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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 healing process and the various stages of healing of the connective tissue types.

  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 post-surgical rehabilitation.

  9. Describe the detrimental effects of immobilization.



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 stresses that commonly act on the body. The ability to respond to stress is due to the differing viscoelastic properties of the tissues, with each tissue responding uniquely. Maintaining the health of the various tissues is a delicate balance because insufficient, excessive, or repetitive stresses can prove harmful. Fortunately, most tissues have an inherent ability to self-heal—a process that is an intricate phenomenon.


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 can deform and harm the body. A wide range of external and internal forces are 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 a stress is applied too quickly, exceeds a tissue’s tolerance limits, or is applied repetitively without sufficient time for recovery.1 This type of failure, which may be a result of an acceleration or deceleration injury, has been termed dynamic overload1:

  • 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 tackled from the side, the valgus force’s intensity can exceed a structure’s ability to resist, such as the medial collateral ligament.

  • 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 jump or attempting to stop and quickly change direction (cutting).


Internal forces acting on the body.

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