PurposeTo analyze the effect of percutaneous pie-crusting medial release on valgus laxity before and after surgery and on clinical outcomes.MethodsEight-hundred fourteen consecutive patients who underwent an arthroscopic procedure for the medial compartment of the knee were evaluated retrospectively. Sex, age, type of operation (meniscectomy, meniscal repair, and posterior root repair), type of accompanying surgery (none, cartilage procedure, ligament procedure and osteotomy) were documented. Sixty-four patients who underwent percutaneous pie-crusting medial release (release group) and 64 who did not undergo medial release (non-release group) were matched using the propensity score method. Each patient was evaluated for the following variables: degree of valgus laxity on stress radiographs, Lysholm knee score, visual analog scale score, and International Knee Documentation Committee knee score and grade.ResultsAt the 24-month follow-up, no significant increase in side-to-side differences in the valgus gap was observed in comparison to the preoperative value in the release group [preoperative, − 0.1 ± 1.3 mm; follow-up, − 0.1 ± 1.4 mm; (n.s.)]. The follow-up Lysholm score, visual analog scale score and International Knee Documentation Committee knee score and grade were similar between the two groups.ConclusionsPercutaneous pie-crusting medial release is an additional procedure that can be performed during arthroscopic surgery for patients with a narrow medial joint space of the knee. Percutaneous pie-crusting medial release reduces iatrogenic injury to the cartilage and does not produce any residual valgus laxity of the knee.Level of evidenceIV.