? ( sartorius, gracilis, semitendinosus) - Attach on the anterior medial surface of the proximal tibia.

Common pathologies cont.

- Patellofemoral pain sydrome=anterior knee pain caused by increased Q angle, patella alta, quad weakness or tightness, foot pronation - Chrondromalacia patella - Prepatellar bursitis—housemaid's knee - Unhappy or terrible triad

Bursa

- Purpose is to reduce friction - 13 in the knee joint - Why are they needed? ( the manytendons located around the knee have a relatively vertical line of pull against bony areas of other tendons) - Prepatellar - Suprapatellar - Superficial and deep infrapatellar - Pes anserine

Popliteal space

- The area behind the knee - Contains nerves and arteries. Which? (tibial and common peroneal - Diamond shape bound by the semimembranosus and semitendinosus, biceps femoris, medial and lateral heads of gastroc.

Knee joint cont.

- The articular surface of the femoral condyles is much greater than that of the tibial condyles. - If the femur rolled on the tibia from flexion to extension it would roll off. However, the femur glides posteriorly on the tibia as it rolls in extension. - The articular surface of the medial condyle is longer than that of the lateral condyle. Because of this the medial condyle has to rotate medially on the tibia as it goes into weight bearing extension

knee joint cont...

- What is the articulation between the femur and patella called? (patellofemoral joint) - The posterior surface of the patella should be smooth and glide over the femur. What does the patella do? (increasing the mechanical advantage of the quads and protecting the knee joint) - The patella is encased within the ?

Popliteus

- a one jointed muscle deep in the popliteal space between the two gastroc heads. Responsible for unlocking the screw home mechanism.

Genu valgum

- also called knock knees - an alignment of the lower extremity in which the ankles are positioned more laterally than normal

Genu recurvaturm

- also known as back knees - the positioning of the tibiofemoral joint in which ROM goes beyond 0 degrees of extension

Genu varum

- also known as bowlegs - the opposite alignment problem in which the ankles are positioned more medially than normal

Unhappy or terrible triad

- knee injury caused by a single blow to the knee and involves tears to the ACL, the medial collateral ligament and the medial meniscus

Prepatellar bursitis—housemaid's knee

- occurs when there is constant pressure between the skin and the patella

Muscles of the knee

- quads - Hamstrings - popliteus - gastrocnemius - Tensor fascia latae - Gracilis and sartorius

Quads

- rectus femoral muscle **O: AIIS, I: TIBIAL TUBEROSITY A: HIP FLEXION,KNEE EXTENSION - vastus lateralis muscle **O: linea aspera I: tibial tuberosity A: knee extension -vastus medialus muscle ** O: linea aspera I: tibial tuberosity A: knee extension - vastus intermedialis ** O: anterior femur I: tibial tuberosity A: knee extesion -- They all blend together. --Femoral nerve is the innervation.

Hamstrings

- semimembranosus ** O: ischial tuberosity I: posterior surface of medial condyle A: extend hip and flex knee - semitendinosus ** O: ischial tuberosity I: anteromedial surface of proximal tibia A: extend hip and flex knee - biceps femoris ** O: ischial tuberosity I: fibular head A: extend hip and flex knee

Chrondromalacia patella

- the softening and degeneration of the cartilage on the posterior aspect of the patella causing anterior knee pain.

Gastrocnemius

- two jointed, strong plantar flexor and contributor to knee flexion. In a closed chain action with the foot planted , the proximal thigh can move into knee extension. The gastroc can help if the quads are not functional.

Gracilis and sartorius

=span knee medially and contribute to medial stability.