Preventing secondary screw perforation following proximal humerus fracture after locking plate fixation: a new clinical prognostic risk stratification model.

INTRODUCTION: After locking plate (LP) fixation, secondary screw perforation (SSP) is the most common complication in proximal humerus fracture (PHF). SSP is the main cause of glenoid destruction and always leads to reoperation. This study aimed to identify independent risk parameters for SSP and establish an individualized risk prognostic model to facilitate its clinical management. METHODS: We retrospectively reviewed the medical information of patients with PHF who underwent open reduction and internal LP fixation at one medical center (n = 289) between June 2013 and June 2021. Uni- and multivariate regression analyses identified the independent risk factors. A novel nomogram was formulated based on the final independent risk factors for predicting the risk of SSP. We performed internal validation through concordance indices (C-index) and calibration curves. To implement the clinical use of the model, we performed decision curve analyses (DCA) and risk stratification according to the optimal cutoff value. RESULTS: A total of 232 patients who met the inclusion criteria were enrolled. The incidence of SSP was 21.98% at the last follow-up. We found that fracture type (odds ratio [OR], 3.111; 95% confidence interval [CI], 1.223-7.914; P = 0.017), postoperative neck-shaft angle (OR, 4.270; 95% CI 1.622-11.239; P = 0.003), the absence of calcar screws (OR, 3.962; 95% CI 1.753-8.955; P = 0.003), and non-medial metaphyseal support (OR,7.066; 95% CI 2.747-18.174; P = 0.000) were independent predictors of SSP. Based on these variables, we developed a nomogram that showed good discrimination (C-index = 0.815). The predicted values of the new model were in good agreement with the actual values demonstrated by the calibration curve. Furthermore, the model's DCA and risk stratification (cutoff = 140 points) showed significantly higher clinical benefits. CONCLUSIONS: We developed and validated a visual and personalized nomogram that could predict the individual risk of SSP and provide a decision basis for surgeons to create the most optional management plan. However, future prospective and externally validated design studies are warranted to verify our model's efficacy.

[Pathological observation of femoral refracture after removal of plates].

OBJECTIVE: To discuss the reasons and the treatments for the femoral refracture. METHODS: From 2004 to 2008, 10 cases of femoral refracture after plate removal were selected and treated with open reduction and bone nail internal fixation, included 4 males and 6 females ranging from 19 to 48 years with an average age of 33 years old. According to Müller classification, there were 4 cases of type A, 3 of B, 3 of C. The skeletal tissues were taken for pathological analysis. RESULTS: Ten patients were followed-up for 10 to 18 months (averaged 14 months). All wound healed at one stage,there were no complications. The fuction of lower limbs walking and weight loading werer recovered. Pathological section showed that part of the lamellar bone tissues were necrotic. The bone architectures were chaotic, micrangium blocked, Haversian canals were atrophy, new vessels and Haversian canals growed in necrotic bone. The tunnel in rigid bone and new Haversian system were formed. The structure was cutting cone. It was the process of new bone substitutting necrotic bone in bony remodeling. CONCLUSION: The internal fixation using ordinary plates overwhelmingly destroy blood circulation of bone and cause necrosis of bone. It can also effect bone remodeling and descent mechanical property. Refracture can readily happen after the plate removal. Treatment of open reduction and bone nail internal fixation can achieve excellent and good effect.