Posterior cruciate ligament tear
Citation, DOI & article data
Posterior cruciate ligament (PCL) tears are less common than anterior cruciate ligament tears.
Posterior cruciate ligament tears account for ~10% (range 2-23%) of all knee injuries 2.
Posterior cruciate ligament injuries are isolated in only 30% of cases and are thus commonly associated with other injuries 1,2.4:
- ligamentous injury (~40%)
- meniscal tears
- posterolateral corner injury 5
- bone contusion (80%) or avulsion fracture (<10%)
- knee joint effusion
Sports injuries and car accidents (dashboard injury) are equally responsible for these injuries 1. Many patients will be asymptomatic and their clinical examination is unremarkable. However, some patients may have knee instability or posterior sag sign.
Three mechanisms of injury have been proposed 2:
- posterior tibial displacement in a flexed knee
- rotation with an abduction or adduction force
Features of posterior cruciate ligament tears include 1,2:
- PCL usually remains contiguous (~70%) although there may be complete or partial ligamentous disruption
- absent PCL replaced by high T1 and T2 signal
- enlarged and swollen PCL: >7 mm AP diameter of the vertical portion on sagittal imaging is indicative of a tear
- posterior tibial translation of >2-3 mm measured in the mid medial compartment 6,7
Treatment and prognosis
Posterior cruciate ligament tears may result in chronic instability and early degenerative change 2.
- posterior cruciate ligament tears can spontaneously heal and commonly demonstrate fiber continuity on MRI, however, these fibers may heal in a non-functional, lax, elongated position, which can result in knee joint degeneration 7,8
- posterior tibial translation on kneeling posterior stress radiographs of >5 mm 9 or >2-3 mm on MRI are signs of chronic posterior cruciate ligament (PCL) or PCL graft tears 6,7
- 1. Rodriguez W, Vinson E, Helms C, Toth A. MRI Appearance of Posterior Cruciate Ligament Tears. AJR Am J Roentgenol. 2008;191(4):1031. doi:10.2214/AJR.07.2921 - Pubmed
- 2. Sonin A, Fitzgerald S, Hoff F, Friedman H, Bresler M. MR Imaging of the Posterior Cruciate Ligament: Normal, Abnormal, and Associated Injury Patterns. Radiographics. 1995;15(3):551-61. doi:10.1148/radiographics.15.3.7624562 - Pubmed
- 3. Mohankumar R, White L, Naraghi A. Pitfalls and Pearls in MRI of the Knee. AJR Am J Roentgenol. 2014;203(3):516-30. doi:10.2214/AJR.14.12969 - Pubmed
- 4. Wolfgang Dähnert. Radiology Review Manual. (2011) ISBN: 9781609139438 - Google Books
- 5. Vinson E, Major N, Helms C. The Posterolateral Corner of the Knee. AJR Am J Roentgenol. 2008;190(2):449-58. doi:10.2214/AJR.07.2051 - Pubmed
- 6. DePhillipo N, Cinque M, Godin J, Moatshe G, Chahla J, LaPrade R. Posterior Tibial Translation Measurements on Magnetic Resonance Imaging Improve Diagnostic Sensitivity for Chronic Posterior Cruciate Ligament Injuries and Graft Tears. Am J Sports Med. 2017;46(2):341-7. doi:10.1177/0363546517734201 - Pubmed
- 7. Degnan A, Maldjian C, Adam R, Harner C. Passive Posterior Tibial Subluxation on Routine Knee MRI as a Secondary Sign of PCL Tear. Radiol Res Pract. 2014;2014:1-6. doi:10.1155/2014/715439 - Pubmed
- 8. Jung Y, Jung H, Yang J et al. Characterization of Spontaneous Healing of Chronic Posterior Cruciate Ligament Injury: Analysis of Instability and Magnetic Resonance Imaging. J Magn Reson Imaging. 2008;27(6):1336-40. doi:10.1002/jmri.21333 - Pubmed
- 9. Jackman T, LaPrade R, Pontinen T, Lender P. Intraobserver and Interobserver Reliability of the Kneeling Technique of Stress Radiography for the Evaluation of Posterior Knee Laxity. Am J Sports Med. 2008;36(8):1571-6. doi:10.1177/0363546508315897 - Pubmed