- The PCL consists of 2 bundles, PM & AL bundles
- The 2 PCL bundles are named according to their femur and tibia attachment:
- PM bundle inserting posteriorly to femur & medial to the tibia and the larger AL bundle inserting anterior to the femur & lateral to the tibia.
- PCL lies within its own synovial sheath.
- PCL length :32-38mm, mid cross-sectional area of 11 mm2.
- Average femoral footprint: 209 ± 33.82 mm2, with the mean area of the AL bundle measuring 118 ± 23.95 mm2 and PM bundle measuring 90 ± 16.13 mm2 (Matava M J et al)
Posterior Cruciate Ligament (PCL)
Posterior Cruciate Ligament (PCL)
PCL anatomy
Lateral view
Axial view
PCL tibia attachment
PCL tibia insertion
- PCL attachment on fovea/facet
- Attachment is 10-15mm distal to joint line
- Posterior horn of medial meniscus being the most anterior to PCL
PCL Biomechanics
- AL bundle is 1,120 ± 362 N
- PM bundle is 419 ± 128 N
- PCL has non-isometric behaviour throughout knee range motion
- AL bundle more vertical from 0° to 120° of knee flexion
- The PM bundle becomes shorter and more horizontal with knee flexion
- Meniscofemoral ligaments provide additional structural PCL support: Anterior meniscofemoral ligament is taut in knee flexion and the posterior meniscofemoral ligament is taut in knee extension
Effect of knee flexion and PCL bundle orientation
Knee extension PM bundle more vertical while in flexion AL bundle more vertical
Lateral collateral ligament(LCL) and posterolateral structures
Right knee: LCL
Left knee: Popliteus posterior view
Left knee: Popliteus lateral view
PCL Injury Mechanism
Non-contact injury mechanism:
Knee hyperextension
↑ Flexion
Motor vehicle accidents common cause of PCL injury: posteriorly directed force with the flexed knee during dashboard injury with a posterior-directed force applied to the tibia.
Athletic injury: most commonly a fall on the flexed knee with a plantarflexed foot and hyperflexion of the knee.
The PCL and posterior capsule can also be torn by a hyperextension mechanism.
Injury Classification
Classification based on degree of increased posterior tibia translation:
- Grade I: 1 to 5 mm
- Grade II: 6 to 10 mm
- Grade III: >10 mm
PCL clinical assessment: Anterior and Posterior drawer tests are used for testing ACL & PCL respectively. Make sure the knee is in an anatomic position (reduce any subluxation) before performing either test.
Associated injury to lateral collateral & posterolateral corner
MCL and Meniscus tears
- PCL tear may be be associated with meniscus tears
- Variation in meniscus tear pattern
Common meniscus tear patterns
PCL injury may be related to knee dislocation
Management PCL injury
Non-surgical treatment
- Isolated Grd 1-2
- Strengthening with ROM knee exercises
- Progressive return to sport after completing battery of test protocols
Surgery
- Failed conservative treatment for low grade PCL tear with instability
- Functional instability in a PCL deficient knee
- Multiligamentous knee injury with knee instability
Quadriceps muscle
Hamstring muscle
The antagonistic action of the hamstring and extensor muscle groups allow knee flexion and extension. The intact cruciate ligaments provide stability thereby preventing tibia translation. Rehabilitation include strengthening these muscle groups around the knee
PCL surgical principles
- Reconstruct the PCL with graft and attach it to its anatomic sites
- Graft selection: Allograft or autograft, single bundle or double bundle PCL reconstruction
Femur fixation
- Inside out or outside in technique
- Screw fixation or suspensory fixation (endobutton)
Tibia fixation
- Transtibial fixation
- Tibia inlay
Graft options
Graft features
PCL Femur graft attachment options
Single bundle
- Single bundle PCL the proximal-distal attachment location in the femur rather than the anterior-posterior location influences graft function.
- For a single bundle PCL recon: graft should be placed in AL or central position. Avoid PM position due to ↑ graft straining with ↑ the risk of failure.
- For single-bundle PCL: Anterior femoral tunnel position provides less posterior tibia translation than posterior tunnel position.
Double bundle
- For double-bundle PCL recon: anterior & posterior tunnel position also affects the degree of posterior tibia translation, with anterior position causing less posterior translation.
PCL Tibia graft fixation options
Transtibial fixation
Tibia inlay fixation
PCL Graft tensioning
- Graft tension at 90° knee flexion
- If associated LCL/PLC then fix and tension accordingly
- Post surgery: knee in protected brace in extension
Knee ROM brace allow setting of specific knee range of motion (ROM)
Hip extensor muscle strengthening with knee in extension using resistance band
Download ASSIC Performance Fingerprint or Strength & Conditioning apps for guideline PCL rehab routines
References
- Markolf KL, Feeley BT, Jackson SR, McAllister DR: Where should the femoral tunnel of a posterior cruciate ligament reconstruction be placed to best restore anteroposterior laxity and ligament forces? Am J Sports Med 2006; 34:604-611.
- Matava M J, Ellis E, Gruber B. Surgical Treatment of Posterior Cruciate Ligament Tears: An Evolving Technique. J Am Acad Orthop Surg 2009;17: 435-446.
- Mannor DA, Shearn JT, Grood ES, Noyes FR, Levy MS: Two-bundle posterior cruciate ligament reconstruction: An in vitro analysis of graft placement and tension. Am J Sports Med 2000;28:833-845.
- Eakin CL, Cannon WDJ. Arthrometric evaluation of posterior cruciate ligament injuries. Am J Sports Med. 1998;26:96-102.
- Petrie RS, Harner CD. Evaluation and management of the posterior cruciate injured knee. Oper Tech Sports Med. 1999;7:93-103.
- Harner CD, Baek GH, Vogrin TM, Carlin GJ, Kashwaguchi S, Woo SL: Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999; 15:741-749.
- Takahashi M, Matsubara T, Doi M, Suzuki D, Nagano A: Anatomical study of the femoral and tibial insertions of the anterolateral and posteromedial bundles of the human posterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14:1055-1059.
- Edwards A, Bull AM, Amis AA: The attachments of the fiber bundles of the posterior cruciate ligament: An anatomic study. Arthroscopy 2007;23:284-290.
