Arthroscopic internal drainage of popliteal cysts using the figure-of four position: a retrospective case series

Purpose This study aimed to evaluate the efficacy and safety of arthroscopic internal drainage for popliteal cysts using the figure-of-four position. Methods Between January 2016 and June 2024, 61 patients with symptomatic popliteal cysts underwent arthroscopic internal drainage with the knee positioned in a figure-of-four, while intra-articular lesions were managed with synovial debridement, meniscal repair/formation, and removal of loose bodies. Preoperative magnetic resonance imaging confirmed the presence of popliteal cysts and concomitant intra-articular lesions. Operation time and intraoperative blood loss were recorded. Patient satisfaction was evaluated by Rauschning-Lindgren (R-L) grade, Lysholm scale, visual analogue scale (VAS) score preoperatively and postoperatively, and popliteal cyst recurrence. Results All patients underwent successful surgery without major vascular and nerve injury. The average operation time was 66.1 ± 9.0 min. The average intraoperative blood loss was 8.34 ± 1.82 ml. All patients were followed up for an average of 13.46 months (5–24 months). No knee joint infection, lower extremity thrombosis, or neurovascular bundle injury were found during follow-up. The VAS score decreased from 5.54 ± 1.19 points preoperatively to 2.75 ± 0.77 points at 1 month postoperatively ( P < 0.05). The Lysholm knee score improved from 62.71 ± 4.22 points preoperatively to 89.70 ± 2.66 points at 6 months postoperatively ( P < 0.05). The R-L grade of popliteal cyst symptoms showed significant improvement at 6 months postoperatively compared to the preoperative assessment ( P < 0.05). Postoperative recurrence of popliteal cysts occurred in five cases without any symptoms (R-L grade 0), and the cyst volume did not increase significantly during follow-up. Conclusion Arthroscopic internal drainage of popliteal cysts using the figure-of-four position is a technically feasible and safe procedure that resulted in significant clinical improvement and a low rate of asymptomatic recurrence at short-to-mid-term follow-up. The figure-of-four position appears to be a useful technical adjunct for improving access and working space in the posteromedial compartment, and warrants further investigation.