Effects of Ti2448 half-pin with low elastic modulus on pin loosening in unilateral external fixation

Abstract

The objective of this study was to compare the benefits of titanium 2448 (Ti2448) half-pin and titanium-6 aluminium-4 vanadium (TAV) half-pin on reducing pin loosening during external fracture fixation. Although having similar strength, Ti2448 half-pin had even lower elastic modules (33 GPa) when compared with TAV half-pin (110 GPa), which was similar to that of cortical bone (20 GPa). In the external fixation of tibial model fractures and canine cadaveric tibia fractures, Ti2448 half-pin had greater recoverable deformation and less stress concentration at the pin-bone interface in compression, torsion, and four-points bending test. Then, tibial fractures were created in 24 dogs and stabilized with four half-pins of either Ti2448 or TAV in each animal. At 4 and 8 weeks postoperatively, fracture healing and pin loosening was assessed by radiographic grading scale. The scores of Ti2448 group were significantly higher than those of TAV group. Micro-CT analysis also indicated larger quantity and higher quality of newly formed bone at pin-bone interface in Ti2448 group. Histology observation showed the newly formed bone integrated well into the threads of Ti2448 half-pins. In contrast, there was a layer of necrotic tissue between the bone tissue and TAV half-pin at pin-bone interface in TAV group. The extraction torque values of Ti2448 half-pins near the fracture line were significantly higher than those TAV pins. In conclusion, the Ti2448 half-pin with low elastic modulus could enhance osseointegration and reduce pin loosening when compared with TAV half-pin. It is a promising biomaterial for constructing external fixation system in clinical application.

Three-Dimensionally Printed Ti2448 With Low Stiffness Enhanced Angiogenesis and Osteogenesis by Regulating Macrophage Polarization via Piezo1/YAP Signaling Axis

“…Our previous studies demonstrated that a Ti2448 half-pin could enhance osseointegration and reduce pin loosening in the external fixation of tibial fractures in dogs in vitro and in vivo ( Zheng et al, 2011 ). In this study, we also found that Ti2448 exhibited better angiogenesis and osteogenesis than Ti6Al4V in a rabbit femoral condylar defect model.…”

Effects of the surface characteristics of nanoporous titanium oxide films on Ti-24Nb-4Zr-8Sn alloy on the initial adhesion of osteoblast-like MG-63 cells

“…Therefore, novel titanium alloys containing non-toxic and non-allergic elements, including Nb, Ta, Zr, Mo and Sn, have been designed and constructed for biomedical applications (7). The novel β-type titanium alloy Ti-24Nb-4Zr-8Sn (Ti2448) has attracted considerable attention due to its high strength, high fatigue resistance and a low elastic modulus (8). An in vivo study of Ti2448 in New Zealand white rabbits demonstrated that the low elastic modulus of Ti2448 leads to significant improvements in new bone formation following a tibial shaft fracture compared with a Ti-6Al-4V alloy (9).…”

An engineering review of external fixators

“…Presently, the commonly used pin materials are stainless steel and the titanium alloy Ti-6Al-4 V. The main reason for the choice of these materials is their higher strength. However, in general, both steel and titanium possess high elastic moduli, former in the range of 200 GPa and the latter in the order of 100 GPa [107] . These values are significantly higher than the elastic modulus of bones which is generally in the range of 20 GPa [107] .…”

“…However, in general, both steel and titanium possess high elastic moduli, former in the range of 200 GPa and the latter in the order of 100 GPa [107] . These values are significantly higher than the elastic modulus of bones which is generally in the range of 20 GPa [107] . Hence, this apparent disparity between the elastic moduli of the pin material and the bone can lead to stress concentrations at the pin-joint interface due to lower recoverable deformation.…”

“…Zheng et al. [107] compared the performance of pins in a unilateral EF, where the pins were made of two titanium alloys, namely Ti2448 and Ti 6 Al 4 V. The former has a comparable or a slightly higher strength, while possessing a significantly lower elastic modulus (by 70%). However, the elastic modulus of Ti2448 (33 GPa) is closer to the elastic modulus of that of a cortical bone (20 GPa).…”