Evaluation of osteoporosis using skin thickness measurements

In Vivo Assessment of Skin Surface Pattern: Exploring Its Potential as an Indicator of Bone Biomechanical Properties

The mechanical properties of bone tissue are the result of a complex process involving collagen-crystal interactions. The mineral density of the bone tissue is correlated with bone strength, whereas the characteristics of collagen are often associated with the ductility and toughness of the bone. From a clinical perspective, bone mineral density alone does not satisfactorily explain skeletal fragility. However, reliable in vivo markers of collagen quality that can be easily used in clinical practice are not available. Hence, the objective of the present study is to examine the relationship between skin surface morphology and changes in the mechanical properties of the bone. An experimental study was conducted on healthy children (n = 11), children with osteogenesis imperfecta (n = 13), and women over 60 years of age (n = 22). For each patient, the skin characteristic length (SCL) of the forearm skin surface was measured. The SCL quantifies the geometric patterns formed by wrinkles on the skin's surface, both in terms of size and elongation. The greater the SCL, the more deficient was the organic collagen matrix. In addition, the bone volume fraction and mechanical properties of the explanted femoral head were determined for the elderly female group. The mean SCL values of the healthy children group were significantly lower than those of the elderly women and osteogenesis imperfecta groups. For the aged women group, no significant differences were indicated in the elastic mechanical parameters, whereas bone toughness and ductility decreased significantly as the SCL increased. In conclusion, in bone collagen pathology or bone aging, the SCL is significantly impaired. This in vivo skin surface parameter can be a non-invasive tool to improve the estimation of bone matrix quality and to identify subjects at high risk of bone fracture.

Dermal ultrasound measurements for bone quality assessment : An investigation of advanced glycation endproducts derived from confocal fluorescence microscopy

Bone quality is increasingly being recognized in the assessment of fracture risk. Nonenzymatic collagen cross-linking with the accumulation of advanced glycation end products stiffens and embrittles collagen fibers thus increasing bone fragility. Echogenicity is an ultrasound (US) parameter that provides information regarding the skin collagen structure. We hypothesized that both skin and bone collagen degrade in parallel fashion. Prospectively collected data of 110 patients undergoing posterior lumbar fusion was analyzed. Preoperative skin US measurements were performed in the lumbar region to assess dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation endproducts (fAGEs). Pearson's correlation was calculated to examine relationships between  (1) US and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), diabetes mellitus, and hemoglobin A1c (HbA1c) was used to investigate associations between US and fAGEs. One hundred and ten patients (51.9% female, 61.6 years, BMI 29.8 kg/m2 ) were included in the analysis. In the univariate analysis cortical and trabecular fAGEs decreased with age, but only in women (cortical: r = -0.32, p = 0.031; trabecular: r = -0.32; p = 0.031). After adjusting for age, sex, BMI, diabetes mellitus, and HbA1c, lower dermal (β = 1.01; p = 0.012) and subcutaneous (β = 1.01; p = 0.021) echogenicity increased with increasing cortical fAGEs and lower dermal echogenicity increased with increasing trabecular fAGEs (β = 1.01; p = 0.021). This is the first study demonstrating significant associations between skin US measurements and in vivo bone quality parameters in lumbar fusion patients. As a noninvasive assessment tool, skin US measurements might be incorporated into future practice to investigate bone quality in spine surgery patients.

Skin Ultrasound Measurement as a Potential Marker of Bone Quality: A Prospective Pilot Study of Patients undergoing Lumbar Spinal Fusion

Bone mineral density (BMD) is not the sole predictor of fracture development. Qualitative markers including bone collagen maturity contribute to bone fragility. Bone and related type I collagen containing connective tissues degenerate in parallel fashion. With aging, changes in skin collagen content and quality have been observed that can be detected on ultrasound (US) as a decrease in dermal thickness and an increase in reticular layer echogenicity. We hypothesized that US dermal thickness and echogenicity correlate with bone collagen maturity. Data of 43 prospectively enrolled patients (mean age 61 years, 24 females), who underwent instrumented, posterior lumbar fusion was analyzed. Besides preoperative quantitative computed tomography (QCT) and skin US measurements, intraoperative bone biopsies were obtained and analyzed with Fourier-transform infrared spectroscopy. Among men, there was no correlation between US measurements and collagen maturity. Among women, dermal layer thickness correlated negatively with collagen maturity in trabecular bone of the iliac crest (r = -0.51, p = 0.01) and vertebra (r = -0.59, p = 0.01) as well as in cortical bone of the iliac crest (r = -0.50, p = 0.02) and vertebra (r = -0.50, p = 0.04). In addition, echogenicity correlated positively with collagen maturity in trabecular vertebral bone (r = 0.59, p = 0.01). In both genders, US measurements showed no correlation with QCT BMD. In summary, ultrasound skin parameters are associated with bone quality factors such as collagen maturity, rather than bone quantity (BMD). Ultrasound of the skin may thereby be an easy and accessible take off point for diagnosis of bone collagen maturity and connective tissue degeneration in the future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2508-2515, 2019.

Correlation between skin and bone parameters in women with postmenopausal osteoporosis: A systematic review

Skin and bone share similarities in terms of biochemical composition.Some authors have hypothesized that their properties could evolve concomitantly with age, allowing the estimation of the parameters of one from those of the other.We performed a systematic review of studies reporting the correlation between skin and bone parameters in women with postmenopausal osteoporosis.Fourteen studies - including 1974 patients - were included in the review.Three of these studies included two groups of participants - osteoporotic and non-osteoporotic - in order to compare skin parameters between them: two studies found a significant difference between the two groups and one did not.Eleven of these studies included one population of interest and compared its skin and bone parameters in a continuous manner: eight studies compared dermal thickness to bone mineral density (seven found a significant correlation [R = 0.19-0.486] and one did not); two studies compared skin elasticity to bone mineral density (both found a significant correlation [R = 0.44-0.57); and one study compared skin collagen to bone mineral density and found a significant correlation (R = 0.587).It can be assumed that the estimation of skin alterations from ageing could help in estimating concomitant bone alterations. Cite this article: EFORT Open Rev 2018;3:449-460. DOI: 10.1302/2058-5241.3.160088.

Developing novel prognostic biomarkers for multivariate fracture risk prediction algorithms

Multivariate prediction algorithms such as FRAX® and QFractureScores provide an opportunity for new prognostic biomarkers to be developed and incorporated, potentially leading to better fracture prediction. As more research is conducted into these novel biomarkers, a number of factors need to be considered for their successful development for inclusion in these algorithms. In this review, we describe two well-known multivariate prediction algorithms for osteoporosis fracture risk applicable to the UK population, FRAX and QFractureScores, and comment on the current prognostic tools available for fracture risk; dual X-ray assessment, quantitative ultrasonography, and genomic/biochemical markers. We also highlight the factors that need to be considered in the development of new biomarkers. These factors include the requirement for prospective data, collected in new cohort studies or using archived samples; the need for adequate stability data to be provided; and the need for appropriate storage methods to be used when retrospective data are required. Area under the receiver operating characteristic curve measures have been found to have limited utility in assessing the impact of the addition of new risk factors on the predictive performance of multivariate algorithms. New performance evaluation measures, such as net reclassification index and integrated discrimination improvement, are increasingly important in the evaluation of the impact of the addition of new markers to multivariate algorithms, and these are also discussed.

Associação entre espessura da pele e densidade óssea em mulheres adultas

FUNDAMENTOS: Osteoporose acomete principalmente mulheres em menopausa e idosos, predispondo a fraturas que geram morbidade, mortalidade e custos ao sistema de saúde. Como o colágeno dérmico diminui paralelamente à redução da massa óssea com o envelhecimento, a medida da espessura da pele pode ser indício do risco de osteoporose. OBJETIVOS: Avaliar a correlação entre densidade óssea e espessura da pele do dorso das mãos de mulheres adultas. MÉTODOS: Estudo transversal envolvendo mulheres adultas atendidas em ambulatório de hospital universitário submetidas à densitometria óssea, que foram avaliadas individualmente e mensurada, por paquímetro, a espessura da pele no dorso das mãos, além de investigados demais fatores de risco para osteoporose. RESULTADOS: Avaliaram-se 140 pacientes. A média (±dp) de idade foi de 57 (±11) anos; a média da espessura da pele do dorso das mãos foi de 1,4 (±0,4) mm. Houve correlação entre as medidas das mãos direita e esquerda (R=0,9; p<0,01). Observou-se correlação direta entre as espessuras de pele do dorso das mãos e as densidades ósseas lombares e femorais (p<0,01). Tais resultados permaneceram consistentes mesmo quando ajustados pelas covariáveis: idade, fototipo, índice de massa corpórea, tabagismo, uso de corticoide oral, uso de anti-inflamatório oral e tempo de menopausa. Osteoporose se associou inversamente com a espessura da pele das mãos (Odds Ratio=0,10; p<0,03). CONCLUSÃO: Espessura da pele correlacionou-se, independentemente, com a densidade óssea, sugerindo simultaneidade dos eventos. Sinais cutâneos podem contribuir para a estratificação de risco não invasiva desses pacientes, e colaborar na identificação e tratamentos precoces