Published simulator studies for metal/UHMWPE bearings couples showed that increasing the femoral head diameter by 1 mm increases wear by approximately 10% due to increased contact area. Therefore, there are concerns about increased wear with dual mobility hip bearings. The purpose of the study was to compare wear from dual mobility hip bearings to that with traditional fixed bearings. In addition, for the dual mobility bearings, the effect of femoral head material type on the liner wear was also evaluated.Background
Purpose of the study
Decreasing tissue damage and recovery time, while improving quality of life have been the focus of many approaches to total hip arthroplasty (THA). In this study, we compared two approaches, a tissue-sparing superior capsulotomy percutaneously assisted approach (SP) and the traditional posterior approach (TR), to address the question of whether the novel technique reduces tissue damage. The secondary aim of this study focused on the measurement technologies utilized to quantify the damage resulting from either SP or TR. Image J, BioQuant, and cellSens were the image analysis programs employed. Statistical validation and comparisons of results between all platforms were performed. Both hips of freshly frozen cadaveric specimens (n = 8) were surgically prepared for THA with random procedure performed on left or right hip. All selected specimens had no prior implantation of devices to ensure all observed muscle damage occurred from the surgical technique. Surgeons resected tissue and performed necessary procedural steps up to device implantation. No devices were implanted during the study, as the aim was to quantify the damage caused by the incision and resection. After completion of the surgery, an independent surgeon (IS), who was blinded as to which method was performed on the specimen, excised the muscles and inspected areas of interest Assessment of the tissue damage was executed using a midsubstance cross-sectional area technique, validated by prior studies. High-resolution images of demarcated muscles were used for quantitative analysis. Three blinded independent reviewers quantified damaged tissue. The results were used to detect if statistically significant differences were present between the two methods. Furthermore, an independent reviewer using SPSS statistical software also assessed inter-program and inter-rater reliability.Introduction
Methods
Laser marking of implants surfaces is necessary in order to provide traceability during revisions which will help identify product problems more quickly, better execute product recalls and improve patient safety. There are several methods of marking employed within the medical field such as chemical etching, electro pencil marking, mechanical imprinting, casting of markings, marking with vibratory type contact, ink jet, hot foil and screen printing. However, these methods have various drawbacks including marking durability or addition of potentially toxic chemical compounds. As a result laser marking has become the preferred identification process for orthopedic implants. Laser marking is known for its high visual quality, good reproducibility and precision. However there are concerns about the laser marking potential to affect fatigue life of a device. There is a limited number of research papers that studied the effect of laser marking on fatigue life of implants. The objective of the current study is to investigate the effects of laser marking on the fatigue life of titanium alloy material. Two groups of four point bend specimens were used to investigate the effect of laser marking on the fatigue life. The first group comprised of the specimens without laser marking while the second group comprised of specimens with laser marking currently utilized for the implant surfaces. Prior to conducting the fatigue testing, a non-destructive X-ray diffraction (XRD) residual stress analysis was conducted to determine if the laser marking had introduced any residual stresses. Imaging analysis was also conducted to examine any potential surface damage on the test sample's surface. A servo-hydraulic test machine was used for the fatigue four point bend testing regime where the inner and outer spans were 30 mm and 90 mm respectively. All testing was conducted at a frequency of 10 Hz, a stress ratio R=0.1, and sine-wave loading in air. Testing was stopped at 10 Million cycles or at failure of the specimen.Introduction
Material and Methods
Recently there have been case reports of component fractures and elevated metal ion levels potentially resulting from the use of cobalt-chrome modular necks in total hip arthroplasty. One potential cause that has been suggested is fretting corrosion caused by micromotion at the taper junction between the modular neck and the femoral stem. The objective of the current study was to investigate the effects of various impaction and loading methods on micromotion at the modular neck-femoral stem interface in a total hip replacement system. A femoral stem was potted using dental acrylic and displacement transducers were inserted to measure micromotion in the modular neck pocket (Figure 1a). An 8° varus, long, cobalt-chrome, modular neck and 28 mm XXL cobalt-chrome femoral head were inserted in the femoral stem using various assembly techniques (a) hand assembly, (b) impaction loads: 2, 3, 4, 6, 16.4 kN and (c) INTRODUCTION
METHODS
Total knee replacement (TKR) implant designs and materials have been shown to have a significant impact on tibial insert wear. A medial-pivot (MP) design theoretically should generate less wear due to a large contact area in the medial compartment and lower contact stresses. Synovial fluid aspiration studies have confirmed that a first generation MP TKR system (ADVANCE®, MicroPort Orthopedics Inc., Arlington, TN, USA) generates less wear debris than is seen with other implant designs articulating against conventional polyethylene (CP). The objective of this study was to evaluate the Introduction
Objectives
