The Knee: Reconstruction, Replacement  and Revision Tracking Pixel
Duke Orthopaedics
presents
Wheeless' Textbook of Orthopaedics

Posterior Cruciate Ligament   


- Discussion:
    - anatomy of PCL:
    - function and natural history:
           - provides 95% of total restraining force to straight posterior translation of the tibia relative to femur;
           - secondary restraints to posterior displacement of the tibia include posterolateral capsule, popliteusMCL, and POL;
           - secondary action includes resistance to varus, valgus, and external rotation;
           - PCL is more verticle in extension and more horizontal in flexion;
           - hyperflexion mechanism: most common mechanism for an isolated PCL injury:
                  - hyperflexion causes the large anterolateral component to fail but spares the posteromedial band (which is loose in flexion);
                  - this type injury does not involve the secondary restraints and does well with non operative treatment;
                  - dashboard injury (from MVA): may result in severe combined injuries;
           - left untreated PCL ruptures may lead to chronic patello femoral as well as medial compartment arthrosis; 
           - references:
                  - Epidemiology of posterior cruciate ligament injuries. 
                  - Effect of Posterior Cruciate Ligament Deficiency on In Vivo Translation and Rotation of the Knee During Weightbearing Flexion
                  - A Clinically Relevant Assessment of Posterior Cruciate Ligament and Posterolateral Corner Injuries. Evaluation of Isolated and Combined Deficiency
    - associated injuries:
           - ACL and collateral ligament injury (knee dislocation);
           - when PCL injury occurs w/ MCL injury, expect large increase in valgus instability when the knee is in full extension;
           - tibial plateau rim fractures:
                  - when these occur with PCL injuries, there is often a severe combined ligament injury or dislocation;
           - posterolateral knee instability;
                  - it is important to distinguish this type of instability from one plane posterior instability;
                  - isolated PCL reconstruction will not correct the rotatory instability and will only partially correct the the one plane instability (since the tendency to externally
                             rotate results in relative shortening of PCL origin and insertion causing ligament laxity);
           - chondral injuries of the knee (when a dashboard injury is involved);


PCL Tears:

   - Examination of the PCL 
   - Radiographs:
        -
Accuracy of Stress Radiography Techniques in Grading Isolated and Combined Posterior Knee Injuries
        - Stress radiography for quantifying posterior cruciate ligament deficiency
   - MRI Findings:
        - references:
              - The accuracy of selective magnetic resonance imaging compared with the findings of arthroscopy of the knee.
              - Medial Segond-type fracture: cortical avulsion off the medial tibial plateau associated with tears of the posterior cruciate ligament and medial meniscus.

- Prognosis / Non Operative Treatment:
    - w/ isolated tear prognosis is generally considered to be favorable except for the long term possibility of patellofemoral arthrosis;
    - indications for non op treatment include chronic injury in older less active patients, or an isolated grade 2 injury (tibial surface flush w/ surface of femoral condyle;
    - remember that PCL tears from a hyperflexion mechanism will most commonly cause a tear of the larger anterolateral where as the posteromedial band remains
                  intact (which is loose in flexion);
                  - this type injury does not involve the secondary restraints and does well with non operative treatment;
    - references:
           - Natural history of the posterior cruciate ligament-deficient knee.
           - The cruciate ligaments of the knee. Anatomical, functional, and experimental analysis
           - Conservative treatment of isolated injuries to the posterior cruciate ligament in athletes.
           - Arthroscopic evaluation of articular cartilage lesions in posterior-cruciate-ligament-deficient knees.
           - Subjective results of nonoperatively treated, acute, isolated posterior cruciate ligament injuries
           - Biomechanical verification that PCL reconstruction is unnecessary in the muscle-stabilized knee.
           - In Vivo Analysis of the Isolated Posterior Cruciate Ligament–Deficient Knee During Functional Activities


- Operative Treatment of PCL Tear: 
    - indications for operative treatment: 
           - acute injuries; 
           - active young patient;
           - either isolated grade 3 tears (anterior border of tibia is posterior to femoral condyles) or
                    combined injury such as grade 2 injury (tibial surface and the femoral condyles are
                    flush) along with posterolateral instability;
    - treatment of avulsion frx 
    - PCL reconstruction


- References:

Current Concepts Review.  Injuries of the Posterior Cruciate Ligament.

Limits of movement in the human knee. Effect of sectioning the posterior cruciate ligament and posterolateral structures.

Posterior tibial subluxation of the posterior cruciate-deficient knee.

The effects of sectioning of the posterior cruciate ligament and the posterolateral complex on the articular contact pressures within the knee.

Long-term followup of posterior cruciate ligament rupture: a study of 116 cases.

Isolated posterior cruciate ligament injuries in athletes

 



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, April 9, 2012 12:02 pm