Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics

Abstract

The posterior cruciate ligament (PCL) represents an intra-articular structure composed of two distinct bundles. Considering the anterior and posterior meniscofemoral ligaments, a total of four ligamentous fibre bundles of the posterior knee complex act synergistically to restrain posterior and rotatory tibial loads. Injury mechanisms associated with high-energy trauma and accompanying injury patterns may complicate the diagnostic evaluation and accuracy. Therefore, a thorough and systematic diagnostic workup is necessary to assess the severity of the PCL injury and to initiate an appropriate treatment approach. Since structural damage to the PCL occurs in more than one third of trauma patients experiencing acute knee injury with hemarthrosis, background knowledge for management of PCL injuries is important. In Part 1 of the evidence-based update on management of primary and recurrent PCL injuries, the anatomical, biomechanical, and diagnostic principles are presented. This paper aims to convey the anatomical and biomechanical knowledge needed for accurate diagnosis to facilitate subsequent decision-making in the treatment of PCL injuries.Level of evidence V.

Keywords: Anatomy; Biomechanics; Diagnostic workup; Knee; PCL; Posterior cruciate ligament; Posterior stress radiograph; Revision.

Fig. 1

Schematic illustration of the anatomy of the posterior cruciate and the meniscofemoral ligaments. a Right knee from an antero-lateral view. b Right knee from a posterior view. ACL anterior cruciate ligament; ALB anterolateral bundle; aMFL anterior meniscofemoral ligament; LCL lateral collateral ligament; LM lateral meniscus; MCL medial collateral ligament; MM medial meniscus; PFL popliteofibular ligament; PMB posteromedial bundle; pMFL posterior meniscofemoral ligament; PT popliteus tendon

Fig. 2

Schematic illustration of the insertional zones of the posterior cruciate ligament in the right knee (posterior view). ALB anterolateral bundle; aMFL anterior meniscofemoral ligament; PMB posteromedial bundle; pMFL posterior meniscofemoral ligament

Fig. 3

Right knee from a posterior view demonstrating single-bundle vs. double-bundle posterior cruciate ligament reconstruction (PCL-R). a Transtibial single-bundle PCL-R. b Transtibial double-bundle PCL-R

Fig. 4

Sagittal T2-weighted magnetic resonance imaging scans of the posterior cruciate ligament (PCL). a Intact PCL. b Partial grade II PCL injury. Note the increased sagittal diameter of the PCL and the striated increased intraligamentary signal intensity. c Midsubstance grade III PCL injury. d Femoral grade III PCL injury. e Grade III tibial avulsion injury of the PCL. White arrow denotes injury site

Fig. 5

Posterior stress radiographs. Left, 8-mm posterior tibial translation (PTT) (a) and right, 18-mm PTT (b) quantified by lateral kneeling stress radiographs of a patient with failed posterior cruciate ligament reconstruction of the right knee. Posterior tibial translation is measured as the distance between line 2 and line 3 (yellow double-headed arrow). Line 1, tangential to the medial tibial plateau; Line 2, perpendicular to line 1 and crossing the midpoint between the posterior border of the medial and lateral tibial plateau; Line 3, parallel to line 2 crossing the midpoint between the medial and lateral femoral condyle