Peri-prosthetic Bone Remodeling of Hydroxyapatite-coated Compaction Short Stem was Not Affected by Stem Alignment

Abstract Background: We aimed to investigate the relationship between stem insertion alignment and postoperative bone mineral density (BMD) changes in patients with full hydroxyapatite-coated (HA) compaction short stem and short tapered-wedge stem. Methods: This retrospective cohort study enrolled 115 consecutive patients (115 joints) undergoing total hip arthroplasty (THA) using the full HA compaction short (n=59) and short tapered-wedge (n=56) stems. Stem alignment including anteversion, valgus, and anterior tilt were measured by 3D-template using computed tomography (CT) data. Post-operative peri-prosthetic BMD was measured by dual-energy X-ray absorptiometry (DEXA). The relationship between stem alignment and BMD changes in the stems were analyzed. Results: Both groups showed similar patterns of peri-prosthetic BMD changes. Stem insertion alignments of anteversion, valgus, and anterior tilt were different between the two types of stems. Stem alignment of valgus and anterior tilt did not affect peri-prosthetic BMD in either type of stem. An absolute anteversion difference between stem anteversion and original canal anteversion caused significant peri-prosthetic BMD loss in Gruen zones 1 and 7 in the tapered-wedge stem. However, stem alignment of absolute anteversion difference did not affect BMD changes in the HA compaction stem. Conclusion: Peri-prosthetic bone remodeling remained unaffected by stem alignment after THA with the new short full HA compaction stem.