Fixation of distal femoral osteotomies with self-reinforced poly(L/DL)lactide 70:30 and self-reinforced poly(L/DL)lactide 70: 30/bioactive glass composite rods. an experimental study on rabbits.
Two self-reinforced poly(L/DL)lactide 70:30 or self-reinforced poly (L/DL)lactide 70:30/ bioactive glass (SR-P(L/DL)LA/bioactive glass) composite rods (2 mm x 40 mm) were implanted into the dorsal subcutaneous tissue and osteotomies of the distal femur were fixed with these rods (2 mm x 26 mm) in 36 rabbits. The follow-up times varied from 3 to 100 weeks. After the animals were killed, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic and oxytetracycline-fluorescence studies of the osteotomized and intact control femora were performed. After 12 weeks the SR-P(L/DL)LA rods had fragmented into pieces and the mechanical properties could not be measured. The SR-P(L/DL)LA/bioactive glass rods lost their mechanical properties slower, and at 24 weeks the bending strength had decreased by 39% and the shear strength by 50%. After that the mechanical properties of the SR-P(L/DL)LA/bioactive glass rods could not be measured. All osteotomies healed well, and no gross signs of inflammatory reactions were observed. One slight displacement was seen in the three-week follow-up group with SR-P(L/DL)LA rods. Signs of resorption of the implants were seen after 48 weeks in the SR-P(L/DL)LA group and after 24 weeks in the SR-P(L/DL)LA/bioactive glass group. The SR-P(L/DL)LA/bioactive glass rods were almost totally resorbed from the bone at 100 weeks. The present investigation showed that the mechanical strength and fixation properties of the SR-P(L/DL)LA and the SR-P(L/DL)LA/bioactive glass composite rods are suitable for fixation of cancellous bone osteotomies in rabbits.
Pyhältö
Tuomo
T
Department of Orthopaedics and Traumatology, Helsinki University Central Hospital and University of Helsinki, Finland. tuomo.pyhalto@medone.fi
Lapinsuo
Matti
M
Pätiälä
Hannu
H
Niiranen
Henna
H
Törmälä
Pertti
P
Rokkanen
Pentti
P
D000818:Animals; D001673:Biodegradation, Environmental; D005269:Femur / Q000293:injuries / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000379:methods* / Q000592:standards; D005898:Glass; D007249:Inflammation; D016268:Internal Fixators / Q000592:standards*; D008422:Materials Testing; D019563:Mechanics; D010027:Osteotomy / Q000379:methods*; D011091:Polyesters / Q000627:therapeutic use*; D011817:Rabbits; D014945:Wound Healing
D011091:Polyesters; C033616:poly(lactide)