No Association Between Risk of Anterior Cruciate Ligament Rupture and Selected Candidate Collagen Gene Variants in Female Elite Athletes From High-Risk Team Sports

Single Nucleotide Polymorphisms and Tendon/Ligament Injuries in Athletes: A Systematic Review and Meta-analysis

This systematic review and meta-analysis aimed to identify the association between genetic polymorphisms and tendon and ligament injuries in adolescent and adult athletes of multiple competition sports. The PubMed, Web of Science, EBSCO, Cochrane Library, and MEDLINE databases were searched until July 7, 2023. Eligible articles included genetic studies on tendon and ligament injuries and comparisons between injured and non-injured athletes. This review included 31 articles, comprising 1,687 injury cases and 2,227 controls, from a meta-analysis of 12 articles. We identified 144 candidate gene polymorphisms (only single nucleotide polymorphisms were identified). The meta-analyses included vascular endothelial growth factor A (VEGFA) rs699947, collagen type I alpha 1 rs1800012, collagen type V alpha 1 rs12722, and matrix metalloproteinase 3 rs679620. The VEGFA rs699947 polymorphism showed a lower risk of injuries in athletes with the C allele ([C vs. A]: OR=0.80, 95% CI: 0.65-0.98, I 2 =3.82%, p=0.03). The risk of these injuries were not affected by other polymorphisms. In conclusion, the VEGFA rs699947 polymorphism is associated with the risk of tendon and ligament injuries in athletes. This study provides insights into genetic variations that contribute to our understanding of the risk factors for such injuries in athletes.

Associations of collagen type 1 α1 gene polymorphisms and musculoskeletal soft tissue injuries: a meta-analysis with trial sequential analysis

Numerous studies have investigated the role of collagen type 1 α1 (COL1A1) polymorphisms in musculoskeletal soft tissue injuries (MSTIs), yielding conflicting results. This study was designed to synthesize existing evidence and clarify the relationship between COL1A1 polymorphisms and MSTI susceptibility. We conducted a comprehensive literature search using PubMed, Cochrane Library, Web of Science, EMBASE, and Wanfang databases. Associations were assessed using odds ratios (ORs) with 95% confidence intervals (95% CIs) across five genetic models. Subgroup analyses were performed based on ethnicity and injury type. Additionally, trial sequential analysis (TSA) was utilized to assess information size and statistical power. We analyzed a total of 16 articles from 358 retrieved studies, encompassing 2094 MSTI cases and 4105 controls. Our pooled data revealed that individuals with the TT genotype of the rs1800012 polymorphism had a significantly reduced risk of MSTIs (TT vs. GG, OR = 0.53, 95% CI 0.35-0.82, P = 0.004; TT vs. TG + GG, OR = 0.54, 95% CI 0.36-0.80, P = 0.002). Ethnicity-based stratification showed a significant association in Caucasians but not Asians. However, no significant association was observed between the rs1107946 polymorphism and MSTIs, regardless of ethnicity or injury type. TSA indicated that the sample sizes may have been insufficient to yield conclusive results. In conclusion, our study supports the protective effect of the TT genotype of the rs1800012 polymorphism against MSTIs, particularly among Caucasians. However, the rs1107946 polymorphism does not appear to influence MSTI susceptibility.

The Impact of Genetic Polymorphisms on Anterior Cruciate Ligament Injuries in Athletes: A Meta-Analytical Approach

This meta-analysis aimed to investigate the association between genetic polymorphisms in Collagen type 1 alpha-1 (COL1A1), Collagen type 3 alpha-1 (COL3A1), Collagen type 5 alpha-1 (COL5A1), and Collagen type 12 alpha-1 (COL12A1) genes and anterior cruciate ligament (ACL) injuries in athletes. A systematic search was diligently conducted on the PubMed and Web of Science databases to identify relevant studies on 5-9 September 2023. Only case-control studies were included in the meta-analysis. A total of 19 studies were reviewed, involving the analysis of 3522 cases and 6399 control subjects. Data relevant to the study objectives were extracted from these chosen studies and subsequently analyzed using either a random-effects or fixed-effects model. It indicates that individuals carrying the G allele in the COL1A1 (rs1107946) gene have a decreased risk of anterior cruciate ligament injuries (OR: -0.27, 95% CI: -0.42 to -0.12, p < 0.001). A similar relationship was observed in the dominant model, but this relationship was reversed in the recessive model (OR: 0.69, 95% CI: 0.33 to 1.05, p < 0.001). However, no significant associations were found in the COL3A1 (rs1800255) and COL5A1 (rs12722) genes. In the COL12A1 (rs970547) gene, the A allele was associated with an increased risk of anterior cruciate ligament injuries (OR: 0.18, 95% CI: 0.01 to 0.36, p = 0.041). This meta-analysis suggests that genetic variants in COL1A1 (rs1107946) and COL12A1 (rs970547) may be associated with ACL injuries in athletes. However, COL3A1 rs1800255 and COL5A1 rs12722 gene variants do not appear to have a significant association with these injuries.

Genome-wide association study identifying variants related to performance and injury in high-performance athletes

A growing body of evidence exists supporting the role that genetic variation plays in athletic performance and injury. This study sought to identify genetic variants associated with performance and lower limb musculoskeletal injury in a high-level athletic cohort. A total of 126 Estonian National Team members (Olympic athletes and participants of International Championships) (104 males, 82.5%) underwent a genome-wide association analysis between 2017 and 2018, to identify single-nucleotide polymorphisms (SNPs) associated with performance and/or injury. The athletic cohort was stratified within each sport based on performance and whether they were a medalist (n = 29) or not (n = 97), whether they sustained an injury (n = 47) or not (n = 79), and the type of injury (patella tendinopathy n = 22, Achilles tendinopathy n = 17, hamstring injury n = 3, anterior cruciate ligament rupture n = 6). Three SNPs demonstrated strong genome-wide association with athletic performance (podium/medalist versus not), including DSG1 (rs10502567, OR 14.3) and DSG4 (rs73410248, OR 17.4), while 76 SNPs demonstrated suggestive significance. Overall, 37 SNPs gave genome-wide suggestive association with any type of injury, including PAPPA2 (rs11580456, OR 13.8) and MAS1 (rs220735, rs170219, OR 3.1) which demonstrated positive signal with multiple SNPs. Several genes demonstrated positive association for the specific injury types, including COL22A1 (rs3924862) and PLXNA2 (rs11799530), as well as PAPPA2 (rs11580456), DOK5 (rs73142922), GNG12 (rs28435277), and DAP (rs267959, rs2930047, rs1080440, rs267939). The current study identified genetic variants associated with high-level athletic performance and musculoskeletal injury. Further work is required to permit integration of this and future knowledge into individualized training practices, as well as injury mitigation and rehabilitation programs.

Are commercial genetic injury tests premature?

INTRODUCTION

Several direct-to-consumer (DTC) genetic testing companies have emerged that claim to be able to test for susceptibility for musculoskeletal injuries. Although there are several publications on the emergence of this industry, none have critically evaluated the evidence for the use of genetic polymorphisms in commercial tests. The aim of this review was to identify, where possible, the polymorphisms and to evaluate the current scientific evidence for their inclusion.

RESULTS

The most common polymorphisms included COL1A1 rs1800012, COL5A1 rs12722, and GDF5 rs143383. The current evidence suggests that it is premature or even not viable to include these three polymorphisms as markers of injury risk. A unique set of injury-specific polymorphisms, which do not include COL1A1, COL5A1, or GDF5, identified from genome-wide association studies (GWAS) is used by one company in their tests for 13 sports injuries. However, of the 39 reviewed polymorphisms, 22 effective alleles are rare and absent in African, American, and/or Asian populations. Even when informative in all populations, the sensitivity of many of the genetic markers was low and/or has not been independently validated in follow-up studies.

CONCLUSIONS

The current evidence suggests it is premature to include any of the reviewed polymorphisms identified by GWAS or candidate gene approaches in commercial genetic tests. The association of MMP7 rs1937810 with Achilles tendon injuries, and SAP30BP rs820218 and GLCCI1 rs4725069 with rotator cuff injuries does warrant further investigation. Based on current evidence, it remains premature to market any commercial genetic test to determine susceptibility to musculoskeletal injuries.

Risk Factors for Revision or Rerupture After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

The rerupture or need for revision after anterior cruciate ligament reconstruction (ACLR) is a serious complication. Preventive strategies that target the early identification of risk factors are important to reduce the incidence of additional surgery.

PURPOSE

To perform a systematic review and meta-analysis to investigate risk factors for revision or rerupture after ACLR.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

Literature searches were performed in PubMed, Embase, and Web of Science from database inception to November 2021 and updated in January 2022. Quantitative, original studies reporting potential adjusted risk factors were included. Odds ratios (ORs) were calculated for potential risk factors.

RESULTS

A total of 71 studies across 13 countries with a total sample size of 629,120 met the inclusion criteria. Fifteen factors were associated with an increase in the risk of revision or rerupture after ACLR: male sex (OR, 1.27; 95% CI, 1.14-1.41), younger age (OR, 1.07; 95% CI, 1.05-1.08), lower body mass index (BMI) (OR, 1.03; 95% CI, 1.00-1.06), family history (OR, 2.47; 95% CI, 1.50-4.08), White race (OR, 1.32; 95% CI, 1.08-1.60), higher posterolateral tibial slope (OR, 1.15; 95% CI, 1.05-1.26), preoperative high-grade anterior knee laxity (OR, 2.30; 95% CI, 1.46-3.64), higher baseline Marx activity level (OR, 1.07; 95% CI, 1.02-1.13), return to a high activity level/sport (OR, 2.03; 95% CI, 1.15-3.57), an ACLR within less than a year after injury (OR, 2.05; 95% CI, 1.81-2.32), a concomitant medial collateral ligament (MCL) injury (OR, 1.62; 95% CI, 1.31-2.00), an anteromedial portal or transportal technique (OR, 1.36; 95% CI, 1.22-1.51), hamstring tendon (HT) autografts (vs bone-patellar tendon-bone [BPTB] autografts) (OR, 1.60; 95% CI, 1.40-1.82), allografts (OR, 2.63; 95% CI, 1.65-4.19), and smaller graft diameter (OR, 1.21; 95% CI, 1.05-1.38). The other factors failed to show an association with an increased risk of revision or rerupture after ACLR.

CONCLUSION

Male sex, younger age, lower BMI, family history, White race, higher posterolateral tibial slope, preoperative high-grade anterior knee laxity, higher baseline Marx activity level, return to a high activity level/sport, an ACLR within less than a year from injury, a concomitant MCL injury, an anteromedial portal or transportal technique, HT autografts (vs BPTB autografts), allografts, and smaller graft diameter may increase the risk of revision or rerupture after ACLR. Raising awareness and implementing effective preventions/interventions for risk factors are priorities for clinical practitioners to reduce the incidence of revision or rerupture after ACLR.

Genetic Determinants of the Anterior Cruciate Ligament Rupture in Sport: An Up-to-Date Systematic Review

Anterior cruciate ligament injuries (ACLIs) are one of the most common knee injuries in sports. Although numerous factors have been related to the risk of ACLIs, it is still unclear why some individuals are more susceptible than others due to the intricate etiology of ACLIs. Several genetic factors have been identified as contributing to ACLIs. This systematic review summarizes the current evidence regarding the genetic causes of ACLIs based on the available literature. Five electronic databases were searched from 2017 to 2022. All titles, abstracts, and full texts were reviewed in detail to determine the inclusions and exclusions. The Newcastle-Ottawa Scale was used to evaluate the risk of bias. The studies' characteristics and results are presented in both narrative and tabular formats. A total of 24 studies examined 31 genes and 62 variants associated with ACLIs in the global population. Ten studies investigated seven collagens and ten SNPs for the ACL injury. The majority of studies found no significant difference in the association of the COL1A1 rs1800012, COL5A1 rs12722, VEGFA rs1570360, IL6R rs2228145, IL6 rs1800795, IL1B rs16944 and rs1143627, however, contrary results were found when nationality and gender were considered together. Conflicting evidence was found for polymorphisms rs2010963, rs699947 of the VEGFA gene in different studies. Due to a lack of data, it was impossible to determine the relationship between the anterior cruciate ligament rupture (ACLR) and the other polymorphisms. More research is required to establish a clear relationship between the ACLR and genetic variants, particularly when gender and nationality are taken into account separately.

Genetic variants within the COL5A1 gene are associated with ligament injuries in physically active populations from Australia, South Africa, and Japan

Previous small-scale studies have shown an association between the COL5A1 gene and anterior cruciate ligament (ACL) injury risk. In this larger study, the genotype and allele frequency distributions of the COL5A1 rs12722 C/T and rs10628678 AGGG/deletion (AGGG/-) indel variants were compared between participants: (i) with ACL injury in independent and combined cohorts from South-Africa (SA) and Australia (AUS) vs controls (CON), and (ii) with any ligament (ALL) or only ACL injury in a Japanese (JPN) cohort vs CON. Samples were collected from SA (235 cases; 232 controls), AUS (362 cases; 80 controls) and JPN (500 cases; 1,403 controls). Genomic DNA was extracted and genotyped. Distributions were compared, and inferred haplotype analyses performed. No independent associations were noted for rs12722 or rs10628678 when the combined SA + AUS cohort was analysed. However, the C-deletion (rs12722-rs10628678) inferred haplotype was under-represented (p = 0.040, OR = 0.15, CI = 0.04-0.56), while the T-deletion inferred haplotype was over-represented in the female SA + AUS ACL participants versus controls (p < 0.001, OR = 4.74, CI = 1.66-13.55). Additionally, the rs12722 C/C genotype was under-represented in JPN CON vs ACL (p = 0.039, OR = 0.52, 0.27-1.00), while the rs10628678 -/- genotype was associated with increased risk of any ligament injuries (p = 0.035, OR = 1.31, CI = 1.02-1.68) in the JPN cohort. Collectively, these results highlight that a region within the COL5A1 3'-UTR is associated with ligament injury risk. This must be evaluated in larger cohorts and its functional relevance to the structure and capacity of ligaments and joint biomechanics be explored.Highlights The COL5A1 T-deletion inferred haplotype (rs12722-rs10628678) was associated with an increased risk of ACL rupture in the combined SA and AUS female participants.The COL5A1 C-deletion inferred haplotype (rs12722-rs10628678) was associated with a decreased risk of ACL rupture in the combined SA and AUS female participants.The COL5A1 rs12722 C/C and rs10628678 -/- genotypes were associated with increased risk of ACL rupture and of ligament injuries in JPN, respectively.A region within the COL5A1 3'-UTR is associated with risk of ligament injury, including ACL rupture, and therefore the functional significance of this region on ligament capacity and joint biomechanics requires further exploration.

Sex Differences in the Association between Risk of Anterior Cruciate Ligament Rupture and COL5A1 Polymorphisms in Elite Footballers

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in collagen genes are predisposing factors for anterior cruciate ligament (ACL) rupture. Although these events are more frequent in females, the sex-specific risk of reported SNPs has not been evaluated.

PURPOSE

We aimed to assess the sex-specific risk of historic non-contact ACL rupture considering candidate SNPs in genes previously associated with muscle, tendon, ligament and ACL injury in elite footballers.

STUDY DESIGN

This was a cohort genetic association study.

METHODS

Forty-six (twenty-four females) footballers playing for the first team of FC Barcelona (Spain) during the 2020-21 season were included in the study. We evaluated the association between a history of non-contact ACL rupture before July 2022 and 108 selected SNPs, stratified by sex. SNPs with nominally significant associations in one sex were then tested for their interactions with sex on ACL.

RESULTS

Seven female (29%) and one male (4%) participants had experienced non-contact ACL rupture during their professional football career before the last date of observation. We found a significant association between the rs13946 C/C genotype and ACL injury in women footballers (p = 0.017). No significant associations were found in male footballers. The interaction between rs13946 and sex was significant (p = 0.027). We found that the C-allele of rs13946 was exclusive to one haplotype of five SNPs spanning COL5A1.

CONCLUSIONS

The present study suggests the role of SNPs in genes encoding for collagens as female risk factors for ACL injury in football players.

CLINICAL RELEVANCE

The genetic profiling of athletes at high risk of ACL rupture can contribute to sex-specific strategies for injury prevention in footballers.

Anterior cruciate ligament injury and its postoperative outcomes are not associated with polymorphism in COL1A1 rs1107946 (G/T): a case-control study in the Middle East elite athletes

BACKGROUND

It is unclear what role COL1A1 polymorphisms play in anterior cruciate ligament (ACL) injury pathophysiology. The present study investigated the relationship between COL1A1-1997 guanine (G)/thymine (T) (rs1107946) polymorphism and ACL injury. Moreover, the possible effect of this polymorphism on the postoperative outcomes of ACL reconstruction surgery was evaluated.

METHODS

This prospective case-control study was performed on 200 young professional men with an ACL tear who underwent arthroscopic ACL reconstruction surgery. Moreover, 200 healthy athletes without a history of tendon or ligament injury who were matched with the case group were selected as the control group. DNA was extracted from the leukocytes of participants, and the desired allele was genotyped. Clinical outcomes were collected for the case group before and one year after surgery.

RESULTS

The genotype distribution was in accordance with the Hardy-Weinberg principle. In the ACL injury group, the G allele frequency was non-significantly higher than the healthy controls, with an odds ratio [95% CI] of 1.08 [0.79-1.47] (P = 64). We did not find a significant difference between the genotype of individuals-GG, GT, and TT-in the case and control groups (P > 0.05). Clinical outcomes of the ACL tear group were significantly improved in terms of preoperative values. However, none of them were significantly different between the three genotypes (GG, GT, and TT).

CONCLUSION

According to the findings of the present investigation, single-nucleotide polymorphism (SNP) at COL1A1 rs1107946 (G/T) was not a predisposing genetic factor for ACL injury in a young professional male athlete population in the Middle East. Furthermore, patients' responses to treatment were not different between distinct genotypes.

LEVEL OF EVIDENCE III

A whole genome sequencing approach to anterior cruciate ligament rupture-a twin study in two unrelated families

Predisposition to anterior cruciate ligament (ACL) rupture is multi-factorial, with variation in the genome considered a key intrinsic risk factor. Most implicated loci have been identified from candidate gene-based approach using case-control association settings. Here, we leverage a hypothesis-free whole genome sequencing in two two unrelated families (Family A and B) each with twins with a history of recurrent ACL ruptures acquired playing rugby as their primary sport, aimed to elucidate biologically relevant function-altering variants and genetic modifiers in ACL rupture. Family A monozygotic twin males (Twin 1 and Twin 2) both sustained two unilateral non-contact ACL ruptures of the right limb while playing club level touch rugby. Their male sibling sustained a bilateral non-contact ACL rupture while playing rugby union was also recruited. The father had sustained a unilateral non-contact ACL rupture on the right limb while playing professional amateur level football and mother who had participated in dancing for over 10 years at a social level, with no previous ligament or tendon injuries were both recruited. Family B monozygotic twin males (Twin 3 and Twin 4) were recruited with Twin 3 who had sustained a unilateral non-contact ACL rupture of the right limb and Twin 4 sustained three non-contact ACL ruptures (two in right limb and one in left limb), both while playing provincial level rugby union. Their female sibling participated in karate and swimming activities; and mother in hockey (4 years) horse riding (15 years) and swimming, had both reported no previous history of ligament or tendon injury. Variants with potential deleterious, loss-of-function and pathogenic effects were prioritised. Identity by descent, molecular dynamic simulation and functional partner analyses were conducted. We identified, in all nine affected individuals, including twin sets, non-synonymous SNPs in three genes: COL12A1 and CATSPER2, and KCNJ12 that are commonly enriched for deleterious, loss-of-function mutations, and their dysfunctions are known to be involved in the development of chronic pain, and represent key therapeutic targets. Notably, using Identity By Decent (IBD) analyses a long shared identical sequence interval which included the LINC01250 gene, around the telomeric region of chromosome 2p25.3, was common between affected twins in both families, and an affected brother'. Overall gene sets were enriched in pathways relevant to ACL pathophysiology, including complement/coagulation cascades (p = 3.0e-7), purine metabolism (p = 6.0e-7) and mismatch repair (p = 6.9e-5) pathways. Highlighted, is that this study fills an important gap in knowledge by using a WGS approach, focusing on potential deleterious variants in two unrelated families with a historical record of ACL rupture; and providing new insights into the pathophysiology of ACL, by identifying gene sets that contribute to variability in ACL risk.

Predicting ACL Injury Using Machine Learning on Data From an Extensive Screening Test Battery of 880 Female Elite Athletes

BACKGROUND

Injury risk prediction is an emerging field in which more research is needed to recognize the best practices for accurate injury risk assessment. Important issues related to predictive machine learning need to be considered, for example, to avoid overinterpreting the observed prediction performance.

PURPOSE

To carefully investigate the predictive potential of multiple predictive machine learning methods on a large set of risk factor data for anterior cruciate ligament (ACL) injury; the proposed approach takes into account the effect of chance and random variations in prediction performance.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The authors used 3-dimensional motion analysis and physical data collected from 791 female elite handball and soccer players. Four common classifiers were used to predict ACL injuries (n = 60). Area under the receiver operating characteristic curve (AUC-ROC) averaged across 100 cross-validation runs (mean AUC-ROC) was used as a performance metric. Results were confirmed with repeated permutation tests (paired Wilcoxon signed-rank-test; P < .05). Additionally, the effect of the most common class imbalance handling techniques was evaluated.

RESULTS

For the best classifier (linear support vector machine), the mean AUC-ROC was 0.63. Regardless of the classifier, the results were significantly better than chance, confirming the predictive ability of the data and methods used. AUC-ROC values varied substantially across repetitions and methods (0.51-0.69). Class imbalance handling did not improve the results.

CONCLUSION

The authors' approach and data showed statistically significant predictive ability, indicating that there exists information in this prospective data set that may be valuable for understanding injury causation. However, the predictive ability remained low from the perspective of clinical assessment, suggesting that included variables cannot be used for ACL prediction in practice.

Gene Variants Previously Associated with Reduced Soft Tissue Injury Risk: Part 1 - Independent Associations with Elite Status in Rugby

AbstractThere is growing evidence of genetic contributions to tendon and ligament pathologies. Given the high incidence and severity of tendon and ligament injuries in elite rugby, we studied whether 13 gene polymorphisms previously associated with tendon/ligament injury were associated with elite athlete status. Participants from the RugbyGene project were 663 elite Caucasian male rugby athletes (RA) (mean (standard deviation) height 1.85 (0.07) m, mass 101 (12) kg, age 29 (7) yr), including 558 rugby union athletes (RU) and 105 rugby league athletes. Non-athletes (NA) were 909 Caucasian men and women (56% female; height 1.70 (0.10) m, mass 72 (13) kg, age 41 (23) yr). Genotypes were determined using TaqMan probes and groups compared using Χ² and odds ratio (OR). COLGALT1 rs8090 AA genotype was more frequent in RA (27%) than NA (23%; P = 0.006). COL3A1 rs1800255 A allele was more frequent in RA (26%) than NA (23%) due to a greater frequency of GA genotype (39% vs 33%). For MIR608 rs4919510, RA had 1.7 times the odds of carrying the CC genotype compared to NA. MMP3 rs591058 TT genotype was less common in RA (25.1%) than NA (31.2%; P < 0.04). For NID1 rs4660148, RA had 1.6 times the odds of carrying the TT genotype compared to NA. It appears that elite rugby athletes have an inherited advantage that contributes to their elite status, possibly via resistance to soft tissue injury. These data may, in future, assist personalized management of injury risk amongst athletes.

Association of COL5A1 gene polymorphisms and musculoskeletal soft tissue injuries: a meta-analysis based on 21 observational studies

Objective

Inconsistent findings existed on the correlation of collagen type V α1 (COL5A1) gene polymorphisms and musculoskeletal soft tissue injuries (MSTIs). The purpose of this study was to collect and combine the current evidences by a meta-analysis approach.

Methods

Six online databases were searched up to August, 2021. The methodological quality of each individual study was evaluated based upon Newcastle–Ottawa Scale (NOS). The strength of the effect size was presented by odds ratio (OR) with 95% confidence interval (95%CI) in five genetic models. The data were analyzed using Review Manager 5.3.

Results

Twenty-one studies were eligible to this meta-analysis. The study quality was deemed fair to excellent according to NOS. In the overall analyses, the merged data suggested that rs12722, rs71746744, and rs3196378 polymorphisms were correlated to an increased susceptibility to MSTIs. But the association was not established in rs13946 or rs11103544 polymorphism. For rs12722 polymorphism, stratified analyses by injury type and ethnicity identified the association mainly existed in ligament injury and among Caucasian population. For rs13946 polymorphism, subgroup analysis suggested the association existed in tendon and ligament injuries.

Conclusion

This study supports that rs12722 is associated with an elevated susceptibility to ligament injury, especially in the Caucasian population. Rs13946 polymorphism appears to increase the risk to tendon and ligament injuries. Rs71746744 and rs3196378 polymorphisms have a tendency to confer an elevated risk to MSTIs. However, no relevance is found between rs11103544 polymorphism and MSTIs.

EFFECTS OF GENETIC VARIATIONS OF MLCK2, AMPD1, AND COL5A1 ON MUSCLE ENDURANCE

ABSTRACT Introduction: Although potential relationships with genetic variants of MLCK2, AMPD1 and COL5A1 have been detected in molecular studies evaluating sports performance from the genetic perspective, there are limited data in terms of muscle endurance and physical fitness. Materials and Methods: This study aimed to evaluate these variants in terms of lower limb muscle endurance and physical fitness in thirty-three soccer players. Genotypes were determined by High Resolution Melting (HRM) analysis in qPCR after genomic DNA was isolated from buccal swab samples from the participants. Measurements of lower limb muscle endurance, the dynamic leap and balance test (DLBT), and the standing broad jump test (SBJ) were taken for all the participants. Results: Greater height (p = 0.006), higher DLBT (p = 0.016) and SBJ (p = 0.033) scores, as well as greater left hip adduction (p <0.001), were detected in those with the CT genotype for AMPD1 as compared to those with CC. For MLCK rs28497577, it was found that the players carrying the AA genotype were taller (p = 0.046), heavier (p = 0.049), and had greater left knee extension (p=0.014) and left foot plantar flexion (p =0.040) than those carrying the C allele. Those with the CT genotype for COL5A1 rs12722 had greater right hip extension (p = 0.040) and right knee extension (p = 0.048) than those with the CC genotype. Conclusions: Our results showed that MLCK2 and COL5A1 gene variants are associated with body composition and lower limb muscle endurance, and the presence of the AMPD1 CT genotype may contribute positively to balance, correct positioning, controlled strength, and hip mobility. Evidence level II; Comparative prospective study .

Influence of type I collagen polymorphisms and risk of anterior cruciate ligament rupture in athletes: a case-control study

Background

Anterior cruciate ligament (ACL) rupture is a common and severe knee injury in sports and occurs mostly due to noncontact injuries. There is an increasing amount of evidence associating ACL rupture to single nucleotide polymorphisms (SNPs), and SNPs in the collagen type I genes can change its expression and tissue mechanical features. This study aimed to investigate the association between SNPs in COL1A1 and COL1A2 with sports-related ACL tears.

Methods

A total of 338 athletes from multiple sports modalities were analyzed: 146 were diagnosed with ACL rupture or underwent an ACL reconstruction surgery and 192 have no musculoskeletal injuries. SNPs were genotyped using validated TaqMan assays. The association of the polymorphisms with ACL rupture was evaluated by a multivariable logistic regression model, using odds ratios (OR) and 95% confidence intervals (CI).

Results

The age, sport modality, and training location were associated with an increased risk of a non-contact ACL tear. COL1A2 SNPs (rs42524 CC and rs2621215 GG) were associated with an increased risk of non-contact ACL injury (6 and 4-fold, respectively). However, no significant differences were detected in the distribution of COL1A1 rs1107946 and COL1A2 rs412777 SNPs between cases and controls. There was a protective association with ACL rupture (OR = 0.25; 95% CI = 0.07–0.96) between COL1A1 rs1107946 (GT or TT) and the wildtype genotypes of the three COL1A2 (rs412777, rs42524, rs2621215). COL1A2 rs42524 and rs2621215 SNPs were associated with non-contact ACL risk.

Conclusion

The combined analysis of COL1A1-COL1A2 genotypes suggests a gene-gene interaction in ACL rupture susceptibility.

COL12A1 rs970547 Polymorphism Does Not Alter Susceptibility to Anterior Cruciate Ligament Rupture: A Meta-Analysis

Objective: Currently available evidence regarding the association between collagen type XII α1 (COL12A1) polymorphism and risk of anterior cruciate ligament rupture (ACLR) remains elusive. The aim of our present study was to assess the association between COL12A1 rs970547 polymorphism and ACLR risk.

Methods: Five online databases, namely, PubMed, EMBASE, ISI Web of Science, CENTRAL, and CNKI, were searched from their inception data up to December 2020 to identify relative observational studies. The methodological quality of each individual study was evaluated using the Newcastle-Ottawa Scale (NOS). The “model-free approach” was employed to estimate the magnitude of effect of COL12A1 rs970547 polymorphism on ACLR, and the association was expressed using odds ratio (OR) and its associated 95% confidence interval (95% CI). Subgroup analysis was performed by ethnicity and sex of included subjects.

Results: Eight studies involving 1,477 subjects with ACLR and 100,439 healthy controls were finally included in our study. The methodological quality of included studies was deemed moderate to high based on NOS scores. The “model-free” approach suggested no genotype differences between ACLR and healthy control for the rs970547 polymorphism, but we still used the allele model to present the combined data. Under the random-effect model, there was no significant difference in the frequency of effecting allele between ACLR and control (OR: 0.91, 95% CI 0.77, 1.08; p = 0.28). Stratified analysis by sex and ethnicity also showed no difference in allele frequency.

Conclusion: The findings of this current meta-analysis suggested that rs970547 was not associated with ACLR risk in male, female, and the overall population among Asians or Caucasians.

Drop Jump? Single-Leg Squat? Not if You Aim to Predict Anterior Cruciate Ligament Injury From Real-Time Clinical Assessment: A Prospective Cohort Study Involving 880 Elite Female Athletes

OBJECTIVE

To determine whether visually assessed performances of the single-leg squat (SLS) and vertical drop jump (VDJ) were associated with future noncontact anterior cruciate ligament (ACL) injury.

DESIGN

Prognostic accuracy cohort study.

METHODS

Elite female handball and football (soccer) athletes (n = 880) were tested from 2007 to 2014 and tracked through 2015. Trained physical therapists visually rated each leg during a SLS and overall control during a VDJ. Receiver operating characteristic curve, Pearson chi-square, and logistic regression analyses were used to determine the prognostic accuracy of the 2 screening tests.

RESULTS

Sixty-five noncontact ACL injuries occurred during the follow-up period. Fourteen percent of athletes who sustained an ACL injury had poor SLS performance, compared to 17% of the noninjured athletes (P = .52 and .67 for hip and knee ratings, respectively). Side-to-side asymmetry in the SLS was not different between injured and noninjured athletes (P = .10 and .99 for hip and knee asymmetry, respectively). Twenty-one percent of athletes who sustained an ACL injury had a poor VDJ rating, compared to 27% of the noninjured athletes (P = .09). Furthermore, area under the curve values ranged from 0.43 to 0.54 for the SLS and VDJ, demonstrating no to poor prognostic accuracy.

CONCLUSION

Neither SLS nor VDJ test performance distinguished between athletes who sustained a subsequent noncontact ACL injury and those who did not. J Orthop Sports Phys Ther 2021;51(7):372-378. doi:10.2519/jospt.2021.10170.

Kiss goodbye to the 'kissing knees': no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes

The aim of this study was to investigate if frontal plane knee and hip control in single-leg squats or vertical drop jumps with an overhead target were associated with future non-contact anterior cruciate ligament (ACL) injury in elite female athletes. Of the 429 handball and 451 football athletes (age 21.5 ± 4.0 years, height 169.6 ± 6.4 cm, body weight 67.1 ± 8.0 kg), 722 non-injured and 56 non-contact ACL injured participants were eligible for analysis. We calculated lateral pelvic tilt, frontal plane knee projection angle, medial knee position, and side-to-side asymmetry in these from 2D videos recorded at baseline, and recorded any new ACL injuries prospectively. None of the aforementioned variables in either screening task were different or could discriminate between injured and non-injured athletes (all p values >.05 and Cohen's d values < .27). Two-dimensional video assessment of frontal plane knee and hip control during both a single-leg squat and vertical drop jump was unable to identify individuals at increased risk of non-contact ACL injury, thus should not be used for screening.

Risk Factors for Contra-Lateral Secondary Anterior Cruciate Ligament Injury: A Systematic Review with Meta-Analysis

Background

The risk of sustaining a contra-lateral anterior cruciate ligament (C-ACL) injury after primary unilateral ACL injury is high. C-ACL injury often contributes to a further decline in function and quality of life, including failure to return to sport. There is, however, very limited knowledge about which risk factors that contribute to C-ACL injury.

Objective

To systematically review instrinsic risk factors for sustaining a C-ACL injury.

Methods

A systematic review with meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Four databases (MEDLINE, CINAHL, EMBASE, Sport Discus) were searched from inception to January 2020. Inclusion criteria were prospective or retrospective studies investigating any intrinsic risk factor for future C-ACL injury. Meta-analysis was performed and expressed as odds ratios (OR) if two or more articles assessed the same risk factor.

Results

44 moderate-to-high quality studies were eventually included in this review, whereof 35 studies were eligible for meta-analysis, including up to 59 000 individuals. We identified seven factors independently increasing the odds of sustaining a C-ACL injury (in order of highest to lowest OR): (1) returning to a high activity level (OR 3.26, 95% CI 2.10–5.06); (2) Body Mass Index < 25 (OR 2.73, 95% CI 1.73–4.36); (3) age ≤ 18 years (OR 2.42, 95% CI 1.51–3.88); (4) family history of ACL injury (OR 2.07, 95% CI 1.54–2.80); (5) primary ACL reconstruction performed ≤ 3 months post injury (OR 1.65, 95% CI: 1.32–2.06); (6) female sex (OR 1.35, 95% CI 1.14–1.61); and (7) concomitant meniscal injury (OR 1.21, 95% CI 1.03–1.42). The following two factors were associated with decreased odds of a subsequent C-ACL injury: 1) decreased intercondylar notch width/width of the distal femur ratio (OR 0.43, 95% CI 0.25–0.69) and 2) concomitant cartilage injury (OR 0.83, 95% CI 0.69–1.00). There were no associations between the odds of sustaining a C-ACL injury and smoking status, pre-injury activity level, playing soccer compared to other sports or timing of return to sport. No studies of neuromuscular function in relation to risk of C-ACL injury were eligible for meta-analysis according to our criteria.

Conclusion

This review provides evidence that demographic factors such as female sex, young age (≤ 18 years) and family history of ACL injury, as well as early reconstruction and returning to a high activity level increase the risk of C-ACL injury. Given the lack of studies related to neuromuscular factors that may be modifiable by training, future studies are warranted that investigate the possible role of factors such as dynamic knee stability and alignment, muscle activation and/or strength and proprioception as well as sport-specific training prior to return-to-sport for C-ACL injuries.

PROSPERO: CRD42020140129.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-020-01424-3.

VEGFA Promoter Polymorphisms rs699947 and rs35569394 Are Associated With the Risk of Anterior Cruciate Ligament Ruptures Among Indian Athletes: A Cross-sectional Study

Background:

Associations of genetic variants within certain fibril-forming genes have previously been observed with anterior cruciate ligament (ACL) injuries. Evidence suggests a significant role of angiogenesis-associated cytokines in remodeling the ligament fibril matrix after mechanical loading and maintaining structural and functional integrity of the ligament. Functional polymorphisms within the vascular endothelial growth factor A (VEGFA) gene have emerged as plausible candidates owing to their role in the regulation of angiogenic responses.

Hypothesis:

VEGFA promoter polymorphisms rs699947 and rs35569394 are associated with ACL injury risk among athletes.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 90 Indian athletes with radiologically confirmed or surgically proven isolated ACL tears and 76 matched-control athletes were selected for the present cross-sectional genetic association study. Oral mouthwash samples were collected from all the case and control athletes and genotyped for VEGFA rs699947 and rs35569394 using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) method.

Results:

The A allele (rs699947) was significantly overrepresented in the ACL group (C vs A allele: odds ratio [OR], 1.68 [95% CI, 1.08-2.60]; P = .021) (CC vs CA + AA: OR, 2.69 [95% CI, 1.37-5.26]; P = .004). There was a greater frequency of the AA genotype in the ACL group in comparison with the control group (OR, 3.38 [95% CI, 1.23-9.28]; P = .016) when only male athletes were compared. Likewise, there was a greater frequency of the I allele (rs35569394) in the ACL group (D vs I allele: OR, 1.64 [95% CI, 1.06-2.55]; P = .025) (DD vs ID + II: OR, 2.61 [95% CI, 1.31-5.21]; P = .006). The A-I haplotype was overrepresented in the ACL group compared with the control group (OR, 1.68 [95% CI, 1.08-2.60]; χ² = 5.320; P = .021), and both the polymorphisms were found to be in complete linkage disequilibrium (r² = 0.929; logarithm of the odds score = 63.74; D′ = 1.0). Female athletes did not show any difference in genotype or allele frequency.

Conclusion:

This is the first study to investigate the association of VEGFA promoter polymorphisms in ACL tears among Indian athletes. Increased frequencies of the A allele (rs699947) and I allele (rs35569394) were observed in the ACL group. These results suggest that sequence variants in the VEGF gene are associated with ACL injury risk among athletes. Further research with long-term follow-ups measuring VEGF expression levels during recovery is warranted to establish its role in ACL injuries and healing.

Functional COL1A1 variants are associated with the risk of acute musculoskeletal soft tissue injuries

Studies have reported the association of the COL1A1 Sp1 binding site variant (rs1800012) with the risk of acute musculoskeletal soft tissue injuries. Interaction with the COL1A1 promoter variant (rs1107946) has also been proposed to modulate acute injury risk. Conversely, neither of these loci have been associated with chronic musculoskeletal soft tissue phenotypes. Therefore, the primary aim of this study involved characterizing these variants in a cohort of participants with chronic Achilles tendinopathy. Second, this study aimed to support the contribution of the rs1107946 and rs1800012 variants to the profile predisposing for acute musculoskeletal soft tissue injuries including Achilles tendon and anterior cruciate ligament (ACL) ruptures. A hypothesis-driven association study was conducted. In total, 295 control participants, 210 participants with clinically diagnosed Achilles tendinopathy, and 72 participants with Achilles tendon ruptures recruited independently from South Africa and the United Kingdom were genotyped for the prioritized variants. In addition, a cohort including 232 control participants and 234 participants with surgically diagnosed ACL ruptures was also analyzed. Although no associations were observed in the recruited cohorts, the rare rs1800012 TT genotype was associated with decreased ACL injury risk when the results from the current study were combined with that from previously published studies (P = .040, OR: 2.8, 95% CI: 1.0-11.0). In addition, the G-T (rs1107946-rs1800012) inferred haplotype was associated with decreased risk for Achilles tendon ruptures. These results support previous observations and reiterate the heterogeneity of musculoskeletal phenlotypes whereby certain markers may be common to the predisposing profiles while others may be unique.