Background: Missed diagnosis rate of spiral tibia shaft fracture with posterior malleolus crack fracture (PMCF) is high in the clinical. However, the mechanism and related factors of fracture are still unclear. Moreover, PMCF has been observed in other types of tibial shaft fractures. Objective: To explore the correlative factors of tibial shaft fracture with ipsilateral PMCF, decrease the rate of clinical missed diagnosis, strengthen the effective fixation of PMCF, and reduce the incidence of traumatic arthritis. Methods: From September 2014 to May 2019, we collected 137 tibiofibular fracture. Only 68 cases involved in ankle joint CT examination and were retrospectively analyzed. The patients were divided into posterior malleolus group (30 cases) and non-posterior malleolus group (38 cases) according to whether come up PMCF or not. The posterior malleolus group contained 24 males and 6 females, 27-77 (47.57±11.79) years old, the non-posterior malleolus group contained 23 males and 15 females, 18-85 (48.71±13.84) years old. The gender, age, location, fibula fracture and tibial shaft fracture classification were observed for univariate and multivariate analysis. Results: The probability of PMCF was higher with right tibial shaft fracture (OR=3.69 95%CI:1.13-12.08 P<0.05); the probability of PMCF following distal fibular fracture was higher than that without fibular fracture (OR=11.36 95%CI:1.72-75.05 P<0.05); the probability of PMCF with type A tibial shaft fracture was higher than type C (OR=4.8295%CI:1.19-19.58 P<0.05). Conclusion: Right type A tibial shaft fracture accompanied by distal fibular fracture are very important factors related to PMCF, which needs highly attention to avoid clinical missed diagnosis.