A case of juvenile idiopathic arthritis exhibiting repair of systemic bone erosion in response to continuation of MTX therapy after achievement of clinical remission.

We report a patient with rheumatoid factor-positive polyarthritis-type juvenile idiopathic arthritis (JIA) in whom clinical remission was achieved within 10 months after the start of methotrexate (MTX) therapy, and systemic repair of bone erosion was noted 8 months after clinical remission. These results indicate that even in cases of active JIA with the development of bone erosion, continuation of MTX therapy after the achievement of clinical remission can improve the prognosis, including repair of bone destruction.

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.

Long-term study of high-strength hydroxyapatite/poly(L-lactide) composite rods for the internal fixation of bone fractures: a 2-4-year follow-up study in rabbits.

Biodegradation of hydroxyapatite (HA)/poly(L-lactide)(PLLA) composite bone implant rods was studied with the use of 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 containing 30 or 40% (w/w) HA were implanted in the distal femur of 21 rabbits, and specimens were examined by light microscopy, scanning-electron microscopy (SEM), and transmission-electron microscopy (TEM) 2-4 years later. For u-HA/PLLA, trabecular bone bonding directly onto the rod was maintained for up to 2 years. By 3 years, surface collapse had begun, and the implants were shrinking. By 4 years, they had shrunk further, with complete bone encapsulation. The u-HA particles were small and needle shaped in the peripheries, and TEM confirmed their resorption. The cross-sectional area after 4 years decreased by 23.3+/-8.4%. The mean ratio of bony ingrowth to the initial cross-sectional area around the shrunken rods was 6.7+/-1.3 %. The viscosity molecular weight of PLLA reduced from 2 x 10(5) to less than 1 x 10(3). Thus, most of the PLLA had released from the rods. The c-HA/PLLA implants also showed good osteoconductivity, but shrinkage and infiltration of histiocytes were less. No osteolytic or osteoarthritic changes were found.