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  • ACL sprain

  • ACL partial tear

  • ACL full-thickness tear


  • 717.83 Old disruption of anterior cruciate ligament

  • 844.2 Sprain of cruciate ligament of knee


  • M23.50 Chronic instability of knee, unspecified knee

  • S83.509A Sprain of unspecified cruciate ligament of unspecified knee, initial encounter


  • 4I: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion (ROM) Associated with Bony or Soft Tissue Surgery


Patient is a 17-year-old high school soccer player who injured her left knee in a noncontact injury. She was assessed on the field with a positive Lachman and anterior drawer test. The patient went the next day for follow-up with the physician and the MRI showed a completely torn anterior cruciate ligament (ACL). The patient was referred to physical therapy to decrease swelling and increase ROM. The patient had a negative varus and valgus stress tests and a negative McMurray test. The patient has 3 mm of anterior laxity on her right knee and 9 mm of laxity of the left using a KT-1000 at 20 lbs. The patient is scheduled for a consult for a possible autograft surgery in 4 weeks.



  • ACL made up of two bundles

    • Anteromedial (AM) bundle: Anteromedially on the tibia and more proximal on the femoral side

    • Posterolateral (PL) bundle: Relatively PL

    • Parallel orientation in extension

    • Crossed orientation in flexion

  • American Medical Association (AMA) has developed standard nomenclature for athletic injuries to ligamentous structures1

    • First-degree sprain: Minor tear of ligament fibers

    • Second-degree sprain: Partial tear of ligament structure

    • Third-degree sprain: Complete tear of ligament

FIGURE 188-1

Sagittal T2-weighted fat-saturated MR image of the knee showing a normal ACL (arrow). Notice the fascicular arrangement. (From Chen MYM, Pope TL, Ott DJ. Basic Radiology. 2nd ed. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)

Essentials of Diagnosis

  • Clinical diagnosis of a partial tear1

    • Asymmetric Lachman test

    • Negative pivot-shift test

    • KT-1000 arthrometer test ≤3 mm

    • Confirming arthroscopic observation

  • Medial and lateral menisci and medial collateral ligament (MCL) are commonly injured with the ACL2

  • History

    • Contact injuries: Typically due to application of varus or valgus force to the knee imposing a shear force on the joint

    • Risk for injury increased by2

      • Sudden deceleration

      • Abrupt change in direction

      • Hyperextension of the knee

    • Noncontact injuries (70% of ACL injuries3) typically due to4

  • Deceleration and change in direction (cutting maneuvers)

  • Landing from a jump in full knee extension

  • Pivoting with planted foot and extended knee

  • Hyperextension/Flexion of the knee

General Considerations

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