Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

8. Joints

Joint Movements

Anatomy & Physiology

8. Joints

Joint Movements

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Problem L3.2

Textbook Question

Lauren has hurt her knee playing soccer. She explains that during the match, someone tackled her, hitting her on the lateral side of her knee. You notice during your examination that she has excessive range of motion in her knee; specifically, you are able to hyperextend her knee and anteriorly displace her tibia on her femur. Her tibia also displaces laterally on her femur. What has likely happened to her knee? Explain.

Verified step by step guidance

Step 1: Begin by identifying the anatomical structures involved in Lauren's injury. The knee joint is composed of the femur (thigh bone), tibia (shin bone), patella (kneecap), and several ligaments that stabilize the joint, including the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL).

Step 2: Analyze the mechanism of injury described. Lauren was tackled on the lateral side of her knee, which likely caused a forceful valgus stress (inward bending of the knee) and lateral displacement of the tibia relative to the femur. This type of impact can damage the ligaments responsible for stabilizing the knee joint.

Step 3: Evaluate the symptoms observed during the examination. Hyperextension of the knee and anterior displacement of the tibia on the femur suggest damage to the anterior cruciate ligament (ACL), which prevents anterior movement of the tibia. Lateral displacement of the tibia indicates potential injury to the lateral collateral ligament (LCL), which resists lateral forces.

Step 4: Consider the possibility of additional injuries. The excessive range of motion and instability in the knee may also involve damage to other stabilizing structures, such as the menisci (cartilage that cushions the knee) or the joint capsule. A comprehensive assessment, including imaging studies like MRI, would be necessary to confirm the extent of the injury.

Step 5: Summarize the likely diagnosis. Based on the mechanism of injury and observed symptoms, Lauren has likely sustained a combination of ligament injuries, including an ACL tear and LCL damage. These injuries compromise the stability of the knee joint and require medical intervention, potentially including physical therapy or surgical repair.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Knee Anatomy

The knee joint is a complex structure composed of bones, ligaments, tendons, and cartilage. Key components include the femur, tibia, fibula, and patella, along with ligaments such as the anterior cruciate ligament (ACL) and the medial and lateral collateral ligaments (MCL and LCL). Understanding the anatomy is crucial for diagnosing injuries, as it helps identify which structures may be compromised during trauma.

Ligament Injuries

Ligament injuries, such as sprains or tears, often occur due to excessive force or abnormal movement patterns. In Lauren's case, the lateral impact during the tackle may have stressed the MCL or caused an ACL injury, leading to instability and excessive range of motion. Recognizing the signs of ligament damage is essential for determining the appropriate treatment and rehabilitation.

Joint Stability and Range of Motion

Joint stability refers to the ability of a joint to maintain its position and function under stress, while range of motion (ROM) indicates the extent of movement possible at a joint. In Lauren's situation, hyperextension and lateral displacement of the tibia suggest a loss of stability, likely due to ligamentous injury. Understanding the relationship between stability and ROM is vital for assessing joint injuries and planning recovery strategies.