Biomechanical analysis of two medial buttress plate fixation methods to treat Pauwels type III femoral neck fractures

Background Femoral neck fractures in young people are usually Pauwels Type III fractures. The common treatment method are multiple parallel cannulated screws or dynamic hip screw sliding compression fixation. Due to the huge shear stress, the rate of complications such as femoral head necrosis and nonunion is still high after treatment. The aim of our study was to compare the stabilities of two fixation methods in fixating pauwels type III femoral neck fractures. Methods All biomimetic fracture samples are fixed with three cannulated screws combined with a medial buttress plate. There were two fixation groups for the buttress plate and proximal fracture fragment: Group A, long screw (40 mm); Group B, short screw (6 mm). Samples were subjected to electrical strain measurement under a load of 500 N, axial stiffness was measured, and then the samples were axially loaded until failure. More than 5 mm of displacement or synthetic bone fracture was considered as construct failure. Results There were no significant differences in failure load (P = 0.669), stiffness (P = 0.842), or strain distribution (P > 0.05) between the two groups. Conclusions Unicortical short screws can provide the same stability as long screws for Pauwels Type III Femoral Neck Fractures.

Short-Term Clinical Efficacy of Femoral Neck System Versus Multiple Cannulated Compression Screws in the Treatment of Garden III and IV Femoral Neck Fractures

Femoral neck system (FNS) , as a novel minimally invasive internal fixation device, has been gradually applied in the treatment of femoral neck fracture.However, there are few related clinical studies on FNS at present, especially there is no clinical report on FNS in treating GardenIII and IV femoral neck fractures. The aim of the present study was to compare the short-term clinical efficacy of FNS and multiple cannulated compression screws (MCCS) in the treatment of Garden III and IV femoral neck fractures. The data of 78 patients with femoral neck fracture who were admitted to three teaching hospitals affiliated to Anhui Medical University and received internal fixation with FNS and MCCS from June 2019 to December 2020 were collected for a retrospective study. There were 39 patients in both the FNS and MCCS groups. The basic data, perioperative data were recorded and compared between the two groups of patients. The results of the study are encouraging. The operation time was shorter in FNS group than that in MCCS group (p<0.001). The post-operative partial and complete weight-bearing time was earlier in FNS group than that in MCCS group (p<0.001). The Harris hip score in FNS group was higher than that in MCCS group (p<0.001). The incidence rate of lateral thigh irritation in FNS group and MCCS group was 0 (0/39) and 33.3% (13/39), respectively (χ2=15.600, p<0.001). The length of femoral neck shortening was significantly shorter in FNS group than that in MCCS group (t=-5.093, p<0.001). In conclusion, The application of FNS for Garden III and IV femoral neck fractures can shorten the operation time, reduce the frequency of intraoperative fluoroscopy, and facilitate the recovery of hip joint function, so it provides a novel choice for the treatment of Garden III and IV femoral neck fractures in young people.

The oblique triangle configuration of three parallel screws for femoral neck fracture fixation using computer-aided design modules

Closed reduction and internal fixation with three cannulated compression screws is a common method for treating femoral neck fractures in young and middle-aged patients. Protocols including the inverted triangle configuration and dispersion of the screws still needed further supports. The purpose of this study was to explore a novel oblique triangle configuration (OTC) of three screws in fixing femoral neck fractures based on the morphology of the femoral neck isthmus (FNI). The computer-aided design modules were used to explore the ideal spatial configuration with largest triangle by three parallel screws. A univariate evaluation model was established based on the oval-like cross-section of the FNI. When the three screws were positioned by the OTC, Inverted Equilateral Triangle Configuration (IETC), and the Maximum Area Inverted Isosceles Triangle Configuration (MA-IITC) respectively, the proportion of area and circumference in the cross-section of FNI and the changing trend of proportion were compared under various torsion angles, eccentricity, and cross-sectional area of FNI. The area and circumference ratios of the parallel screws using the OTC method were significantly higher than in the IETC and MA-IITC groups. In the univariate evaluation model, the OTC area ratio and circumference ratio remained stable under the different femoral neck torsion angles, FNI cross-sectional area, and eccentricity. The OTC method provided an ideal spatial configuration for the FNA fixation with the largest area using three parallel screws. The position of the posterior screw was also away from the metaphyseal artery, potentially reducing the possibility of vascular injury and screw penetrating.

Clinical Outcome and Biomechanical Analysis of Dynamic Hip Screw Combined with Derotation Screw in Treating Displaced Femoral Neck Fractures Based on Different Reduction Qualities in Young Patients (≤65 Years of Age)

Objective. To examine the clinical results and biomechanical mechanism of the dynamic hip screw (DHS) and derotation screw (DS) in the treatment of displaced femoral neck fractures (FNF) based on different reduction qualities in young patients (≤65 years of age). Methods. All patients with FNF who received closed reduction and internal fixation with DHS+DS from January 2014 to August 2019 were retrospectively analyzed. Data on demographics, surgery, clinical outcomes, and postoperative complications were collected. According to the reduction quality immediately after surgery, all patients were categorized into the positive buttress reduction group (PBRG) and the anatomical reduction group (ARG). The complications and clinical outcomes were compared between the two groups. Meanwhile, the biomechanical mechanism of different reduction qualities was further analyzed with finite element analysis (FEA). The distribution of von Mises stress, the peak stress of internal fixation, and the displacement of the proximal fragment were compared between the two groups. Results. A total of 68 patients were included in our study. Among them, 31 were divided into the PBRG while 37 were in the ARG. The surgical time and fluoroscopy time were significantly shorter in the PBRG than in the ARG ( p < 0.05 ). The degree of femoral neck shortening and the varus change of the femoral-neck shaft angle were lower in the PBRG compared to the ARG ( p < 0.05 ). The excellent-good rate of the Harris hip score was higher in the PBRG compared to the ARG (83.9% vs. 64.8%). The FEA results demonstrated that the stress of DHS+CS and the downward displacement of the proximal femoral neck fragment were greater in the ARG than in the PBRG. Conclusion. For displaced FNF with difficulty to achieve reduction, DHS+CS combined with positive buttress reduction was an effective treatment in young patients due to better mechanical support, shorter surgical time, less radiation exposure, and higher excellent-good rate of Harris hip score.

A Simple Diagnosis-Related Groups-Based Reimbursement System Is Cost Ineffective for Elderly Patients With Displaced Femoral Neck Fracture Undergoing Hemiarthroplasty in Beijing

Displaced femoral neck fractures (FNF) in the elderly are a major public health concern that necessitates hemiarthroplasty (HA) as the mainstay treatment option. Diagnosis-Related Groups (DRG) are a patient classification system that categorizes patients based on the resources expended on them. The first objective of this study was to evaluate if a simplified DRG-based reimbursement system in Beijing would lower total HA treatment costs for elderly patients with displaced FNF. In addition, we aimed to determine how age, gender, year of admission, length of in-hospital stay, and the Charlson index affected total treatment costs. This retrospective study included 513 patients from the Peking Union Medical College Hospital. The patients were diagnosed with unilateral displaced femoral neck fractures and had HA. Medical information was gathered, including baseline demographic and clinical data, as well as treatment costs. Patients were classified into two groups: those who spent more than the predetermined cut-off cost and those who did not. The cost did not include the use of a bipolar prosthesis. Data from the two groups were compared, and multiple regression analysis models were constructed. The median total cost of treatment was ¥49,626 ($7,316). The majority of the patients (89.7%; 460/513) were categorized as exceeding the cost cut-off. Multiple linear regression analysis revealed that total treatment cost was positively correlated with age (p &lt; 0.01) and the duration of in-hospital stay (p &lt; 0.01) but not with gender (p = 0.160) or the Charlson index (p = 0.548). On implementing the DRG-based reimbursement system, the overall treatment costs increased by ¥21,028 ($3,099) (p &lt; 0.01). The implementation of simplified DRG-prospective payment systems did not result in a significant reduction in total treatment costs for elderly patients with FNF who underwent HA in Beijing. The overall cost of treatment was associated with several factors, including age, length of hospitalization, and year of admission.