Department of Orthopaedic Surgery, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen.
Acta Orthop. 2010 Apr;81(2):171-7. doi: 10.3109/17453671003635843.
Aseptic implant loosening and periprosthetic bone loss are major problems after total hip arthroplasty (THA). We present an in vivo method of computed tomography (CT) assisted osteodensitometry after THA that differentiates between cortical and cancellous bone density (BD) and area around the femoral component.
Cortical and cancellous periprosthetic femoral BD (mg CaHA/mL), area (mm(2)) and contact area between the prothesis and cortical bone were determined prospectively in 31 patients 10 days, 1 year, and 6 years after uncemented THA (mean age at implantation: 55 years) using CT-osteodensitometry.
6 years postoperatively, cancellous BD had decreased by as much as 41% and cortical BD by up to 27% at the metaphyseal portion of the femur; this decrease was progressive between the 1-year and 6-year examinations. Mild cortical hypertrophy was observed along the entire length of the diaphysis. No statistically significant changes in cortical BD were observed along the diaphysis of the stem.
Periprosthetic CT-assisted osteodensitometry has the technical ability to discriminate between cortical and cancellous bone structures with respect to strain-adapted remodeling. Continuous loss of cortical and cancellous BD at the femoral metaphysis, a homeostatic cortical strain configuration, and mild cortical hypertrophy along the diaphysis suggest a diaphyseal fixation of the implanted stem. CT-assisted osteodensitometry has the potential to become an effective instrument for quality control in THA by means of in vivo determination of periprosthetic BD, which may be a causal factor in implant loosening after THA.
无菌性植入物松动和假体周围骨丢失是全髋关节置换术（THA）后的主要问题。我们提出了一种在活体条件下通过计算机断层扫描（CT）辅助骨密度测量来检测 THA 后皮质骨和松质骨密度（BD）以及股骨假体周围区域的方法。
前瞻性地对 31 例患者（平均植入年龄为 55 岁）在 THA 后 10 天、1 年和 6 年时使用 CT 骨密度仪测量皮质骨和假体周围股骨的骨密度（mg CaHA/mL）、面积（mm(2))和假体与皮质骨之间的接触面积。
术后 6 年，股骨近端松质骨 BD 减少了多达 41%，皮质骨 BD 减少了多达 27%；这种减少在 1 年和 6 年检查之间是逐渐发生的。在骨干的整个长度上观察到轻微的皮质骨增生。在干骺端的骨密度没有明显的变化。
假体周围 CT 辅助骨密度测量具有区分皮质骨和松质骨结构的技术能力，与应变适应的重塑有关。股骨近端皮质骨和松质骨 BD 的持续丢失、皮质骨的平衡应变构型以及骨干的轻微皮质骨增生提示植入物的骨干固定良好。CT 辅助骨密度测量有可能通过活体测定假体周围的骨密度成为 THA 质量控制的有效手段，因为假体周围的骨密度可能是 THA 后植入物松动的一个因果因素。
