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Mustafa Unal

Harvard Medical School, Beth Israel Deaconess Medical Center, Orthopaedics Department, Post-Doc

Case Western Reserve University, Mechanical and Aerospace Engineering, Post-Doc

Vanderbilt University Medical Center, Orthopaedics, Post-Doc

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My current research focuses on translating Raman spectroscopy to the clinic to better understand the changes associated with orthopaedic diseases, and to provide clinically meaningful measurements.

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University of Belgrade

Dominic Thewlis

University of South Australia

Johns Hopkins University

Morad Karimpour

University of Tehran

Bulgarian Academy of Sciences

University of Otago

Enrico Dall'Ara

The University of Sheffield

Indian Institute of Science

Università degli Studi "La Sapienza" di Roma

Nahrul Khair Alang Md Rashid

Universiti Teknologi Malaysia - UTM

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Papers by Mustafa Unal

Collagen bound water is a strong correlate of bone's toughness

Compositional assessment of bone by Raman spectroscopy

The Analyst, 2021

Raman spectroscopy (RS) is used to analyze the physiochemical properties of bone because it is no... more

Constitutive activation of MEK1 in osteoprogenitors increases strength of bone despite impairing mineralization

Bone, 2019

Recent clinical studies have revealed that a somatic mutation in MAP2K1, causing constitutive act... more Recent clinical studies have revealed that a somatic mutation in MAP2K1, causing constitutive activation of MEK1 in osteogenic cells, occurs in melorheostotic bone disease in humans. We have generated a mouse model which expresses an activated form of MEK1 (MEK1DD) specifically in osteoprogenitors postnatally. The skeletal phenotype of these mice recapitulates many features of melorheostosis observed in humans, including extra-cortical bone formation, abundant osteoid formation, decreased mineral density, and increased porosity. Paradoxically, in both humans and mice, MEK1 activation in osteoprogenitors results in bone that is not structurally compromised, but is hardened and stronger, which would not be predicted based on tissue and matrix properties. Thus, a specific activating mutation in MEK1, expressed only by osteoprogenitors postnatally, can have a significant impact on bone strength through complex alterations in whole bone geometry, bone micro-structure, and bone matrix.

Low bone toughness in the TallyHO model of juvenile type 2 diabetes does not worsen with age

Bone, May 1, 2018

Fracture risk increases as type 2 diabetes (T2D) progresses. With the rising incidence of T2D, in... more Fracture risk increases as type 2 diabetes (T2D) progresses. With the rising incidence of T2D, in particular early-onset T2D, a representative pre-clinical model is needed to study mechanisms for treating or preventing diabetic bone disease. Towards that goal, we hypothesized that fracture resistance of bone from diabetic TallyHO mice decreases as the duration of diabetes increases. Femurs and lumbar vertebrae were harvested from male, TallyHO mice and male, non-diabetic SWR/J mice at 16weeks (n≥12 per strain) and 34weeks (n≥13 per strain) of age. As is characteristic of this model of juvenile T2D, the TallyHO mice were obese and hyperglycemic at an early age (5weeks and 10weeks of age, respectively). The femur mid-shaft of TallyHO mice had higher tissue mineral density and larger cortical area, as determined by micro-computed tomography, compared to the femur mid-shaft of SWR/J mice, irrespective of age. As such, the diabetic rodent bone was structurally stronger than the non-diabe...

The Role of Matrix Composition in the Mechanical Behavior of Bone

Current osteoporosis reports, Jan 3, 2018

While thinning of the cortices or trabeculae weakens bone, age-related changes in matrix composit... more While thinning of the cortices or trabeculae weakens bone, age-related changes in matrix composition also lower fracture resistance. This review summarizes how the organic matrix, mineral phase, and water compartments influence the mechanical behavior of bone, thereby identifying characteristics important to fracture risk. In the synthesis of the organic matrix, tropocollagen experiences various post-translational modifications that facilitate a highly organized fibril of collagen I with a preferred orientation giving bone extensibility and several toughening mechanisms. Being a ceramic, mineral is brittle but increases the strength of bone as its content within the organic matrix increases. With time, hydroxyapatite-like crystals experience carbonate substitutions, the consequence of which remains to be understood. Water participates in hydrogen bonding with organic matrix and in electrostatic attractions with mineral phase, thereby providing stability to collagen-mineral interface...

Chemical characterization of Maltese-cross birefringent particles in synovial fluid samples collected from symptomatic joints

Joint, bone, spine : revue du rhumatisme, Jan 28, 2017

Interrelationships between electrical, mechanical and hydration properties of cortical bone

Journal of the Mechanical Behavior of Biomedical Materials, 2018

Interrelationship between electrical and mechanical properties of cortical bone and the role of b... more Interrelationship between electrical and mechanical properties of cortical bone and the role of bone composition in this interrelationship are not comprehensively investigated to date. This study aimed to investigate associations of electrical properties (i.e., specific impedance, dielectric constant, and conductivity) with mechanical properties (i.e., toughness, strength and elastic modulus) of wet and sequentially dehydrated cortical bone. Bovine cortical bone samples (N = 24) were subjected to three-point bending test. A sequential heat treatment protocol ensued to tease out contributions of unbound water and bound water. Demineralization was performed to understand contributions of organic matrix and the mineral phase to the electrical properties of cortical bone. Raman-spectroscopy based water measurement was used to investigate involvement of collagen-and mineralbound water in the electrical properties. Our results showed statistically significant correlations between electrical and mechanical properties of cortical bone. Toughness and ultimate strength were negatively correlated with impedance and positively correlated with conductivity and dielectric constant. The highest correlations between electrical and mechanical properties of cortical bone were typically found at the frequencies of 0.2, 0.5 and 1 MHz. The electrical properties of bone changed significantly as a result of sequential dehydration, indicating that unbound and bound water compartments are the key determinants of the electrical properties. Comparison of porosity matched bone samples with high and low amount of bound water showed that bound water compartments may have an independent role in determining electrical properties of cortical bone. Furthermore, the results indicated that collagen and mineral-bound water may contribute differentially to the electrical properties of a bone. In the overall, our results suggest that electrical properties of cortical bone may be used to assess bone toughness and strength, and also underline the necessity for developing techniques to measure these electrical properties in vivo.

Repetitive short-span application of extracellular calcium is osteopromotive to osteoprogenitor cells

Journal of tissue engineering and regenerative medicine, Jan 17, 2017

Extracellular calcium ([Ca(2+) ]E ) concentration has been suggested to stimulate osteoblastic ac... more Extracellular calcium ([Ca(2+) ]E ) concentration has been suggested to stimulate osteoblastic activity; thus, calcium can be used to enhance fracture healing. However, systemic administration of calcium at high dose levels may cause physiological problems such as hypercalcemia. Short span application of single or repetitive [Ca(2+) ]E stimulus may be suggested as a novel regimen to reduce such side effects. However, osteopromotive effect of such short term [Ca(2+) ]E stimulus on osteoprogenitor cells has not yet been evaluated yet. This study investigated the effects of [Ca(2+) ]E dose (6 mM and 18 mM) and regimen (single, repetitive and continuous) on viability, proliferation, osteogenic gene expression and mineral formation by osteoprogenitor cells. BMP-2 treatment was set as the positive control group. It was observed that repetitive and continuous calcium stimulation resulted in significant enhancement of osteoblastic activity. 6 mM [Ca(2+) ]E significantly increased cell viabi...

Raman spectral markers of collagen denaturation and hydration in human cortical bone tissue are affected by radiation sterilization and high cycle fatigue damage

Journal of the mechanical behavior of biomedical materials, Nov 13, 2017

Thermal denaturation and monotonic mechanical damage alter the organic and water-related compartm... more Thermal denaturation and monotonic mechanical damage alter the organic and water-related compartments of cortical bone. These changes can be detected using Raman spectroscopy. However, less is known regarding Raman sensitivity to detect the effects of cyclic fatigue damage and allograft sterilization doses of gamma radiation. To determine if Raman spectroscopic biomarkers of collagen denaturation and hydration are sensitive to the effects of (a) high cycle fatigue damage and (b) 25kGy irradiation. Unirradiated and gamma-radiation sterilized human cortical bone specimens previously tested in vitro under high-cycle (> 100,000 cycles) fatigue conditions at 15MPa, 25MPa, 35MPa, 45MPa, and 55MPa cyclic stress levels were studied. Cortical bone Raman spectral profiles from wavenumber ranges of 800-1750cm(-1) and 2700-3800cm(-1) were obtained and compared from: a) non-fatigue vs fatigue fracture sites and b) radiated vs. unirradiated states. Raman biomarker ratios 1670/1640 and 3220/294...

Novel Raman Spectroscopic Biomarkers Indicate That Postyield Damage Denatures Bone's Collagen

Journal of Bone and Mineral Research, 2016

Raman spectroscopy has become a powerful tool in the assessment of bone quality. However, the use... more Raman spectroscopy has become a powerful tool in the assessment of bone quality. However, the use of Raman spectroscopy to assess collagen quality in bone is less established than mineral quality. Because postyield mechanical properties of bone are mostly determined by collagen rather than the mineral phase, it is essential to identify new spectroscopic biomarkers that help infer the status of collagen quality. Amide I and amide III bands are uniquely useful for collagen conformational analysis. Thus, the first aim of this work was to identify the regions of amide bands that are sensitive to thermally induced denaturation. Collagen sheets and bone were thermally denatured to identify spectral measures that change significantly following denaturation. The second aim was to assess whether mechanical damage denatures the collagen phase of bone, as reflected by the molecular spectroscopic biomarkers identified in the first aim. The third aim was to assess the correlation between these new spectroscopic biomarkers and postyield mechanical properties of cortical bone. Our results revealed five peaks whose intensities were sensitive to thermal

Raman spectral classification of mineral- and collagen-bound water's associations to elastic and post-yield mechanical properties of cortical bone

Bone, Jan 26, 2015

Water that is bound to bone's matrix is implied as a predictor of fracture resistance; howeve... more Water that is bound to bone's matrix is implied as a predictor of fracture resistance; however, bound water is an elusive variable to be measured nondestructively. To date, the only nondestructive method used for studying bone hydration status is magnetic resonance variants (NMR or MRI). For the first time, bone hydration status was studied by short-wave infrared (SWIR) Raman spectroscopy to investigate associations of mineral-bound and collagen-bound water compartments with mechanical properties. Thirty cortical bone samples were used for quantitative Raman-based water analysis, gravimetric analysis, porosity measurement, and biomechanical testing. A sequential dehydration protocol was developed to replace unbound (heat drying) and bound (ethanol treatment) water in bone. Raman spectra were collected serially to track the OH-stretch band during dehydration. Four previously identified peaks were investigated: I3220/I2949, I3325/I2949 and I3453/I2949 reflect status of organic-mat...

Molecular spectroscopic identification of the water compartments in bone

Bone, 2014

Matrix bound water is a correlate of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp... more Matrix bound water is a correlate of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s fracture resistance and assessment of bound water is emerging as a novel measure of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s mechanical integrity. Raman spectroscopy is one of the few nondestructive modalities to assess the hydration status in bone; however, it has not been used to study the OH-band in bone. A sequential dehydration protocol was developed to replace unbound (heat drying) and bound (ethanol or deuterium) water in bone. Raman spectra were collected serially to track the OH-band during dehydration. Spectra of synthetic hydroxyapatite, demineralized bone and bulk water were collected to identify mineral and collagen contributions to the OH-band. Band assignments were supported by computational simulations of the molecular vibrations of Gly-Pro-Hyp amino acid sequence. Experimentally and theoretically obtained spectra were interpreted for band-assignments. Water loss was measured gravimetrically and correlated to Raman intensities. Four peaks were identified to be sensitive to dehydration: 3220cm(-1) (water), 3325cm(-1) (NH and water), 3453cm(-1) (hydroxyproline and water), and 3584cm(-1) (mineral and water). These peaks were differentially sensitive to deuterium treatment such that some water peaks were replaced with deuterium oxide faster than the rest. Specifically, the peaks at 3325 and 3584cm(-1) were more tightly bound to the matrix than the remaining bands. Comparison of dehydration in mineralized and demineralized bone revealed a volume of water that may be locked in the matrix by mineral crystals. The OH-range of bone was dominated by collagen and the water since the spectral profile of dehydrated demineralized bone was similar to that of the mineralized bone. Furthermore, water associates to bone mainly by collagen as findings of experimentally and theoretically spectra. The current work is among the first thorough analysis of the Raman OH stretch band in bone and such spectral information may be used to understand the involvement of water in the fragility of aging and in diseased bone.

Tasarımın Uzun Boyun Seramik Femoral Baş Protezinin Yüksek Kırılma Oranına Katkısının Sonlu Elemanlar Analizi ile Araştırılması

Academic Platform Journal of Engineering and Science, 2020

Üstün aşınma direncine sahip olan seramikler, genç hastaların femur başı protezi için en iyi malz... more Üstün aşınma direncine sahip olan seramikler, genç hastaların femur başı protezi için en iyi malzeme seçeneklerindendir. Bununla birlikte, seramiklerin doğal dezavantajları kırılganlıklarıdır. Bu nedenle, seramik femur başlarının üretim ve tasarım faktörleri dikkatlice düşünülmelidir. Aksi takdirde, yüksek kırılma oranına bağlı olarak, 2001 yılında seramik femoral başların geri çağrılması olayında olduğu gibi daha ciddi bir soruna neden olabilir. Her ne kadar geri çağrılan bu seramik başların yüksek kırılma oranları, temel olarak imalat işlemindeki bir değişiklikle ilişkilendirilmiş olsa da, aynı partide üretilen uzun boyun tasarımlı seramik başların neden kısa boyun tasarımlı seramik başlara göre daha yüksek kırılma oranına sahip oldukları konusunda kesin bir tespit yapılamamış ve bu konuda bir mekanik analiz bulunmamaktadır. Bu çalışmanın amacı, tasarım faktörünün uzun boyunlu seramik femoral başlarının daha yüksek kırılma oranına olası katkısını belirlemek için sonlu elemanlar analizi kullanılarak iki farklı seramik femur başı (kısa ve uzun boyunlu seramik baş) üzerindeki gerilme dağılımının analizini yapmaktır.28 mm çapındaki iki farklı şekilde (kısa ve uzun boyunlu) tasarlanmış seramik başlar, 85 yaşındaki bir insanın yürüme koşulu altında maruz kaldığı maksimum yük altında sonlu elemanlar analizi (SEA) ile gerilme dağılımı test edildi. Katı modellemesi yapılmış femur ve protezlere önce ağ örgüsü oluşturulmuş (~75000 düğüm ve ~50000 eleman) ve literatürden elde edilen malzeme özellikleri modele atanmıştır Solidworks simülasyonundan elde edilen SEA sonuçları, uzun boyunlu seramik başın konik-delik temas bölgesinde zaman içinde yorulma kırılmasına yol açabilecek yaklaşık 5 kat daha fazla lokal gerilme yoğunlaşmasının varlığını göstermiştir. Bu sonuç tasarım faktörünün, üretim kusurunun ötesinde uzun boyunlu seramik başların daha yüksek kırılma oranına katkıda bulunabileceğini göstermektedir. Bu nedenle, tasarım faktörleriyle alakalı olan seramik başlar üzerindeki bu tür lokal gerilme yoğunlaşma alanlarının varlığı, yeni seramik femur başlarının tasarımı ve üretimi sırasında daima dikkate alınmalıdır.

Manipulating the Amount and Structure of the Organic Matrix Affects the Water Compartments of Human Cortical Bone

JBMR Plus, 2019

Being predictors of the mechanical properties of human cortical bone, bound and pore water measur... more Being predictors of the mechanical properties of human cortical bone, bound and pore water measurements by magnetic resonance (MR) imaging are being developed for the clinical assessment of fracture risk. While pore water is a surrogate of cortical bone porosity, the determinants of bound water are unknown. Manipulation of organic matrix properties by oxidative deproteinization, thermal denaturation, or nonenzymatic glycation lowers bone toughness. Because bound water contributes to bone toughness, we hypothesized that each of these matrix manipulations affect bound water fraction (V bw /V bone). Immersing cadaveric bone samples in sodium hypochlorite (NaClO) for 96 hours did not affect tissue mineral density or cortical porosity, but rather decreased V bw /V bone and increased short-T 2 pore water signals as determined by 1 H nuclear MR relaxometry (1 H NMR). Moreover, the post treatment V bw / V bone linearly correlated with the remaining weight fraction of the organic matrix. Heating bone samples at 110°C, 120°C, 130°C, and then 140°C ($24 hours per temperature and rehydration for $24 hours before 1 H NMR analysis) did not affect V bw /V bone. After subsequently heating them at 200°C, V bw /V bone increased. Boiling bone samples followed by heating at 110°C, 120°C, and then 130°C in water under pressure (8 hours per temperature) had a similar effect on V bw /V bone. Raman spectroscopy analysis confirmed that the increase in V bw /V bone coincided with an increase in an Amide I subpeak ratio that is sensitive to changes in the helical structure of collagen I. Glycation of bone by ribose for 4 weeks, but not in glucose for 16 weeks, decreased V bw /V bone , although the effect was less pronounced than that of oxidative deproteinization or thermal denaturation. We propose that MR measurements of bound water reflect the amount of bone organic matrix and can be modulated by collagen I helicity and by sugar-derived post translational modifications of the matrix.

$Research paper thumbnail of Shortwave-infrared Raman spectroscopic classification of water fractions in articular cartilage ex vivo$

Shortwave-infrared Raman spectroscopic classification of water fractions in articular cartilage ex vivo

Journal of biomedical optics, 2018

Water loss is an early onset indicator of osteoarthritis. Although Raman spectroscopy (RS) holds ... more Water loss is an early onset indicator of osteoarthritis. Although Raman spectroscopy (RS) holds the potential for measurement of cartilage hydration, the knowledge of Raman OH-stretch bands of biological tissue is very limited. We assesed here the sensitivity of RS to identify and classify water types in the cartilage. Raman spectrum measurements over the high wavenumber range were employed to identify different water fractions in articular cartilage. Raman spectra were collected from wet and sequentially dehydrated cartilage along with pure collagen type II and chondroitin sulfate standards. OH-stretch band of cartilage is dominated by mobile water, up to 95% of total intensities. We identified six peaks in cartilage spectrum using second-derivative analysis: peaks at 3200 and 3650 cm-1 are associated with organic matrix (both collagen and proteglycan) and matrix-bound water molecules. Peaks at 3250, 3453, and 3630 cm-1 are associated with collagen and collagen-related water mol...

Assessing Glycation-mediated Changes in Human Cortical Bone with Raman Spectroscopy

Journal of biophotonics, Jan 25, 2018

Establishing a non-destructive method for spatially assessing advanced glycation end-products (AG... more Establishing a non-destructive method for spatially assessing advanced glycation end-products (AGEs) is a potentially useful step toward investigating the mechanistic role of AGEs in bone quality. To test the hypothesis that the shape of the Amide I in the Raman Spectroscopy (RS) analysis of bone matrix changes upon AGE accumulation, we incubated paired cadaveric cortical bone in ribose or glucose solutions and in control solutions for 4 and 16 weeks, respectively, at 37 °C. Acquiring 10 spectra per bone with a 20X objective and a 830 nm laser, RS was sensitive to AGE accumulation (confirmed by biochemical measurements of pentosidine and fluorescent AGEs). Hyp/Pro ratio increased upon glycation using either 0.1 M ribose, 0.5 M ribose, or 0.5 M glucose. Glycation also decreased the Amide I sub-peak ratios (cm) 1668/1638 and 1668/1610 when directly calculated using either second derivative spectrum or local maxima of difference spectrum, though the processing method (e.g., averaged sp...

Miniscrew biomechanics: Guidelines for the use of rigid indirect anchorage mechanics

American Journal of Orthodontics and Dentofacial Orthopedics, 2017

Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Althou... more Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Although there are different ways to set up the mechanics, rigid indirect anchorage offers the greatest biomechanical versatility but is more difficult to install than conventional, nonrigid indirect anchorage or direct anchorage. The purpose of this article was to introduce readers to the concept of rigid indirect anchorage and provide guidelines as to its use.

Effects of losartan treatment on the physicochemical properties of diabetic rat bone

Journal of Bone and Mineral Metabolism, 2016

Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to... more Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to be effective on bone tissue, suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may reduce fracture risk. The present study investigated the effects of losartan on the physicochemical and biomechanical properties of diabetic rat bone. Losartan (5 mg/kg/day) was administered via oral gavage for 12 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Whole femurs were tested under tension to evaluate the biomechanical properties of bone. The physicochemical properties of bone were analyzed by Fourier transform infrared spectroscopy. Although losartan did not recover decreases in the BMD of diabetic bone, it recovered the physicochemical (mineral and collagen matrix) properties of diabetic rat bone. Furthermore, losartan also recovered ultimate tensile strength of diabetic rat femurs. Losartan, an angiotensin II type 1 receptor blocker, has a therapeutic effect on the physicochemical properties of diabetic bone resulting in improvement of bone strength at the material level. Therefore, specific inhibition of this pathway at the receptor level shows potential as a therapeutic target for diabetic patients suffering from bone diseases such as osteopenia.

Micro and Nano-Scale Technologies for Cell Mechanics

Nanobiomedicine, 2014

Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and... more Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and micro and nanotechnology, which synergize to help us better understand the intricacies and the complex nature of cells in their native environment. With recent advances in nanotechnology, microfabrication methods and micro-electro-mechanical-systems (MEMS), we are now well situated to tap into the complex micro world of cells. The field that brings biology and MEMS together is known as Biological MEMS (BioMEMS). BioMEMS take advantage of systematic design and fabrication methods to create platforms that allow us to study cells like never before. These new technologies have been rapidly advancing the study of cell mechanics. This review article provides a succinct overview of cell mechanics and comprehensively surveys micro and nano-scale technologies that have been specifically developed for and are relevant to the mechanics of cells. Here we focus on micro and nano-scale technologies, ...

Raman spectroscopy-based water content is a negative predictor of articular human cartilage mechanical function

Osteoarthritis and Cartilage, 2018

Objective: Probing the change in water content is an emerging approach to assess early diagnosis ... more Objective: Probing the change in water content is an emerging approach to assess early diagnosis of osteoarthritis (OA). We herein developed a new method to assess hydration status of cartilage nondestructively using Raman spectroscopy (RS), and showed association of Raman-based water and organic content measurement with mechanical properties of cartilage. We further compared Raman-based water measurement to gravimetric and magnetic resonance imaging (MRI)-based water measurement. Design: Eighteen cadaveric human articular cartilage plugs from 6 donors were evenly divided into two age groups: young (n ¼ 9, mean age: 29.3 ± 6.6) and old (n ¼ 9, mean age: 64.0 ± 1.5). Water content in cartilage was measured using RS, gravimetric, and MRI-based techniques. Using confined compression creep test, permeability and aggregate modulus were calculated. Regression analyses were performed among RS parameters, MRI parameter, permeability, aggregate modulus and gravimetrically measured water content. Results: Regardless of the method used to calculate water content (gravimetric, RS and MRI), older cartilage group consistently had higher water content compared to younger group. There was a stronger association between gravimetric and RS-based water measurement (R 2 g ¼ 0.912) than between gravimetric and MRI-based water measurement (R 2 c ¼ 0.530). Gravimetric and RS-based water contents were significantly correlated with permeability and aggregate modulus whereas MRI-based water measurement was not. Conclusion: RS allows for quantification of different water compartments in cartilage nondestructively, and estimation of up to 82% of the variation observed in the permeability and aggregate modulus of articular cartilage. RS has the potential to be used clinically to monitor cartilage quality noninvasively or minimally invasively with Raman probe during arthroscopy procedures.

Collagen bound water is a strong correlate of bone's toughness

Compositional assessment of bone by Raman spectroscopy

The Analyst, 2021

Raman spectroscopy (RS) is used to analyze the physiochemical properties of bone because it is no... more

Constitutive activation of MEK1 in osteoprogenitors increases strength of bone despite impairing mineralization

Bone, 2019

Recent clinical studies have revealed that a somatic mutation in MAP2K1, causing constitutive act... more Recent clinical studies have revealed that a somatic mutation in MAP2K1, causing constitutive activation of MEK1 in osteogenic cells, occurs in melorheostotic bone disease in humans. We have generated a mouse model which expresses an activated form of MEK1 (MEK1DD) specifically in osteoprogenitors postnatally. The skeletal phenotype of these mice recapitulates many features of melorheostosis observed in humans, including extra-cortical bone formation, abundant osteoid formation, decreased mineral density, and increased porosity. Paradoxically, in both humans and mice, MEK1 activation in osteoprogenitors results in bone that is not structurally compromised, but is hardened and stronger, which would not be predicted based on tissue and matrix properties. Thus, a specific activating mutation in MEK1, expressed only by osteoprogenitors postnatally, can have a significant impact on bone strength through complex alterations in whole bone geometry, bone micro-structure, and bone matrix.

Low bone toughness in the TallyHO model of juvenile type 2 diabetes does not worsen with age

Bone, May 1, 2018

Fracture risk increases as type 2 diabetes (T2D) progresses. With the rising incidence of T2D, in... more Fracture risk increases as type 2 diabetes (T2D) progresses. With the rising incidence of T2D, in particular early-onset T2D, a representative pre-clinical model is needed to study mechanisms for treating or preventing diabetic bone disease. Towards that goal, we hypothesized that fracture resistance of bone from diabetic TallyHO mice decreases as the duration of diabetes increases. Femurs and lumbar vertebrae were harvested from male, TallyHO mice and male, non-diabetic SWR/J mice at 16weeks (n≥12 per strain) and 34weeks (n≥13 per strain) of age. As is characteristic of this model of juvenile T2D, the TallyHO mice were obese and hyperglycemic at an early age (5weeks and 10weeks of age, respectively). The femur mid-shaft of TallyHO mice had higher tissue mineral density and larger cortical area, as determined by micro-computed tomography, compared to the femur mid-shaft of SWR/J mice, irrespective of age. As such, the diabetic rodent bone was structurally stronger than the non-diabe...

The Role of Matrix Composition in the Mechanical Behavior of Bone

Current osteoporosis reports, Jan 3, 2018

While thinning of the cortices or trabeculae weakens bone, age-related changes in matrix composit... more While thinning of the cortices or trabeculae weakens bone, age-related changes in matrix composition also lower fracture resistance. This review summarizes how the organic matrix, mineral phase, and water compartments influence the mechanical behavior of bone, thereby identifying characteristics important to fracture risk. In the synthesis of the organic matrix, tropocollagen experiences various post-translational modifications that facilitate a highly organized fibril of collagen I with a preferred orientation giving bone extensibility and several toughening mechanisms. Being a ceramic, mineral is brittle but increases the strength of bone as its content within the organic matrix increases. With time, hydroxyapatite-like crystals experience carbonate substitutions, the consequence of which remains to be understood. Water participates in hydrogen bonding with organic matrix and in electrostatic attractions with mineral phase, thereby providing stability to collagen-mineral interface...

Chemical characterization of Maltese-cross birefringent particles in synovial fluid samples collected from symptomatic joints

Joint, bone, spine : revue du rhumatisme, Jan 28, 2017

Interrelationships between electrical, mechanical and hydration properties of cortical bone

Journal of the Mechanical Behavior of Biomedical Materials, 2018

Interrelationship between electrical and mechanical properties of cortical bone and the role of b... more Interrelationship between electrical and mechanical properties of cortical bone and the role of bone composition in this interrelationship are not comprehensively investigated to date. This study aimed to investigate associations of electrical properties (i.e., specific impedance, dielectric constant, and conductivity) with mechanical properties (i.e., toughness, strength and elastic modulus) of wet and sequentially dehydrated cortical bone. Bovine cortical bone samples (N = 24) were subjected to three-point bending test. A sequential heat treatment protocol ensued to tease out contributions of unbound water and bound water. Demineralization was performed to understand contributions of organic matrix and the mineral phase to the electrical properties of cortical bone. Raman-spectroscopy based water measurement was used to investigate involvement of collagen-and mineralbound water in the electrical properties. Our results showed statistically significant correlations between electrical and mechanical properties of cortical bone. Toughness and ultimate strength were negatively correlated with impedance and positively correlated with conductivity and dielectric constant. The highest correlations between electrical and mechanical properties of cortical bone were typically found at the frequencies of 0.2, 0.5 and 1 MHz. The electrical properties of bone changed significantly as a result of sequential dehydration, indicating that unbound and bound water compartments are the key determinants of the electrical properties. Comparison of porosity matched bone samples with high and low amount of bound water showed that bound water compartments may have an independent role in determining electrical properties of cortical bone. Furthermore, the results indicated that collagen and mineral-bound water may contribute differentially to the electrical properties of a bone. In the overall, our results suggest that electrical properties of cortical bone may be used to assess bone toughness and strength, and also underline the necessity for developing techniques to measure these electrical properties in vivo.

Repetitive short-span application of extracellular calcium is osteopromotive to osteoprogenitor cells

Journal of tissue engineering and regenerative medicine, Jan 17, 2017

Extracellular calcium ([Ca(2+) ]E ) concentration has been suggested to stimulate osteoblastic ac... more Extracellular calcium ([Ca(2+) ]E ) concentration has been suggested to stimulate osteoblastic activity; thus, calcium can be used to enhance fracture healing. However, systemic administration of calcium at high dose levels may cause physiological problems such as hypercalcemia. Short span application of single or repetitive [Ca(2+) ]E stimulus may be suggested as a novel regimen to reduce such side effects. However, osteopromotive effect of such short term [Ca(2+) ]E stimulus on osteoprogenitor cells has not yet been evaluated yet. This study investigated the effects of [Ca(2+) ]E dose (6 mM and 18 mM) and regimen (single, repetitive and continuous) on viability, proliferation, osteogenic gene expression and mineral formation by osteoprogenitor cells. BMP-2 treatment was set as the positive control group. It was observed that repetitive and continuous calcium stimulation resulted in significant enhancement of osteoblastic activity. 6 mM [Ca(2+) ]E significantly increased cell viabi...

Raman spectral markers of collagen denaturation and hydration in human cortical bone tissue are affected by radiation sterilization and high cycle fatigue damage

Journal of the mechanical behavior of biomedical materials, Nov 13, 2017

Thermal denaturation and monotonic mechanical damage alter the organic and water-related compartm... more Thermal denaturation and monotonic mechanical damage alter the organic and water-related compartments of cortical bone. These changes can be detected using Raman spectroscopy. However, less is known regarding Raman sensitivity to detect the effects of cyclic fatigue damage and allograft sterilization doses of gamma radiation. To determine if Raman spectroscopic biomarkers of collagen denaturation and hydration are sensitive to the effects of (a) high cycle fatigue damage and (b) 25kGy irradiation. Unirradiated and gamma-radiation sterilized human cortical bone specimens previously tested in vitro under high-cycle (> 100,000 cycles) fatigue conditions at 15MPa, 25MPa, 35MPa, 45MPa, and 55MPa cyclic stress levels were studied. Cortical bone Raman spectral profiles from wavenumber ranges of 800-1750cm(-1) and 2700-3800cm(-1) were obtained and compared from: a) non-fatigue vs fatigue fracture sites and b) radiated vs. unirradiated states. Raman biomarker ratios 1670/1640 and 3220/294...

Novel Raman Spectroscopic Biomarkers Indicate That Postyield Damage Denatures Bone's Collagen

Journal of Bone and Mineral Research, 2016

Raman spectroscopy has become a powerful tool in the assessment of bone quality. However, the use... more Raman spectroscopy has become a powerful tool in the assessment of bone quality. However, the use of Raman spectroscopy to assess collagen quality in bone is less established than mineral quality. Because postyield mechanical properties of bone are mostly determined by collagen rather than the mineral phase, it is essential to identify new spectroscopic biomarkers that help infer the status of collagen quality. Amide I and amide III bands are uniquely useful for collagen conformational analysis. Thus, the first aim of this work was to identify the regions of amide bands that are sensitive to thermally induced denaturation. Collagen sheets and bone were thermally denatured to identify spectral measures that change significantly following denaturation. The second aim was to assess whether mechanical damage denatures the collagen phase of bone, as reflected by the molecular spectroscopic biomarkers identified in the first aim. The third aim was to assess the correlation between these new spectroscopic biomarkers and postyield mechanical properties of cortical bone. Our results revealed five peaks whose intensities were sensitive to thermal

Raman spectral classification of mineral- and collagen-bound water's associations to elastic and post-yield mechanical properties of cortical bone

Bone, Jan 26, 2015

Water that is bound to bone's matrix is implied as a predictor of fracture resistance; howeve... more Water that is bound to bone's matrix is implied as a predictor of fracture resistance; however, bound water is an elusive variable to be measured nondestructively. To date, the only nondestructive method used for studying bone hydration status is magnetic resonance variants (NMR or MRI). For the first time, bone hydration status was studied by short-wave infrared (SWIR) Raman spectroscopy to investigate associations of mineral-bound and collagen-bound water compartments with mechanical properties. Thirty cortical bone samples were used for quantitative Raman-based water analysis, gravimetric analysis, porosity measurement, and biomechanical testing. A sequential dehydration protocol was developed to replace unbound (heat drying) and bound (ethanol treatment) water in bone. Raman spectra were collected serially to track the OH-stretch band during dehydration. Four previously identified peaks were investigated: I3220/I2949, I3325/I2949 and I3453/I2949 reflect status of organic-mat...

Molecular spectroscopic identification of the water compartments in bone

Bone, 2014

Matrix bound water is a correlate of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp... more Matrix bound water is a correlate of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s fracture resistance and assessment of bound water is emerging as a novel measure of bone&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s mechanical integrity. Raman spectroscopy is one of the few nondestructive modalities to assess the hydration status in bone; however, it has not been used to study the OH-band in bone. A sequential dehydration protocol was developed to replace unbound (heat drying) and bound (ethanol or deuterium) water in bone. Raman spectra were collected serially to track the OH-band during dehydration. Spectra of synthetic hydroxyapatite, demineralized bone and bulk water were collected to identify mineral and collagen contributions to the OH-band. Band assignments were supported by computational simulations of the molecular vibrations of Gly-Pro-Hyp amino acid sequence. Experimentally and theoretically obtained spectra were interpreted for band-assignments. Water loss was measured gravimetrically and correlated to Raman intensities. Four peaks were identified to be sensitive to dehydration: 3220cm(-1) (water), 3325cm(-1) (NH and water), 3453cm(-1) (hydroxyproline and water), and 3584cm(-1) (mineral and water). These peaks were differentially sensitive to deuterium treatment such that some water peaks were replaced with deuterium oxide faster than the rest. Specifically, the peaks at 3325 and 3584cm(-1) were more tightly bound to the matrix than the remaining bands. Comparison of dehydration in mineralized and demineralized bone revealed a volume of water that may be locked in the matrix by mineral crystals. The OH-range of bone was dominated by collagen and the water since the spectral profile of dehydrated demineralized bone was similar to that of the mineralized bone. Furthermore, water associates to bone mainly by collagen as findings of experimentally and theoretically spectra. The current work is among the first thorough analysis of the Raman OH stretch band in bone and such spectral information may be used to understand the involvement of water in the fragility of aging and in diseased bone.

Tasarımın Uzun Boyun Seramik Femoral Baş Protezinin Yüksek Kırılma Oranına Katkısının Sonlu Elemanlar Analizi ile Araştırılması

Academic Platform Journal of Engineering and Science, 2020

Üstün aşınma direncine sahip olan seramikler, genç hastaların femur başı protezi için en iyi malz... more Üstün aşınma direncine sahip olan seramikler, genç hastaların femur başı protezi için en iyi malzeme seçeneklerindendir. Bununla birlikte, seramiklerin doğal dezavantajları kırılganlıklarıdır. Bu nedenle, seramik femur başlarının üretim ve tasarım faktörleri dikkatlice düşünülmelidir. Aksi takdirde, yüksek kırılma oranına bağlı olarak, 2001 yılında seramik femoral başların geri çağrılması olayında olduğu gibi daha ciddi bir soruna neden olabilir. Her ne kadar geri çağrılan bu seramik başların yüksek kırılma oranları, temel olarak imalat işlemindeki bir değişiklikle ilişkilendirilmiş olsa da, aynı partide üretilen uzun boyun tasarımlı seramik başların neden kısa boyun tasarımlı seramik başlara göre daha yüksek kırılma oranına sahip oldukları konusunda kesin bir tespit yapılamamış ve bu konuda bir mekanik analiz bulunmamaktadır. Bu çalışmanın amacı, tasarım faktörünün uzun boyunlu seramik femoral başlarının daha yüksek kırılma oranına olası katkısını belirlemek için sonlu elemanlar analizi kullanılarak iki farklı seramik femur başı (kısa ve uzun boyunlu seramik baş) üzerindeki gerilme dağılımının analizini yapmaktır.28 mm çapındaki iki farklı şekilde (kısa ve uzun boyunlu) tasarlanmış seramik başlar, 85 yaşındaki bir insanın yürüme koşulu altında maruz kaldığı maksimum yük altında sonlu elemanlar analizi (SEA) ile gerilme dağılımı test edildi. Katı modellemesi yapılmış femur ve protezlere önce ağ örgüsü oluşturulmuş (~75000 düğüm ve ~50000 eleman) ve literatürden elde edilen malzeme özellikleri modele atanmıştır Solidworks simülasyonundan elde edilen SEA sonuçları, uzun boyunlu seramik başın konik-delik temas bölgesinde zaman içinde yorulma kırılmasına yol açabilecek yaklaşık 5 kat daha fazla lokal gerilme yoğunlaşmasının varlığını göstermiştir. Bu sonuç tasarım faktörünün, üretim kusurunun ötesinde uzun boyunlu seramik başların daha yüksek kırılma oranına katkıda bulunabileceğini göstermektedir. Bu nedenle, tasarım faktörleriyle alakalı olan seramik başlar üzerindeki bu tür lokal gerilme yoğunlaşma alanlarının varlığı, yeni seramik femur başlarının tasarımı ve üretimi sırasında daima dikkate alınmalıdır.

Manipulating the Amount and Structure of the Organic Matrix Affects the Water Compartments of Human Cortical Bone

JBMR Plus, 2019

Being predictors of the mechanical properties of human cortical bone, bound and pore water measur... more Being predictors of the mechanical properties of human cortical bone, bound and pore water measurements by magnetic resonance (MR) imaging are being developed for the clinical assessment of fracture risk. While pore water is a surrogate of cortical bone porosity, the determinants of bound water are unknown. Manipulation of organic matrix properties by oxidative deproteinization, thermal denaturation, or nonenzymatic glycation lowers bone toughness. Because bound water contributes to bone toughness, we hypothesized that each of these matrix manipulations affect bound water fraction (V bw /V bone). Immersing cadaveric bone samples in sodium hypochlorite (NaClO) for 96 hours did not affect tissue mineral density or cortical porosity, but rather decreased V bw /V bone and increased short-T 2 pore water signals as determined by 1 H nuclear MR relaxometry (1 H NMR). Moreover, the post treatment V bw / V bone linearly correlated with the remaining weight fraction of the organic matrix. Heating bone samples at 110°C, 120°C, 130°C, and then 140°C ($24 hours per temperature and rehydration for $24 hours before 1 H NMR analysis) did not affect V bw /V bone. After subsequently heating them at 200°C, V bw /V bone increased. Boiling bone samples followed by heating at 110°C, 120°C, and then 130°C in water under pressure (8 hours per temperature) had a similar effect on V bw /V bone. Raman spectroscopy analysis confirmed that the increase in V bw /V bone coincided with an increase in an Amide I subpeak ratio that is sensitive to changes in the helical structure of collagen I. Glycation of bone by ribose for 4 weeks, but not in glucose for 16 weeks, decreased V bw /V bone , although the effect was less pronounced than that of oxidative deproteinization or thermal denaturation. We propose that MR measurements of bound water reflect the amount of bone organic matrix and can be modulated by collagen I helicity and by sugar-derived post translational modifications of the matrix.

$Research paper thumbnail of Shortwave-infrared Raman spectroscopic classification of water fractions in articular cartilage ex vivo$

Shortwave-infrared Raman spectroscopic classification of water fractions in articular cartilage ex vivo

Journal of biomedical optics, 2018

Water loss is an early onset indicator of osteoarthritis. Although Raman spectroscopy (RS) holds ... more Water loss is an early onset indicator of osteoarthritis. Although Raman spectroscopy (RS) holds the potential for measurement of cartilage hydration, the knowledge of Raman OH-stretch bands of biological tissue is very limited. We assesed here the sensitivity of RS to identify and classify water types in the cartilage. Raman spectrum measurements over the high wavenumber range were employed to identify different water fractions in articular cartilage. Raman spectra were collected from wet and sequentially dehydrated cartilage along with pure collagen type II and chondroitin sulfate standards. OH-stretch band of cartilage is dominated by mobile water, up to 95% of total intensities. We identified six peaks in cartilage spectrum using second-derivative analysis: peaks at 3200 and 3650 cm-1 are associated with organic matrix (both collagen and proteglycan) and matrix-bound water molecules. Peaks at 3250, 3453, and 3630 cm-1 are associated with collagen and collagen-related water mol...

Assessing Glycation-mediated Changes in Human Cortical Bone with Raman Spectroscopy

Journal of biophotonics, Jan 25, 2018

Establishing a non-destructive method for spatially assessing advanced glycation end-products (AG... more Establishing a non-destructive method for spatially assessing advanced glycation end-products (AGEs) is a potentially useful step toward investigating the mechanistic role of AGEs in bone quality. To test the hypothesis that the shape of the Amide I in the Raman Spectroscopy (RS) analysis of bone matrix changes upon AGE accumulation, we incubated paired cadaveric cortical bone in ribose or glucose solutions and in control solutions for 4 and 16 weeks, respectively, at 37 °C. Acquiring 10 spectra per bone with a 20X objective and a 830 nm laser, RS was sensitive to AGE accumulation (confirmed by biochemical measurements of pentosidine and fluorescent AGEs). Hyp/Pro ratio increased upon glycation using either 0.1 M ribose, 0.5 M ribose, or 0.5 M glucose. Glycation also decreased the Amide I sub-peak ratios (cm) 1668/1638 and 1668/1610 when directly calculated using either second derivative spectrum or local maxima of difference spectrum, though the processing method (e.g., averaged sp...

Miniscrew biomechanics: Guidelines for the use of rigid indirect anchorage mechanics

American Journal of Orthodontics and Dentofacial Orthopedics, 2017

Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Althou... more Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Although there are different ways to set up the mechanics, rigid indirect anchorage offers the greatest biomechanical versatility but is more difficult to install than conventional, nonrigid indirect anchorage or direct anchorage. The purpose of this article was to introduce readers to the concept of rigid indirect anchorage and provide guidelines as to its use.

Effects of losartan treatment on the physicochemical properties of diabetic rat bone

Journal of Bone and Mineral Metabolism, 2016

Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to... more Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to be effective on bone tissue, suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may reduce fracture risk. The present study investigated the effects of losartan on the physicochemical and biomechanical properties of diabetic rat bone. Losartan (5 mg/kg/day) was administered via oral gavage for 12 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Whole femurs were tested under tension to evaluate the biomechanical properties of bone. The physicochemical properties of bone were analyzed by Fourier transform infrared spectroscopy. Although losartan did not recover decreases in the BMD of diabetic bone, it recovered the physicochemical (mineral and collagen matrix) properties of diabetic rat bone. Furthermore, losartan also recovered ultimate tensile strength of diabetic rat femurs. Losartan, an angiotensin II type 1 receptor blocker, has a therapeutic effect on the physicochemical properties of diabetic bone resulting in improvement of bone strength at the material level. Therefore, specific inhibition of this pathway at the receptor level shows potential as a therapeutic target for diabetic patients suffering from bone diseases such as osteopenia.

Micro and Nano-Scale Technologies for Cell Mechanics

Nanobiomedicine, 2014

Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and... more Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and micro and nanotechnology, which synergize to help us better understand the intricacies and the complex nature of cells in their native environment. With recent advances in nanotechnology, microfabrication methods and micro-electro-mechanical-systems (MEMS), we are now well situated to tap into the complex micro world of cells. The field that brings biology and MEMS together is known as Biological MEMS (BioMEMS). BioMEMS take advantage of systematic design and fabrication methods to create platforms that allow us to study cells like never before. These new technologies have been rapidly advancing the study of cell mechanics. This review article provides a succinct overview of cell mechanics and comprehensively surveys micro and nano-scale technologies that have been specifically developed for and are relevant to the mechanics of cells. Here we focus on micro and nano-scale technologies, ...

Raman spectroscopy-based water content is a negative predictor of articular human cartilage mechanical function

Osteoarthritis and Cartilage, 2018

Objective: Probing the change in water content is an emerging approach to assess early diagnosis ... more Objective: Probing the change in water content is an emerging approach to assess early diagnosis of osteoarthritis (OA). We herein developed a new method to assess hydration status of cartilage nondestructively using Raman spectroscopy (RS), and showed association of Raman-based water and organic content measurement with mechanical properties of cartilage. We further compared Raman-based water measurement to gravimetric and magnetic resonance imaging (MRI)-based water measurement. Design: Eighteen cadaveric human articular cartilage plugs from 6 donors were evenly divided into two age groups: young (n ¼ 9, mean age: 29.3 ± 6.6) and old (n ¼ 9, mean age: 64.0 ± 1.5). Water content in cartilage was measured using RS, gravimetric, and MRI-based techniques. Using confined compression creep test, permeability and aggregate modulus were calculated. Regression analyses were performed among RS parameters, MRI parameter, permeability, aggregate modulus and gravimetrically measured water content. Results: Regardless of the method used to calculate water content (gravimetric, RS and MRI), older cartilage group consistently had higher water content compared to younger group. There was a stronger association between gravimetric and RS-based water measurement (R 2 g ¼ 0.912) than between gravimetric and MRI-based water measurement (R 2 c ¼ 0.530). Gravimetric and RS-based water contents were significantly correlated with permeability and aggregate modulus whereas MRI-based water measurement was not. Conclusion: RS allows for quantification of different water compartments in cartilage nondestructively, and estimation of up to 82% of the variation observed in the permeability and aggregate modulus of articular cartilage. RS has the potential to be used clinically to monitor cartilage quality noninvasively or minimally invasively with Raman probe during arthroscopy procedures.