Patients with osteoarthritis undergoing shoulder arthroplasty may suffer from osteoporosis. The purpose of this study was to determine whether computed tomography (CT)-derived Hounsfield unit (HU) measurements correlate with bone mineral density (BMD) and whether these data could predict implant size and fixation choice.
The study analyzed preoperative dual energy x-ray absorptiometry and shoulder CT scans for 230 patients who underwent total shoulder arthroplasty. Hip BMD and T scores and HU attenuation in the humerus were correlated. HU cutoff values were developed to aid in differentiating patients whose BMD values were within normal reference ranges from patients with osteopenia or osteoporosis. Risk factors associated with low BMD were correlated, and the effect of BMD on humeral stem size, and fixation method was investigated.
Significant correlations between HU and hip BMD and T score were identified (P < .001). HU value ranges were identified that may alert the surgeon of metabolic bone disease. Significant correlation (P < 0.05) was found between low BMD and certain osteoporosis risk factors. Age at time of surgery was a predictor of cemented stem fixation (P = .024). Patients with a lower BMD were statistically more likely to receive a larger-diameter humeral stem (P = .016).
Level III, Study of Nonconsecutive Patients, Diagnostic Study.
Orthopedic surgeons may be able to use data obtained from shoulder CT scans to predict the need for larger stem size or cement fixation during shoulder arthroplasty. In combination with the risk factor profile, these data may be useful in predicting the need for an osteoporosis workup and treatment.