The treatment of osteonecrosis of the femoral head (ONFH) in young and active patients remains a challenge. The purpose of this study was to determine and compare the clinical and radiographic results of the two different hip resurfacing systems; hemi-resurfacing and metal-on-metal total hip resurfacing in patients with ONFH. This study was a retrospective review of 20 patients with 30 hips who had ONFH and underwent hemi-resurfacing or total hip resurfacing between November 2002 and February 2006. We mainly performed hemi-resurfacing for early stage ONFH, and total hip resurfacing for advanced stages. Fifteen hips in 11 patients had a hemi-resurfacing component (Conserve, Wright Medical Co) with a mean age at operation of 50 years and an average follow-up of 5.5 years. Fifteen hips in 10 patients had a metal-on-metal total hip resurfacing component (Birmingham hip resurfacing, Smith & Nephew Co.) with a mean age at operation of 40 years and an average follow-up years.Introduction
Methods
Hip resurfacing has become a popular procedure for young active patients with osteonecrosis of the femoral head. However, it is not yet clear exactly how much osteonecrosis would permit this procedure and how much would be a contraindication. The aim of the present study was to analyze the resurfaced femoral head using finite element models and, in particular, to examine the influence of the extent of osteonecrosis and metaphysical stem shaft angles within the femoral head. We evaluated biomechanical changes at various extents of necrosis and implant alignments, using the finite element analysis method. We established three patterns of necrosis by depth from the surface of femoral head and five stem angles. Extension of necrosis as a quarter of femoral head diameter is type A, from a half is type B, and three-fourths is type C. We set five types of different stem angles from 125 to 145 degrees for the axis of femoral shaft. For these models, we evaluated biomechanical changes associated with the extent of necrosis and the stem alignment.Introduction
Methods
We evaluated the possible induction of a systemic immune response to increase anti-tumour activity by the re-implantation of destructive tumour tissue treated by liquid nitrogen in a murine osteosarcoma (LM8) model. The tumours were randomised to treatment by excision alone or by cryotreatment after excision. Tissue from the tumour was frozen in liquid nitrogen, thawed in distilled water and then re-implanted in the same animal. In addition, some mice received an immunological response modifier of OK-432 after treatment. We measured the levels of interferon-gamma and interleukin-12 cytokines and the cytotoxicity activity of splenocytes against murine LM8 osteosarcoma cells. The number of lung and the size of abdominal metastases were also measured. Re-implantation of tumour tissue after cryotreatment activated immune responses and inhibited metastatic tumour growth. OK-432 synergistically enhanced the anti-tumour effect. Our results suggest that the treatment of malignant bone tumours by reconstruction using autografts containing tumours which have been treated by liquid nitrogen may be of clinical value.
The feasibility of bone transport with bone substitute and the factors which are essential for a successful bone transport are unknown. We studied six groups of 12 Japanese white rabbits. Groups A to D received cylindrical autologous bone segments and groups E and F hydroxyapatite prostheses. The periosteum was preserved in group A so that its segments had a blood supply, cells, proteins and scaffold. Group B had no blood supply. Group C had proteins and scaffold and group D had only scaffold. Group E received hydroxyapatite loaded with recombinant human bone morphogenetic protein-2 and group F had hydroxyapatite alone. Distraction osteogenesis occurred in groups A to C and E which had osteo-conductive transport segments loaded with osteo-inductive proteins. We conclude that scaffold and proteins are essential for successful bone transport, and that bone substitute can be used to regenerate bone.
We carried out limb lengthening in rabbits and then transplanted osteoblast-like cells derived from the tibial periosteum to the centres of distracted callus immediately after distraction had been terminated. Two weeks later the transaxial area ratio at the centre of the distracted callus and the bone mineral density (BMD) were significantly higher in the transplanted group, by 21% and 42%, respectively, than in the non-injected group or the group injected with physiological saline (p <
0.05). Callus BMD as a percentage of density in uninvolved bone was also significantly higher in the transplanted group (p <
0.05) than in the other two groups, by 27% and 20% in the second and fourth weeks, respectively (p <
0.05). Mechanically, the callus in the transplanted group tended to be stronger as shown by the three-point bending test although the difference in fracture strength was not statistically significant. Our results show that transplantation of osteoblast-like cells promotes maturity of the distracted callus as observed at the second and fourth weeks after lengthening. The method appears promising as a means of shortening the consolidation period of callus distraction and decreasing complications during limb lengthening with an external fixator.
