IntroductionLateral patellar compression syndrome is one of the causes of anterior knee pain in young adults and resulted from tight lateral patellar retinaculum. The aim of our study is to compare between open and arthroscopic release of lateral patellar compression syndrome in relation of functional outcome, time of surgical procedure, length of hospital stays, intraoperative and postoperative complications as bleeding, infection, recurrence, and patellar instability with 2 years of follow-up.Materials and methods80 patients, age (21–49 years), were divided randomly into 2 groups (A and B). Group A (40 patients) were treated with open release. Group B (40 patients) were treated by arthroscopic release. All these patients are diagnosed as lateral patellar compression syndrome depending on clinical features and MRI. All patients were assessed by Lysholm knee scoring scale before surgery and at periods of 2, 6 weeks, 6, 12, and 24 months after surgery.ResultsThere is significant difference in functional outcome, measured by Lysholm knee scoring scale, between preoperative and postoperative assessment periods in both groups (P < 0.001). There is significantly better functional outcome at 2 years of follow-up with arthroscopic release (P = 0.018). There is no recurrence in both groups, but there were 4 patients develop medial patellar instability in the group of open release.ConclusionBoth open and arthroscopic lateral release for patients with isolated lateral patellar compression syndrome can be effective surgical procedures, but arthroscopic release can achieve better functional outcome.Trial registration: NCT, NCT04130412. Retrospectively registered on 3rd of June, 2020 at ClinicalTrials.gov.