Bone

The aim of the present study was to evaluate the effect of hemodialysis and renal failure on serum bone markers. Serum total alkaline phosphatase (TAP), procollagen type I aminoterminal propeptide (PINP), and Β-carboxyterminal telopeptide of type I collagen (Β-CTX), as well as intact parathyroid hormone (iPTH), creatinine, and total protein were measured in 14 patients with endstage renal disease (ESRD) before and at 1, 2, and 4 h during a hemodialysis session, and at the same sampling interval in 6 renal transplant recipients. The results were compared to those obtained in 20 healthy adults. All patients showed increased baseline mean values of PINP, Β-CTX, and iPTH. Β-CTX differed significantly between hemodialysis patients and renal transplant recipients. TAP and Β-CTX were the only markers which correlated with iPTH (P ≪ 0.05) and creatinine values (P ≪ 0.001), respectively. Renal transplant recipients did not show significant variations in the evolution of mean values of bone markers throughout the study, whereas, during the dialysis period, all the bone markers analyzed in the study showed a significant change. The change differed depending on the marker considered: Β-CTX showed a significant decrease at the end of the session, TAP increased at this time and, although PINP showed an initial increase during hemodialysis, no significant changes were observed at the end of the session. We conclude that bone markers are significantly influenced by hemodialysis, especially serum TAP and Β-CTX. ESRD is associated with an increase in these bone markers, in some cases related to iPTH values and in others to glomerular function. These findings should be taken into account when evaluating bone markers in these patients.

IBIDS is a syndrome characterized by ichthyosis, brittle hair, impaired intelligence, decreased fertility, and short stature, but unassociated with skeletal lesions. This condition is considered a form of trichothiodystrophy because hair from several cases has been found to have a low sulfur content. We describe a 9-year and 10-month-old white boy whose clinical features resemble the IBIDS syndrome (ichthyosis, brittle hair, cataracts, and short stature), but who also has marked axial osteosclerosis and peripheral osteopenia. No abnormalities of mineral homeostasis were noted. Histopathologic assessment of nondecalcified bone specimens excluded osteopetrosis, but suggested slow skeletal remodeling. When subjected to polarized light microscopy, his hair exhibited the band-like pattern of birefringence described in trichothiodystrophy. Literature review disclosed 8 patients, 2 of whom had been diagnosed as trichothiodystrophy, with like clinical features including osteosclerosis. These skeletal abnormalities together with clinical features of the IBIDS/trichiodystrophy syndrome, we believe, reflect the prototype of a disorder that seems best described as central osteosclerosis with ectodermal dysplasia.

Vertebral fractures are the classic hallmark of osteoporosis, yet little is known of their epidemiology. The incidence of clinically diagnosed vertebral fractures was therefore directly assessed in the predominantly white (European descent) population of Rochester, Minnesota. Altogether, 341 Rochester residents were radiologically diagnosed for the first time with one or more vertebral fractures in the 5 year study period, 1985–1989. The overall age- and sex-adjusted incidence rate was 117 per 100,000 person-years (95% CI, 105 to 130). The age-adjusted rate in women (145 per 100,000 person-years) was almost twice that in men (73 per 100,000 person-years). Of all fractures, 47 (14%) followed severe trauma, 282 (83%) followed moderate or no trauma, and 12 (3%) were pathologic. Incidence rates for fractures following moderate trauma were higher in women than in men and rose steeply with age in both genders. In contrast, fractures following severe trauma were more frequent in men, and their incidence increased less with age. These Rochester rates are greater than those previously reported from studies in Britain and Sweden but lower than the incidence rates extrapolated from a prevalence study in this population.

Although the precise mechanisms of the conversion of predentin to dentin are not well understood, several lines of evidence implicate the noncollagenous proteins (NCPs) as important regulators of dentin biomineralization. Here we compared the in vivo temporospatial expression patterns of two dentin NCP genes, dentin matrix protein 1 (Dmp1), and dentin sialophosphoprotein (DSPP) in developing molars. Reverse transcription-polymerase chain reaction was performed on embryonic day 13 to 1-day-old first molars using Dmp1- and DSPP-specific primer sets. Dmp1 transcripts appeared at the late bud stage, while DSPP mRNA was seen at the cap stage. Expression of both genes was sustained throughout odontogenesis. In situ hybridization analysis revealed interesting differences in the expression patterns of these genes. While Dmp1 and DSPP showed coexpression in young odontoblasts before the start of mineralization, the expression of these genes was notably distinct at later stages. Dmp1 expression decreased in secretory odontoblasts after the appearance of mineral, while high levels of DSPP were sustained in odontoblasts. In early secretory ameloblasts, DSPP expression was transient and down-regulated with the appearance of dentin matrix. Interestingly, Dmp1 expression became evident in ameloblasts during the maturative phase of amelogenesis. In contrast to Dspp expression that was tooth-specific, Dmp1 was expressed by osteoblasts throughout ossification in the skeleton. Probes directed to the “DSP” and “DPP” regions of the DSPP gene showed identical patterns of mRNA expression. These data show that the developmental expression patterns of Dmp1 and DSPP are distinct, implying that these molecules serve different biological functions in vivo.

Raloxifene (RAL) and alendronate (ALN) improve the biomechanical properties of bone by different mechanisms. The goal here was to investigate the effects of combination treatment of RAL and ALN on the biomechanical properties of vertebral bone. Six-month-old Sprague-Dawley rats (n = 80) were randomized into five experimental groups (sham, OVX, OVX + RAL, OVX + ALN, and OVX + RAL + ALN; n = 16/group). Following euthanization, structural and derived material biomechanical properties of vertebral bodies were assessed. Density and dynamic histomorphometric measurements were made on cancellous bone. The results demonstrate that the structural biomechanical properties of vertebral bone are improved with the combination treatment. Stiffness and ultimate load of the OVX + RAL and OVX + ALN groups were significantly lower than those of sham animals, but the combination treatment with RAL + ALN was not significantly different from sham. Furthermore, the OVX + RAL + ALN group was the only agent-treated group in which the ultimate load was significantly higher than that in OVX animals (p < .05). Cancellous bone fractional volume (BV/TVcanc) and bone mineral density (aBMD) also were improved with the combination treatment. BV/TVcanc of the OVX + RAL + ALN group was 6.7% and 8.7% greater than that of the OVX + RAL (p < .05) and OVX + ALN (p < .05) groups, respectively. Areal BMD of the OVX + RAL or OVX + ALN groups was not significantly different from that in OVX animals, but the value in animals undergoing combination treatment was significantly higher than that in OVX or OVX + RAL animals alone and not significantly different from that in sham-operated animals. Turnover rates of both the RAL + ALN and ALN alone groups were lower than in the RAL-treated alone group (p < .05). We conclude that the combination treatment of raloxifene and alendronate has beneficial effects on bone volume, resulting in improvement in the structural properties of vertebral bone. © 2011 American Society for Bone and Mineral Research.

Mechanical loading has been shown to modulate longitudinal bone growth and cellular activity of the growth plate. Nevertheless, limited and controversial results exist regarding the effect of exercise on a physiological level on the growth plate. The present study investigated whether dose-dependent voluntary exercise has an influence on morphological, biochemical, and mechanical factors of the distal femoral growth plate of

The use of, and interest in, total knee replacements (TKR) has been growing over the last few
decades. Loosening and migration of tibial components have been identified as one of the
primary causes of failure in the proximal tibia. Clinical studies show the use of metal
implants as one of the primary methods for the treatment of knee joints and associated bone
defects. Alignment and fixation techniques play an important role in achieving high success
rates. Defective bone stock requires the use of augments to stabilise the tibial plate. In these
cases, current clinical practice is to use an extended implant stem to ensure stability. The
problem with this is that it reduces the potential for future knee revision
In this research Finite Element Analysis (FEA) has been used to undertake virtual in-vivo
assessment of various configurations of augmented and non-augmented TKR that can be used
for the treatment of tibial defects. These configurations are based on a standard tibial insert,
namely a fixed bearing revision tibial tray. This has provided insight and information that can
be used to improve surgical decision making when dealing with defective bone stock.
The 3D FE models of a non-defect TKR with a fixed bearing tibial insert showed a stable
construct with stresses lying within an allowable threshold. The use of a stem extension
generally showed a reduction in stress levels in the cancellous bone contributing to an
increase in stress shielding and thus it is recommended that these are not used unless there is
some other overriding clinical requirement.
Further, the analysis demonstrated that, contrary to some clinical opinion, wedge
augmentation (rather than block augmentation) may provide a better approach to treat the
defect. This was largely due to improved cement stress distribution caused by a mechanism
termed “reverse-shear”.
The use of a cement augment was found to provide a more favourable stress distribution in
the cancellous bone. However, metal augments have been recommended as the cement
augment was shown to operate too close to its fatigue endurance limits.

Vertebral fractures are the classic hallmark of osteoporosis, yet little is known of their epidemiology. The incidence of clinically diagnosed vertebral fractures was therefore directly assessed in the predominantly white (European descent) population of Rochester, Minnesota. Altogether, 341 Rochester residents were radiologically diagnosed for the first time with one or more vertebral fractures in the 5 year study period, 1985–1989. The overall age- and sex-adjusted incidence rate was 117 per 100,000 person-years (95% CI, 105 to 130). The age-adjusted rate in women (145 per 100,000 person-years) was almost twice that in men (73 per 100,000 person-years). Of all fractures, 47 (14%) followed severe trauma, 282 (83%) followed moderate or no trauma, and 12 (3%) were pathologic. Incidence rates for fractures following moderate trauma were higher in women than in men and rose steeply with age in both genders. In contrast, fractures following severe trauma were more frequent in men, and their incidence increased less with age. These Rochester rates are greater than those previously reported from studies in Britain and Sweden but lower than the incidence rates extrapolated from a prevalence study in this population.

The anatomy of the New Zealand tuatara has been examined extensively by anatomists and palaeontologists because it represents the only living member of the Rhynchocephalia, a group of reptiles that were successful during the time of the dinosaurs. The tuatara is also of interest because of its specialized teeth and a forward chewing stroke that it uses to rip food apart. However, despite several detailed descriptions of the skull, there has been little work on how the individual bones of the skull fit together. Here we provide the first joint by joint ...