Improvement of bone‐tendon fixation by porous titanium interference screw: A rabbit animal model

Abstract

The interference screw is a widely used fixation device in the anterior cruciate ligament (ACL) reconstruction surgeries. Despite the generally satisfactory results, problems of using interference screws were reported. By using additive manufacturing (AM) technology, we developed an innovative titanium alloy (Ti Al V) interference screw with rough surface and inter-connected porous structure designs to improve the bone-tendon fixation. An innovative Ti Al V interference screws were manufactured by AM technology. In vitro mechanical tests were performed to validate its mechanical properties. Twenty-seven New Zealand white rabbits were randomly divided into control and AM screw groups for biomechanical analyses and histological analysis at 4, 8, and 12 weeks postoperatively; while micro-CT analysis was performed at 12 weeks postoperatively. The biomechanical tests showed that the ultimate failure load in the AM interference screw group was significantly higher than that in the control group at all tested periods. These results were also compatible with the findings of micro-CT and histological analyses. In micro-CT analysis, the bone-screw gap was larger in the control group; while for the additive manufactured screw, the screw and bone growth was in close contact. In histological study, the bone-screw gaps were wider in the control group and were almost invisible in the AM screw group. The innovative AM interference screws with surface roughness and inter-connected porous architectures demonstrated better bone-tendon-implant integration, and resulted in stronger biomechanical characteristics when compared to traditional screws. These advantages can be transferred to future interference screw designs to improve their clinical performance. The AM interference screw could improve graft fixation and eventually result in better biomechanical performance of the bone-tendon-screw construct. The innovative AM interference screws can be transferred to future interference screw designs to improve the performance of implants. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2633-2640, 2018.

Three-Dimensional Printed Porous Titanium Screw with Bioactive Surface Modification for Bone–Tendon Healing: A Rabbit Animal Model

“…Before the animal study, a power analysis was performed to calculate the number of animals needed to prevent type II errors. In our previous study, micro-CT revealed the bone volume fraction (BV/TV) to be 39.0 ± 6.7 % for the experimental tibia [26]. Six specimens per group achieved a power of 0.80 with α = 0.05.…”

“…Furthermore, AM technology provides greater customizability, speed, and accuracy through computer-aided design. In our previous study, we illustrated how a porous Ti interference screw produced using AM technology could improve tibial graft fixation and enhance the biomechanical performance of the bone-tendon-screw construct [26]. We proposed that by using surface modification technology, we could develop a novel interference screw with appropriate structural porosity and surface reactivity, which would improve graft fixation and enhance biomechanical performance.…”

Biocompatibility and Biological Performance Evaluation of Additive-Manufactured Bioabsorbable Iron-Based Porous Suture Anchor in a Rabbit Model

“…Increasing surface area and incorporation of porous structures into an iron-based biodegradable material can accelerate its degradation rate [ 5 , 20 , 21 , 22 , 23 ]. Our control group suture anchors were famous for its open architecture in appearance that had the higher surface area [ 24 , 25 ].…”

Effect of Pore Size of Porous-Structured Titanium Implants on Tendon Ingrowth

“…The solid part on top of the specimen (Figures 1(a) – 1(d) and Figure S1 ) was designed to normalize the fixation area in the mechanical tests. Second, compared with fixation with screws, the in-tendon model reduced the influence of bone marrow-derived stem cells [ 59 , 60 ]. Third, a simpler surgical procedure reduced the operation time and bleeding, and the interface was cleaned due to its low blood supply, similar to tendons.…”