Toru Okano

Effect of parathyroid hormone on cortical bone response to in vivo external loading of the rat tibia.

Abstract Cortical bone responses following administration of parathyroid hormone (PTH) were evaluated using a four-point bending device to clarify the relationship between the effect of PTH and mechanical loading. Female Wistar rats, 36-months-old, were used. Rats were randomized into three groups (n = 10/group), namely PTH-5 (5 μg PTH/kg body weight), PTH-30 (30 μg PTH/kg body weight), and PTH-v (vehicle). PTH (human PTH (1–34)) was injected subcutaneously three times/week for 3 weeks. Loads on the right tibia were applied in vivo at 29.1 ± 0.3 N for 36 cycles at 2 Hz 3 days/week for 3 weeks using four-point bending. The administration of PTH and tibial mechanical loading were performed on the same day. After calcein double labeling, rats were killed and tibial cross-sections were prepared from the region with maximal bending at the central diaphysis. Histomorphometry was performed over the entire periosteal and endocortical surfaces of the tibiae, dividing the periosteum into lateral and medial surfaces. The in vivo average peak tibial strains (predicted) on the lateral periosteal surface were 1392.4, 1421.8 and 1384.7 μstrain in PTH-v, PTH-5 and PTH-30 groups, respectively, showing no significant difference among the three groups. Significant loading-related increases in the bone formation surface, mineral apposition rate, and bone formation rate were observed at the periosteal and endocortical surfaces. Significant differences between PTH groups were also seen. Interaction between mechanical loading and PTH was significant at both periosteal and endocortical surfaces. It is concluded that PTH has a synergistic effect on the cortical bone response to mechanical loading.

Effect of ED-71 on modeling of bone in distraction osteogenesis

We investigated the effect of 2-beta-(3-hydroxypropoxy)-1alpha,25-dihydroxyvitamin D3 (ED-71) on the modeling of bone in distraction osteogenesis. The tibiae of 30 rabbits were lengthened by 10 mm in 10 days. Following osteotomy, ED-71 (0.05 microg/kg) was administered subcutaneously twice a week to the ED-71 group until necropsy. The bone mineral content (BMC) of the lengthened callus was measured by dual-energy X-ray absorptiometry (DXA). Five rabbits per group were killed at 1, 3, and 8 weeks after completion of lengthening, and the lengthened callus was examined histologically and histomorphometrically. Bone volume of the lengthened callus was measured by peripheral quantitative computed tomography (pQCT) at 8 weeks after the completion of lengthening. At all timepoints the BMC in the ED-71 group was significantly higher than that in the untreated group. The mineral apposition rate and bone formation rate were higher in the ED-71 group than in the untreated group at 1 and 3 weeks after the completion of lengthening on the coronal section. In cross sections, the cortical area and width in the ED-71 group showed significantly higher values than in the untreated group at 8 weeks after the completion of lengthening. Both the endosteal osteoid surface and endosteal eroded surface showed no differences between groups. However, the endosteal mineral apposition rate and endosteal bone formation rate were significantly higher in the ED-71 group. At 8 weeks after completion of lengthening, the intracortical area and intracortical BMC were significantly greater in the ED-71 group than in the untreated group, but no significant difference was noted in intracortical BMD. These findings indicate that ED-71 increases callus volume during the early period after the completion of lengthening, resulting in thick cortical bone formation.

Effects of ovariectomy and estrogen replacement therapy on arthritis and bone mineral density in rats with collagen-induced arthritis

We investigated the effects of ovariectomy (ovx) and estrogen replacement therapy (ERT) on bone mineral density (BMD) and arthritis severity in rats with collagen-induced arthritis (CIA). Seven-month-old female Sprague-Dawley rats were separated into a sham group (n = 8), CIA group (n = 14), ovx group (n = 10), CIA + ovx group (n = 11), and CIA + ovx + ERT group (n = 14). In these groups, ovx was performed at 7 days, and ERT (17beta-estradiol at 20 microg/kg three times per week) was initiated 8 days after sensitization. Every 2 weeks, until 8 weeks after sensitization, arthritis score and hind paw thickness were evaluated, and BMD of the trabecular and cortical bones in the metaphysis and diaphysis of the tibia were measured by peripheral quantitative computed tomography. The arthritis score was highest in the CIA + ovx group at all timepoints after sensitization. The hind paw thickness was significantly higher in the CIA + ovx group than in the CIA group at 8 weeks after sensitization (p < 0.05). Both the arthritis score and hind paw thickness were lower in the CIA + ovx + ERT group than in the CIA + ovx group. BMD in the metaphysis was significantly decreased in both the trabecular and cortical bones in the CIA + ovx group compared with those in the CIA group at 4, 6, and 8 weeks after sensitization. In the CIA + ovx group, trabecular BMD was changed by -34 +/- 11%, and cortical BMD changed by -14 +/- 7% in the metaphysis at 8 weeks compared with those at 0 week. In the CIA group, changes of BMD in the metaphysis were -7 +/- 11% in trabecular bone and 0 +/- 7% in cortical bone. These differences of trabecular and cortical bone loss in the metaphysis were significant (both p < 0.01). BMD reduction was significantly less in the CIA + ovx + ERT group than in the CIA + ovx group at 6 and 8 weeks after sensitization. Although BMD in the diaphysis was also reduced in the groups with CIA, the degree of reduction was smaller than in the metaphysis. We conclude that ovx in CIA rats could enhance the severity of arthritis and bone loss, and that ERT could suppress arthritis and bone loss.

Insufficiency fracture of the femoral head in patients with severe osteoporosis-report of 2 cases

(1999). Insufficiency fracture of the femoral head in patients with severe osteoporosis-report of 2 cases. Acta Orthopaedica Scandinavica: Vol. 70, No. 1, pp. 87-89.

Measurement of human trabecular bone by novel ultrasonic bone densitometry based on fast and slow waves

SummaryTwo longitudinal transmitted waves, fast and slow waves, were observed by employing a new quantitative ultrasound (QUS) method. The trabecular bone measurements generated by this method reflect three-dimensional structural information, and the new QUS parameters were able to identify vertebral fractures.IntroductionThe aims were to identify new quantitative ultrasound (QUS) parameters that based on new QUS method reflecting not only bone volume but also the microstructures of trabecular bone ex vivo and to observe how much they predict fracture risk in vivo.MethodsEx vivo measurement: Three human femoral heads were used for the experiment. Attenuation of the slow wave, attenuation of the fast wave, speed of the slow wave, speed of the fast wave (SOFW), bone mass density of trabecular bone, and elastic modulus of the trabecular bone (EMTb) of each specimen were obtained using a new QUS method and compared with three-dimensional structural parameters measured by micro-computed tomography. In vivo measurement: Eighty-nine volunteers were enrolled, and the bone status in the distal radius was measured using a new QUS method. These parameters were compared with data evaluated by peripheral quantitative computed tomography and dual X-ray absorptiometry.ResultsEx vivo measurement: SOFW and EMTb showed correlations with the parameter of trabecular anisotropy. In vivo measurement: The new QUS parameters were able to identify vertebral fractures.ConclusionThe newly developed QUS technique reflects the three-dimensional structure and is a promising method to evaluate fracture risk.

Bone Mass Changes of Tibial and Vertebral Bones in Young and Adult Rats With Collagen-induced Arthritis

To study the effect of arthritis on bone mass, bone mineral density (BMD) of cancellous and cortical bone in the tibial metaphysis and diaphysis in 2- and 7-month-old rats with collagen-induced arthritis (CIA) was serially measured using peripheral quantitative computed tomography (pQCT). BMD in the fourth lumbar vertebra in 7-month-old CIA rats was also measured by pQCT. The fourth lumbar vertebral body, distal femur, and proximal tibia in 7-month-old CIA rats were analyzed histomorphometrically. Changes in BMD differed between 2-month-old (young) and 7-month-old (adult) CIA rats. Although the BMD for the proximal tibia (2 mm and 5 mm distal from the growth cartilage) in young CIA rats decreased compared with that in control rats, the values exceeded the initial value during the arthritis course. On the other hand, bone loss in adult CIA rats occurred predominantly in the cancellous bone of the periarticular region of the tibia (2 mm distal from the growth cartilage), in which the enhancement of bone resorption and reduced bone formation were observed histomorphometrically. No remarkable changes were demonstrated in BMD or histomorphometrical analysis for the lumbar vertebra during the experimental course. These results suggest that bone loss in adult CIA rats resembles the osteoporosis that develops during the early stage of human rheumatoid arthritis. We conclude that adult CIA rats are more appropriate than young CIA rats as an experimental model of secondary osteoporosis due to rheumatoid arthritis.

Longitudinal change in periprosthetic, peripheral, and axial bone mineral density after total hip arthroplasty

Abstract To determine the bone mineral changes after total hip arthroplasty, bone mineral densities (BMD) at the periprosthetic interface, lumbar spine, radius, and calcaneus were measured in a prospective and longitudinal observation. Twenty-four patients (24 joints) who had received a total hip arthroplasty and were followed longitudinally were enrolled in this study. The subjects comprised 2 men and 22 women with a mean age of 69.2 years at the time of surgery. Bone mineral measurements were performed at 1, 3, 6, 12, 18, 24, 30, and 36 months after surgery. The periprosthetic BMD after total hip arthroplasty continued to decrease for 6–12 months after surgery, and then recovered, except in Gruen zone 7 (the calcar region). The calcaneal BMD decreased rapidly for 3 months after surgery before increasing. The lumbar BMD showed a decreasing trend for 12 months after surgery, and then increased gradually. The radial BMD was not affected by surgery. We conclude that changes in the periprosthetic BMD after total hip arthroplasty show an apparent difference between zones, and also differ between the weight-bearing bones and the nonweight-bearing bones.

Study on Skeletal Tuberculosis in Past 20 Years

We investigated 24 patients with skeletal tuberculosis in the past 20 years. The age range was from 24 to 86 years (average: 57.2 years). Half of the patients (12 cases) were tuberculous spondylitis. Of nine cases excluding the tuberculous spondylitis cases, three were tenosynovitis and two were psoitis. There was no tuberculous arthritis of the hip and knee joint. Tuberculin reaction was considered to be useful for screening inspection in the diagnosis of skeletal tuberculosis because it was positive in 70% of these patients. If swelling without heat or redness that does not react to antibiotics is seen, tuberculosis should be suspected.

Overlooked Patients with Congenital Dislocation of the Hip from Mass Screening

Between 1974 and 2002, eleven patients (1 male and 10 females) received a delayed diagnosis of congenital dislocation of the hip (CDH) 7 to 44 months (the average age 17 months) after birth. Four patients had not walked yet, and 7 patients had started walking at an average of 13.7 months after birth. Difficulty in walking was noticed in 7 patients. There were not limitations of hip joint abduction or asymmetry of thigh folds in half of the patients. It was concluded that other methods such as ultrasound screening were necessary to prevent overlooking CDH, since some patients with CDH were lacking of typical clinical signs.