RESUMEN
BACKGROUND: Intermittent administration of parathyroid hormone (PTH) leads to bone formation by increasing osteoblast numbers and activity levels. Animal studies have shown that intermittent PTH administration increases implant fixation in normal rats. The purpose of this study was to analyze the osseous incorporation of an implant in osteoporotic rats while treating them with intermittent PTH (1-34) or alendronate. METHODS: A total of 36 ovariectomized (OVX) Wistar rats were randomized into three groups. Polymethylmethacrylate cement rods were implanted in one tibia in each rat. The three groups received daily PTH (60 mug/kg body weight [BW]), alendronate (200 mug/kg BW), or saline (0.5 ml/kg BW). A sham-ovariectomized group (n = 12) was treated with saline. After 2 weeks, the area around the implants was analyzed by histomorphometry for bone volume density (BVD) and implant bone contact. Bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry. RESULTS: The BVD was higher in the specimens treated with PTH than in the other groups. PTH improved the BVD, BMD, and implant bone contact. Alendronate doubled the implant bone contact compared to the OVX and sham groups but did not improve BVD or BMD. CONCLUSIONS: These findings confirm that intermittent PTH enhances implant fixation in osteoporotic bone. The clinical significance of these findings is that application of intermittent PTH may be beneficial for early implant fixation in fractures, nonunions, and prosthetic replacements when bone density is decreased.
Asunto(s)
Alendronato/farmacología , Conservadores de la Densidad Ósea/farmacología , Osteogénesis/efectos de los fármacos , Osteoporosis/tratamiento farmacológico , Hormona Paratiroidea/farmacología , Animales , Densidad Ósea/efectos de los fármacos , Femenino , Implantes Experimentales , Osteoporosis/complicaciones , Ovariectomía , Ratas , Ratas WistarRESUMEN
Osteonecrosis of the femoral head is a disease of the young patient which eventually destroys the hip joint. In the early stage of the disease, treatment options are aimed at preserving the femoral head. Unfortunately, many patients present with late-stage disease (Ficat III and IV).In late-stage disease the treatment of choice is total hip arthroplasty. The high failure rate of total hip arthroplasty in young patients with osteonecrosis of the femoral head, however, made it an unfavourable treatment option. The results of hemiresurfacing (femoral resurfacing) in this patient population have been very disappointing due to high revision rates and insufficient pain relief. More recently, promising short- and mid-term results were reported with the use of total resurfacing with a survivorship of 90-93% after 3.4-10 years. Our own results in 60 patients show an overall survivorship of 92% after a mean follow-up of 4.8 years (1.6-6.5 years). Total hip resurfacing is a valuable treatment option for late-stage osteonecrosis based on recent study results.