Sports and osteoarthritis

Knee osteoarthritis in the former elite football players and the ordinary population: a comparative cross-sectional study

A cross-sectional case-control study compared subjective knee function, quality of life and radiographic knee osteoarthritis (OA) between 45 former elite football players and an age-matched general male population. Participants completed the Knee OA Outcome Score (KOOS), a quality-of-life assessment (EQ-5D-3 L) and standing knee radiographs. Among the players, 24 (53%) sustained at least one moderate or severe knee injury, while 21 (47%) did not recall any injury. Players with previous knee injuries reported significantly lower knee-specific and general quality-of-life scores (KOOS 69; EQ-5D-3 L 0.69 (0.2)) compared to the non-injured players (KOOS 92; EQ-5D-3 L 0.81 (0.2)) or the control population (KOOS 90; EQ-5D-3 L 0.83 (0.2)). The injured knees had higher radiographic OA Kellgren-Lawrence (KL) scale grades 1.7 (1.3) than the knees of the non-injured players 0.8 (1.0) or the control knees 0.8 (1.0)Former elite football players who had previously sustained a moderate or severe knee injury reported inferior knee function and lower quality of life. Injured knees had higher levels of radiographic OA. Non-injured players reported similar knee and general function and their knees had similar grades of OA to those in the control group. The defining moment for long-term knee preservation in football should be injury prevention protocols.

Association of Knee Osteoarthritis and Flexion Contracture With Localized Tibial Articular Cartilage Loss: Data From the Osteoarthritis Initiative

OBJECTIVE

To evaluate whether a knee flexion contracture (FC) was associated with localized tibial articular cartilage loss over a 1-year period using Osteoarthritis Initiative quantitative data.

METHODS

Five hundred seventy-eight participants from a previously established nested case-control study of people with radiographic knee OA with or without progression, based on radiographs and symptoms, had their knee range of extension measured at baseline and received magnetic resonance imaging (MRI) at baseline and 1 year. The tibial articular cartilage of the medial and lateral condyles was segmented into anterior, center, and posterior regions. We tested for associations between knee FC (defined as lack of extension to 0°), and localized changes in tibial articular cartilage thickness or percent of denuded bone (0 mm thickness) after 1 year relative to baseline using ANOVA, controlling for baseline MRI outcomes and clinical factors.

RESULTS

Knee FC was associated with denuded bone in the medial condyle center (β 0.44, 95% CI 0.02-0.86) and preserved cartilage thickness in the medial condyle posterior (β 0.01, 95% CI 0.002-0.03) regions.

CONCLUSION

Knee FC unloading the tibial center region and loading the posterior region was associated with localized articular cartilage loss centrally and preserved articular cartilage posteriorly. These findings are consistent with knee FC negatively affecting unloaded tibial articular cartilage.

The Coronal Alignment of Lower Limbs in the Adolescent Football and Ice Hockey Players

Background

To investigate the influence of sport-specific activities on coronal axial alignment of the lower limbs in adolescent football and ice hockey players.

Methods

This cross-sectional study targeted healthy adolescent male football and ice hockey players with at least 3 years of sports participation. 90 football and 38 ice hockey players aged 12-16 years were divided into five age-matched subgroups. Coronal alignment of the lower limbs was determined by measuring the players' intercondylar or intermalleolar (ICD-IMD) distance with a custom-made calliper. In addition, their sports history was recorded. An age-matched comparison between the two sports groups was performed using the two-way model ANOVA and a multiple regression model for ICD-IMD was constructed. Results were additionally compared with age-matched data from the general population published in recent literature.

Results

A statistically significant increase in ICD-IMD values (p < 0.05) was found between 12 (football 0 mm; ice hockey - 64 mm) and 16 years (football 340 mm; ice hockey 310 mm) in both sports groups. Results of regression analysis of pooled group data showed that ICD-IMD has low positive correlation (r = 0.407; r2 = 0.168; p < 0.05) with time of participation in sport, but no association with age of athletes at the start of their sport participation (r = - 0.018; r2 = 0.000; p > 0.05). There were no statistically significant differences between the two groups at any time point. Both sports groups showed a significant increase in ICD-IMD values (mean 198 mm) after the age of 14 compared to the general population.

Conclusions

Participation in football and ice hockey is associated with a similar increase in ICD-IMD in the adolescent years in male athletes. The observed increase was higher in both groups of athletes than in their peers who do not regularly participate in sports.

Level of Evidence

Level 4 (case series).

J-shaped association of dietary catechins intake with the prevalence of osteoarthritis and moderating effect of physical activity: an American population-based cohort study

Background

Catechins are a class of natural compounds with a variety of health benefits, The relationship between catechins and the prevalence of osteoarthritis (OA) is unknown. This study investigated the associations between daily intake of catechins and the prevalence of OA among American adults and assessed the moderating effect of physical activity (PA).

Methods

This study included 10,039 participants from the National Health and Nutrition Examination Survey (2007-2010,2017-2018). The logistic regression, weighted quantile sum (WQS) regression, and restricted cubic spline (RCS) regression models were conducted to explore the associations between daily intake of catechins and the prevalence of OA. Moreover, interaction tests were performed to assess the moderating effect of PA.

Results

After multivariable adjustment, the weighted multivariable logistic regression and RCS regression analyses revealed significant J-shaped non-linear correlations between intakes of epigallocatechin and epigallocatechin 3-gallate had significant associations with the prevalence of OA among in U.S. adults. WQS regression analysis showed that excessive epigallocatechin intake was the most significant risk factor for OA among all subtypes of catechins. In the interaction assay, PA showed a significant moderating effect in the relationship between epigallocatechin intake and OA prevalence.

Conclusions

The intake of gallocatechin and gallocatechin 3-gallate had a significant negative correlation with the prevalence of OA and the dose-response relationship was J-shaped.PA below 150 MET-min/week and the threshold intakes of 32.70mg/d for epigallocatechin and 76.24mg/d for epigallocatechin 3-gallate might be the targets for interventions to reduce the risk of developing OA.

Arthralgia in female Masters weightlifters

BACKGROUND

Arthralgia or joint pain is a heterogeneous condition including organic and nonorganic joint pain. It is common in older populations, particularly in females. There is evidence that menopausal changes are associated with increased prevalence of arthralgia. While physical activities have been recommended to mitigate osteoarthritis (OA) and arthralgia, sport participation also carries risk factors due to excessive loading of some joints and possible injuries. The aim was to evaluate the association of training patterns, prior injuries, and severity of menopausal symptoms with arthralgia in female Masters weightlifters.

METHODS

Competitive female Masters weightlifters (n=868, 30-78 years) from 30 countries completed an online survey including joint pain for different anatomical sites, weightlifting training and performance, sport history, and menopausal symptoms. Logistic regression models were used to estimate the association of training patterns, prior sport participation, and menopausal symptom severity with arthralgia separately for shoulders, spine, hips, knees, ankles, elbows, and hands.

RESULTS

Arthralgia was most reported in knees (38.8%), shoulders (29.8%), hands/wrists (28.8%), and hips (24.9%). The prevalence of arthralgia was 51.5% in pre-menopausal women, 62.4% in women post natural menopause and 73.3% in women post medical or surgical menopause. Lifting heavier weights was associated with arthralgia in hips (OR=1.05, p=0.03), knees (OR=1.06, p=0.01), and hands/wrists (OR=1.05, p=0.04), but prior strength training was protective for arthralgia in the shoulders (OR=0.66, p=0.02). Prior injuries and psychological menopausal symptom severity were associated with an increased risk for arthralgia (p<0.01).

CONCLUSIONS

Arthralgia was common in competitive female weightlifters. Training frequency was not associated with arthralgia, but lifting heavier weights relative to age and body mass was. Prior injuries and menopausal symptoms were associated with arthralgia, but prior strength training was protective of arthralgia in the shoulders. Athletes, coaches and sports medicine professionals should be aware that prevalence of polyarthralgia increases in post-menopausal athletes.

Shoulder structure and function: The impact of osteoarthritis and rehabilitation strategies

STUDY DESIGN

Invited review.

BACKGROUND

Shoulder osteoarthritis can result in significant functional deficits. To improve diagnosis and treatment, we must better understand the impact of osteoarthritis on shoulder biomechanics and the known mechanical benefits of currently available treatments.

PURPOSE

The purpose of this paper is to present up-to-date data on the effects of osteoarthritis and rehabilitation on the biomechanical parameters contributing to shoulder function. With this goal, we also reviewed the anatomy and the ranges of motion of the shoulder.

METHODS

A search of electronic databases was conducted. All study designs were included to inform this qualitative, narrative literature review.

RESULTS

This review describes the biomechanics of the shoulder, the impact of osteoarthritis on shoulder function, and the treatment of shoulder osteoarthritis with an emphasis on rehabilitation.

CONCLUSIONS

The shoulder is important for the completion of activities of daily living, and osteoarthritis of the shoulder can significantly reduce shoulder motion and arm function. Although shoulder rehabilitation is an integral treatment modality to improve pain and function in shoulder osteoarthritis, few high-quality studies have investigated the effects and benefits of shoulder physical and occupational therapies. To advance the fields of therapy and rehabilitation, future studies investigating the effects of therapy intensity, therapy duration, and the relative benefits of therapy subtypes on shoulder biomechanics and function are necessary.

Health challenges and acute sports injuries restrict weightlifting training of older athletes

Objectives

To quantify acute injuries sustained during weightlifting that result in training restrictions and identify potential risk factors or preventative factors in Master athletes and to evaluate potentially complex interactions of age, sex, health-related and training-related predictors of injuries with machine learning (ML) algorithms.

Methods

A total of 976 Masters weightlifters from Australia, Canada, Europe and the USA, ages 35–88 (51.1% women), completed an online survey that included questions on weightlifting injuries, chronic diseases, sport history and training practices. Ensembles of ML algorithms were used to identify factors associated with acute weightlifting injuries and performance of the prediction models was evaluated. In addition, a subgroup of variables selected by six experts were entered into a logistic regression model to estimate the likelihood of an injury.

Results

The accuracy of ML models predicting injuries ranged from 0.727 to 0.876 for back, hips, knees and wrists, but were less accurate (0.644) for shoulder injuries. Male Master athletes had a higher prevalence of weightlifting injuries than female Master athletes, ranging from 12% to 42%. Chronic inflammation or osteoarthritis were common among both men and women. This was associated with an increase in acute injuries.

Conclusions

Training-specific variables, such as choices of training programmes or nutrition programmes, may aid in preventing acute injuries. ML models can identify potential risk factors or preventative measures for sport injuries.

Knee osteoarthritis in young growing rats is associated with widespread osteopenia and impaired bone mineralization

Osteoarthritis (OA) leads to joint pain from intraarticular inflammation with articular cartilage erosion, deterioration of joint function and abnormal subchondral bone structure. Besides aging, chronic repetitive joint injury is a common risk factor in young individuals. Nevertheless, whether OA is associated with bone loss at other skeletal sites is unclear. Since OA-associated proinflammatory cytokines-some of which are osteoclastogenic factors-are often detected in the circulation, we hypothesized that the injury-induced knee OA could result in widespread osteopenia at bone sites distant to the injured knee. Here we performed anterior cruciate ligament transection (ACLT) to induce knee OA in one limb of female Sprague-Dawley rats and determined bone changes post-OA induction by micro-computed tomography and computer-assisted bone histomorphometry. We found that although OA modestly altered bone density, histomorphometric analyses revealed increases in bone resorption and osteoid production with impaired mineralization. The bone formation rate was also reduced in OA rats. In conclusions, ACLT in young growing rats induced microstructural defects in the trabecular portion of weight-bearing (tibia) and non-weight-bearing bones (L5 vertebra), in part by enhancing bone resorption and suppressing bone formation. This finding supports the increasing concern regarding the repetitive sport-related ACL injuries and the consequent bone loss.

The results of meniscal allograft transplantation surgery: what is success?

BACKGROUND

Meniscal allograft transplantation (MAT) may improve symptoms and function, and may limit premature knee degeneration in patients with symptomatic meniscal loss. The aim of this retrospective study was to examine patient outcomes after MAT and to explore the different potential definitions of 'success' and 'failure'.

METHODS

Sixty patients who underwent MAT between 2008 and 2014, aged 18-50 were identified. Six validated outcome measures for knee pathologies, patient satisfaction and return to sport were incorporated into a questionnaire. Surgical failure (removal of most/all the graft, revision MAT or conversion to arthroplasty), clinical failure (Lysholm < 65), complication rates (surgical failure plus repeat arthroscopy for secondary allograft tears) and whether patients would have the procedure again were recorded. Statistics analysis included descriptive statistics, with patient-reported outcome measures reported as median and range. A binomial logistic regression was performed to assess factors contributing to failure.

RESULTS

Forty-three patients (72%) responded, mean age 35.6 (±7.5). 72% required concomitant procedures, and 44% had Outerbridge III or IV chondral damage. The complication rate was 21% (9). At mean follow-up of 3.4 (±1.6) years, 9% (4) were surgical failures and 21% (9) were clinical failures. Half of those patients considered a failure stated they would undergo MAT again. In the 74% (32) reporting they would undergo MAT again, median KOOS, IKDC and Lysholm scores were 82.1, 62.1 and 88, compared to 62.2, 48.5 and 64 in patients who said they would not. None of the risk factors significantly contributed to surgical or clinical failure, although female gender and number of concomitant procedures were nearly significant. Following MAT, 40% were dissatisfied with type/level of sport achieved, but only 14% would not consider MAT again.

CONCLUSIONS

None of the risk factors examined were linked to surgical or clinical failure. Whilst less favourable outcomes are seen with Outerbridge Grade IV, these patients should not be excluded from potential MAT. Inability to return to sport is not associated with failure since 73% of these patients would undergo MAT again. The disparity between 'clinical failure' and 'surgical failure' outcomes means these terms may need re-defining using a specific/bespoke MAT scoring system.

Radiographic analysis of lower limb alignment in professional football players

INTRODUCTION

To radiographically analyze lower limb alignment in adult asymptomatic professional football players and to correlate these values to clinical measurements.

MATERIALS AND METHODS

Twenty-four asymptomatic players [24.2 (3.6) years] were enrolled. Standard bilateral lower limb anteroposterior weight-bearing radiographs were acquired and clinical measurement of intercondylar/intermalleolar (ICD/IMD) distance was performed. Coronal plane mechanical alignment was assessed by five angles: leg mechanical axis (LMA), lateral proximal femoral angle (LPFA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and lateral distal tibial angle (LDTA). Their values were compared to the reference values for adult population. An inter-individual comparison between right/left and dominant/non-dominant leg was added. The sum of bilateral LMA was correlated against ICD/IMD and against ICD/IMD adjusted for body height.

RESULTS

Football players presented with ICD/IMD of 46.5 (19.8) mm. Two, out of five, lower leg coronal angles showed significant differences (p < 0.001) compared to reference data from literature: LMA 5.8 (3.0)º vs.1.2 (2.2)º and MPTA 83.5 (2.6)º vs. 87.2 (1.5)º. No significant differences between left/right leg and dominant/non-dominant leg were established. Summed up bilateral LMA showed a high correlation to IMD/ICD (r = 0.8395; R² = 0.7048), and even higher to ICD/IMD adjusted for body height (r = 0.8543; R² = 0.7298).

CONCLUSIONS

This study was radiographically confirming increased varus of elite football players toward general population. Apex of the varus deformity was located in the proximal tibia. Clinical measurement of ICD/IMD adjusted for body height highly correlated with the radiographic values of coronal alignment; therefore, it may be used in population studies.

Difference in Articular Degeneration Depending on the Type of Sport

Objective  To determine whether type-II collagen degradation is determined by the type of sport. Carboxy-terminal telepoptide of type-II collagen (CTX-II), a serum biomarker of collagen degradation, was measured in athletes who play different sports, and was compared with matched controls.

Methods  The sample size consisted of 70 female participants aged between 18 and 25 years, 15 of whom were members of a soccer team, 10 of a futsal (a variant of association football played on a hard court) team, 10 of a handball team, 18 of a volleyball team, and 7 of a swimming team. A total of 9 age- and sex-matched individuals with sedentary lifestyles were included in the control group. 3-mL blood samples were collected from each participant, and they were analyzed using an enzyme-linked immunosorbent assay (ELISA).

Results  A comparison of the CTX-II concentrations of the players of different sports with those of the control group resulted in the following p -values: volleyball ( p  = 0.21); soccer ( p  = 0.91); handball ( p  = 0.13); futsal ( p  = 0.02); and swimming ( p  = 0.0015). Therefore, in the investigated population, futsal represented the highest risk for type-II collagen degradation and, consequently, for articular cartilage degradation, whereas swimming was a protective factor for the articular cartilage. No statistically significant difference was found in the body mass index among the groups.

Conclusion   Futsal players are exposed to greater articular degradation, while swimmers exhibited less cartilage degradation compared with the control group in the study population, suggesting that strengthening the periarticular muscles and aerobic exercise in low-load environments has a positive effect on the articular cartilage.

The Effects of a Physically Active Lifestyle on the Health of Former Professional Football Players

The purpose of this investigation was to determine if a physically active lifestyle affects the health of former football players. Sixty former professional football players aged 40⁻50 years and who ended their sports career at least ten years ago were recruited for the study and grouped into two groups based on their physical activity habits after their retirement. Health and lifestyle characteristics were collected through a questionnaire to obtain information about recreational physical activity levels, diseases, family medical history, smoking, alcohol intake and dietary habits. Furthermore, lung functions, blood parameters and cardiovascular health were evaluated. Our results showed that body weight and body fat percentage were significantly higher in retired footballers who had a sedentary lifestyle compared to those who were physically active. The absolute and predicted values for forced expiratory volume in one-second values were higher in the active group. Twelve retired athletes were found to have intraventricular conduction delay. The findings suggest that former footballers who have higher levels of physical activity have advanced body composition, respiratory functions and serum lipids compared to former footballers with less active lifestyles. It is recommended that former elite athletes should maintain physically active lifestyles to sustain their health and reduce the risk of disease and disability in the later years of life.

Articular cartilage and sternal fibrocartilage respond differently to extended microgravity

The effects of spaceflight on cartilaginous structure are largely unknown. To address this deficiency, articular cartilage (AC) and sternal cartilage (SC) from mice exposed to 30 days of microgravity on the BION-M1 craft were investigated for pathological changes. The flight AC showed some evidence of degradation at the tissue level with loss of proteoglycan staining and a reduction in mRNA expression of mechano-responsive and structural cartilage matrix proteins compared to non-flight controls. These data suggest that degradative changes are underway in the AC extracellular matrix exposed to microgravity. In contrast, there was no evidence of cartilage breakdown in SC flight samples and the gene expression profile was distinct from that of AC with a reduction in metalloproteinase gene transcription. Since the two cartilages respond differently to microgravity we propose that each is tuned to the biomechanical environments in which they are normally maintained. That is, the differences between magnitude of normal terrestrial loading and the unloading of microgravity dictates the tissue response. Weight-bearing articular cartilage, but not minimally loaded sternal fibrocartilage, is negatively affected by the unloading of microgravity. We speculate that the maintenance of physiological loading on AC during spaceflight will minimize AC damage.

The influences of walking, running and stair activity on knee articular cartilage: Quantitative MRI using T1 rho and T2 mapping

OBJECTIVE

To explore the different influences of walking, running and stair activity on knee articular cartilage with T1 rho and T2 mapping sequences.

MATERIALS AND METHODS

MRI (3.0-T) scans of the right knee were performed in twenty-three young healthy adults immediately after 30 minutes of rest, walking, running and stair activity respectively. Articular cartilage was quantitatively assessed based on T1 rho and T2 relaxation times. Analysis of variance for random block design data, bonferroni test and paired samples t tests were performed to estimate the different influences of physiological activities on articular cartilage.

RESULTS

T1 rho and T2 values had reductions after physiological activities in all regions of articular cartilage. T1 rho and T2 values were decreased more after running than walking. T1 rho and T2 values were decreased more after stair activity than running, except for femoral cartilage. The superficial layer of patella cartilage had higher reduction rates than the deep layer. The T1 rho and T2 values of articular cartilage were reduced in the following order: patellofemoral cartilage> medial tibiofemoral cartilage> lateral tibiofemoral cartilage. Patellofemoral cartilage experienced reductions in the following order: lateral part> middle part> medial part. Tibiofemoral cartilage had reductions in the following order: posterior part> middle part> anterior part.

CONCLUSIONS

T1 rho and T2 mapping sequences can quantitatively reflect the different influences of physiological activities on knee articular cartilage. Fluid shifts, collagen fiber deformation, spatial heterogeneity, inherent differences in material properties and tissue stiffness have close relationship with cartilage loading characteristics.

The Competitive Senior Athlete

Clinicians should discuss common health issues of the older population and how medical problems affect their sports performance. Patients with chronic conditions, such as hypertension and diabetes mellitus, benefit from participation in sports. However, special care should be taken to keep the patient healthy and minimize effects of these conditions and their treatments in athletic performance. Another important consideration in the older athlete is fluid ingestion and the increased risk of dehydration. There is evidence that physical exercise reduces pain in osteoarthritis and enhances physical function of affected joints. Older athletes often use multiple medications and dietary supplements; Clinicians should educate patients about possible effects of medications in sports performance.

Genipin crosslinking decreases the mechanical wear and biochemical degradation of impacted cartilage in vitro

High energy trauma to cartilage causes surface fissures and microstructural damage, but the degree to which this damage renders the tissue more susceptible to wear and contributes to the progression of post-traumatic osteoarthritis (PTOA) is unknown. Additionally, no treatments are currently available to strengthen cartilage after joint trauma and to protect the tissue from subsequent degradation and wear. The purposes of this study were to investigate the role of mechanical damage in the degradation and wear of cartilage, to evaluate the effects of impact and subsequent genipin crosslinking on the changes in the viscoelastic parameters of articular cartilage, and to test the hypothesis that genipin crosslinking is an effective treatment to enhance the resistance to biochemical degradation and mechanical wear. Results demonstrate that cartilage stiffness decreases after impact loading, likely due to the formation of fissures and microarchitectural damage, and is partially or fully restored by crosslinking. The wear resistance of impacted articular cartilage was diminished compared to undamaged cartilage, suggesting that mechanical damage that is directly induced by the impact may contribute to the progression of PTOA. However, the decrease in wear resistance was completely reversed by the crosslinking treatments. Additionally, the crosslinking treatments improved the resistance to collagenase digestion at the impact-damaged articular surface. These results highlight the potential therapeutic value of collagen crosslinking via genipin in the prevention of cartilage degeneration after traumatic injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:558-565, 2017.

Development and Prevention of Running-Related Osteoarthritis

Studies investigating the effect of running on risk for developing osteoarthritis at weight-bearing joints have reported with conflicting results. Generally, moderate-level running is not likely detrimental to joint health. However, many factors may be associated with the increased risk of developing osteoarthritis in runners. Factors often implicated in the development of osteoarthritis comprise those that increase joint vulnerability and those which increase joint loading. It is therefore suggested that running has different effects on different people. Efforts should be made to identify those with joint vulnerability and joint loading, and measures should be taken to have those factors and/or their running programs modified to run safely. Further investigations are needed to examine the effect of running on joint health under different conditions to confirm the association between exposure to risk factors and development of osteoarthritis, as well as to validate the effectiveness of measures for preventing running-related osteoarthritis.

Injurious Loading of Articular Cartilage Compromises Chondrocyte Respiratory Function

OBJECTIVE

To determine whether repeatedly overloading healthy cartilage disrupts mitochondrial function in a manner similar to that associated with osteoarthritis (OA) pathogenesis.

METHODS

We exposed normal articular cartilage on bovine osteochondral explants to 1 day or 7 consecutive days of cyclic axial compression (0.25 MPa or 1.0 MPa at 0.5 Hz for 3 hours) and evaluated the effects on chondrocyte viability, ATP concentration, reactive oxygen species (ROS) production, indicators of oxidative stress, respiration, and mitochondrial membrane potential.

RESULTS

Neither 0.25 MPa nor 1.0 MPa of cyclic compression caused extensive chondrocyte death, macroscopic tissue damage, or overt changes in stress-strain behavior. After 1 day of loading, differences in respiratory activities between the 0.25 MPa and 1.0 MPa groups were minimal; however, after 7 days of loading, respiratory activity and ATP levels were suppressed in the 1.0 MPa group relative to the 0.25 MPa group, an effect prevented by pretreatment with 10 mM N-acetylcysteine. These changes were accompanied by increased proton leakage and decreased mitochondrial membrane potential, as well as by increased ROS formation, as indicated by dihydroethidium staining and glutathione oxidation.

CONCLUSION

Repeated overloading leads to chondrocyte oxidant-dependent mitochondrial dysfunction. This mitochondrial dysfunction may contribute to destabilization of cartilage during various stages of OA in distinct ways by disrupting chondrocyte anabolic responses to mechanical stimuli.

Abnormal expression of key genes and proteins in the canonical Wnt/β-catenin pathway of articular cartilage in a rat model of exercise-induced osteoarthritis

To investigate the molecular pathogenesis of the canonical Wnt/β-catenin pathway in exercise-induced osteoarthritis (OA), 30 male healthy Sprague Dawley rats were divided into three groups (control, normal exercise‑induced OA and injured exercise‑induced OA groups) in order to establish the exercise‑induced OA rat model. The mRNA and protein expression levels of Runx‑2, BMP‑2, Ctnnb1, Sox‑9, collagen Ⅱ, Mmp‑13, Wnt‑3a and β‑catenin in chondrocytes were detected by reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemical staining. The mRNA levels of Runx‑2, BMP‑2 and Ctnnb1 were upregulated in the normal exercise‑induced OA and injured exercise‑induced OA groups; while Runx‑2 and BMP‑2 were upregulated in the injured exercise‑induced OA group when compared with the normal exercise‑induced OA group. The protein levels of Mmp‑13, Wnt‑3a and β‑catenin were increased and collagen Ⅱ was reduced in the normal exercise‑induced OA and injured exercise‑induced OA groups. Ctnnb1, Wnt‑3a and β‑catenin, which are key genes and proteins in the canonical Wnt/β‑catenin pathway, were abnormally expressed in chondrocytes of the exercise‑induced OA rat model. Ctnnb1, β‑catenin and Wnt‑3a were suggested to participate in the pathogenesis of exercise‑induced OA by abnormally activating the Wnt/β‑catenin pathway during physical exercise due to excessive pressure. The results of the present study may provide an improved understanding of the pathogenesis of exercise-induced OA.

The Effect of Risk Factors on the Levels of Chemical Elements in the Tibial Plateau of Patients with Osteoarthritis following Knee Surgery

The aim of this study was to evaluate the aforementioned chemical elements in tibial plateau samples obtained during knee arthroplasty. The gender-specific analysis of chemical element levels in the bone samples revealed that there were statistically significant differences in the concentration of Pb and Se/Pb ratio. The contents of elements in the tibial plateau in the patients with osteoarthritis (OA) can be arranged in the following descending order: F(-) > K > Zn > Fe > Sr > Pb > Mn > Se > Cd > THg. We observed statistical significant effects of environmental factors including smoking, seafood diet, and geographical distribution on the levels of the elements in tibial bone. Significant positive correlation coefficients were found for the relationships K-Cd, Zn-Sr, Zn-F(-), THg-Pb, Pb-Cd, Se-Se/Pb, Se-Se/Cd, Se/Pb-Se/Cd, Pb-Cd/Ca, Cd-Cd/Ca, and F(-)-F(-)/Ca·1000. Significant negative correlations were found for the relationships THg-Se/Pb, Pb-Se/Pb, Cd-Se/Pb, K-Se/Cd, Pb-Se/Cd, Cd-Se/Cd, THg-Se/THg, Pb-Se/THg, Se-Pb/Cd, Zn-Cd/Ca, and Se/Cd-Cd/Ca. The results reported here may provide a basis for establishing reference values for the tibial plateau in patients with OA who had undergone knee replacement surgery. The concentrations of elements in the bone with OA were determined by age, presence of implants, smoking, fish and seafood diet, and sport activity.

Why Do Osteochondral Allografts Survive? Comparative Analysis of Cartilage Biochemical Properties Unveils a Molecular Basis for Durability

BACKGROUND

Transplantation of osteochondral allografts (OCAs) freshly preserved for ≥30 days has proven to be a reliable technique for cartilage resurfacing. However, the prolonged storage of allografts comes at the expense of chondrocyte viability, which declines precipitously after 14 days under refrigeration. Despite this, radiographic data indicate that most allograft cartilage remains stable for years after implantation. The apparent durability of partially devitalized cartilage begs the question of how the extracellular matrix is maintained.

HYPOTHESIS

Compared with patients' defect cartilage, replacement OCAs freshly preserved for 36 days on average contain significantly lower levels of cartilage matrix-destructive metalloproteinases, which may contribute to the long-term stability of implanted grafts.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Chondrocyte density was determined by the cell yield from digested cartilage and by double-strand DNA content quantified with PicoGreen assay. Chondrocyte viability was estimated by staining enzymatically isolated chondrocytes with calcein AM and ethidium homodimer-2. Cartilage proteoglycan (PG) content was analyzed with dimethylmethylene blue assay. The in vitro 48-hour release of PG-depleting metalloproteinases including matrix metalloproteinase (MMP)-1, -3, -13, and ADAMTS-5 from cartilage was examined with Western blotting. The data were compared between diseased cartilage from patients and samples from matched grafts. The relative amount of MMP-3 to its endogenous inhibitor, tissue inhibitor of MMP-1 (TIMP-1), was also determined with Western blotting.

RESULTS

Chondrocyte density decreased linearly with allograft storage time and declined by an average of 43%. PG content decreased while the percentage of nonviable chondrocytes increased with storage time, with the former showing less linearity. However, PG content remained in the normal range and was significantly higher than that in patients' defect cartilage. Correspondingly, significantly less PG-depleting metalloproteinases and a much lower MMP-3/TIMP-1 ratio were detected in allograft cartilage than in patients' diseased cartilage.

CONCLUSION

These findings indicated that, at the time of implantation, fresh-preserved OCAs contained significantly lower levels of PG-depleting metalloproteinases compared with patients' defect cartilage, which might contribute to their long-term stability in vivo.

CLINICAL RELEVANCE

The comparatively low expression of cartilage-dissolving metalloproteinases in human OCAs freshly preserved over 30 days offers support to the long-term durability of implanted grafts. Based on study data that showed similarity in the response to inflammatory cytokines between patients' cartilage and OCA cartilage, strategies that can alleviate inflammation may provide extra benefit for the survival of implanted grafts. In terms of the practice of graft preservation, agents that can keep balance between the ATP supply and demand or stabilize the cell membrane or inhibit the activation of metalloproteinases may significantly improve cell viability in fresh-preserved OCAs with a storage time longer than 5 weeks.

Knee osteoarthritis: Clinical connections to articular cartilage structure and function

Articular cartilage is a unique biphasic material that supports a lifetime of compressive and shear forces across joints. When articular cartilage deteriorates, whether due to injury, wear and tear or normal aging, osteoarthritis and resultant pain can ensue. Understanding the basic science of the structure and biomechanics of articular cartilage can help clinicians guide their patients to appropriate activity and loading choices. The purpose of this article is to examine how articular cartilage structure and mechanics, may interact with risk factors to contribute to OA and how this interaction provides guidelines for intervention choices This paper will review the microstructure of articular cartilage, its mechanical properties and link this information to clinical decision making.

Low-intensity pulsed ultrasound promotes chondrogenic progenitor cell migration via focal adhesion kinase pathway

Low-intensity pulsed ultrasound (LIPUS) has been studied frequently for its beneficial effects on the repair of injured articular cartilage. We hypothesized that these effects are due to stimulation of chondrogenic progenitor cell (CPC) migration toward injured areas of cartilage through focal adhesion kinase (FAK) activation. CPC chemotaxis in bluntly injured osteochondral explants was examined by confocal microscopy, and migratory activity of cultured CPCs was measured in transwell and monolayer scratch assays. FAK activation by LIPUS was analyzed in cultured CPCs by Western blot. LIPUS effects were compared with the effects of two known chemotactic factors: N-formyl-methionyl-leucyl-phenylalanine (fMLF) and high-mobility group box 1 (HMGB1) protein. LIPUS significantly enhanced CPC migration on explants and in cell culture assays. Phosphorylation of FAK at the kinase domain (Tyr 576/577) was maximized by 5 min of exposure to LIPUS at a dose of 27.5 mW/cm(2) and frequency of 3.5 MHz. Treatment with fMLF, but not HMBG1, enhanced FAK activation to a degree similar to that of LIPUS, but neither fMLF nor HMGB1 enhanced the LIPUS effect. LIPUS-induced CPC migration was blocked by suppressing FAK phosphorylation with a Src family kinase inhibitor that blocks FAK phosphorylation. Our results imply that LIPUS might be used to promote cartilage healing by inducing the migration of CPCs to injured sites, which could delay or prevent the onset of post-traumatic osteoarthritis.

Joint instability and cartilage compression in a mouse model of posttraumatic osteoarthritis

Joint instability and cartilage trauma have been previously studied and identified as key mediators in the development of posttraumatic osteoarthritis (PTOA). The purpose of this study was to use an in vivo model to compare the effect of joint instability, caused by the rupture of the anterior cruciate ligament (ACL), versus cartilage compression. In this study, mice were subjected to cyclical axial loads of twelve Newtons (N) for 240 cycles or until the ACL ruptured. One and eight weeks after this procedure, knees were sectioned coronally and evaluated for osteoarthritis by histology. Using a scoring scale established by [Pritzker K, Gay S, Jimenez S, et al. (2006): Osteoarthritis Cartilage 14:13-29], the articular cartilage across each surface was scored and combined to produce a total degeneration score. The ACL-ruptured group had a significantly greater total degeneration score than either control or compression treated joints at 1 and 8 weeks. Additionally, only sections from ACL-ruptured knees consistently showed synovitis after 1 week and osteophyte formation after 8 weeks. Thus, it appears using that ACL rupture consistently creates a severe osteoarthritis phenotype, while axial cartilage compression alone does not appear to be an appropriate method of inducing PTOA in vivo.

Subphysiological compressive loading reduces apoptosis following acute impact injury in a porcine cartilage model

BACKGROUND

Acute cartilage injuries induce cell death and are associated with an increased incidence of osteoarthritis development later in life. The objective of this study was to investigate the effect of posttraumatic cyclic compressive loading on chondrocyte viability and apoptosis in porcine articular cartilage plugs.

HYPOTHESIS

Compressive loading of acutely injured cartilage can maintain chondrocyte viability by reducing apoptosis after a traumatic impact injury.

STUDY DESIGN

In vitro controlled laboratory study.

LEVEL OF EVIDENCE

Level 5.

METHODS

Each experiment compared 4 test groups: control, impact, impact with compressive loading (either 0.5 or 0.8 MPa), and no impact but compressive loading (n = 15 per group). Flat, full-thickness articular cartilage plugs were harvested from the trochlear region of porcine knees. A drop tower was utilized to introduce an impact injury. The articular plugs were subjected to two 30-minute cycles of either 0.5 or 0.8 MPa of dynamic loading. Cell viability, apoptosis, and gene expression of samples were evaluated 24 hours postimpaction.

RESULTS

Cell viability staining showed that 0.5 MPa of dynamic compressive loading increased cell viability compared with the impact group. Apoptotic analysis revealed a decrease in apoptotic expression in the group with 0.5 MPa of dynamic compressive loading compared with the impact group. Significantly higher caspase 3 and lower collagen II expressions were observed in impacted samples without compressive loading, compared with those with. Compressive loading of nonimpacted samples significantly increased collagen II and decreased caspase 3 expressions.

CONCLUSION

In this porcine in vitro model, dynamic compressive loading at subphysiological levels immediately following impact injury decreases apoptotic expression, thereby maintaining chondrocyte viability.

CLINICAL RELEVANCE

Therapeutic exercises could be designed to deliver subphysiological loading to the injured cartilage, thereby minimizing injury.

Lack of exercise is a major cause of chronic diseases

Chronic diseases are major killers in the modern era. Physical inactivity is a primary cause of most chronic diseases. The initial third of the article considers: activity and prevention definitions; historical evidence showing physical inactivity is detrimental to health and normal organ functional capacities; cause versus treatment; physical activity and inactivity mechanisms differ; gene-environment interaction (including aerobic training adaptations, personalized medicine, and co-twin physical activity); and specificity of adaptations to type of training. Next, physical activity/exercise is examined as primary prevention against 35 chronic conditions [accelerated biological aging/premature death, low cardiorespiratory fitness (VO2max), sarcopenia, metabolic syndrome, obesity, insulin resistance, prediabetes, type 2 diabetes, nonalcoholic fatty liver disease, coronary heart disease, peripheral artery disease, hypertension, stroke, congestive heart failure, endothelial dysfunction, arterial dyslipidemia, hemostasis, deep vein thrombosis, cognitive dysfunction, depression and anxiety, osteoporosis, osteoarthritis, balance, bone fracture/falls, rheumatoid arthritis, colon cancer, breast cancer, endometrial cancer, gestational diabetes, pre-eclampsia, polycystic ovary syndrome, erectile dysfunction, pain, diverticulitis, constipation, and gallbladder diseases]. The article ends with consideration of deterioration of risk factors in longer-term sedentary groups; clinical consequences of inactive childhood/adolescence; and public policy. In summary, the body rapidly maladapts to insufficient physical activity, and if continued, results in substantial decreases in both total and quality years of life. Taken together, conclusive evidence exists that physical inactivity is one important cause of most chronic diseases. In addition, physical activity primarily prevents, or delays, chronic diseases, implying that chronic disease need not be an inevitable outcome during life.

Is high-impact sports participation associated with bowlegs in adolescent boys?

PURPOSE

The purpose of this study was to investigate whether the participation in load bearing sports is associated with significant knee alignment adaptations in adolescent boys, which might cause a higher risk for the development of knee osteoarthritis in later life.

METHODS

Five hundred twenty-one healthy boys (from 7 to 18 yr), selected from local primary and secondary schools, participated in the study. Two hundred sixty-five of them practiced competitive sports (track and field, field hockey, basketball, volleyball, tennis, badminton, and squash) for at least 3 h·wk(-1). The other remaining 256 boys did not practice any kind of sports. Genu varum/valgum was determined by measuring the intercondylar (IC) and intermalleolar (IM) distance with the subjects in a relaxed erect standing position. The IC and/or IM distance was measured using a caliper. Both measurements were combined to one parameter: the IC-IM distance. A one-way ANOVA was performed to analyze differences between the different age groups within the sporting and nonsporting boys separately. For each age group, the IC-IM distances of the sporting and nonsporting boys were compared by ANOVA with post hoc Bonferroni corrections.

RESULTS

A comparison between the sporting and nonsporting boys showed that the sporting boys had a significantly higher degree of genu varum from 13 to 15 yr or older (P = 0.01).

CONCLUSIONS

From the results of this study, it can be concluded that practicing load bearing sports in general is associated with the same knee varus alignment in adolescent boys as previously has been indicated in intense soccer-playing adolescents.

Is lifelong knee joint force from work, home, and sport related to knee osteoarthritis?

Purpose. To investigate the association of cumulative lifetime knee joint force on the risk of self-reported medically-diagnosed knee osteoarthritis (OA). Methods. Exposure data on lifetime physical activity type (occupational, household, sport/recreation) and dose (frequency, intensity, duration) were collected from 4,269 Canadian men and women as part of the Physical Activity and Joint Heath cohort study. Subjects were ranked in terms of the "cumulative peak force index", a measure of lifetime mechanical knee force. Multivariable logistic regression was conducted to obtain adjusted effects for mean lifetime knee force on the risk of knee OA. Results. High levels of total lifetime, occupational and household-related force were associated with an increased in risk of OA, with odds ratio's ranging from approximately 1.3 to 2. Joint injury, high BMI and older age were related to risk of knee OA, consistent with previous studies. Conclusions. A newly developed measure of lifetime mechanical knee force from physical activity was employed to estimate the risk of self-reported, medically-diagnosed knee OA. While there are limitations, this paper suggests that high levels of total lifetime force (all domains combined), and occupational force in men and household force in women were risk factors for knee OA.

Knee and ankle osteoarthritis in former elite soccer players: a systematic review of the recent literature

OBJECTIVES

To investigate the prevalence of knee and/or ankle osteoarthritis in former elite soccer player.

DESIGN

Systematic review.

METHODS

Medline, Embase and SPORTDiscus (2000 to January 2012) were used. To be included, studies were required to be a primary study, written in English, Dutch, French or German, former elite soccer players had to be the study population, and presenting knee or ankle OA had to be the outcome measure.

RESULTS

The search strategy resulted in four studies. Two studies, evaluated as having a high methodological quality, found a prevalence rate of knee OA between 60 and 80%. Both studies used radiographic examination as their measurement instrument to diagnose OA; the presence of ankle OA was not determined. The other two studies, evaluated as having a moderate methodological quality, found a prevalence rate of knee OA between 40 and 46% and a prevalence rate of ankle OA between 12 and 17%. These studies used a questionnaire as their measurement instrument wherein players were asked if they had ever been diagnosed with OA by a medical specialist.

CONCLUSIONS

The prevalence of knee and ankle OA in former elite soccer players can be considered high compared to the general population and to other occupations. To identify players at risk for OA, a health surveillance program should be implemented in elite soccer as a preventive measure. Further research should be conducted to determine if the risk of developing OA varies among different subgroups of elite soccer players and what the consequences of this high OA prevalence are.

Critical-size defect induces unicompartmental osteoarthritis in a stable ovine knee

Animal models simulating osteoarthritis are frequently associated with irreversible changes in biomechanics. Although these models successfully induce osteoarthritis, results of experimental repair procedures are impaired by biomechanical problems. The aim of this study was to define the critical size of a chondral lesion to induce unicompartmental osteoarthritis in a stable joint. Sixteen sheep were randomly divided into four treatment groups. A cartilage defect (7- or 14-mm diameter) was created in the weight-bearing zone of the medial femoral condyle. The sheep were mobilized for 6 or 12 weeks. Osteoarthritis was determined by gross assessment, India ink staining, histology (Mankin score), and analysis of COMP in the serum. In the 6-week group, only minor osteoarthritis was registered for either defect size. After 12 weeks, the 14-mm defect induced minor osteoarthritis at the femoral condyle and caused significant degenerative changes at the tibial articular cartilage and the meniscus. The 7-mm defect created focal unicompartmental osteoarthritis at the medial femoral condyle and minor degenerative changes at the corresponding tibia. A 7-mm full-thickness chondral defect with a weight-bearing regimen of 12 weeks induced local osteoarthritis at the medial compartment in an otherwise stable joint as aimed.

A phenomenological mathematical model of the articular cartilage damage

Articular cartilage (AC) is a biological tissue that allows the distribution of mechanical loads and movement of joints. The presence of these mechanical loads influences the behavior and physiological condition of AC. The loads may cause damaged by fatigue through injuries due to repeated accumulated stresses. The aim of this work is to introduce a phenomenological mathematical model of damage caused by mechanical action. It is considered that tissue failure is a consequence of chondrocyte death and matrix loss, taking into account factors modifying fatigue resistance such as age, body mass index (BMI) and metabolic activity. The model was numerically implemented using the finite elements method and the results obtained allowed us to predict tissue failure at different loading frequencies, different damage sites and variations in damage magnitude. Qualitative concordance between numerical results and experimental data led us to conclude that the model may be useful for physicians and therapists as a prediction tool for prescribing physical exercise and prognosis of joint failure.

Risk of severe knee and hip osteoarthritis in relation to level of physical exercise: a prospective cohort study of long-distance skiers in Sweden

BACKGROUND

To complete long-distance ski races, regular physical exercise is required. This includes not only cross-country skiing but also endurance exercise during the snow-free seasons. The aim of this study was to determine whether the level of physical exercise is associated with future risk of severe osteoarthritis independent of previous diseases and injuries.

METHODOLOGY/PRINCIPAL FINDINGS

We used a cohort that consisted of 48 574 men and 5 409 women who participated in the 90 km ski race Vasaloppet at least once between 1989 and 1998. Number of performed races and finishing time were used as estimates of exercise level. By matching to the National Patient Register we identified participants with severe osteoarthritis, defined as arthroplasty of knee or hip due to osteoarthritis. With an average follow-up of 10 years, we identified 528 men and 42 women with incident osteoarthritis. The crude rate was 1.1/1000 person-years for men and 0.8/1000 person-years for women. Compared with racing once, participation in ≥ 5 races was associated with a 70% higher rate of osteoarthritis (multivariable-adjusted hazard ratio (HR) 1.72, 95% confidence interval (CI) 1.33 to 2.22). The association was dose-dependent with an adjusted HR of 1.09, 95% CI 1.05 to 1.13 for each completed race. A faster finishing time, in comparison with a slow finishing time, was also associated with an increased rate (adjusted HR 1.51, 95% CI 1.14 to 2.01). Contrasting those with 5 or more ski races and a fast finish time to those who only participated once with a slow finish time, the adjusted HR of osteoarthritis was 2.73, 95% CI 1.78 to 4.18.

CONCLUSIONS/SIGNIFICANCE

Participants with multiple and fast races have an increased risk of subsequent arthroplasty of knee and hip due to osteoarthritis, suggesting that intensive exercise may increase the risk.

Mechanical impact induces cartilage degradation via mitogen activated protein kinases

OBJECTIVE

To determine the activation of Mitogen activated protein (MAP) kinases in and around cartilage subjected to mechanical damage and to determine the effects of their inhibitors on impaction-induced chondrocyte death and cartilage degeneration.

DESIGN

The phosphorylation of MAP kinases was examined with confocal microscopy and immunoblotting. The effects of MAP kinase inhibitors on impaction-induced chondrocyte death and proteoglycan (PG) loss were determined with fluorescent microscopy and 1, 9-Dimethyl-Methylene Blue (DMMB) assay. The expression of catabolic genes at mRNA levels was examined with quantitative real-time PCR.

RESULTS

Early p38 activation was detected at 20 min and 1h post-impaction. At 24h, enhanced phosphorylation of p38 and extracellular signal-regulated protein kinase (ERK)1/2 was visualized in chondrocytes from in and around impact sites. The phosphorylation of p38 was increased by 3.0-fold in impact sites and 3.3-fold in adjacent cartilage. The phosphorylation of ERK-1 was increased by 5.8-fold in impact zone and 5.4-fold in adjacent cartilage; the phosphorylation of ERK-2 increased by 4.0-fold in impacted zone and 3.6-fold in adjacent cartilage. Furthermore, the blocking of p38 pathway did not inhibit impaction-induced ERK activation. The inhibition of p38 or ERK pathway significantly reduced injury-related chondrocyte death and PG losses. Quantitative Real-time PCR analysis revealed that blunt impaction significantly up-regulated matrix metalloproteinase (MMP)-13, Tumor necrosis factor (TNF)-α, and ADAMTS-5 expression.

CONCLUSION

These findings implicate p38 and ERK mitogen activated protein kinases (MAPKs) in the post-injury spread of cartilage degeneration and suggest that the risk of post-traumatic osteoarthritis (PTOA) following joint trauma could be decreased by blocking their activities, which might be involved in up-regulating expressions of MMP-13, ADAMTS-5, and TNF-α.

Increased risk of knee injuries and osteoarthritis in the non-dominant leg of former professional football players

The aim of the study was to evaluate differences in knee injuries and osteoarthritis between the dominant and non-dominant legs of former professional football players. The study cohort comprised 40 retired professional players with an average age of 49.2 years. Participants completed a questionnaire about their sports and personal history with special emphasis on knee injuries/operations of the dominant and non-dominant leg. Bilateral standing knee radiographs were taken. Overall, 29 footballers (73%) had experienced at least one moderate or severe knee injury and 18 (40%) had undergone at least one knee operation during their career. Among those injured, 14 (35%) players had suffered a dominant knee injury and 22 (55%) a non-dominant knee injury. Evidence of osteoarthritis (Kellgren-Lawrence scale > or = 2) was found in 17 (43%) dominant and 23 (58%) non-dominant knees. Professional football players have a significant risk of knee injuries and early osteoarthritis with preponderance in the non-dominant leg.

Effects of introducing cultured human chondrocytes into a human articular cartilage explant model

Articular cartilage (AC) heals poorly and effective host-tissue integration after reconstruction is a concern. We have investigated the ability of implanted chondrocytes to attach at the site of injury and to be incorporated into the decellularized host matrix adjacent to a defect in an in vitro human explant model. Human osteochondral dowels received a standardized injury, were seeded with passage 3 chondrocytes labelled with PKH 26 and compared with two control groups. All dowels were cultured in vitro, harvested at 0, 7, 14 and 28 days and assessed for chondrocyte adherence and migration into the region of decellularized tissue adjacent to the defects. Additional evaluation included cell viability, general morphology and collagen II production. Seeded chondrocytes adhered to the standardized defect and areas of lamina splendens disruption but did not migrate into the adjacent acellular region. A difference was noted in viable-cell density between the experimental group and one control group. A thin lattice-like network of matrix surrounded the seeded chondrocytes and collagen II was present. The results indicate that cultured human chondrocytes do indeed adhere to regions of AC matrix injury but do not migrate into the host tissue, despite the presence of viable cells. This human explant model is thus an effective tool for studying the interaction of implanted cells and host tissue.

Does loading influence the severity of cartilage degeneration in the canine Groove-model of OA?

Many animal models are used to study osteoarthritis (OA). In these models the role of joint loading in the development of OA is not fully understood. We studied the effect of loading on the development of OA in the canine Groove-model. In ten female beagle dogs OA was induced in one knee according to the Groove-model. The animals were divided in groups with and without forced-loading. Forced-loading was achieved by fixing the contra-lateral limb to the trunk 3 times a week for 4 hours. After 20 weeks joint tissues of all dogs were evaluated. Subjective evaluation revealed less movement with more loading in the forced-loading-group compared to the group without forced-loading. In both groups induction of OA resulted in macroscopical and microscopical OA changes as well as alterations in cartilage metabolism characteristics for OA. Although differences were small, for some parameters they were statistically significant for the forced-loading-group. There were no differences between the contra-lateral healthy joints of both groups. The present study demonstrates that in the Groove-model intensified loading is not a prerequisite for the development of OA, although it adds to some extent to the severity of the OA.

T1rho, T2 and focal knee cartilage abnormalities in physically active and sedentary healthy subjects versus early OA patients--a 3.0-Tesla MRI study

(1) To assess the degree of focal cartilage abnormalities in physically active and sedentary healthy subjects as well as in patients with early osteoarthritis (OA). (2) To determine the diagnostic value of T2 and T1rho measurements in identifying asymptomatic physically active subjects with focal cartilage lesions. Thirteen asymptomatic physically active subjects, 7 asymptomatic sedentary subjects, and 17 patients with mild OA underwent 3.0-T MRI of the knee joint. T1rho and T2 values, cartilage volume and thickness, as well as the WORMS scores were obtained. Nine out of 13 active healthy subjects had focal cartilage abnormalities. T1rho and T2 values in active subjects with and without focal cartilage abnormalities differed significantly (p < 0.05). T1rho and T2 values were significantly higher (p < 0.05) in early OA patients compared to healthy subjects. T1rho measurements were superior to T2 in differentiating OA patients from healthy subjects, yet T1rho was moderately age-dependent. (1) Active subjects showed a high prevalence of focal cartilage abnormalities and (2) active subjects with and without focal cartilage abnormalities had different T1rho and T2 composition of cartilage. Thus, T1rho and T2 could be a parameter suited to identify active healthy subjects at higher risk for developing cartilage pathology.

Prevalence of pathologic findings in asymptomatic knees of marathon runners before and after a competition in comparison with physically active subjects-a 3.0 T magnetic resonance imaging study

PURPOSE

To determine the prevalence of pathologic findings in asymptomatic knees of marathon runners before and after a competition in comparison with physically active subjects. To compare the diagnostic performance of cartilage-dedicated magnetic resonance imaging (MRI) sequences at 3.0 T.

MATERIALS AND METHODS

Ten marathon runners underwent 3.0 T MRI 2-3 days before and after competition. Twelve physically active asymptomatic subjects not performing long-distance running were examined as controls. Pathologic condition was assessed with the whole-organ magnetic resonance imaging score (WORMS). Cartilage abnormalities and bone marrow edema pattern (BMEP) were quantified. Visualization of cartilage pathology was assessed with intermediate-weighted fast spin-echo (IM-w FSE), fast imaging employing steady-state acquisition (FIESTA) and T1-weighted three-dimensional (3D) high-spatial-resolution volumetric fat-suppressed spoiled gradient-echo (SPGR) MRI sequences.

RESULTS

Eight of ten marathon runners and 7/12 controls showed knee abnormality. Slightly more and larger cartilage abnormalities, and BMEP, in marathon runners yielded higher but not significantly different WORMS (P > 0.05) than in controls. Running a single marathon did not alter MR findings substantially. Cartilage abnormalities were best visualized with IM-w FSE images (P < 0.05).

CONCLUSION

A high prevalence of knee abnormalities was found in marathon runners and also in active subjects participating in other recreational sports. IM-w FSE sequences delineated more cartilage MR imaging abnormalities than did FIESTA and SPGR sequences.

Autologous interleukin-1 receptor antagonist improves function and symptoms in osteoarthritis when compared to placebo in a prospective randomized controlled trial

INTRODUCTION

Incubation of blood with CrSO(4)-coated glass beads stimulates the synthesis of anti-inflammatory cytokines, such as interleukin-1 receptor antagonist (IL-1ra), IL-4, IL-10, and IL-13. As IL-1beta is thought to play a key role in the development of osteoarthritis (OA), this product, also known as Orthokin, might be a viable treatment for symptomatic knee OA. The aim of the current study was to evaluate the efficacy of Orthokin for treatment of symptomatic knee OA in a randomized, multicentre, double-blind, placebo-controlled trial.

PATIENTS AND METHODS

One hundred and sixty-seven patients received six intra-articular injections either with Orthokin or physiological saline. The primary efficacy objective consisted of 30% superiority on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 3, 6, 9, and 12 months post-treatment. Additionally, the patients completed the visual analogue scale for pain, the Knee injury and Osteoarthritis Outcome Score (KOOS) and Knee Society Clinical Rating System.

RESULTS

Orthokin and placebo treatment resulted in similar improvements on the WOMAC (16.8% vs 16.5%, respectively; n.s.). Orthokin resulted in significantly more improvement for KOOS symptom (P = 0.002) and KOOS sport (P = 0.042) parameters as compared to placebo treatment. For most other outcome parameters, Orthokin-treated patients consistently showed higher improvement compared to placebo-treated patients, although none of these differences were statistically significant. Two serious adverse events were observed in the Orthokin group: one patient with repeated severe inflammatory reactions of the knee joint within hours after the injection and one patient with septic arthritis which was attributed to the injection procedure rather than the product.

CONCLUSION

The statistically significant improvement of KOOS symptom and sport parameters together with the consistently higher, though non-statistically significant, improvement of most other parameters demonstrates that Orthokin clearly induces a biological response different from placebo treatment and warrant future investigations into the possible chondroprotective effect of Orthokin. However, in the current study the primary efficacy objective was not met and, therefore, the use of Orthokin currently cannot yet be recommended for the treatment of OA.

Calcium signaling leads to mitochondrial depolarization in impact-induced chondrocyte death in equine articular cartilage explants

OBJECTIVE

Chondrocyte apoptosis is an important factor in the progression of osteoarthritis. This study aimed to elucidate the mechanisms involved upstream of caspase 9 activation and, in particular, calcium signaling and mitochondrial depolarization.

METHODS

Articular cartilage explants obtained from healthy horses were subjected to a single impact load (500-gm weight dropped from a height of 50 mm) and cultured in vitro for up to 48 hours. Chondrocyte death was quantified by the TUNEL method. Release of proteoglycans was determined by the dimethylmethylene blue assay. Weight change was measured, and mitochondrial depolarization was determined using JC-1 staining. To assess the role of calcium signaling in impact-induced chondrocyte death, explants were preincubated in culture medium containing various concentrations of calcium. Inhibitors were used to assess the role of individual signaling components in impact-induced chondrocyte death.

RESULTS

Calcium quenching, inhibitors of calpains, calcium/calmodulin-regulated kinase II (CaMKII), and mitochondrial depolarization reduced impact-induced chondrocyte death after 48 hours in culture. Transient mitochondrial depolarization was observed 3-6 hours following a single impact load. Mitochondrial depolarization was prevented by calcium quenching, inhibitors of calpain, CaMKII, permeability transition pore formation, ryanodine receptor, and the mitochondrial uniport transporter. Cathepsin B did not appear to be involved in impact-induced chondrocyte death. The calpain inhibitor prevented proteoglycan loss, but the percentage weight gain and proteoglycan loss were unaffected by all treatments used.

CONCLUSION

Following a single impact load, calcium is released from the endoplasmic reticulum via the ryanodine receptor and is taken up by the mitochondria via the uniport transporter, causing mitochondrial depolarization and caspase 9 activation. In addition, calpains and CaMKII play important roles in causing mitochondrial depolarization.

Inhibition of caspase-9 reduces chondrocyte apoptosis and proteoglycan loss following mechanical trauma

OBJECTIVE

Chondrocyte death, a notable feature of osteoarthritis, may play a role in the initiation of cartilage degeneration. The present study was aimed at uncovering the nature and involvement of cell death in the initiation of cartilage degeneration induced by mechanical trauma.

METHODS

Articular cartilage discs obtained from healthy skeletally mature horses were subjected to a single-impact load (500 g from 50 mm) using a simple drop-tower device and cultured in vitro for 48 h. Chondrocyte death was examined using two independent methods: transmission electron microscopy and caspase-3 activity assay. To elucidate the signalling mechanisms involved in impact-induced cell death measured by terminal deoxynucleotidyl transferase-deoxyuridine triphosphate (dUTP) nick-end labelling (TUNEL), cartilage discs were incubated with specific caspase-3, -8 and -9 inhibitors prior to impact. Additionally, weight gain and glycosaminoglycan (GAG) release, markers of cartilage degeneration were monitored.

RESULTS

After 48 h, ultrastructural evidence of apoptosis was observed. Caspase-3 was activated after 12h of culture post-impact. When quantified by TUNEL, impact trauma induced death in 52.6% of superficial chondrocytes after 48 h in culture, compared to 4.2% in unimpacted controls. Specific caspases-3 and -9 inhibitors significantly reduced impact-induced apoptosis to 24.3% and 14.7%, respectively. Caspase-8 inhibition had no effect on chondrocyte death (60.3%). Impact-induced GAG release into the medium was significantly reduced by inhibition of cell death, but weight gain remained unaffected by caspase inhibition.

CONCLUSION

These results suggest that impact trauma-induced chondrocyte death is predominantly due to caspase-9-dependent apoptosis and is linked to cartilage degeneration.