Association Between Bone Mineral Density Around the Stem, Morphology of the Proximal Femur, and Effects of Osteoporosis Treatment in Patients with Femoral Neck Fracture

<b>Background/Objectives:</b> The aim of this study was to evaluate changes in bone mineral density (BMD) around the stem in elderly patients with femoral neck fractures who underwent hemiarthroplasty using a collared and full hydroxyapatite coated cementless stem, as assessed using the Dorr classification and with anti-osteoporosis drug intervention. <b>Methods:</b> This study followed 85 older patients with femoral neck fractures classified by Dorr’s classification. We measured their BMD around the stem using dual-energy X-ray absorptiometry according to Gruen 7 zones classification and clinical scores. We compared the rate of BMD change based on Dorr’s classification and clinical scores. We also investigated the effect of osteoporosis treatment interventions on the rate of BMD change. The study followed up with the patients for one year after surgery. <b>Results:</b> After excluding patients with missing data, 40 patients were included in the analysis. The rate of change in BMD in zone 2 was significantly reduced in Dorr type C compared to Dorr type B. Clinical scores did not significantly differ between the three groups. Regarding the association between osteoporosis treatment and the rate of BMD change, the pre-injury intervention group had a significantly suppressed decline in the rate of BMD change in zones 1 and 7 compared to the post-injury intervention and no-intervention groups. <b>Conclusions:</b> Careful follow-up examination is crucial when performing hemiarthroplasty in patients with Dorr type C femoral neck fractures because the rate of BMD change may decline postoperatively. Pre-injury osteoporosis intervention therapy may suppress BMD loss around the stem.