Background: Fractures of the knee account for about 6% of all trauma admissions. While its management is mostly focused on fracture treatment, it is not the only factor that defines the final outcome. Objectives: This study aimed to study objective and subjective outcomes after proximal tibial versus distal femoral fractures in terms of knee instability and health-related quality of life. Patients and Methods: This retrospective, cross-sectional, cohort study was carried out on 80 patients with either isolated proximal tibial (n = 42) or distal femoral (n = 38) fractures, who underwent open reduction and internal fixation. All the fractures were classified based on the Schatzker and AO classification for tibial plateau and distal femoral fractures, respectively. The patients were followed and examined by an orthopedic knee surgeon for clinical assessment of knee instability. In their last follow-up visit, these patients completed a Lysholm knee score and the short-form (SF) 36 health survey. Results: Among the 42 tibial plateau fractures, 25% were classified as Schatzker type 2. Of the 38 distal femoral fractures, we did not find any type B1 or B3 fractures. The overall prevalence of anterior and posterior instability was 42% and 20%, respectively. Medial Collateral Ligament (MCL) and Lateral Collateral Ligament (LCL) injuries were detected clinically in 50% and 28%, respectively. The incidence rates of ligament injuries in tibial plateau fractures were as follows: Anterior Collateral Ligament (ACL) 26%, Posterior Collateral Ligament (PCL) 7%, MCL 24%, and LCL 14%. Medial collateral ligament injury was the most common in the Schatzker type 2 (50% of the injuries). Distal femoral fractures were associated with ACL injury in 16%, PCL in 13%, MCL in 26% and LCL in 14%. However, final knee range of motion (ROM) and function (Lysholm score) were not associated with fracture location. No statistically significant difference was observed between the two groups, except for the valgus stress test at 30°knee flexion, which was more positive in tibial fractures. All eight domains of SF-36 score in the distal femoral and proximal tibial fractures were significantly different from the normal values; however, there were no statistically significant differences between femoral and tibial fracture scores. Conclusions: Although ROM is acceptable in knee joint fractures, instability is common. However, it seems that knee function and quality of life are not associated with the location of the fracture