ACL Research Retreat V

Belt-stabilized handheld dynamometers (HHD) assess hip rate of torque development (RTD) and strength in research and clinical practice. However, the reliability of HHD with push and pull configurations to measure hip muscles RTD and peak torque is unclear. PURPOSE: To determine the intra- and inter-reliability of HHD utilizing push and pull configurations to measure hip abduction and extension during early (0-100 ms) and late (100-200 ms) phases for RTD and peak torque. METHODS: Twenty healthy adults (10 females; Tegner Activity Scale = 4.8 ± 0.8) performed three consecutive trials of maximal isometric contractions of each hip abduction and extension, utilizing an HHD with push and pull configurations by two raters. The average early and late phases RTD and peak torque of hip abduction and extension for each rater were utilized for analysis. Reliability was classified as poor (<0.50), moderate (0.50-0.749), good (0.75-0.90), and excellent (>0.90). RESULTS: Intra-rater reliability of hip abduction with the push configuration was moderate-to-good for both RTD phases (ICC2,1 = 0.61-0.88), while the pull was moderate for early phase RTD (ICC2,1 ≥ 0.59) and moderate-to-good for late phase RTD (ICC2,1 = 0.63-0.75). Peak hip abduction torque had good reliability in both configurations (ICC2,1 ≥ 0.79). Intra-rater reliability of hip extension was moderate-to-good for the early RTD phase (ICC2,1 = 0.72-0.85) and good for the late phase (ICC2,1 ≥ 0.81) in the push configuration, with good-to-excellent in the pull for both phases (ICC2,1 = 0.77-0.91). Peak hip extension torque had moderate-to-excellent reliability for push configuration (ICC2,1 = 0.73-0.92) and excellent for pull (ICC2,1 ≥ 0.91). Inter-rater reliability for hip abduction was moderate in the push configuration (ICC3,k ≥ 0.72) and good in the pull (ICC3,k ≥ 0.78) for both RTD phases, while hip extension showed good reliability in the push (ICC3,k ≥ 0.82) and excellent in the pull (ICC3,k ≥ 0.95) configurations. Peak torque inter-rater reliability was good for hip abduction (ICC3,k ≥ 0.83) and excellent for hip extension (ICC3,k ≥ 0.94) in both configurations. CONCLUSION: HHD with push and pull configurations is a reliable and cost-effective method in clinical settings for assessing RTD and strength of hip abductor and extensor muscle groups in healthy adults.

Greater hamstrings stiffness is associated with less anterior tibial translation during controlled perturbations. However, it is unclear how hamstrings stiffness influences anterior cruciate ligament (ACL) loading mechanisms during dynamic tasks. To evaluate the influence of hamstrings stiffness on landing biomechanics related to ACL injury. Cross-sectional study. Research laboratory. A total of 36 healthy, physically active volunteers (18 men, 18 women; age = 23 ± 3 years, height = 1.8 ± 0.1 m, mass = 73.1 ± 16.6 kg). Hamstrings stiffness was quantified via the damped oscillatory technique. Three-dimensional lower extremity kinematics and kinetics were captured during a double-legged jump-landing task via a 3-dimensional motion-capture system interfaced with a force plate. Landing biomechanics were compared between groups displaying high and low hamstrings stiffness via independent-samples t tests. Hamstrings stiffness was normalized to body mass (N/m·kg(-1)). Peak knee-flexion and -valgus angles, vertical and posterior ground reaction forces, anterior tibial shear force, internal knee-extension and -varus moments, and knee-flexion angles at the instants of each peak kinetic variable were identified during the landing task. Forces were normalized to body weight, whereas moments were normalized to the product of weight and height. Internal knee-varus moment was 3.6 times smaller in the high-stiffness group (t22 = 2.221, P = .02). A trend in the data also indicated that peak anterior tibial shear force was 1.1 times smaller in the high-stiffness group (t22 = 1.537, P = .07). The high-stiffness group also demonstrated greater knee flexion at the instants of peak anterior tibial shear force and internal knee-extension and -varus moments (t22 range = 1.729-2.224, P < .05). Greater hamstrings stiffness was associated with landing biomechanics consistent with less ACL loading and injury risk. Musculotendinous stiffness is a modifiable characteristic; thus exercises that enhance hamstrings stiffness may be important additions to ACL injury-prevention programs.

Understanding the biomechanical risk factors for noncontact anterior cruciate ligament (ACL) injury can inform machine learning models, aid in prevention strategies, and guide rehabilitation protocols, reducing the incidence and burden of these injuries in both athletes and the general population. To determine the biomechanical risk factors associated with noncontact ACL injury and increased knee loading. Systematic review; Level of evidence, 4. A literature search was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Randomized, cohort, case-control, and cross-sectional studies identifying noncontact biomechanical risk factors for ACL injuries published before May 2023 were included in this review. Excluded were studies focused on contact ACL injuries, those focused on biomechanical risk factors postinjury, and those not published in the English language. The authors highlighted biomechanical risk factors not extensively covered in previous reviews, including the toe-in position, increased contralateral pelvic hike, increased hip internal rotation angle, and specific ankle angles. A quantitative overview of the included studies was conducted, highlighting the frequency of each biomechanical factor reported as potentially related to ACL injury or loading risk. A total of 28 studies (2819 athletes) were selected for analysis. The majority of these studies (22/28) were cross-sectional, primarily assessing ACL load indirectly via knee valgus moment or ground-reaction forces, while case-control and cohort studies focused on ACL injury incidence. Overall, 83% (5/6) of the studies assessing upper body biomechanics found that trunk flexion/extension and perturbations affect ACL loading risk. Of studies assessing hip biomechanics, 83% (10/12) showed increased ACL loading or injury risk with increased hip abduction/internal rotation angles. For the foot and ankle, increased toe-in/toe-out landing in 67% of studies (2/3) demonstrated higher stress on the ACL. Knee biomechanics were associated with increased ACL loading in 100% of the respective studies (5/5), with decreased knee flexion angles leading to increased loading. The data demonstrated that factors associated with increased medial knee alignment, sagittal alignment of the trunk, and decreased lateral trunk flexion reduced both knee loading and ACL injury risk. Targeted prevention and detection strategies addressing high-risk biomechanics may reduce injury incidence, underscoring the need for further research to optimize intervention programs.

Objectives:Excessive knee joint laxity may decrease overall joint stability and increase the risk of anterior cruciate ligament (ACL) injury during high risk activities. Despite the frequent clinical use of knee arthrometry, as an accurate and valid method for evaluation of knee laxity, no data exists to correlate instrumented laxity measures and ACL strain during dynamic high-risk activities. The purpose of this study was to evaluate relationships between instrumented anterior knee laxity measurements and ACL strain during simulated bi-pedal landing (as an identified high-risk injurious task). We hypothesized that a strong correlation would be observed between ACL strain and arthrometry displacement, and that specimens with greater anterior knee laxity would demonstrate increased peak ACL strain during landing.Methods:20 cadaveric lower limbs (46±6 years, 10 female and 10 male) were tested using a CompuKT knee arthrometer to measure anterior knee joint laxity. Each specimen was tested under four continuous cycles of A-P shear force (±134 N) applied to the tibial tubercle. To quantify ACL strain, a DVRT displacement transducer was arthroscopically placed on the ACL (AM-bundle), and specimens were retested. Subsequently, bi-pedal landing from 30 cm was simulated on a subset of 14 specimens (45±5 years, 6 female and 8 male) using a novel custom-designed drop-stand. Paired sample t-tests, and a general linear model were used to evaluate changes in joint laxity and ACL strain. Results:During simulated drawer tests, 134 N of applied anterior drawer load produced an average 3.1±1.1 mm peak anterior tibial translation and 4.9±4.3% peak ACL strain. Anterior drawer load was a significant determinant of anterior tibial translation (p<0.0005) and peak ACL strain (p=0.02). A strong correlation (r=0.78, P<0.0005) was observed between anterior tibial translation and ACL strain during simulated drawer tests. Cadaveric simulations of landing produced an average 4070±732 N axial impact load representing the generated ground reaction force during landing following a jump. Simulated landing significantly increased peak anterior tibial translation to 10.4±3.5 mm and peak ACL strain to 6.8+2.8 % (p<0.0005) compared to pre-landing conditions. Impact-induced anterior tibial translation was a significant factor in peak ACL strain (p=0.001). Strong correlations were observed between peak ACL strain during landing and anterior tibial translation quantified by knee arthrometry (Figure 1). Conclusion:This work represents the first cadaveric study to establish a strong correlation between arthrometrically measured anterior knee joint laxity and peak ACL strain during dynamic landing (as a high-risk injurious condition). Experimental findings support the tested hypothesis, as a strong correlation between arthrometry displacement collected during laxity tests and concurrent calculated ACL strain was demonstrated. Instrumented measures of anterior knee laxity were predictive of peak ACL strain during landing, while specimens with greater knee laxity demonstrated higher levels of peak ACL strain during landing. Considering ACL strain as an established quantifiable measure of ACL injury risk, current findings highlight the importance of instrumented anterior knee laxity assessments as a potential indicator of ACL injury risk in addition to its clinical utility in the evaluation of ACL integrity.

Background:Athletes who sustain an anterior cruciate ligament (ACL) injury are morelikely to develop adverse health outcomes, such as knee osteoarthritis, kneepain, and obesity. It is assumed that the long-term consequences of ACLreconstruction are caused by the reconstruction itself. Studies haveobserved that relaxin, a peptide hormone similar in structure to insulin,interferes with the structural integrity of the ACL and elicits long termeffects on bone, joint, muscle, and tendon health. Given the known effectsof relaxin, it is reasonable to wonder if relaxin contributes to thedevelopment of these long-term health outcomes, independently of the ACLinjury.Hypothesis/Purpose:The purpose of this study was to evaluate knee valgus and serum relaxinconcentrations (SRC) in athletes who have and have not sustained an ACLinjury. It was hypothesized that athletes who previously tore their ACLwould have higher SRC and more knee valgus than those who were injuryfree.Methods:Twenty-two female athletes participated. Participants were assigned to one oftwo groups: ACL injury (6.0 ± 3.3 years after surgery, N = 4) and injuryfree (N = 18). Kinematic data were collected at 100 Hz using TheMotionMonitor. Participants performed a single leg squat (SLS), single legcrossover dropdown (SCD), and drop vertical jump (DVJ) at two different timepoints in their menstrual period: pre-ovulatory phase and mid-luteal phase.Blood samples were collected when SRC are measurable (mid-luteal phase), andSRC were determined using a Quantikine Human Relaxin-2 Immunoassay.Results:Independent samples t-tests revealed significant differences between thosewho tore their ACL and those who were injury free in SRC and knee valgusduring the SLS in the mid luteal phase, DVJ in both phases, and SCD in bothphases. Specifically, the participants who tore their ACL had significantlyhigher SRC and more knee valgus than those who did not tear their ACL.Conclusion:These findings suggest that a previous ACL injury could place one at anincreased risk of re-tear and other adverse effects on their joints,muscles, and tendons. Thus, further investigating hormonal risk factorsduring long term monitoring of recovery is needed.

Objectives:The incidence of second anterior cruciate ligament (ACL) injury in the first 12 months after ACL reconstruction (ACLR) and return to sport in a young, active population has been reported to be 15 times greater than a previously uninjured cohort. It is unknown if this high relative rate of injury continues beyond the first year after return to sport following ACLR. The tested hypothesis was that the incidence rate of a subsequent ACL injury in the 2 years following ACLR and return to sports would be less than the incidence rate reported within the first 12 months after return to sport, but greater than the ACL injury incidence rate in an uninjured cohort of young athletes.Methods:Seventy-eight subjects who underwent ACLR and were ready to return to a pivoting/cutting sport (RTS) and 47 controls were prospectively enrolled. Each subject was followed for injury and athletic exposure (AE) data for a 24-month period after return to sport. Twenty-three subjects after ACLR and 4 control subjects suffered an ACL injury during this time. Incidence rate ratios (IRR) were calculated to compare the rates (per 1000 athletic exposures [AEs]) of ACL injury in athletes in the ACLR group and control group. For the ACLR group, similar comparisons were conducted for side of injury by sex.Results:The overall incidence rate of a second ACL injury within 24 months after ACLR and RTS (1.39/1000 AE) was nearly 6 times greater (IRR=5.71, 95% CI: 2.0, 22.7, p=0.0003) than healthy control subjects (0.24/1,000 AE). Female ACLR athletes demonstrated 4 times greater rate of injury within 24 months of RTS (IRR=4.51; 95% CI: 1.5-18.2, p=0.0004) than female controls. Within the ACLR group, there was a trend for female subjects to be over two (RR=2.43, 95% CI: 0.8, 8.6) times more likely to suffer a contralateral injury (1.13/1000 AEs) than an ipsilateral injury (0.47/1000 AEs). Overall, 29.5% of athletes suffered a second ACL injury within 24 months of RTS with 20.5% sustaining a contralateral injury and 9.0% incurring an ipsilateral graft re-tear injury. A higher proportion of females (23.7%) suffered a contralateral injury compared to males (10.5%). Conversely, for ipsilateral injuries, the incidence proportion between females (8.5%) and males (10.5%) were found to be similar.Conclusion:These data support the hypothesis that in the 24 months following ACLR and RTS, patients are at greater risk (nearly 6 times) to suffer a subsequent ACL injury compared to young athletes without a history of ACL injury. Additionally, the contralateral limb of female patients appears to be at greatest risk. These 24 month outcome data, analyzed in conjunction with recent 12 month outcome data which noted a 15 times greater risk of ACL injury compared to healthy control subject, indicate that the greatest risk of second ACL injury after ACLR occurs during the initial 12 months after ACLR and RTS than the second year after RTS.

The study analysed unique data on anterior cruciate ligament (ACL) injuries among German professional female and male team sports over seven consecutive seasons with the aim of identifying sex specific differences regarding ACL injury risk, burden and treatment strategies. This prospective observational open cohort study analysed unique insurance data on all complete ACL ruptures from female and male players with at least one competitive match appearance in the two highest divisions of German professional football. The long-term study covered seven consecutive seasons between 2014/15 and 2020/21 and included complete ACL ruptures registered by clubs or physicians with the German statutory accidental insurance for professional athletes (VBG) as part of occupational accident reporting. In total, 131 out of 2965 female players (4.4%) and 95 out of 2639 male players (3.6%) sustained an ACL injury. Mean ACL injury prevalence in female football was 3.0% (95% confidence interval [CI] 1.8-4.3) with an increasing trend over time. Mean ACL injury prevalence in men's professional football was 1.6% (95% CI 0.8-2.3). The overall match incidence in female players was 0.91 ACL injuries per 1000 h of match exposure (95% CI 0.72-1.11). The overall match incidence in male football was 2.5-fold smaller (0.37 ACL injuries per 1000 h of match exposure (95% CI 0.28-0.47). Almost all ACL injuries (99.2%) were treated surgically. Patellar tendon grafts were used more often in male players compared to female players (p < 0.001). The mean period between the day of an ACL injury and the day of surgery was significant longer in female (median 19 days [interquartile range {IQR} 22]) than in male players (median 6 days (IQR 8, p < 0.001). Overall, female players had significant longer time loss after ACL injury and after ACLR compared to men (p < 0.001). The total secondary ACL injury rate after RTP was 31.7% for female players and 32.1% for male players. Female players were significantly younger at their retirement compared to males (26.7 ± 4.2 vs. 33.5 ± 3.3, p < 0.001). The ACL prevalence and match injury risk is higher in female players compared with males. Moreover, the present study shows an increasing trend for both parameters in German female professional football. One out of three players, irrespective of sex, sustained a second ACL injury over a median follow-up of six years. However, women end their careers earlier than men after an ACL injury, which could understate the actual extent of the second ACL injury rate in women. While sex-specific care would be advisable, access to medical treatment still seems to be limited in women's football. Therefore, the therapeutic and medical framework conditions in women's football should be aligned first. Level II.

Background: A preoperative high-grade pivot-shift phenomenon (2+ and 3+) is often a predictor of inferior knee rotational stability and excessive anterior tibial translation of the lateral compartment (L-ATT) after an anterior cruciate ligament (ACL) injury. Lateral extra-articular tenodesis (LET) has been reported to reduce failure rates and improve knee stability in patients with an ACL injury. However, the effect of LET on knee rotational stability and L-ATT is still not entirely clear in patients with an ACL injury and a high-grade pivot-shift phenomenon. Purpose: To explore the effect of LET on knee rotational stability and L-ATT in patients with an ACL injury and a high-grade pivot-shift phenomenon. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 254 patients who underwent ACL reconstruction (ACLR) between January 2019 and December 2020 were retrospectively reviewed, and 71 patients (43 male and 28 female) with a preoperative high-grade pivot-shift phenomenon were included. Of these, 24 patients who underwent ACLR combined with LET and 47 patients who underwent ACLR alone were categorized as the study and control groups, respectively. Knee stability was evaluated by the KT-1000 arthrometer side-to-side difference and the pivot-shift test, and L-ATT was measured on magnetic resonance imaging. Baseline patient characteristics, preoperative and postoperative knee stability, and preoperative and postoperative L-ATT were compared between the 2 groups. Moreover, the relative risk of a residual pivot-shift phenomenon after ACLR combined with LET versus ACLR alone was calculated. Results: The mean time from injury to surgery in the study group was significantly longer than that in the control group (29.9 ± 54.7 vs 10.1 ± 23.1 months, respectively; P = .035). Other baseline patient characteristics, preoperative knee stability, and preoperative L-ATT showed no significant differences between the groups. At the final follow-up (26.4 ± 4.7 and 28.1 ± 11.0 months for study and control groups, respectively), knee rotational stability (residual pivot-shift phenomenon: 2/24 vs 16/47, respectively; P = .018) and L-ATT (4.6 ± 2.6 vs 6.3 ± 2.6 mm, respectively; P = .010) were superior in the study group compared with the control group. Furthermore, the relative risk of a residual pivot-shift phenomenon was significantly lower in the study group (0.176 [95% CI, 0.037-0.845]; P = .030). Conclusion: ACLR combined with LET was an effective treatment strategy for ACL injuries with a high-grade pivot-shift phenomenon, associated with satisfactory clinical outcomes, significantly improved rotational stability, and reduced L-ATT.

Objectives:Fractures of the tibial spine (TSF) occur as a result of an anterior cruciate ligament (ACL) avulsion fracture from the proximal tibia. Both TSF and ACL injuries are associated with concomitant intraarticular pathology seen on Magnetic Resonance Imaging (MRI) and intraoperatively. In addition, posterior tibial slope (PTS) has been identified as a potential risk factor for ACL injury. The purpose of this study is to describe concomitant injuries seen on MRI and at time of surgery for TSF and ACL patients, and to characterize posterior tibial slope in patients who sustain these injuries. Our hypothesis is that ACL and TSF injuries have similar rates of meniscal injury, and that posterior tibial slope is increased in patients with TSF and ACL injuries compared to matched controls.Methods:Utilizing an institutional review board approved retrospective study, we identified patients under 18 years of age who underwent arthroscopic management of a TSF from December 31st 2008 to December 31st 2021. Exclusion criteria were patients with a concomitant lower extremity fracture or posterior cruciate ligament injuries, poor imaging quality, and incomplete medical records. TSF patients were compared to an age and gender matched cohort of patients who underwent surgery for a mid- substance ACL rupture, and a similar control group. We evaluated concomitant injuries based on radiology and operative reports and measured PTS on radiographs as well as medial (MTS) and lateral (LTS) posterior slope on MRI for all groups. We compared tibial slope amongst the groups using a one- way analysis of variance test, and the Fisher’s exact test was used to compare concomitant injuries between the ACL and TSF groups.Results:85 TSF patients met inclusion criteria, of which 44 had an MRI. There were 41 patients in the ACL group and 44 in the control group. The average age was 11.8 years. Concomitant injuries were identified on MRI in 59.1% of TSF and 51.2% of ACL patients, and intraoperatively in 36.5% of TSF and 37% of ACL patients. The most common concomitant injury was lateral meniscus tears. There was no significant differnce between the TSF and ACL groups in terms of lateral meniscus tears seen on MRI (29.5% TSF vs 31.7 ACL, p=1.0) and seen on arthroscopy (18.2% TSF vs 31.7% ACL, p=0.21). Similarly there were no significant differences between the TSF and ACL group in terms of medial meniscus tears seen on MRI (13.6% vs 17.1%, p = 0.77) and on arthroscopy (9% vs 5%, p=0.19). There was a significant difference between groups when comparing the pivot-shift bone bruise pattern seen on MRI (63.6% TSF vs 90.2% ACL, P= <0.01). There was significantly increased radiographic PTS in the TSF and ACL groups (Radiographs 8.7°+/-3.0° TSF vs 9.5°+/-3.3° ACL vs 6.6°+/-2.3° Control, p= <0.01). This was also seen in the MTS mesured on MRI (MTS 5.3°+/-3.1° TSF vs 4.9°+/-2.7° ACL vs 3.7°+/-2.3° Control p= 0.02). There was no significant difference in LTS between TSF and Controls, but there was between ACL and Controls (LTS 4.1°+/-2.8° TSF vs 6.8°+/- 3.9°ACL vs 4.3°+/- 2.3° Control, p=<0.01).Conclusions:This study is the first to depict tibial slope and bone contusion patterns seen in tibial spine injuries, as well as compare rates of meniscal injury and tibial slope between ACL and control patients. Posterior tibial slope is significantly increased in patients who sustain a TSF or ACL injury, suggesting that it may be a risk factor for injury. Similar rates of concomitant meniscal pathology are seen in both TSF and ACL injured patients, which may reflect similar mechanisms of injury. This also highlights that care must be taken to evaluate for additional pathology when treating TSF and ACL injuries. Future study is needed to determine the role, if any, that tibial slope plays in tibial spine fractures as well as to determine if intraarticular pathology identified on MRI influences longer term patient outcomes.

Anterior cruciate ligament (ACL) injuries are the most common ligament injury of the knee, accounting for between 100,000 and 200,000 injuries among athletes per year. ACL injuries occur via contact and non-contact mechanisms, with the former being more common in males and the later being more common in females. These injuries typically require surgical repair and have relatively high re-rupture rates, resulting in a significant psychological burden for these individuals and long rehabilitation times. Numerous studies have attempted to determine risk factors for ACL rupture, including hormonal, biomechanical, and sport- and gender-specific factors. However, the incidence of ACL injuries continues to rise. Therefore, we performed a systematic review analyzing both ACL injury video analysis studies and studies on athletes who were pre-screened with eventual ACL injury. We investigated biomechanical mechanisms contributing to ACL injury and considered male and female differences. Factors such as hip angle and strength, knee movement, trunk stability, and ankle motion were considered to give a comprehensive, joint by joint analysis of injury risk and possible roles of prevention. Our review demonstrated that poor core stability, landing with heel strike, weak hip abduction strength, and increased knee valgus may contribute to increased ACL injury risk in young athletes.

Medial meniscus ramp lesions (MMRLs), lateral meniscus posterior root tears (LMPRTs), and anterolateral complex injuries (ALCIs) are major secondary stabiliser injuries associated with anterior cruciate ligament (ACL) injuries. This study aimed to investigate the effect of the number of secondary stabiliser injuries on knee instability in ACL injuries. Patients who underwent primary ACL reconstruction between January 2017 and May 2023 were enroled in this study. Exclusion criteria encompassed patients with other ligament injuries, a history of contralateral knee injury, hyperextension, flexion contracture and meniscus injuries other than MMRL or LMPRT. Ultimately, 158 patients (mean age: 25.3 years; 81 males and 77 females) were included in this study, and the presence of MMRL, LMPRT and ALCI was investigated. Patients were categorised into four groups based on the number of ACL and secondary stabiliser injuries: single (isolated ACL injury), dual, triad and tetrad. Subsequently, the groups were compared regarding pivot shift grade, quantitative rotational instability measured using an inertial sensor, and anterior tibial translation (ATT). Secondary stabiliser injuries identified included ALCI 85 (53.8%), MMRL 58 (36.7%) and LMPRT 23 (14.6%). The distribution of patients in the single, dual, triad and tetrad groups was 45 (28.5%), 68 (43.0%), 37 (23.4%) and 8 (5.1%), respectively. High-grade pivot shifts were observed in 33.3% (15 out of 45) of the single group, 63.2% (43 out of 68) of the dual group, 67.6% (25 out of 37) of the triad group, and 100% (8 out of 8) of the tetrad group. Quantitative evaluations using the inertial sensor revealed significantly lower acceleration in the isolated ACL injury group compared to the other groups (p < 0.05). No significant difference was observed in ATT measurements (n.s.). The combination of secondary stabiliser injuries led to higher instability. Therefore, it is important to carefully diagnose these injuries and devise appropriate treatment plans, particularly in cases of high knee instability. Level III diagnostic.

This study aimed to determine if a preseason field-based test battery was prospectively associated with noncontact anterior cruciate ligament (ACL) injury in elite female footballers. In total, 322 elite senior and junior female Australian Rules Football and soccer players had their isometric hip adductor and abductor strength, eccentric knee flexor strength, countermovement jump (CMJ) kinetics, and single-leg hop kinematics assessed during the 2019 preseason. Demographic and injury history details were also collected. Footballers were subsequently followed for 18 months for ACL injury. Fifteen noncontact ACL injuries occurred during the follow-up period. Prior ACL injury (odds ratio [OR], 9.68; 95% confidence interval (95% CI), 2.67-31.46), a lower isometric hip adductor to abductor strength ratio (OR, 1.98; 95% CI, 1.09-3.61), greater CMJ peak take-off force (OR, 1.74; 95% CI, 1.09-3.61), and greater single-leg triple vertical hop average dynamic knee valgus (OR, 1.97; 95% CI, 1.06-3.63) and ipsilateral trunk flexion (OR, 1.60; 95% CI, 1.01-2.55) were independently associated with an increased risk of subsequent ACL injury. A multivariable prediction model consisting of CMJ peak take-off force, dynamic knee valgus, and ACL injury history that was internally validated classified ACL injured from uninjured footballers with 78% total accuracy. Between-leg asymmetry in lower limb strength and CMJ kinetics were not associated with subsequent ACL injury risk. Preseason field-based measures of lower limb muscle strength and biomechanics were associated with future noncontact ACL injury in elite female footballers. These risk factors can be used to guide ACL injury screening practices and inform the design of targeted injury prevention training in elite female footballers.

PurposeTo compare patients with generalised joint hypermobility (GJH) who sustained a second anterior cruciate ligament (ACL) injury with those who did not sustain a second ACL injury, in terms of muscle strength, psychological response and level of knee‐strenuous activity after primary ACL reconstruction. We hypothesised that patients who sustained a second ACL injury would display similar muscle strength symmetry, report similar psychological response and report greater levels of knee‐strenuous activity compared to patients who did not sustain a second ACL injury.MethodsData from a rehabilitation specific registry were extracted. Patients 15–30 years old with GJH, who sustained a second ACL injury after primary ACL reconstruction were matched 1:2 with patients with GJH who did not sustain a second ACL injury. Outcomes were compared at the 10‐week, 4‐, 8‐ and 12‐month follow‐ups after primary ACL reconstruction. Outcomes comprised limb symmetry index and peak torque relative to body weight for quadriceps and hamstrings muscle groups assessed seated isokinetically with a Biodex. In addition, the questionnaires knee self‐efficacy scale18, ACL‐return to sport after injury scale and Tegner activity scale (Tegner) were analysed. All outcome data were analysed with the independent t‐test, except for the Tegner which was analysed with the Mann–Whitney U‐test.ResultsThirty‐two patients sustained a second ACL injury and were matched with 64 patients who did not. The mean age at time of ACL reconstruction was 19 ± 3 years, and 58 (60%) were female. There were no differences in muscle strength between groups at any follow‐up. At the 8‐month follow‐up, patients with a second ACL injury reported higher on ACL‐return to sport after Injury (65.6 ± 17.9 vs. 53.5 ± 17.3, p = 0.006), and participated in gknee‐strenuous activity (median Tegner 5.0, interquartile range [IQR]: 3.0 versus 4.0, IQR: 4.0, p = 0.046) compared to patients without a second ACL injury.ConclusionPatients with GJH who sustained a second ACL injury reported greater confidence, lower negative emotions, and lesser risk appraisal towards return to sport, and reported greater levels of knee‐strenuous activity at 8 months after primary ACL reconstruction compared to matched patients who did not sustain a second ACL injury. These findings might suggest that patients who report greater psychological readiness to RTS, that is, greater confidence, lower negative emotions and lesser risk appraisal, at 8 months, need more cautious guidance when increasing knee‐strenuous activity.Level of EvidenceLevel IV, cross‐sectional study.

Anterior cruciate ligament (ACL) injury among professional footballers represents a career-threatening injury with a high burden for athletes and teams. Debated issues in professional footballers after ACL reconstruction (ACLR) include time to return to play (RTP), level of play after surgery, and incidence and timing of sustaining a second ACL injury. To analyze RTP and performance 2 seasons after surgery of professional footballers who underwent ACLR, to evaluate factors influencing the timing of RTP and second injury risk, and to assess the level of RTP and performance after surgery. Case series; Level of evidence, 4. All professional male footballers who underwent ACLR using a hamstrings graft with or without a lateral extra-articular procedure at a single institution between 2002 and 2013 were retrospectively included. Demographic and intraoperative findings were extracted from the medical records. Data regarding the number of matches played in 5 seasons (injury season, the 2 seasons before, and the 2 seasons after the injury), the level of play in those 5 seasons, the time to return to the first official match, and reinjuries were extracted from publicly available databases, and patients were contacted to confirm. Univariate and multivariate analyses were conducted to identify factors influencing RTP and risk factors for second ACL injury. A total of 58 primary ACLRs were included; 20 (34.5%) participated in the first division (Serie A). RTP was 96.6% (56/58) after a mean of 6.4 ± 2.3 months, and return to match occurred after a mean of 7.5 ± 3.3 months. Patients without meniscal injury had a faster RTP (5.6 ± 1.6 months; P = .0016), while athletes with cartilage injury showed a longer time to RTP (10.2 ± 3.7 months; P = .0001) and resulted as a predictor for longer RTP (+4.4 months; P = .0047).In the second season after an ACL injury, 23% of footballers participated in a lower division with respect to the injury season, playing a mean of 20 ± 11 matches, with 65% of them participating in >20 games. The second injury rate was 15.8% (9 patients). The ipsilateral reoperation rate, including ACL revisions, was 28.1%. Additionally, returning to competitive play within 5 months of surgery was a significant predictor of a second ACL injury. Almost all patients returned to play after ACLR using hamstrings graft with over-the-top techniques, typically regaining preinjury performance by the second season after the injury. RTP time was shorter for isolated ACL injuries and longer when associated with meniscal or cartilage injury. Given the high risk of a second ACL injury on either knee and the high reoperation rate, RTP before 5 months should be discouraged, particularly in athletes <21 years.

In order to solve the problem of the difference in the diagnostic effect of different sequences of magnetic resonance imaging (MRI) examinations for anterior and posterior cruciate ligament injuries, the author proposes an MRI rehabilitation method to relieve anterior cruciate ligament injury in dancers. This method retrospectively analyzed the clinical data of 60 patients with knee anterior and posterior cruciate ligament injuries in our hospital, and all patients were diagnosed with knee anterior and posterior cruciate ligament injuries. All patients underwent MRI 3D sequence and 2D sequence examination successively to compare anatomical measurements. This study aimed at comparing the measurements of the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) between the two examination sequences; comparing the diagnosis; comparing the grading and judgment of the anterior and posterior cruciate ligament injuries of the knee joint between the two inspection sequences; and comparing the diagnostic coincidence rates of the two examination sequences in the complete tear of the anterior and posterior cruciate ligaments of the knee. Experimental results show that, in terms of PCL and ACL, the angle, thickness, and length of two-dimensional MRI examination were significantly different from those of MRI examination and anatomical measurement (P < 0.05); for PCL and ACL, the angle, thickness, and length of 3D MRI were not significantly different from anatomical measurements (P > 0.05). The diagnostic accuracy of 2D MRI was 83.33%, which was lower than 95.00% of 3D MRI (P < 0.05). There was no significant difference in the grading of anterior and posterior cruciate ligament injuries between the two examination sequences (P > 0.05). The diagnostic coincidence rates of 3D MRI and 2D MRI for complete tear of the anterior and posterior cruciate ligaments were 95.55% and 80.00%, respectively (P < 0.05). In conclusion, three-dimensional MRI examination can obtain higher diagnostic value for patients with knee joint anterior and posterior cruciate ligament injury.