Wölfle-Roos Julia, Katmer Amet B, Fiedler J, Michels H, Kappelt G, Ignatius A, Dürselen L, Reichel H, Brenner Rolf
Department of Orthopaedic Surgery, Ulm University, 89081 Ulm, Germany.
Department of Orthopaedic Surgery, Division for Biochemistry of Joint and Connective Tissue Diseases, Ulm University, 89081 Ulm, Germany.
Materials (Basel). 2020 Apr 3;13(7):1670. doi: 10.3390/ma13071670.
Uncemented implants are still associated with several major challenges, especially with regard to their manufacturing and their osseointegration. In this study, a novel manufacturing technique-an optimized form of precision casting-and a novel surface modification to promote osseointegration-calcium and phosphorus ion implantation into the implant surface-were tested in vivo.
Cylindrical Ti6Al4V implants were inserted bilaterally into the tibia of 110 rats. We compared two generations of cast Ti6Al4V implants (CAST 1st GEN, n = 22, and CAST 2nd GEN, n = 22) as well as cast 2nd GEN Ti6Al4V implants with calcium (CAST + CA, n = 22) and phosphorus (CAST + P, n = 22) ion implantation to standard machined Ti6Al4V implants (control, n = 22). After 4 and 12 weeks, maximal pull-out force and bone-to-implant contact rate (BIC) were measured and compared between all five groups.
There was no significant difference between all five groups after 4 weeks or 12 weeks with regard to pull-out force ( > 0.05, Kruskal Wallis test). Histomorphometric analysis showed no significant difference of BIC after 4 weeks ( > 0.05, Kruskal-Wallis test), whereas there was a trend towards a higher BIC in the CAST + P group (54.8% ± 15.2%), especially compared to the control group (38.6% ± 12.8%) after 12 weeks ( = 0.053, Kruskal-Wallis test).
In this study, we found no indication of inferiority of Ti6Al4V implants cast with the optimized centrifugal precision casting technique of the second generation compared to standard Ti6Al4V implants. As the employed manufacturing process holds considerable economic potential, mainly due to a significantly decreased material demand per implant by casting near net-shape instead of milling away most of the starting ingot, its application in manufacturing uncemented implants seems promising. However, no significant advantages of calcium or phosphorus ion implantation could be observed in this study. Due to the promising results of ion implantation in previous in vitro and in vivo studies, further in vivo studies with different ion implantation conditions should be considered.
非骨水泥型植入物仍然面临着几个主要挑战，特别是在其制造和骨整合方面。在本研究中，一种新型制造技术——精密铸造的优化形式——以及一种促进骨整合的新型表面改性方法——将钙和磷离子植入植入物表面——在体内进行了测试。
将圆柱形Ti6Al4V植入物双侧植入110只大鼠的胫骨中。我们比较了两代铸造Ti6Al4V植入物（第一代铸造，n = 22，第二代铸造，n = 22），以及第二代铸造Ti6Al4V植入物分别进行钙（铸造+钙，n = 22）和磷（铸造+磷，n = 22）离子植入后的情况，与标准加工的Ti6Al4V植入物（对照组，n = 22）进行对比。4周和12周后，测量并比较了所有五组的最大拔出力和骨-植入物接触率（BIC）。
4周或12周后，所有五组在拔出力方面无显著差异（Kruskal Wallis检验，P>0.05）。组织形态计量学分析显示，4周后BIC无显著差异（Kruskal-Wallis检验，P>0.05），而在12周后，铸造+磷组的BIC有升高趋势（54.8%±15.2%），尤其是与对照组（38.6%±12.8%）相比（Kruskal-Wallis检验，P = 0.053）。
在本研究中，我们发现与标准Ti6Al4V植入物相比，采用第二代优化离心精密铸造技术铸造的Ti6Al4V植入物并无劣势迹象。由于所采用的制造工艺具有可观的经济潜力，主要是因为通过近净形铸造而非铣削大部分起始铸锭，每个植入物的材料需求显著降低，其在制造非骨水泥型植入物中的应用似乎很有前景。然而，在本研究中未观察到钙或磷离子植入有显著优势。鉴于先前体外和体内研究中离子植入取得的有前景的结果，应考虑进行不同离子植入条件下的进一步体内研究。
