OBJECTIVE Objective of this study was to determine the relationship between development of stump entrapment (SE) lesions and associated injuries in patients with knee extension deficits who underwent anterior cruciate ligament (ACL) reconstruction surgery. METHODS This retrospective study included 79 patients who had an arthroscopy-proven ACL rupture causing knee extension loss. Presence and type of the SE lesions, injuries of collateral-cruciate ligaments and bones, and tears of the menisci were evaluated and recorded on magnetic resonance imaging. RESULTS The SE lesions were significantly more common in patients who had compressive posterior lateral tibial plateau fractures, tibia medial plateau edema and medial collateral ligament (MCL) injuries compared to the patients without stump lesions (p < 0.05). Posterior cruciate ligament (PCL) partial tears or sprains were significantly more common in patients with SE 1 lesions compared to the patients with SE 2 lesions (OR = 6.72; 95 % CI: 1.56-28.93). CONCLUSIONS SE is significantly more common in patients with compressive posterior lateral tibial plateau fractures, tibia medial plateau edemas and MCL injuries. PCL injury is more common in patients with type 1 SE.