骨形成不全症

Osteogenesis imperfecta (OI) type VIII is an autosomal recessive skeletal dysplasia caused by P3H1 variants, resulting in defective collagen post-translational modification and increased bone fragility. Teriparatide (TPTD), a recombinant parathyroid hormone analogue, stimulates osteoblast activity and bone formation and is approved for the treatment of osteoporosis in adults. A 16-year-old male with genetically confirmed OI type VIII presented with delayed union with characterized by the absence of radiographic evidence of healing six months after femoral osteotomy and intramedullary rodding surgery. His prior management included intermittent bisphosphonate therapy which had improved bone mineral density. He had no recent history of fractures. Off-label therapy with TPTD (20 µg/day subcutaneously) was initiated and continued for six months. Although systemic markers of bone formation showed no remarkable changes, except osteocalcin, during therapy, serial radiographs confirmed successful bone union. The treatment was well tolerated, with no reported side effects; however, mild hypercalcemia with hypercalciuria, which persisted after discontinuation of TPTD therapy, was detected. Bisphosphonate therapy was resumed upon completion of TPTD treatment. This case represents the first documented use of TPTD to promote osteotomy healing in an adolescent with OI. The favourable clinical and radiologic outcome suggests a potential role for anabolic therapy in managing complex bone healing challenges in paediatric OI. Further research is warranted to evaluate safety and efficacy in this population.

Dentinogenesis Imperfecta (DI) is a rare genetic disorder that disrupts the structure and mechanical integrity of dentin, often through alterations to the collagen matrix. In cases associated with Osteogenesis Imperfecta, DI arises from COL1A1 or COL1A2 variants (DI type I). The multiscale mechanisms linking alterations of the collagenic scaffold to dentin microstructural defects remain poorly understood. In this proof-of-concept study, we employed a multimodal 3D characterization framework combining biochemical assays and advanced imaging techniques to investigate the relationship between collagen integrity, mineral organization, and microstructural defects in four (n=4) primary teeth from a DI patient carrying a COL1A2 variant (c.982G>A (p.Gly328Ser)) and eight (n=8) primary teeth from healthy donors. A threefold increase in molecular-level collagen uncoiling (i.e., denaturation) was found in DI dentin compared to healthy dentin using trypsin-hydroxyproline assays. A reduction in the second harmonic generation signal combined with increased spatial variability were observed, indicating pronounced heterogeneities in the collagen scaffold. These heterogeneities were spatially associated with disorganization of the mineral phase, the emergence of hypermineralized regions, and a 30% higher mean mineral density, as measured by high-resolution micro-computed tomography. Severe disruption and partial occlusion of the tubular network were further identified using confocal microscopy, resulting in reduced porosity. These results support a multiscale association between collagen alterations, mineral heterogeneity, and pore network disruption, consistent with a model in which compromised collagen integrity alters the mineral organization and the tubular network of dentin. Although requiring confirmation on larger cohorts, these findings provide a preliminary mechanistic framework for understanding how disruptions of the hierarchical structure of DI dentin, impairing its toughness, may originate from molecular collagen denaturation. Statement of significance: Dentinogenesis Imperfecta (DI) is a rare genetic disorder that weakens teeth, leading to fractures and enamel loss. However, how molecular defects translate into fragile dental tissue remains poorly understood. In this proof-of-concept study, we show that a COL1A2 mutation induces collagen denaturation at the molecular scale, which is associated with major disruptions in dentin structure and mineralization at larger scales. Such structural changes are known to reduce tissue toughness. Our findings provide early but compelling evidence for a direct link between molecular-scale collagen defects and macroscopic fragility in dentin. This work introduces a multiscale framework contributing to the understanding of structure-property relationships in mineralized biological tissues.

UNLABELLED: This study explored whether Romosozumab, an anti-sclerostin antibody, can improve bone quality in women with Osteogenesis imperfecta. After 12 months, spinal areal bone mineral density increased, showing a beneficial treatment effect, although changes in hip bone density and bone structure were less pronounced than in women with severe osteoporosis. PURPOSE: Osteogenesis imperfecta (OI) is the most common hereditary bone disorder, characterized by increased bone fragility and impaired bone quality, but pharmacological treatment is limited. Ongoing clinical trials investigate monoclonal anti-sclerostin antibodies for OI patients, offering new hope for reducing bone fragility by increasing bone mass. METHODS: Postmenopausal women with either OI (n = 5) or severe osteoporosis (OPO, n = 10) receiving Romosozumab monthly (210 mg s.c.) for 12 months were analyzed retrospectively. Clinical assessments were performed at baseline, after 6 months, and after 12 months. Bone mass and structure were evaluated at baseline and after 12 months of treatment. In addition, serum and urine markers of bone turnover were analyzed at each time point. RESULTS: The mean age of the participants was 53.6 ± 8.9 years for OI patients and 57.2 ± 5.8 years for OPO patients (p = 0.444). After 12 months of Romosozumab treatment, spinal aBMD and osteocalcin increased significantly in OI patients, indicating an anabolic response. HR-pQCT analysis revealed no statistically significant microstructural changes in patients with OI, although trends and moderate effect sizes suggested potential improvements. In patients with OPO, we observed a more pronounced response of bone turnover markers with greater aBMD gains at both the spine and femur, as well as significant improvements in bone microstructure, particularly at the tibia. CONCLUSIONS: Romosozumab treatment in postmenopausal women with OI resulted in a significant increase in spinal aBMD, though the effect on hip aBMD and peripheral bone microstructure was limited in contrast to postmenopausal osteoporosis.

Atypical femoral fractures (AFF) are rare fractures with characteristic radiographic features, most commonly associated with long-term bisphosphonate use. Their occurrence in patients with osteogenesis imperfecta (OI), a hereditary bone disease leading to bone fragility, is not well understood. In this study, 138 adults with genetically confirmed classical OI were screened for AFF. Five patients with AFF were identified and compared to an age- and treatment-matched adult OI cohort without AFF (n = 23). Demographical parameters, biochemical markers, bone mineral density (DXA), bone microarchitecture (HR-pQCT), and radiographs were analyzed. In addition, antiresorptive therapy and the duration of treatment were determined and compared. In the screened OI cohort, AFF prevalence was 3.6%. No significant differences were observed between groups regarding age, weight, height, BMI, fracture history, bone mineral density, or antiresorptive therapy exposure and duration. HR-pQCT showed no significant microarchitectural differences, although a trend toward higher cortical thickness was noted in AFF patients. AFF are a rare complication in adults with classical OI and appear to be multifactorial in origin. Our findings suggest that AFF are not exclusively related to antiresorptive therapy but may be influenced by disease-specific factors, particularly the underlying collagen defect, femoral deformities and altered biomechanics. Individualized management strategies are essential, and further studies are needed to clarify underlying mechanisms and best treatment options.

Genetic bone diseases are a rare group of afflictions suffered by the general population. However, their rarity should not diminish research efforts to help patients understand and treat their diseases. This review summarizes the pathology, symptoms, diagnosis, and treatment insight into six well-known genetic bone diseases. Only six bone diseases are included due to the relatively low prevalence of them as whole limiting our scope to ensure accurate information and attention is provided for each disease individually. A literature search of PubMed is conducted, including studies published within the past five years (January 2020-December 2025). Thirty-six studies met inclusion criteria, and no significant risk of bias is identified among the selected articles. Study findings are synthesized into disease overview, clinical and radiographic features, and diagnostic and treatment approaches. Actively developing or novel therapies relevant to each disease are also included. These treatments include: fresolimumab for osteogenesis imperfecta, small interfering ribonucleic acid (RNA) therapy for Osteopetrosis, denosumab for Paget's disease of bone, vosoritide/recifercept/infigratinib for achondroplasia, mesenchymal stem cell therapy for craniosynostosis, and combination losartan and atenolol therapy for Marfan syndrome. These treatments are generally more recently acknowledged in literature and are either actively undergoing research or require further research to determine their efficacy.