Purpose

Developmental exposure to estrogens has been shown to affect a number of organ systems, including long and short bones. Epigenetic effects of DES exposure have been shown to affect the third generation of progeny. Furthermore, recent studies have shown that environmental exposure to estrogen-like compounds is much higher than originally anticipated. This study aims to discover the effect of in utero exposure to a well-known estrogen agonist, diethylstilbestrol (DES), on lumbar bone, intervertebral disc (IVD), and articular cartilage. Femoral bone was studied to determine the specificity of the effect.

Purpose

Metal-on-metal (MoM) articulations in total hip replacement (THR) have become an attractive option for young, active patients. Short-term reports have demonstrated elevated systemic metal ion levels in the blood and urine. Disseminated concentrations of cobalt and chromium have raised concern regarding cellular toxicity, chromosomal damage and adverse local soft tissue reactions.

Long-term studies are required to support the increased use of MoM bearings in younger patients given their potential deleterious effects. The purpose of the current study was to report the seven to 13 year clinical, radiographic, and metal ion results in patients following MoM THR.

Introduction

Metal-on-metal (MoM) articulations in total hip replacement (THR) have become an attractive option for young, active patients. Short-term reports have demonstrated elevated systemic metal ion levels in the blood and urine. Disseminated concentrations of cobalt and chromium have raised concern regarding cellular toxicity, chromosomal damage and adverse local soft tissue reactions.

Long-term studies are required to support the increased use of MoM bearings in younger patients given their potential deleterious effects. The purpose of the current study was to report the 7–13 year clinical, radiographic, and metal ion results in patients following MoM THR.

Purpose

A major drawback of current cartilage and intervertebral disc (IVD) tissue engineering is that human mesenchymal stem cells (MSCs) from osteoarthritic (OA) patients express high levels of type X collagen. Type X collagen is a marker of late stage chondrocyte hypertrophy, linked with endochondral ossification, which precedes bone formation. However, it has been shown that a novel plasma-polymer, called nitrogen-rich plasma-polymerized ethylene (PPE:N), is able to inhibit type X collagen expression in committed MSCs. The aim of this study was to determine if the decreased expression of type X collagen, induced by the PPE:N surfaces is maintained when MSCs are removed from the surface and transferred to pellet cultures in the presence of serum and growth factor free chondrogenic media.

Purpose

Whilst it is known that oxidative stress can cause early degenerative changes observed in experimental osteoarthritis and that a major drawback of current cartilage and intervertebral disc tissue engineering is that human mesenchymal stem cells (MSCs) from osteoarthritis (OA) patients express type X collagen, a marker of late-stage chondrocyte hypertrophy (associated with endochondral ossification), little is known whether the expression of type X collagen in MSCs from OA patients can be related to oxidative stress or inflammatory reactions that occur during this disease.

Purpose: Several studies have shown elevated levels of metal ions in blood of patients with metal-on-metal (MM) total hip arthroplasty (THA). The outstanding question that remains is the clinical impact of these elevated ion levels. Even though it is well known that exposure to heavy metals such as lead, copper, mercury, nickel, and cadmium) may lead to significant alterations in human sperm morphology and motility, less is known on the effect of Co and Cr on semen parameters. The aim of the present study was to investigate the effect of metal ions on the semen of males of child fathering age with MM hip arthroplasty.

Method: Semen was collected form 10 patients between 41 and 49 years old (mean = 45±6 years) by masturbation after 2–3 days of abstinence. Samples were examined within 1h after ejaculation for morphology, motility, and number of sperm cells following standard criteria from the World Health Organization (WHO). Co and Cr concentrations were measured in both the seminal plasma and in the blood of patients by inductively coupled plasma-mass spectroscopy (ICP-MS). Since spermatozoa membrane polyunsaturated fatty acids are vulnerable to attack by reactive oxygen species (leading to peroxide formation), peroxide concentrations were measured in both the seminal plasma and the blood of patients.

Results: Results showed that the concentration of both Co and Cr ions was significantly lower in the seminal plasma than in the blood of the patients. Results also showed that the levels of peroxides were lower in the seminal plasma than in the blood plasma of these patients. Importantly, the ejaculate volume, the sperm density, the total sperm count, the pH, and the percentage of cells with normal morphology were in the range of the WHO criteria for fertile population and also in the range of reference patients in the city of measurements. However, the viability was a little bit lower than what was observed in a fertile population without prosthesis.

Conclusion: The presence of Co and Cr ions in the blood of males of child fathering age with MM hip arthroplasty raised concerns about the quality of semen in these patients. Results of the present study strongly suggest that the raised of Co and Cr had no significant effect on sperm parameters of young patients with MM prosthesis. The methods used to identify potential normal and fertile semen samples are still contradictory and not exactly defined. Studies showed for example that only total numbers of sperm with progressive mobility are significantly different in the fertile than in sub-fertile men, while others suggested that the fertile population should be defined by sperm concentration or sperm morphology. In conclusion, results suggest that Co and Cr ions generated from MM prosthesis have no significant effect on the sperm parameters of young patients of child fathering age. Further longitudinal studies are however necessary to conclusively determine the effect of metal ions from MM prosthesis on sperm parameters.

Purpose: Several studies have been directed toward using mesenchymal stem cells (MSCs) from osteoarthritic (OA) patients for cartilage or disc repair because these patients are the ones that will require a source of autologous stem cells if biological repair of tissue lesions is to be a therapeutic option. A major drawback of current cartilage and intervertebral disc tissue engineering repair is that these cells rapidly express type X collagen, a marker of late stage chondrocyte hyperthrophy implicated in endochondral ossification. However, a novel plasma-polymerized thin film material, named nitrogen-rich plasma-polymerized ethylene (PPE:N), is able to inhibit type X collagen expression in committed MSCs. The specific aim of this study was to determine if the suppression of type X collagen by PPE:N is maintained when MSCs are transferred to pellet cultures in chondrogenic defined media.

Method: MSCs were obtained from aspirates from the intramedullary canal of donors undergoing total hip replacement for OA using a protocol approved by the Research Ethics Committee of our institution. Cells were then expanded for 2–3 passages in DMEM high glucose supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 μg/ml streptomycin, and finally cultured on polystyrene (PS) cell culture dishes or PPE: N surfaces for 3 and 7 days. Cells were transferred for 3 additional days in a chondrogenic serum free media (DMEM high glucose supplemented with 2 mM L-glutamine, 20 mM HEPES, 45 mM NaHCO3, 100 U/ml penicillin, 100 μg/ml streptomycin, 1 mg/ml bovine serum albumin, 5 μg/ml insulin, 50 μg/ml ascorbic acid, 5 ng/ ml sodium selenite, 5 μg/ml transferrin) in pellet culture or on PS cell culture dishes. Cells were then lysed and proteins were separated on 4–20% acrylamide gels and transferred to nitrocellulose membranes. Type X collagen was detected by Western blot; GAPDH expression was used as an internal control for protein loading.

Results: Results showed that type X collagen protein was expressed in MSCs from OA patients cultured on polystyrene but was suppressed when cultured on PPE: N. Since defined chondrogenic medium are commonly used in pellet culture to promote in vitro chondrogenesis, we then investigated the effect of transferring cells pre-cultured on PPE:N into pellet culture on type X collagen expression. However, the decreased type X collagen expression was not maintained in these conditions and that the expression returned to control values. The decreased type X collagen expression was maintained when the cells were cultured on PS cell culture dishes.

Conclusion: The use of MSCs is promising for tissue engineering of cartilage and intervertebral disc. The present study confirmed the potential of PPE:N surfaces in suppressing type X collagen expression in MSCs from OA patients. However, when MSCs stem cells are transferred to pellet cultures, type X collagen is rapidly re-expressed suggesting that pellet cultures may not be suitable for chondrogenesis of MSCs from OA patients.

Purpose: Mesenchymal stem cells (MSCs) from osteoarthritic (OA) patients are not well characterized and little is known of how they are regulated. Recent evidence indicates that a major drawback of current cartilage and intervertebral disc (IVD) tissue engineering is that human MSCs from OA patients express type X collagen (COL10), a marker of late-stage chondrocyte hypertrophy (associated with endochondral ossification). However, the intracellular pathways for transducing signals that regulate hypertrophy in MSCs remain unclear. In chondrocytes, this pathway is mediated by mitogen activated protein kinase (MAPK) p38. The aim of this study was to determine the phosphorylation levels of ERK/p38 MAPK signaling molecules in MSCs from OA patients compared to those from normal patients.

Method: MSCs were obtained from aspirates from the intramedullary canal of donors (60–80 years of age) undergoing total hip replacement for OA. Cells were cultured in DMEM high glucose supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 μg/ml streptomycin for 2–3 passages. Cells were then lysed and proteins were separated on 10% acrylamide gels and transferred to nitrocellulose membranes. Protein expression was determined by Western blot using specific antibodies directed against type X collagen, ERK, phosphorylated-ERK, p38, phosphorylated-p38, JNK, phosphorylated-JNK, AKT, and phosphorylated-AKT. GAPDH was used as a housekeeping gene. Proteins were detected using the West Pico Chemiluminescence substrates and analyzed using the Bio-Rad VersaDoc equipped with a cooled CCD 12 bit camera. Normal mesenchymal stem cells from a 22 years old woman were purchased from Lonza (Switzerland).

Results: Results show that the expression of COL10 was markedly increased in MSCs of OA patients compared to control patient. Results also shows that the phosphorylation of all the signal transduction proteins studied was induced in MSCs of patients with OA. Indeed, the phosphorylation of ERK (3.4±0.9 times the control), p38 (1.7±0.3 times the control), JNK (5.40±1.14 times the control), and AKT (4.3±0.8 times the control) was higher in MSCs of OA patients compared to control normal patients.

Conclusion: In the normal donor, MSCs continue to exhibit their in situ behavior in that they expressed very little or no COL10. This may relate to the fact that normal MSCs being multipotent in nature like to maintain an undifferentiated state. In contrast, MSCs from OA patients expressed COL10: this suggests that they are in a situation were they can be preprogrammed not only to replace the degraded articular cartilage but also the damaged subchondral bone. Since the phosphorylation of ERK/p38 MAPK signaling molecules is also lower in normal MSCs, our results also suggest that this signaling pathway is implicated in the control of COL10 expression. This finding is of great importance for the understanding of COL10 regulation in general and may lead to important advances in the comprehension of COL10 related diseases.

Purpose: A major drawback of current cartilage and intervertebral disc tissue engineering is that human mesenchymal stem cells (MSCs) from osteoarthritis (OA) patients express type X collagen (COL10), a marker of late-stage chondrocyte hypertrophy (associated with endochondral ossification). Parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) regulate endochondral ossification by inhibiting chondrocyte differentiation toward hypertrophy. In the present study, we investigated the effect of PTH on the expression of COL10 in MSCs from OA patients and analyzed the potential mechanisms related to its effect.

Method: MSCs were obtained from aspirates from the intramedullary canal of donors (60–80 years of age) undergoing total hip replacement for OA. Cells were cultured for 2–3 passages in DMEM high glucose supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 μg/ml streptomycin. Cells were then incubated for 0–24h without (Control) or with 100 nM PTH (1–34). Cells were lysed and proteins were separated on 10% acrylamide gels and transferred to nitrocellulose membranes. Protein expression was detected by Western blot using specific antibodies directed against COL10, p38, phosphorylated-p38 (p-p38), SAP/JNK, phosphorylated-SAP/JNK (p-JUNK). GAPDH was used as a housekeeping gene. Protein levels were analyzed using a Bio-Rad VersaDoc equipped with a cooled CCD 12 bit camera.

Results: Results showed that PTH inhibited in a time-dependent manner the expression of COL10 in MSCs from OA patients. The level of expression reached 21% of control (79% inhibition) after 24h. This inhibitory effect of PTH was reversed by Calphostin C, an inhibitor of protein kinase C. To further investigate the mechanism of action related to the effect of PTH on COL10 expression, we measured the phosphorylation of p38 and showed that PTH also inhibited this phosphorylation, which is an indicator of its activity. The level of phosphorylation reached 74% of control after 3h and stayed stable thereafter. Similarly, treatment of MSCs with PTH suppressed the phosphorylation of JNK, another major stress-activated MAP kinase. The level of phosphorylation reached 65% of control after 6h and returned to control values after 24h.

Conclusion: Results of the present study suggested that PTH may be a potential regulator of COL10 expression in MSCs from OA patients. Results also suggested a role for the protein kinase C and the p38/JNK pathways in this regulation. p38 and JNK are serine and threonine protein kinases that are activated by osmotic pressure, stress, and cytokines. It is therefore not surprising that their activities were elevated as OA (degenerative joint disease) is a result of trauma or infection to the joint and is characterized by an up-regulation of cytokines. Further studies are however necessary to better understand the role of these molecules in hypertrophy.

Purpose: Several studies have shown elevated levels of metal ions in blood of patients with metal-on-metal (MM) total hip arthroplasty (THA). To minimize wear, the elastohydrodynamic theory suggests wear reduction for larger diameter head bearings. This significant reduction in wear has been demonstrated in hip simulators for the 36 mm-head compared to the 28 mm-head prosthesis. However, the survival of larger head MM THAs and the levels of metal ions in the blood of patients having these implants are still to be determined.

Method: Fifty (50) patients (56 hips) who received a DePuy Ultamet™ MM hip bearing (40/44 mm-head) at our Institution between July 1st 2007 and August 31st 2008 were included in the study. Clinical and radiologic data were collected pre-operatively as well as at 6–8 weeks, 4–6 months, and 1 year postoperatively. Results were compared to those of subjects (65 patients, 71 hips) who received a 36 mm-head prosthesis. Cobalt (Co) and chromium (Cr) concentrations were measured at 1 year post-operatively in the blood of patients by ICP-MS. Since Co and Cr ions have the potential to induce irreversible biochemical damage to macromolecules, the levels of oxidative stress markers (total antioxidants and lipid peroxides) were measured in the plasma of these patients.

Results: At their 1-year post-operatively follow-ups, all patients were doing well and no sign of osteolysis was observed on X-rays. Harris Hip Score increased in both groups with a tendency to higher score in the 40–44 mm group compared to the 36 mm group. Activity score also increased in both groups after 1 year without statistical significant differences. Results also show that the levels of Co and Cr ions increased significantly in both groups compared to the Pre-OP control group. The levels of Co were also significantly higher in patients with large head arthroplasty (40 and 44 mm-head) compared to those of the 36 mm-head group (p=0.012). The levels of Cr were similar in both the large head and the 36 mm-head group (p=0.41). Finally, results show that there were no differences in the levels of total antioxidants and peroxides between the 40–44 mm group and the 36 mm group. Moreover, there was no increase in the level of these markers of oxidative stress compared to the Pre-OP control group.

Conclusion: The present study shows that at 1-year postoperatively, patients with large 40–44 mm-head THA had comparable clinical outcomes than those with 36 mm-head prosthesis. However, the levels of Co ions were significantly higher in these patients compared to patients with 36 mm-head THA. This suggests a higher health risk for these patients due to the presence of these ions. However, there were no effects on the levels of oxidative stress markers in the blood of these patients, suggesting that there is no increased risk at short-term. In conclusion, due to the high level of Co ions, longer follow-ups are required to conclusively determine the outcomes of the patients and the survivorship of these new bearings.

Purpose: The presence of metal ions in the blood of patients with a metal-on-metal (MM) bearing points to the importance of understanding the long-term effects of these ions. Metal ions have the potential to induce the production of reactive oxygen species (ROS), making them prime suspects for inducing molecular damage in circulating cells. The aim of this study was to analyze the levels of oxidative stress markers in the plasma of patients with hip surface replacement.

Method: Blood was collected up to 3 years after implantation from 66 patients with articular surface replacement (ASRÔ, DePuy Orthopaedics) and 54 patients with 36 mm-head MM THA. Forty (40) pre-operative patients were also assessed as control group. Total anti-oxidant levels were measured by the Oxford Biomedical total antioxidant power assay (Oxford, MI) to obtain an overview of the defense capacity of patient’s oxidative stress. Peroxide concentrations were measured by the Biomedica OxyStat assay (Medicorp, Montreal, QC) to quantify damage to lipids in the systemic circulation. Nitrototyrosine levels were quantified using the BIOXYTECH® Nitrotyrosine-EIA assay (OxisResearch™, Portland OR) to measure damage to proteins. The concentrations of metal ions were analyzed by inductively coupled plasma-mass spectroscopy.

Results: Results showed that there were no statistical differences in the concentrations of total antioxidants, lipid peroxides, and protein nitrotyrosines between the control, the ASR, and the 36 mm-head groups. Furthermore, there was no correlation between the concentrations of these markers and the concentrations of both Co and Cr ions (r2 £ 0.006).

Conclusion: The single most significant obstacle preventing a broader application of metal-on-metal hip arthroplasties and resurfacings continues to be the concerns regarding elevated metal ion levels in the blood and urine of patients. The present results showed that there were no changes in the levels of oxidative stress markers in patients with MM bearings compared to the control group. Given the possible latency periods related to metal ion exposure, longer follow-ups are required to conclusively determine the effects of elevated circulating ions on oxidative stress in the blood of patients with MM bearings.

Purpose: Recent evidence indicates that a major drawback of current cartilage and intervertebral disc (IVD) tissue engineering is that human mesenchymal stem cells (MSCs) from osteoarthritic patients rapidly express type X collagen (COL10A1), a marker of late-stage chondrocyte hypertrophy associated with endochondral ossification. We recently discovered that a novel atmospheric-pressure plasma-polymerized thin film substrate, named “nitrogen-rich plasma-polymerized ethylene” (PPE:N), is able to inhibit COL10A1 expression in committed MSCs. However, the cellular mechanisms implicated in the inhibition of COL10A1 expression by PPE:N surfaces are unknown.

Method: Human mesenchymal stem cells (MSCs) were obtained from aspirates from the intramedullary canal of donors (60–80 years of age) undergoing total hip replacement for osteoarthritis. Bone marrow aspirates were processed and MSCs were cultured on commercial polystyrene (PS control) and on PPE:N surfaces in the presence of different kinases and cyclooxygenase inhibitors for 3 days. Total RNA was extracted with TRIzol reagent (Invitrogen, Burlington, ON) and the expression of COL10A1, cyclooxygenase-1 (COX-1), and 5-lipoxygenase (5-LOX) genes was measured by real-time quantitative RT-PCR.

Results: Results showed that a non-specific inhibitor of cyclooxygenases reduced the expression of COL10A1. In contrast, inhibitors of protein kinases stimulated the expression of COL10A1. Furthermore, potent and selective inhibitors of COX-1 and 5-LOX also reduced the expression of COL10A1. However, COX-2 and 12-LOX inhibitors had no significant effect on the expression of COL10A1. COX-1 gene expression was also decreased when MSCs were incubated on “S5” PPE:N surfaces. Interestingly, MSCs did not express 5-LOX.

Conclusion: PPE:N surfaces suppress COL10A1 expression through the inhibition of COX-1 which is directly implicated in the synthesis of prostaglandins. The decreased expression of COX-1 and COL10A1 in human MSCs cultured on PPE:N is therefore in agreement with the induction of the osteogenic capacity of rat bone marrow and bone formation by systemic or local injection of PGE2 in rats. However, PGE2 and other prostaglandins inhibited COL10A1 expression in chick growth plate chondrocytes. This suggests that the effect of prostaglandins on COL10A1 expression may be cell-specific or may be dependent on pre-existing patho-physiological conditions.

Introduction: Several studies have shown the presence of cobalt (Co) and chromium (Cr) ions in blood, urine, and organs of patients after THA using Co-Cr alloy-based implants. Even though it is well known that exposure to heavy metals may lead to significant alterations in human sperm morphology and motility, less is known on the effect of Co and Cr on semen parameters after metal on metal (MOM) hip replacement.

Methods: Semen was collected form 10 patients between 41 and 49 years old (mean=45.9±3.0 years) by masturbation after 2–3 days of abstinence. The time of implantation varied from 1 to 9 years (mean=5.1±3.9 years). Samples were collected in a sterile container and examined within 1h after ejaculation for morphology, motility, and number of sperm cells following standard criteria. All patients were doing well at their follow-up visits (Harris Hip Score=94±4; UCLA activity a score=7±1) and no sign of osteolysis was observed on X-rays.

Co and Cr concentrations were measured in both the seminal plasma and in the blood of patients by inductively coupled plasma-mass spectroscopy (ICP-MS).

Results: results showed that the levels of Co in the seminal plasma and the blood of the patients were not statistically different. However, the level of Cr was significantly lower in the seminal plasma than in the blood of the patients. The ejaculate volume (2.1 ±0.6 ml), the sperm density (66±53 x 106), the total sperm count (151±75 x 106/ml), the pH (8), and the percentage of normal morphology (46±18%) were in the range of the WHO criteria for fertile population and also in the range of reference patients in the city of measurements. However, the viability was lower than that observed in a fertile population without prosthesis (41±19%).

Conclusions: results of the present study strongly suggest that both Co and Cr ions crossover to the semen but that their concentrations were too low to significantly affect sperm parameters of young patients with MM prosthesis. Further longitudinal studies are however necessary to conclusively determine the effect of metal ions from MM prosthesis on sperm parameters.

Introduction: Metal on metal hip implants continue to be successful alternatives to conventional bearings in younger patients with osteoarthritis. Levels of metal ions such as cobalt (Co) and chromium (Cr) increase in patients with metal bearing hip replacements and resurfacings. These particles are cytotoxic, induce bone loss, and lead to malignant tumors in rats. A subset of these patients are considered outliers as they have unusually high levels of Co and Cr ions. Given the increasing prevalence of metal bearings and the potential for cellular toxicity, we attempted to determine whether patient or surgical factors could account for abnormally elevated ion levels.

Methods: We analyzed the Co and Cr levels from whole blood in 661 patients with metal on metal hip bearings. Patient outliers were defined as those who had ion levels ≥ three-fold the mean value. Twenty-four patients (3.6%) had abnormally high metal ion levels, which included 15 patients that underwent total hip replacements and 9 patients following hip resurfacings. These patients were followed prospectively with the Harris Hip Score (HHS) and the University of California Los Angeles (UCLA) activity score. Serial radiographs and ion levels were analyzed at regular intervals. Oxidative stress markers (total anti-oxidants, peroxide, and nitro-tyrosine) were also measured from whole blood to determine if these correlated with an increase ion levels in outlier patients.

Results: Post-operative HHS and UCLA activity scores improved significantly compared to pre-operative values. There was no statistical correlation between outlier ion levels, patient demographics, HHS and UCLA activity scores. Radiologic parameters such as cup inclination and femoral component neck-shaft angle could not account for higher ion levels in these outliers. Oxidative stress markers were similar to the levels observed in the control patients with normal ion values following with metal on metal hip implants.

Conclusion: We could not identify any patient or surgical factors that could explain the abnormally high metal ion levels in the outlier patients. This suggests that the cause of ion level increase is multifactorial. The clinical relevance of such high levels of ions remains unknown given that there was no increase in serum oxidative stress markers. Further studies are necessary to better understand the effect of abnormal elevations in metal ions given the recent concerns of pseudotumours following metal on metal hip implants.

Aim: To determine the MRI findings in patients with persistent painful metal on metal (MOM) hip arthroplasty and compare the results with a control group of patients with MOM or metal on polyethylene THA without symptoms.

Methods: 20 patients with normal inflammatory markers and normal plain radiographic imaging that had undergone primary THA were enrolled to this study. Patients were chosen to be included in 4 groups;

Patients having metal-on-polyethylene THA or resurfacing without pain (Control group),

Operated hips were evaluated with MRI by one musculoskeletal radiologist who was blinded to the radiographic findings and clinical symptoms. All images were assessed for the presence of a juxtaarticular or periprosthetic abnormalities, including fluid collections, soft tissue masses, osseous abnormalities, and patterns of contrast enhancement of lesions.

Results: 5 patients were included in each group. All patients had undergone their THA at least 1 year prior to the MRI examination (mean 18 months). MRI findings including muscle atrophies, joint effusions, stress fractures, bone marrow oedema and muscle avulsions were equally distributed in all groups.

Conclusions: MOM THA or high metal ion levels had no specific MRI findings to explain the hip pain in these groups of patients.

Purpose: Metal-on-metal articulations in total hip arthroplasty (THA) have been recently re-introduced for the treatment of osteoarthritis. There have been excellent short-term clinical outcomes reported. The long-term clinical results of these implants are still unknown. In this study, we examined the four to ten -year results of metal-on-metal total hip arthroplasty at our institution.

Method: All patients receiving a metal-on-metal prosthesis were prospectively registered in a computerized database. The period July 1997 – May 2003 was selected for analysis. This group contained 251 cases (207 patients) and had an average follow-up of 6.8 years. Of the 251 implants the femoral head components were either Metasul^™ (203) or Ultamet^™ (48) and the acetubular component Fitek^™ (12), Interop^™ (191) or Pinnacle^™ (48). All patients were assessed with the Harris hip and UCLA activity scores at routinely scheduled follow-up visits. The mean age of patients at surgery was 52 years (18 to 70 years old). The average follow-up was of 6.8 years (4.2–10 years). No patients were lost to follow-up.

Results: The mean UCLA and Harris hip score pre-operatively were 3.6 (1–8) and 42 (15–81), respectively. Values of the UCLA and the Harris hip scores on the most recent follow-up visit were 7.0 (60% of patients had a score equal to or greater than 7) and 85 (70% of patients had a score equal to or greater than 85), respectively. Thirteen hips (5.1%) were revised in total: 1 (0.4%) for early deep infection, 1 (0.4%) for revision of undersized stem and 11 (4.3%) for acetabular revisions due to manufacturing defects. Radiological results showed no osteolysis and 9 non-progressive radiolucency.

Conclusion: At four to ten year follow-up, metal-on-metal total hip replacement provides consistently good clinical and radiographic results with a low revision rate. They provide longstanding pain alleviation and improved function and activity levels in patients suffering from osteoarthritis.

Purpose: Several studies have shown elevated levels of metal ions in the blood of patients with metal-on-metal (MM) total hip arthroplasty (THA). Even though there is no conclusive evidence that the elevated levels of ions have any detrimental effects on the patients, the presence of these ions is still a cause of concerns. The potential of metal ions released from MM implants for oxidative stress is unknown. In the present study, we measured the concentrations of oxidative stress markers in the plasma of patients with MM THAs.

Method: Blood from patients having MM THAs was collected up to 10 years post-operatively into Sarstedt Li-Heparin tubes. Plasma was prepared by centrifugation at 500 × g for 10 min. Plasma was chosen as opposed to whole blood because it is known that the assays for oxidative stress are not recommended for blood and can lead to erroneous data. Total antioxidant levels were measured by the Oxford Biomedical total antioxidant power assay to obtain an overview of the defense capacity of patients against oxidative stress. The activity of catalase and glutathione peroxidase, two antioxidant enzymes acting on specific reactive oxygen species, was measured by enzymatic assays. Peroxide concentrations were measured by the Biomedica Oxy-Stat assay to quantify damage to lipids in the systemic circulation. Nitrototyrosine levels were quantified using the BIOXYTECH® Nitrotyrosine-EIA assay to measure damage to proteins. Levels in patients without prostheses were used as control.

Results: There were no statistical differences in the concentrations of total antioxidants, lipid peroxides, and nitrotyrosines throughout the period of study. The activity of catalase and glutathione peroxidase was also stable over time. Moreover, there was no correlation between the concentrations of these markers and the concentrations of both cobalt and chromium ions.

Conclusion: Metal ions have the potential to induce the production of reactive oxygen species (free radicals) and cause oxidative stress in the plasma of patients with MM THAs. The present study showed that there were no changes in the levels of oxidative stress markers or antioxidant enzymes in these patients up to 10 years post-operatively. Taken together, the data strongly suggest that metal ions may not cause a significant oxidative stress in patients with MM THAs.

Hip surface replacement is an alternative for young patients considered for hip replacement. The in vivo release of ions from these surfaces has yet to be well evaluated. In the present study, we compared the concentrations of metal ions in blood of patients with hip surface replacement and metal-on-metal (MM) total hip arthroplasty (THA).

Blood was collected six months and one year after implantation time into Sarstedt Monovette® tubes for trace metal analysis from patients having Articular Surface Replacement (ASR®, DePuy Orthopaedics; n=61), 28 mm-head MM THA (n=18), and 36 mm-head MM THA (n=25). The concentrations of cobalt (Co), chromium (Cr), and molybdenum (Mo) were analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS). Since metal ions are potent inducers of oxidative stress, total antioxidant, peroxide, and nitrotyrosine levels (oxidative stress markers) were also measured in plasma of the patients.

The median Co and Cr levels progressively and significantly increased in the three groups during the first year post-operation (compared to patients without hip bearings (n=25)). After six months, the levels of Co and Cr were significantly higher in patients with ASR and 28 mm MM THA than in patients with 36 mm MM THA. There was no difference after one year. The level of activity, as measured by the UCLA activity score, was higher in ASR patients than in 28 and 36 mm MM THA after one year. No differences were observed for Mo levels in these patients when compared to our control group. There was no increase of oxidative stress marker levels in patients with ASR and 36 mm MM THA and no correlation between the concentrations of Co and Cr ions and the levels of oxidative stress markers.

Our results show that, at one year post-operation, the concentration of ions in patients with ASRs is similar than those in patients with MM THAs. Moreover, results suggest that metal ions liberated from MM bearings do not induce damage to macromolecules by oxidative stress in plasma of patients. Longer follow-ups are still required to characterise the concentration of ions in ASR and to determine conclusively the effects of elevated circulating ions.

Although the etiology of low back pain is unclear, it is believed that intervertebral disc (IVD) degeneration plays a major role. In the present study, we sought to determine if bovine IVD cells maintain their phenotype in a mouse subcutaneous injection model, while embedded or not in biocompatible matrices.

Nucleus pulposus (NP) cells were isolated from adult bovine tails. Ten million cells were resuspended either in 500 ƒÝl of DMEM or in a negatively (alginate) or positively (chitosan) charged matrix. The mixtures were then injected subcutaneously in Balc/c nude mice. After two weeks, the mice were sacrificed and the implants harvested. The implants were examined histologically with a hematoxylin and eosin stain. The implant size was measured and the cells were counted. Proteoglycan was assessed by the GAG assay. The expression of type I and II collagens, aggrecan, and CD24 genes was analyzed by reverse transcription ¡V polymerase chain reaction (RT-PCR).

Histologic evaluation confirms the presence of cells in all NP implants. The presence of alginate increased the implant size, the number of cells in the implants, and to a lesser extent, the proteoglycan content, compared to implants formed with cells injected alone. However, chitosan had no effect on the implant size, the number of cells and the aggrecan content. NP implants expressed the same pattern of genes as the native NP tissue (i.e. type I and II collagens, aggrecan, and CD24). The presence of alginate did not affect this expression pattern whereas chitosan decreased slightly their expression.

After injection in mice, bovine NP cells appeared to retain their native phenotype. The RT-PCR analysis revealed that NP cells expressed aggrecan, type I and type II collagens as well as CD24, a specific marker for the NP phenotype. Also, NP cells can be embedded in matrices to produce NP-like features in vivo. In conclusion, we have developed a simple mouse subcutaneous injection model that recreates the features of the native IVD and avoids the need to use a disc degeneration model.

The aim of this study was to analyze in human macrophages the effects of Co²⁺ and Cr³⁺ ions on the activity of caspase-8 and caspase-3, initiator and executioner of apoptosis, respectively. Caspase-3 and -8 activities were measured by colorimetric assays. Results show that Co²⁺ ions induced caspase-3 activity in a time-dependent manner. Co²⁺ had no effect on caspase-8 activity. The activation of caspase-3 by Cr³⁺ was time-dependent while caspase-8 activity reached a maximum after eight hours and decreased thereafter. Since caspase-8 is primarily activated by membrane-associated events, our results suggest that Cr³⁺ interacts with cell membrane components to induce macrophage apoptosis, whereas Co²⁺ seems to stimulate apoptosis most likely through intracellularly located mechanisms.

Because of their potential for improved wear performance, there has been a revived interest in metal-metal bearings, made of cobalt-chromium-molybdenum alloys, as an alternative to the use of conventional metal-polyethylene bearings. However, metal ion toxicity remains a major cause for concern. Previous studies suggested that both cobalt (Co²⁺) and chromium (Cr³⁺) ions induce macrophage apoptosis. The interest in apoptosis lies in the fact that it offers specific targets for therapeutic intervention.

The aim of this study was to analyze the effects in human macrophages of Co²⁺ and Cr³⁺ ions on the activity of caspase-8 and caspase-3, initiator and executioner of apoptosis, respectively.

U937 human macrophages were exposed to 0–10 ppm Co²⁺ (CoCl₂) and 0–500 ppm Cr³⁺ (CrCl₃). Caspase-3 and caspase-8 activities were measured by colorimetric assays based on the recognition of specific amino acid sequences (DEVD and IETD, respectively).

Results show that Co²⁺ ions induced caspase-3 activity with a significant increase after four hour incubation and a maximal 2.65-fold increase reached after twenty-four hour with 10 ppm. Co²⁺ had no effect on caspase-8 activity.

Cr³⁺ ions significantly stimulated caspase-3 activity after four hours with a maximal 1.75-fold stimulation reached after twenty-four hours, reaching only 50% of that observed with Co²⁺. Caspase-8 activity was significantly increased after two hours incubation, peaking at eight hours with a 2.2-fold increase, and decreasing thereafter.

Since caspase-8 is primarily activated by membrane-associated events, our results suggest that Cr³⁺ interacts with cell membrane components to induce macrophage apoptosis. On the other hand, Co²⁺ seems to stimulate caspase-3 activity and apoptosis most likely through intracellularly located mechanisms.