Background: Knee stability is affected by integrity of anterior cruciate ligament (ACL). Knee stiffness is a worrying postoperative complication, preventing patients from returning back to pre-injury sport level. In this study, we analyzed incidence of knee stiffness post ACL reconstruction and possible associated risk factors. Methods: This is retrospective study, was held in Royal Medical Services/Jordan–Queen Alia Military hospital/Arthroscopic and Sport injuries division. We analyzed 250 patients’ data using computerized patients record system (CPRS) called Hakeem complaining of knee stiffness post ACL reconstruction between July 2022 and July 2023, whom ACL reconstructive surgeries were performed between March and September 2022. Results: Incidence of knee stiffness post ACL reconstruction is about 1.5% (4 out of 250). All of those 4 patients were males,3 of them had limited flexion (75%), while 1 of them had limited extension (25%). All of the 3 patients having extension contracture had an associated medial meniscus tear, repaired at time of ACL reconstruction, while flexion contracture patient had an isolated ACL tear. Conclusions: Incidence of knee stiffness post ACL reconstruction is about 1.5%. 75% of patients were associated with medial meniscus tear, who underwent meniscus repair and hinged knee brace was applied. We conclude that ACL patients having an associated meniscus tear managed by meniscus repair and hinge knee brace are at higher risk to develop knee stiffness. Therefore, we recommend limiting the usage of knee brace for ACL reconstruction with meniscus repair only.