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CHAPTER OBJECTIVES

CHAPTER OBJECTIVES

At the completion of this chapter, the reader will be able to:

  1. Describe the various types of stress that are applied to the body.

  2. Describe the various physiological processes by which the body adapts to stress.

  3. Define the various common mechanisms of injury.

  4. Describe the etiology and pathophysiology of musculoskeletal injuries associated with various types of body tissue.

  5. Outline the pathophysiology of the healing process and the various stages of healing of the various connective tissues.

  6. Describe the factors that can impede the healing process.

  7. Outline the more common surgical procedures available for musculoskeletal injuries.

  8. Outline the principles behind postsurgical rehabilitation.

  9. Describe the detrimental effects of immobilization.

OVERVIEW

OVERVIEW

Tissues in the body are designed to function while undergoing the stresses of everyday living. Body weight, friction, and air or water resistance are all types of stresses that commonly act on the body. The ability of the tissues to respond to stress is due to their differing viscoelastic properties, with each tissue responding to stress in an individual manner based on design. Maintaining the health of the various tissues is a delicate balance because insufficient, excessive, or repetitive stresses can prove deleterious. Fortunately, most tissues have an inherent ability to self-heal—a process that is an intricate phenomenon.

THE RESPONSE OF TISSUE TO STRESS

Kinetics is the term applied to define the forces acting on the body. Posture and movement are both governed by the body’s ability to control these forces. The same forces that move and stabilize the body also have the potential to deform and injure the body.1 A wide range of external and internal forces are either generated or resisted by the human body during daily activities. Examples of these external forces include ground reaction force, gravity, and applied force through contact. Examples of internal forces include structural tension, joint compression, and joint shear forces (Fig. 2-1). Tissue failure will result if stress is applied too quickly, exceeds the tolerance limits of the tissues, or if it is applied repetitively without sufficient time for recovery.2 This type of failure, which may be a result of an acceleration or deceleration injury, has been termed dynamic overload2:

  • Acceleration. This type, which is typically related to a contact injury, occurs when the body or body parts are stationary or moving slower than the applied force, and the injury-producing force accelerates the body or body part beyond the tissue’s ability to withstand or resist that force. For example, when a soccer player is being tackled and the force of contact by the opposing player’s foot against the lateral aspect of the leg exceeds the medial collateral ligament’s ability to resist the force.

  • Deceleration. In this type of injury, which is not typically related to contact, the body or body parts are rapidly decelerated. Examples include landing from a ...

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