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Out there in the real world, one athletic trainer experienced the following:

Being an athletic trainer comes with its ups and downs. There are days when you are able to improve an athlete's condition and give him the good news that he can play in the big game. But the lows of the profession hit when you have to tell an athlete that he is out of the sport indefinitely. I remember a situation like this as though it were yesterday. I attended an away football game where one of my players leaped up to catch a ball, and when he landed on the playing field his knee buckled. I experienced a horrible feeling of dread as I ran onto the field to perform a Lachman and Valgus stress test, which were both grossly positive. A magnetic resonance image and a physician's examination confirmed the diagnosis. I just knew the player would undergo knee surgery within the week, causing his career to come to an abrupt end.

Kim Isaac, MS, AT, ATC

Assistant Professor

Assistant Athletic Trainer

Wilmington College

Wilmington, Ohio


learning outcomes

After working through this chapter, you will be able to:

  1. Verbalize the questions to use when obtaining a thorough medical history for an assessment.

  2. Describe the principles of body movement at the knee and the various mechanisms of injury that affect the knee.

  3. Compare and contrast the findings of various special tests and the role of diagnostic tests used during a knee evaluation.

  4. Explain the medical terminology associated with the assessment of musculoskeletal injuries.

  5. Verbalize the standard procedures used for a clinical evaluation of the knee and interpret the findings for differential diagnoses.


Dan Mueller has an altered gait and moderate pain in his left knee. He states that when he was playing shortstop in the baseball game yesterday, he hurt his left knee while fielding a ground ball. Mr. Mueller aggressively lunged forward to catch a wild hit, took a misstep, fell, and hit the ground hard with his left knee flexed to 90 degrees (Fig. 5-1). Mr. Mueller has no history of injuries to his left knee. Mr. Mueller is having a hard time walking, which is apparent from his disrupted gait. He says most of his knee pain is located posteriorly. Upon observation of his left knee, you notice that there is moderate edema located in the popliteal fossa, no visual deformity, and no ecchymosis when compared bilaterally.

Figure 5-1:

Dan Mueller's mechanism of injury.

  1. Based on this scenario, what do you know about Mr. Mueller's injury?

    • Male athlete

    • Baseball shortstop

    • Injury occurred at ...

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