Objective To investigate the effects of the patellar height and tilt angle on the long-term knee joint mobility after total knee arthroplasty (TKA). Methods Totally, 116 patients who underwent TKA without patellar replacement at Xuzhou Medical University Affiliated Hospital between January 2020 and December 2022 were included. Based on the recovery of the knee joint range of motion (ROM) within a year after surgery, the patients were divided into a normal knee ROM (knee ROM ≥ 120°) group (42 cases) and descending knee ROM (knee ROM<120°) group (74 cases). A year after the surgery, the patellar heights and tilt angles of the two groups of patients were compared. The recovery status of knee function and pain between the two groups of patients at the third month and first year after surgery were recorded. Results None of the 116 patients had nerve, vascular, or ligament injuries after surgery. Moreover, no patellar dislocation or infection occurred. The incision healed well in the first postoperative period. An year after surgery, the Insall-Salvati ratio of patellar height and patellar inclination of the patients in the normal group was lower than that of the patients in the descending group (P<0.05). Prior to surgery, at the third month and first year after surgery, the HSS scores of knee function increased gradually in both the patient groups. The HSS scores of the normal group were higher than those of the decreasing group (P<0.05), the knee pain scores of both the groups decreased gradually, and the pain scores of the normal group were lower than those of the decreasing group (P<0.05). The patellar height and inclination were risk factors for decreased knee ROM after TKA (P<0.05). Conclusions Patients who underwent TKA without patellar replacement experienced a decrease in knee ROM after surgery. This is associated with an increase in the patellar height and tilt angle.