Accuracy of acetabular cup placement using CT-based navigation in total hip arthroplasty: Comparison between obese and non-obese patients

BACKGROUND

In obese patients, malpositioning of the acetabular cup increases the risk of dislocation in total hip arthroplasty (THA). The aim of this study was to determine whether obesity affects the accuracy of acetabular cup positioning using a computed tomography (CT)-based navigation system.

METHODS

We retrospectively evaluated 226 consecutive patients who underwent cementless primary THAs assisted by the CT-based hip navigation system. We divided the patients into three groups according to body mass index (BMI) and examined the difference between preoperative planning and postoperative implantation angles from CT data.

RESULTS

There was no significant correlation between BMI and both inclination and anteversion differences (R = 0.028 and R = 0.045, respectively). There were no significant differences among the BMI < 25, 25 ≦ BMI < 30, and BMI ≧ 30 groups (p value: 0.725, 0.934, respectively); between the BMI < 25 and BMI ≧ 25 groups (p value: 0.542, 0.697, respectively); and between the BMI < 30 and BMI ≧ 30 groups with regard to inclination and anteversion (p value: 0.859, 0.456, respectively). Moreover, similar findings were observed with regard to the distance between the preoperative planning and postoperative cup positioning for the transverse, anteroposterior, and craniocaudal axes of the pelvis.

CONCLUSION

We found that the accuracy of acetabular cup placement using CT based-navigation in THA was not affected in obese patients. Therefore, THAs with a CT-based navigation system are considered useful in obese patients.

Molecular cloning and expression of Caenorhabditis elegans ERp57-homologue with transglutaminase activity

Formation of cross-linking between proteins via a gamma-glutamyl-epsilon-lysine residue is an important process in many biological phenomena including apoptosis. Formation of this linkage is catalyzed by the enzyme transglutaminase, which is widely distributed from bacteria to the animal kingdom. The simple multi-cellular organism Caenorhabditis elegans also possesses transglutaminase activity associated with apoptosis [Madi, A. et al. (1998) Eur. J. Biochem. 253, 583-590], but no gene with significant homology to vertebrate or bacterial transglutaminases has been found in the C. elegans genome sequence database. On the other hand, protein disulfide isomerases were recently recognized as a new family of transglutaminases [Chandrashekar, R. et al. (1998) Proc. Natl. Acad. Sci. USA 95, 531-536]. To identify the molecule with transglutaminase activity in C. elegans, we isolated from C. elegans a gene homologous to ERp57, which encodes a protein disulfide isomerase, expressed it in recombinant form, and characterized the transglutaminase and protein disulfide isomerase activities of the resultant protein. The C. elegans ERp57 protein had both enzyme activities, and the transglutaminase activity had similar characteristics to the activity in lysate of the whole worm. These results suggested that the ERp57 homologue was one of the substances with transglutaminase activity in C. elegans.