We present a surgical approach to treat posterior cruciate ligament cysts by an arthroscopic double posteromedial approach.
Cruciate ligament cysts of the knee are a rare condition. Posterior cruciate ligament cysts of the knee are less common than anterior cruciate ligament cysts. In patients with asymptomatic isolated cruciate ligament cysts of the knee, conservative treatment is recommended. Symptomatic cruciate ligament cysts of the knee are mostly manifested as knee hyperflexion pain, straightening pain, knee discomfort after standing for a long time or walking for a long time, etc., which seriously affects the quality of life, surgical treatment can be performed. The surgical treatments can be divided into ultrasound-guided cyst puncture and fluid extraction procedure and arthroscopic cystectomy. Cysts are mostly lobulated with a multi-layer cyst wall, cyst fluid extraction does not remove the cyst wall completely but simply extracts cyst fluid, leading to a high recurrence rate. Arthroscopic surgery can completely remove the cyst wall with little trauma, a low recurrence rate, and fast postoperative recovery, so arthroscopic resection is the most common and preferred method of treatment. Since posterior cruciate ligament cysts mostly occur posterior to the ligament, we remove the cyst wall by adding a double posteromedial approach to the knee joint, and the cyst wall is removed under direct vision, which is simple to operate, the cyst wall is completely cleared, the trauma is small, the postoperative recovery is fast, and there is no recurrence. Here, 8 posterior cruciate ligament cysts were removed with complete postoperative symptom relief, no surgical complications, and no recurrence at 1-year follow-up.
Joint cysts are cystic lesions, and the cyst fluid is a transparent jelly-like fluid that can be found in the ligament, meniscus, synovial membrane, and other parts of the knee joint1,2. High mechanical stress can easily lead to cyst formation, which is why cysts are most common in the knee joint3,4, and Baker's cysts are the most common type of cysts5. Cruciate ligament cysts of the knee are rare, occurring incidentally in 0.2% to 1.3% of cases scanned using knee magnetic resonance imaging (MRI) and in 0.6% of patients tested using knee arthroscopy6,7. Posterior cruciate ligament cysts are rarer, with Brown and Dandy reporting that after performing knee arthroscopy on 6,500 patients, they found only 35 ligament cysts and only 6 from the posterior cruciate ligament5. Knee ligament cysts can occur regardless of sex or age but are more common in men aged 20 years to 40 years4,8.
The cause of cruciate ligament cysts is unknown. For the non-invasive diagnosis of knee ligament cysts, MRI can clearly show the relationship between the size and position of the cyst and is the most accurate diagnostic method4,6,9,10. Arthroscopic removal of cysts is the most effective and recommended treatment method4,6,9,10. Arthroscopy can see the cyst site directly and completely remove the cyst wall, the recurrence rate is extremely low, and the patient recovers quickly after surgery7,9,10. Posterior cruciate ligament cysts are mostly lobulated or multiloculated, most of which are located mainly behind the posterior cruciate ligament, and in 12.5% of patients, the cyst is mainly located anterior to the posterior cruciate ligament11 (Figure 1A,B).
Many treatments can be used to treat posterior cruciate ligament cysts, such as ultrasound and computed tomography-guided joint paracentesis. However, several studies have shown that there is a potentially higher risk of recurrence because of which these procedures do not remove the cyst walls12. Arthroscopic removal of cysts is the gold standard for the treatment of posterior cruciate ligament cysts. Arthroscopic surgery can completely remove the cyst wall, but it's hard to remove dorsal cruciate ligament cysts by the anterior approach alone. Abreu et al.12 introduced an approach to the arthroscopic excision of PCL cysts using a trans-septal portal, and it's safe and effective. Tsai et al.13 reported that the trans-septal approach to the resection of posterior cruciate ligament cysts was successful in 15 patients, and there was no recurrence. The trans-septal approach requires the addition of a posterolateral approach, so it increases the risk of damaging the common peroneal nerve and popliteal neurovascular bundle. To avoid these risks, we present a surgical approach to treat posterior cruciate ligament cysts by an arthroscopic double posteromedial approach. Our approach does not require an additional posterolateral approach; there is no risk of injuring the common peroneal nerve. We use the double posteromedial approach, which keeps the entire surgical process on the medial side of the posterior septal, thus reducing the possibility of damaging the popliteal neurovascular bundle. The technique produces the same results while being safer than the trans-septal approach. This surgical approach is particularly suitable for the removal of cysts located on the dorsal side of the posterior cruciate ligament. The surgical approach is more advantageous if the cyst is compartmentalized or close to the tibial end.
Posterior cruciate ligament cyst is a rare disease. Knee ligament cysts are usually discovered during MRI or knee arthroscopy exams. The causes of knee ligament cyst formation are varied, including post-traumatic formation, synovial tissue hernia formation during embryogenesis, and mesenchymal stem cell proliferation and formation. Recently, trauma and tissue stimulation have been recognized by most experts2,7,14.
<p class="…The authors have nothing to disclose.
This research was supported by the Youth Science and Technology Project of the Department of Health of Hebei Province. (No.20201046).
Arthroscopic sheath | smith&nephew | 72200829 | 6mm |
Arthroscopy | smith&nephew | 72202087 | 30 mm x 4 mm |
Beam guide | smith&nephew | 72204925 | 5 mm x 3.6 m |
Beam guide-arthroscopy end connector | smith&nephew | 2143 | |
Beam guide-panel connector | smith&nephew | 2147 | |
Blood-repellent belt | selani | tpe15100 | 15 cm x 1 m |
Blunt puncture cone | smith&nephew | 4356 | 4 mm |
Camera | smith&nephew | 72200561 | NTSC/PAL |
Coupler | smith&nephew | 72200315 | |
DYONICS POWER II | smith&nephew | 72200873 | 100-24VAC, 50/60Hz |
DYONICS POWERMAX ELITE | smith&nephew | 72200616 | |
Endoscopic camera system | smith&nephew | 72201919 | 560P NTSC/PAL |
HD monitor | smith&nephew | LB500031 | 27 inch |
Hook probe | smith&nephew | 3312 | |
Incisor plus platinum shaver | smith&nephew | 72202531 | 4.5 mm |
Lumbar needle AN-E/S ![]() |
tuoren | AN-E/S ![]() |
1.6 mm x 80 mm |
Micropunch,teardrop,left | smith&nephew | 7207602 | |
Micropunch,teardrop,right | smith&nephew | 7207601 | |
Micropunch,teardrop,straight | smith&nephew | 7207600 | |
Pitbull Jr. Grasper | smith&nephew | 14845 |