Posterior Cruciate Ligament: Current Concepts Review

Abstract

The posterior cruciate ligament (PCL) is the largest and strongest ligament in the human knee, and the primary posterior stabilizer. Recent anatomy and biomechanical studies have provided an improved understanding of PCL function. PCL injuries are typically combined with other ligamentous, meniscal and chondral injuries. Stress radiography has become an important and validated objective measure in surgical decision making and post-operative assessment. Isolated grade I or II PCL injuries can usually be treated non-operatively. However, when acute grade III PCL ruptures occur together with other ligamentous injury and/or repairable meniscal body/root tears, surgery is indicated. Anatomic single-bundle PCL reconstruction (SB-PCLR) typically restores the larger anterolateral bundle (ALB) and represents the most commonly performed procedure. Unfortunately, residual posterior and rotational tibial instability after SB-PCLR has led to the development of an anatomic double-bundle (DB) PCLR to restore the native PCL footprint and co-dominant behavior of the anterolateral and posteromedial bundles and re-establish normal knee kinematics. The purpose of this article is to review the pertinent details regarding PCL anatomy, biomechanics, injury diagnosis and treatment options, with a focus on arthroscopically assisted DB-PCLR. Level of evidence: IV.

Keywords: double bundle posterior cruciate ligament reconstruction; posterior cruciate ligament; posterior knee laxity; stress radiographs.

Figure 1

(A) Anterior and (B) posterior views of the native posterior cruciate ligament (PCL). Emphasized are the femoral and tibial attachments of the anterolateral bundle (ALB) and posteromedial bundle (PMB) of the PCL and the osseous landmarks: the trochlear point, the medial arch point, the bundle ridge, and the champagne-glass drop-off. ACL, anterior cruciate ligament; aMFL, anterior meniscofemoral ligament (ligament of Humphrey); FCL, fibular collateral ligament; PFL, popliteofibular ligament; pMFL, posterior meniscofemoral ligament (ligament of Wrisberg); POL, posterior oblique ligament (Reproduced with permission from Kennedy NI, Wijdicks CA, Goldsmith MT, et al. Kinematic analysis of the posterior cruciate ligament, part 1: the individual and collective function of the anterolateral and posteromedial bundles. Am J Sports Med. 2013;41(12):2828-2838.).

Figure 2

Lateral kneeling posterior stress radiographs that demonstrate an increase of 11.6 mm of posterior translation between the injured and uninjured knee. A line is extended parallel from the posterior cortex from at least 15 cm distal to the joint line. A perpendicular line is drawn from this line to the posterior point of the Blumensaat line and the distance is measured and recorded for each knee. The difference between these two points is the posterior tibial translation distance. (“Jackman T, LaPrade RF, Pontinen T, Lender PA. Intraobserver and interobserver reliability of the kneeling technique of stress radiography for the evaluation of posterior knee laxity. Am J Sports Med. 2008;36:1571-1776.”

Figure 3

Examination under anesthesia. On the left, a posterior sag is observed. On the right, an anterior drawer is performed to reduce the posterior tibial subluxation.

Figure 4

(A) Posterior and (B) anterior illustrations of the anatomic double-bundle, posterior cruciate ligament reconstruction. ACL, anterior cruciate ligament; aMFL, anterior meniscofemoral ligament (ligament of Humphrey); FCL, fibular collateral ligament; PFL, popliteofibular ligament; pMFL, posterior meniscofemoral ligament (ligament of Wrisberg); POL, posterior oblique ligament (Reproduced with permission from “Wijdicks CA, Kennedy NI, Goldsmith MT, et al. Kinematic analysis of the posterior cruciate ligament, part 2: a comparison of anatomic single- versus double-bundle reconstruction. Am J Sports Med. 2013;41(12):2839-2948”.).

Figure 5

Fluoroscopic image of transtibial tunnel guide pin placement. On the left, the lateral view shows the guide pin successfully positioned approximately 6 to 7 mm proximal to the champagne-glass drop-off at the PCL facet. On the right, the AP view shows appropriate position of the guidewire at the medial aspect of the lateral tibial eminence and 1 to 2 mm distal to the joint line.

Figure 6

Illustration depicting the intimate relationship of the posterior meniscal roots with the posterior cruciate ligament (PCL) (right knee). LPRA, lateral meniscal posterior root attachment; MPRA, medial meniscal posterior root attachment; SWF, shiny white fibers. Reproduced with permission from “Johannsen AM, Civitarese DM, Padalecki JR, Goldsmith MT, Wijdicks CA, LaPrade RF. Qualitative and quantitative anatomic analysis of the posterior root attachments of the medial and lateral menisci. Am J Sports Med. 2012;40(10):2342-2347”.