PCL

1. Anatomy and function of the posterior cruciate ligament (PCL)
: Located within the knee joint, connecting the medial condyle of the femur to the posterior tibial plateau, crossing the anterior cruciate ligament (ACL in a " " shape, it is an important stabilizing structure of the knee joint.
Function:
Restricts the tibia from displacing posteriorly ( function), preventing excessive extension and rotation of the knee joint.
Maintains knee stability together with the ACL, collateral ligaments, and menisci, especially significant when the is flexed (e.g., squatting, going up and down stairs).
2. Common causes and grading of PCL injuries
1. Causes of
Acute injury:
Hyperextension of the knee joint (e.g., hitting the front of the shin), posterior displacement of the tibia the knee is flexed (e.g., knee hitting the dashboard in a car accident).
Sports injuries (e.g., twisting or impact during soccer,, skiing).
Chronic injury: Long-term repeated excessive load on the knee joint, leading to gradual laxity or tear of the ligament.
2.ing of injuries (based on the degree of laxity)
Grade I: Mild ligament injury, normal length, tibial posterior displacement < 5mm
Grade II: Partial tear of the ligament, moderate laxity, tibial posterior displacement 5-10mm.
Grade III: Complete tear the ligament, severe laxity, tibial posterior displacement > 10mm, accompanied by knee joint instability.
3. Clinical manifestations and diagnosis of PC injuries
1. Symptoms
Acute phase: Swelling and pain in the knee joint (especially when flexing the knee), limited mobility, and some patients may hear "tearing sound."
Chronic phase:
Knee joint instability (e.g., "giving way," tripping easily when going up and down stairs.
Long-term can lead to meniscus injuries, cartilage wear, and even develop into osteoarthritis.
2. Physical signs
Posterior drawer: With the knee flexed at 90°, the examiner holds the proximal part of the patient's lower leg with both hands and pulls it posteriorly. If the tibia's posterior displacement increases significantly, it suggests a PCL injury.
Stair sign: When the knee is flexed at 90°, the tibial plateau is significantly "depressed" compared to the opposite side, which is a typical physical sign of a complete PCL tear.
3. Imaging examination
Xray: Can rule out fractures, but shows poor display of ligament injuries.
MRI: Gold standard, can clearly show the morphology of the PCL, the degree of, and combined injuries (such as meniscus tear, bone contusion).
4. Treatment principles for PCL injuries
Treatment goals: Restore knee joint stability relieve symptoms, and prevent long-term complications.
1. Conservative treatment (suitable for grade I-II injuries)
Acute phase: Rest, ice compress (to swelling), pressure dressing, elevation of the affected limb, and avoid bearing weight on the flexed knee.
Rehabilitation training:
Quadriceps strengthening (e.., straight leg raise, static squat against the wall), to enhance knee stability.
Balance training (e.g., single-leg standing), to improve propriception.
Avoid strenuous exercise (e.g., soccer, basketball), to reduce knee joint load.
Brace fixation: Wearing a knee to limit tibial posterior displacement and assist in rehabilitation.
2. Surgical treatment (suitable for grade III injuries or those ineffective with conservative treatment)
Surgical approach
PCL reconstruction surgery: Rebuilding the damaged PCL through grafted tendons (such as hamstrings, Achilles tendon), restoring its tension and stability.
 of combined injuries: If there are concurrent meniscus tears, cartilage injuries, it is necessary to perform repair or shaping surgery at the same time.
Postoperative rehabilitation
Early stage: Brace fixation (with the knee flexed at 30°), to perform passive movement and quadriceps training.
Mid-term