Arthroscopic Internal Drainage with Cyst Wall Resection and Arthroscopic Internal Drainage with Cyst Wall Preservation to Treat Unicameral Popliteal Cysts: A Retrospective Case–Control Study

OBJECTIVE: To compare the clinical efficacy and safety of arthroscopic internal drainage for the treatment of unicameral popliteal cysts with or without cyst wall resection. METHODS: This was a retrospective case–control study of 73 patients diagnosed with unicameral popliteal cysts from January 2012 to January 2019 who received arthroscopic treatment. The study included 38 cases with cyst wall resection (CWR group) and 35 cases with cyst wall preservation (CWP group). The CWR group consisted of 14 men and 24 women with an average age of 51.8 years, while the CWP group consisted of 13 men and 22 women with an average age of 52.0 years. All patients were examined for intra‐articular lesions and communicating ports by magnetic resonance imaging (MRI) prior to surgery, and recurrence of cysts was evaluated at the last follow‐up examination. Rauschning and Lindgren grade (R–L grade) and Lysholm score were used to evaluate clinical outcomes. In addition, operation time and complications were recorded. RESULTS: The average length of follow‐up was 24.2 months (range, 16 to 32 months). There were no considerable differences in age, gender, cyst size, Lysholm score, R–L grade and concomitant intra‐articular cases between the CWR group and CWP group prior to surgery (P > 0.05). The last follow‐up MRI scans showed that in the CWR group, the cyst disappeared in 25 cases and shrunk in 13 cases. In the CWP group, the cyst disappeared in 22 cases, shrunk in 12 cases and persisted in one case. There was no obvious difference in recurrence rate between the two groups (0% vs 2.9%, P = 0.899). At the last follow‐up, there were no differences in the R–L grade (P = 0.630) and Lysholm score (88.3 ± 5.6 points vs 90.1 ± 3.8 points, P = 0.071) between the two groups. Compared with the CWP group, operation time was significantly prolonged in the CWR group (38.3 ± 3.1 min vs 58.3 ± 4.4 min, P < 0.05). In the CWR group, three cases occurred fluid infiltration under the gastrocnemius muscle, which improved after pressure bandaging and cold compress. In another three cases, hematoma was found. The incidence of complications in the CWR group was markedly higher than that in the CWP group (15.8% vs 0%, P < 0.05). During the follow‐up period, none of the patients developed serious complications such as neurovascular injury, deep venous thrombosis, or infection. CONCLUSION: For unicameral popliteal cysts, arthroscopic internal drainage combined with resection of the cyst wall did not further improve the clinical outcomes or reduce the recurrence rate, while prolonging the operation time and increasing the possibility of complications.