Comparison of 3 supraspinatus tendon repair techniques - a 3D computational finite element analysis

Considering that optimal contact area and pressure at the tendon-bone interface are associated with better footprint repair and outcomes, the aim of this study was to compare the performance of standard double-row, transosseous equivalent (TOE), and partial articular supraspinatus tendon avulsion (PASTA) techniques for the treatment of full-thickness tears of the supraspinatus tendon using 3D finite element models. Loading consisted, alternately, in a preloading of 10 N and 20 N of the sutures. The footprint coverage of the standard double-row, TOE, and PASTA techniques was estimated to represent 19%, 30%, and 35%, respectively, of the repair area. The average contact pressures followed an opposite trend, i.e., the largest was estimated for the standard double-row technique, whereas the lowest was estimated for the PASTA technique. Despite the present study advancing the computational modelling of rotator cuff repair, and the results being consistent with the literature, its findings must be evaluated cautiously, bearing in mind its limitations.

Quantification of Neurospora crassa mitochondrial DNA using quantitative real-time PCR

The filamentous fungus Neurospora crassa is a popular model organism used in a wide range of biochemical and genetic studies and vastly used in mitochondrial research. Despite the relevance of mitochondria in N. crassa biology, no method for quantification of mitochondrial DNA (mtDNA) is currently available. Quantitative real-time PCR (qPCR) is a powerful tool, with a wide range of applications, and has been used for the quantification of nucleic acids in humans and a few other species. Here we present a new qPCR assay for relative quantification of N. crassa mtDNA. Three sets of qPCR primers targeting different regions of the mitochondrial genome were tested for mtDNA quantification. The qPCR was successfully validated in N. crassa strains from different geographical locations, representing the vast genetic diversity of this species, and knockout mutant strains. Moreover the assay proved to be efficient in templates with varied amounts of mitochondria, obtained through different DNA extraction methods. The qPCR performed well in all tested samples revealing a higher amount of mtDNA than nuclear DNA in all cases. This technique will facilitate the characterization of mtDNA of N. crassa in future studies and can be used as a tool to validate methods of mitochondria isolation. SIGNIFICANCE AND IMPACT OF THE STUDY: The standardization of quantitative real-time PCR (qPCR) techniques is essential to enable and facilitate future comparisons. Neurospora crassa is a model organism with a lot of potential in different fields of study. Here we use N. crassa to develop and establish an assay to quantify mitochondrial DNA using qPCR. We tested strains with different geographical background and our data demonstrated the usefulness of this assay to quantify mitochondrial DNA in N. crassa. This technique can be useful in a wide variety of applications and in different types of studies.

Revision after spinal stenosis surgery

PURPOSE

To make a literature review on spinal stenosis recurrence after a first surgery and edit rules to avoid this complication.

METHODS

We conducted two separate PUBMED searches to evaluate the revision post-stenosis and degenerative scoliosis surgery using the terms: lumbar vertebrae/surgery, spinal stenosis, spine, scoliosis and reoperation. The resulting papers were categorized into three groups: (1) those that evaluated reoperation post-simple decompression; (2) those that evaluated spinal decompression and fusion for short (3 levels or less) or long (more than 3 levels) segment spinal fusion; and (3) those diagnosing the stenosis during the surgery.

RESULTS

(1) We found 11 relevant papers that only looked at revision spine surgery post-laminectomy for spinal stenosis. (2) We found 20 papers looked at reoperation post-laminectomy and fusion amongst which there were two papers specifically comparing long-segment (> 3 level) and short-segment (3 or less levels) fusions. (3) In the unspecified group, we found only one article. Fifteen articles were excluded as they were not specifically looking at our objective criteria for revision surgery. In regard to revision post-adult deformity surgery, we found 18 relevant articles.

CONCLUSIONS

After this literature review and analysis of post-operative stenosis, it seems important to provide some advice to avoid revision surgeries more or less induced by the surgery. It looks interesting when performing simple decompression without fusion in the lumbar spine to analyse the risk of instability induced by the decompression and facet resection but also by a global balance analysis. Regarding pre-operative stenosis in a previously operated area, different causes may be evocated, like screw or cage malpositionning but also insufficient decompression which is a common cause. Intraoperatively, the use of neuromonitoring and intraoperative CT scan with navigation are useful tool in complex cases to avoid persisting stenosis. Pre-op analysis and planning are key parameters to decrease post-op problems. These slides can be retrieved under Electronic Supplementary Material.

Vital bleaching for children with dental anomalies: EAPD members' survey

AIM

Understand EAPD members' practices of vital bleaching for children with dental anomalies.

METHODS

An anonymous online survey sent via EAPD in January 2019, consisting of 13 questions with possible multiple answers and free text.

RESULTS

110 responses from 24 countries were obtained. The majority worked in hospitals/universities (n = 69, 63%) or private practices (n = 50, 46%) and were specialists (n = 62, 57%) or senior academics (n = 35, 32%). Most respondents (n = 74 68%) did not provide vital bleaching for children. 88 respondents (80%) belonged to EU: of these, 46 (52%) were not aware of bleaching regulations. For respondents who provided bleaching 26 (72%) undertook home bleaching, using 10% carbamide peroxide (n = 21, 58%), most commonly for 2 weeks (n = 14, 39%), following establishment of the permanent dentition (n = 21, 58%). Deciding factors included: extent (n = 27, 75%) and shade (n = 26, 72%) of discolouration and child being teased by peers (n = 23, 64%). Main reasons for not bleaching included: concerns with side effects (n = 41; 55%) and not agreeing with bleaching (n = 23, 31%). Dentists who did not bleach managed a range of conditions, most frequently molar-incisor hypomineralisation (n = 57; 77%). The majority provided composite restorations with removal of tooth structure (n = 50; 68%) with a number opting for no treatment (n = 27, 37%).

CONCLUSION

This study shows wide variations in treatment of children's dental anomalies across Europe. Fears of adverse effects and personal beliefs seemed to be the main deterrents to bleaching in children. Clinicians who provided bleaching tended to opt for more conservative techniques and to take children's concerns into consideration.

P3399Influence of TCF21 rs12190287 in the coronary artery disease risk prediction. An association study in a Portuguese population

Aim

Investigate the impact of TCF21 rs12190287 in the prediction and discrimination of CAD risk, individually or into a genetic risk score (GRS) formed by a set of 13 genetic variants.

Methods

We performed a case-control study with 3050 subjects (1619 coronary patients with 53.3±8 years; 78.9% male and 1431 controls with 52.8±8 years; 76.6% male) from GENEMACOR study. We investigated all traditional risk factors (TRF), as well as 13 genetic variants from GWAS with unknown pathophysiological pathway so far, including TCF21 (rs12190287), ZC3HC1 (rs11556924), PSRC1/SORTI (rs599839), PHACTR1 (rs1332844), MIA3 (rs17465637), SMAD3 (rs17228212), ZNF259 (rs964184), ADAMTS7 (rs3825807), CDKN2B (rs4977574), 9p21.3 (rs1333049), KIF6 (rs20455), PCSK9 (rs2114580) and GJA4 (rs618675). A multiplicative genetic risk score with these 13 genetic variants (m13GRS), was calculated. Subsequently, two logistic regressions were performed; primarily with all the TRF and all the genes individually and the second with TRF and m13GRS.

Results

The first multivariate analysis shows that, besides the strong association of the TRF with CAD risk (with smoking status on the top of the list, with an OR of 3.2; p<0.0001), TCF21 rs12190287 was the most significant variant from all the studied genetic set with a CAD risk of 1.5 (95% CI: 1.1–1.9; p=0.004), followed by the well-known genetic determinant CDKN2B rs4977574 (OR=1.4; 95% CI: 1.1–1.7; p<0.002) and ZC3HC1 rs11556924 (OR=1.3; 95% CI: 1.0–1.7; p=0.034). When GRS is included to the model, all the TRF remain in the equation by the same order, and the m13GRS persisted as an independent predictor for CAD risk (OR=1.7; 95% CI: 1.4–2.0; p<0.0001).

Conclusion

TCF21 rs12190287 is a risk factor for CAD in the Portuguese population, either individually or incorporated in a m13GRS. TCF21 risk is independent from TRF. In the future, TCF21 can provide a new clues to identify patients at high cardiovascular risk and become a potential target for gene therapy.

P6200Effect of LPA gene on CAD risk among diabetic patients

Introduction

Previous research reported that LPA gene is a strong and independent predictor of CAD in non-diabetic patients but not in patients with type 2 diabetes. These results suggest that LPA gene might contribute less to CAD risk in patients with T2DM than in general population.

Objective

Investigate, in our population, the association between LPA gene CT variant and CAD risk among diabetic patients.

Methods

3050 individuals (1619 coronary patients and 1431 controls) were genotyped for LPA rs3798220 TT/CT. Pearson's chi-squared test was applied to evaluate the association between LPA variants and CAD, firstly, in the general population and, secondly, in the group of patients with T2DM (n=735). Multivariate logistic regression was performed with LPA CT variant and 6 traditional risk factors (TRF) (smoking, dyslipidemia, diabetes, hypertension, family history of CAD and physical inactivity) in both general and diabetic population.

Results

In total population, LPA CT variant was found to be strongly and significantly associated with CAD with an OR of 2.32 (95% CI: 1.56–3.45; p<0.0001). However, this association was less pronounced in the diabetic population with a CAD risk of 1.38 (95% CI: 0.56–3.43) without statistical significance (p=0.485). In the presence of 6 major TRF, multivariate analysis showed that LPA CT remained a strong and independent predictor of CAD risk (OR= 2.34; 95% CI: 1.52–3.62; p<0.0001). In diabetic population, LPA was no longer an independent predictor for CAD by multivariate analysis.

Conclusions

Our results show that the effect of LPA gene on CAD risk among diabetic patients might be different from that in the general population. Diabetes status is such a strong risk factor that may attenuate the genetic effects of LPA on CAD risk. This may indicate a complex role of Lp (a) and diabetes interaction in cardiometabolic diseases.

P6196Lipoprotein (a) and cardiovascular risk: are women at increased risk?

Introduction

Coronary artery disease (CAD) is the leading cause of death worldwide, placing a major economic and resource burden on health and public health systems, so efforts are being made to accurately predict risk for major adverse cardiac events (MACE). The field of risk prediction and CAD prevention continues to evolve with the identification of novel risk factors and biomarkers, such as lipoprotein a [Lp)a]. Almost 20% of the population has elevated circulating levels of Lp(a), which is recognized as an independent risk factor for CAD, stroke, peripheral arterial disease, and aortic stenosis. Importantly, studies showed that this was particularly true for women.

Objective

To evaluate if the elevation of Lp(a) is associated with MACE in female, male or both.

Materials and methods

Case control study of 3050 subjects from the GENEMACOR study population. In female population (n=676): cases were 341 patients with at least one >75% coronary stenosis (median age 55.7±7.2) and 335 normal controls (median age 55.8±6) adjusted by age with cases. In male population (n=2374): 1278 patients with at least one >75% coronary stenosis (median age 52.7±8) and 1096 controls (median age 51.9±8) also adjusted by age. χ2 and T student tests were used to analyze the demographic, laboratorial, angiographic and anthropometric characteristics of the population. Lipoprotein (a) was determined by immunoturbidimetry. High Lp(a) level was considered if superior to 30 mg/dl. Logistic regression was used to evaluate Lp(a) as a risk factor for CAD in total, female and male populations.

Results

In female population 44.0% patients vs 21.2% controls (p<0.000) had Lp(a)>30mg/dl. In male population 39.4% patients vs 23.8% controls (p<0.000) had Lp(a)>30mg/dl. In total population Lp(a)>30mg/dl was a predictor for CAD (OR 2.24, 95% CI: 1.91–2.62, p<0.0001). Analyzing by gender, Lp(a)>30mg/dl was also a predictor for CAD either in male (OR 2.08, 95% CI: 1.74–2.5, p<0.0001) or female population (OR 2.92, 95% CI: 2.08–4.09, p<0.0001).

Conclusions

As opposed to other studies, in our population elevated Lp(a) levels (>30mg/dl) were associated with elevated CAD risk, in both men and women. We conclude that Lp(a) can be considered an independent risk factor for CAD disease in our population, and further strategies for Lp(a) reduction may indeed translate in improved outcomes in CAD disease.

P2486The association between genetic variant ZNF259 and decreased kidney function in the diabetic patients

Aim

Investigate whether the reduction of GFR is a direct consequence of T2D or there are other genetic mechanisms involved in the pathophysiology of the evolution to chronic kidney disease.

Methods

Cross-sectional study with a total of 2579 individuals was performed, of which 735 patients had T2D. Subjects were classified as `'diabetic” if they were taking oral anti-diabetic medication or insulin or if their fasting plasma glucose was higher than 7.0 mmol/l or 126 mg/dl. Within the diabetic group, we considered those with (n=63) and without (n=627) decreased GFR. GFR was calculated through the Cockcroft and Gault formula and decreased GFR was defined as GFR<60 ml/min/1.73m2. Twenty-four genetic variants associated with T2D, metabolic syndrome, dyslipidemia and hypertension were investigated for its impact on GFR, namely: MTHFR 677 and 1298; MTHFD1L; PON 55, 192 and 108; ATIR A/C; AGT M235T; ACE I/D; TCF7L2; SLC30A8; MC4R; ADIPOQ; FTO; TAS2R50; HNF4A; IGF2BP2; PPARG; PCSK9; KIF6; ZNF259; LPA; APOE; PSRS1. Risk factors for decreased GFR were also evaluated (essential hypertension, glycaemia >120 mg/ml, dyslipidemia, alcohol consumption, CAD diagnosis). A logistic regression was performed firstly with the risk factors solely; and secondly adding the genetic variants in order to evaluate the independent predictors of progression to renal failure in T2D.

Results

After the first multivariate logistic regression with all the risk factors for decreased GFR, only CAD remained in the equation, showing to be an independent risk factor for progression to renal failure, in T2D (OR=4.17; 95% CI: 1.64–10.59; p=0.003). In the second logistic regression, including risk factors and the genetic variants, only ZNF259 rs964184 showed an independent and significant association with the risk of decreased GFR (OR=3.03; 95% CI: 1.06–8.70; p=0.039).

Conclusion

This study shows that the variant ZNF259 rs964184 is associated with decreased kidney function, independently of other risk factors. This finding needs further investigation to clarify the genetic mechanism behind the association of rs964184 with decreased GFR, in Type 2 diabetes.

P3423The contribution of genetics to premature CAD through different degrees of lifestyle factors: a matter of relative significance?

Introduction

Coronary artery disease (CAD) is a multifactorial process with substantial genetic contribution. However, genetic predisposition among patients with a different number of lifestyle factors and premature CAD, remains a complex and thoroughly unexplored topic.

Objective

To evaluate, in a young population, the importance of conventional risk factors as well as of a genetic risk score in the appearance of CAD.

Methods

A case-control study was conducted with 1075 patients from the GENEMACOR study population, under 50 years-old (555 cases, 86.8% male, mean age 44.1±4.9 years and 520 controls, 86.2% male, mean age 44.3±4.8 years). Univariate analysis addressed the association of different modifiable risk factors with premature CAD. Genetic risk score (GRS) was computed comprising 33 genetic risk variants in a multiplicative method. GRS was evaluated according to the number of traditional risk factors and risk for premature CAD was estimated and its independent predictive value estimated by logistic regression.

Results

72.6% of patients had ≥3 risk factors vs 31.2% of controls (p<0.0001). In comparison with having no risk factors (rf), patients with 1 rf had an OR of 2.79 (1.19–6.53; p=0.015), patients with 2 risk factors had a OR of 6.87 (3.03–15–57, p<0.0001) and patients with 3 modifiable risk factors had a OR of 24.17 (10.87–53.73, p<0.0001) – graph 1. In this young population, mean GRS level was consistently higher among patients with coronary artery disease comparing with a healthy population (0.6±0.6 vs 0.4±0.4, p<0.0001, respectively) – graph 2. GRS in multivariate analysis, proved to be an independent predictor for premature CAD (OR 1.71, CI95% 1.25–2.34, p=0.001).

Conclusion

In our population, GRS was an independent predictor for premature CAD. In young patients with ≥3 risk factors, genetics play a less decisive role in the development of CAD. Even in young patients, modifiable risk factors should be addressed aggressively as they may represent a higher burden than genetic predisposition itself.

P4455The controversial role of genetics behind premature CAD: a plausible excuse for the young?

Introduction

The complex interaction between genes and environmental factors contribute to individual-level risk of coronary artery disease (CAD), often resulting in premature CAD. The role for genetic risk scores in premature CAD is still controversial.

Objective

To evaluate the importance of conventional risk factors and of a genetic risk score in younger and older patients with coronary artery disease

Methods

From a group of 1619 pts with angiographic documented CAD from the GENEMACOR study, we selected 1276 pts admitted for ACS and analysed them in 2 groups (group A: ≤50 years, n=491 pts, 87.2% male, mean age 44±4.9 and group B: >50 years, n=785 pts, 75.2% male, mean age 57±4.2). Univariate analysis was used to characterize the traits of each group and we used ROC curves and respective AUCs to evaluate the power of genetics in the prediction of CAD, through a Genetic Risk Score (GRS).

Results

99.3% of the young patients had at least one modifiable risk factor, 18.4% had 2 modifiable risk factors and 75.2% had 3 or more modifiable risk factors. The pattern of risk factors contributing to CAD were different among groups: family history (A: 27.5%, B: 21.4%, p=0.015) and smoking habits (A: 64.8%, B: 42.9%, p<0.001) were more frequent among patients under 50, and traditional age-linked factors like hypertension (A: 58%, B: 75.7%, p<0.001), diabetes (A: 21.6%, B: 38.6%, p<0.001) were more common in the older group. Acute ST-elevation myocardial infarction was more frequent among the young (A: 55.4%, B: 47.4%, p=0.006), as non-ST clinical presentation was higher among elder patients. Regarding angiographic presentation, single vessel CAD was higher in group A (A: 50.3%, B: 40.9%, p<0.001), while multivessel diasease was higher in group B (A: 33.3%, B: 53.9%, p<0.001). At a mean follow-up of 5 years, older patients had a worst prognosis, registering a higher rate of cardiovascular death (A: 4.1%, B: 8.6%, p=0.002) and higher MACE (A: 26.8%, B: 31%, p=0.128),. Adding the genetic risk score (GRS), we achieved only a slight improvement in the AUC for predicting CAD (0.796->0.805, p=0.0178 and 0.748->0.761, p=0.0007 in patients under and over 50, respectively).

Conclusion

Coronary artery disease is not all the same, as premature CAD shares a unique and specific pattern of risk factors, clinical presentation, angiographic severity and prognosis. Genetics should not be used as an excuse to justify premature CAD, as there is frequently more than one potentially reversible risk factor present even in young patients and the additive predictive value of GRS is modest.

Bone remodelling of the humerus after a resurfacing and a stemless shoulder arthroplasty

BACKGROUND

New implant designs, such as resurfacing and stemless implants, have been developed to improve the long-term outcomes of the shoulder arthroplasty. However, it is not yet fully understood if their influence on the bone load distribution can compromise the long-term stability of the implant due to bone mass changes. Using three-dimensional finite element models, the aim of the present study was to analyse the bone remodelling process of the humerus after the introduction of resurfacing and stemless implants based on the Global C.A.P. and Sidus Stem-Free designs, respectively.

METHODS

The 3D geometric model of the humerus was generated from the CT data of the Visible Human Project and the resurfacing and stemless implants were modelled in Solidworks. Considering a native humerus model, a humerus model with the resurfacing implant, and a humerus model with the stemless implant, three finite element models were developed in Abaqus. Bone remodelling simulations were performed considering healthy and poor bone quality conditions. The loading condition considered comprised 6 load cases of standard shoulder movements, including muscle and joint reaction forces estimated by a multibody model of the upper limb.

FINDINGS

The results showed similar levels of bone resorption for the resurfacing and stemless implants for common humeral regions. The regions underneath the head of the resurfacing implant, unique to this design, showed the largest bone loss. For both implants, bone resorption was more pronounced for the poor bone quality condition than for the healthy bone quality condition.

INTERPRETATION

The stemless implant lost less density at the fixation site, which might suggest that these implants may be better supported in the long-term than the resurfacing implants. However, further investigation is necessary to allow definite recommendations.