title: 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.
authors.affiliation: Department of Orthopedic Oncology, Xi-jing Hospital, The Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zheng
authors.forename: Xiaokang
authors.initials: X
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Fu
authors.forename: Xiangli
authors.initials: X
authors.lastname: Fan
authors.forename: Pan
authors.initials: P
authors.lastname: Wang
authors.forename: Yulin
authors.initials: Y
authors.lastname: Hao
authors.forename: Shujun
authors.initials: S
authors.lastname: Li
authors.forename: Hongbin
authors.initials: H
authors.lastname: Fan
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guo
mesh_terms: D000818:Animals; D001858:Bone Nails; D003198:Computer Simulation; D004285:Dogs; D055119:Elastic Modulus / Q000187:drug effects / Q000502:physiology*; D016267:External Fixators / Q000009:adverse effects; D005592:Fracture Fixation / Q000009:adverse effects; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods; D011475:Prosthesis Failure / Q000187:drug effects; D013314:Stress, Mechanical; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*; D055114:X-Ray Microtomography
chemical_list: D014025:Titanium