The Knee Joint and Joint Disorders

Chapter 8, Section 3

Knee JointThe knee joint is the largest and most complex synovial joint in body.

Two distal condyles of the femur articulate with two proximal condyles of the tibia. This is a condylar joint.

The femur also articulates anteriorly with the patella. This is a plane joint.

Figure 8.21 Figure 8.20

1. Synovial Membrane• Secretes synovial fluid

2. Joint Cavity • Stores synovial fluid

3. Joint Capsule• Relatively thin support• Reinforced by several

ligaments and tendons

Knee Joint

General structures of a synovial joint in the knee

Figure 8.20

1. Patellar tendon - The patella is partially enclosed in tendons fused together from the thigh muscle.

2. Patellar ligament – continuation of patellar tendon. Extends from patella to the tibial tuberosity.

Knee Joint

Several ligaments and tendons strengthen the knee joint.

Knee Joint

Figure 8.21a Anterior right knee with patella removed.

3. Tibial collateral ligament – connects medial condyle of femur with medial condyle of tibia.

4. Fibular collateral ligament – connects lateral condyle of femur with head of fibula.

5. Anterior & Posterior Cruciate ligaments – provide additional support to medial surface of tibia and femur

Ligaments continued:

Knee Joint

Two menisci (medial & lateral meniscus) separate the femur and tibia, and align them.

Figure 8.20 (a) sagittal section of the knee joint. (b) Photograph of the left knee joint (frontal

section)

Three major bursae surround the knee joint.

Knee Joint

1. Suprapatellar bursa• Largest bursa in body

2. Prepatellar bursa• Between patella and skin• Housemaid’s knee =

prepatellar bursitis

3. Infrapatellar bursa

Figure 8.20a

Joint Disorders

Sprain = overstretching or tearing of connective tissue (tendons, ligaments, or cartilage) associated with a joint.

However, the bones are not disarticulated.

Joint Disorders

Arthritis = inflamed, swollen, and painful joints.

1. Osteoarthritis• Most common arthritis

• Occurs with aging

• Articular cartilage degenerates, causing bone to rub against bone.

• Results in stiff and painful joints

• Fingers may appear gnarled and knee may bulge.

Osteoarthritic fingers often take

on a gnarled appearance.

2. Rheumatoid Arthritis• Autoimmune disorder (immune

system attacks tissue)

• Synovial membrane thickens & becomes inflamed

• Mass of fibrous connective tissue (Pannus) invades synovial space.

• Fibrous pannus destroys articular cartilage, and the joints may swell and ossify.

Knuckles may swell as a result of rheumatoid arthritis.

End of Chapter 8, Section 3

Other symptoms of Rheumatoid Arthritis:• low-grade fever, fatigue, appetite, stiffness.

Joint Disorders