Acetabular Defects of Hip Tuberculosis: Recommended Classification and Reconstruction in Hip Arthroplasty

Background: This study aimed to propose a classification of acetabular defects in advanced-stage hip tuberculosis based on preoperative radiographs and intraoperative evaluation, thereby providing options for reconstructing each type of defect in hip arthroplasty. Materials and Methods: We conducted a prospective study with 45 patients with active hip tuberculosis at stage IV who were treated with a total hip replacement strategy. We collected the patients’ acetabular defect data from preoperative radiographs and intraoperative observations. The defects were classified into types based on defect severity and reconstructive complexity. The hip replacement outcomes were evaluated at least 12 months after the operation. Results: The classification system includes three types: type I: localized or extensive defects inside the acetabulum, not affecting the acetabular rim, medial wall, or columns. Type II: extensive defects inside the acetabulum, affecting the acetabular rim or (and) medial wall. Type III: extensive defects inside the acetabulum, causing the medial wall and the acetabular column to lose function. Each type has a corresponding reconstruction. The outcome includes that 41/45 patients had excellent results;3/45 patients had good results. The patients had good results due to nerve and muscle damage caused by tuberculosis not related to the acetabular defects. Conclusion: This is a simple, practical classification system of acetabular defects in hip tuberculosis. The outcome of hip reconstruction using this classification was excellent without any cases of dislocation or protrusion.

3D Printing Hip Prostheses Offer Accurate Reconstruction,Stable Fixation,and Functional Recovery for Revision Total Hip Arthroplasty with Complex Acetabular Bone Defect

Complicated and large acetabular bone defects present the main challenges and difficulty in the revision of total hip arthroplasty(THA).This study aimed to explore the advantages of three-dimensional(3D)printing technology in the reconstruction of such acetabular bone defects.We retrospectively analyzed the prognosis of four severe bone defects around the acetabulum in three patients who were treated using 3D printing technology.Reconstruction of bone defect by conventional methods was difficult in these patients.In this endeavor,we used radiographic methods,related computer software such as Materialise's interactive medical image control system and Siemens NX software,and actual surgical experience to estimate defect volume,prosthesis stability,and installation accuracy,respectively.Moreover,a Harris hip score was obtained to evaluate limb function.It was found that bone defects could be adequately reconstructed using a 3D printing prosthesis,and its stability was reliable.The Harris hip score indicated a very good functional recovery in all three patients.In conclusion,3D printing technology had a good therapeutic effect on both complex and large bone defects in the revision of THA.It was able to achieve good curative effects in patients with large bone defects.

Application of Acetabular Reinforcement Ring with Hook for Correction of Segmental Acetabular Rim Defects during Total Hip Arthroplasty Revision

This study investigated the biomechanical micro-motion associated with the application of acetabular reinforcement ring with hook （Ganz ring） for the correction of segmental acetabular rim defects, by finite element analysis. The objective was to determine whether the Ganz ring is suitable for correcting segmental acetabular rim defects at different regions during total hip arthroplasty revision as well as the number of screws required to fix the Ganz ring. A finite element model of the hip joint was generated to simulate and evaluate the insertion and fixation of the Ganz ring and acetabular cup in the context of segmental rim defects in the anterior column, superior portion, and posterior column. Micro-motion was the greatest in the posterior column defect and the least in the anterior column defect. However, the peak stress distribution on the remaining portion of the acetabular rim was the highest in the superior portion defect, following the pos- terior column defect and anterior column defect. Increasing the number of fixations of the Ganz ring did not decrease the micro-motion. We found that the Ganz ring effectively provided biomechanical stability during the reconstruction of the segmental rim defect as long as the screws fixed the Ganz ring well to the host bone.

Application of Novel Design Bone Grafting for Treatment of Segmental Acetabular Rim Defects During Revision Total Hip Arthroplasty

The study aimed to develop efficient techniques with different novel graft structures to enhance the treatment of acetabular bone deficiency.The inhomogeneous material properties Finite Element Analysis(FEA)model was reconstructed according to computed tomography images based on a healthy patient without any peri-acetabular bony defect according to the American Academy of Orthopedic Surgeons(AAOS).The FEA model of acetabular bone deficiency was performed to simulate and evaluate the mechanical performances of the grafts in different geometric structures,with the use of fixation implants(screws),along with the stress distribution and the relative micromotion of graft models.The stress distribution mainly concentrated on the region of contact of the screws and superolateral bone.Among the different structures,the mortise-tenone structure provided better relative micromotion,with suitable biomechanical property even without the use of screws.The novel grafting structures could provide sufficient biomechanical stability and bone remodeling,and the mortise-tenone structure is the optimal treatment option for acetabulum reconstruction.

Jumbo Bionic Trabecular Metal Acetabular Cups Improve Cup Stability During Acetabular Bone Defect Reconstruction:A Finite Element Analysis Study

The biomechanical effects of acetabular revision with jumbo cups are unclear.This study aimed to compare the biomechanical effects of bionic trabecular metal vs.titanium jumbo cups for the revision of acetabular bone defects.We designed and reconstructed American Academy of Orthopaedic Surgeons(AAOS)type I–III acetabular bone defect models using computed tomography scans of a man without acetabular bone defects.The implantation of titanium and trabecular metal jumbo cups was simulated.Stress distribution and relative micromotion between the cup and host bone were assessed using finite element analysis.Contact stress on the screws fixing the cups was also analyzed.The contact stress analysis showed that the peak contact stress between the titanium jumbo cup and the host bone was 21.7,20.1,and 23.8 MPa in the AAOS I–III models,respectively;the corresponding values for bionic tantalum jumbo cups decreased to 4.7,6.7,and 11.1 MPa.Analysis of the relative micromotion showed that the peak relative micromotion between the host bone and the titanium metal cup was 10.2,9.1,and 11.5μm in the AAOS I–III models,respectively;the corresponding values for bionic trabecular metal cups were 17.2,18.2,and 31.3μm.The peak contact stress on the screws was similar for the 2 cup types,and was concentrated on the screw rods.Hence,acetabular reconstruction with jumbo cups is biomechanically feasible.We recommend trabecular metal cups due to their superior stress distribution and higher relative micromotion,which is within the threshold for adequate bone ingrowth.