A biomechanical analysis of joint contact forces in the posterior cruciate deficient knee

Abstract

The approach to the posterior cruciate deficient knee is controversial. The purpose of this study is to document the biomechanical changes in the static cadaveric knee model with simulated physiological loads. Nine fresh cadaveric knees from young donors (aged under 45 years) were mounted on a materials testing machine. Loading was carried out at 0 degrees, 30 degrees and 60 degrees to 1.5 kN with low-pressure sensitive Prescale film (Fuji; Tokyo, Japan) inserted through arthrotomies into the medial and lateral compartments. Computerized analysis of the imprints on the film was then carried out. Tests were then repeated after cutting the posterior cruciate ligament (PCL). Results demonstrate a statistically significant posterior subluxation of the tibia on the femur at 60 degrees flexion. This causes a significant increase in contact pressure and pressure concentration on the medial compartment of the knee after cutting the PCL. This may help explain the long-term degenerative changes observed in the medial femoral condyle after cutting the PCL.

Is the All-arthroscopic Tibial Inlay Double-bundle PCL Reconstruction a Viable Option in Multiligament Knee Injuries?

“…It is now generally accepted that patients with isolated PCL injuries with greater than 10 mm of posterior laxity or high-grade PCL injuries associated with multiligamentous knee injuries have improved subjective outcomes, side-to-side differences in stability, and decreased laxity on stress radiographs with operative intervention [5,11,13,23,25,36,39,45,47,54]. This may be the result of restoration of normal knee kinematics and a decreased propensity to develop medial compartment and patellofemoral compartment arthrosis [7,19,26,28,46,51]. Despite the demonstrated benefit of operative intervention, debate remains over the most advantageous operative technique.…”

A review of the anatomical, biomechanical and kinematic findings of posterior cruciate ligament injury with respect to non-operative management

“…The larger curvature radius of the medial femoral condyle means that with relative anterior subluxation of the femur; a higher pressure point with less congruence occurs at the tibiofemoral joint entrapping the anterior portion of the medial meniscus [49]. The pattern of the articular cartilage degeneration and meniscal injury correlates with the abnormal kinematics and contact pressures in the medial compartment of the PCL deficient knee demonstrated in cadaveric studies as outlined above [6,44].…”

“…One study reported a significant increase at 60 and 90°of flexion but no changes at 0 and 30°of flexion [6]. Another study reported a mean increase of 52% of medial compartment pressure regardless of flexion angle [44].…”

“…It consists of two components, the anterolateral and posteromedial bundle which demonstrate different strain rates at different degrees of knee flexion [4]. Cadaveric studies have also analysed the tensile strength [5], chondral deformation forces [6] and primary and secondary restraining functions of the PCL [7]. However, it is difficult to correlate the findings of cadaveric studies to clinical evaluation of the patient with a PCL injury because cadaveric studies cannot replicate the contribution to joint stability of surrounding neuromuscular structures.…”

The Clinical Problems of Ligament Healing of the Knee

“…19 Further, several studies have shown that PCL insufficiency leads to a significant increase in pressure to the medial compartment. 20,21 A most common mechanism of isolated PCL injury is the dashboard injury, either in trauma, when a flexed knee hit the dashboard, or in sports activities, when the knee hits the ground, pushing the tibia backwards. 22 Hyperflexion or hyperextension of the knee could also give rise to PCL injuries.…”