Endplate defect is an MRI trait, found to be associated with intervertebral disc degeneration. There is a lack of understanding regarding the mechanism underlying lumbar disc degeneration (LDD). This large-scale longitudinal population-based study aimed to determine the order of appearance of degenerative change in the vertebral body and intervertebral disc, the influence of endplate degeneration on LBP and whether there is a genetic influence on endplate damage. Individuals from the TwinsUK spine study having longitudinal T2-weighted lumbar MRI scans at baseline (n=996) and a decade later (n=438) were included. LDD, vertebral endplate defect expressed as a total endplate (TEP) score and Modic change (MC) were assessed using standard techniques. Mixed-effects models were used to determine the association between spine pathology features adjusted for covariates. Endplate defect heritability was estimated using variance component analysis.Background
Methods
This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris.Objectives
Methods
Cementless devices can be designed with varying surface treatments with the hope of achieving osseointegration. The surface finish dictates the interaction, adhesion and growth of bone therefore it is an important parameter that be measured and compared. The surface topography of a material can be viewed both microscopically and macroscopically. Surface microtopography focuses on the peaks and valleys where deviations in the characteristics of the size and spacing of these features determine the variability between surface topography. The most common parameter used worldwide to describe surface roughness is the arithmetic average height (Ra). The definition of Ra is the absolute deviation of the surface irregularities from a mean line across the sampling length given by the equation shown in figure 1. Many techniques can be used to relate to surface characteristics of materials, with the common two options revolving around contact and non-contact methods. These techniques are expensive and are limited in detecting the interaction of implantable devices at a macroscopic level. This study sought to develop a method to determine the surface roughness and characterise implants based on cross sectional images and scanning electron microscopy. The profile of 6 trunnions from a total hip replacement was obtained in x and y coordinates along a set length using a profilometer. A custom program to calculate the Ra of the material was created using a mathematical program (MATLAB). Each material profile was inputted into a mathematical program to provide the surface roughness of the material. The surface parameters were initially obtained from a surface analyser to determine the accuracy of the program.Introduction
Method
Dislocation is one of the leading causes of revision after primary total hip arthroplasty (THA). Polyethylene wear is one of the risk factors for late dislocations (>2 years). It can induce an inflammatory response resulting in distension and thinning of the pseudocapsule, predisposing the hip to dislocation. Alternatively, eccentric seating of the femoral head in a worn out socket may result in an asymmetric excursion arc predisposing the hip to impingement, levering out and dislocation. Highly cross linked polyethylene has a significantly lower wear rate as compared to conventional polyethylene. Incidence of late dislocations has been shown to be significantly greater with conventional polyethylene bearings as compared to ceramic bearings. However, there is no literature comparing the risk of dislocation between ceramic- on- ceramic (CoC) bearings with metal/ceramic- on- cross linked polyethylene (M/CoP) bearings and this was the aim our study Data regarding revision for dislocation after primary THA for osteoarthritis (OA) between September 1999 and December 2013 was obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOA NJRR). Revision risk for dislocation was compared between CoC, CoP, and MoP bearings. Only those THAs with 28 mm, 32 mm, or 36 mm heads were included in the study.Introduction
Methods
Modern hip replacements all have encapsulated the design concept of proximal modularity. The factors contributing to the increased wear and corrosion at the taper junction are trunnion geometry, surface characteristics, head size, impaction forces, and material coupling. This study maps the inferior and superior region of the trunnion and bore to provide a visual identification of the corrosion severity. The corrosion/wear generated inferiorly and superiorly at the bore and trunnion will be quantified to understand how corrosion is affected by mechanical stresses in relation to anatomical orientation. Three neck tapers generated from bar stock containing a threaded trunnion Ti-6Al-4V and 3× 32mm femoral heads (Co-Cr-Mo) with a +4 offset manufactured by Signature Orthopaedics were used within this study. Rectangular Rozzette strain gauges (Tokyo Sokki Kenkyujo Co., Ltd.) were adhered onto the inferior and superior sections of the neck section. The tapers were fatigued in accordance to ISO 7206 at 5Hz for 5 million cycles at 37 degrees Celsius in phosphate buffered saline. The tapers were sectioned from the center of the femoral head to split both trunnion and bore into superior and inferior components. SEM imaging of all surface areas for each component, per taper (4) was done under ×100 magnification. The images were used to quantify the corrosion present across the surface area using a MATLAB based program called Histomorph. To obtain a visual observation of the variation of corrosion across the bore and trunnion the proximal, medial, and distal regions were mapped together for both the superior and inferior sections.Introduction
Methodology
The possibility of corrosion at the taper junction of hip replacements was initially identified as a concern of generating adverse reactions in the late 1980s. Common clinical findings of failure are pain, clicking, swelling, fluid collections, soft tissue masses, and gluteal muscle necrosis identified intra operatively. The joint replacement surgery was performed utilizing a posterior approach to the hip joint. The data from all surgical, clinical and radiological examinations was prospectively collected and stored in a database. Patients were separated into two groups based on bearing material, where group 1 had a CoC bearing and ABG modular stem whilst group 2 had a MoM bearing and SROM stem, with each group having 13 cases. Pre-operative revision surgery and post-operative blood serum metal ion levels we collected. Cup inclination and anteversion was measured using the Ein-Bild-Roentgen-Analyse (EBRA) software. A range of 2–5 tissue sections was examined per case. 2 independent observers that were blinded to the clinical patient findings scored all cases. The tissue grading for the H&E tissue sections were graded based on the presence of fibrin exudates, necrosis, inflammatory cells, metallic deposits, and corrosion products. The corrosion products were identified into 3 groups based on visible observation and graded based on abundance. A scanning electron microscope (SEM) Hitachi S3400 was used to allow for topographic and compositional surface imaging. Unstained tissue sections were used for imaging and elemental analysis. X-Ray diffraction was the analytical technique used for the taper debris that provided identification on the atomic and molecular structure of a crystal.Introduction
Methodology
Sagittal stability of the knee is believed to be of significant importance following total knee arthroplasty. We examine four different knee designs at a minimum of twenty-four months postoperatively. Sagittal stability was measured at four degrees of flexion: 0°; 30°; 60°; and 90°, to examine the effect of design on mid-flexion stability. The knee designs included were: the rotating platform LCS design (DePuy); the cruciate sparing Triathlon system (Stryker); SAIPH system (Matortho, UK); and the medial rotating knee design, MRK (Matortho, UK). Following ethical approval, 64 cases were enrolled into the study, 22 male and 42 female. Inclusion criteria included: a minimum of 18 months from surgery; ability to flex beyond 90 degrees; and have no postoperative complications. 18 LCS, 18 MRK, 14 SAIPH and 14 Triathlon knee designs were analysed. Sagittal stability was measured using the KT1000 device. Active range of movement was measured using a hand held goniometer and recorded as was Oxford knee score, WOMAC knee score, SF12 and Kujala patellofemoral knee score. Mean follow-up was 33.7 months postoperative, with a mean age of 72 years. Mean weight was 82.7kgs and height 164cms. There was no significant difference in preoperative demographics between the groups. Mean active post-operative range of motion of the knee was from 2–113° with no significant difference between groups. Sagittal stability was similar in all four groups in full extension; however the MRK and SAIPH designs showed improved stability in the mid-range of flexion (30–90°). Patient satisfaction also showed a similar trend with MRK achieving better patient reported functional outcomes and satisfaction than that of the SAIPH, LCS and Triathlon systems. All four knee designs demonstrated good post-operative range of movement with comparative improvement of patient scores to other reported studies. The MRK and SAIPH knee design showed an improved mid-flexion sagittal stability with better patient reported satisfaction and functional scores.
The aim of this study is to describe the influence of sitting and standing posture on sagittal pelvic inclination in preoperative total hip replacement patients to assist with correct acetabular component positioning. Lateral radiographs of the pelvis and lumbar spine in sitting and standing of preoperative hip arthroplasty patients with primary hip osteoarthritis were extracted. Pelvic tilt was measured using the vertical inclination of a line from the ASIS to pubic tubercle. Sacral inclination was measured as the angle between the anterior surface of the sacrum and a horizontal reference. Figure one is a representation of the pelvic tilt angle and sacrel inclination angle taken during standing. The Cobb angle of the lumbar spine was recorded represented for a sitting patient in figure 2. Hip flexion was recorded (figure 2).Purpose
Methods
Squeaking is a potential problem of all hard on hard bearings yet it has been less frequently reported in metal-on-metal hips. We compared a cohort of 11 squeaking metal-on-metal hip resurfacings to individually matched controls, assessing cup inclination and anteversion between the groups to look for any differences. We retrospectively reviewed the patient records of 332 patients (387 hip resurfacings) who underwent hip resurfacing between December 1999 and Dec 2012. 11 hips in 11 patients were reported to squeak postoperatively. Each of these patients, except one, were matched by age, sex, BMI and implant to 3 controls. The final patient only had one control due to his high BMI. The latest post-operative radiographs of the squeaking group and controls were analysed using EBRA (Einzel-Bild-Roentgen-Analysis, University of Innsbruck, Austria) software to evaluate cup inclination and anteversion.Introduction
Methods
The Morse taper was adapted into orthopaedics as a connecting junction in total hip replacements. The benefit of modular systems includes the adjustment of leg length, offset and the ability to remove the head for acetabular exposure during revision surgery. The design of the Morse taper facilitates the intimate contact of the conical trunnion of the femoral stem (male component), with the conical bore of the femoral head (female component). Design consideration for tapers involve physical parameters (angle, length, diameter and contact points), and manufacturing finish (surface characteristics). Orthopaedic trunnion tapers are not standardized and vary in length, taper angle and base dimension. Variations in the design and surface characteristics of the trunnion, which directly reflects on the interface at the taper junction can influence the likelihood of subsequent wear, corrosion and ultimately effect longevity of the implant. We studied 11 clean un-used commercial stems from five different companies (DePuy, Stryker, Biomet, Wright Medical, Smith and Nephew). Trunnion surface was scanned with an optical profilometer (Bruker ContourGT-I 3D Optical Microscope (Karlsruhe, Germany), an interference microscopes with the capability to analyse 3 dimensional topographical features of materials. Three measurements of each trunnion were taken on the anterior surface at the proximal, mid-point, and distal segments. Each region scan was conducted under a 20x objective with the scan length of 1000 um and a back scan of 500 um.Introduction
Methods and Materials
The Delta Motion device (developed by Finsbury Orthopaedics, Leatherhead, United Kingdom, now manufactured by DePuy, Leeds, United Kingdom) is a pre-assembled factory fitted cup. It has been introduced to overcome some of the concerns relating to intra-operative assembly with improper seating of the liner and chipping. This device has a thinner shell and liner in comparison with other cups, allowing the use of larger sized heads which should help reduce the risk of impingement and dislocation. A drawback of the pre-assembled design is the inability to use supplementary screws to achieve stability and the difficulty in obtaining primary stability compared with a thin titanium shell. To date we are not aware of any publications reviewing the outcomes of these devices. 206 DeltaMotion cups were implanted in 195 patients, between Dec 2008 to Dec 2009 by the three senior authors. All the hips had the same stem (Osteonics) and a ceramic head was used. Data was prospectively collected and we reflect on our two year results.Introduction
Methods
Modularity is being increasingly used throughout the world for both primary and revision total hip arthroplasty. Recently there have been concerns of increased corrosion and fretting at the modular junctions. In the SROM® modular hip system, two modular junctions are the head-neck taper junction and the stem-sleeve taper junction. The aim of this study was to investigate corrosion at these junctions with the use of different bearing materials. Between 1994 and 2012, fourty-two patients were revised with SROM® stems. Reasons for revision included aseptic loosening of the cup or stem (11), periprosthetic fracture (2), osteolysis (8), dislocation (13) and other reasons (7). One was revised for stem breakage, and this was excluded from this study. We examined 41 retrieved S-ROM® comprised of 6 metal-on-metal (MOM), 12 metal-on-polyethylene (MOP), 7 ceramic-on-polyethylene (COP) and 16 ceramic-on-ceramic (COC). The orientation for all components was marked at the time of revision surgery. Both the proximal sleeve/stem and the femoral head-neck modular junctions were examined under 10X magnification, and graded by two independent observers. The head tapers were divided into 4 regions, and graded using a previously published 3 point scoring system for fretting and corrosion damage (Goldberg et al, Kop et al), for a total corrosion damage score of 12. The SROM stems were also assessed at the sleeve/stem taper junction. Each stem was divided into 8 quadrants, and graded for corrosion and fretting using the same system as the taper. In addition to severity, we also quantified area of corrosion damage of the stem at the sleeve-stem junction from 0–3, which was multiplied by the severity of damage, to give a score out of 9 for each quadrant (maximum total score of 72 for the stem). The bearing type was unknown to the investigators, so the grading was done in a blinded fashion. Corrosion scores were divided by time to account for differences in time to revision.Introduction
Methods
