Limits...
The effects of nail rigidity on fracture healing in rats with osteoporosis.

Sha M, Guo Z, Fu J, Li J, Yuan CF, Shi L, Li SJ - Acta Orthop (2009)

Bottom Line: In the low-rigidity group, TV (ROI1) increased at 6 weeks, but BV (ROI1), BV (ROI2) were similar but maximum load increased.At 12 weeks, the maximum load and also BV (ROI1, ROI2) were increased in the low-rigidity group.The low-rigidity nail manufactured from Ti-24Nb-4Zr-7.9Sn showed better external callus formation, seemed to reduce effects of stress shielding, and reduced bone resorption better than the stiffer nail.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.

ABSTRACT

Background and purpose: Stress shielding from rigid internal fixation may lead to refracture after removal of the osteosynthesis material. We investigated the effect of a low-rigidity (Ti-24Nb-4Zr-7.9Sn) intramedullary nail regarding stress shielding and bone healing of osteoporotic fractures in the rat.

Methods: 40 female Sprague-Dawley rats, aged 3 months, were divided into the following groups: sham-operation (SHAM) (n = 10), ovariectomized (OVX) (n = 10) and OVX-fracture (n = 20). 10 SHAM rats and 10 OVX rats were killed after 12 weeks to provide biomechanical data. Ovariectomy was performed 12 weeks before fracturing both femurs in 20 rats. The left fracture was stabilized with a high-rigidity titanium alloy pin (Ti-6Al-4V; elastic modulus 110 GPa) and the right with a low-rigidity (Ti-24Nb-4Zr-7.9Sn; elastic modulus 33 GPa). The bony calluses were examined by micro-CT at 6 and 12 weeks after fracture, bone volume (BV) and total volume (TV) were determined at the callus region (ROI1) and the total femur (ROI2). Subsequently, the bones were tested mechanically by a three-point bending test.

Results: In the low-rigidity group, TV (ROI1) increased at 6 weeks, but BV (ROI1), BV (ROI2) were similar but maximum load increased. At 12 weeks, the maximum load and also BV (ROI1, ROI2) were increased in the low-rigidity group.

Interpretation: The low-rigidity nail manufactured from Ti-24Nb-4Zr-7.9Sn showed better external callus formation, seemed to reduce effects of stress shielding, and reduced bone resorption better than the stiffer nail. The low-rigidity nail was strong enough to maintain alignment of the fracture in the osteoporotic rat model without delayed union.

Show MeSH

Related in: MedlinePlus

Three-dimensional reconstruction at 12 weeks (with yellow region corresponding to ROI1). A. Low-rigidity group. B- High-rigidity group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2823242&req=5

Figure 0002: Three-dimensional reconstruction at 12 weeks (with yellow region corresponding to ROI1). A. Low-rigidity group. B- High-rigidity group.


The effects of nail rigidity on fracture healing in rats with osteoporosis.

Sha M, Guo Z, Fu J, Li J, Yuan CF, Shi L, Li SJ - Acta Orthop (2009)

Three-dimensional reconstruction at 12 weeks (with yellow region corresponding to ROI1). A. Low-rigidity group. B- High-rigidity group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823242&req=5

Figure 0002: Three-dimensional reconstruction at 12 weeks (with yellow region corresponding to ROI1). A. Low-rigidity group. B- High-rigidity group.
Bottom Line: In the low-rigidity group, TV (ROI1) increased at 6 weeks, but BV (ROI1), BV (ROI2) were similar but maximum load increased.At 12 weeks, the maximum load and also BV (ROI1, ROI2) were increased in the low-rigidity group.The low-rigidity nail manufactured from Ti-24Nb-4Zr-7.9Sn showed better external callus formation, seemed to reduce effects of stress shielding, and reduced bone resorption better than the stiffer nail.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.

ABSTRACT

Background and purpose: Stress shielding from rigid internal fixation may lead to refracture after removal of the osteosynthesis material. We investigated the effect of a low-rigidity (Ti-24Nb-4Zr-7.9Sn) intramedullary nail regarding stress shielding and bone healing of osteoporotic fractures in the rat.

Methods: 40 female Sprague-Dawley rats, aged 3 months, were divided into the following groups: sham-operation (SHAM) (n = 10), ovariectomized (OVX) (n = 10) and OVX-fracture (n = 20). 10 SHAM rats and 10 OVX rats were killed after 12 weeks to provide biomechanical data. Ovariectomy was performed 12 weeks before fracturing both femurs in 20 rats. The left fracture was stabilized with a high-rigidity titanium alloy pin (Ti-6Al-4V; elastic modulus 110 GPa) and the right with a low-rigidity (Ti-24Nb-4Zr-7.9Sn; elastic modulus 33 GPa). The bony calluses were examined by micro-CT at 6 and 12 weeks after fracture, bone volume (BV) and total volume (TV) were determined at the callus region (ROI1) and the total femur (ROI2). Subsequently, the bones were tested mechanically by a three-point bending test.

Results: In the low-rigidity group, TV (ROI1) increased at 6 weeks, but BV (ROI1), BV (ROI2) were similar but maximum load increased. At 12 weeks, the maximum load and also BV (ROI1, ROI2) were increased in the low-rigidity group.

Interpretation: The low-rigidity nail manufactured from Ti-24Nb-4Zr-7.9Sn showed better external callus formation, seemed to reduce effects of stress shielding, and reduced bone resorption better than the stiffer nail. The low-rigidity nail was strong enough to maintain alignment of the fracture in the osteoporotic rat model without delayed union.

Show MeSH
Related in: MedlinePlus