Journal Publication

Romosozumab lifts spinal bone density in osteogenesis imperfecta but not the hip

A 12-month retrospective study found romosozumab raised spinal bone mineral density in postmenopausal women with classical osteogenesis imperfecta, with weaker effects on hip density and bone microstructure than in osteoporosis patients.

A retrospective analysis found that 12 months of romosozumab increased spinal bone mineral density and osteocalcin in postmenopausal women with classical osteogenesis imperfecta, while hip bone density and peripheral bone microstructure changes were smaller than in women treated for severe osteoporosis.

By AppliedXLJuly 18, 2026

Executive Summary

A retrospective study compared how postmenopausal women with classical osteogenesis imperfecta responded to 12 months of romosozumab against women treated for severe osteoporosis, looking at bone density and bone microstructure at the spine, hip, and tibia.
Romosozumab increased spinal bone mineral density and a marker of bone formation in the osteogenesis imperfecta group, but the drug's effect on hip bone density and on peripheral bone microstructure was smaller than the response seen in the osteoporosis comparison group.
Osteogenesis imperfecta has few pharmacological treatment options, and the divergence between spine and hip response points to a site-specific limit on how far an anti-sclerostin antibody can remodel bone that is intrinsically fragile rather than simply low in density.
The bone-microstructure trends observed at the tibia in the osteogenesis imperfecta group did not reach statistical significance in this small cohort, leaving open whether a larger or longer study would confirm them.

The stake

Osteogenesis imperfecta is described in the study as the most common hereditary bone disorder, marked by bone fragility and impaired bone quality that current pharmacological options do little to address. Anti-sclerostin antibodies such as romosozumab work by blocking sclerostin, a protein that normally restrains bone formation, and are already used to build bone mass in postmenopausal osteoporosis. Whether that same anabolic mechanism translates to a genetic collagen disorder, where the underlying defect is in bone quality rather than simple bone loss, is the question this study set out to address. Romosozumab

How it was done

The analysis retrospectively followed 5 postmenopausal women with classical osteogenesis imperfecta and 10 postmenopausal women with severe osteoporosis, all receiving monthly subcutaneous romosozumab at 210 mg for 12 months. Clinical assessments were taken at baseline, 6 months, and 12 months, with bone mass and structure measured at baseline and at 12 months using dual-energy X-ray absorptiometry for areal bone mineral density and high-resolution peripheral quantitative computed tomography (HR-pQCT) for bone microstructure. Serum and urine markers of bone turnover were measured at each visit. Mean age was 53.6 years in the osteogenesis imperfecta group and 57.2 years in the osteoporosis group, a difference the study reports was not statistically significant. Romosozumab

The result

After 12 months, spinal areal bone mineral density and osteocalcin, a marker of bone formation, increased in the osteogenesis imperfecta group, indicating an anabolic response to treatment. HR-pQCT scans of peripheral bone microstructure showed no statistically significant changes in this group, though the study reports trends and moderate effect sizes suggesting possible improvement. The osteoporosis comparison group showed a more pronounced response overall: greater bone mineral density gains at both the spine and femur, alongside statistically significant improvements in bone microstructure, particularly at the tibia. Romosozumab

The divergence

The spine responded to romosozumab in both groups, but the hip and peripheral skeleton did not track together: osteogenesis imperfecta patients gained spinal density without a matching gain in hip density or measurable microstructure change, while osteoporosis patients gained across all three. That split localizes the drug's anabolic effect in osteogenesis imperfecta largely to the spine, and it distinguishes classical osteogenesis imperfecta bone, built on defective collagen, from postmenopausal osteoporosis bone, which is structurally normal but has lost mass, as a different substrate for the same mechanism to act on. Romosozumab

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