Abstract: Objective To explore the risk factors of joint stiffness after rotator cuff suture and construct a prediction model based on anatomical indicators. Methods 227 patients who underwent rotator cuff suture in our hospital from January 2018 to January 2024 were retrospectively included and were divided into the stiffness group (47 cases) and the non-stiffness group (180 cases) based on whether joint stiffness occurred 6 months after surgery or not.Use single factor and multi factor methods to analyze independent risk factors for joint stiffness after rotator cuff suturing surgery.Construct corresponding prediction models for predictive performance analysis. Results Compared with the non-stiff group (24.44%,0.71±0.02,and 75.09±5.95° respectively),the stiff group showed statistically significant differences in the preoperative shoulder joint stiffness rate (74.47%),postoperative acromial index (0.73±0.02),and postoperative lateral acromial angle (68.94±5.37)°,with all P-values less than 0.05.Multivariate analysis revealed that preoperative shoulder joint stiffness (OR=0.107,95%CI 0.045~0.256),a higher postoperative acromial index (OR=7.064,95%CI 4.764~10.475),and a smaller postoperative lateral acromial angle (OR=0.835,95%CI 0.775~0.900) were all independent risk factors for postoperative joint stiffness (all P<0.05).A nomogram model was constructed based on the above factors,and the areas under the ROC curve (AUC) for internal validation (nP=227) and external validation (nP=50) were 0.894 and 0.776,respectively. Conclusion Patients undergoing rotator cuff suture who have shoulder joint stiffness before the operation,excessive acromial index or smaller lateral acromial angle in the early postoperative period are more likely to develop joint stiffness after surgery.The column chart prediction model constructed using the above factors has shown good performance in predicting joint stiffness in patients.

Key words: rotator cuff suture; joint stiffness; anatomy