Knee Joint

Lateral collateral ligament (Fibular collateral ligament)

A round, cordlike ligament that attaches to the lateral condyle of the femur and runs down to the head of the fibula. Protects the joint from stresses to the medial side of the knee.

Lesser Trochanter (Femur)

A smaller projection located medially and posteriorly, just distal to the greater trochanter; it provides attachment for the iliopsoas muscle.

Patella

A triangular sesamoid bone within the quadriceps muscle tendon. It has a broad, superior border and a somewhat pointed distal portion.

Neck (Femur)

The narrower portion located between the head and the trochanters.

Genu Varum (bowlegs)

The opposite alignment problem in which the distal segments are positioned more medially than normal. The ankles tend to touch while the knees are apart.

What muscle group does the femoral nerve innervate?

Quadriceps muscle group

What do the cruciates provide?

(1) Stability in the sagittal plane. The ACL keeps the femur from being displaced posteriorly on the tibia. Conversely, it keeps the tibia from being displaced anteriorly on the femur. (2) Tightens during extension, preventing excessive hyperextension of the knee. (3) Tightens during flexion and is injured much less frequently than the ACL.

Plateau (Tibia)

The enlarged proximal end, including the medial and lateral condyles and the intercondylar eminence.

Body (Femur)

The long, cylindrical portion between the bones ends; also called the shaft. It is bowed slightly anteriorly.

From __ degrees of extension, there are approximately ___ to ___ degrees of flexion.

0 degrees of extension, 120-135 degrees of flexion

The knee is composed of the .....

Distal end of the femur articulating with the proximal end of the tibia.

Lateral Condyle (Femur)

Distal lateral end.

Medial Condyle (Femur)

Distal medial end.

The medial collateral ligament provides medial stability and prevents....

Excessive motion if there is a blow to the lateral side of the knee.

True or False: All three types of arthrokinematic motions are used during knee flexion and extension?

True

Screwhome Mechanism of the Knee

When the last few degrees of motion lock the knee in extension.

Because of the attachments of the collateral ligaments are offset posteriorly and superiorly to the axis of flexion, the collateral ligaments tighten during ____, contributing to the stability of the knee, and slacken during ____.

Extension, flexion

The ___ and ___ nerves play a major part in the innervation of the knee joint.

Femoral and sciatic nerves

The knee extensors receive nerve innervation from the ____, which comes off the spinal cord at the higher level than does innervation of the knee flexors.

Femoral nerve

With knee extension, the end feel is ____ due to the tension of the joint capsule and ligaments.

Firm (soft tissue stretch)

What are the motions possible at the knee joint?

Flexion and extension

The femur must ____ on the tibia as it ____ into extension.

Glide posteriorly, rolls into extension

The articular surface of the femoral medial condyle is longer than that of the lateral condyle. As extension occurs, the articular surface of the femoral lateral condyle is used up while some articular surface remains on the medial condole. Therefore, the medial condyle of the femur must also ____ to use its entire articular surface. Because of this during the lat few degrees of weight-bearing extension (closed-chain action) that causes the femur to ____ (rotate ___) on the tibia.

Glide posteriorly, spin (rotate medially)

What muscle group does the sciatic nerve innervate?

Hamstring muscle group

Name the landmarks of the femur significant to the knee:

Head, neck, greater trochanter, lesser trochanter, body, medial condyle, lateral condyle, lateral epicondyle, medial epicondyle, adductor tubercle, linea aspera, pectineal line, patellar surface.

Unlike the elbow joint, the knee is not a true hinge joint because...

It has a rotational component. Rotation is not a free motion but an accessory motion that accompanies flexion and extension.

Tibial Tuberosity (Tibia)

Large projection at the proximal end on the anterior surface in the midline.

Greater Trochanter (Femur)

Large projection located laterally between the neck and the body of the femur, providing attachment for the gluteus medius and minims and for most deep rotator muscles.

The lateral collateral ligament provides stability to the ____ side of the knee.

Lateral

Fibula

Lateral to, and smaller than, the tibia. It is set back from the anterior surface of the tibia, allowing a large space for muscle attachment. Not part of the knee because it does not articulate with the femur.

Patellar Surface (Femur)

Located between the medial and lateral condyle anteriorly. It articulates with the posterior surface of the patella.

Medial and Lateral Menisci

Located on the superior surface of the tibia and are two half-moon, wedge-shaped fibrocartilage disks that are designed to absorb shock.

Cruciate

Located within the joint capsule and are therefore called intracapsular ligaments. Situated between the medial and lateral condyles, they cross each other obliquely. Named for their attachment on the tibia.

Name the O, I, A, & N for the poplitues muscle:

O: lateral condyle of femur I: posterior medial condyle of tibia A: initiates knee flexion N: tibial nerve (L4, L5, S1)

Name the O, I, A, & N for the vastus lateralis muscle:

O: linea aspera I: tibial tuberosity via patellar tendon A: knee extension N: femoral nerve (L2, L3, L4)

Name the O, I, A, & N for the vastus medialis muscle:

O: linea aspera I: tibial tuberosity via patellar tendon A: knee extension N: femoral nerve (L2, L3, L4)

Name the O, I, A, & N for the biceps femoris muscle:

O: long head- ischial tuberosity, short head- lateral lip of line aspera I: fibular head A: long head- extend hip & flex knee, short head- flex knee N: long lead- sciatic nerve (S1, S2, S3), short head- common peroneal nerve (L5, S1, S2)

Name the O, I, A, & N for the gastrocnemis muscle:

O: medial and lateral condyles of femur I: posterior calcaneus A: knee flexion, ankle plantar flexion N: tibial nerve (S1, S2)

Prepatellar Bursitis (housemaid's knee)

Occurs when there is constant pressure between the skin and the patella. Commonly seen in carpet layers and is the result of repeated direct blows or sheering stresses on the knee.

The collateral ligaments supply stability in the ____ plane.

Frontal

Osgood-Schlatter Disease

A common overuse injury among adolescents. It involves the traction-type epiphysis on the tibial tuberosity of growing bone where the tendon of the quadriceps muscle attaches.

Intercondylar Eminence (Tibia)

A double-pointed prominence on the proximal surface at about the midpoint, which extends up into the intercondylar fossa of the femur.

Medial collateral ligament (Tibial collateral ligament)

A flat, broad ligament attaching to the medial condyles of the femur and tibia. Fibers of the medial meniscus are attached to this ligament, which contributes to frequent tearing of the medial meniscus during excessive stress to the medial collateral ligament.

Terrible Triad

A knee injury caused by a single blow to the knee and involves tears to the anterior cruciate ligament, the medial collateral ligament, and the medial meniscus.

Genu Valgum (aka "knock knees")

An alignment of the lower extremity in which the distal segments (ankles) are positioned more laterally than normal. The knees tend to touch while the ankles are apart.

Miserable Malalignment Syndrome

An alignment problem of the lower extremity involving increased ante version of the femoral head and is associated with genu valgus, increased tibial torsion, and a pronated flat foot.

The satorius muscle arises ___ from the iliac spine, the gracilis muscle arises ___ from the pubis, and thesemitendinosus muscle arises ___ from the ischial tuberosity.

Anteriorly from the iliac spine, medially from the pubis, and posteriorly from the ischial tuberosity.

Patellofemoral Joint

Articulation between the femur and patella. The smooth, posterior surface of the patella glides over the patellar surface of the femur.

Anterior cruciate ligament (ACL)

Attaches to the anterior surface of the tibia in the intercondylar area just medial to the medial meniscus. It spans the knee laterally to the posterior cruciate ligament, and it runs in a superior and posterior direction to attach posteriorly on the lateral condyle of the femur.

Posterior cruciate ligament (PCL)

Attaches to the posterior tibia in the intercondylar area, and it runs in a superior and anterior direction on the medial side of the ACL. It attaches to the anterior femur on the medial condyle.

What is the role of the meniscus?

Because they are thicker laterally than medially and because the proximal surfaces are concave, they deepen the relatively flat joint surface of the tibia.

Patellar Tendonitis (jumper's knee)

Characterized by tenderness at the patellar tendon and results from the overuse stress or sudden impact overloading associated with jumping. It is commonly seen in basketball players, high jumpers, and hurdlers.

The convex ___ condyles move on the concave ___ condyles or vise versa, depending upon whether it is an open- or closed-chain activity.

Convex femoral condyles, concave tibial condyles

What is seen in conduction with genus varus?

Coxa valgus

What is seen in conduction with genu valgus?

Coxa varus

What are the two main ligaments that hold the knee together?

Cruciate and collateral ligaments

What are the main functions of the patella?

Increasing the mechanical advantage of the quadriceps muscle and protecting the knee joint.

Name the landmarks of the tibia significant to the knee:

Intercondyler eminence, medial condyle, lateral condyle, plateau, tibial tuberosity

Pes anserine muscle group

Made up of the sartorius, gracilis, and semitendinosus muscles. All cross the knee posteriorly and medially, then join together to attach distally on the anterior medial surface of the proximal tibia.

Name the O, I, A, & N for the rectus femoris muscle:

O: AIIS I: tibial tuberosity via patellar tendon A: hip flexion, knee extension N: femoral nerve (L2, L3, L4)

Name the O, I, A, & N for the vastus intermedialis muscle:

O: anterior femur I: tibial tuberosity via patellar tendon A: knee extension N: femoral nerve (L2, L3, L4)

Name the O, I, A, & N for the semitendinosus muscle:

O: ischial tuberosity I: anteromedial surface of proximal tibia A: extend hip and knee flexion N: sciatic nerve (L5, S1, S2)

Name the O, I, A, & N for the semimebranosus muscle:

O: ischial tuberosity I: posterior surface of medial condyle of tibia A: extend hip and knee flexion N: sciatic nerve (L5, S1, S2)

Gastrocnemius and hamstring muscles provide ___ stability both medially and laterally, and the quadriceps muscles provide ___ stability.

Posterior, anterior

Lateral Epicondyle (Femur)

Projection proximal to the lateral condyle.

Medial Epicondyle (Femur)

Projection proximal to the medial condyle.

Linea Aspera (Femur)

Prominent longitudinal ridge or crest running most of the posterior length.

In knee extension, what is the Q angle?

Ranges from 13-19 degrees in normal individuals. Angle tends to be greater in females because the pelvis is generally wider in women.

Name the anterior muscles of the knee:

Rectus femoris, vastus lateralis, vastus medialis, vastus intermedialis

Patellofemoral Pain Syndrome

Refers to a common problem causing diffuse anterior knee pain. It is generally considered the result of a variety of alignment factors, such as increased Q angle, patella alta (high-riding patella), quadriceps weakness or tightness, weakness of hip lateral rotators, and excessive foot pronation.

Popliteal Cyst (Baker's Cyst)

Refers to any synovial hernia or bursitis involving the posterior aspect of the knee.

Popliteal space

The area behind the knee, and it contains important nerves (tibial and common peroneal) and blood vessels (popliteal artery and vein). Diamond-shaped fossa is bound superiorly on the medial side by the semitendinosus and semimebranosus muscles and by the biceps femurs muscle on the lateral side.

Pectineal Line (Femur)

Runs from below the lesser trochanter diagonally toward the line aspera and provides attachment for the adductor brevis.

Name the posterior muscles of the knee:

Semimembranosus, semitendinosus, biceps femoris muscle

Adductor Tubercle (Femur)

Small projection proximal to the medial epicondyle to which a portion of the adductor magnus muscle attaches.

With knee flexion, the end feel is ____ due to the contact between the muscle bellies of the thigh and leg.

Soft (soft tissue approximation)

What are the two types of end feel at the knee joint?

Soft tissue approximation and soft tissue stretch

Gracilis and Sartorius Muscles

Spane the knee medially, contributing greatly to medial stability.

Tensor fascia latae muscle

Spans the knee laterally, essentially in the middle of the joint axis for flexion and extension. It contributes greatly to lateral stability.

Knee Joint

Supported and maintained entirely by muscles and ligaments with no bony stability, and it frequently is exposed to severe stresses and strains.

What is the classification of the knee joint?

Synovial hinge joint

Q angle (patellofemoral angle)

The angle between the quadriceps muscle (primarily the rectus femuris muscle) and the patellar tendon. It is determined by drawing a line from the anterior superior iliac spine (ASIS) to the midpoint of the patella, and from the tibial tuberosity to the midpoint of the patella.

Calcaneus

The most posterior of the tarsal bones and is commonly known as the heel. It is identified here because it provides attachment for the gastrocnemius muscle.

Genu Recurvatum ("back knees")

The positioning of the tibiofemoral joint in which range of motion goes beyond 0 degrees of extension.

Lateral Condyle (Tibia)

The proximal lateral end.

Medial Condyle (Tibia)

The proximal medial end.

Head (Femur)

The rounded portion covered articulating with the acetabulum.

Chondromalacia Patella

The softening and degeneration of the cartilage on the posterior aspect of the patella, causing anterior knee pain. Abnormal tracking of the patella within the patellofemoral groove causes the patellar articular cartilage to become inflamed, leading to its degeneration.

The popliteus and gastrocemius knee flexor muscles receive nerve innervation from the ____.

Tibial nerve

What is the purpose of the bursa?

To reduce friction and approximately 13 of them are located at the knee joint. Needed because the many tendons located around the knee have a relatively vertical line of pull against bony areas or other tendons.