A 43-year-old drug addicted female was referred for a L5-S1 posterolateral in situ fixation with autologous graft because of an L5/S1 severe discopathy with listhesis. After six months, low back pain recurred. A Tc-99m HDP SPECT-CT diagnosed a pseudarthrosis with intense uptake of the L5-S1 endplates and a fracture of the right S1 screw just outside the metal-bone interface without any uptake o...

Bone weakness leading to refracture is a recognised complication of the removal of rigid fixation plates. We have used partially demineralised rabbit tibiae to simulate atrophic changes and to determine whether weakness is due to atrophy or to residual screw holes. Partial demineralisation and a screw hole each reduced maximum bending moment. However, energy absorbing capacity was little affect...

PURPOSE The purpose of this study was to histologically and immuno-histochemically evaluate tissue changes in the maxillary sinus after bone screw implantation and maxillary sinus augmentation using self-setting α-tricalcium phosphate (α-TCP; BIOPEX(®)-R) in rabbit. STUDY DESIGN Adult male Japanese white rabbits (n=15, 12-16 weeks, 2.5-3 kg) were used. The sinus lift was made from the nasal b...

Using finite element analysis, a parametric study was developed to compare stress and strain energy density (SED), in order to determine which stimuli might be better for predicting stress shielding in bone-screw models. Defined stimuli transfer parameters demonstrated that stress and SED (strong candidates for initiating the bone remodeling process) are transferred distinctively between an imp...

In this study, injection molding of three poly lactic acid (PLA) based bone screws was simulated and optimized through minimizing the shrinkage and warpage of the bone screws. The optimization was carried out by investigating the process factors such as coolant temperature, mold temperature, melt temperature, packing time, injection time, and packing pressure. A response surface methodology (RS...

The mechanical fixation of endosseous implants, such as screws, in trabecular bone is challenging because of the complex porous microstructure. Development of new screw designs to improve fracture fixation, especially in high-porosity osteoporotic bone, requires a profound understanding of how the structural system implant/trabeculae interacts when it is subjected to mechanical load. In this st...

Introduction: Most fractures occur in osteoporotic cancellous bone in metaphyseal regions. The response to the trauma of inserting a screw in cancellous bone appears similar to metaphyseal fracture repair. The formation of new bone around a screw determines the strength of its fixation. Hence, the bone regenerative response can be measured as a pull-out force. Sclerostin, a secreted glycoprotei...

Objectives To analyse whether there is a difference in marginal bone levels (MBL) and the respective changes between cemented screw-retained reconstructions at 3 5 years of loading. Methods Radiographic data from 14 prospective multicentre clinical trials following implant loading with fixed (CEM) or (SCREW) 3- to 5-year follow-up were retrieved database. MBL assessed initiation (BL), (FU-3) (F...

An obvious means to improve the fixation of a cancellous bone screw is to augment the surrounding bone with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement significantly improves screw fixation. Nevertheless, quantitative data about the optimal distribution of CaP cement is not available. The present study aims to show the effect of cement distribu...

BACKGROUND Due to complex pelvic geometry, percutaneous screw placement in the posterior acetabular column can pose a major challenge even for experienced surgeons. METHODS The present study examined the preformed bone stock of the posterior acetabular column in 260 hemipelvises. Retrograde posterior column screws were virtually implanted using iPlan CMF (BrainLAB AG, Feldkirchen, Germany); m...