Seeing beyond the surface: bone histomorphometry re-visited-implications for diagnostic pathology

First introduced in the 1950s following the development of the transiliac crest trephine and the advent of plastic embedding techniques, undecalcified bone biopsy revolutionised skeletal pathology by allowing in vivo assessment of mineralised bone. The addition of tetracycline double-labelling in 1969 enabled dynamic measurement of bone formation, and by the 1980s, histomorphometric nomenclature had been standardised, laying the foundation for quantitative diagnosis of metabolic bone disease. Despite these advances, the clinical use of undecalcified biopsy has waned, supplanted by surrogate tools such as dual-energy X-ray absorptiometry and serum markers of turnover. Yet bone biopsy remains the only method that simultaneously captures bone architecture, turnover dynamics, and mineralisation status. While decalcified specimens remain essential for evaluating marrow pathology, neoplasia, and infection, they obliterate the mineral phase, fluorochrome labels, and critical osteoid structures. In contrast, undecalcified, fluorochrome-labelled sections permit precise quantification of bone formation rates, mineralisation lag time, and micro-architectural integrity, offering a direct window into the physiological processes underlying skeletal disease. Histomorphometry has elucidated the pathogenesis of disorders, including osteomalacia, renal osteodystrophy, adynamic bone, and bisphosphonate-induced suppression. It also plays a central role in clarifying turnover status in atypical or treatment-resistant osteoporosis ​and in characterising the altered bone biology of myeloma and metastatic disease, where bone destruction often reflects not only tumour invasion but also uncoupled or arrested regeneration. Beyond standard histology and histomorphometry, microcomputed tomography of biopsy cores enables three-dimensional analysis of trabecular and cortical bone, while emerging techniques, such as Fourier-transform infrared spectroscopy, micro-indentation, and electron microscopy, offer new ways to evaluate bone composition, matrix maturity, and nanoscale organisation. This review re-introduces undecalcified bone biopsy as a vital diagnostic and investigative tool. We outline its methodology, clinical indications, and interpretive value across metabolic and cancer-related bone disorders ​and provide practical guidance for its implementation.