PCL - POSTERIOR CRUCIATE LIGAMENT

 The Injury

• Origin: It passes backwards and downwards from the bottom of the femur (thigh bone)
• Insertion: to the top of the tibia (shin bone).
• Function: Its main purpose is to prevent the tibia slipping backwards on the femur.

• The injury can occur when an athlete falls to the ground on a bent knee, causing the upper tibia to strike the ground first. 
• A prominent tibial tubercle resulting from Osgood Schlatter's disease may enhance the impact when the tibia strikes the ground.

• One study estimates that PCL injuries make up as many as 20% of all knee ligament injuries, but the diagnosis is often missed. This is due to the fact that many people can function normally without a PCL. However, detection of PCL injury is important because untreated PCL ruptures will lead to significant degeneration (osteoarthritis) of the knee and disability in later life.

 Signs and Symptoms

• Unlike those with ACL injuries, patients who have PCL injuries do not usually experience much swelling or pain, and they report vague symptoms such as unsteadiness or insecurity of the knee. Patients who have chronic injuries may report pain around the kneecap.
• One of the most widely used tests is the posterior drawer test. It is done with the patient lying on their back, the knee bent to a right-angle, and the foot flat on the table. In this position, the tibial plateau should lie 1 cm in front of the femoral condyles. The degree of PCL injury is determined by the extent that the tibia can be pushed backwards by the examiner:
• No injury: The tibial plateau remains 1 cm in front of the femoral condyles.
• Grade 1: The tibial plateau moves backwards but stays in front of the femoral condyles.
• Grade 2: The tibial plateau moves backwards to lie level with the femoral condyles.
• Grade 3: The tibial plateau moves backwards to lie behind the femoral condyles.
• X-rays are useful to rule out avulsion fractures (where the PCL has been pulled away from one of its bony attachments). Magnetic Resonance Imaging (MRI) is useful in confirming the diagnosis. However, when the injury is chronic, an MRI may show an apparently normal PCL even though laxity may be present.

 Treatment

• Grade 1 or 2 PCL injuries should first receive non-operative treatment that includes aggressive quadriceps strengthening and full range-of-movement maintenance. Patients may return to sports when quadriceps and hamstring strength reaches 90% of the opposite side. This may take as long as 4-6 weeks.
• Follow this up every 2 years with x-rays and a bone scan, to monitor joint status. If early signs of degenerative joint disease appear on the bone scan, PCL reconstruction should be considered. Surgical treatment should also be considered if symptoms develop or if function declines.
• Grade 3 injuries should be treated with PCL reconstruction. Before surgery the patient should undertake rehabilitation to regain full range of motion and quadriceps strength.
• Avulsion fractures should be treated surgically.
• A PCL injury combined with significant ligament injuries should be treated with PCL reconstruction and repair of other injured structures.