Objective To compare the effects of straight incision and transverse S-shaped incision on scar formation and joint function after patellar fracture surgery. Methods A total of 70 patients with patellar fracture diagnosed and treated in our hospital from April 2022 to April 2023 were selected as the research objects. They were divided into control group and observation group by random number table method, with 35 patients in each group. The control group was treated with transverse incision, and the observation group was treated with straight incision. The clinical operation indexes, complication rate, scar VSS score and joint function Bostman score were compared between the two groups. Results The incision length of the observation group was less than that of the control group, the intraoperative blood loss was less than that of the control group, and the fracture healing time was shorter than that of the control group (P <0.05). The incidence of complications in the observation group (8.57%) was lower than that in the control group (20.00%) (P <0.05). After 12 weeks of treatment, the scores of scar dimensions (vascular distribution, softness, color, thickness) in the observation group were lower than those in the control group (P <0.05). The Bostman score of the observation group was higher than that of the control group at 12 and 24 weeks of treatment (P <0.05). Conclusion Compared with the transverse S-shaped incision, the straight incision in the treatment of patellar fracture has the advantages of small incision, less intraoperative blood loss, conducive to fracture healing, small postoperative scar formation, and good recovery of joint function.However, the transverse S-shaped incision is relatively well exposed, and the clinical choice can be made according to the specific situation of the patient's patellar fracture.