Non-contact Anterior Cruciate Ligament Injury Epidemiology in Team-Ball Sports: A Systematic Review with Meta-analysis by Sex, Age, Sport, Participation Level, and Exposure Type

Manipulation of task constraints is the most effective motor learning method for reducing risk factors for ACL injury during side-step cutting in both male and female athletes

This study compared the efficacy of linear, non-linear and differential methods on variables related to ACL injury risk of a side-step cutting task in male and female basketball players. Thirty males and thirty females practiced basketball skills in sixty 90-minute sessions across 5 months. Ten players trained in each of the LP, NLP and DL female/male groups separately. Before and after the intervention, each player was tested on a side-step cutting task. A repeated 3 × 2 × 2 factorial ANOVA with repeated measures was performed for each biomechanical variable. Variables (trunk, hip, and knee flexion angle, knee valgus angle, ankle dorsiflexion angle, hip, knee, and ankle ROM, peak VGRF and knee extension/flexion, knee moment and ankle dorsiflexion moment) all revealed significant test by group interactions (P < 0.05) but no significant group by sex interactions (P > 0.05). In both sex, biomechanical changes were better in the NLP, followed by the DL and LP. It is argued that the advantage of the NLP method results from increased exploration of movement solutions induced by the manipulation of task constraints. Therefore, according to the NLP, it is possible to manipulate the constraints without feedback and the model/pattern can keep the athlete away from possible risks.

Functional Return-to-Sport Testing Demonstrates Inconsistency in Predicting Short-Term Outcomes Following Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the relationship between functional testing at the time of return to sport (RTS) and short-term outcomes, such as second anterior cruciate ligament (ACL) tear and return to a preinjury level of sport, among athletes who underwent anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic literature search was performed in MEDLINE, EMBASE, Scopus, and Web of Science to identify studies examining athletes who underwent functional RTS testing and were followed for at least 12 months following ACLR. Studies were screened by 2 reviewers. A standardized template was used to extract information regarding study characteristics, ACLR information, functional test results, and risk factors associated with retear or reduced RTS.

RESULTS

Of the 937 studies identified, 22 met the inclusion criteria. The average time between ACLR and RTS testing was 8.5 months. Single leg hop for distance performance had no association with retear risk in any study and no association with RTS rates in most studies. Quadriceps strength had conflicting results in relation to retear risk, whereas it had no relationship with RTS rates. Rates of reinjury and RTS were similar between patients who passed and did not pass combined hop and strength batteries. Asymmetric knee extension and hip moments, along with increased knee valgus and knee flexion angles, demonstrated increased risk of retear.

CONCLUSIONS

Individual hop and strength tests that are often used in RTS protocols following ACLR may have limited and inconsistent value in predicting ACL reinjury and reduced RTS when used in isolation. Combined hop and strength test batteries also demonstrate low sensitivity and negative predictive value, highlighting conflicting evidence to suggest RTS testing algorithm superiority.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Postural Control During Single-Leg Landing in Female Athletes After Anterior Cruciate Ligament Reconstruction

Background

Secondary anterior cruciate ligament (ACL) injury is a complication of ACL reconstruction (ACLR), which may result from altered neuromuscular control affecting anticipatory postural adjustments (APAs) and compensatory postural adjustments (CPAs) required for maintaining balance during movement. However, it remains unclear how APAs and CPAs differ in single-leg landings post-ACLR compared to healthy subjects.

Purpose

The purpose of this study was to clarify the differences in muscle activities of APAs and CPAs, lower limb kinematics, and kinetics between athletes with a history of ACLR and healthy athletes during single-leg landing.

Study design

Cross-sectional study.

Methods

Eighteen female athletes were recruited and divided into ACLR (n = 9) and control groups (n = 9). The experimental task involved a single-leg landing from a 30 cm box. Joint angles and moments were determined using a 3-dimensional motion analysis system, while muscle activity was assessed using surface electromyography. Analysis intervals were divided into two phases: the APA phase (-150 ms to 50 ms) and the CPA phase (50 ms to 250 ms), with initial contact (0 ms) as the reference point. Muscle activity onset time was defined as the time when the baseline exceeded by the sum of mean values and 2 standard deviations.

Results

No significant differences were observed in muscle activity or onset time between the ACLR and control groups. However, an increased hip external rotation moment was observed during the CPA phase in the ACLR group.

Conclusion

These findings suggest that APAs and CPAs of athletes who returned to sports more than 1 year post-ACLR may be similar. The increased hip external rotation moment in the ACLR group during the CPA phase could represent a specific compensatory strategy to decrease the hip internal rotation angle post-ACLR.

Level of Evidence

III.

Modified Implant Fixation Technique Is an Alternative for Patients with an Anterior Cruciate Ligament Tear in Limited Resource Settings: A Comparison Functional Outcome Study with Polyether Ether Ketone and Bioabsorbable Screws

Background: Anterior cruciate ligament (ACL) injury is one of the most prevalent factors contributing to knee instability worldwide. This study aimed to evaluate modified metal fixation techniques for ACL reconstruction compared to factory-made implants, such as polyether ether ketone (PEEK) screws, bioabsorbable screws, and modified metal implants. Methods: A retrospective cohort analysis was conducted to assess the functional outcomes of ACL using various fixation methods. Patients who underwent arthroscopic ACL reconstruction at several healthcare facilities were included in the study. The functional outcomes were evaluated using the Lysholm Knee Scoring Scale and the International Knee Documentation Committee (IKDC) score questionnaire at 6- and 12 months post-surgery. Statistical analyses, including the Shapiro-Wilk test and analysis of variance, were performed to compare outcomes among the fixation groups. Results: Thirty-three patients who underwent ACL reconstruction surgery with varying distributions across the three fixation groups (modified metal implants, PEEK screws, and bioabsorbable screws) were included in the study. As measured by the Lysholm and IKDC scores at 6- and 12 months post-surgery, the PEEK group demonstrated the highest average scores. Nevertheless, these functional outcomes were not significantly different between the groups (p = 0.140, 0.770, 0.150, and 0.200). These findings align with those of meta-analyses comparing different fixation methods for ACL reconstruction. Conclusions: While acknowledging the small sample size as a limitation, this study suggests that modified metal implants represent viable options for ACL reconstruction. The selection of fixation methods should consider patient characteristics and preferences, emphasizing biomechanical stability and long-term outcomes. Further research is needed to validate these findings and explore their biomechanical properties and cost-effectiveness.

Decreased sagittal slope of the medial tibial spine and deep concavity of the lateral tibial spine are risk factors for noncontact anterior cruciate ligament injury

PURPOSE

This study aimed to assess the relationship between the geometric features of tibial eminence and susceptibility to noncontact anterior cruciate ligament (ACL) injuries.

METHODS

Patients with unilateral noncontact knee injuries between 2015 and 2021 were consecutively enroled in this study. Based on knee magnetic resonance imaging (MRI) and arthroscopic visualisation, patients were categorised into the case group (ACL rupture) and control group (ACL intact). Using MRI, the geometric features of tibial eminence were characterised by measuring the sagittal slopes, depth of concavity and coronal slopes of the inclined surfaces of the tibial spines. Univariate and multivariate logistic regressions were conducted to explore independent associations between quantified geometric indices of tibial eminence and the risk of noncontact ACL injuries.

RESULTS

This study included 187 cases and 199 controls. A decreased sagittal slope of the medial tibial spine (MTSSS) (combined group: odds ratio [OR]: 0.87 [0.82, 0.92], p < 0.001; females: OR: 0.88 [0.80, 0.98], p = 0.020; males: OR: 0.87 [0.81, 0.93], p < 0.001) and an increased depth of concavity in the lateral tibial spine (LTSD) (combined group: OR: 1.51 [1.24, 1.85], p < 0.001; females: OR: 1.65 [1.12, 2.43], p = 0.012; males: OR: 1.44 [1.11, 1.89], p = 0.007) were independent risk factors for noncontact ACL injuries. Moreover, a steeper coronal slope of the inclined surface of the medial tibial spine was a significant predictor of noncontact ACL injuries for males (MTSCS: OR: 1.04 [1.01, 1.08], p = 0.015) but not for females.

CONCLUSION

Geometric features of tibial eminence, particularly a decreased MTSSS and an increased LTSD, were identified as independent risk factors for noncontact ACL injuries. These findings will help clinicians identify individuals at high risk of ACL injury and facilitate the development of targeted prevention strategies.

LEVEL OF EVIDENCE

Level III.

Individualized Technique Feedback for Instant Technique Improvements and Knee Abduction Moment Reductions - A New Approach for 'Sidestepping' ACL Injuries?

Background

Sidestep cutting technique is highly individual and has been shown to influence knee joint loading. However, studies assessing whether individualized technique feedback improves technique and ACL injury-relevant knee joint loads instantly in a sport-specific task are lacking.

Purpose

To determine the instant effects of individualized augmented technique feedback and instructions on technique and the peak external knee abduction moment (pKAM) in a handball-specific sidestep cut. Additionally, to determine the effects of technique modifications on the resultant ground reaction force and its frontal plane moment arm to the knee joint center.

Study Design

Controlled laboratory cohort study.

Methods

Three-dimensional biomechanics of 48 adolescent female handball players were recorded during a handball-specific sidestep cut. Following baseline cuts to each side, leg-specific visual and verbal technique feedback on foot strike angle, knee valgus motion, or vertical impact velocity using a hierarchically organized structure accounting for the variables' association with performance was provided. Subsequently, sidestep cuts were performed again while verbal instructions were provided to guide technique modifications. Combined effects of feedback and instructions on technique and pKAM as well as on the resultant ground reaction force and its frontal plane moment arm to the knee joint center were assessed.

Results

On average, each targeted technique variable improved following feedback and instructions, leading to instant reductions in pKAM of 13.4% to 17.1%. High inter-individual differences in response to feedback-instruction combinations were observed. These differences were evident in both the adherence to instructions and the impact on pKAM and its components.

Conclusion

Most players were able to instantly adapt their technique and decrease ACL injury-relevant knee joint loads through individualized augmented technique feedback, thereby potentially reducing the risk of injury. More research is needed to assess the retention of these adaptations and move towards on-field technique assessments using low-cost equipment.

Level of Evidence

Level 3.

Reported Anterior Cruciate Ligament Injury Incidence in Adolescent Athletes Is Greatest in Female Soccer Players and Athletes Participating in Club Sports: A Systematic Review and Meta-analysis

PURPOSE

To identify the risk of anterior cruciate ligament (ACL) injury in adolescent athletes based on sex, sport, and sport affiliation.

METHODS

A literature search was performed using 3 online databases (PubMed, Cochrane Library, and EMBASE) from database inception to November 2023 per the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies consisted of Level I or II studies reporting on ACL injury exposures in time (hours) or injuries per 1,000 athlete-exposures (AEs) (1 game or practice) in adolescent athletes. Exclusion criteria consisted of non-English studies, case reports, animal/cadaveric studies, and review articles. Methodological quality and bias assessment of the included studies was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. ACL injuries were analyzed and pooled to calculate incidence rates (IRs), per-season risk, and relative risk (RR) based on sex, sport, and sport affiliation (club sport participation vs school sport participation).

RESULTS

A total of 1,389 ACL injuries over 19,134,167 AEs were identified (IR, 0.075; 95% confidence interval [CI], 0.071-0.079). Of these, 670 ACL injuries were reported in female athletes over 7,549,892 AEs (IR, 0.089; 95% CI, 0.087-0.091) with 719 in males over 11,584,275 AEs (IR, 0.062; 95% CI, 0.058-0.067). The greatest RR for ACL injury in females was in soccer (RR, 3.12; 95% CI, 2.58-3.77) for AEs. The greatest per-season risk of ACL injuries reported in female athletes occurred in soccer (1.08%), basketball (1.03%), and gymnastics (1.01%). The greatest per-season risk of ACL injuries reported in male athletes occurred in football (0.82%), lacrosse (0.64%), and soccer (0.35%). Club sport participation, in both AEs (RR, 3.94; 95% CI, 3.19-4.87) and hours of exposure (RR, 1.57; 95% CI, 1.07-2.28), demonstrated an increased risk of ACL injury.

CONCLUSIONS

The risk of ACL injuries was 1.56-fold greater in adolescent female athletes compared with male athletes. The highest-risk sport for females was soccer. Participation in club sports possessed higher rates of injury compared with school sports.

LEVEL OF EVIDENCE

Level II; meta-analysis of Level I and II studies.

Health Benefits of Different Sports: a Systematic Review and Meta-Analysis of Longitudinal and Intervention Studies Including 2.6 Million Adult Participants

BACKGROUND

Several reviews have examined the health benefits of participation in specific sports, such as baseball, cricket, cross-country skiing, cycling, downhill skiing, football, golf, judo, rugby, running and swimming. However, new primary studies on the topic have recently been published, and the respective meta-analytic evidence needs to be updated.

OBJECTIVES

To systematically review, summarise and appraise evidence on physical health benefits of participation in different recreational sports.

METHODS

Searches for journal articles were conducted in PubMed/MEDLINE, Scopus, SpoLit, SPORTDiscus, Sports Medicine & Education Index and Web of Science. We included longitudinal and intervention studies investigating physical health outcomes associated with participation in a given sport among generally healthy adults without disability.

RESULTS

A total of 136 papers from 76 studies conducted among 2.6 million participants were included in the review. Our meta-analyses of available evidence found that: (1) cycling reduces the risk of coronary heart disease by 16% (pooled hazard ratio [HR] = 0.84; 95% confidence interval [CI]: 0.80, 0.89), all-cause mortality by 21% (HR = 0.79; 95% CI: 0.73, 0.84), cancer mortality by 10% (HR = 0.90; 95% CI: 0.85, 0.96) and cardiovascular mortality by 20% (HR = 0.80; 95% CI: 0.74, 0.86); (2) football has favourable effects on body composition, blood lipids, fasting blood glucose, blood pressure, cardiovascular function at rest, cardiorespiratory fitness and bone strength (p < 0.050); (3) handball has favourable effects on body composition and cardiorespiratory fitness (p < 0.050); (4) running reduces the risk of all-cause mortality by 23% (HR = 0.77; 95% CI: 0.70, 0.85), cancer mortality by 20% (HR = 0.80; 95% CI: 0.72, 0.89) and cardiovascular mortality by 27% (HR = 0.73; 95% CI: 0.57, 0.94) and improves body composition, cardiovascular function at rest and cardiorespiratory fitness (p < 0.010); and (5) swimming reduces the risk of all-cause mortality by 24% (HR = 0.76; 95% CI: 0.63, 0.92) and improves body composition and blood lipids (p < 0.010).

CONCLUSIONS

A range of physical health benefits are associated with participation in recreational cycling, football, handball, running and swimming. More studies are needed to enable meta-analyses of health benefits of participation in other sports. PROSPERO registration number CRD42021234839.

Most Anterior Cruciate Ligament Injuries in Professional Athletes Occur Without Contact to the Injured Knee: A Systematic Review of Video Analysis Studies

PURPOSE

To systematically review studies using video analyses to evaluate anterior cruciate ligament (ACL) injury mechanisms in athletes during sport to better understand risk factors and the potential for injury prevention.

METHODS

A literature search was conducted in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines statement using SCOPUS, PubMed, Medline, and the Cochrane Central Register for Controlled Trials from database inception through June 2023. Inclusion criteria included studies reporting on ACL injury mechanisms occurring in athletes based on video analysis. Athlete demographics, injury mechanisms, position of the lower extremity, and activity at the time of injury were recorded.

RESULTS

A total of 13 studies, consisting of 542 athletes, met inclusion criteria. Most athletes competed at the professional level (91%, n = 495/542), with 79% (n = 422/536) of athletes being male. The most common sports were soccer (33%, n = 178/542) and American football (26%, n = 140/542). The most common injury mechanism was noncontact in 42.9% (n = 230/536) of athletes, followed by indirect contact (32.6%, n = 175/536) and direct contact (22.4%, n = 120/536). The most common position of injury was with a planted foot (91.7%, n = 110/120), full or near-full knee extension (84.4%, n = 49/58), and axial loading (81.3%, n = 87/107). Injuries commonly involved a deceleration/shift in momentum (50.4%, n = 123/244) or pivoting maneuver (36.1%, n = 77/213). At the time of injury, the knee commonly fell into valgus (76.8%, n = 225/293) with associated internal (53.5%, n = 46/86) or external tibiofemoral rotation (57.7%, n = 101/175).

CONCLUSIONS

Most ACL injuries, when evaluated by video analysis, involve professional athletes participating in soccer and American football. The most common injury mechanism occurred without contact with the knee in extension during a deceleration or momentum shift, with resultant valgus and rotational force across the knee.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

An Investigation of Running Kinematics with Recovered Anterior Cruciate Ligament Reconstruction on a Treadmill and In-Field Using Inertial Measurement Units: A Preliminary Study

Anterior cruciate ligament reconstruction (ACLR) may affect movement even years after surgery. The purpose of this study was to determine possible interlimb asymmetries due to ACLR when running on a treadmill and in field conditions, with the aim of contributing to the establishment of objective movement assessment in real-world settings; moreover, we aimed to gain knowledge on recovered ACLR as a biomechanical risk factor. Eight subjects with a history of unilateral ACLR 5.4 ± 2.8 years after surgery and eight healthy subjects ran 1 km on a treadmill and 1 km on a concrete track. The ground contact time and triaxial peak tibial accelerations were recorded using inertial measurement units. Interlimb differences within subjects were tested and compared between conditions. There were no significant differences between limbs in the ACLR subjects or in healthy runners for any of the chosen parameters on both running surfaces. However, peak tibial accelerations were higher during field running (p-values < 0.01; Cohen's d effect sizes > 0.8), independent of health status. To minimize limb loading due to higher impacts during field running, this should be considered when choosing a running surface, especially in rehabilitation or when running with a minor injury or health issues.

Recruitment and baseline characteristics of young adults at risk of early-onset knee osteoarthritis after ACL reconstruction in the SUPER-Knee trial

Objectives

The study aims to (1) report the process of recruiting young adults into a secondary knee osteoarthritis prevention randomised controlled trial (RCT) after anterior cruciate ligament reconstruction (ACLR); (2) determine the number of individuals needed to be screened to include one participant (NNS) and (3) report baseline characteristics of randomised participants.

Methods

The SUpervised exercise-therapy and Patient Education Rehabilitation (SUPER)-Knee RCT compares SUPER and minimal intervention for young adults (aged 18-40 years) with ongoing symptoms (ie, mean score of <80/100 from four Knee injury and Osteoarthritis Outcome Score subscales (KOOS4)) 9-36 months post-ACLR. The NNS was calculated as the number of prospective participants screened to enrol one person. At baseline, participants provided medical history, completed questionnaires (demographic, injury/surgery, rehabilitation characteristics) and underwent physical examination.

Results

1044 individuals were screened to identify 567 eligible people, from which 184 participants (63% male) enrolled. The sample of enrolled participants was multicultural (29% born outside Australia; 2% Indigenous Australians). The NNS was 5.7. For randomised participants, mean±SD age was 30±6 years. The mean body mass index was 27.3±5.2 kg/m2, with overweight (43%) and obesity (21%) common. Participants were, on average, 2.3 years post-ACLR. Over half completed <8 months of postoperative rehabilitation, with 56% having concurrent injury/surgery to meniscus and/or cartilage. The most affected KOOS (0=worst, 100=best) subscale was quality of life (mean 43.7±19.1).

Conclusion

Young adults post-ACLR were willing to participate in a secondary osteoarthritis prevention trial. Sample size calculations should be multiplied by at least 5.7 to provide an estimate of the NNS. The SUPER-Knee cohort is ideally positioned to monitor and intervene in the early development and trajectory of osteoarthritis.

Trial registration number

ACTRN12620001164987.

Gender differences in the impact of anatomical factors on non-contact anterior cruciate ligament injuries: a magnetic resonance study

PURPOSE

To identify MRI-detected anatomical risk factors for non-contact anterior cruciate ligament (ACL) injuries across genders.

METHODS

A retrospective analysis was performed on 141 ACL-reconstructed patients (35 females, 106 males) and 142 controls (37 females, 105 males) from January 2020 to April 2022. Inclusion criteria were primary non-contact ACL injuries. The tibial plateau slope, lateral femoral condyle index, Insall-Salvati index, and patellar tendon angle were measured, using binary logistic regression for gender-specific risk evaluation.

RESULTS

Increased lateral tibial plateau slope, reduced intercondylar notch width index, lateral femoral condyle index, and patellar tendon angle correlated with ACL injuries in both genders. The Insall-Salvati index was a significant risk factor in females but not in males.

CONCLUSION

This study identifies the lateral tibial plateau slope, notch width index, lateral femoral condyle index, and patellar tendon angle at near-extension as risk factors for ACL injuries in both genders, with the Insall-Salvati index also implicated in females.

Injury Prevention Programmes Fail to Change Most Lower Limb Kinematics and Kinetics in Female Team Field and Court Sports: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

BACKGROUND

One mechanism by which exercise interventions may be effective in reducing anterior cruciate ligament (ACL) injury risk is through changes in lower limb biomechanics. Understanding how training programmes affect lower-limb kinematics and kinetics may help refine injury prevention programmes.

OBJECTIVE

The aim of this systematic review and meta-analysis was to assess the effect of injury prevention programmes on kinematics and kinetics during tasks related to ACL injury in female team field and court sports.

DATA SOURCES

Five databases were searched in October 2022.

ELIGIBILITY CRITERIA

Randomised controlled trials assessing the effect of injury prevention programmes compared with usual training/no training on lower limb kinematics and kinetics in female team field and court sports were eligible for review.

RESULTS

Sixteen studies were included. A total of 976 female athletes were included. Most of the studies included interventions with multiple components (12/16). Commonly used components were plyometrics (12/16), strength (8/16), and balance/stability (7/16). Thirteen studies had routine training or sham interventions as the control group and three studies had no training. Very low certainty evidence suggests that injury prevention programmes increase knee flexion angles (mean difference = 3.1° [95% confidence interval 0.8-5.5]); however, very low to low certainty evidence suggests no effect on hip flexion angles/moments, knee flexion moments, hip adduction angles/moments, knee adduction angles/moments, hip internal rotation angles/moments, ankle dorsiflexion angles, and ground reaction forces, compared with usual training/no training.

CONCLUSION

Injury prevention programmes may be effective in increasing knee flexion angles during dynamic landing and cutting tasks but may have no effect on other lower limb biomechanical variables. As such, the benefits of injury prevention programmes may be mediated by factors other than altered biomechanics and/or may happen through other biomechanical measures not included in this review.

Jumping into recovery: A systematic review and meta-analysis of discriminatory and responsive force plate parameters in individuals following anterior cruciate ligament reconstruction during countermovement and drop jumps

Purpose

Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post-ACLR during CMJ and/or DJ.

Methods

We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross-sectional papers comparing post-ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist.

Results

Thirty-three studies including 1185 (50.38%) participants post-ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single-leg CMJ, double-leg CMJ, single-leg DJ, and double-leg DJ. Jump height was reduced in both single (mean difference [MD] = -3.13; p < 0.01; 95% confidence interval [CI]: [-4.12, -2.15]) and double-leg (MD = -4.24; p < 0.01; 95% CI: [-5.14, -3.34]) CMJs amongst individuals with ACLR. Similarly, concentric impulse and eccentric/concentric impulse asymmetry could distinguish between ACLR (MD = 3.42; p < 0.01; 95% CI: [2.19, 4.64]) and non-ACLR (MD = 5.82; p < 0.01; 95% CI: [4.80, 6.80]) individuals. In double-leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = -0.10; p = 0.03; 95% CI: [-0.18, -0.01]) but higher in the uninvolved side (MD = 0.15; p < 0.01; 95% CI: [0.10, 0.20]) when compared to controls and demonstrated significant changes between 6 months and 3 years post-ACLR.

Conclusion

This study identified discriminative kinetic parameters when comparing individuals with and without ACLR and also monitored neuromuscular function post-ACLR. Due to heterogeneity, a combination of parameters may be required to better identify functional deficits post-ACLR.

Level of Evidence

Level III.

Increased knee torsional misalignment associated with femoral torsion is related to non-contact anterior cruciate ligament injury: a case-control study

BACKGROUND

Altered axial biomechanics of the knee are recognized as a risk factor for non-contact anterior cruciate ligament (ACL) injury. However, the relationship of knee and segmental torsion to non-contact ACL and combined anterolateral ligament (ALL) injury is unclear. This study aims to determine the relationship of knee and segmental torsion to non-contact ACL injury and to explore their relationship with ALL injuries.

METHODS

We divided 122 patients with arthroscopically confirmed non-contact ACL injuries into an ACL injury group (isolated ACL injury, 63 patients) and an ACL + ALL injury group (ACL combined with ALL injury,59 patients). Additionally, 90 normal patients with similar age, gender and body mass index (BMI) were matched as a control group. The tibial tubercle-trochlear groove (TT-TG) distance, distal femoral torsion (DFT), posterior femoral condylar torsion (PFCT) and proximal tibial torsion (PTT) were measured using magnetic resonance imaging (MRI). We assessed the differences between the groups using an independent samples t test and utilized receiver operating characteristic (ROC) curves to determine the cut-off value for the increased risk of ACL injury.

RESULTS

In patients with ACL injury, the measurements of the TT-TG (11.8 ± 3.1 mm), DFT (7.7° ± 3.5°) and PFCT (3.6° ± 1.3°) were significantly higher compared to the control group (9.1 ± 2.4 mm, 6.3° ± 2.7° and 2.8° ± 1.3°, respectively; P < 0.05), but the PTT did not differ between the two groups. The TT-TG, DFT and PFCT were not significantly larger in patients combined with ALL injury. ROC curve analysis revealed ACL injury is associated with TT-TG, DFT and PFCT.

CONCLUSIONS

Knee torsional alignment is associated with ACL injury, predominantly in the distal femur rather than the proximal tibia. However, its correlation with ALL injury remains unclear. These findings may help identify patients at high risk for non-contact ACL injury and inform the development of targeted prevention and treatment strategies.

Skeletal Maturity Is Associated With Increased Meniscal and Chondral Pathology in Patients Under 21 Years of Age Undergoing Primary Anterior Cruciate Ligament Reconstruction Within 6 Months of Injury

PURPOSE

To compare injury profiles of meniscal and/or chondral injury in skeletally mature (SM) with immature (SI) patients undergoing primary anterior cruciate ligament reconstruction (ACLR).

METHODS

Current Procedural Terminology code 29888 was queried from January 2012 to April 2020. Patients younger than 22 years who underwent primary ACLR within 6 months of injury were included. Exclusion criteria included age older than 22 years, treatment after 6 months, revision ACLR, concurrent osteotomy, or multiligamentous injury. All patients required a minimum 1-year follow-up. Demographics and intraoperative pathology were recorded. Data were analyzed for factors affecting intra-articular injury and stratified by sport.

RESULTS

Of 927 patients (739 SM, 188 SI), the mean age was 16.63 and 14.00 years for the SM and SI cohorts, respectively (P < .001). There were more SM males (51.4%) compared to SI males (81.9%) (P < .001); however, in univariate analysis, sex did not significantly affect the rates of meniscal (P = .519) or chondral injury (P = .961). In total, 887 meniscal injuries were recorded (344 medial, 543 lateral) in 659 patients. SM sustained greater rates of medial meniscal tear (MMT) (P < .001) and underwent higher rates of partial meniscectomy (P = .022). Male sex conferred meniscal injury (95% confidence interval [CI], 0.43-0.81; P = .001). Body mass index prognosticated medial meniscal (95% CI, 1.01-1.06; P = .002) and medial chondral injuries (95% CI, 1.02-1.09; P < .001). Skeletal maturity was a superior predictor of intra-articular pathology than age for all outcomes: MMT (95% CI, 0.00-0.06; P = .002), lateral meniscal tear (95% CI, 0.00-0.75; P = .034), and chondral injury (95% CI, 0.00-0.49; P = .049). In sport subanalysis, soccer anterior cruciate ligament (ACL) injuries were most common (32.6%). Soccer and basketball athletes were more likely SM (P = .016, P = .003 respectively) with increased medial compartment pathology. Football ACL injuries occurred significantly in SI athletes (P = .001) via contact mechanisms (P = .025).

CONCLUSIONS

Skeletal maturity affects the meniscal and chondral injury profile in ACL-injured patients. SM patients have greater risk of sustaining concomitant meniscal injury, while chondral injury profile depends more on the mechanism of injury. Mechanism of injury and skeletal maturity status affect risk of sports-related ACL rupture and ACL-concurrent pathology in young patients. Patient-specific variables influence injury profiles within each sport. Skeletal maturity rather than age predicts concomitant intra-articular injury risk.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Common Injuries in Female Competitive Softball Players

The popularity of softball is rising among female athletes with more than two million players between the ages of 12 and 18 competing per year. As participation rates increase, the frequency of injuries related to softball is on the rise. Softball injuries can differ from baseball injuries, and only a small amount of current literature focuses exclusively on softball injuries. Orthopaedic surgeons need to be prepared to evaluate, diagnose, and treat common injuries sustained while playing softball. The purpose of this study is to investigate the mechanisms of injury that are commonly encountered by female athletes in competitive fast-pitch softball and review current safety initiatives that have been implemented to aide in injury prevention.

Does injury risk increase when youth athletes start to study at a sports high school?

Background/aim

The injury risk is high in adolescent elite athletes. However, little is known about how the injury risk changes when young talented athletes start studying at a sports high school. The primary aim was therefore to explore the risk of injury when the athlete starts to study at a sports high school. A secondary aim was to identify risk factors for injury.

Methods

A total of 489 athletes (age 15-16 years) were followed for 20 weeks, including 10 weeks before and 10 weeks after the athlete had started to study at a sports high school. Substantial injury was monitored in adolescent elite athletes using the Oslo Sports Trauma Research Centre Questionnaire.

Results

The results showed that the mean difference (md) in injury prevalence was significantly (p=0.001) higher across the 10 weeks after school had started (md 3.6; 95% CI 1.5 to 5.8), compared with the 10 weeks before. Female athletes had significantly (p<0.001) higher injury prevalence (md 6.4%; 95% CI 3.0 to 9.8) across the 10 weeks after school had started, whereas male athletes (md 0.9%; 95% CI -1.8 to 3.6) had not (p=0.530). Three significant (p<0.05) risk factors were identified; previous injury within the past 12 months (OR 3.23), higher training volume (OR 0.97) and lower well-being (OR 0.71).

Conclusions

Our results provide supporting evidence for increased injury risk in female adolescent elite athletes after the athletes had started to study at a sports high school.

Biomechanics and situational patterns associated with anterior cruciate ligament injuries in the National Basketball Association (NBA)

OBJECTIVES

Perform a comprehensive video analysis of all anterior cruciate ligament (ACL) injuries in National Basketball Association (NBA) athletes from 2006 to 2022 to determine the associated biomechanics, injury mechanism and game situation.

METHODS

NBA players diagnosed with an ACL tear from 2006 to 2022 were identified and videos of each injury evaluated by two reviewers. Visual evaluation included assessment of joint kinematics at three time points: initial contact of the injured leg with the ground (IC), 33 milliseconds later (IC+33) and 66 milliseconds later (IC+66). Game situation was assessed qualitatively.

RESULTS

Videos of 38 out of 47 (80.9%) ACL tears were obtained. 9 injuries were non-contact, while 29 involved indirect contact. Between IC and IC+33, average knee valgus increased from 5.1° to 12.0° and knee flexion increased from 12.6° to 32.6°. At all time points, the majority of injuries involved trunk tilt and rotation towards the injured leg, hip abduction and neutral foot rotation. The most common game situations for injury included the first step when attacking the basket following picking up the ball (n=13), landing following contact in the air (n=11) and jump stop (n=5).

CONCLUSION

Three major mechanisms predominate ACL tears in NBA players: the first step following picking up the ball when attacking, landing and jump stops. None of the injuries reviewed demonstrated direct contact to the knee, emphasising the importance of body kinematics in this injury pattern. The increase in knee valgus and knee flexion between IC and IC+33 should be noted as a possible precipitant to injury.

Previous Injury and Lower Well-being Increase Injury Risk in Female Adolescent Athletes

Several risk factors for injury have been suggested in female elite athletes. However, there is a lack of prospective studies in young female athletes where multiple risk factors have been studied. The aim of this study was to identify risk factors for injury in female adolescent elite athletes. Substantial injuries were monitored in 222 athletes using the validated Oslo Sports Trauma Research Centre Questionnaire over 20 weeks. Over 20 potential risk factors were explored. Based on a binomial generalized linear mixed model, two significant (p<0.05) risk factors for injury were identified; previous injury within the last 12 months (OR 2.55) and well-being (OR 0.97). An athlete with a previous injury had twice as high a risk of injury (13% vs. 6%) compared to an athlete with no previous injury. Higher perceived well-being was associated with a decreased risk of injury. Based on a prospective design with a large sample of female adolescent elite athletes, investigating over 20 potential risk factors for injury, our results suggest that a previous injury and well-being are risk factors for injury.

Higher age and present injury at the start of the season are risk factors for in-season injury in amateur male and female football players-a prospective cohort study

PURPOSE

To describe the injury prevalence, injury pattern, and potential baseline risk factors for injuries in male and female adolescent and adult amateur football players.

METHODS

This prospective study followed adolescent and adult amateur football players over one season March-October 2020. The study was completed by 462 players (130 men, age 20.0 ± 5.7, 14-46 years) who answered a baseline survey and a weekly web survey during the season. A total of 1456 weekly surveys were registered from males and 5041 from females. Injuries were recorded with the Oslo Sports Trauma Research Center Overuse Injury Questionnaire (OSTRC-O2). Potential baseline risk factors (age, performance of strength/conditioning training, participation in other sports, perceived importance of sporting success, self-rated training and match load, perceived balance between training/match load and recovery, previous/present injury at start of season, and injury beliefs) and their association with injury were analysed with Poisson regressions within each sex.

RESULTS

Males reported 95 injuries (262 injury weeks, weekly prevalence 18.0% (95% CI 16.1-20.1)) and females 350 injuries (1206 injury weeks, weekly prevalence 23.9% (95% CI 22.8-25.1)). Gradual-onset injuries accounted for 57% of the injuries in males and 66% in females. For males, substantial injuries were most common in the hip/groin (weekly prevalence 3.8%), ankle (2.1%), posterior thigh (2.0%), and knee (2.0%); and for females, in the knee (4.3%), ankle (2.5%), and lower leg/Achilles tendon (2.0%). Significant risk factors for injury were higher age (rate ratio males 1.05 per year increase (95% CI 1.02-1.08), females 1.03 (95% CI 1.01-1.05)), and present injury at baseline (males 1.92 (95% CI 1.27-2.89), females 1.58 (95% CI 1.19-2.09)).

CONCLUSION

At any given week, almost one in five male and one in four female amateur football players reported new or ongoing injuries. Hip/groin injuries were more frequent in males, while female players had a higher prevalence of knee injuries. Older players and those with an existing injury at the start of the season were more prone to new injury during the season. Rehabilitation of pre-season injury and complaints are key to reduce the injury burden in amateur football.

LEVEL OF EVIDENCE

Level II. Trial registration number NCT04272047, Clinical trials.

Identifying modifiable risk factors and screening strategies associated with anterior cruciate ligament injury risk in children aged 6 to 13 years: A systematic review

Growing anterior cruciate ligament (ACL) injury incidence is reported in countries across Europe, North America and in Australia for 5-14-year-olds, yet research on injury risk reduction predominantly focuses on populations aged > 13 years. For injury risk reduction, it is crucial to understand (i) which modifiable risk factors are associated with ACL injury in children (6-13 years) and (ii) how these risk factors are assessed. Articles were grouped according to sex/gender and/or maturational/age differences and examined modifiable risk factors during different physical screening tasks. The included articles (n = 40) predominantly examined intrinsic risk factors in girls aged 10-13 years. Factors mechanically linked to increased ACL loading at this age included increased peak knee adductor moments, knee valgus angles, hip and knee extension, and ground reaction forces. Assessment focused on laboratory-based assessments (e.g., motion capture, force plates). This review concluded that modifiable risk factors are present in children aged 6-13 years and that injury risk reduction strategies should be implemented as early as possible regardless of sex/gender. Further, screening strategies need updating to be childhood specific and feasible for the wide community. Additional research on extrinsic risk factors, norm values and children aged 6-9 years could allow for more targeted risk reduction strategies.

Effects of gender and fatigue on strength and activity of gluteus medius muscle during a controlled cutting maneuver in preadolescent athletes

The present study aimed to investigate the effects of gender on hip muscle strength and activity during a controlled cutting maneuver in preadolescent athletes. Fifty-six football and handball preadolescent players participated (35 females and 21 males). Normalized mean activity of the gluteus medius (GM) muscle was measured using surface electromyography during cutting maneuvers in pre-activation and eccentric phases. The stance duration and the strength of hip abductors and external rotators were recorded with a force plate and a handheld dynamometer, respectively. Descriptive statistics and mixed model analysis were used to assess statistical difference (α = 0.05). The results showed that boys activate the GM muscle significantly more than girls during the pre-activation phase (P = 0.022). Boys also demonstrated greater normalized strength of hip external rotation than girls (P = 0.038), but not for hip abduction or duration of stance (P > 0.05). When adjusted for abduction strength, however, boys had significantly shorter stance duration than girls (P = 0.006). It seems that sex-dependent differences are present in preadolescent athletes as observed in the strength of hip external rotator muscles and neuromuscular activity of the GM muscle during a cutting maneuver. Future studies are needed to investigate whether these changes influence risk of lower limb/ACL injury during sport activities.

The effects of different rehabilitation training modalities on isokinetic muscle function and male athletes' psychological status after anterior cruciate ligament reconstructions

BACKGROUND

Previously, researchers reported performance enhancements following long-term plyometric training in athletes with anterior cruciate ligament reconstruction (LCA). However, the effects of combined eccentric and plyometric training on measures of isokinetic strength and psychological statues in male athletes have not been examined yet. Knowledge on the effects of combined eccentric and plyometric training help to better plan and program rehabilitations sessions and thus return-to-sports.

OBJECTIVE

This study sought to compare the effects of three different rehabilitation training programs, eccentric training (ECC), plyometric training (PLYO), or combined eccentric and plyometric training (COMB), on psychological measures (kinesiophobia [TSK-CF], functional knee assessment, knee injury and osteoarthritis outcome score [KOOS], international knee documentation committee 2000 questionnaire [IKDC], and knee flexor and extensor isokinetic muscle performance (peak torque [PT], total work, ratio [R-HQ], and ratio of total work [R-TW]) at different angular velocities post ACL surgery in male elite athletes.

METHODS

Forty elite male athletes from different sports (e.g., athletics, team sports) with ACL reconstruction participated in this study. The study started after a 14-weeks post-surgery rehabilitation program, which was identical for all subjects. After this initial rehabilitation period, athletes were randomly assigned to three experimental groups, ECC (n = 10), PLYO (n = 10), and COMB (n = 10), and a control group (CON: n = 10). Testing was conducted pre- and post-the 6-weeks intervention period and included the TSK-CF, KOOS, and IKDC. Peak torque of the knee extensors/flexors was tested at 90, 180, 240 °/s, after the 6-weeks training program only.

RESULTS

Participants' adherence rate was 100% across all groups and none reported any training or test-related injury. No significant between-group baseline differences (pre-6-weeks intervention) were observed for any of the reported psychological and muscle strength parameters. Significant group-by-time interactions were found for TSK-CF (p = 0.001, d = 2.85), KOOS (p = 0.001, d = 1.31), and IKDC (p = 0.001, d = 1.07). The post-hoc analyses indicated that COMB showed larger pre-post improvements for all psychological variables (p < 0.001, d = 2.95 to 13.15), compared with PLYO, ECC, and CON. Contrast analyses demonstrated that COMB yielded significantly greater improvements compared with CON, PLYO, ECC for all isokinetic parameters at all three angular velocities (all p < 0.001, d = 0.99 to 4.61).

CONCLUSION

The results showed that COMB induced greater gains for measures of psychological status and isokinetic muscle strength compared with single-mode PLYO and ECC in elite male athletes during a post-surgery ACL rehabilitation period. Accordingly, it is recommended to implement COMB as an effective rehabilitation means to improve knee function in male elite athletes.

TRIAL REGISTRATION

This study does not report results related to health care interventions using human participants and therefore it was not prospectively registered.

Boys demonstrate greater knee frontal moments than girls during the impact phase of cutting maneuvers, despite age-related increases in girls

PURPOSE

Anterior cruciate ligament (ACL) injury rate is low among children, but increases during adolescence, especially in girls. Increases in the knee valgus moment within 70 ms of contact with the ground (KFM_0-70) may explain the sex-specific increase in the risk of ACL injury. The purpose of the study was to investigate sex-dependent changes in the KFM_0-70 from pre-adolescence to adolescence during a cutting maneuver (CM).

METHODS

Kinematic and kinetic data during the CM task, performed before and after physical exertion, were recorded using a motion capture system and a force plate. A total of 293 team handball and soccer players, aged 9-12 years, were recruited. A number of those who continued sports participation (n = 103) returned five years later to repeat the test procedure. Three mixed-model analysis of variance (ANOVA) for repeated measures tests were used to determine the effects of sex and age period on the KFM_0-70 (1: with no adjustment, 2: adjusted for repeated measurements, and 3: additionally adjusted with hip and knee joint frontal plane kinematics).

RESULTS

Boys had significantly higher KFM_0-70 than girls at both age periods (p < 0.01 for all models). Girls, not boys, demonstrated significantly increased KFM_0-70 from pre-adolescence to adolescence. Importantly, this was fully explained by kinematic variables.

CONCLUSION

Although the marked increase in KFM_0-70 seen in girls may play a role in their risk of ACL rupture, the higher values demonstrated by boys during CM reflect the complexity of multifactorial biomechanical risk factor analysis. The role of kinematics in mediating the KFM_0-70 provides means for modification of this risk factor, but as boys had higher joint moments, continued investigation into sex-dependent biomechanical risk factors is warranted.

LEVEL OF EVIDENCE

II.

Neuromuscular and Biomechanical Jumping and Landing Deficits in Young Female Handball Players

Neuromuscular and biomechanical imbalances that exist in jumping and landing actions should be examined in order to intervene to decrease the risk of ACL injury. The main aim of this study was to analyse and compare, by chronological age, jumping and landing deficits in young female handball players using the Tuck Jump Assessment (TJA). A secondary aim was to relate the qualitative asymmetry values detected using the TJA to the quantitative asymmetry values detected starting from the single leg countermovement jump (SL-CMJ). Sixty-one young female handball players (age: 14.3 ± 1.5 years) were distributed into three groups: U12, U14 and U16 and performed the TJA test and the single leg countermovement jump (SL-CMJ). The female U12 category players obtained the highest scores in the TJA and there were significant differences between the U12 (12.11 ± 1.97) and U14 (10.89 ± 1.74) categories (p = 0.017; ES = 0.374). In the U12 category, the female players presented larger interlimb asymmetry magnitudes in the SL-CMJ test; they also obtained higher scores in the qualitative criteria of the TJA test that referred to asymmetry (r = 0.43; p = 0.027). The analysis of the jumping and landing pattern using TJA allowed us to identify that the lower extremity valgus at landing, foot contact timing not equal and landing contact noise are the main biomechanical deficits in young female handball players. Furthermore, the asymmetry values assessed qualitatively (TJA) are associated with the asymmetry values assessed quantitatively (difference in jump achieved with each limb in the SL-CMJ test) in younger categories.

Finite Element Analysis and Experimental Validation of the Anterior Cruciate Ligament and Implications for the Injury Mechanism

This study aimed to establish a finite element model that vividly reflected the anterior cruciate ligament (ACL) geometry and investigated the ACL stress distribution under different loading conditions. The ACL’s three-dimensional finite element model was based on a human cadaveric knee. Simulations of three loading conditions (134 N anterior tibial load, 5 Nm external tibial torque, 5 Nm internal tibial torque) on the knee model were performed. Experiments were performed on a knee specimen using a robotic universal force/moment sensor testing system to validate the model. The simulation results of the established model were in good agreement with the experimental results. Under the anterior tibial load, the highest maximal principal stresses (14.884 MPa) were localized at the femoral insertion of the ACL. Under the external and internal tibial torque, the highest maximal principal stresses (0.815 MPa and 0.933 MPa, respectively) were mainly concentrated in the mid-substance of the ACL and near the tibial insertion site, respectively. Combining the location of maximum stress and the location of common clinical ACL rupture, the most dangerous load during ACL injury may be the anterior tibial load. ACL injuries were more frequently loaded by external tibial than internal tibial torque.