Serum metal level analysis and implant retrieval analysis both contribute to the understanding of ALTR. Serum metal levels generally are elevated in the presence of ALTR but should not be used in isolation for clinical decision-making. Many but not all patients with ALTR, including those with pseudotumors, demonstrate high wear, but more data and more systematic descriptions of the histopathology are needed to define the amount of wear that induces adverse reactions.

Abstract:The lubrication of the cartilaginous structures in human joints is provided by a fluid from a specialized layer of cells at the surface of a delicate tissue called the synovial lining. Little is known about the characteristics of the fluids produced after a joint arthroplasty procedure. A literature review was carried out to identify papers that characterized the synovial lining and the synovial fluids formed after total hip or knee arthroplasty. Five papers about synovial lining histology and six papers about the lubricating properties of the fluids were identified. The cells making up the re-formed synovial lining, as well as the lining of interface membranes, were similar to the typical Type A and B synoviocytes of normal joints. The synovial fluids around joint replacement devices were typically lower in viscosity than pre-arthroplasty fluids but the protein concentration and phospholipid concentrations tended to be comparable, suggesting that the lining tissue function was preserved after arthroplasty. The widespread, long-term success of joint arthroplasty suggests that the lubricant formed from implanted joint synovium is adequate for good clinical performance in the majority of joints. The role the fluid plays in component wear or failure is a topic for future study. OPEN ACCESSLubricants 2015, 3 395

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BackgroundMany treatment decisions in children’s Orthopaedics are based on age. This study determined whether a discrepancy between chronological age (CA) and skeletal age (SA) is dependent on BMI and if overweight or obese children would have an advanced SA.Materials and Methods120 children between ages 8-17 with an adequate hand radiograph and a correlating BMI were enrolled by retrospective chart review. Stratification based on age, sex, ethnicity, and BMI percentile was performed. For each age group, 6 males and 6 females were selected with 50% of each group having an elevated BMI. Two blinded physicians independently evaluated hand radiographs and recorded the SA. Statistical analyses evaluated inter-rater reliability and any discrepancy between groups.ResultsThe final statistical analysis included 96 children. The Intraclass Correlation Coefficient for SA determined by the two reviewers was excellent at 0.95. A difference of 13 months was found between CA and SA in the elevated BMI cohort versus the non-elevated BMI cohort, (p<0.001). No significant difference was seen between CA and SA for the non-elevated cohort (p=0.72), while matching for age and sex. ConclusionChronological age and skeletal age are not always equivalent especially in pediatric patients who are overweight or obese.