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Lateral collateral ligament injury and related posterolateral corner injuries of the knee

Sean N Martin, DO
Kevin deWeber, MD, FAAFP, FACSM
Section Editor
Karl B Fields, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM


Isolated injuries of the lateral collateral ligament (LCL) are among the least common knee injuries but can occur when the joint is struck from the inside (varus stress). More commonly, the LCL is injured along with other structures, often including those of the posterolateral corner of the knee but also possibly the anterior or posterior cruciate ligaments, during more significant trauma. The care of uncomplicated, minor LCL injuries can be supervised by primary care clinicians, but more severe injuries warrant orthopedic referral.

The presentation, evaluation, diagnosis, and nonoperative management of LCL injuries are reviewed here. Other knee injuries and an overall approach to knee complaints in active adults are discussed separately. (See "Approach to the athlete or active adult with knee pain" and "Anterior cruciate ligament injury" and "Meniscal injury of the knee" and "Medial collateral ligament injury of the knee" and "Patellofemoral pain".)


The lateral collateral ligament (LCL) works in concert with the other soft tissue structures of the arcuate ligament complex to provide posterolateral stability to the knee [1]. The primary posterolateral stabilizing structures are commonly considered to be the LCL, popliteus tendon, and the popliteofibular ligament (PFL). Other stabilizing structures include the biceps femoris and lateral gastrocnemius muscles and tendons; and the popliteal meniscal, fabellofibular, oblique popliteal, and arcuate ligaments [2].

In addition, as an independent structure, the LCL acts as a barrier to varus instability at all angles of knee flexion [3]. The LCL may also act with the other primary posterolateral structures to prevent posterior translation [4] and external rotation of the tibia on the femur during early knee flexion (0 to 30 degrees) [5,6]. As knee angles increase beyond 60 degrees, the LCL provides less restraint against external rotation compared to the PFL [6], and beyond 70 degrees, it does not provide significant resistance to external rotation [7].


Injury to the lateral collateral ligament (LCL) represents approximately 8 percent of all knee injuries, making it the second least commonly injured knee ligament, the posterior cruciate ligament being the least injured [8]. Of the knee injuries treated in this study, the LCL was involved in 2.5 percent of cases. In one large retrospective study, approximately 48.9 percent of cases involving LCL injuries were treated with surgery, but half of these cases involved multiple injuries [9]. Data pertaining to the epidemiology of posterolateral corner knee injuries are extremely limited, but such injuries are often associated with injuries to other knee ligaments [10,11].


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Literature review current through: Sep 2016. | This topic last updated: May 13, 2015.
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  1. Hughston JC, Andrews JR, Cross MJ, Moschi A. Classification of knee ligament instabilities. Part II. The lateral compartment. J Bone Joint Surg Am 1976; 58:173.
  2. Recondo JA, Salvador E, Villanúa JA, et al. Lateral stabilizing structures of the knee: functional anatomy and injuries assessed with MR imaging. Radiographics 2000; 20 Spec No:S91.
  3. Lasmar RC, Marques de Almeida A, Serbino JW Jr, et al. Importance of the different posterolateral knee static stabilizers: biomechanical study. Clinics (Sao Paulo) 2010; 65:433.
  4. Kim YH, Purevsuren T, Kim K, Oh KJ. Contribution of posterolateral corner structures to knee joint translational and rotational stabilities: a computational study. Proc Inst Mech Eng H 2013; 227:968.
  5. Chun YM, Kim SJ, Kim HS. Evaluation of the mechanical properties of posterolateral structures and supporting posterolateral instability of the knee. J Orthop Res 2008; 26:1371.
  6. Lim HC, Bae JH, Bae TS, et al. Relative role changing of lateral collateral ligament on the posterolateral rotatory instability according to the knee flexion angles: a biomechanical comparative study of role of lateral collateral ligament and popliteofibular ligament. Arch Orthop Trauma Surg 2012; 132:1631.
  7. Sugita T, Amis AA. Anatomic and biomechanical study of the lateral collateral and popliteofibular ligaments. Am J Sports Med 2001; 29:466.
  8. Swenson DM, Collins CL, Best TM, et al. Epidemiology of knee injuries among U.S. high school athletes, 2005/2006-2010/2011. Med Sci Sports Exerc 2013; 45:462.
  9. Majewski M, Susanne H, Klaus S. Epidemiology of athletic knee injuries: A 10-year study. Knee 2006; 13:184.
  10. Ranawat A, Baker CL 3rd, Henry S, Harner CD. Posterolateral corner injury of the knee: evaluation and management. J Am Acad Orthop Surg 2008; 16:506.
  11. LaPrade RF, Wentorf FA, Fritts H, et al. A prospective magnetic resonance imaging study of the incidence of posterolateral and multiple ligament injuries in acute knee injuries presenting with a hemarthrosis. Arthroscopy 2007; 23:1341.
  12. Hill OT, Bulathsinhala L, Scofield DE, et al. Risk factors for soft tissue knee injuries in active duty U.S. Army soldiers, 2000-2005. Mil Med 2013; 178:676.
  13. Meister BR, Michael SP, Moyer RA, et al. Anatomy and kinematics of the lateral collateral ligament of the knee. Am J Sports Med 2000; 28:869.
  14. Wilson WT, Deakin AH, Payne AP, et al. Comparative analysis of the structural properties of the collateral ligaments of the human knee. J Orthop Sports Phys Ther 2012; 42:345.
  15. Brinkman JM, Schwering PJ, Blankevoort L, et al. The insertion geometry of the posterolateral corner of the knee. J Bone Joint Surg Br 2005; 87:1364.
  16. LaPrade RF, Ly TV, Wentorf FA, Engebretsen L. The posterolateral attachments of the knee: a qualitative and quantitative morphologic analysis of the fibular collateral ligament, popliteus tendon, popliteofibular ligament, and lateral gastrocnemius tendon. Am J Sports Med 2003; 31:854.
  17. Yan J, Sasaki W, Hitomi J. Anatomical study of the lateral collateral ligament and its circumference structures in the human knee joint. Surg Radiol Anat 2010; 32:99.
  18. Levy BA, Stuart MJ, Whelan DB. Posterolateral instability of the knee: evaluation, treatment, results. Sports Med Arthrosc 2010; 18:254.
  19. Bahk MS, Cosgarea AJ. Physical examination and imaging of the lateral collateral ligament and posterolateral corner of the knee. Sports Med Arthrosc 2006; 14:12.
  20. LaPrade RF, Wentorf F. Diagnosis and treatment of posterolateral knee injuries. Clin Orthop Relat Res 2002; :110.
  21. LaPrade RF, Ly TV, Griffith C. The external rotation recurvatum test revisited: reevaluation of the sagittal plane tibiofemoral relationship. Am J Sports Med 2008; 36:709.
  22. Hughston JC, Norwood LA Jr. The posterolateral drawer test and external rotational recurvatum test for posterolateral rotatory instability of the knee. Clin Orthop Relat Res 1980; :82.
  23. Jakob RP, Hassler H, Staeubli HU. Observations on rotatory instability of the lateral compartment of the knee. Experimental studies on the functional anatomy and the pathomechanism of the true and the reversed pivot shift sign. Acta Orthop Scand Suppl 1981; 191:1.
  24. LaPrade RF, Terry GC. Injuries to the posterolateral aspect of the knee. Association of anatomic injury patterns with clinical instability. Am J Sports Med 1997; 25:433.
  25. Stiell IG, Greenberg GH, Wells GA, et al. Derivation of a decision rule for the use of radiography in acute knee injuries. Ann Emerg Med 1995; 26:405.
  26. Lee J, Papakonstantinou O, Brookenthal KR, et al. Arcuate sign of posterolateral knee injuries: anatomic, radiographic, and MR imaging data related to patterns of injury. Skeletal Radiol 2003; 32:619.
  27. Juhng SK, Lee JK, Choi SS, et al. MR evaluation of the "arcuate" sign of posterolateral knee instability. AJR Am J Roentgenol 2002; 178:583.
  28. LaPrade RF, Heikes C, Bakker AJ, Jakobsen RB. The reproducibility and repeatability of varus stress radiographs in the assessment of isolated fibular collateral ligament and grade-III posterolateral knee injuries. An in vitro biomechanical study. J Bone Joint Surg Am 2008; 90:2069.
  29. LaPrade RF, Gilbert TJ, Bollom TS, et al. The magnetic resonance imaging appearance of individual structures of the posterolateral knee. A prospective study of normal knees and knees with surgically verified grade III injuries. Am J Sports Med 2000; 28:191.
  30. Geiger D, Chang E, Pathria M, Chung CB. Posterolateral and posteromedial corner injuries of the knee. Radiol Clin North Am 2013; 51:413.
  31. Pacheco RJ, Ayre CA, Bollen SR. Posterolateral corner injuries of the knee: a serious injury commonly missed. J Bone Joint Surg Br 2011; 93:194.
  32. Vinson EN, Major NM, Helms CA. The posterolateral corner of the knee. AJR Am J Roentgenol 2008; 190:449.
  33. Sekiya JK, Swaringen JC, Wojtys EM, Jacobson JA. Diagnostic ultrasound evaluation of posterolateral corner knee injuries. Arthroscopy 2010; 26:494.
  34. Radhakrishna M, Macdonald P, Davidson M, et al. Isolated popliteus injury in a professional football player. Clin J Sport Med 2004; 14:365.
  35. Garrick JG, Webb DR. Sports Injuries: Diagnosis and Management, WB Saunders, Philadelphia 1999. p.326.
  36. Solger EA, Schweim JJ, Tripp PM. Proximal and distal tibofibular syndesmosis injury in a collegiate football athlete. Human Kinetics 2013; 18:24.
  37. LaPrade RF, Wentorf FA, Crum JA. Assessment of healing of grade III posterolateral corner injuries: an in vivo model. J Orthop Res 2004; 22:970.
  38. Babwah T. Common peroneal neuropathy related to cryotherapy and compression in a footballer. Res Sports Med 2011; 19:66.
  39. Salata MJ, Gibbs AE, Sekiya JK. The effectiveness of prophylactic knee bracing in american football: a systematic review. Sports Health 2010; 2:375.