A 5-7 year in vivo study of high-strength hydroxyapatite/poly(L-lactide) composite rods for the internal fixation of bone fractures.
The biocompatibility and biodegradation of hydroxyapatite (HA)/poly(L-lactide) (PLLA) composite bone implant rods were studied using two types of HA particles as reinforcing fillers, uncalcined-HA (u-HA) or calcined-HA (c-HA). Composite rods of u-HA/PLLA and c-HA/PLLA were implanted into the distal femurs of 25 rabbits. Four of these rabbits lived for more than 5 years after implantation, with one living for 7 years 4 months. Samples were retrieved after the rabbits died naturally and specimens were examined by light microscopy and scanning electron microscopy (SEM). For u-HA/PLLA, the shrinkage of the rods progressed further after 4 years, and some were almost completely resorbed. We could not find traces of the rod in some sections from more than 6 years. Remodeled bone encircled the residual material, and trabecular bone bonded directly to the rod was found toward the center. For u-HA/PLLA 30%, results were similar to u-HA/PLLA 40%, and the cross-sectional area had decreased by 4.0% at over 7 years. Most of the PLLA had been released from the rods. Neither obvious osteolytic nor osteoarthritic changes were found after 4 years.
Hasegawa
Shin
S
Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. shinhase@kuhp.kyoto-u.ac.jp
Ishii
Shinsuke
S
Tamura
Jiro
J
Furukawa
Taizo
T
Neo
Masashi
M
Matsusue
Yoshitaka
Y
Shikinami
Yasuo
Y
Okuno
Masaki
M
Nakamura
Takashi
T
D000818:Animals; D018786:Bone Substitutes; D017886:Durapatite; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D016268:Internal Fixators; D008297:Male; D011091:Polyesters; D019736:Prostheses and Implants; D011817:Rabbits; D013997:Time Factors
D018786:Bone Substitutes; D011091:Polyesters; C033616:poly(lactide); D017886:Durapatite