Basic Science Considerations in Primary Total Hip Replacement Arthroplasty

Total Hip Replacement is one of the most common operations performed in the developed world today. An increasingly ageing population means that the numbers of people undergoing this operation is set to rise. There are a numerous number of prosthesis on the market and it is often difficult to choose between them. It is therefore necessary to have a good understanding of the basic scientific principles in Total Hip Replacement and the evidence base underpinning them. This paper reviews the relevant anatomical and biomechanical principles in THA. It goes on to elaborate on the structural properties of materials used in modern implants and looks at the evidence base for different types of fixation including cemented and uncemented components. Modern bearing surfaces are discussed in addition to the scientific basis of various surface engineering modifications in THA prostheses. The basic science considerations in component alignment and abductor tension are also discussed. A brief discussion on modular and custom designs of THR is also included. This article reviews basic science concepts and the rationale underpinning the use of the femoral and acetabular component in total hip replacement

An evaluation of CT-scan to locate the femoral head centre and its implication for hip surgeons

The aim of this preliminary study was to determine the accuracy of CT-scan to locate the femoral head centre. METHODS: Eleven dried femurs were included for study. Three techniques were compared to determine femoral head centre (FHC) location: CT-scan, Motion Analysis and Faro-Arm. Markers were stuck on each femur to create a system of coordinates. Femurs lied on their posterior parts (bicondylar plane). Several points around the femoral head were palpated (Motion Analysis and Faro-Arm) or determined (Amira software for CT-scans). By a least-square regression method, the FHC location in 3D was defined for each technique. RESULTS: The results of the FHC location determined by the CT-scan technique were compared with those measured by the faro-arm and the Motion Analysis techniques. The coordinates (X, Y, Z) of the FHC were compared between the three methods, and no statistical difference was found (p = 0.99). In a 3D plot, this gave a mean difference of 1.3 mm. The mean radius of the femoral head was of 22.5 mm (p = 0.6). CONCLUSIONS: CT-scan is as accurate and reliable as gold-standard techniques (motion and faro-arm). Locating FHC before and after hip arthroplasty would allow hip surgeons to determine and compare 3D orientation of the upper-end of femur: offset, height and anteversion