BACKGROUND: Several studies on the relationship between morphological parameters and posterior cruciate ligament (PCL) injury have already been conducted. However, few studies focused on the association between the morphology of the tibial ridge and PCL injury, especially in isolated PCL cases. PURPOSE: To retrospectively compare tibial ridge morphology between patients with isolated PCL tear and age/sex-matched controls with intact PCL after a knee injury. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: In a single center, 78 patients who were diagnosed with isolated PCL tears, confirmed by magnetic resonance imaging (MRI) or arthroscopy, were retrospectively analyzed. The control group consisted of 78 patients who had sustained knee trauma but showed no structural damage on MRI. MRI was used to measure the geometry of the tibial ridge, including the height of the medial tibial ridge (HMTR), the height of the lateral tibial ridge (HLTR), the width between ridges (WR), the slope length (SLPIR), the slope angle of the posterior intercondylar ridge, and the height of the posterior intercondylar ridge (HPIR). Tibial plateau was evaluated with the medial posterior tibial slope (MPTS), the lateral posterior tibial slope (LPTS), and the width of the tibial plateau (WTP). The mean values of these parameters were analyzed using a paired test, and binary logistic regression analyses were conducted. RESULTS: No significant differences were found in age, limb side, or body mass index between groups. Among all patients, those with isolated PCL ruptures demonstrated significantly greater HMTR (9.02 vs 8.12 mm; < .001), HLTR (8.32 vs 7.26 mm; < .001), HPIR (16.20 vs 15.56 mm; = .01), and SLPIR (21.71 vs 21.03 mm, = .015), along with a narrower WR (11.33 vs 12.58 mm; < .001), compared with the control group. Sex-specific analysis showed consistent trends in both male and female patients. In addition, male patients exhibited a smaller WTP (7.78 vs 7.92 cm; = .033) and a lower MPTS (6.86°vs 8.46°; = .008) compared with female patients. Binary logistic regression identified increased HMTR (hazard ratio [HR], 1.51; = .028) and HLTR (HR, 1.371; = .028) as risk factors, while narrower WR was protective (HR, 0.807; = .007). CONCLUSION: A high and narrower tibial ridge is associated with isolated PCL tears, compared with PCL-intact controls. In sex-stratified analyses, smaller tibial plateau width and reduced MPTS were observed in male patients with PCL compared with male controls, suggesting that the anatomic associations with PCL injury may differ between sexes.