Lachman test
{{Short description|Clinical test to diagnose injury to ligaments}}
The Lachman test is a clinical test used to diagnose injury of the anterior cruciate ligament (ACL). It is recognized as reliable, sensitive, and usually superior to the anterior drawer test.{{cite journal | title=Methods to diagnose acute anterior cruciate ligament rupture: a meta-analysis of physical examinations with and without anaesthesia |vauthors=van Eck CF, van den Bekerom MP, Fu FH, Poolman RW, Kerkhoffs GM | date=Aug 2013 | journal=Knee Surg Sports Traumatol Arthrosc | volume=21 | issue = 8 | pages=1895–903 | pmid=23085822 | doi=10.1007/s00167-012-2250-9 }}
Description
The knee is flexed at 15 degrees with the patient supine.{{cite web |url=http://www.wheelessonline.com/ortho/Lachman_test |title=Lachman Test |work=Wheeless' Textbook of Orthopaedics }} The examiner should place one hand behind the tibia and the other grasping the patient's thigh. It is important that the examiner's thumb be on the tibial tuberosity.Bates', Lynn. [https://www.inkling.com/read/bates-guide-physical-examination-lynn-bickley-10th/chapter-16/examination-of-specific-joints?s9sig=b95c208b30977f82f1430dfbbccfdcf16ce2a7dd#099f36dd77913f2db7ee880c63f6a431 Bate's Guide to Physical Examination and History Taking]. Lippincott Williams & Wilkins, 2008, p. 632. The tibia is pulled forward to assess the amount of anterior motion of the tibia in comparison to the femur. An intact ACL should prevent forward translational movement ("firm endpoint") while an ACL-deficient knee will demonstrate increased forward translation without a decisive endpoint - a soft or mushy endpoint indicative of a positive test. More than about 2 mm of anterior translation compared to the uninvolved knee suggests a torn ACL ("soft endpoint"), as does 10 mm of total anterior translation. An instrument called a "KT-1000" can be used to determine the magnitude of movement in millimetres. This test can be done in either an on-field evaluation in acute injury, or in a clinical setting when a patient presents for follow-up with knee pain.
Interpretation
The test may be negative in chronic ruptures as the ACL stump can scar to the PCL.{{cite book | chapter=Clinical Examination |author1=N. S. Williams |author2=C. J. K. Bulstrode |author3=P. R. O'Connell | date=2008 | title=Bailey & Love's Short Practice of Surgery| edition=25th | pages=447 }}
History and etymology
The test is named after orthopaedic surgeon John Lachman, late Chairman of the Department of Orthopaedic Surgery and Sports Medicine at Temple University School of Medicine in Philadelphia, Pennsylvania. The original description was submitted by one of his colleagues, JS Torg.{{cite journal | title=Lachman test evaluated. Quantification of a clinical observation |vauthors=Gurtler RA, Stine R, Torg JS | date=Mar 1987 | journal=Clin Orthop Relat Res | volume=216 | pages=141–50 | pmid=3815941 }}