Individual risk factors for hip osteoarthritis: obesity, hip injury, and physical activity

Risk of Osteoarthritis and Arthroplasty Between Baclofen and Tizanidine: A Target Trial Emulation Study

BACKGROUND

Preclinical studies have shown that baclofen may reduce the risk of osteoarthritis through its anti-inflammatory effect.

OBJECTIVE

We aimed to clarify this association by comparing the risks of osteoarthritis and joint replacement surgery in patients receiving baclofen and tizanidine.

METHODS

This retrospective cohort study was conducted on the global TriNetX platform (October 31, 2024). New users of baclofen and tizanidine aged ≥40 years were included in the baclofen and tizanidine group, respectively. The propensity score matching method was used. The primary outcomes were osteoarthritis and joint replacement surgery. The secondary outcomes included all-cause mortality, a composite outcome of osteoarthritis and all-cause mortality, and a composite outcome of joint replacement surgery and all-cause mortality. Cause specific hazard ratios (HRs) with 95% confidence intervals (CIs) of the outcomes were calculated with Cox regression using the TriNetX platform.

RESULTS

Two well-balanced groups containing 68,210 patients each were generated by propensity score matching (age: 57.8 years; female: 55.6% in both groups). Baclofen users had a significantly lower risk of developing osteoarthritis than tizanidine users (HR: 0.965, 95% CI: 0.941 to 0.989). A similar relationship was observed for joint replacement surgery (HR: 0.847, 95% CI: 0.750 to 0.956). However, the composite outcome of osteoarthritis or death had a HR of 1.129 (95% CI: 1.109 to 1.150), and the HR of joint replacement surgery or death was 1.509 (95% CI: 1.463 to 1.556). The HR of death was 1.577 (95% CI: 1.527 to 1.629), suggesting a higher risk of mortality in the baclofen group.

CONCLUSION

The surviving baclofen users had a lower risk of osteoarthritis and joint replacement surgery compared to surviving tizanidine users. However, baclofen users exhibited a higher risk of mortality than tizanidine users. Future studies are necessary to clarify the impact of baclofen on osteoarthritis and joint replacement surgery while accounting for mortality.

Does Surgical Approach in Total Hip Arthroplasty Affect Postoperative Corticosteroid Injection Requirements?

BACKGROUND

Corticosteroid injections following total hip arthroplasty (THA) are commonly used to address soft tissue pathology such as bursitis and tendinitis. The THA surgical approaches differ in the extent of muscle and soft tissue dissection. The aim of this study was to compare the impact of surgical approach on postoperative corticosteroid injection requirements when controlling for multiple covariates. A secondary aim was to identify risk factors associated with the various injection types.

METHODS

This was a propensity-matched retrospective study of 10,907 THA patients from June 2016 to December 2022 at a single urban academic health center. Patients were stratified into cohorts based on the following surgical approaches: anterior (n = 4,287) and posterior (n = 6,620), then propensity-matched 1:1 with nearest neighbor matching to form two cohorts of 4,287 patients. Baseline characteristics and corticosteroid injection data for soft-tissue pathology were obtained and analyzed. Chi-square and multivariate logistic regression analyses were used to assess the impact of patient and surgical factors on receiving postoperative steroid injections.

RESULTS

A posterior approach conferred increased risk of postoperative injections (adjusted odds ratio 1.242, P = 0.001) after controlling for multiple covariates. The posterior approach also had higher total rates of greater trochanter bursitis injections postoperatively compared to the anterior group (11.5 versus 7.3%, P < 0.001). Both surgical approaches demonstrated comparable rates of iliopsoas bursitis injections (P = 0.39), gluteus medius tendinosis injections (P = 0.09), and lateral femoral cutaneous nerve injections (P = 0.27). The strongest predictor of postoperative injections was a history of preoperative injection (adjusted odds ratio 3.772, P < 0.001).

CONCLUSIONS

Posterior approach, women, and history of preoperative corticosteroid injection were identified as the strongest risk factors for postoperative greater trochanter bursitis injection or postoperative soft tissue injection. These factors should be considered when counseling patients on expected postoperative outcomes and the likelihood of corticosteroid injections following THA.

Short-term prediction of clinical and radiographic contralateral hip osteoarthritis after index total hip arthroplasty

INTRODUCTION

Patients with primary hip osteoarthritis undergoing unilateral total hip arthroplasty (THA) often face uncertainty about the future need for arthroplasty in the contralateral hip. We aimed to identify parameters that have predictive value with regard to the necessity for contralateral THA or the development of contralateral radiographic osteoarthritis (OA) phenotypes following index surgery.

MATERIALS AND METHODS

In this retrospective study, we analyzed 220 patients undergoing THA. Of these, 24.1% required contralateral THA at a mean follow-up of 18.3months. Our assessments included preoperative and follow-up pelvis radiographs as well as bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry prior to index THA. Comprehensive radiological measurements such as the Kellgren-Lawrence OA grade, osteophyte evaluation as well as joint shape and alignment (including alpha and CE angles) were performed.

RESULTS

We identified three indicators at the initial assessment for predicting the need for contralateral THA: higher BMI (odds ratio (OR) 1.1 [95%-CI 1.0-1.2], p = 0.033), higher alpha angles (> 61.5°) (OR 2.5 [95%-CI 1.0-6.3], p = 0.045) and the presence of multiple osteophytes (OR 2.6 [95%-CI 1.4-4.9], p = 0.004). Moreover, higher alpha angles were linked to more severe radiographic OA, especially osteophytosis. Higher BMD T-scores were also associated with progressive formation of multiple and large osteophytes but not joint space narrowing.

CONCLUSION

Three factors - BMI, alpha angle, and osteophyte number - are key short-term predictors for contralateral THA after index THA. We also identified BMD as a surrogate for osteophyte formation. These findings provide novel and valuable insights for patients and surgeons regarding risks and counseling for contralateral OA and THA.

Greater myofibrillar protein synthesis following weight-bearing activity in obese old compared with non-obese old and young individuals

The mechanisms through which obesity impacts age-related muscle mass regulation are unclear. In the present study, rates of integrated myofibrillar protein synthesis (iMyoPS) were measured over 48-h prior-to and following a 45-min treadmill walk in 10 older-obese (O-OB, body fat[%]: 33 ± 3%), 10 older-non-obese (O-NO, 20 ± 3%), and 15 younger-non-obese (Y-NO, 13 ± 5%) individuals. Surface electromyography was used to determine thigh muscle "activation". Quadriceps cross-sectional area (CSA), volume, and intramuscular thigh fat fraction (ITFF) were measured by magnetic resonance imaging. Quadriceps maximal voluntary contraction (MVC) was measured by dynamometry. Quadriceps CSA and volume were greater (muscle volume, Y-NO: 1182 ± 232 cm3; O-NO: 869 ± 155 cm3; O-OB: 881 ± 212 cm3, P < 0.01) and ITFF significantly lower (m. vastus lateralis, Y-NO: 3.0 ± 1.0%; O-NO: 4.0 ± 0.9%; O-OB: 9.1 ± 2.6%, P ≤ 0.03) in Y-NO compared with O-NO and O-OB, with no difference between O-NO and O-OB in quadriceps CSA and volume. ITFF was significantly higher in O-OB compared with O-NO. Relative MVC was lower in O-OB compared with Y-NO and O-NO (Y-NO: 5.5 ± 1.6 n·m/kg-1; O-NO: 3.9 ± 1.0 n·m/kg-1; O-OB: 2.9 ± 1.1 n·m/kg-1, P < 0.0001). Thigh muscle "activation" during the treadmill walk was greater in O-OB compared with Y-NO and O-NO (Y-NO: 30.5 ± 13.5%; O-NO: 35.8 ± 19.7%; O-OB: 68.3 ± 32.3%, P < 0.01). Habitual iMyoPS did not differ between groups, whereas iMyoPS was significantly elevated over 48-h post-walk in O-OB (+ 38.6 ± 1.2%·day-1, P < 0.01) but not Y-NO or O-NO (+ 11.4 ± 1.1%·day-1 and + 17.1 ± 1.1%·day-1, respectively, both P > 0.271). Equivalent muscle mass in O-OB may be explained by the muscle anabolic response to weight-bearing activity, whereas the age-related decline in indices of muscle quality appears to be exacerbated in O-OB and warrants further exploration.

Preoperative Laboratory Values Predicting Periprosthetic Joint Infection in Morbidly Obese Patients Undergoing Total Hip or Knee Arthroplasty

BACKGROUND

Morbidly obese patients are an ever-growing high-risk population undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) for end-stage osteoarthritis. This study sought to identify preoperative laboratory values that may serve as predictors of periprosthetic joint infection (PJI) in morbidly obese patients undergoing THA or TKA.

METHODS

All morbidly obese patients with preoperative laboratory data before undergoing primary elective TKA or THA were identified using the Premier Healthcare Database. Patients who developed PJI within 90 days after surgery were compared with patients without PJI. Laboratory value thresholds were defined by clinical guidelines or primary literature. Univariate and multivariable regression analyses were utilized to assess the association between PJI and preoperative laboratory values, including total lymphocyte count, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), monocyte-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), albumin level, platelet count, albumin-globulin ratio, hemoglobin level, and hemoglobin A1c.

RESULTS

Of the 6,780 patients identified (TKA: 76.67%; THA: 23.33%), 47 (0.69%) developed PJI within 90 days after surgery. The rate of PJI was 1.69% for patients with a hemoglobin level of <12 g/dL (for females) or <13 g/dL (for males), 2.14% for those with a platelet count of <142,000/µL or >417,000/µL, 1.11% for those with an NLR of >3.31, 1.69% for those with a PLR of >182.3, and 1.05% for those with an SII of >776.2. After accounting for potential confounding factors, we observed an association between PJI and an abnormal preoperative NLR (adjusted odds ratio [aOR]: 2.38, 95% confidence interval [CI]: 1.04 to 5.44, p = 0.039), PLR (aOR: 4.86, 95% CI: 2.15 to 10.95, p < 0.001), SII (aOR: 2.44, 95% CI: 1.09 to 5.44, p = 0.029), platelet count (aOR: 3.50, 95% CI: 1.11 to 10.99, p = 0.032), and hemoglobin level (aOR: 2.62, 95% CI: 1.06 to 6.50, p = 0.038).

CONCLUSIONS

This study identified preoperative anemia, abnormal platelet count, and elevated NLR, PLR, and SII to be associated with an increased risk of PJI among patients with a body mass index of ≥40 kg/m 2 . These findings may help surgeons risk-stratify this high-risk patient population.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Increased alcohol intake is associated with radiographic severity of knee and hand osteoarthritis in men

Observational studies have shown controversial associations between alcohol intake and radiographic osteoarthritis (OA). This study investigated whether this association was causal using a Mendelian randomization (MR) study in a population-based cohort in Korean. The study enrolled 2429 subjects (1058 men, 1371 women) from the Dong-gu Study. X-rays of the hand and knee joints were scored using a semi-quantitative grading system to calculate the total score of the hand and knee joints. ALDH2 rs671 genotyping was performed by high-resolution melting analysis. MR instrumental variable analysis and observational multivariable regression analysis were used to estimate the association between genetically predicted alcohol intake and the radiographic severity of OA. Subjects with the G/G genotype had a higher current alcohol intake than those with the G/A and A/A genotypes in both men and women (all P < 0.001). Men with the G/G genotype had higher total knee (P < 0.001) and hand scores (P = 0.042) compared to those with the G/A and A/A genotypes after adjusting for age and body mass index, but not in women. In the observational multivariable regression analysis, each alcohol drink per day in men was associated with increased knee (P = 0.001) and hand joint scores (P = 0.013) after adjustment, but not in women. In our MR analysis, utilizing ALDH2 rs671 genotypes as instrumental variables for alcohol consumption, has shown a significant link between each additional daily alcohol drink and increased radiographic joint severity in men.

Are Patient Outcomes Affected by Surgeon Experience With Total Hip Arthroplasty in Morbidly Obese Patients?

Background

Surgeons with high volume (HV) of total hip arthroplasty (THA) have seen better outcomes than low volume (LV) surgeons. However, literature regarding surgeon volume and outcomes in morbidly obese THA patients is scarce. This study examines the association between surgeon volume with THA in morbidly obese patients (body mass index ≥40) and their clinical outcomes.

Methods

We retrospectively reviewed all morbidly obese patients who underwent primary THA at our institution between March 2012 and July 2020 with 2 years of follow-up. Clinical outcomes were compared between the HV (HVa, top quartile of surgeons with the highest overall yearly THA volume) and LV (LVa) surgeons. Similar analysis was run comparing HV of morbidly obese THA (HVo, top quartile of surgeons with the highest yearly morbidly obese THA volume) and LV of morbidly obese THA (LVo) surgeons.

Results

Six hundred and forty-three patients and 33 surgeons were included. HVa surgeons had significantly shorter length of stay and increased home discharge. HVa and HVo surgeons had significantly shorter operative times. There were no significant differences in overall 90-day major and minor complications or clinical differences in patient-reported outcomes. Revision rates and freedom from revisions did not differ between groups at 2-year follow-up.

Conclusions

HVa surgeons had significantly lower length of stay and operative times and increased discharge to home. There was no significant decrease in complications or revisions in either comparison model. Complications, revision rates, and patient satisfaction in morbidly obese patients who undergo THA may be independent of surgeon volume.

Collaborative Ambulatory Orthopaedic Care in Patients with Hip and Knee Osteoarthritis: A Retrospective Comparative Cohort Study on Health Utilisation and Economic Outcomes

Objective

To evaluate a novel healthcare programme for the treatment of patients with hip and knee osteoarthritis in southern Germany in terms of clinical and health economic outcomes. The study is based on claims data from 2014 to 2017.

Methods

We conducted a retrospective comparative cohort study of 9768 patients with hip and knee osteoarthritis, of whom 9231 were enrolled in a collaborative ambulatory orthopaedic care programme (intervention group), and 537 patients received usual orthopaedic care (control group). Key features of the programme are coordinated care, morbidity-adapted reimbursement and extended consultation times. Multivariable analysis was performed to determine effects on health utilisation outcomes. The economic analysis considered annual costs per patient from a healthcare payer perspective, stratified by healthcare service sector. Besides multivariable regression analyses, bootstrapping was used to estimate confidence intervals for predicted mean costs by group.

Results

Musculoskeletal-disease-related hospitalisation was much less likely among intervention group patients than control group patients [odds ratio (OR): 0.079; 95% CI: 0.062-0.099]. The number of physiotherapy prescriptions per patient was significantly lower in the intervention group (RR: 0.814; 95% CI: 0.721-0.919), while the likelihood of participation in exercise programmes over one year was significantly higher (OR: 3.126; 95% CI: 1.604-6.094). Enrolment in the programme was associated with significantly higher ambulatory costs (€1048 vs. €925), but costs for inpatient care, including hospital stays, were significantly lower (€1003 vs. €1497 and €928 vs. €1300 respectively). Overall annual cost-savings were €195 per patient.

Conclusions

Collaborative ambulatory orthopaedic care was associated with reduced hospitalisation in patients with hip and knee osteoarthritis. Health costs for programme participants were lower overall, despite higher costs for ambulatory care.

The Association of Metabolic Syndrome and Obesity With Clinical Hip Osteoarthritis in the Study of Osteoporotic Fractures and the Osteoporotic Fractures in Men Study Cohorts

OBJECTIVE

Metabolic dysregulation frequently co-occurs with obesity, which has been shown to be a risk factor for lower extremity osteoarthritis (OA). We evaluated the association between metabolic syndrome (MetS), alone and in combination with obesity, and hip OA.

METHODS

In two parallel cross-sectional analyses, we studied 403 women from the Study of Osteoporotic Fractures (SOF) and 2354 men from the Osteoporotic Fractures in Men (MrOS) study. We used multivariable logistic regression to evaluate associations of obesity (body mass index ≥30 kg/m2 ) and/or MetS (three of five National Cholesterol Education Program Adult Treatment Panel III criteria) with clinical hip OA, defined as a modified Croft score of 2 or more or total hip replacement, and pain or limited range of motion. Our analysis adjusted for demographics.

RESULTS

Approximately 3.5% of SOF women and 5.4% of MrOS men had clinical hip OA. Among women, obesity was not associated with hip OA, yet those with MetS had a 365% higher odds of hip OA (95% CI: 1.37-15.83). Among men, those who had obesity had a 115% higher odds of hip OA (95% CI: 1.39-3.32), yet MetS was not associated with hip OA. There was no interaction between MetS, obesity, and hip OA in either women or men.

CONCLUSION

In women, but not in men, MetS was associated with hip OA. In men, but not in women, obesity was associated with hip OA. These findings suggest that mechanical effects of obesity may predominate in the pathogenesis of hip OA in men, whereas metabolic effects predominate in women.

Differences in opioid prescription rates between patients with musculoskeletal disorders enrolled in coordinated ambulatory healthcare and patients receiving usual care: a retrospective observational cohort study

OBJECTIVES

To compare opioid prescription rates between patients enrolled in coordinated ambulatory care and patients receiving usual care.

DESIGN

In this retrospective cohort study, we analysed claims data for insured patients with non-specific/specific back pain or osteoarthritis of hip or knee from 2014 to 2017.

SETTING

The study was based on administrative data provided by the statutory health insurance fund 'Allgemeine Ortskrankenkasse', in the state of Baden-Wurttemberg, Germany.

PARTICIPANTS

The intervention group consisted of patients enrolled in a coordinated ambulatory healthcare model; the control group included patients receiving usual care. Outcomes were overall strong and weak opioid prescriptions. Generalised linear regression models were used to analyse the effect of the intervention.

RESULTS

Overall, 46 001 (non-specific 18 787/specific 27 214) patients with back pain and 19 366 patients with osteoarthritis belonged to the intervention group, and 7038 (2803/4235) and 963 patients to the control group, respectively. No significant difference in opioid prescriptions existed between the groups. However, the chance of being prescribed strong opioids was significantly lower in the intervention group (non-specific back pain: Odds Ratio (OR) 0.735, 95% Confidential Interval (CI) 0.563 to 0.960; specific back pain: OR 0.702, 95% CI 0.577 to 0.852; osteoarthritis: OR 0.644, 95% CI 0.464 to 0.892). The chance of being prescribed weak opioids was significantly higher in patients with specific back pain (OR 1.243, 95% CI 1.032 to 1.497) and osteoarthritis (OR 1.493, 95% CI 1.037 to 2.149) in the intervention group.

CONCLUSION

Coordinated ambulatory healthcare appears to be associated with a lower prescription rate for strong opioids in patients with chronic musculoskeletal disorders.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS00017548).

Prevalence of and factors associated with osteoarthritis and pain in retired Olympians, with comparison to the general population: part 1 – the lower limb

Objectives

This study aims (1) to determine the prevalence of lower limb osteoarthritis (OA) and pain in retired Olympians; (2) to identify factors associated with their occurrence and (3) to compare with a sample of the general population.

Methods

3357 retired Olympians (median 44.7 years) and 1735 general population controls (40.5 years) completed a cross-sectional survey. The survey captured demographics, general health, self-reported physician-diagnosed OA, current joint/region pain and injury history (lasting >1 month). Adjusted OR (aOR) compared retired Olympians with the general population.

Results

The prevalence of (any joint) OA in retired Olympians was 23.2% with the knee most affected (7.4%). Injury was associated with increased odds (aOR, 95% CI) of OA and pain in retired Olympians at the knee (OA=9.40, 6.90 to 12.79; pain=7.32, 5.77 to 9.28), hip (OA=14.30, 8.25 to 24.79; pain=9.76, 6.39 to 14.93) and ankle (OA=9.90, 5.05 to 19.41; pain=5.99, 3.84 to 9.34). Increasing age and obesity were also associated with knee OA and pain. While the odds of OA did not differ between Olympians and the general population, Olympians with prior knee and prior hip injury were more likely than controls with prior injury to experience knee (1.51, 1.03 to 2.21 (Olympians 22.0% vs controls 14.5%)) and hip OA (4.03, 1.10 to 14.85 (Olympians 19.1% vs Controls 11.5%)), respectively.

Conclusions

One in four retired Olympians reported physician-diagnosed OA, with injury associated with knee, hip and ankle OA and pain. Although overall OA odds did not differ, after adjustment for recognised risk factors Olympians were more likely to have knee and hip OA after injury than the general population, suggesting injury is an occupational risk factor for retired Olympians.

Evaluation of a collaborative ambulatory orthopedic care program for patients with hip and knee osteoarthritis: a comparative observational cohort study

BACKGROUND

In 2014, the novel orthopedic care program was established by the AOK health insurance fund in southern Germany to improve ambulatory care for patients with musculoskeletal disorders. The program offers extended consultation times, structured collaboration between general practitioners and specialists, as well as a renewed focus on guideline-recommended therapies and patient empowerment. The aim of this study was to assess the impact of the program on health service utilization in patients with hip and knee osteoarthritis (OA).

METHODS

This retrospective cohort study, which is based on claims data, evaluated health service utilization in patients with hip and knee OA from 2014 to 2017. The intervention group comprised OA patients enrolled in collaborative ambulatory orthopedic care, and the control group received usual care. The outcomes were participation in exercise interventions, prescription of physical therapy, OA-related hospitalization, and endoprosthetic surgery rates. Generalized linear regression models were used to analyze the effect of the intervention.

RESULTS

Claims data for 24,170 patients were analyzed. Data for the 23,042 patients in the intervention group were compared with data for the 1,128 patients in the control group. Participation in exercise interventions (Odds Ratio (OR): 1.781; 95% Confidence Interval (CI): 1.230-2.577; p = 0.0022), and overall prescriptions of physical therapy (Rate Ratio (RR): 1.126; 95% CI: 1.025-1.236; p = 0.0128) were significantly higher in the intervention group. The intervention group had a significantly lower risk of OA -related hospitalization (OR: 0.375; 95% CI: 0.290-0.485; p < 0.0001). Endoprosthetic surgery of the knee was performed in 53.8% of hospitalized patients in the intervention group vs. 57.5% in the control group; 27.7% of hospitalized patients underwent endoprosthetic surgery of the hip in the intervention group versus 37.0% in the control group.

CONCLUSIONS

In patients with hip and knee OA, collaborative ambulatory orthopedic care is associated with a lower risk of OA-related hospitalization, higher participation in exercise interventions, and more frequently prescribed physical therapy.

Intra-articular Hymovis injection for managing hip OA in active sportsmen. A 24-month observational retrospective clinical investigation

BACKGROUND

Hip Osteoarthitis (OA) risk is sport-specific and depends on frequency, intensity, and type of mechanic stress the hip is subjected to. This retrospective observational study aims to investigate the safety and performance of Hymovis (HYADD-4) injection, a hexadecyl (C-16) HA-derivative, when used to manage symptomatic hip OA in active middle-aged sportsmen over a 24-month observation period.

METHODS

The retrospective analysis included clinical records of active sportsmen, aged between 40 and 65 years, and suffering from symptomatic Kellgren-Lawrence grade II to III hip OA, treated with two (24 mg/3 ml) Hymovis injections, two weeks apart, every 3-4 months, for two years. When available, data on MRI examination were included in the analysis as well as Heidelberg Sports Activity Score (HAS) and Copenhagen Hip and Groin Outcome Score (HAGOS) questionnaires.

RESULTS

Thirty patients (56.4 ± 7.3 years) were included in the study, sixteen cyclists and 14 tennis players. For all patients, HAS and most HAGOS scores improved significantly (p < 0.05) at the first control visit (4 months) and further improved over time. For all other scores an important clinical benefit was experienced by more than 50% of participants. No adverse events were recorded.

CONCLUSION

Treatment of hip OA in active sportsmen with Hymovis seems a safe and effective approach for the management of OA symptoms, by potentially protecting cartilage and subchondral bone from further damage.

Effects of the Obesity Epidemic on Total Hip and Knee Arthroplasty Demographics

BACKGROUND

Higher body mass index (BMI) is a well-known risk factor for the development of hip and knee osteoarthritis and predicts total hip arthroplasty (THA) and total knee arthroplasty (TKA) at an earlier age. The purpose of this study is to document the nationwide trends in age and obesity in primary THA and TKA throughout the obesity epidemic.

METHODS

A retrospective analysis of the National Inpatient Sample database was conducted on patients undergoing primary THA and TKA for primary OA between 2002 and 2017. Analysis of variance and chi-square tests were performed to examine changes in age and obesity percentage over time, respectively. Pearson correlations were used to assess the relationship between patient age, BMI, and year of surgery.

RESULTS

A total of 688,371 THA and 1,556,651 TKA were identified over the sixteen-year period. Between 2002 and 2017, the proportion of obese patients increased for both THA (7.0% to 22.7%, P < .001) and TKA (10.7% to 30.4%, P < .001). Mean age significantly decreased for both THA (66.7 to 65.9 years, P < .001) and TKA (67.6 to 66.8 years; P < .001). Over time, BMI significantly increased (THA: r = 0.221 vs. TKA: r = 0.272) and patient age decreased (THA: r = -0.031 vs. TKA: r = -0.137) for both procedures (P < .001 for all).

CONCLUSION

THA and TKA patients have become younger and increasingly more obese throughout the obesity epidemic, as obesity rates have tripled over this time period. The current investigation is the first to demonstrate significant trends in both age and obesity in the THA and TKA populations on a national level.

LEVEL OF EVIDENCE

III.

Epidemiological study of post-traumatic ankle osteoarthritis after ankle sprain in 195,393 individuals over middle age using the National Health Insurance Database: A retrospective design

OBJECTIVES

This study aimed to determine the risk of ankle OA onset after an incidence of sprain, relative to the risk of onset in healthy population, and to investigate the effect of gender, age, BMI, and exercise on the development of ankle OA after sprain.

DESIGN

Retrospective cohort study.

METHODS

Using a sample cohort dataset from 2002 to 2013 provided by the Korean National Health Insurance Sharing Service, we calculated the mean survival time and cumulative incidence rate in sprained and healthy populations using Kaplan-Meier analysis. A Cox proportional hazards model was used to analyze the adjusted hazard ratio (HR) of sprain for the development of OA with 95% confidence intervals (CIs). Adjusted HRs of gender, age, BMI, and exercise (yes/no) were analyzed in the sprained group.

RESULTS

Among the selected population of 195,393 individuals, 40,876 (20.9%) were diagnosed with an ankle sprain, and 1543 (3.85%) of those individuals developed ankle OA. Of the 154,517 healthy individuals (79.1%), 4062 (2.66%) cases had progressed to OA. The sprained group had 46% (HR, 1.46; 95% CI, 1.38-1.55) greater rate of progression to ankle OA than did healthy individuals. In the sprain group, individuals who were female, obese, and overweight had 40% (HR, 1.40; 95% CI, 1.26-1.55), 43% (HR, 1.43; 95% CI, 1.12-1.82), and 22% (HR, 1.22; 95% CI, 1.10-1.35) higher incidence to develop ankle OA, respectively, compared to those who were male, underweight and normal.

CONCLUSIONS

This study found that ankle sprain was a significant risk factor for a diagnosis of early OA. Female gender and high BMI increased the incidence of ankle OA after sprain.

Exercise as Medicine During the Course of Hip Osteoarthritis

Exercise is now considered medicine in numerous chronic conditions and is essentially without side effects. We hypothesize that exercise is primary, secondary, and tertiary prevention at different stages of hip osteoarthritis (preclinical, mild-moderate, and severe hip osteoarthritis) and after total hip arthroplasty.

The association between alcohol consumption and osteoarthritis: a meta-analysis and meta-regression of observational studies

There is conflicting evidence for the association between alcohol consumption and common joint conditions such as Osteoarthritis (OA), which affects millions of people. We sought to determine the true association between alcohol intake and OA. We conducted a PRISMA systematic review and meta-analysis of observational studies that reported associations between alcohol consumption and OA. Pooled estimates of association were represented through odds ratios (ORs). Publication bias was assessed with Funnel and Galbraith plots, and risk of bias was assessed with the Newcastle Ottawa Scale. We included 29 studies and 25,192 subjects with OA and reported an OR between any alcohol consumption and OA of 0.79 (0.68–0.93), suggesting a protective effect. OR of weekly or more frequent use was 0.79 (0.65–0.97). When grouped by covariates, alcohol consumption was negatively associated with radiographic (0.83, 0.70–0.98), hand (0.80, 0.66–0.95) and knee OA (0.85, 0.72–0.99), North American ethnicity and female gender. Subgroup analysis of unadjusted data resulted in an OR of 0.70 (0.55–0.89) but this disappeared upon analysis of studies with data adjusted for any covariate (0.93, 0.78–1.10). Whilst our pooled analysis suggest that weekly or more frequent alcohol consumption was negatively associated with OA, this was not observed when adjusted for confounding factors. Reasons for this include selection bias and lack of longitudinal exposure and adjustment for confounding variables. Therefore, this meta-analysis provides evidence to dispel notions that alcohol use may be protective against OA.

The relationship between alcohol consumption and knee osteoarthritis in Korean population over 50 years-old: Results from Korea National Health and Nutrition Examination Survey

ABSTRACT

There is still debate regarding the pathogenic relationship between alcohol intake and osteoarthritis (OA). This study investigated the association between alcohol consumption and knee OA in a Korean population.Among 8058 subjects who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) 2012, a total of 2917 subjects over the age of 50 and taken plain radiography was included in this analysis. Knee OA was classified based on the Kellgren-Lawrence (K-L) grading scale. Multivariate logistic regression analyses were used to evaluate the odds ratios (ORs) and 95% confidence intervals (CIs) of variables for knee OA (K-L grade ≥ 2).There were 1022 subjects with knee OA (29.2%). Subjects with knee OA tended to have lower daily alcohol intake (g/day) than did those without knee OA (10.4 [6.2-14.6] vs. 15.8 [12.8-18.8], P = .04). Similarly, those with knee OA demonstrated less makgeolli intake than did those without knee OA (P = .002). Subjects who consumed >0.6 g/day of beer also demonstrated less knee OA than did those who consumed <0.6 g/day of beer (OR 0.68, 95% CI 0.46-0.99). However, knee OA was not associated with the categories of alcohol consumption amount (g/day), including total daily alcohol intake (g/day), soju daily intake (g/day), and makgeolli daily intake (g/day) (P > .05 of all).Alcohol consumption was negatively associated with prevalence of knee OA in a Korean population. This preliminary observation will need to be confirmed in future studies.

Development of a prognostic prediction model to estimate the risk of multiple chronic diseases: constructing a copula-based model using Canadian primary care electronic medical record data

Introduction

The ability to estimate risk of multimorbidity will provide valuable information to patients and primary care practitioners in their preventative efforts. Current methods for prognostic prediction modelling are insufficient for the estimation of risk for multiple outcomes, as they do not properly capture the dependence that exists between outcomes.

Objectives

We developed a multivariate prognostic prediction model for the 5-year risk of diabetes, hypertension, and osteoarthritis that quantifies and accounts for the dependence between each disease using a copula-based model.

Methods

We used data from the Canadian Primary Care Sentinel Surveillance Network (CPCSSN) from 2009 onwards, a collection of electronic medical records submitted by participating primary care practitioners across Canada. We identified patients 18 years and older without all three outcome diseases and observed any incident diabetes, osteoarthritis, or hypertension within 5-years, resulting in a large retrospective cohort for model development and internal validation (n=425,228). First, we quantified the dependence between outcomes using unadjusted and adjusted Ø coefficients. We then estimated a copula-based model to quantify the non-linear dependence between outcomes that can be used to derive risk estimates for each outcome, accounting for the observed dependence. Copula-based models are defined by univariate models for each outcome and a dependence function, specified by the parameter θ. Logistic regression was used for the univariate models and the Frank copula was selected as the dependence function.

Results

All outcome pairs demonstrated statistically significant dependence that was reduced after adjusting for covariates. The copula-based model yielded statistically significant θ parameters in agreement with the adjusted and unadjusted Ø coefficients. Our copula-based model can effectively be used to estimate trivariate probabilities.

Discussion

Quantitative estimates of multimorbidity risk inform discussions between patients and their primary care practitioners around prevention in an effort to reduce the incidence of multimorbidity.

Kinetic gait analysis in healthy dogs and dogs with osteoarthritis: An evaluation of precision and overlap performance of a pressure-sensitive walkway and the use of symmetry indices

In veterinary practice, a thorough gait examination is essential in the clinical workup of any orthopedic patient, including the large population of dogs with chronic pain as a result of osteoarthritis. The traditional visual gait examination is, however, a subjective discipline, and systems for kinetic gait analysis may potentially offer an objective alternative for gait assessment by the measurement of ground reaction forces. In order to avoid unnecessary testing of patients, a thorough, stepwise evaluation of the diagnostic performance of each system is recommended before clinical use for diagnostic purposes. The aim of the study was to evaluate the Tekscan pressure-sensitive walkway system by assessing precision (agreement between repetitive measurements in individual dogs) and overlap performance (the ability to distinguish dogs with lameness due to osteoarthritis from clinically healthy dogs). Direction of travel over the walkway was investigated as a possible bias. Symmetry indices are commonly used to assess lameness by comparing ground reaction forces across different combinations of limbs in each dog. However, SIs can be calculated in several different ways and specific recommendations for optimal use of individual indices are currently lacking. Therefore the present study also compared indices in order to recommend a specific index preferable for future studies of canine osteoarthritis. Forty-one clinically healthy dogs and 21 dogs with osteoarthritis were included in the study. High precision was demonstrated. The direction of travel over the walkway was excluded as a possible bias. A significant overlap was observed when comparing ground reaction forces measured in dogs with osteoarthritis compared to clinically healthy dogs. In some affected dogs, symmetry indices comparing contralateral limbs differed from clinically healthy dogs, but in general, the overlap performance was insufficient and, consequently, general use of this method for diagnostic purposes in dogs with osteoarthritis cannot be recommended.

To what extent is severe osteoarthritis preventable? Occupational and non-occupational risk factors for knee and hip osteoarthritis

OBJECTIVES

To explore the relative contribution of cumulative physical workload, sociodemographic and lifestyle factors, as well as prior injury to hospitalization due to knee and hip OA.

METHODS

We examined a nationally representative sample of persons aged 30-59 years, who participated in a comprehensive health examination (the Health 2000 Study). A total of 4642 participants were followed from mid-2000 to end-2015 for the first hospitalization due to knee or hip OA using the National Hospital Discharge Register. We examined the association of possible risk factors with the outcome using a competing risk regression model (death was treated as competing risk) and calculated population attributable fractions for statistically significant risk factors.

RESULTS

Baseline age and BMI as well as injury were associated with the risk of first hospitalization due to knee and hip OA. Composite cumulative workload was associated with a dose-response pattern with hospitalizations due to knee OA and with hospitalizations due to hip OA at a younger age only. Altogether, prior injury, high BMI and intermediate to high composite cumulative workload accounted for 70% of hospitalizations due to knee OA. High BMI alone accounted for 61% and prior injury only for 6% of hospitalizations due to hip OA.

CONCLUSION

Our results suggest that overweight/obesity, prior injury and cumulative physical workload are the most important modifiable risk factors that need to be targeted in the prevention of knee OA leading to hospitalization. A substantial proportion of hospitalizations due to hip OA can be reduced by controlling excess body weight.

A comparison of risk factors for osteo- and rheumatoid arthritis using NHANES data

•

Both osteo- and rheumatoid arthritis increase with age.

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Osteoarthritis is more common in whites, but rheumatoid arthritis is in blacks.

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Obesity and female sex increase risk of risk of both osteo- and rheumatoid arthritis.

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Smoking increases risk of both forms of arthritis in women.

•

These two forms of arthritis have many common risk factors.

Osteoarthritis and rheumatoid arthritis are both diseases of joints, but they have very different etiologies. Osteoarthritis is a disease assumed to result from wear and tear over time, whereas rheumatoid arthritis is an autoimmune disease where the body’s immune system attacks joint tissues. Using NHANES data (1999–2015), we have compared the influence of age, sex, ethnicity, body mass index and smoking on these two very different forms of arthritis. Incidence of both increases with age and are more frequent in females than males. There is little apparent difference between osteoarthritis and rheumatoid arthritis in women of normal as comparted to overweight, but both are more frequent in obese women, especially those over the age of 60. While osteoarthritis is more frequent in whites, blacks have more rheumatoid arthritis, and Hispanics show an intermediate prevalence. Smoking significantly increased the incidence of both osteoarthritis and rheumatoid arthritis in women, but increased prevalence of only RA in men. There was no effect of smoking on OA prevalence in males. It is remarkable that two diseases of joints, which have quite different causes, should have so many commonalities. The differences that exist appear to be due to a combination of inflammatory markers and access to health care.

The effects of obesity on the human body, part I: Skin and musculoskeletal

Obesity is a worldwide issue that many global health authorities consider a growing epidemic. Having a positive correlation between increases in the industrialization of processed foods and sedentary occupations as well as a lack of access to healthcare in poorer socioeconomic areas, obesity is a multifactorial disease affecting several organ systems. The tendency for obesity to cause detrimental changes to the human body is a focal point for healthcare providers to establish more effective clinical treatment and management plans. Implementing comprehensive global educational programs to decrease the prevalence of this unforgiving disease is imperative for a healthier future. Herein, we have provided a comprehensive review of the health effects of obesity upon the human body for the interest of many practicing clinicians managing this health crisis.

Impact of smoking on femorotibial and hip osteoarthritis progression: 3-year follow-up data from the KHOALA cohort

OBJECTIVES

To evaluate the clinical and structural impact of smoking on knee and hip osteoarthritis at baseline and after 3years.

METHODS

Observational data on the progressive effects of smoking at baseline and after 3years were collected from The Knee and Hip Osteoarthritis Long-Term Assessment cohort comprising a French population of patients aged 40-75years with symptomatic lower limb osteoarthritis. Clinical (the Western Ontario and McMaster Universities Arthritis Index and Harris scores) and structural (radiography for osteophyte detection and joint-space narrowing assessment) were conducted. The tobacco usage categories were 'never smoker', 'former smoker', and 'current smoker'.

RESULTS

Of the 873 subjects included, 215 (25%) were former smokers and 119 (14%) were current smokers. Multivariate analyses revealed that former and current smokers had fewer knee osteophytes in the medial compartment at baseline (odds ratio [OR]=0.64 [0.41-0.99] and 0.63 [0.36-1.11], respectively), lower osteophyte development in the lateral condyle after 3years (OR=011 [0.03-0.45] and 0.15 [0.03-0.97]), and lower osteophyte development in the lateral tibial plateau after 3years (OR=0.22 [0.06-0.75] and 0.68 [0.14-3.35]). Higher tobacco consumption and longer duration of consumption were significantly associated with fewer knee osteophytes at baseline and lower osteophyte development at 3years.

CONCLUSION

Although cigarette smoking did not influence knee function, pain, or the need for replacement surgery, current and former smokers developed fewer osteophytes. This relationship may be linked to the quantity and duration of consumption. Our results provide further insight into the smoking-related pathophysiology of osteoarthritis.

Effect of body mass on future long-term care use

BACKGROUND

Obesity is a known predictor of disability and functional limitations, and, in turn, of health care use. In this study, we aim to explore whether obesity is also a significant risk factor for future long-term care use, overall and by type of care.

METHODS

We use multinomial logistic regression analysis on data from the English Longitudinal Study of Ageing (ELSA) for individuals aged 65 and older between 2002 and 2011. Selection issues are tackled using the rich set of control variables, exploiting the data's longitudinal structure and accounting for loss to follow-up (including death). Control factors include health-related behaviours (physical activity, alcohol and tobacco consumption), functional limitations (related to ADLs, iADLs and mobility) and specific existing health conditions, notably diabetes, high blood pressure and cardio-vascular diseases.

RESULTS

We find that obese older people are 25% (p < 0.01) more likely to receive informal or privately-paid care in the future, but this does not hold for formal care. This is an additional direct effect after controlling for a wide range of health conditions and functional limitations. We document some evidence that this effect is due to the development of new functional limitations. Sensitivity analyses suggest that the results are robust to controlling for prediabetes, subjective health, depression, or unobserved heterogeneity.

CONCLUSIONS

This study provides new evidence of a positive direct effect of obesity on the future use of long-term care services. Accordingly, it adds evidence of further economic benefits to any overall evaluation of policies to promote a healthy weight in the population, particularly in the older population.

Development and evaluation of an osteoarthritis risk model for integration into primary care health information technology

BACKGROUND

We developed and evaluated a prognostic prediction model that estimates osteoarthritis risk for use by patients and practitioners that is designed to be appropriate for integration into primary care health information technology systems. Osteoarthritis, a joint disorder characterized by pain and stiffness, causes significant morbidity among older Canadians. Because our prognostic prediction model for osteoarthritis risk uses data that are readily available in primary care settings, it supports targeting of interventions delivered as part of clinical practice that are aimed at risk reduction.

METHODS

We used the CPCSSN (Canadian Primary Sentinel Surveillance Network) database, which contains aggregated electronic health information from a cohort of primary care practices, to develop and evaluate a prognostic prediction model to estimate 5-year osteoarthritis risk, addressing contextual challenges of data availability and missingness. We constructed a retrospective cohort of 383,117 eligible primary care patients who were included in the cohort if they had an encounter with their primary care practitioner between 1 January 2009 and 31 December 2010. Patients were excluded if they had a diagnosis of osteoarthritis prior to their first visit in this time period. Incident cases of osteoarthritis were observed. The model was constructed to predict incident osteoarthritis based on age, sex, BMI, previous leg injury, and osteoporosis. Evaluation of the model used internal 10-fold cross-validation; we argue that internal validation is particularly appropriate for a model that is to be integrated into the same context from which the data were derived.

RESULTS

The resulting prediction model for 5-year risk of osteoarthritis diagnosis demonstrated state-of-the-art discrimination (estimated AUROC 0.84) and good calibration (assessed visually.) The model relies only on information that is readily available in Canadian primary care settings, and hence is appropriate for integration into Canadian primary care health information technology.

CONCLUSIONS

If the contextual challenges arising when using primary care electronic medical record data are appropriately addressed, highly discriminative models for osteoarthritis risk may be constructed using only data commonly available in primary care. Because the models are constructed from data in the same setting where the model is to be applied, internal validation provides strong evidence that the resulting model will perform well in its intended application.

Post-traumatic osteoarthritis diagnosed within 5 years following ACL reconstruction

PURPOSE

The purpose was to calculate the incidence of osteoarthritis in individuals following Anterior Cruciate Ligament Reconstruction (ACLR) in a large, national database and to examine the risk factors associated with OA development.

METHODS

A commercially available insurance database was queried to identify new diagnoses of knee OA in patients with ACLR. The cumulative incidence of knee OA diagnoses in patients after ACLR was calculated and stratified by time from reconstruction. Odds ratios were calculated using logistic regression to describe factors associated with a new OA diagnosis including age, sex, BMI, meniscus involvement, osteochondral graft use, and tobacco use.

RESULTS

A total of 10,565 patients with ACLR were identified that did not have an existing diagnosis of OA, 517 of which had a documented new diagnosis of knee OA 5 years after ACL reconstruction. When stratified by follow-up time points, the incidence of a new OA diagnosis within 6 months was 2.3%; within a 1-year follow-up was 4.1%; within 2 years, follow-up was 6.2%, within 3 years, follow-up was 8.4%; within 4 years, follow-up was 10.4%; and within 5 years, follow-up was 12.3%. Risk factors for new OA diagnoses were age (OR 2.44, P < 0.001), sex (OR 1.2, P = 0.002), obesity (OR 1.4, P < 0.001), tobacco use (OR = 1.3, P = 0.001), and meniscal involvement (OR 1.2, P = 0.005).

CONCLUSION

Approximately 12% of patients presenting within 5 years following ACLR are diagnosed with OA. Demographic factors associated with an increased risk of a diagnosis of PTOA within 5 years after ACLR are age, sex, BMI, tobacco use, and concomitant meniscal surgery. Clinicians should be cognizant of these risk factors to develop risk profiles in patients with the common goal to achieve optimal long-term outcomes after ACLR.

LEVEL OF EVIDENCE

III.

Household air pollution and arthritis in low-and middle-income countries: Cross-sectional evidence from the World Health Organization's study on Global Ageing and Adult Health

Background

Evidence points to a clear link between air pollution exposure and several chronic diseases though investigations regarding arthritis are still lacking. Emerging evidence suggests an association between ambient air pollution and rheumatoid arthritis. Household air pollution exposure, conversely, is largely unstudied but may be an important consideration for arthritis, particularly in low- and middle-income countries (LMICs), where cooking and heating activities can generate high indoor air pollutant levels.

Methods

We investigated the association of household air pollution (electricity vs. gas; kerosene/paraffin; coal/charcoal; wood; or agriculture/crop/animal dung/shrubs/grass as the main fuel used for cooking) and arthritis in six LMICs (China, Ghana, India, Mexico, the Russian Federation, South Africa) using data from Wave I of the World Health Organization Study on Global AGEing and Adult Health (SAGE) (2007–2010). Multivariable analyses were adjusted for sociodemographic, household and lifestyle characteristics and several comorbidities.

Results

The use of gas (aOR = 1.76, 95%CI: 1.40–2.21); coal (aOR = 1.74, 95%CI: 1.22–2.47); wood (aOR = 1.69, 95%CI: 1.30–2.19); or agriculture/crop/animal dung/shrubs/grass: aOR = 1.95 (1.46–2.61) fuels for cooking were strongly associated with an increased odds of arthritis, compared to electricity in cluster and stratified adjusted analyses. Gender (female), age (≥50 years), overweight (25.0 ≤BMI<30.0 kg/m²), obesity (BMI ≥30.0 kg/m²), former and current alcohol consumption, and the comorbidities angina pectoris, diabetes, chronic lung disease, depression and hypertension were also associated with a higher odds of arthritis. Underweight (BMI<18.5 kg/m²) and higher education levels (college/university completed/post-graduate studies) were associated with a lower odds of arthritis.

Conclusions

These findings suggest that exposure to household air pollution from cook fuels is associated with an increased odds of arthritis in these regions, which warrants further investigation.

Analgesic Herbal Medicines in the Treatment of Knee Osteoarthritis: A Systematic Review

Background:

Osteoarthritis (OA) is a type of progressive rheumatoid disease, which leads to the degeneration of the articular cartilage, synovium, subchondral bone, tendons, and the surrounding ligaments.There are various treatments for knee OA, including pharmaceutical, nonpharmaceutical, and surgical treatments. Considering the chronic nature of the disease as well as the necessity for the long-term use of chemical medications, various side effects could occur that include gastrointestinal bleeding, hypertension, congestive heart failure, hyperkalemia, and kidney failure. Therefore, suitable treatments with fewer side effects should be recommended. Recent investigations suggest increased tendency in people to use Complementary and Alternative Medicine (CAM) for knee OA treatment.

Objective:

This systematic review aimed to assess the effectiveness and safety of herbal preparations for the treatment of OA.

Methods:

The searched databases were Cochrane, Scopus, and PubMed. All the selected papers pertained to randomized controlled trials until August 8, 2017 in English in which one or several specific herbs had been used in knee OA treatment.

Results:

We included 24 randomized trials (involving 2399 women and men). There were several different herbal medicines used within the included trials.

Conclusion:

The results show that the methods used in these trials may reduce symptoms and the extent of NSAID consumption and enhance the quality of life. Additional trials are suggested to investigate the safety and efficacy of herbs for the treatment of patients with OA.

Quantifying the likelihood and costs of hip replacement surgery after sports injury: A population-level analysis

OBJECTIVES

To quantify the likelihood of hip replacement (HR) surgery at a population level up to 15 years after sports injury.

DESIGN

Cohort study.

SETTINGS

Public and private hospitals in the state of Victoria, Australia.

PARTICIPANTS

The cohort was established by linking administrative datasets capturing all hospital admissions and emergency department (ED) presentations. All sports injury presentations from 2000 to 2005 and HR admissions from 2000 to 2015 were identified using ICD-10-AM codes.

MAIN OUTCOME MEASURES

Time to HR (number of days from sports injury admission to HR admission).

RESULTS

Over the study period there were 64,750 sports injuries (including 815 hip or thigh musculoskeletal injuries) that resulted in ED presentation or hospitalisation, and 368 HR procedures. Compared to all other sports injuries, having a hip or thigh injury tripled the hazard of subsequent HR in multivariate analysis (hazard ratio 3.07, 95%CI 2.00-4.72). Of the main hip or thigh injury types, femoral fractures (hazard ratio 3.08, 95%CI 1.77-5.36) and hip dislocations (hazard ratio 5.64, 95%CI 2.34-13.58) were significantly associated with HR.

CONCLUSION

Sports-related hip or thigh musculoskeletal injury is associated with a significantly higher likelihood of HR within 15 years. Effective injury prevention and appropriate post-injury management are needed to curtail this population burden.

Prevalence of and Risk Factors for Total Hip and Knee Replacement in Retired National Football League Athletes

BACKGROUND

Osteoarthritis is a substantial cause of disability. Joint replacement prevalence relates to the burden of severe osteoarthritis, and identifying risk factors for end-stage disease may indicate intervention opportunities. American football has high youth and elite participation, and determining risk factors for severe osteoarthritis may support future morbidity prevention.

PURPOSE

To (1) determine the prevalence of hip and knee replacement in retired National Football League (NFL) athletes, (2) examine risk factors for replacement, and (3) identify the association between knee injuries and knee replacement.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Retired NFL athletes who participated in a general health survey were included. This historical cohort included those playing between 1929 and 2001. The association between self-reported playing or injury history, and replacement after retirement, was assessed with prevalence ratios (PRs). Models were adjusted for potential confounders of age and weight.

RESULTS

Data for 2432 retired male NFL players (69.3% response rate) who had participated in football for a mean 15.2 years were included, in which 277 players reported replacement after retirement (11.4%). More participants reported knee replacement (7.7%) than hip replacement (4.6%). The majority of participants reported previous severe knee injury (53%), and the most prevalent was meniscal tear (32.2%). In multivariable models, age (10-year increase, PR, 2.23; 95% CI, 1.99-2.51), current weight (PR, 1.10; 95% CI, 1.06-1.14), and reporting 1 (PR, 1.78; 95% CI, 1.14-2.77), 2 (PR, 1.91; 95% CI, 1.16-3.15), or ≥3 knee injuries (PR, 3.44; 95% CI, 2.33-5.09) were associated with knee replacement. Age (10-year increase, PR, 1.86; 95% CI, 1.59-2.18), linemen (PR, 1.62; 95% CI, 1.03-2.55), and reporting 1 (PR, 1.72; 95% CI, 1.05-2.80), 2 (PR, 2.77 95% CI, 1.58-4.84), or ≥3 (PR, 2.44; 95% CI, 1.52-3.91) hip injuries were associated with hip replacement. Each reported knee injury type was cross-sectionally associated with replacement after retirement (P < .05).

CONCLUSION

Knee replacement was more prevalent than hip replacement. Risk factors differed between the hip and the knee, with age and severe joint injury associated with hip and knee replacement, weight with knee replacement, and playing position associated with hip replacement. Joint injury and weight management may be prevention opportunities to reduce morbidity and end-stage osteoarthritis in this population.

Muscle recruitment strategies can reduce joint loading during level walking

Joint inflammation, with consequent cartilage damage and pain, typically reduces functionality and affects activities of daily life in a variety of musculoskeletal diseases. Since mechanical loading is an important determinant of the disease process, a possible conservative treatment is the unloading of joints. In principle, a neuromuscular rehabilitation program aimed to promote alternative muscle recruitments could reduce the loads on the lower-limb joints during walking. The extent of joint load reduction one could expect from this approach remains unknown. Furthermore, assuming significant reductions of the load on the affected joint can be achieved, it is unclear whether, and to what extent, the other joints will be overloaded. Using subject-specific musculoskeletal models of four different participants, we computed the muscle recruitment strategies that minimised the hip, knee and ankle contact force, and predicted the contact forces such strategies induced at the other joints. Significant reductions of the peak force and impulse at the knee and hip were obtained, while only a minimal effect was found at the ankle joint. Adversely, the peak force and the impulse in non-targeted joints increased when aiming to minimize the load in an adjacent joint. These results confirm the potential of alternative muscle recruitment strategies to reduce the loading at the knee and the hip, but not at the ankle. Therefore, neuromuscular rehabilitation can be targeted to reduce the loading at affected joints but must be considered carefully in patients with multiple joints affected due to the potential adverse effects in non-targeted joints.

The Complex Interactions Between Obesity, Metabolism and the Brain

Obesity is increasing at unprecedented levels globally, and the overall impact of obesity on the various organ systems of the body is only beginning to be fully appreciated. Because of the myriad of direct and indirect effects of obesity causing dysfunction of multiple tissues and organs, it is likely that there will be heterogeneity in the presentation of obesity effects in any given population. Taken together, these realities make it increasingly difficult to understand the complex interplay between obesity effects on different organs, including the brain. The focus of this review is to provide a comprehensive view of metabolic disturbances present in obesity, their direct and indirect effects on the different organ systems of the body, and to discuss the interaction of these effects in the context of brain aging and the development of neurodegenerative diseases.

Health Care Providers' Advice on Lifestyle Modification in the US Population: Results from the NHANES 2011-2016

OBJECTIVE

Health care providers are encouraged to prescribe lifestyle modifications for preventing and managing obesity and associated chronic conditions. However, the pattern of lifestyle advice provision is unknown. We investigate the prevalence of advised lifestyle modification according to weight status and chronic conditions in a US nationally representative sample.

METHODS

Adults ages 20-64years (n = 11,467) from the National Health and Nutrition Examination Survey between 2011 and 2016 were analyzed, with weight status and chronic conditions (high blood pressure, high blood cholesterol, osteoarthritis, coronary heart disease, and type 2 diabetes mellitus). Lifestyle modification advice by health care providers included: increase physical activity/exercise, reduce dietary fat/calories, control/lose weight, and all of the above.

RESULTS

High blood pressure (32.7%) and cholesterol (29.3%) were highly prevalent compared with osteoarthritis (7.4%), type 2 diabetes (5.7%), and coronary heart disease (3.7%). Those with type 2 diabetes received considerably more frequent advice (56.5%; 95% confidence interval [CI], 52.4%-60.6%) than those with high blood pressure (31.4%; 95% CI, 29.3%-33.6%) and cholesterol (27.0%; 95% CI, 24.9%-29.3%). Prevalence of lifestyle advice exhibited substantial increases with graded body mass index and comorbidity (all P < .001). After adjusting for comorbid conditions, advice was more commonly reported among women, those overweight/obese, nonwhite, or insured. A remarkably low proportion of overweight (21.4; 95% CI, 18.7%-24.3%) and obese (44.2%; 95% CI, 41.0%-47.4%) adults free of chronic conditions reported receiving any lifestyle advice.

CONCLUSIONS

Prevalence of lifestyle modification advised by health care providers is generally low among US adults with chronic conditions, and worryingly low among those without chronic conditions, however overweight or obese. Prescribed lifestyle modification is a missing opportunity in implementing sustainable strategies to reduce chronic condition burden.

A Possible New Radiographic Predictor of Progression of Osteoarthritis in Developmental Dysplasia of the Hip: The Center Gap

BACKGROUND

Patients with comparable severities of developmental dysplasia of the hip (DDH) may variably progress to osteoarthritis (OA) over time. Although joint congruency may be associated with OA progression in patients with DDH, it has only been assessed subjectively. We assessed the gap between the rotational centers of the acetabulum and femoral head (center gap) as a possible predictive measure of OA progression in patients with DDH.

QUESTIONS/PURPOSES

In patients with bilateral DDH, we asked: (1) What is the probability of OA progression (Tönnis grade) or symptom development (pain) in the asymptomatic contralateral hip of patients with DDH undergoing unilateral joint-preserving surgery? (2) Is the center gap measurement associated with OA progression or symptom development in these hips? (3) Is the center gap measurement correlated with previous radiographic parameters?

METHODS

A total of 297 patients (319 hips) underwent unilateral eccentric rotational acetabular osteotomy at our institution between July 1989 and December 1999. We performed no other joint-preserving surgery to treat patients with DDH during this timeframe. The inclusion criteria for the study were patients younger than 55 years of age, the contralateral hip classified as Tönnis Grade 0, no previous surgical interventions, and asymptomatic at the time of eccentric rotational acetabular osteotomy (155 patients, 155 hips). The exclusion criteria were a contralateral hip without dysplasia (four patients, four hips), loss to followup before 10 years (42 patients, 42 hips [27%]), or missing medical records or radiographs (21 patients, 21 hips [14%]). The remaining 88 patients (88 hips; 11 males and 77 females) with a mean age of 39 years (range, 17-53 years) and mean followup of 20 years (range, 10-27 years) were analyzed. From the institutional database, radiographic parameters including the center gap in the AP view were assessed using radiographs at the time of eccentric rotational acetabular osteotomy, and the Tönnis grade was recorded 1 year postoperatively and annually thereafter retrospectively. We defined migration of the rotational center of the femoral head based on the rotational center of the acetabulum in the horizontal plane as center gap X (mm) and in the vertical plane as center gap Y (mm) and defined the absolute value between the centers as center gap distance (mm). Using κ statistics, intra- and interobserver reliabilities were determined to be 0.896 and 0.857 for center gap X, 0.912 and 0.874 for center gap Y, and 0.912 and 0.901 for the center gap distance, respectively. When patients reported any contralateral ipsilateral hip pain during clinic visits, the hip was considered symptomatic. Kaplan-Meier survivorship analyses were performed with OA progression or symptom development in the nonoperative hip as the endpoint. Multivariate analyses were performed to assess risk factors for each outcome using the Cox proportional hazards model. Correlation analyses between the center gap and other parameters including lateral center-edge angle, femoral head extrusion index, acetabular depth-to-width index, femoral head lateralization, minimum width of the joint space, head sphericity, and joint congruency were performed using Pearson's correlation coefficient.

RESULTS

At 20 years postoperatively, the probability of OA progression in the nonoperative hip was 13% (95% confidence interval [CI], 7.1-22.1) and the probability of symptom development was 34% (95% CI, 24.7-46.1). The center gap X measurements in the groups with OA progression (lateral 2.0 ± 2.1 [SD] mm) or symptom development (lateral 0.9 ± 2.4 mm) took a more lateral direction than those in the group without OA progression (medial 0.4 ± 2.1 mm) or symptom development (medial 0.5 ± 2.0 mm) (OA progression, p < 0.001; symptom development, p = 0.005). The center gap Y measurements in the groups with OA progression (distal 2.7 ± 7.1 mm) or symptom development (distal 2.1 ± 6.0 mm) took a more distal direction than those in the group without OA progression (proximal 1.6 ± 6.2 mm) or symptom development (proximal 2.5 ± 6.1 mm) (OA progression, p = 0.027; symptom development, p = 0.001). Independent risk factors for OA progression were the femoral head extrusion index (hazard ratio [HR], 1.11; 95% CI, 1.01-1.22; p = 0.028) and the center gap X (HR, 1.52; 95% CI, 1.07-2.16; p = 0.019), whereas no independent risk factors for symptom development were found. The center gap in the horizontal plane had no correlations with any other radiographic parameter studied.

CONCLUSIONS

The center gap in the horizontal plane had a modest association with OA progression in this group of patients with DDH. Future studies are needed to determine the normal value of the center gap for patients without DDH and to assess the center gap in lateral radiographic views.

LEVEL OF EVIDENCE

Level IV, prognostic study.

A synthetic polymeric biolubricant imparts chondroprotection in a rat meniscal tear model

Intra-articular injection of hyaluronic acid (HA) is used to treat osteoarthritis (OA) as a viscosupplement, yet it only provides short-term benefit because HA is cleaved by hyaluronidase and cleared out of the joint after several days. Therefore, we developed a new polymer biolubricant based on poly-oxanorbornane carboxylate to enhance joint lubrication for a prolonged time. Rheological and biotribological studies of the biolubricant reveal viscoelastic properties and coefficient of friction equivalent and superior to that of healthy synovial fluid, respectively. Furthermore, in an ex vivo bovine cartilage plug model, the biolubricant exhibits superior long-term reduction of friction and wear prevention compared to saline and healthy synovial fluid. ISO 10993 biocompatibility tests demonstrate that the biolubricant polymer is non-toxic. In an in vivo rat medial meniscal tear OA model, where the performance of the leading HA viscosupplement (Synvisc-one®) is comparable to the saline control, treatment with the biolubricant affords significant chondroprotection compared to the saline control.

Comparative efficacy and safety of oral or transdermal opioids in the treatment of knee or hip osteoarthritis: a systematic review and Bayesian network meta-analysis protocol

INTRODUCTION

Osteoarthritis is a common degenerative joint disease that eventually leads to disability and poor quality of life. The main symptoms are joint pain and mobility disorders. If the patient has severe pain or other analgesics are contraindicated, opioids may be a viable treatment option. To evaluate and compare the efficacy and safety of opioids in the treatment of knee or hip osteoarthritis, we will integrate direct and indirect evidence using a Bayesian network meta-analysis to establish hierarchies of these drugs.

METHODS AND ANALYSIS

We will search the Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, Web of Science and PsycINFO databases as well as published and unpublished research in international registries and regulatory agency websites for osteoarthritis reports published prior to 5 January 2018. There will be no restrictions on the language. Randomised clinical trials that compare oral or transdermal opioids with other various opioids, placebo or no treatment for patients with knee or hip osteoarthritis will be included. The primary outcomes of efficacy will be pain and function. We will use pain and function scales to evaluate the main outcomes. The secondary outcomes of safety will be defined as the proportion of patients who have stopped treatment due to side effects. Pairwise meta-analyses and Bayesian network meta-analyses will be performed for all related outcome measures. We will conduct subgroup analyses and sensitivity analyses to assess the robustness of our findings. The Grading of Recommendations, Assessment, Development and Evaluations framework will be used to assess the quality of the evidence contributing to each network assessment.

ETHICS AND DISSEMINATION

This study does not require formal ethical approval because individual patient data will not be included. The findings will be disseminated through peer-reviewed publications or conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42018085503.

Dose-response relationship between cumulative physical workload and osteoarthritis of the hip - a meta-analysis applying an external reference population for exposure assignment

Background

There is consistent evidence from observational studies of an association between occupational lifting and carrying of heavy loads and the diagnosis of hip osteoarthritis. However, due to the heterogeneity of exposure estimates considered in single studies, a dose-response relationship between cumulative physical workload and hip osteoarthritis could not be determined so far.

Methods

This study aimed to analyze the dose-response relationship between cumulative physical workload and hip osteoarthritis by replacing the exposure categories of the included studies with cumulative exposure values of an external reference population. Our meta-regression analysis was based on a recently conducted systematic review (Bergmann A, Bolm-Audorff U, Krone D, Seidler A, Liebers F, Haerting J, Freiberg A, Unverzagt S, Dtsch Arztebl Int 114:581–8, 2017). The main analysis of our meta-regression comprised six case-control studies for men and five for women. The population control subjects of a German multicentre case-control study (Seidler A, Bergmann A, Jäger M, Ellegast R, Ditchen D, Elsner G, Grifka J, Haerting J, Hofmann F, Linhardt O, Luttmann A, Michaelis M, Petereit-Haack G, Schumann B, Bolm-Audorff U, BMC Musculoskelet Disord 10:48, 2009) served as the reference population. Based on the sex-specific cumulative exposure percentiles of the reference population, we assigned exposure values to each category of the included studies using three different cumulative exposure parameters. To estimate the doubling dose (the amount of physical workload to double the risk of hip osteoarthritis) on the basis of all available case-control-studies, meta-regression analyses were conducted based on the linear association between exposure values of the reference population and the logarithm of reported odds ratios (ORs) from the included studies.

Results

In men, the risk to develop hip osteoarthritis was increased by an OR of 1.98 (95% CI 1.20–3.29) per 10,000 tons of weights ≥20 kg handled, 2.08 (95% CI 1.22–3.53) per 10,000 tons handled > 10 times per day and 8.64 (95% CI 1.87–39.91) per 10⁶ operations. These estimations result in doubling dosages of 10,100 tons of weights ≥20 kg handled, 9500 tons ≥20 kg handled > 10 times per day and 321,400 operations of weights ≥20 kg. There was no linear association between manual handling of weights at work and risk to develop hip osteoarthritis in women.

Conclusions

Under specific conditions, the application of an external reference population allows for the derivation of a dose-response relationship despite high exposure heterogeneities in the pooled studies.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2085-8) contains supplementary material, which is available to authorized users.

High-fat/high-sucrose diet-induced obesity results in joint-specific development of osteoarthritis-like degeneration in a rat model

Objectives

Metabolic syndrome and low-grade systemic inflammation are associated with knee osteoarthritis (OA), but the relationships between these factors and OA in other synovial joints are unclear. The aim of this study was to determine if a high-fat/high-sucrose (HFS) diet results in OA-like joint damage in the shoulders, knees, and hips of rats after induction of obesity, and to identify potential joint-specific risks for OA-like changes.

Methods

A total of 16 male Sprague-Dawley rats were allocated to either the diet-induced obesity group (DIO, 40% fat, 45% sucrose, n = 9) or a chow control diet (n = 7) for 12 weeks. At sacrifice, histological assessments of the shoulder, hip, and knee joints were performed. Serum inflammatory mediators and body composition were also evaluated. The total Mankin score for each animal was assessed by adding together the individual Modified Mankin scores across all three joints. Linear regression modelling was conducted to evaluate predictive relationships between serum mediators and total joint damage.

Results

The HFS diet, in the absence of trauma, resulted in increased joint damage in the shoulder and knee joints of rats. Hip joint damage, however, was not significantly affected by DIO, consistent with findings in human studies. The total Mankin score was increased in DIO animals compared with the chow group, and was associated with percentage of body fat. Positive significant predictive relationships for total Mankin score were found between body fat and two serum mediators (interleukin 1 alpha (IL-1α) and vascular endothelial growth factor (VEGF)).

Conclusion

Systemic inflammatory alterations from DIO in this model system may result in a higher risk for development of knee, shoulder, and multi-joint damage with a HFS diet.Cite this article: K. H. Collins, D. A. Hart, R. A. Seerattan, R. A. Reimer, W. Herzog. High-fat/high-sucrose diet-induced obesity results in joint-specific development of osteoarthritis-like degeneration in a rat model. Bone Joint Res 2018;7:274-281. DOI: 10.1302/2046-3758.74.BJR-2017-0201.R2.

Advancing osteochondral tissue engineering: bone morphogenetic protein, transforming growth factor, and fibroblast growth factor signaling drive ordered differentiation of periosteal cells resulting in stable cartilage and bone formation in vivo

Background

Chondrogenic mesenchymal stem cells (MSCs) have not yet been used to address the clinical demands of large osteochondral joint surface defects. In this study, self-assembling tissue intermediates (TIs) derived from human periosteum-derived stem/progenitor cells (hPDCs) were generated and validated for stable cartilage formation in vivo using two different animal models.

Methods

hPDCs were aggregated and cultured in the presence of a novel growth factor (GF) cocktail comprising of transforming growth factor (TGF)-β1, bone morphogenetic protein (BMP)2, growth differentiation factor (GDF)5, BMP6, and fibroblast growth factor (FGF)2. Quantitative polymerase chain reaction (PCR) and immunohistochemistry were used to study in vitro differentiation. Aggregates were then implanted ectopically in nude mice and orthotopically in critical-size osteochondral defects in nude rats and evaluated by microcomputed tomography (µCT) and immunohistochemistry.

Results

Gene expression analysis after 28 days of in vitro culture revealed the expression of early and late chondrogenic markers and a significant upregulation of NOGGIN as compared to human articular chondrocytes (hACs). Histological examination revealed a bilayered structure comprising of chondrocytes at different stages of maturity. Ectopically, TIs generated both bone and mineralized cartilage at 8 weeks after implantation. Osteochondral defects treated with TIs displayed glycosaminoglycan (GAG) production, type-II collagen, and lubricin expression. Immunostaining for human nuclei protein suggested that hPDCs contributed to both subchondral bone and articular cartilage repair.

Conclusion

Our data indicate that in vitro derived osteochondral-like tissues can be generated from hPDCs, which are capable of producing bone and cartilage ectopically and behave orthotopically as osteochondral units.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0787-3) contains supplementary material, which is available to authorized users.

An assessment of the relationship of physical activity, obesity, and chronic diseases/conditions between active/obese and sedentary/ normal weight American women in a national sample

OBJECTIVE

Obesity and physical inactivity are associated with increased rates of chronic diseases and conditions. However, the 'fit but fat' theory posits that cardiopulmonary fitness (or physical activity) can mitigate risks to health associated with obesity. The purpose of this study was to compare chronic diseases and conditions of highly active/obese women with inactive/normal weight women.

STUDY DESIGN

This was a cross-sectional study of the 2015 Behavioral Risk Factor Surveillance System data.

METHODS

Weighted descriptive statistics were performed to describe the demographic characteristics of the two groups. We calculated odds ratios and adjusted odds ratios for chronic diseases and conditions comparing highly active/obese women with inactive/normal weight women.

RESULTS

Highly active/obese women were more likely to report risk factors (hypertension, high cholesterol, and diabetes) for coronary heart disease (CHD) and cardiovascular disease (CVD) than inactive/normal weight women; however, they did not have increased rates of CVD, CHD, or heart attack and had decreased risk for stroke. Highly active/obese women had increased risk for asthma, arthritis, and depression, but not for cancer, kidney disease, or chronic obstructive pulmonary disease.

CONCLUSIONS

Highly active/obese women appear to be staving off the actual development of CHD and CVD; however, further research is needed to understand the long-term health benefits of physical activity among obese women.

Functional Gain and Pain Relief After Total Joint Replacement According to Obesity Status

BACKGROUND

Obesity has been associated with lower function and more pain before and after total hip or knee replacement (THR or TKR). We examined the changes between preoperative and postoperative function and pain in a large representative U.S. cohort to determine if there was a relationship to obesity status.

METHODS

Preoperative and 6-month postoperative data on function (Short Form-36 Physical Component Summary [PCS] score), joint pain (Hip disability and Osteoarthritis Outcome Score and Knee injury and Osteoarthritis Outcome Score), and body mass index (BMI) were collected from a national sample of 2,040 patients who had undergone THR and 2,964 who had undergone TKR from May 2011 to March 2013. Preoperative and postoperative function and pain were evaluated according to BMI status, defined as under or of normal weight, overweight, obese, severely obese, or morbidly obese.

RESULTS

Patients undergoing THR were an average of 65 years of age; 59% were women, 94% were white, and 14% were severely or morbidly obese. A greater obesity level was associated with a lower (worse) PCS score at baseline and 6 months postoperatively. Severely and morbidly obese patients had less postoperative functional gain than the other BMI groups. A greater obesity level was associated with more pain at baseline but greater postoperative pain relief, so the average postoperative pain scores did not differ significantly according to BMI status. Patients undergoing TKR had an average age of 69 years; 61% were women, 93% were white, and 25% were severely or morbidly obese. A greater obesity level was associated with a lower PCS score at baseline and 6 months. The postoperative gain in PCS score did not differ by BMI level. A greater obesity level was associated with worse pain at baseline but greater pain relief at 6 months, so the average pain scores at 6 month were similar across the BMI levels.

CONCLUSIONS

Six months after total joint replacement (TJR), severely or morbidly obese patients reported excellent pain relief and substantial functional gain that was similar to the findings in other patients. While obesity is associated with a greater risk of early complications, obesity in itself should not be a deterrent to undergoing TJR to relieve symptoms.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

The Role of Athletic Trainers in Preventing and Managing Posttraumatic Osteoarthritis in Physically Active Populations: a Consensus Statement of the Athletic Trainers' Osteoarthritis Consortium

OBJECTIVE

  To provide athletic trainers with a fundamental understanding of the pathogenesis and risk factors associated with the development of posttraumatic osteoarthritis (PTOA) as well as the best current recommendations for preventing and managing this condition.

BACKGROUND

  Posttraumatic osteoarthritis, or osteoarthritis that develops secondary to joint injury, accounts for approximately 5.5 million US cases annually. A young athlete with a joint injury is at high risk for PTOA before the age of 40, which could lead to the patient living more than half of his or her life with a painful and disabling disorder. Given our frequent contact with physically active people who often sustain traumatic joint injuries, athletic trainers are in a unique position to help prevent and manage PTOA. We can, therefore, regularly monitor joint health in at-risk patients and implement early therapies as necessary.

RECOMMENDATIONS

  The recommendations for preventing and managing PTOA are based on the best available evidence. Primary injury prevention, self-management strategies, maintenance of a healthy body weight, and an appropriate level of physical activity should be encouraged among those at risk for PTOA after acute traumatic joint injury. Education of athletic trainers and patients regarding PTOA is also critical for effective prevention and management of this disease.

Does metformin protect against osteoarthritis? An electronic health record cohort study

BACKGROUND

Obesity is a major risk factor for osteoarthritis (OA) whilst there is some evidence that diabetes also increases risk. Metformin is a common oral treatment for those with diabetes.

OBJECTIVE

The aim is to investigate whether metformin reduces the risk of OA.

METHODS

This was a cohort study set within the Consultations in Primary Care Archive, with 3217 patients with type 2 diabetes. Patients at 13 general practices with recorded type 2 diabetes in the baseline period (2002-2003) and no prior record of OA were identified. Exposure was a prescription for metformin. Outcome was an OA record during follow up. Cox proportional hazard models with Gamma frailty term were fitted: adjusted for age, gender, deprivation, and comorbidity.

RESULTS

There was no association between prescribed metformin treatment at baseline and OA (adjusted HR: 1.02, 95% CI: 0.91, 1.15). A similar non- significant association was found when allowing exposure status of prescription of metformin to vary over time.