When following patients with metal-on-metal (MoM) hip replacements, current evidence suggests that orthopaedic surgeons should avoid reliance on any single investigative tool. In 2014, guidelines for stratifying patients with MoM hip replacement into groups of low, medium, and high risk of failure based on multiple criteria were published. However, such risk stratification guidelines can be difficult to interpret due to the numerous risk factors related to MoM hip replacements. This is especially true for patients with various (high and low) risk levels for different criteria within the guidelines. The first purpose of this study was to assess if a scoring system can be applied to the current MoM guidelines. The second purpose was to test, using this scoring system, how the contemporary guidelines would classify a cohort of patients with a recalled MoM hip replacement system. The study population consisted of 1301 patients (1434 hips) enrolled from September 2012 to June 2015 in a multicenter follow-up study of a recalled MoM hip replacement system at a mean of 6.2 (range 2.4 – 11.2) years from index surgery. Eleven required scoring criteria were determined based on existing follow-up algorithm recommendations and consisted of patient factors, symptoms, clinical status, implant type, metal ion levels, and radiographic imaging results. Criteria considered ‘low’ risk were given 1 point, 2 points for ‘moderate’ risk, and 3 points for the ‘high’ risk group. Forward stepwise logistic regression was conducted to determine the minimum set of predictive variables for risk of revision and assign variable weights. The MoM risk score for each hip was then created by averaging the weighted values of each predictive variable.Introduction
Methods
Mechanically assisted crevice corrosion (MACC) in metal-on-polyethylene (MOP) total hip arthroplasty (THA) is of concern, but its prevalence, etiology and natural history are incompletely understood. From January 2003 to December 2012, 1356 consecutive THA surgeries using a titanium stem, cobalt chromium alloy femoral head, highly crosslinked polyethylene and a tantalum or titanium acetabular shell were performed. Patients were followed at 1 year, and 5 year intervals for surveillance, but also seen earlier if they had symptoms. Any patient with osteolysis or unexplained pain underwent exam, radiographs, CBC, ESR and CRP, as well as serum cobalt (Co) and chromium (Cr) level. MARS MRI was performed if the Co level was > 1 ppb.Introduction
Methods
The ASR™ Articular Surface Replacement and ASR™ XL Metal-on-Metal systems were recalled due to high revision rates at five years. A worldwide clinical follow-up of patients was initiated. This paper summarizes current findings in South Africa (SA) in comparison with those outside SA (OSA). Patients were followed annually, or until revision, from 10 clinical centers worldwide. Data collected includes demographic, surgical, radiographic, blood metal ion levels, and patient reported outcome measures (PROM).Introduction:
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