Inoue Daisuke, Kabata Tamon, Maeda Toru, Kajino Yoshitomo, Fujita Kenji, Hasegawa Kazuhiro, Yamamoto Takashi, Takagi Tomoharu, Ohmori Takaaki, Tsuchiya Hiroyuki
Department of Orthopaedic Surgery, Graduate School of Medical Science, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa, 920-8641, Japan.
Eur J Orthop Surg Traumatol. 2015 Dec;25(8):1293-300. doi: 10.1007/s00590-015-1705-3. Epub 2015 Nov 5.
It would be ideal if surgeons could precisely confirm whether the planned femoral component achieves the best fit and fill of implant and femur. However, the cortico-cancellous interfaces can be difficult to standardize using plain radiography, and therefore, determining the contact state is a subjective decision by the examiner. Few reports have described the use of CT-based three-dimensional templating software to quantify the contact state of stem and femur in detail. The purpose of this study was to use three-dimensional templating software to quantify the implant-femur contact state and develop a technique to analyze the initial fixation pattern of a cementless femoral stem.
We conducted a retrospective review of 55 hips in 53 patients using a short proximal fit-and-fill anatomical stem (APS Natural-Hip™ System). All femurs were examined by density mapping which can visualize and digitize the contact state. We evaluated the contact state of implant and femur by using density mapping.
The varus group (cases that had changed varus 2° by 3 months after surgery) consisted of 11 hips. The varus group showed no significant difference with regard to cortical contact in the proximal medial portion (Gruen 7), but the contact area in the distal portion (Gruen 3 and Gruen 5) was significantly lower than that of non-varus group. Density mapping showed that the stem only has to be press-fit to the medial calcar, but also must fill the distal portion of the implant in order to achieve the ideal contact state.
Our results indicated that quantifying the contact state of implant and femur by using density mapping is a useful technique to accurately analyze the fixation pattern of a cementless femoral stem.
如果外科医生能够精确确认计划使用的股骨假体是否实现了植入物与股骨的最佳匹配和填充，那将是非常理想的。然而，使用普通X线摄影很难使皮质-松质骨界面标准化，因此，确定接触状态是检查者的主观判断。很少有报告描述使用基于CT的三维模板软件来详细量化柄与股骨的接触状态。本研究的目的是使用三维模板软件量化植入物与股骨的接触状态，并开发一种技术来分析非骨水泥型股骨干的初始固定模式。
我们对53例患者的55髋进行了回顾性研究，使用的是短近端匹配和填充解剖型柄（APS Natural-Hip™ 系统）。所有股骨均通过密度映射检查，该方法可以可视化并数字化接触状态。我们使用密度映射评估植入物与股骨的接触状态。
内翻组（术后3个月内翻角度改变2°的病例）包括11髋。内翻组在近端内侧部分（Gruen 7区）的皮质接触方面无显著差异，但远端部分（Gruen 3区和Gruen 5区）的接触面积显著低于非内翻组。密度映射显示，柄不仅必须压配到内侧距，还必须填充植入物的远端部分，以实现理想的接触状态。
我们的结果表明，使用密度映射量化植入物与股骨的接触状态是一种准确分析非骨水泥型股骨干固定模式的有用技术。
