Distal Femoral Metaphysis Research Articles

Osteosarcoma with Pathological Fracture: A Rare Case Report

Introduction: Osteosarcoma is a primary malignant bone tumor originating from stem cells and is characterized by the proliferation of tumor cells that directly form immature bone or bone-like tissue. Osteosarcoma represents only 3% to 5% of all spinal malignancies. The aim of study is to discuss the importance of diagnostic investigation for a relatively rare case of spinal osteosarcoma. Case presentation: A 49 years old female came to the Emergency Unit, with a chief complaint of bilateral weakness of lower extremities for 1 year and worsening in 2 weeks. Upon examination, the initial diagnosis was mistaken for a spinal canal stenosis because metastatic bone disease from previous history of malignant melanoma. Subsequently, a decompression with stabilization fusion and biopsy is performed. Primary osteosarcoma was confirmed from histopathology results. Further chemotherapy is planned referring to confirmed primary osteosarcoma on histopathology. Discussion: Spinal osteosarcoma is very rare. Osteosarcoma occurs most frequently in the appendicular skeleton, especially the distal femur and proximal tibial metaphysis, which account for 90% of all cases. Primary osteosarcomas of the vertebral column are uncommon and occur dominantly in the vertebral body. Biopsy remains the gold standard of care for diagnosis. Conclusion: The performance of MRI and pathologic evaluation with immunohistochemistry is particularly important for the differential diagnosis of soft tissue tumors. Histopathologic analysis also plays an important role in differentiating from metastatic bone disease. An aggressive treatment plan and long-term follow-up are mandatory in managing this case. Keywords: osteosarcoma, spinal osteosarcoma, spinal canal stenosis, malignancy, pathological fracture, rare case.

7581 Periodic Administration of Quercetin and Dasatinib Alleviates Skeletal Fragility in the INS2AKITA Mouse Model of Type 1 Diabetes

Abstract Disclosure: R. Dresner-Pollak: Consulting Fee; Self; Opko Biologics LTD.. Speaker; Self; Medison Pharma. N. Lishinsky: None. I. Gurt: None. J. Stokar: None. V. Temkin: None. P. Shivam: None. G. Zatarah: None. J. Milgram: None. R. Shahar: None. Skeletal fragility is a recognized complication of type 1 diabetes (T1D). The risk of hip and non-vertebral fractures is significantly higher in people living with T1D compared to age- and sex-matched non-diabetic controls and those living with type 2 diabetes (T2D). Hip fracture risk is up to six-fold higher in T1D patients; hip fractures occur 10-15 years earlier and the outcome is poorer compared to non-diabetics. Alterations in bone quality are considered major contributors to T1D-related skeletal fragility. As people with T1D live longer, there is a growing need to discover new therapeutics to reduce fracture risk. TID is associated with accelerated biological aging. Cellular senescence is a fundamental mechanism of aging. Senescent cells stop dividing, are resistant to apoptosis and acquire a distinct phenotype that includes secretome changes termed “senescence-associated secretory phenotype” (SASP). Clearing senescent cells with senolytics is recognized as a promising therapeutic approach for multiple conditions in mice and humans We explored the ability of senolytics dasatinib (D), a tyrosine kinase inhibitor, and quercetin (Q), a flavanol, present in fruit and vegetables, drug combination, to alleviate femur fragility in mice with T1D. Ins2Akita mice show a sexual dimorphic effect of the mutant Ins2 allele causing severe hyperglycemia in males. We treated Ins2Akita male and female mice and C57BL/6 wild type (WT) male mice with D + Q administered once monthly for four months beginning at age 3 months. 3-month-old Ins2Akita male mice had higher blood levels of the SASPs components HMGB1, PAI-1, MMP12, and increased gene expression of p53 and senescence effectors p16, p15 and SASPs Il1b, Mmp3, Mmp9, Mmp13, Serpineb2 at the femur diaphysis and in bone marrow mesenchymal stem cells, respectively compared to age-matched WT male mice. In vitro, exposure to glucose levels equivalent to those observed in blood in Ins2Akita male mice induced cellular senescence in IDG-SW3 osteocyte-like cells including a 4-5-fold increase in gene expression of p16INK4a, p21Cip[1], p53, double percentage of SA-β-gal+ cells and P21 protein level. Ingenuity pathway analysis of differentially expressed proteins revealed enrichment for the senescence pathway (Z=1.213; P=1.11E-05). D+Q administration did not affect bone microarchitecture at the spine (L2), distal femur metaphysis and diaphysis assessed by µCT. D+Q administration significantly increased femur resistance to fracture assessed by the 3-point-bending test by increasing whole femur work-to-fracture, the ultimate parameter of bone resistance to failure, and post-yield displacement, an index of matrix composition, organization, and bone quality in Ins2Akita males. No effect was observed in Ins2Akita females or WT male mice, indicating that the intervention is specific for T1D. Senolyitcs D+Q show promise in improving bone health in T1D. Presentation: 6/1/2024

Aerobic exercise training-induced bone and vascular adaptations in mice lacking adiponectin

Adiponectin regulates lipid and glucose metabolism, and insulin sensitivity in various target organs; however, the effects of adiponectin on bone health remain controversial. Exercise training can enhance bone density, bone microarchitecture, and blood flow. This study aimed to elucidate the role of adiponectin in adaptations of bone microarchitecture and bone vasculature in response to aerobic exercise training.Adult male C57BL/6 wild-type (WT) and homozygous adiponectin knockout (AdipoKO) mice were either treadmill exercise trained or remained sedentary for 8–10 weeks. The trabecular structures of the distal femoral metaphysis, a weight-bearing bone, and the mandible, a non-weight-bearing bone, were examined using microcomputed tomography. The femoral principal nutrient arteries were isolated to assess vasoreactivity (vasodilation and vasoconstriction) and structural remodeling.At the femoral metaphysis, impaired trabecular bone structures, including reduced connectivity density and increased trabecular spacing, were observed in AdipoKO mice compared to WT mice. In addition, nitric oxide-mediated, endothelium-dependent vasodilation was substantially reduced, and wall-to-lumen ratio was significantly increased in the femoral principal nutrient artery of AdipoKO mice. Interestingly, although exercise training-induced enhancements in trabecular connectivity density were observed at the femoral metaphysis of both WT and AdipoKO, increased vasoconstrictor responses were only observed in the femoral principal nutrient artery of WT mice, not in the AdipoKO mice. In mandibular trabecular bone, exercise training increased trabecular bone volume fraction (BV/TV, %) and intersection surface in the mandible of both WT and AdipoKO mice.These findings indicate that adiponectin is crucial for maintaining normal bone microarchitecture and vasculature. Although the absence of adiponectin compromises bone vascular adaptation to exercise training in mice, some exercise training-induced alterations in bone microarchitecture occurred in the absence of adiponectin, suggesting contribution of compensatory mechanisms during exercise training.

8079 PPI Breaks a Leg! An Unusual Case of Atypical Femur Fracture

Abstract Disclosure: M. Sedghian: None. M. Flanagan: None. D. Pinkhasova: None. K. Selk: None. G. Moloney: None. Background: Atypical femur fractures (AFF) occur along the shaft of the femur extending from the subtrochanteric region proximally to the distal femoral metaphysis. These fractures have an increased incidence in patients taking bisphosphonates and denosumab for osteoporosis and develop as stress reactions in the lateral cortex of the femoral shaft (beaking). However, few cases that meet the characteristics of these fractures have occurred in patients who have never used antiresorptive drugs. We present a case with a history of long-term proton pump inhibitor (PPI) use and possible association with AFF. Clinical Case: The patient is a 68-year-old female with a past medical history of hypothyroidism who presented to the emergency department (ED) after an atraumatic femur fracture and consequently ground level fall. The patient reported experiencing a distinctive cracking sound in her femur while leaning over to wash her feet, resulting in a fall that prompted her to seek immediate care in the ED. Upon initial evaluation, radiographic imaging was significant for displaced left mid-femoral diaphyseal fracture and right femur lateral cortex thickening consistent with AFF. Labs were consistent with elevated PTH to 100.7 [18.4-80.1], Vit D2 1,25 (OH)2 <8 pg/mL, Vit D 25OH 34 ng/ml [30-100], and Calcium level of 9.5. Upon further history taking, the patient stated that she has been taking PPIs intermittently for more than 10 years. She denied a history of bisphosphonate and denosumab exposure, non-Hodgkin's lymphoma, rheumatoid arthritis, and COL1A2 variant mutations as main predisposing factors for atypical femur fractures. She had potential steroid exposure for less than a year before hospitalization as she was on "adrenal complex" from her functional medicine provider. The patient underwent open reduction and internal fixation of the left femur with placement of intramedullary nail and prophylactic fixation with placement of intramedullary nail of the right femur as there was radiographic evidence of beaking. Discussion/Conclusion: Several studies suggested a possible association between PPIs and fracture risk, especially hip fractures, but the relationship remains contentious. Overall, PPIs are positively associated with elevated fracture risk in multiple studies. Increased gastrin production and hypochlorhydria are the two main mechanisms that affect bone remodeling, decreasing bone turnover, impairing calcium absorption, and altering homocysteine levels through impairment of folate and vitamin B12 absorption.This case supports a potential association between long-term PPI use and atypical femur fractures. There have been other case reports that also highlight this potential risk of PPI use. This shows the importance of more comprehensive research on this topic as the number of patients on long-term PPIs is growing in outpatient settings. Presentation: 6/2/2024

Increased cancellous bone mass accompanies decreased cortical bone mineral density and higher axial deformation in femurs of leptin-deficient obese mice

IntroductionLeptin is a pleiotropic hormone that regulates food intake and energy homeostasis with enigmatic effects on bone development. It is unclear if leptin promotes or inhibits bone growth. The aim of this study was to characterize the micro-architecture and mechanical competence of femur bones of leptin-deficient mice. Materials and methodsRight femur bones of 15-week old C57BL/6 (n = 9) and leptin-deficient (ob/ob, n = 9) mice were analyzed. Whole bones were scanned using micro-CT and morphometric parameters of the cortex and trabeculae were assessed. Elastic moduli were determined from microindentations in midshaft cross-sections. Mineral densities were determined using quantitative backscatter scanning electron microscopy. 3D models of the distal femur metaphysis, cleared from trabecular bone, were meshed and used for finite element simulations of axial loading to identify straining differences between ob/ob and C57BL/6 controls. ResultsCompared with C57BL/6 controls, ob/ob mice had significantly shorter bones. ob/ob mice showed significantly increased cancellous bone volume and trabecular thickness. qBEI quantified a ∼7% lower mineral density in ob/ob mice in the distal femur metaphysis. Indentation demonstrated a significantly reduced Young's modulus of 12.14 [9.67, 16.56 IQR] GPa for ob/ob mice compared to 23.12 [20.70, 26.57 IQR] GPa in C57BL/6 mice. FEA revealed greater deformation of cortical bone in ob/ob as compared to C57BL/6 mice. ConclusionLeptin deficient ob/ob mice have a softer cortical bone in the distal femur metaphysis but an excessive amount of cancellous bone, possibly as a response to increased deformation of the bones during axial loading. Both FEA and direct X-ray and electron microscopy imaging suggest that the morphology and micro-architecture of ob/ob mice have inferior biomechanical properties suggestive of a reduced mechanical competence.

Bone Fragility in High Fat Diet-induced Obesity is Partially Independent of Type 2 Diabetes in Mice

Obesity and type 2 diabetes (T2D) are risk factors for fragility fractures. It is unknown whether this elevated risk is due to a diet favoring obesity or the diabetes that often occurs with obesity. Therefore, we hypothesized that the fracture resistance of bone is lower in mice fed with a high fat diet (45% kcal; HFD) than in mice that fed on a similar, control diet (10% kcal; LFD), regardless of whether the mice developed overt T2D. Sixteen-week-old, male NON/ShiLtJ mice (resistant to T2D) and age-matched, male NONcNZO10/LtJ (prone to T2D) received a control LFD or HFD for 21 weeks. HFD increased the bodyweight to a greater extent in the ShiLtJ mice compared to the NZO10 mice, while blood glucose levels were significantly higher in NZO10 than in ShiLtJ mice. As such, the glycated hemoglobin A1c (HbA1c) levels exceeded 10% in NZO10 mice, but it remained below 6% in ShiLtJ mice. Diet did not affect HbA1c. HFD lowered trabecular number and bone volume fraction of the distal femur metaphysis (micro-computed tomography or μCT) in both strains. For the femur mid-diaphysis, HFD significantly reduced the yield moment (mechanical testing by three-point bending) in both strains but did not affect cross-sectional bone area, cortical thickness, nor cortical tissue mineral density (μCT). Furthermore, the effect of diet on yield moment was independent of the structural resistance of the femur mid-diaphysis suggesting a negative effect of HFD on characteristics of the bone matrix. However, neither Raman spectroscopy nor assays of advanced glycation end-products identified how HFD affected the matrix. HFD also lowered the resistance of cortical bone to crack growth in only the diabetic NZO10 mice (fracture toughness testing of other femur), while HFD reduced the ultimate force of the L6 vertebra in both strains (compression testing). In conclusion, the HFD-related decrease in bone strength can occur in mice resistant and prone to diabetes indicating that a diet high in fat deleteriously affects bone without necessarily causing hyperglycemia.

Dynamic intramedullary crosspinning technique for the treatment of distal femoral metaphyseal fracture in a free‐ranging jaguarundi (Herpailurus yagouaroundi)

AbstractAn approximately 3‐month‐old female free‐ranging jaguarundi (Herpailurus yagouaroundi) was admitted for evaluation of swelling near the right stifle and inability to use the right hindlimb. Radiographic examination revealed a closed, short oblique fracture of the right distal femoral metaphysis, and the bone cortex appeared thin. Because of the poor body condition, the surgical procedure was performed 6 days after admission. The fracture was stabilised using a dynamic intramedullary crosspinning technique. Two 1.5 mm diameter Kirschner (K) wires were introduced at an approximately 20° angle to the sagittal plane of the femur. Radiographic evaluation 3 months after surgery revealed an open distal physis, fracture healing in the remodelling phase and K‐wires engulfed by the bone, which made removal impossible. At the 6‐month follow‐up, a length discrepancy of 0.8 cm in the right femur compared to the left femur was noted. Despite this complication, the locomotion pattern was considered normal according to visual gait analysis.

Reduced osseointegration in disuse and denervation rat models results from impaired cellular responses to multiscale microstructured titanium surfaces.

Immobilization-induced skeletal unloading results in muscle atrophy and rapid bone loss, thereby increasing the risk of falling and the need for implant therapy in patients with extended bed rest or neuromuscular injuries. Skeletal unloading causes bone loss by altering bone growth and resorption, suggesting that implant performance might be affected. To test this, we focused on early events in implant osseointegration. We used the rat sciatic neurectomy-induced disuse model under two different settings. In Study 1, 16 Sprague Dawley rats (SD) were separated into control, sham operated+cast immobilization, and sciatic neurectomy+casting groups; titanium implants with multiscale microtextured topography and hydrophilic chemistry (modSLA) were inserted in the distal femoral metaphysis. Neurectomy surgeries and casting were performed at the same surgical setting as implant placement; rats were euthanized 4 weeks post-implantation. In Study 2, we established the unloaded condition before implantation. A total of 12 SD rats were divided into control and sciatic+femoral neurectomy groups. A total of 24 days after sciatic and femoral neurectomy surgery, rats received implants. Study 2 rats were euthanized at 4 weeks post-implantation. MicroCT and histomorphometry showed that trabecular bone and osseointegration were reduced when disuse was established before implantation. Osteoblasts isolated from Study 1 sciatic neurectomy tibial bones exhibited impaired differentiation on modSLA culture disks, revealing a possible mechanism responsible for the decreased osseointegration observed in the Study 2 rats. This study addressed the importance of considering the mechanical unloading and muscle function history before implant insertion and suggests that implant performance was reduced due to poor cellular ability to regenerate.

Diet composition influences the effect of high fat diets on bone in growing male mice.

The effect of diet-induced obesity on bone in rodents is variable, with bone mass increases, decreases, and no impact reported. The goal of this study was to evaluate whether the composition of obesogenic diet may influence bone independent of its effect on body weight. As proof-of-principle, we used a mouse model to compare the skeletal effects of a commonly used high fat 'Western' diet and a modified high fat diet. The modified high fat diet included ground English walnut and was isocaloric for macronutrients, but differed in fatty acid composition and contained nutrients (e.g. polyphenols) not present in the standard 'Western' diet. Eight-week-old mice were randomized into 1 of 3 dietary treatments (n=8/group): (1) low fat control diet (LF; 10%kcal fat); (2) high fat 'Western' diet (HF; 46%kcal fat as soybean oil and lard); or (3) modified high fat diet supplemented with ground walnuts (HF+walnut; 46%kcal fat as soybean oil, lard, and walnut) and maintained on their respective diets for 9weeks. Bone response in femur was then evaluated using dual energy x-ray absorptiometry, microcomputed tomography, and histomorphometry. Consumption of both obesogenic diets resulted in increased weight gain but differed in impact on bone and bone marrow adiposity in distal femur metaphysis. Mice consuming the high fat 'Western' diet exhibited a tendency for lower cancellous bone volume fraction and connectivity density, and had lower osteoblast-lined bone perimeter (an index of bone formation) and higher bone marrow adiposity than low fat controls. Mice fed the modified high fat diet did not differ from mice fed control (low fat) diet in cancellous bone microarchitecture, or osteoblast-lined bone perimeter, and exhibited lower bone marrow adiposity compared to mice fed the 'Western' diet. This proof-of-principal study demonstrates that two obesogenic diets, similar in macronutrient distribution and induction of weight gain, can have different effects on cancellous bone in distal femur metaphysis. Because the composition of the diets used to induce obesity in rodents does not recapitulate a common human diet, our finding challenges the translatability of rodent studies evaluating the impact of diet-induced obesity on bone.

HISTOLOGICAL EVALUATION OF REPARATIVE OSTEOGENESIS IN CRITICAL SIZE FEMORAL BONE DEFECTS IN RATS OF DIFFERENT AGES AFTER INTRODUCTION OF ALLOGRAFTS SATURATED WITH BLOOD PLASMA GROWTH FACTORS

The increase in injuries and gunshot wounds because of the war in Ukraine makes it imperative to find methods for optimizing bone regeneration and filling large-size bone defects. Aim. Study morphological features of reparative osteogenesis when critical size femoral bone defects in rats in the early reproductive and mature stages are filled with allografts saturated with blood plasma growth factors (GF). Methods. Defects (3 × 3 mm) were created in the distal femoral metaphysis of 60 white laboratory rats, 3-months-old (n = 30) and 12-months-old (n = 30). The defects were filled with bone allografts saturated with GF in the two experimental groups (AlloG+GF), and unsaturated bone allografts in the two control groups (AlloG). All groups contained 15 rats of each age. At 14, 28 and 90 days after the surgery, 5 rats from each group were sacrificed, and histological analyses were performed. Results. In the AlloGgroups, excessive formation of connective tissue was observed 14 and 28 days after the surgery, most evident in the 3-monthold rats. In the AlloG+GF groups, bone formation was delayed at 14 days independent of age, while at 28 and 90 days, the area of bone trabeculae did not differ from the values in the AlloG groups. Throughout the experiment, decreases in allograft area (almost all of it was replaced by bone after 90 days) and connective tissue (completely absent in 3-month-old rats after 90 days) were observed in both AlloG+GF groups. The area of bone trabeculae increased in the period from 14 to 28 days. Conclusion. Saturating allografts with blood plasma growth factors facilitates an increase in the rate at which allografts are replaced by bone tissue, independent of the recipient’s age. However, excessive formation of connective tissues in the defect 14 and 28 days after the surgery, especiallyin 3-month-old rats, may negatively affect the mechanical properties of the bone, which should be considered in clinical practice.

BONE REGENERATION AFTER IMPLANTATION OF CALCIUM PHOSPHATE CEMENTS BASED ON METASTABLE TRICALCIUM PHOSPHATE (IN VIVO EXPERIMENTAL STUDY)

Calcium phosphatCalcium phosphate cement (CPC) is a material used to fill bone defects. Its advantages include being able to fill irregularly shaped spaces, its similarity to bone tissue, and ease of biodegradation. However, insufficient durability and unpredictable rate of resorption limit CPC use. Objective. Study the dynamics of morphological changes in rat femurs after implanting two types of CPC based on metastable αʹ‒tricalcium phosphate(αʹ‒TCP) into defects in the distal metaphysis. Methods. 42 male white rats were used in the study. In each rat, defects were created in the distal metaphysis of the left femur and filled with one of the two types of CPC. The animals were split into two groups: І (n = 21) — CPC based on αʹ‒TCP powder; ІІ (n = 21) — CPС based on αʹ‒TCP powder reinforced with hydroxyapatite (HA) whiskers (4 % mass). Both varieties of CPC were developed and prepared at the Department of Solid-State Physics at the V. N. Karazin Kharkiv National University (Ukraine). 14, 30, and 60 days after the surgery, the animals were sacrificed, and histological analyses were performed. Results. For both types of CPC, inflammation was not observed in the region around the implant at 14, 30, or at 60 days. Bone tissue formed on the surface of the materials. The stages of bone repair were similar to the known stages of bone repair. As a result of the resorption of the CPC, 60 days after surgery the CPC comprised 26.83 % of the area of the defect in group I and 29.93 % in group II. The rest of the area was composed of lamellar bone. The two groups did not differ significantly in rate of CPC resorption or bone tissue formation. Conclusions. The two types of CPC studied, based on αʹ‒TCP (group I) and αʹ‒TCP reinforced with HA whiskers (group II), are biocompatible, osteoconductive, and osteoinductive. In addition, these materials are biodegradable and, with time, are replaced by bone tissue.

SERPINF1 gene variants causing late-onset progressive deforming osteogenesis imperfecta – A study of 18 patients from India

SERPINF1 gene variants lead to a severe type of osteogenesis imperfecta (OI) attributed to defects in the matrix mineralization. We present 18 patients with SERPINF1 gene variants leading to severe progressive deforming OI, the largest series in the world to date. These patients were normal at birth and had the first fracture between 2 months to 9 years; progression of deformities was seen in 12 adolescents who became nonambulatory. Radiologically, compression fractures with kyphoscoliosis, protrusio acetabuli, and lytic lesions in the metaphysis and pelvis were seen in older children with classical popcorn appearance in the distal femoral metaphysis in three. By exome sequencing and targeted sequencing, we identified ten variants. One was unreported and novel; three other novel variants in this series were reported earlier. The recurrent deletion inframe mutation p.phe277del was found in 5 patients from three families. Alkaline phosphatase was elevated in all children on the first visit. Bone mineral density was low in all patients and showed improvement at two years in seven children on regular pamidronate therapy. For others, the 2 year BMD data were not available. The Z scores for four of the seven children showed worsening at the 2-year follow-up.

Effects of Donepezil on the Musculoskeletal System in Female Rats.

The extension of human life makes it more and more important to prevent and treat diseases of the elderly, including Alzheimer's disease (AD) and osteoporosis. Little is known about the effects of drugs used in the treatment of AD on the musculoskeletal system. The aim of the present study was to investigate the effects of donepezil, an acetylcholinesterase inhibitor, on the musculoskeletal system in rats with normal and reduced estrogen levels. The study was carried out on four groups of mature female rats: non-ovariectomized (NOVX) control rats, NOVX rats treated with donepezil, ovariectomized (OVX) control rats and OVX rats treated with donepezil. Donepezil (1 mg/kg p.o.) was administered for four weeks, starting one week after the ovariectomy. The serum concentrations of CTX-I, osteocalcin and other biochemical parameters, bone mass, density, mineralization, histomorphometric parameters and mechanical properties, and skeletal muscle mass and strength were examined. Estrogen deficiency increased bone resorption and formation and worsened cancellous bone mechanical properties and histomorphometric parameters. In NOVX rats, donepezil decreased bone volume to tissue volume ratio in the distal femoral metaphysis, increased the serum phosphorus concentration and tended to decrease skeletal muscle strength. No significant bone effects of donepezil were observed in OVX rats. The results of the present study indicate slightly unfavorable effects of donepezil on the musculoskeletal system in rats with normal estrogen levels.

Alignment and Fixation in Revision Total Knee Arthroplasty With Press-Fit, Offset, Diaphyseal-Engaging Stem Extensions, and Eccentric Reaming Technique

BackgroundA revision total knee arthroplasty must control limb alignment, often to address the cause of failure. Press-fit stems that engage the diaphysis with cement restricted to the metaphysis constitute one fixation technique. These long stems restrict coronal alignment of the prosthesis and as a result reduce the likelihood of extreme malposition. For the same reasons, long stems can make it difficult to manipulate alignment and achieve a specific coronal alignment angle. Nevertheless, femoral stems with a tight diaphyseal fit may still occupy a small range of varus-valgus positions due to the conical distal femoral metaphysis. Pulling the reamer toward the lateral endosteum increases femoral component coronal alignment toward a valgus direction and pushing the reamer medially increases alignment in a more varus direction. A straight stem, in combination with a medially directed reaming, would result in a femoral component that overhangs medially, but an offset stem can recenter the femoral component and maintain the desired alignment. We hypothesized that diaphyseal fit plus this reaming technique can control limb coronal alignment and provide fixation. MethodsThis was a retrospective clinical and long-leg radiographic study of consecutive revision total knee arthroplasties with minimum 2-year follow-up. Outcomes were correlated with New Zealand Joint Registry data to identify rerevisions of 111 consecutive revision knee arthroplasties, 92 after exclusions, at a minimum 2-year (range, 2 to 10) follow-up. ResultsMean femoral and tibial canal fill exceeded 91% on antero-posterior and lateral radiographs. The mean hip-knee-ankle angle was 179.6o (174.9-184.0) with 80% within ± 3o of neutral. The hip-ankle axis crossed the central Kennedy zone in 76.5% of cases and the other 24.6% crossed the inner medial and inner lateral zones. Tibial components: 99.0% ± 3o. Femoral components: 89.5% within ± 3o. There were 5 knees that failed due to infection, 3 from femoral loosening, and 1 due to recurvatum instability from polio. ConclusionsThis study describes a surgical plan and technique for achieving target coronal alignment with press-fit diaphyseal fixation. It is the only series of revision knee arthroplasties with diaphyseal press-fit stems to report canal fill in 2 planes and coronal alignment on full-length radiographs.

AN EXPERIMENTAL INVESTIGATION OF THE MICROARCHITECTURE AND FRACTURE MECHANICS OF FEMURS OF ZUCKER DIABETIC FATTY (ZDF) RATS USING A SIDEWAYS FALL TEST

This study aims to assess the fracture mechanics of type-2 diabetic (T2D) femoral bone using innovative site-specific tests, whilst also examining the cortical and trabecular bone microarchitecture from various regions using micro-computed tomography (CT) of the femur as the disease progresses.Male [Zucker Diabetic Fatty (ZDF: fa/fa) (T2D) and Zucker Lean (ZL: fa/+) (Control)] rats were euthanized at 12-weeks of age, thereafter, right and left femora were dissected (Right femora: n = 6, per age, per condition; Left femora: n=8-9, per age, per condition). Right femurs were notched in the posterior of the midshaft. Micro-CT was used to scan the proximal femur, notched and unnotched femoral midshaft (cortical) of the right femur and the distal metaphysis (trabecular) of the left femur to investigate microarchitecture and composition. Right femurs were fracture toughness tested to measure the stress intensity factor (Kic) followed by a sideways fall test using a custom-made rig to investigate femoral neck mechanical properties.There was no difference in trabecular and cortical tissue material density (TMD) between T2D and control rats. Cortical thickness was unchanged, but trabeculae were thinner (p<0.01) in T2D rats versus controls. However, T2D rats had a greater number of trabeculae (p<0.05) although trabecular spacing was not different to controls. T2D rats had a higher connectivity distribution (p<0.05) and degree of anisotropy (p<0.05) in comparison to controls. There was no difference in the mechanical properties between strains.At 12-weeks of age, rats are experiencing early-stage T2Ds and the disease impact is currently not very clear. Structural and material properties are unchanged between strains, but the trabecular morphology shows that T2D rats have more trabecular struts present in order to account for the thinner trabeculae.

Small changes in thermoregulation influence cancellous bone turnover balance in distal femur metaphysis in growing female mice

Mice are typically housed at temperatures well below their thermoneutral zone. When individually housed at room temperature (~22 °C) mice experience cold stress which results in cancellous bone loss and has the potential to alter the skeletal response to treatment. It is not clear if there is a threshold temperature for cold stress-induced bone loss. It is also not clear if alternative strategies for attenuating cold stress, such as group housing, influence bone accrual and turnover. This study aimed to determine how small differences in temperature (4 °C) or heat loss (individual versus group housing with nestlets) influence bone in growing female C57BL/6 J mice. Five-week-old mice were randomized by weight to 1 of 4 treatment groups (N = 10/group): 1) baseline, 2) single housed at 22 °C, 3) single housed at 26 °C, or 4) group housed (n = 5/cage) with nestlets at 22 °C. Mice in the baseline group were sacrificed 1 week later, at 6 weeks of age. The other 3 groups of mice were maintained at their respective temperatures and housing conditions for 13 weeks until 18 weeks of age. Compared to baseline, mice single housed at room temperature had increased body weight and femur size, but dramatically decreased cancellous bone volume fraction in distal femur metaphysis. The cancellous bone loss was attenuated but not prevented in mice individually housed at 26 °C or group housed at 22 °C. In conclusion, by impacting thermogenesis or heat loss, modest differences in housing conditions could influence experimental results.

Skeletal phenotypes in secreted frizzled-related protein 4 gene knockout mice mimic skeletal architectural abnormalities in subjects with Pyle’s disease from SFRP4 mutations

Mutations in SFRP4 cause Pyle’s bone disease with wide metaphyses and increased skeletal fragility. The WNT signaling pathway plays important roles in determining skeletal architecture and SFRP4 is a secreted Frizzled decoy receptor that inhibits WNT signaling. Seven cohorts of male and female Sfrp4 gene knockout mice, examined through 2 years of age, had a normal lifespan but showed cortical and trabecular bone phenotypes. Mimicking human Erlenmeyer flask deformities, bone cross-sectional areas were elevated 2-fold in the distal femur and proximal tibia but only 30% in femur and tibia shafts. Reduced cortical bone thickness was observed in the vertebral body, midshaft femur and distal tibia. Elevated trabecular bone mass and numbers were observed in the vertebral body, distal femur metaphysis and proximal tibia metaphysis. Midshaft femurs retained extensive trabecular bone through 2 years of age. Vertebral bodies had increased compressive strength, but femur shafts had reduced bending strength. Trabecular, but not cortical, bone parameters in heterozygous Sfrp4 mice were modestly affected. Ovariectomy resulted in similar declines in both cortical and trabecular bone mass in wild-type and Sfrp4 KO mice. SFRP4 is critical for metaphyseal bone modeling involved in determining bone width. Sfrp4 KO mice show similar skeletal architecture and bone fragility deficits observed in patients with Pyle’s disease with SFRP4 mutations.

Closing wedge distal femoral osteotomy for knee valgus: indications, technique, rehabilitation and outcomes

IntroductionIn cases of symptomatic knee valgum, in which deformity majorly originated in the femoral distal metaphysis, 2 main types of femoral osteotomy have been described: medial closing or lateral opening. We have been doing medial closing wedges with anterior second plane cut for years. The reason being a proven similar surgical accuracy associated to a higher and faster healing rate promoted by a larger contact area between the 2 sides of the osteotomy site. The aim of this article is to describe up-to-date closing wedge distal femoral osteotomy strategies: from indication, to ideal correction, surgical technique and patient recovery. MethodsDistal femoral varus osteotomy is indicated in painful valgus knee in which deformity originated majorly in the femoral distal metaphysis. The planning is digitally performed according to the Miniaci method using digital software to have a postoperative weight bearing line passing through the knee joint at 45% to 50% measured from the medial tibial plateau border (0%) to the lateral tibial plateau border (100%). The procedure is performed through medial closing wedges created with 2 medial to lateral and 1 posterior to anterior cutting planes creating an anterior biplanar cut. ResultsUsing our step-by-step way to perform closing wedge distal femoral osteotomy, we standardized our radiological and clinical outcomes. Knowing some tips and tricks to avoid intraoperative complications will help readers to master this procedure. ConclusionsFollowing simple intraoperative landmark and technical guidance bony deformity can be fully corrected by medial closing wedges using an anterior biplanar cut. Patients will demonstrate optimal clinical outcomes including high rate of return to recreational and professional activities.

CLINICAL FEATURES OF CONNECTIVE TISSUE DYSPLASIA, OSGOOD-SCHLATTER DISEASE AND MULTIPLE CORTICAL DISORDERS IN A CHILD.

The aim: To analyze scientific data on the problems of disorders of bone morphogenesis in children, in particular, non-ossifying fibroma. To analyze modern methods of diagnosis and treatment of this disease in the context of the latest scientific achievements. Materials and methods: The latest data of scientists from the world's leading clinics describing various forms of fibrous skeletal lesions in children of differ¬ent ages were analyzed. We examined a boy with fibrous lesions of the cortical layer of the knee joint bones and a girl with a large fibrous focus of the distal femoral metaphysis, which resulted in a closed pathological bone fracture. Surgical treatment, osteosynthesis, marginal resection of the tumor, bone grafting and histological examination were conducted. Conclusions: Despite numerous studies of this disease, the etiopathogenesis of this disease has not been studied. There are no early symptoms of fibrous bone lesions in children. Diagnosis is possible only when a pathological fracture of the affected bone occurs due to extensive growth of fibrous tissue and a significant decrease in the mechanical strength of the bone. Most cases of recognition of such a disease occur accidentally when performing X-ray examinations for other reasons - bruises, sprains, arthralgias, osteochondropathy, infectious diseases, etc. It is known that boys are more mobile and require more frequent X-ray examinations for limb injuries than girls, so the likelihood of accidental detection of such changes increases significantly. Thus, long-term observations of children with fibrous bone lesions have shown that after 40 years, patients rarely developed malignant tumors - osteogenic sarcoma, fibrosarcoma, malignant fibroma of tubular bones, pelvic bones. There are no early symptoms of fibrous bone lesions in children. Recognition of such a disease occurs by chance when X-ray examinations are performed for other reasons.

Cold stress during room temperature housing alters skeletal response to simulated microgravity (hindlimb unloading) in growing female C57BL6 mice

Laboratory mice are typically housed at temperatures below the thermoneutral zone for the species, resulting in cold stress and premature cancellous bone loss. Furthermore, mice are more dependent upon non-shivering thermogenesis to maintain body temperature during spaceflight, suggesting that microgravity-induced bone loss may be due, in part, to altered thermogenesis. Consequently, we assessed whether housing mice at room temperature modifies the skeletal response to simulated microgravity. This possibility was tested using the hindlimb unloading (HLU) model to mechanically unload femora. Humeri were also assessed as they remain weight bearing during HLU. Six-week-old female C57BL6 (B6) mice were housed at room temperature (22 °C) or near thermoneutral (32 °C) and HLU for 2 weeks. Compared to baseline, HLU resulted in cortical bone loss in femur, but the magnitude of reduction was greater in mice housed at 22 °C. Cancellous osteopenia in distal femur (metaphysis and epiphysis) was noted in HLU mice housed at both temperatures. However, bone loss occurred at 22 °C, whereas the bone deficit at 32 °C was due to failure to accrue bone. HLU resulted in cortical and cancellous bone deficits (compared to baseline) in humeri of mice housed at 22 °C. In contrast, fewer osteopenic changes were detected in mice housed at 32 °C. These findings support the hypothesis that environmental temperature alters the skeletal response to HLU in growing female mice in a bone compartment-specific manner. Taken together, species differences in thermoregulation should be taken into consideration when interpreting the skeletal response to simulated microgravity.