Biomechanical effects of screws of different materials on vertebra-pediculoplasty: a finite element study.

Background: The effects of cannulated screws made of polyetheretherketone (PEEK) on the biomechanical properties of the vertebral body during vertebra-pediculoplasty remain unclear. This study aimed to investigate whether PEEK screws have the potential to replace titanium alloy screws. Methods: The surgical model of two different materials of screws was constructed using the finite element method. The biomechanical effects of the two models on the vertebral body under different working conditions were compared. Results: ① The peak von Mises stress of PEEK screws was significantly lower than that of titanium screws, with a reduction ranging from 52% to 80%. ② The von Mises stress values for the injured T12 spine were similar for both materials. Additionally, the segmental range of motion and intervertebral disc pressure showed no significant difference between the two materials. Conclusion: PEEK screws demonstrated advantages over titanium screws and may serve as a viable alternative for screw materials in vertebra-pediculoplasty.

[Research status of acetabular reconstruction in Crowe type â ¡ and â ¢ developmental dysplasia of the hip].

Developmental dysplasia of the hip (DDH) is a major cause of hip arthritis and ultimately total hip arthroplasty. Due to the dysplastic acetabulum, how to place the acetabular cup becomes a challenge in acetabular reconstruction for such patients. Especially in the acetabula classified as Crowe typeⅡand type Ⅲ, the dislocation of the femoral head causes bone defects above the true acetabulum, which will affect the stability of the acetabular cup when the acetabular reconstruction is performed at the true acetabulum. Many acetabular reconstruction methods such as bone grafting, the use of small acetabular cups, socket medialization technique, and high hip center technique are used to increase the host bone coverage of the cup. However, each method has its own shortcomings that can not be ignored so that there is no unified conclusion on the acetabular reconstruction methods for Crowe typeⅡand type Ⅲ hip dysplasia. This article summarized and evaluated various reconstruction methods in combination with the acetabular morphology of DDH, and put forward the research direction in the future.