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A 27-year-old recreational soccer player injures his knee after colliding with an opposing player during a game. On physical exam, his Lachman is graded as 1A. He has laxity to varus stress with the knee flexed to 30 degrees. Dial test of the tibia shows increased external rotation at 30 degrees, but not at 90 degrees in comparison to the contralateral leg. Which of the following structure(s) are torn?
Anterior cruciate ligament (ACL)
Lateral collateral ligament (LCL)
Anterior cruciate ligament (ACL) and lateral collateral ligament (LCL)
Lateral collateral ligament (LCL) and posterolateral corner (PLC)
Posterior cruciate ligament (PCL) and posterolateral corner (PLC)
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The individual in the above scenario likely has torn his lateral collateral ligament (LCL) and posterolateral corner (PLC). The LCL is part of the posterolateral corner, but can be injured in isolation or along with the rest of the posterolateral corner. An isolated LCL tear would be tested by flexing the knee at 30 degrees and applying varus stress. The posterolateral corner can be tested by the dial test, which is done by externally rotating the affected tibia. A PLC injury shows increased external rotation at 30 degrees, while a combined PLC/PCL injury would show increased external rotation at 30 and 90 degrees.
Lubowitz et al review the history and physical examination used in determining ligamentous instability of the knee joint. Ultimately, information must be obtained from multiple tests and imaging to reach the final diagnosis.
Chen et al review isolated posterolateral rotatory instability (PLRI)of the knee. Although these injuries are rare, they do result in significant instability in the knee. In the article, they discuss physical exam maneuvers to distinguish PLC vs PCL injuries. They describe that posterolateral subluxation of the lateral tibial plateau only at 30 degrees is indicative of isolated PLC injury vs subluxation at both 30 and 90 degrees is indicative of combined PLRI and PCL injury.
Attached is a video showing physical exam maneuvers including the dial test which test the posterolateral corner.
1: Isolated ACL injury would have a positive Lachman's test with increased anterior knee translation at 30 degrees of knee flexion. In the given scenario, Grade 1A indicates less than 5mm of translation and a firm endpoint indicating that the ACL is intact.
2: Isolated LCL injury would have increased laxity to varus force at 30 degrees of knee flexion, but would not have a positive dial test.
3: Would have both ACL and LCL findings as above.
5: Would have increased external rotation of tibia at both 30 and 90 degrees of knee flexion.
Lubowitz JH, Bernardini BJ, Reid JB 3rd.
Am J Sports Med. 2008 Mar;36(3):577-94. Epub 2008 Jan 24. PMID: 18219052 (Link to Abstract)
Chen FS, Rokito AS, Pitman MI.
J Am Acad Orthop Surg. 2000 Mar-Apr;8(2):97-110. PMID: 10799095 (Link to Abstract)
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In relation to the femoral insertion of the popliteus, the femoral attachment of the lateral collateral ligament is
posterior and proximal
posterior and distal
anterior and proximal
anterior and distal
LaPrade in a cadaveric study of 10 knees found that the lateral (or fibular) collateral ligament (LCL) had an average femoral attachment 1.4mm proximal and 3.1mm posterior to the lateral epicondyle. The popliteus has a broad-based femoral attachment at the most proximal and anterior fifth of the popliteal sulcus and always attaches anterior to the fibular collateral ligament. Thus, the LCL's femoral attachment is posterior and proximal compared to the popliteus femoral insertion with the average distance between their femoral attachments being 18.5 mm. See illustration from article (FCL=LCL, popliteus=PLT)
LaPrade RF, Ly TV, Wentorf FA, Engebretsen L
Am J Sports Med. 2003 Nov-Dec;31(6):854-60. PMID: 14623649 (Link to Abstract)
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HPI - 17 year old obese female. BMI 37.2
Playing football with friends. Twisted knee and heard a pop and swelling.
MRI shows acl tear and medial meniscus tear, but standing xrays show significant lateral joint widening.
Full length scanogram shows significant varus alignment.
Difficult to really evaluate posterior lateral corner structures due to obese knee. I did not appreciate any increased external rotation.
What to do for this young pt?
ACL reconstruction alone?
ACL and HTO?
What surgery would you perform?
Video demonstrates lateral collateral ligament (LCL tear). Knee is flexed 30 deg...