Metal-on-metal (MOM) total hip arthroplasty using large diameter femoral heads offer clinical advantages however the failure rates of these hips is unacceptably high. Retrieved hips have a wide range of wear rates of their bearing and taper surfaces and there is no agreement regarding the cause of failure. Detailed visual inspection is the first step in the forensic examination of failed hip components and may help explain the mechanisms of failure. The aim of this study was to determine if there was a correlation between the results of detailed inspections and the volumetric wear of the bearing and taper surfaces of retrieved hips. Detailed, non-destructive macroscopic and stereomicroscopic examinations of 89 retrieved MOM hip components were performed by a single experienced examiner using quantitative assessment to document the severity of 10 established damage features: Light scratches, Moderate scratches, Heavy scratches, Embedded particles, Discolouration, Haziness, Pitting, Visible wear zone, Corrosion, Fretting Each surface was considered in terms of zones comprising of quadrants (cup, head, and taper) and subquadrants (cup and head), Figure 1. Each zone was scored on a scale of 0 to 3 by determining the percentage of the surface area of the zone that exhibited the feature in question: a score of 0=0%, 1<25%, 25%<2<75%, 3>75%. The sum of the scores of each zone was used for the assessment of each damage feature. The volume of wear at the surfaces of each hip was measured with a Zeiss Prismo coordinate measuring machine (cup and head) and a Talyrond 365 roundness measurement instrument (taper), using previously reported methods1, 2. Simple linear regression models were used to asses the univariable associations between the inspection scores and wear volumes. Multiple linear regression models were subsequently used to asses the simultaneous contribution of the inspection scores, found significant in univariable analyses, on the wear outcome variables. All statistical analysis was performed using Stata/IC version 12.1 (StataCorp, USA) and throughout a p value < 0.05 was considered statistically significant.Introduction
Method
It has been suggested that corrosion and fretting at the taper junctions of stemmed metal-on-metal hip replacements may contribute to their high failure rates. A peer-reviewed semi-quantitative scoring system [Goldberg et al., 2002] has been used to visually assess the severity of corrosion and fretting of the taper junction but has not been validated using multiple examiners. The aim of this study was to assess the inter-observer variability of this method. Macroscopic and stereomicroscopic examinations of the femoral head and stem tapers of 100 retrieved large diameter metal on metal (MOM) hip components were performed by two independent observers using the methods defined by Goldberg et al. [2002] to quantify corrosion and fretting. Scores ranging from 1 (none) to 4 (severe) were assigned to the medial, lateral, posterior and anterior quadrants of the neck taper and the distal and proximal regions of the head taper. An overall score was then assigned to each surface as a whole. Cohen's weighted Kappa statistic (κ) was used to measure the inter-observer agreement. A quadratic weighting scheme, that allocated weights to the importance of disagreements that are proportional to the square of the number of categories apart, was used to take account of scaled disagreement. Kappa values were assessed using previously established criteria where κ ≤ 0 = poor, 0.01 to 0.20 = slight, 0.21 to 0.40 = fair, 0.41 to 0.60 = moderate, 0.61 to 0.80 = substantial, 0.81 to 1 = almost perfect. A sample size of 100 was used in order to detect a coefficient of 0.60 to within 0.25 with 95% confidence with two experienced observers. Statistical analysis was performed using Stata/IC version 12.1 (StataCorp, College Station, TC, USA) and a p value < 0.05 was considered statistically significant.Introduction
Method
Surgeons, commissioners and patients are increasingly seeking more in depth details on outcomes of total ankle replacement (TAR). We set out to perform a detailed and up to date meta-analysis of the outcomes of TAR, with a focus on PROMS. We searched MEDLINE, Cochrane, EMBASE, CINAHL and the Science Citation Index databases using the terms “total”; “ankle”; “arthroplasty” or “replacement” to April 2012. We included all languages; series with greater than 20 TAR; minimum 2 years follow-up. We excluded papers on revisions; prostheses no longer marketed; and kin studies. We worked with the Cochrane Collaboration to adopt their methodology including the creation of a risk profile assessing all forms of bias.Introduction
Methods
The focus on evidence-based medicine has led to calls for increased levels of evidence in surgical journals. The purpose of the present study was to review the levels of evidence in articles published in the foot and ankle literature and to assess changes in the level of evidence over a decade. All articles from the years 2000 and 2010 in Foot and Ankle International, Foot and Ankle Surgery, and all foot and ankle articles from JBJS A and JBJS B were analysed. Animal, cadaveric, basic science, editorials, surveys, letters to Editor and correspondence were excluded. Articles were ranked by a five-point level of evidence scale, according to guidelines from the Centre for Evidence Based Medicine.Background
Methods
