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How Posterior Cruciate Ligament Injury Occur edit

 
In this medial view of the flexed knee, the lateral femoral condyle has been removed to reveal the structure of the PCL. Because the anterolateral bundle is stretched and the posteromedial bundle relaxed during flexion, excessive flexion in the form of hyperflexion causes tensile stress, shown in red, on the anterolateral bundle of the PCL that leads to PCL injury.

Related Anatomy of the PCL edit

To understand how Posterior Cruciate Ligament (PCL) injury can occur, one must consider the anatomical and physiological properties of the PCL. The PCL is located within the knee joint where it stabilizes the articulating bones, particularly the femur and the tibia, during movement. It originates from the lateral edge of the medial femoral condyle and the roof of the intercondyle notch [1] then stretches, at a posterior and lateral angle, toward the posterior of the tibia just below its articular surface [2] [3] [4] [5].

 
In this medial view of the extended knee, the lateral femoral condyle has been removed to reveal the structure of the PCL. Because the posteromedial bundle is stretched and the anterolateral bundle relaxed during extension, excessive extension in the form of hyperextension causes tensile stress, shown in red, on the posteromedial bundle of the PCL that leads to PCL injury.

Related Physiological Features of the PCL edit

Although each PCLs is a unified unit, they are described as separate anterolateral and posteromedial sections based off where each section's attachment site and function ([6]). During knee joint movement, the PCL rotates [7], [5] such that the anterolateral section stretches in knee flexion but not in knee extension and the posteromedial bundle stretches in extension rather than flexion ([8] [3]).

The Types of Mechanisms that Lead to PCL Injury edit

In this position, the PCL functions to prevent movement of the tibia in the posterior direction ([9], [3]) and to prevent the tilting or shifting of the patella ([10]). However, the respective laxity of the two sections makes the PCL susceptible to injury during hyperflexion, hyperextension ([11]), and in a mechanism known as a dashboard injury ([5]). Because ligaments are viscoelastic (p. 50 [12]) they can handle higher amounts of stress only when the load is increased slowly (p. 30 [13]). When hyperflexion and hyperextension occur suddenly in combination with this viscoelastic behavior, the PCL deforms or tears [11]. In the third and most common mechanism, the dashboard injury mechanism, the knee experiences impact in a posterior direction during knee flexion toward the space above the tibia [11] [6]. These mechanisms occur in excessive external tibial rotation and during falls that induce a combination of extension and adduction of the tibia, which is referred to as varus-extension stress [6], or that occur while the knee is flexed [11].

  1. ^ Amis, AA.; Gupte, CM.; Bull, AM.; Edwards, A. (Mar 2006). "Anatomy of the posterior cruciate ligament and the meniscofemoral ligaments". Knee Surg Sports Traumatol Arthrosc. 14 (3): 257–63. doi:10.1007/s00167-005-0686-x. PMID 16228178.{{cite journal}}: CS1 maint: date and year (link)
  2. ^ Girgis, FG.; Marshall, JL.; Monajem, A. (1975). "The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis". Clin Orthop Relat Res (106): 216–31. doi:10.1097/00003086-197501000-00033. PMID 1126079.
  3. ^ a b c Chandrasekaran, S.; Ma, D.; Scarvell, JM.; Woods, KR.; Smith, PN. (Dec 2012). "A review of the anatomical, biomechanical and kinematic findings of posterior cruciate ligament injury with respect to non-operative management". Knee. 19 (6): 738–45. doi:10.1016/j.knee.2012.09.005. PMID 23022245.{{cite journal}}: CS1 maint: date and year (link)
  4. ^ Edwards, A.; Bull, AM.; Amis, AA. (Mar 2007). "The attachments of the fiber bundles of the posterior cruciate ligament: an anatomic study". Arthroscopy. 23 (3): 284–90. doi:10.1016/j.arthro.2006.11.005. PMID 17349472.{{cite journal}}: CS1 maint: date and year (link)
  5. ^ a b c Voos, JE.; Mauro, CS.; Wente, T.; Warren, RF.; Wickiewicz, TL. (Jan 2012). "Posterior cruciate ligament: anatomy, biomechanics, and outcomes". Am J Sports Med. 40 (1): 222–31. doi:10.1177/0363546511416316. PMID 21803977.{{cite journal}}: CS1 maint: date and year (link)
  6. ^ a b c Malone, AA.; Dowd, GS.; Saifuddin, A. (Jun 2006). "Injuries of the posterior cruciate ligament and posterolateral corner of the knee". Injury. 37 (6): 485–501. doi:10.1016/j.injury.2005.08.003. PMID 16360655.{{cite journal}}: CS1 maint: date and year (link)
  7. ^ DeFrate, LE.; Gill, TJ.; Li, G. (Dec 2004). "In vivo function of the posterior cruciate ligament during weightbearing knee flexion". Am J Sports Med. 32 (8): 1923–8. doi:10.1177/0363546504264896. PMID 15572322.{{cite journal}}: CS1 maint: date and year (link)
  8. ^ Race, A.; Amis, AA. (Jan 1994). "The mechanical properties of the two bundles of the human posterior cruciate ligament". J Biomech. 27 (1): 13–24. doi:10.1016/0021-9290(94)90028-0. PMID 8106532.{{cite journal}}: CS1 maint: date and year (link)
  9. ^ Castle, TH.; Noyes, FR.; Grood, ES. (Nov 1992). "Posterior tibial subluxation of the posterior cruciate-deficient knee". Clin Orthop Relat Res (284): 193–202. PMID 1395293.{{cite journal}}: CS1 maint: date and year (link)
  10. ^ von Eisenhart-Rothe, R.; Lenze, U.; Hinterwimmer, S.; Pohlig, F.; Graichen, H.; Stein, T.; Welsch, F.; Burgkart, R. (2012). "Tibiofemoral and patellofemoral joint 3D-kinematics in patients with posterior cruciate ligament deficiency compared to healthy volunteers". BMC Musculoskelet Disord. 13 (1): 231. doi:10.1186/1471-2474-13-231. PMC 3517747. PMID 23181354.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  11. ^ a b c d Janousek, AT.; Jones, DG.; Clatworthy, M.; Higgins, LD.; Fu, FH. (Dec 1999). "Posterior cruciate ligament injuries of the knee joint". Sports Med. 28 (6): 429–41. doi:10.2165/00007256-199928060-00005. PMID 10623985.{{cite journal}}: CS1 maint: date and year (link)
  12. ^ Hamill, Joseph; Knutzen, Kathleen. (2009). Biomechanical basis of human movemen. Philadelphia: Wolters Kluwer Health/Lippincott Williams and Wilkins. ISBN 978-0-7817-9128-1.
  13. ^ Hamill, Joseph; Knutzen, Kathleen. (2009). Biomechanical basis of human movemen. Philadelphia: Wolters Kluwer Health/Lippincott Williams and Wilkins. ISBN 978-0-7817-9128-1.
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