Arthroscopic treatment of popliteal cyst

Objective To evaluate the clinical effect of arthroscopic treatment of popliteal cyst. Methods Data of 42 patients, who had undergone arthroscopic treatment for popliteal cyst from November 2005 to January 2010, were retrospectively analyzed. There were 13 males and 29 females, including 6 children, aged from 11 to 68 years （average, 43.2 years）. All popliteal cysts were unilateral, including 14 cases of right knee and 28 cases of left knee. Eleven patients had recurrent popliteal cyst, and all of them underwent initial open surgery, and the duration from the initial surgery to recurrence ranged from 6 to 35 months （average, 18 months）. According to the Rauschning and Lindgren classification, there were 3 cases of grade I, 18 cases of grade II and 21 cases of grade III. Based on the MRI, the long diameter of the popliteal cysts ranged from 4.2 to 7.9 cm （average, 5.4 cm）, the transverse diameter 2.1 to 2.5 cm （average, 2.3 cm） and anteroposterior diameter 1.6 to 2.2 cm （average, 2.0 cm）. All popliteal cysts were at posteriomedial parts of the knees, and 11 cases of popliteal cyst communicated with the knee joint cavity. Before operation, 1 to 2 ml methylene blue was injected into the cyst, which was used to determine the channel intraoperatively ac- cording to the site where methylene blue flowed out. The intraarticular diseases were thoroughly treated when the inner wall of the popliteal cyst was cleaned. Results The intraarticular diseases were found in all patients intraoperatively, including medial meniscus tear in 28 cases, lateral meniscus tear in 9 cases and lateral discoid meniscus in 4 cases. There were no blood vessel complications, nerve complications and incision complications. All patients were discharged 2 or 3 days postoperatively. All patients were followed up for 10 to 30 months （average, 18 months）. No recurrence of popliteal cyst occurred at final follow-up. According to the Rauschning and Lindgren classification, there were 38 cases of grade 0 and 4 cases of grade I. Conclusion The arthroscopic treatment of popliteal cyst has several advantages, such as mini-invasion, fast recovery and low recurrence rate. Key words: Popliteal cyst;  Arthroscopy;  knee joint