Arthroscopic Excision of Posterior Cruciate Ligament Cysts Using a Double Posteromedial Approach

Cruciate ligament knee cysts, particularly posterior ones, are uncommon. Arthroscopic surgery is the preferred treatment due to minimal trauma, low recurrence, and quick recovery, making it the most common choice for complete cyst removal. Posterior cruciate ligament cysts located behind the ligament are treated with a double posteromedial approach during arthroscopic surgery.

This approach in first developed visual for complete cyst removal, simplifying the procedure with minimal trauma, less recovery, and no recurrence. Our surgical approach is particularly suitable for the removal of cysts located on the dorsal side of the posterior cruciate ligament. The third approach is more advantageous if the set is compartmentalized or close to the tibial end.

To begin, use a blood-repellent belt to expel blood from the affected limb of the patient. Establish in anterior lateral approach 1 centimeter above the lateral knee line. Now establish an anterior medial approach 1 centimeter above the medial knee articular line.

Insert the arthroscope parallel to the tibial platform towards the intercondylar fossa in both approaches. To establish a normal posterior medial approach, first flex the knee at a 90-degree angle, then insert the arthroscope in the anterior medial approach to monitor the intercondylar fossa. Place a switching rod in the anterior lateral approach.

Next, insert exchange rod between the posterior cruciate ligament and the medial femoral condyle into the posterior medial joint capsule. Slowly rotate the lens to observe the triangular area formed by the reverse fold of the capsule, condyle and medial meniscus. Turn off the operating room lights.

Observe the translucent area of the posterior medial skin surface of the knee. With a lumbar needle, puncture the area to assist positioning. Then with an 11-gauge sharp blade, make a 0.5-centimeter-long incision in the skin.

Insert a straight clamp into the joint capsule and establish a normal posterior medial approach. For the establishment of a high posterior medial approach, insert the arthroscope into the posterior medial approach. Then insert a lumbar needle in the direction of the joint.

Now penetrate the joint capsule with the needle into the triangular space between the medial posterior condyle meniscus and posterior joint capsule. Make a small incision on the skin. Then insert a straight clamp into the joint capsule to establish the high approach.

With the arthroscope in the high posterior medial approach, insert the shaver into the normal posterior medial approach. Now remove the synovial tissue between the posterior cruciate ligament and the joint capsule. Locate the translucent cyst around the ligament and remove the cyst wall to view the compartment-like tissue inside it.

Excise the posterior cyst completely. Now insert the arthroscope into the anterior lateral approach. A portion of the cyst at the femoral terminus of the ligament will be visible.

Remove the anterior cyst wall to see yellow translucent fluid flow out of the cyst. Then remove the cyst wall completely. Probe the posterior cruciate ligament to check for any damage.

Then insert the arthroscope into the medial patellar approach. Check the V-shaped space between the anterior and posterior ligaments for residual cysts. To close the incision, insert an arthroscopic sheath into the anterior lateral approach.

Squeeze the suprapatellar capsule to completely drain the intraarticular fluid. Check the knee extension inflection from 0 to 120 degrees. Then suture the incision shut with a number 4 silk thread.

For postoperative rehabilitation, ask the patient to perform the quadriceps exercise in the supine position. Let the patient straighten the affected limb, hook up the toes, and slowly lift the leg about 15 centimeters on the heel. Let the patient keep the leg up at this height for three seconds before lowering the leg down.

Additionally, the patient can perform joint release trading at their bedside by knee joint extension and flexion. All eight patients shared the symptoms of knee hyperflexion pain, inability to squat freely, and pain in the knee. Surgery relieved all patients of these common symptoms.

Posterior cruciate ligament cysts were seen on preoperative MRI in all patients. The cyst wall was completely removed during surgery. All patients had an MRI one year after surgery and no recurrence was found.