Background: Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the... more Background: Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the principal load or if metallic, they can support loading, but can lead to stress shielding and are unable to integrate fully. In this study, we developed biocompatible, 3D printed scaffolds derived from µCT images of the bone that can overcome these issues and support the growth of osteoblasts. Methods: Cylindrical scaffolds were fabricated with acrylonitrile butadiene styrene (ABS) and Stratasys® MED 610 (MED610) materials. The 3D-printed scaffolds were seeded with Mus musculus calvaria cells (MC3T3). After the cells attained confluence, osteogenesis was induced with and without the addition of calcitonin receptor fragment peptide (CRFP) and the bone matrix production was analyzed. Mechanical compression testing was carried out to measure compressive strength, stiffness, and elastic modulus. Results: For the ABS scaffolds, there was a 9.8% increase in compressive strength (p < 0.05) ...
Gout is an inflammatory arthritis, which causes intense, acute pain due to the buildup of uric ac... more Gout is an inflammatory arthritis, which causes intense, acute pain due to the buildup of uric acid crystals in synovial fluid. The gold standard for gout diagnosis consists of synovial fluid analysis by polarized light microscopy, which is costly, time-intensive, and technique-dependent, therefore meriting a more efficient, inexpensive, and accessible method for diagnosis. We previously developed and validated a novel colorimetric gout detection method and device based on the reduction of silver nitrate by uric acid; here, we clinically validated our method and device using arthroscopically obtained synovial fluid samples from gout patients. We successfully identified uric acid crystals in clinical samples via our colorimetric method, visualized uric acid crystals in synovial fluid via handheld microscopy, and determined that silver nitrate stain did not interfere with the microscopic visualization of uric acid crystals necessary for diagnosis. We also developed and validated a met...
Introduction: During the height of the COVID-19 pandemic in New York, hip fractures requiring ope... more Introduction: During the height of the COVID-19 pandemic in New York, hip fractures requiring operative management continued to present to Stony Brook University Hospital. Given the novelty of SARS-CoV-2, there is recent interest in the pandemic and its relationship to orthopedic operative outcomes. This retrospective cohort study compared outcomes for operative hip fractures in patients prior to and during the COVID-19 pandemic at a level 1 academic center. Materials and Methods: Data was collected on patients age 18 years or older who underwent operative management for hip fractures performed from January 21, 2019 to July 1, 2019 (pre-pandemic) or from January 21, 2020 to July 1, 2020 (pandemic). COVID-19 status, demographics and outcomes were analyzed. Results: Overall, 159 patients with hip fractures were included in this study, 103 in the 2019 group and 56 in the 2020 group. Within the 2019 group, there was a significantly greater proportion of female patients compared to 2020 ...
Introduction: Methylphenidate (MP) is a widely used psychostimulant prescribed for Attention Defi... more Introduction: Methylphenidate (MP) is a widely used psychostimulant prescribed for Attention Deficit Hyperactivity Disorder, and is also used illicitly by healthy individuals. Chronic exposure to MP has been shown to affect physiology, behavior, and neurochemistry. Methods: The present study examined its effect on the endocannabinoid system. Adolescent rats had daily oral access to either water (control), low dose MP (4/10 mg/kg), or high dose MP (30/60 mg/kg). After 13 weeks of exposure, half of the rats in each group were euthanized, however the remaining rats underwent a four-week long abstinence period. Cannabinoid receptor 1 binding (CB1) was measured with in vitro autoradiography using [3H] SR141716A. Results: Rats who underwent a 4-week abstinence period after exposure to chronic HD MP showed increased binding compared to rats with no abstinence period in several cortical and basal ganglia regions of the brain. In contrast to this, rats who underwent a 4-week abstinence perio...
Purpose To use serial PET/MRI imaging to radiographically evaluate the metabolic activity of the ... more Purpose To use serial PET/MRI imaging to radiographically evaluate the metabolic activity of the ACL graft over the first post-operative year. Methods Six patients undergoing primary ACL reconstruction were recruited in this prospective study in an inpatient university hospital. All patients underwent femoral and tibial suspensory cortical fixation with quadrupled semitendinosus autograft hamstring ACL reconstruction by an orthopaedic surgeon. Simultaneous 18F-FDG PET and MRI of both the operative and non-operative knee was performed at three, six, and 12 months post-operatively. Quantification of the mean standardized uptake value (SUV) within the whole-knee, as well as tibial tunnel, femoral tunnel, and intra-articular graft regions of interest (ROIs). Results PET whole-knee activity was increased at all time-points post-operatively compared to the control, non-operative knee. Activity decreased over time, yet considerable generalized activity remained 1 year post-operatively, wit...
Gout is a form of arthritis characterized by buildup of uric acid in synovial fluid, which causes... more Gout is a form of arthritis characterized by buildup of uric acid in synovial fluid, which causes severe swelling and can harm joints, tendons, and other tissues. It affects approximately 4% of the United States population, or approximately 8.3 million people nationwide and is therefore a topic of epidemiologic consideration due to its prevalence. Gout is typically diagnosed via polarized microscopy of arthroscopically-aspirated synovial fluid, which is a costly, time-consuming, labor-intensive, and technically complex procedure, warranting a simpler and less complex method for diagnosis. Here, we propose and validate a colorimetric method which is based on the ability of uric acid to reduce silver nitrate. We also assessed how the colorimetric change can be accelerated by changing the concentration of silver nitrate or adding different silver catalysts, as well as develop a matrix bed for improved handling and ease of use. When translated to the clinic, this diagnostic method for g...
Scaffold design plays an essential role in tissue engineering of articular cartilage by providing... more Scaffold design plays an essential role in tissue engineering of articular cartilage by providing the appropriate mechanical and biological environment for chondrocytes to proliferate and function. Optimization of scaffold design to generate tissue-engineered cartilage has traditionally been conducted using in-vitro and in-vivo models. Recent advances in computational analysis allow us to significantly decrease the time and cost of scaffold optimization using finite element analysis (FEA). FEA is an in-silico analysis technique that allows for scaffold design optimization by predicting mechanical responses of cells and scaffolds under applied loads. Finite element analyses can potentially mimic the morphology of cartilage using mesh elements (tetrahedral, hexahedral), material properties (elastic, hyperelastic, poroelastic, composite), physiological loads by applying loading conditions (static, dynamic), and constitutive stress–strain equations (linear, porous–elastic, biphasic). Fu...
Background Existing ultrashort echo time magnetic resonance imaging (UTE MRI) methods require pro... more Background Existing ultrashort echo time magnetic resonance imaging (UTE MRI) methods require prohibitively long acquisition times (~ 20–40 min) to quantitatively assess the clinically relevant fast decay T2* component in ligaments and tendons. The purpose of this study was to evaluate the feasibility and clinical translatability of a novel abbreviated quantitative UTE MRI paradigm for monitoring graft remodeling after anterior cruciate ligament (ACL) reconstruction. Methods Eight patients who had Graftlink™ hamstring autograft reconstruction were recruited for this prospective study. A 3D double-echo UTE sequence at 3.0 Tesla was performed at 3- and 6-months post-surgery. An abbreviated UTE MRI paradigm was established based on numerical simulations and in vivo validation from healthy knees. This proposed approach was used to assess the T2* for fast decay component ($$ {T}_{2s}^{\ast } $$ T 2 s ∗ ) and bound water signal fraction (fbw) of ACL graft in regions of interest drawn by a...
Purpose: Although surgical repair of distal biceps tendon rupture improves functional outcomes co... more Purpose: Although surgical repair of distal biceps tendon rupture improves functional outcomes compared with nonsurgical treatments, the choice of operative technique remains a matter of preference. This study retrospectively examined outcomes from a repair technique using a volar distal biceps reinsertion secured with a unicortical intramedullary button in the proximal radial tuberosity to determine its safety and functional outcomes. Methods: A single fellowship-trained shoulder and elbow surgeon treated 27 men, average age 48 years (range, 25e66 years), between 2012 and 2016. Patient-reported outcomes included the Disabilities of the Arm, Shoulder, and Hand and American Shoulder and Elbow Surgeons (ASES) satisfaction scores and the Mayo Elbow Performance Score. Average patient follow-up was 24 months. Results: This series had an overall complication rate of 39.3% (11 of 28): 9 lateral antebrachial cutaneous neuropraxias, one radial sensory nerve irritation, and one superficial infection. No complications of peripheral nerve injury, proximal radioulnar synostosis, or rerupture were observed. Results (mean ± SD) demonstrated low disability (Disabilities of the Arm, Shoulder, and Hand score ¼ 2.9 ± 5.3), high satisfaction (American Shoulder and Elbow Surgeons score ¼ 9.3 ± 1.4), and acceptable performance (Mayo Elbow Performance Score ¼ 97.7 ± 6.3). Subcategory analysis identified a correlation between time to surgery and complications. Disability scores were higher in patients with workers' compensation claims versus private insurance (mean, 11.0 vs 1.1). Conclusions: Further trials are required to compare the results and complication rates of this unicortical intramedullary button procedure with other established methods. Type of study/level of evidence: Therapeutic IV.
The purpose of this study was to determine if a Sawbones Scoliosis Model could be used as a simul... more The purpose of this study was to determine if a Sawbones Scoliosis Model could be used as a simulator to train residents in placing pedicle screws-a complex procedure with a steep learning curve. Surgical simulation, a common tool teaching residents complex procedures in a safe environment, was staged using a Sawbones Scoliosis Model. Ten junior and ten senior residents out of 25 total possible residents (80%) were instructed how to place pedicle screws using the free-hand technique. They were then asked to place them unilaterally from T4 to L4 and were assessed on completion time, accuracy placement accuracy, and overall competency using an objective rating scale. Senior residents had an average time to completion of 38.9 ± 4.7 min vs. junior's 50.1 ± 11.7 min, and a pedicle screw accuracy of 43.6 ± 6.4% vs. junior's 44.4 ± 17.4%. Overall competency scores were similar for both groups; however, senior residents scored higher in the time and motion subdomain. Senior resident...
Journal of orthopaedic surgery and research, Jan 22, 2017
One of the major challenges in orthopedics is to develop implants that overcome current postopera... more One of the major challenges in orthopedics is to develop implants that overcome current postoperative problems such as osteointegration, proper load bearing, and stress shielding. Current implant techniques such as allografts or endoprostheses never reach full bone integration, and the risk of fracture due to stress shielding is a major concern. To overcome this, a novel technique of reverse engineering to create artificial scaffolds was designed and tested. The purpose of the study is to create a new generation of implants that are both biocompatible and biomimetic. 3D-printed scaffolds based on physiological trabecular bone patterning were printed. MC3T3 cells were cultured on these scaffolds in osteogenic media, with and without the addition of Calcitonin Receptor Fragment Peptide (CRFP) in order to assess bone formation on the surfaces of the scaffolds. Integrity of these cell-seeded bone-coated scaffolds was tested for their mechanical strength. The results show that cellular p...
We present a surgical strategy to manage multicolumnar tibial plateau fracture variants by addres... more We present a surgical strategy to manage multicolumnar tibial plateau fracture variants by addressing the predominant posterior fragment employing a Lobenhoffer approach in the prone position followed by supine patient repositioning for anterolateral column access. Multicenter retrospective analysis. Three academic Level 1 trauma centers. Twenty-eight cases (28 patients/28 knees) met inclusion criteria between 2003 and 2014. Patient demographic information was retrospectively reviewed with a mean follow-up time of 16.6 months (range 12-34 months). Postoperative radiographic analysis, physical examination findings, and patient outcome scores from the Knee Injury and Osteoarthritis Outcome Score questionnaire were recorded. The average time to union was 3.6 months (range 3-9 months). Eighty-two percent of patients had satisfactory articular reduction (less than 2 mm articular step off). All patients demonstrated satisfactory coronal (medial proximal tibia angle 87 ± 5 degrees) and sag...
Methylphenidate (MP) is the most prescribed psychostimulant for ADHD patients, with clinically de... more Methylphenidate (MP) is the most prescribed psychostimulant for ADHD patients, with clinically demonstrated detrimental effects on bone quality, potentially leading to early onset osteoporosis and higher fracture risk. The underlying mechanism for the effects of MP on bone remains elusive. This study demonstrates that sex- and dose-dependent effects of MP on bone quality and quantity are mediated by osteoclast activity. Four-week-old male and female rats were treated with low and high dose MP for 13 weeks. Bone quality and quantity were analyzed using microCT, mechanical testing, histomorphometry, and TRAP staining. Male and female rat bone marrow-derived osteoclasts were treated in a dose-dependent manner (0-1000 ng/ml) and osteoclast activity was determined at days 5, 7, and 14 using TRAP staining, as well as a pit formation assay at day 18. Animal studies showed a dose- and a sex-dependent decrease in mechanical integrity in femora and increased TRAP staining in MP-treated rats. ...
Background: Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the... more Background: Currently used synthetic bone graft substitutes (BGS) are either too weak to bear the principal load or if metallic, they can support loading, but can lead to stress shielding and are unable to integrate fully. In this study, we developed biocompatible, 3D printed scaffolds derived from µCT images of the bone that can overcome these issues and support the growth of osteoblasts. Methods: Cylindrical scaffolds were fabricated with acrylonitrile butadiene styrene (ABS) and Stratasys® MED 610 (MED610) materials. The 3D-printed scaffolds were seeded with Mus musculus calvaria cells (MC3T3). After the cells attained confluence, osteogenesis was induced with and without the addition of calcitonin receptor fragment peptide (CRFP) and the bone matrix production was analyzed. Mechanical compression testing was carried out to measure compressive strength, stiffness, and elastic modulus. Results: For the ABS scaffolds, there was a 9.8% increase in compressive strength (p < 0.05) ...
Gout is an inflammatory arthritis, which causes intense, acute pain due to the buildup of uric ac... more Gout is an inflammatory arthritis, which causes intense, acute pain due to the buildup of uric acid crystals in synovial fluid. The gold standard for gout diagnosis consists of synovial fluid analysis by polarized light microscopy, which is costly, time-intensive, and technique-dependent, therefore meriting a more efficient, inexpensive, and accessible method for diagnosis. We previously developed and validated a novel colorimetric gout detection method and device based on the reduction of silver nitrate by uric acid; here, we clinically validated our method and device using arthroscopically obtained synovial fluid samples from gout patients. We successfully identified uric acid crystals in clinical samples via our colorimetric method, visualized uric acid crystals in synovial fluid via handheld microscopy, and determined that silver nitrate stain did not interfere with the microscopic visualization of uric acid crystals necessary for diagnosis. We also developed and validated a met...
Introduction: During the height of the COVID-19 pandemic in New York, hip fractures requiring ope... more Introduction: During the height of the COVID-19 pandemic in New York, hip fractures requiring operative management continued to present to Stony Brook University Hospital. Given the novelty of SARS-CoV-2, there is recent interest in the pandemic and its relationship to orthopedic operative outcomes. This retrospective cohort study compared outcomes for operative hip fractures in patients prior to and during the COVID-19 pandemic at a level 1 academic center. Materials and Methods: Data was collected on patients age 18 years or older who underwent operative management for hip fractures performed from January 21, 2019 to July 1, 2019 (pre-pandemic) or from January 21, 2020 to July 1, 2020 (pandemic). COVID-19 status, demographics and outcomes were analyzed. Results: Overall, 159 patients with hip fractures were included in this study, 103 in the 2019 group and 56 in the 2020 group. Within the 2019 group, there was a significantly greater proportion of female patients compared to 2020 ...
Introduction: Methylphenidate (MP) is a widely used psychostimulant prescribed for Attention Defi... more Introduction: Methylphenidate (MP) is a widely used psychostimulant prescribed for Attention Deficit Hyperactivity Disorder, and is also used illicitly by healthy individuals. Chronic exposure to MP has been shown to affect physiology, behavior, and neurochemistry. Methods: The present study examined its effect on the endocannabinoid system. Adolescent rats had daily oral access to either water (control), low dose MP (4/10 mg/kg), or high dose MP (30/60 mg/kg). After 13 weeks of exposure, half of the rats in each group were euthanized, however the remaining rats underwent a four-week long abstinence period. Cannabinoid receptor 1 binding (CB1) was measured with in vitro autoradiography using [3H] SR141716A. Results: Rats who underwent a 4-week abstinence period after exposure to chronic HD MP showed increased binding compared to rats with no abstinence period in several cortical and basal ganglia regions of the brain. In contrast to this, rats who underwent a 4-week abstinence perio...
Purpose To use serial PET/MRI imaging to radiographically evaluate the metabolic activity of the ... more Purpose To use serial PET/MRI imaging to radiographically evaluate the metabolic activity of the ACL graft over the first post-operative year. Methods Six patients undergoing primary ACL reconstruction were recruited in this prospective study in an inpatient university hospital. All patients underwent femoral and tibial suspensory cortical fixation with quadrupled semitendinosus autograft hamstring ACL reconstruction by an orthopaedic surgeon. Simultaneous 18F-FDG PET and MRI of both the operative and non-operative knee was performed at three, six, and 12 months post-operatively. Quantification of the mean standardized uptake value (SUV) within the whole-knee, as well as tibial tunnel, femoral tunnel, and intra-articular graft regions of interest (ROIs). Results PET whole-knee activity was increased at all time-points post-operatively compared to the control, non-operative knee. Activity decreased over time, yet considerable generalized activity remained 1 year post-operatively, wit...
Gout is a form of arthritis characterized by buildup of uric acid in synovial fluid, which causes... more Gout is a form of arthritis characterized by buildup of uric acid in synovial fluid, which causes severe swelling and can harm joints, tendons, and other tissues. It affects approximately 4% of the United States population, or approximately 8.3 million people nationwide and is therefore a topic of epidemiologic consideration due to its prevalence. Gout is typically diagnosed via polarized microscopy of arthroscopically-aspirated synovial fluid, which is a costly, time-consuming, labor-intensive, and technically complex procedure, warranting a simpler and less complex method for diagnosis. Here, we propose and validate a colorimetric method which is based on the ability of uric acid to reduce silver nitrate. We also assessed how the colorimetric change can be accelerated by changing the concentration of silver nitrate or adding different silver catalysts, as well as develop a matrix bed for improved handling and ease of use. When translated to the clinic, this diagnostic method for g...
Scaffold design plays an essential role in tissue engineering of articular cartilage by providing... more Scaffold design plays an essential role in tissue engineering of articular cartilage by providing the appropriate mechanical and biological environment for chondrocytes to proliferate and function. Optimization of scaffold design to generate tissue-engineered cartilage has traditionally been conducted using in-vitro and in-vivo models. Recent advances in computational analysis allow us to significantly decrease the time and cost of scaffold optimization using finite element analysis (FEA). FEA is an in-silico analysis technique that allows for scaffold design optimization by predicting mechanical responses of cells and scaffolds under applied loads. Finite element analyses can potentially mimic the morphology of cartilage using mesh elements (tetrahedral, hexahedral), material properties (elastic, hyperelastic, poroelastic, composite), physiological loads by applying loading conditions (static, dynamic), and constitutive stress–strain equations (linear, porous–elastic, biphasic). Fu...
Background Existing ultrashort echo time magnetic resonance imaging (UTE MRI) methods require pro... more Background Existing ultrashort echo time magnetic resonance imaging (UTE MRI) methods require prohibitively long acquisition times (~ 20–40 min) to quantitatively assess the clinically relevant fast decay T2* component in ligaments and tendons. The purpose of this study was to evaluate the feasibility and clinical translatability of a novel abbreviated quantitative UTE MRI paradigm for monitoring graft remodeling after anterior cruciate ligament (ACL) reconstruction. Methods Eight patients who had Graftlink™ hamstring autograft reconstruction were recruited for this prospective study. A 3D double-echo UTE sequence at 3.0 Tesla was performed at 3- and 6-months post-surgery. An abbreviated UTE MRI paradigm was established based on numerical simulations and in vivo validation from healthy knees. This proposed approach was used to assess the T2* for fast decay component ($$ {T}_{2s}^{\ast } $$ T 2 s ∗ ) and bound water signal fraction (fbw) of ACL graft in regions of interest drawn by a...
Purpose: Although surgical repair of distal biceps tendon rupture improves functional outcomes co... more Purpose: Although surgical repair of distal biceps tendon rupture improves functional outcomes compared with nonsurgical treatments, the choice of operative technique remains a matter of preference. This study retrospectively examined outcomes from a repair technique using a volar distal biceps reinsertion secured with a unicortical intramedullary button in the proximal radial tuberosity to determine its safety and functional outcomes. Methods: A single fellowship-trained shoulder and elbow surgeon treated 27 men, average age 48 years (range, 25e66 years), between 2012 and 2016. Patient-reported outcomes included the Disabilities of the Arm, Shoulder, and Hand and American Shoulder and Elbow Surgeons (ASES) satisfaction scores and the Mayo Elbow Performance Score. Average patient follow-up was 24 months. Results: This series had an overall complication rate of 39.3% (11 of 28): 9 lateral antebrachial cutaneous neuropraxias, one radial sensory nerve irritation, and one superficial infection. No complications of peripheral nerve injury, proximal radioulnar synostosis, or rerupture were observed. Results (mean ± SD) demonstrated low disability (Disabilities of the Arm, Shoulder, and Hand score ¼ 2.9 ± 5.3), high satisfaction (American Shoulder and Elbow Surgeons score ¼ 9.3 ± 1.4), and acceptable performance (Mayo Elbow Performance Score ¼ 97.7 ± 6.3). Subcategory analysis identified a correlation between time to surgery and complications. Disability scores were higher in patients with workers' compensation claims versus private insurance (mean, 11.0 vs 1.1). Conclusions: Further trials are required to compare the results and complication rates of this unicortical intramedullary button procedure with other established methods. Type of study/level of evidence: Therapeutic IV.
The purpose of this study was to determine if a Sawbones Scoliosis Model could be used as a simul... more The purpose of this study was to determine if a Sawbones Scoliosis Model could be used as a simulator to train residents in placing pedicle screws-a complex procedure with a steep learning curve. Surgical simulation, a common tool teaching residents complex procedures in a safe environment, was staged using a Sawbones Scoliosis Model. Ten junior and ten senior residents out of 25 total possible residents (80%) were instructed how to place pedicle screws using the free-hand technique. They were then asked to place them unilaterally from T4 to L4 and were assessed on completion time, accuracy placement accuracy, and overall competency using an objective rating scale. Senior residents had an average time to completion of 38.9 ± 4.7 min vs. junior's 50.1 ± 11.7 min, and a pedicle screw accuracy of 43.6 ± 6.4% vs. junior's 44.4 ± 17.4%. Overall competency scores were similar for both groups; however, senior residents scored higher in the time and motion subdomain. Senior resident...
Journal of orthopaedic surgery and research, Jan 22, 2017
One of the major challenges in orthopedics is to develop implants that overcome current postopera... more One of the major challenges in orthopedics is to develop implants that overcome current postoperative problems such as osteointegration, proper load bearing, and stress shielding. Current implant techniques such as allografts or endoprostheses never reach full bone integration, and the risk of fracture due to stress shielding is a major concern. To overcome this, a novel technique of reverse engineering to create artificial scaffolds was designed and tested. The purpose of the study is to create a new generation of implants that are both biocompatible and biomimetic. 3D-printed scaffolds based on physiological trabecular bone patterning were printed. MC3T3 cells were cultured on these scaffolds in osteogenic media, with and without the addition of Calcitonin Receptor Fragment Peptide (CRFP) in order to assess bone formation on the surfaces of the scaffolds. Integrity of these cell-seeded bone-coated scaffolds was tested for their mechanical strength. The results show that cellular p...
We present a surgical strategy to manage multicolumnar tibial plateau fracture variants by addres... more We present a surgical strategy to manage multicolumnar tibial plateau fracture variants by addressing the predominant posterior fragment employing a Lobenhoffer approach in the prone position followed by supine patient repositioning for anterolateral column access. Multicenter retrospective analysis. Three academic Level 1 trauma centers. Twenty-eight cases (28 patients/28 knees) met inclusion criteria between 2003 and 2014. Patient demographic information was retrospectively reviewed with a mean follow-up time of 16.6 months (range 12-34 months). Postoperative radiographic analysis, physical examination findings, and patient outcome scores from the Knee Injury and Osteoarthritis Outcome Score questionnaire were recorded. The average time to union was 3.6 months (range 3-9 months). Eighty-two percent of patients had satisfactory articular reduction (less than 2 mm articular step off). All patients demonstrated satisfactory coronal (medial proximal tibia angle 87 ± 5 degrees) and sag...
Methylphenidate (MP) is the most prescribed psychostimulant for ADHD patients, with clinically de... more Methylphenidate (MP) is the most prescribed psychostimulant for ADHD patients, with clinically demonstrated detrimental effects on bone quality, potentially leading to early onset osteoporosis and higher fracture risk. The underlying mechanism for the effects of MP on bone remains elusive. This study demonstrates that sex- and dose-dependent effects of MP on bone quality and quantity are mediated by osteoclast activity. Four-week-old male and female rats were treated with low and high dose MP for 13 weeks. Bone quality and quantity were analyzed using microCT, mechanical testing, histomorphometry, and TRAP staining. Male and female rat bone marrow-derived osteoclasts were treated in a dose-dependent manner (0-1000 ng/ml) and osteoclast activity was determined at days 5, 7, and 14 using TRAP staining, as well as a pit formation assay at day 18. Animal studies showed a dose- and a sex-dependent decrease in mechanical integrity in femora and increased TRAP staining in MP-treated rats. ...
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