title: The reliability and diagnostic accuracy of assessing the translation endpoint during the lachman test.
abstract: BACKGROUND
  Interpretation of Lachman testing when evaluating the status of the anterior cruciate ligament (ACL) typically includes a numerical expression classifying the amount of translation (Grade I, II, III) in addition to a categorical modifier (Grade A [firm] or B [absent]) to describe the quality of the passive anterior tibial translation's endpoint. Most clinicians rely heavily on this tactile sensation and place value in this judgment in order to render their diagnostic decision; however, the reliability and accuracy of this endpoint assessment has not been well established in the literature.
  
  
  OBJECTIVE
  The purpose of this study was to determine the intertester reliability of endpoint classification during the passive anterior tibial translation of a standard Lachman test and evaluate the classification's ability to accurately predict the presence or absence of an ACL tear.
  
  
  METHODS
  Prospective, blinded, diagnostic reliability and accuracy study.
  
  
  METHODS
  Forty-five consecutive patients with a complaint of knee pain were independently evaluated for the endpoint classification during a Lachman test by two physical therapists before any other diagnostic assessment. The 21 men and 24 women ranged in age from 20 to 64 years (mean +/- SD age, 40.7 +/- 14) and in acuity of knee injury from 30 to 365 days (mean +/- SD, 238 +/-157).
  
  
  RESULTS
  17 of the 45 patients had a torn ACL. The agreement between examiners on A versus B endpoint classification was 91% with a kappa coefficient of 0.72. In contrast, classification agreement based on the translational amount had an agreement of 65% with a weighted kappa coefficient of 0.52. The sensitivity of the endpoint grade alone was 0.81 with perfect specificity resulting in a positive likelihood ratio of 6.2 and a negative likelihood ratio of 0.19. The overall accuracy of the Lachman test using the endpoint assessment grade alone was 93% with a number needed to diagnose of 1.2.
  
  
  CONCLUSIONS
  Nominal endpoint classification (A or B) from a Lachman test is a reliable and accurate reflection of the status of the ACL. The true dichotomous nature of the test's interpretation (positive vs. negative) is well-served by the quality of the endpoint during passive anterior tibial translation.
  
  
  METHODS
  2.
authors.affiliation: Associate Professor, University of Texas Southwestern Medical Center, School of Health Professions, Department of Physical Therapy, Dallas, TX, USA.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Mulligan
authors.affiliation: Orthopedic Physical Therapy Resident, University of Texas Southwestern Medical Center, School of Health Professions, Department of Physical Therapy, Dallas, TX, USA.
authors.forename: Daniel Q
authors.initials: DQ
authors.lastname: McGuffie
authors.affiliation: Assistant Professor, University of Texas Southwestern Medical Center, Department of Orthopedic Surgery, Dallas, TX, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Coyner
authors.affiliation: Assistant Professor, University of Texas Southwestern Medical Center, Department of Orthopedic Surgery, Dallas, TX, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Khazzam
keywords: ACL; Lachman test; anterior cruciate ligament; diagnosis; knee; reliability; sensitivity; specificity