One out of nine Canadian males would suffer prostate cancer (PC) during his lifetime. Life expectancy of males with PC has increased with modern therapy and 90% live >10 years. However, 20% of PC-affected males would develop incurable metastatic diseases. Bone metastases (BM) are present in ~80% of metastatic PC patients, and are the most severe complication of PC, generating severe pain, fractures, spinal cord compression, and death. Interestingly, PC-BMs are mostly osteoblastic. However, the structure of this newly formed bone and how it relates to pain and fracture are unknown. Due to androgen antagonist treatment, different PC phenotypes develop with differential dependency on androgen receptor (AR) signaling: androgen-dependent (AR+), double negative (AR-) and neuroendocrine. How these phenotypes are related to changes in bone structure has not been studied. Here we show a state-of-the-art structural characterization of PCBM and how PC phenotypes are associated to abnormal bone formation in PCBM.

Cadaveric samples (n=14) obtained from metastases of PC in thoracic or lumbar vertebrae (mean age 74yo) were used to analyze bone structure. We used micro-computed tomography (mCT) to analyze the three-dimensional structure of the bone samples. After imaging, the samples were sectioned and one 3mm thick section was embedded in epoxy-resin, ground and polished. Scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) and quantitative backscattering electron (qBSE) imaging were used to determine mineral morphology and composition. Another section was used for histological analysis of the PC-affected bone. Collagen structure, fibril orientation and extracellular matrix composition were characterized using histochemistry. Additionally, we obtained biopsies of 3 PCBM patients undergoing emergency decompression surgery following vertebral fracture and used them for immunohistological characterization.

By using mCT, we observed three dysmorphic bone patterns: osteolytic pattern with thinned trabecula of otherwise well-organized structures, osteoblastic pattern defined as accumulation of disorganized matrix deposited on pre-existing trabecula, and osteoblastic pattern with minimum residual trabecula and bone space dominated by accumulation of disorganized mineralized matrix. Comparing mCT data with patho/clinical parameters revealed a trend for higher bone density in males with larger PSA increase. Through histological sections, we observed that PC-affected bone, lacks collagen alignment structure, have a higher number of lacunae and increased amount of proteoglycans as decorin.

Immunohistochemistry of biopsies revealed that PC-cells inside bone organize into two manners: i) glandular-like structures where cells maintain their polarization in the expression of prostate markers, ii) diffuse infiltrate that spreads along bone surfaces, with loss of cell polarity. These cells take direct contact with osteoblasts in the surface of trabecula. We define that PCBM are mostly composed by AR+ with some double negative cells. We did not observe neuroendocrine phenotype cells.

PCBMs generate predominantly osteoblastic lesions that are characterized by high lacunar density, lack of collagen organization and elevated proteoglycan content. These structural changes are associated with the infiltration of PC cells that are mostly androgen-dependent but have lost their polarization and contact directly with osteoblasts, perhaps altering their function. These changes could be associated with lower mechanical properties that led to fracture and weakness of the PCBM affected bone.

Introduction

Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was to develop an experimental model which would simulate the clinical revision hip scenario and to determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model.

Purpose: We report the prevalence of vitamin D deficiency and other causes of secondary osteoporosis in a group of typical and atypical fragility fracture patients.

Method: A chart audit of 399 patients (117 males, mean age 64.6, SD 12.8; 282 females, mean age 63.5, SD 14.6) referred from an inner city orthopaedic unit to the Metabolic Bone Disease Clinic (MBDC) over a three-year period was conducted. Fracture locations and etiology: 90 hip (76 fragility), 161 wrist (135 fragility), 8 vertebral (6 fragility), 77 shoulder (62 fragility), 62 other sites (45 fragility), 1 both hip and shoulder (fragility).

Results: Thirty percent of patients (42 males, 78 females) had a total of 149 secondary causes of OP recorded. Secondary causes included medication use (oral steroids, anti-convulsants); rheumatic, gastrointestinal and endocrine conditions (RA, IBD, Graves disease, Type I DM, hyperparathyroidism); hypogonadal states (premature ovarian failure, hypogonadism); genetic conditions (hypophosphatasia); hematological conditions (thalassemia); miscellaneous causes (smoking, renal impairment). A total of 308 patients completed blood work, including 269 patients who had a 25-OH vitamin D measurement: 7 patients were deficient at ≤ 25 nmol/l, 137 were insufficient at 26 to 74 nmol/l, and 125 were sufficient at ≥ 75nmol/l. There were no differences between males and females (p = 0.457), or among fracture locations (p 0.246). Over 75% of blood/urine analyses were within the normal range for: 1,25 vitamin D, ALP, ALT, AST, bilirubin, creatinine, T3, T4, homocysteine, magnesium, phosphorus, platelets, serum calcium, protein, albumin, globulin, TSH, tissue transglutaminase, Vit B12, WBC, 24 hour urine calcium and phosphorus. Between 50 and 74% of the blood/urine analyses were within the normal range for: CRP (n = 30; 30% elevated), ESR (n = 173; 43% elevated), testosterone (n = 53; 25% of men below normal), bioavailable testosterone (n = 52; 40% of men below normal), N- telopeptide (n = 5; 30% of women elevated), RBC folate (n = 12; 33% elevated), 24 hour urine creatinine (n = 51; 27% below normal).

Conclusion: Half of the fracture patients were vitamin D insufficient. A standardized blood test protocol for all fragility fracture patients is in use.

Fracture healing continues to pose challenges for researchers and clinicians in the field of trauma and orthopaedic surgery. The future treatment strategies for fracture healing will most likely focus on the use of biologic and biochemical methods in combination with established fixation and mechanical methods. In this study, heparanase (HPSE), a mammalian endo-glycuronidase that promotes angiogenesis through cleavage of the extra cellular matrix (ECM)-heparan sulphate and mobilization of ECM resident growth factors, was investigated for its osteoblasts-stimulating effect.

Osteoblast cells, originated from osteoporotic and healthy human subjects who underwent total knee replacement, were cultured and exposed to HPSE at a series of final concentrations of 1, 3, and 6μg/mL. The cell density, proliferation, alkaline phosphatase (ALP) production and specific activity, and expression of osteogenic genes were examined.

A marked stimulating effect of HPSE in cell density and proliferation was observed in the osteoblastic cultures from both osteoporotic and healthy subjects. The ALP level and its specific activity, a classical osteoblastic marker, were also increased at the presence of HPSE in a dose-dependant manner. The expression of osteogenic pathway genes, particularly bone morphogenic proteins (BMPs), transcription factors SMDs, vascular endothelial growth factor and tissue inhibitor of metallopeptidase (TIMP) were up- or down-regulated, which correlated with the doses of HPSE.

This study is the first to show that HPSE increases cell proliferation and stimulates differentiation in human osteoblasts suggesting that the potential of HPSE as a new biofactor for the treatment of fractures. Further research on HPSE in co-culture of osteoblasts and osteoclasts is under investigation in our laboratory.

Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was

to develop an experimental model which would simulate the clinical revision hip scenario and

Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections.

Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls.

Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects.

Intramedullary reaming causes elevation in intramedullary pressure (IP) and extravasation of intramedullary contents into the venous blood system. This study was to evaluate the effect of an intramedullary suction system (ISS), recently developed in our laboratory, on the IP and fat extravasation in a sheep model.

Twelve skeletal mature sheep were assigned randomly to 2 experimental groups of 6 sheep: instrumentation and reamed intramedullary nailing without the ISS application and instrumentation and reamed intramedullary nailing with ISS application. During reaming, the IP was recorded at each step of the procedure. Haemo-dynamic parameters were monitored at pre-reaming, 10 min post-reaming, and 50 min post-reaming, including, mean arterial blood pressure (MABP), pulmonary artery pressure (PAP), pulmonary arterial CO2 (Paco2), heart rate (HR), and saturated oxygen (SaO2). Blood and lung tissue samples were collected for the examination of medullary fat intravasations.

Dramatic increases in IP were observed in non-ISS group at the six defined measuring times: before drilling, guide wire, reaming 8 mm (reamer size), 9 mm, reaming 10 mm, and reaming 11 mm. The IP during reaming was significantly lower in ISS group (guide wire, 15 mmHg; 8 mm, 13 mmHg; 9 mm, -1 mmHg; 10 mm, 3 mmHg; 11 mm, 16 mmHg) than in non-ISS group (guide wire, 28, 8 mm, 185 mmHg; 9 mm, 168 mmHg; 10 mm, 146 mmHg; 11 mm, 150 mmHg). These reductions were significant with the P values < 0.05 or 0.01. Paco2, was lower in ISS group than non-ISS group (32 and 40 mmHg, respectively), while SaO2 was higher in ISS group than non-ISS group (99 and 91 mmHg, respectively). Histological data revealed fat emboli in sheep lung tissue in non-ISS group. Total lipids in lung specimen was lower in ISS group (7.6 mg/g tissue) than in non-ISS group (13.6 mg/g, P=0.04).

We demonstrate the ISS in controlling the increase in IP occurring in long bone reaming. The ISS allows real time pressure recording and feedback to the operator. With this feedback, the operating surgeon is able to control the rate of forward reaming to prevent major increases in IP

To investigate differences between the Reamer Irrigator Aspirator and the AO reamer on fat embolism outcome using a porcine model.

All animal procedures were approved and performed in accordance with the Animal Care Committee at St. Michael’s hospital. Following anesthetic administration, the animals were stabilised for thirty minutes. One third of the pig’s blood volume was withdrawn to simulate hemorrhagic shock. Each animal was kept in a state of hypovolemia for an hour before transfusion and resuscitation. Once the animal was stabilised surgical exposure of the distal femur was completed. A 12 mm Reamer Irrigator Aspirator or AO reamer was used depending on which group the animal was assigned to. Blood work was obtained at: baseline, immediately after induction of hypovolemia, one hour post hypovolemia, post stabilization, one minute, five minutes, 1.5 hours and three hours after reaming. The results were analyzed for activation of the coagulation system, platelet and neutrophil activation, and cytokine elevation. ANOVA was the primary tool used to assess statistical significance.

There was no statistical difference between the two reamers with respect to PT, APTT, and fibrinogen. There was a statistical difference in D-dimer at 1.5 and three hours post-reaming, with the RIA showing a lower value. Neither reamer demonstrated any systemic platelet nor neutrophil activation. TNF-alpha spiked immediately post-reaming with the RIA group returning to baseline values and the AO group remaining elevated. There is a spike in IL-1B post reaming in the AO group, however this was not seen in the RIA group. No statistical difference was detected between the two reamers.

All markers for platelet and neutrophil activation and the coagulation cascade were measured at the systemic level. Although there is no statistical difference between the RIA and AO reamer, it is possible that activated cells were removed from the systemic circulation and sequestered as thrombi in the pulmonary microvasculature. This hypothesis may be supported by a drop in platelet count and an increase in D-dimer, with the AO reamer suggesting greater thrombi formation. The trends in IL-1B and TNF-alpha seem to suggest that the RIA abrogates the post-reaming proinflammatory state.

Introduction: Tendon tissue engineering entails the generation of a highly ordered collagen matrix with several organization scales that confer the tendon its mechanical functionality. Endogenous production of proteoglycans account for the typical microscopic organization in bundles of the tendon extracellular matrix, as they prevent lateral fusion of collagen fibril by binding the shaft of the fibres and promoting tip to tip fusion. The approach developed in this study is to rely on this molecular endogenous production and to induce a supramolecular uniaxial alignment of collagen fibres bundles with the help of specially designed scaffolds under continuous fluid shear stress.

Methods: Microchannel chitosan scaffolds were produced by casting 2% chitosan gel on a mould equipped with stainless steel needles array that was imaged by optical coherence tomography with a resolution at ~10microns. From OCT measurements, regularly spaced microchannels with clearly delimited boundaries are obtained inside a microporous core of chitosan. By varying the number and the diameter of needles (from 250 μm (microns)to 500 μm (microns)) different types of microstructure have been produced. Microchannels scaffolds were seeded with primary tenocytes explanted from pig tendons and cultured in static culture, as nonstimulated group, and in a perfusion bioreactor.

Results: There was a general increase in the channels occupation ratio for the group stimulated by perfusion, and inversely proportional to the microchannel diameter. Tenocytes were able to proliferate and to produce collagen extracellular matrix from the inner surface of the microchannel up to the whole channel volume.

Conclusion: The proposed microstructure was appropriate for tendon engineering and its channel structure is adequate for direct OCT monitoring.

Introduction: Achieving durable implant–host bone fixation is the major challenge in uncemented revision hip arthroplasty when significant bone stock deficiencies are encountered. The purpose of this study was 1) to develop an experimental model which would simulate the clinical revision hip scenario and 2) determine the effects of alendronate coating on porous tantalum on gap filling and bone ingrowth in the experimental model.

Methods: Thirty-six porous tantalum plugs were implanted into the distal femur, bilaterally of 18 rabbits for four weeks. There were 3 groups of plugs inserted; control groups of porous tantalum plugs (Ta) with no coating, a 2^nd control group of porous tantalum plugs with micro-porous calcium phosphate coating, (Ta-CaP) and porous tantalum plugs coated with alendronate (Ta-CaP-ALN). Subcutaneous fluorochrome labelling was used to track new bone formation. Bone formation was analysed by backscattered electron microscopy and fluorescence microscopy on undecalcified histological sections.

Results: The relative increase in mean volume of gap filling, bone ingrowth and total bone formation was 124 %, 232 % and 170 % respectively in Ta-CaP-ALN compared with the uncoated porous tantalum (Ta) controls, which was statistically significant. The contact length of new bone formation on porous tantalum implants in Ta-CaP-ALN was increased by 700% (8-fold) on average compared with the uncoated porous tantalum (Ta) controls.

Discussion: Alendronate coated porous tantalum significantly modulated implant bioactivity compared with controls. This study has demonstrated the significant enhancement of bone-implant gap filling and bone ingrowth, which can be achieved by coating porous tantalum with alendronate. It is proposed that, when faced with the clinical problem of revision joint replacement in the face of bone loss, the addition of alendronate as a surface coating would enhance biological fixation of the implant and promote the healing of bone defects.

Purpose: The objective of this study is to investigate the effects of the Reamer-Irrigator-Aspirator (RIA) on fat embolism outcome, as compared to the standard AO reamer, utilizing physiologic parameters as outcome measures.

Methods: All animal procedures were approved by the Animal Care Committee. Fifteen animal experiments were completed. Following anesthesia, each pig was intubated and ventilated. Initial blood samples were analyzed for proper ventilation and acceptable baseline conditions (PaCO2 between 35–40 mm Hg). One third of the pig’s blood volume was withdrawn to simulate hemorrhagic shock. Each animal was kept in a state of hypovolemia for an hour before transfusion and resuscitation. Each pig underwent alternate assignment into either the RIA or AO group. The distal femur was exposed and reamed in a retrograde fashion, followed by cement pressurization with methylmethacrylate. Physiologic measurements included mean arterial pressure (MAP), pulmonary arterial pressure (PAP), partial pressure of arterial oxygen (PaO2), and cardiac output. Upon completion, the animals were euthanized. The data was analyzed using the SPSS statistical program.

Results: One animal in the AO group expired after cement pressurization associated with profound hypotension, pulmonary hypertension and eventual cardiac arrest. There was a statistically significant difference for PaO2 (P = 0.004), cardiac output (P = 0.002), and PAP (P = 0.005) between the AO and RIA groups. That is, by the completion of the experiment the RIA group had higher PaO2, lower PAP, and higher cardiac output measurements as compared to the AO group. There was no statistical significance between the two groups with respect to MAP (P = 0.468).

Conclusions: Using established physiologic parameters, there appears to be a difference between the standard AO reamer and the RIA in terms of fat embolism outcome. The RIA showed a more favorable outcome with respect to PAP, PaO2, and cardiac output. With its simultaneous irrigation and aspiration, the RIA may result in less intramedullary fat displacement into the systemic circulation.