Pseudotumors have been reported following metal-on-metal total hip arthroplasty (THA); however, the natural history and longitudinal imaging findings of pseudotumors have yet to be fully analyzed. Our hypothesis was that pseudotumor size might change over time following metal-on-metal THA. This hypothesis was studied longitudinally using magnetic resonance imaging (MRI). Screening for pseudotumors was performed using MRI after large-diameter metal-on-metal THA. Initial MRI was conducted at a mean of 36 months postoperatively. Follow-up MRI was performed at a mean of 20 months after the detection of 24 pseudotumors in 20 asymptomatic patients. Pseudotumors were classified as cystic, solid, and mixed types. Fourteen hips were characterized as cystic type and 10 hips were defined as mixed type. There were three men and 17 women with a mean age of 63 years. Pseudotumor size was determined on MRI by manually outlining the greatest size of the mass. Serum cobalt and chromium ion levels were measured in nine patients with unilateral THA at the time of MRI. Statistical analysis was performed using the Kruskal-Wallis test and chi square test to compare age, gender, BMI, head diameter, cup inclination, cup anteversion, and pseudotumor type among changes of pseudotumor size. We compared the pseudotumor size for the three groups (increase in size, no change, decrease in size) using Kruskal-Wallis test and Mann-Whitney U test. Wilcoxon signed-rank test was used to compare median serum metal ion levels over time. A p value < 0.05 was considered significant. This study was approved by the ethics committee of our institution, and all patients provided informed consent.Introduction
Materials and Methods
Salubrinal is a synthetic agent that elevates phosphorylation
of eukaryotic translation initiation factor 2 alpha (eIF2α) and
alleviates stress to the endoplasmic reticulum. Previously, we reported
that in chondrocytes, Salubrinal attenuates expression and activity
of matrix metalloproteinase 13 (MMP13) through downregulating nuclear
factor kappa B (NFκB) signalling. We herein examine whether Salubrinal
prevents the degradation of articular cartilage in a mouse model
of osteoarthritis (OA). OA was surgically induced in the left knee of female mice. Animal
groups included age-matched sham control, OA placebo, and OA treated
with Salubrinal or Guanabenz. Three weeks after the induction of
OA, immunoblotting was performed for NFκB p65 and p-NFκB p65. At
three and six weeks, the femora and tibiae were isolated and the sagittal
sections were stained with Safranin O.Objectives
Methods
