The association between bone mineral denity adjacent to acetabular implants, as measured by quanitative computed tomography (QCT), at least 2 years post Total Hip Arthoplasty (THA) surgery and mesechymal stem cell assays, obtained at time of surgery, will evaluate if stem cells can predict orthopaedic surgical outcomes.

Detailed Description:

Subjects who have undergone a THA and who previously consented to "Stem Cell Quality Assays: Correlation with Aging/Health" study which used excess bone marrow and blood samples to complete stem cell assay labs will be invited back at least 2 years post THA to complete bilateral hip x-rays, if not already completed as part of routine medical follow up plus a QCT bone density testing and to complete a questionnaire regarding smoking, alcohol and exercise history along with recording BMIs.

Bone mineral density adjacent to acetabular implants will be evaluated using QCT which can show early bony changes, which can provide information about the quality of implant fixation and surrounding bone adaption. X-rays will evaluate component loosening, wear, alignmet and osteolytis. Patient characteristics will be summarized using descriptive statistics. Spearman correlation coefficients will be used to assess the association of Mesenchymal stem cell assays and bone density findings.