Special Tests: Knee Ligament Tests

Special Tests Covered in this Lesson:

• Ligament Tests
  • Anterior Cruciate Ligament (ACL): Lachman's Test (and Anterior Drawer Test)
  • Medial and Lateral Collateral Ligaments (MCL, LCL): Valgus Stress Test and Varus Stress Tests
  • Posterior Cruciate Ligament (PCL): Posterior Drawer Test and Quadriceps Active Test

Knee special tests for ligament injuries are relatively accurate, and research demonstrates that their inclusion in a routine combination of exams (patient history, movement assessment, radiography, special tests) results in diagnostic accuracy equivalent to MRI. Generally, the occurrence of knee ligament injury is correlated with acute trauma. Anterior cruciate ligament injuries (ACL) injuries are the most commonly reported, especially during sports; however, most traumatic ACL injuries occur in conjunction with some damage to the other large ligament of the knee (e.g. most commonly the collateral ligaments). When compared to the other major ligaments of the knee, posterior cruciate ligament (PCL) injuries are relatively rare, and most often occur in conjunction with damage to other major ligaments. Clinical movement professionals (physical therapists, physical therapy assistants, chiropractors, occupational therapists, athletic trainers, etc.) should be aware of the special tests for ligament injuries, as assessment of a ligament injury should result in referral for further testing and potentially a surgical consultation.

Summary

The routine combination of patient history, physical examination, and radiographs, is as accurate as MRI for diagnosing anterior cruciate ligament (ACL) injury (1, 4-15). This combination of exams is also accurate for posterior cruciate ligament (PCL) injuries (1, 9, 15 - 17), and is specific, but may lack sensitivity, for collateral ligament injuries (1, 16, 17). Unfortunately, the studies themselves lack the details necessary to identify an optimal set of subjective exam questions, special tests, movement assessments, and/or radiographs. At this point, no studies could be located regarding a "test-item cluster" for knee ligament injury; however, based on the reported findings of these studies more consideration should be given to the potential for a knee evaluation cluster.

The tests in the course were chosen to ensure that the major stabilizing ligaments of the knee were assessed, this includes "best tests" for the anterior cruciate ligament (ACL), collateral ligaments, and posterior cruciate ligament (PCL).

• For testing the ACL, current research suggests that Lachman's Test is more accurate than the Anterior Drawer Test (4 - 15, 18 - 37). This is due in large part to the relatively low sensitivity of the Anterior Drawer Test (18-20, 22, 28, 31-33); however, the Anterior Drawer Test has been included in this course due to its common use in practice.
• Collateral ligament tests have been generally understudied. The available research suggests that the Varus Stress Test and Valgus Stress Tests are the best available tests for the lateral collateral ligament (LCL) and medial collateral ligament (MCL); however, they appear to be more sensitive than specific (16, 17, 37 - 42). This implies a negative result may rule out collateral ligament injury, but a positive test should lead to further testing.
• Two tests were chosen for assessing PCL tears in an attempt to improve accuracy. The Posterior Drawer Test exhibits good sensitivity and may be an effective screen. A negative test result likely rules out PCL injury; however, a positive test result should lead to further testing (43 - 45, 47). Although more research investigating the Quadriceps Active Test is recommended, the test demonstrated excellent specificity in several studies, suggesting a positive result is a strong indicator of PCL rupture (47 - 49). This implies the Quadriceps Active Test could be used to confirm the findings of a positive test result on the Posterior Drawer test. Note, to date no research exists investigating the accuracy of these tests combined.
  
  

Brookbush Institute Recommendation:

The Brookbush Institute recommends that all clinical professionals (physical therapists, physical therapy assistants, chiropractors, occupational therapists, athletic trainers, etc.) are aware of these tests. The Lachman's Test , Varus Stress Test, and Valgus Stress Test are accurate tests for assessing ACL, LCL, and MCL injuries, and PCL injuries can be assessed with the Posterior Drawer Test used as a screen, and positive findings confirmed by the Quadriceps Active Test . Assessment of a ligament injury should result in referral for further testing and potentially a surgical consultation.

For an Introduction to Special Tests

• For an introduction to Special Tests including definitions of specific terminology, what special tests measure, accuracy (specificity, sensitivity, reliability, etc.), how we chose the tests in each special test course lessons, and best practice recommendations:
• Special Tests: Introduction

Courses covering Special Tests for the Knee

• Special Tests: Knee Ligament Tests
• Special Tests: Knee - Meniscus Tears, Patellofemoral Pain and Fracture