Objective To investigate the impact of patellar height and tilt angle on long-term knee joint activity after total knee arthroplasty without patellar replacement. Methods A total of 116 patients who underwent total knee arthroplasty without patellar replacement at Xuzhou Medical University Affiliated Hospital from January 2020 to December 2022 were included. Preoperatively, based on the Insall-Salvati ratio, the study subjects were divided into a high patellar position group (n=28, Insall-Salvati ratio > 1.2) and a normal patellar height group (n=88, 0.8 ≤ Insall-Salvati ratio ≤ 1.2). Immediately postoperatively, patients were classified into a mild tilt group (n=80, patellar tilt angle < 5°) and a moderate-severe tilt group (n=36, patellar tilt angle ≥ 5°) based on their patellar tilt angle. The surgical progress, intraoperative nerve/vascular/ligament injuries, postoperative patellar dislocation/infection/fracture, and incision healing were recorded. At 3 months and 1 year postoperatively, the knee joint function, degree of knee joint pain, and range of knee joint motion were compared among different patellar height groups and different patellar tilt groups. Results The surgery progressed smoothly in all 116 cases, with no intraoperative nerve/vascular/ligament injuries or postoperative complications such as patellar dislocation/infection/fracture. The incisions healed primarily. At 3 months and 1 year postoperatively, the knee joint function scores and range of motion were lower in the high patellar position group compared to the normal patellar height group (P < 0.05), while the pain scores were higher (P < 0.05). The knee joint function scores and range of motion gradually increased (P < 0.05), while the pain scores gradually decreased (P < 0.05) in different patellar height groups preoperatively, at 3 months, and at 1 year postoperatively. At 3 months and 1 year postoperatively, the knee joint function scores and range of motion were lower in the moderate-severe tilt group compared to the mild tilt group (P < 0.05), while the pain scores were higher (P < 0.05). The knee joint function scores and range of motion gradually increased (P < 0.05), while the pain scores gradually decreased (P < 0.05) in different patellar tilt groups preoperatively, at 3 months, and at 1 year postoperatively. Patellar height (OR=5.523, 95% CI: 1.942-15.708) and patellar inclination (OR=5.124, 95% CI: 1.802-14.573) are risk factors for decreased knee joint mobility after total knee arthroplasty (P < 0.05). Conclusion In patients undergoing total knee arthroplasty without patellar replacement, an increase in preoperative patellar height and an increase in postoperative patellar tilt angle can both lead to a decrease in postoperative knee joint range of motion.