Youth Sports Anterior Cruciate Ligament and Knee Injury Epidemiology: Who Is Getting Injured? In What Sports? When?

Football has one of the highest injury rates of all team sports given the contact nature. There are continued efforts to optimize athlete safety. Pediatric football players are inexperienced and need to be educated on proper techniques to reduce the risk of minor and catastrophic injury. Comprehensive player safety and training programs are in development and being implemented in youth programs to improve coaching methods and player technique. Rule changes are implemented by organizing bodies to help officials educate and reduce the risk of injury. Musculoskeletal injuries occur in all sports. Football is unique in that the skills, body type, and forces sustained by the athlete are unique to the position played. Surgical, rehabilitation techniques, and return-to-sport are progressive in nature and require position-specific considerations.

To analyze the rates of graft ruptures and growth disorders, the level of return to sport, and the clinical results of 2 lateral extra-articular procedures in growing children.

This study was a retrospective, single-center study of patients undergoing anterior cruciate ligament (ACL) surgery combined with 2 different lateral extra-articular procedures (anatomic reconstruction with a gracilis graft or modified Lemaire technique with a strip of fascia lata). The measurements of side-to-side anterior laxity and pivot shift were performed preoperatively and at the last follow-up. The sports level and the complications rate were assessed. The minimal clinically important differences (MCID) and patient acceptable symptoms state threshold scores were calculated.

Thirty-nine patients (40 ACLs) were included (20 anatomic and 20 modified Lemaire) at an average follow-up of 57 months ± 10 [42-74]. One patient (2.5%) was lost to follow-up. The mean age at surgery was 13.8 ± 1.4 years old [9.8; 16.5]. One graft failure was reported (2.6% [0.06-13.5]) at 35.6 months after surgery. Two cases (5.4%) of femoral overgrowth were observed, and one of them required distal femoral epiphysiodesis. Ninety-two percent of the patients returned to sports. At the final follow-up, side-to-side anterior laxity was significantly improved, and no residual pivot shift was recorded in 95% of patients. Eighty-nine percent of the patients presented a Pedi-International Knee Documentation Committee score greater than the MCID postoperatively, and 77% presented a Lysholm score greater than the MCID.

This series of ACL reconstructions combined with 2 different lateral extra-articular procedures in skeletally immature patients demonstrated promising findings. The low rate of observed complications, including graft rupture and growth disturbance, is encouraging, but the small study population and lack of comparative group precludes reliable conclusions.

IV, therapeutic case series.

This study aimed to validate a simple dynamic model of single-leg drop-landing to develop a methodological foundation for investigating mechanistic causes of anterior cruciate ligament (ACL) injury and to explore mechanical associations between knee valgus torque and landing kinematics that are considered clinically as a high-risk landing posture for the injury. A triple-inverted-pendulum model in three-dimensional space, composed of rigid-links of head-arms-trunk (HAT), thigh and shank, was employed. We derived causal relationships that can predict post-impact kinetics, including impact ground reaction forces (GRFs) and corresponding knee joint torques from a given body-kinematics immediately before impact, based on an assumption of a completely inelastic collision between a landing foot (the distal end-point of the shank in the model) and the ground. The concordance correlation coefficient (CCC) analysis revealed that our model can achieve an acceptable agreement between experimentally measured and model-predicted impact GRFs and corresponding knee joint torques. The $95\%$ one-tailed lower confidence limit of CCC of vertical, mediolateral GRFs and the varus/valgus torque were $0.665>{\rho }_{c,a}=0.643,0.786>{\rho }_{c,a}=0.758$ and $0.531>{\rho }_{c,a}=0.508$, respectively, for the least acceptable values ${\rho }_{c,a}$. Using this model, effects of three types of hypothetical pre-impact kinematics with modulated (i) medial/lateral leaning HAT angle, (ii) forward/backward HAT tilt-angle, and (iii) knee flexion/extension angle on the impact GRF and corresponding knee joint torque were evaluated. We showed that the smaller knee flexion and the greater HAT leaning toward the landing-limb-side, the larger the knee valgus torque is generated, as a mechanical consequence between the specific pre-impact kinematics and the knee loading associated with the risk of ACL injury. Further exploration of hypothetical kinematics using the model in the future work might contribute to identifying the risky landing kinematics beyond experimental limitations.

This chapter discusses the importance of neuromuscular training (NMT) programs consisting of both plyometric and strengthening exercises to maximize proximal muscle strength and decrease anterior cruciate ligament (ACL) injury rate in at-risk populations. Necessary components of a successful NMT program, such as target populations, frequency of training sessions, compliance, and feedback, are discussed. In order to prevent ACL injuries and future cases of osteoarthritis and total knee replacements, physicians, coaches, parents, and athletes should encourage implementation of ACL injury prevention programs in all athletes who are involved in sports with a high risk of ACL injury.

Peu de travaux de la littérature se sont intéressés à la ligamentisation des greffes de LCA pédiatriques. L’objectif de cette étude était de comparer l’aspect IRM des greffes de LCA faites dans une population à physe ouverte aux LCA d’une population d’adolescents et de rechercher si le signal IRM à 6 mois des plasties était prédictif d’une rerupture. Notre hypothèse était que la ligamentisation, était un processus évolutif et lent.

Il s’agissait d’une étude prospective, multicentrique de 100 plasties (7 à 16 ans) du LCA (tendon quadricipital, ischio-jambiers, facia lata) dont 65 plasties non rompues ont eu une ou plusieurs IRM postopératoires à partir du 6^e mois et jusqu’à 2 ans, 7 patients dont la plastie s’était rompue après les IRM ainsi que 20 IRM de LCA normaux d’adolescents (15 à 18 ans) ont également été étudiées. Vingt-huit patients n’ont pas eu d’IRM de contrôle. Pour chaque IRM, le Signal/Noise Quotient (SNQ) a été calculé au niveau de 3 zones différentes du LCA (proximal, moyen, distal) et les grades (I à IV) de Howell intra-articulaire et intratibial ont également été évalués. Les tests du Chi² de Mantel-Haenszel, Wilcoxon signed rank test et de Student ont été réalisés. Les coefficients de correspondance intra-observateur de Lin ont été calculés.

Pour les LCA normaux, il existait une différence significative de SNQ entre les 3 zones et une majorité de Howell III (55 % de Howell III, 25 % de Howell II et 20 % de Howell I). Pour les greffes en continuité, il existait une amélioration significative des SNQ entre 6 et 12 mois et entre 6 et 24 mois, il n’y avait, par contre, aucune différence de SNQ entre les 3 zones quel que soit le délai postopératoire. Le Howell intra-articulaire s’améliorait de manière significative entre 6 et 24 mois et entre 12 et 24 mois ; le Howell intratibial s’améliorait significativement seulement entre 12 et 24 mois. Il n’a été retrouvé aucune différence significative entre les greffes continues de LCA et les re-reruptures, il n’a pas non plus été retrouvé de différence entre les différents types de greffons.

Il existait une grande inhomogénéité des SNQ et du Howell des LCA normaux. Le SNQ et le Howell des greffes s’amélioraient jusqu’à 2 ans, sans restituer l’inhomogénéité du LCA normal, la greffe étant beaucoup plus homogène. Le signal et l’aspect de la greffe de LCA et du LCA normal étaient très différents et le signal IRM à 6 mois n’était pas prédictif de rerupture.

III, étude prospective.

There is little published information on the ligamentization of pediatric anterior cruciate ligament (ACL) grafts. The aims of our study were to compare the MRI appearance of ACL grafts performed in a population with open growth plates to normal ACLs in adolescents and to determine whether the MRI signal in the grafts at 6 months could predict a retear. We hypothesized that ligamentization was a slow, gradual process.

This was a prospective multicenter study of 100 ACL grafts (quadriceps tendon, hamstring tendon, fascia lata) in children 7 to 16 years of age. Of these, 65 intact grafts underwent one or more MRI examinations between 6 months and 2 years postoperative. MRI images were also analyzed in 7 patients who suffered a retear and in the intact ACL of 20 adolescents (15 to 18 years of age). The other 28 patients did not undergo an MRI during the postoperative phase. For each MRI, the signal-to-noise quotient (SNQ) was calculated in three different areas in the ACL (proximal, middle, distal) along with the Howell intra-articular and intra-tibial grades from I to IV. The Mantel-Haenszel Chi-square, Wilcoxon signed-rank test and Student's t-test were used to compare groups. The Lin concordance correlation coefficients were calculated for inter-rater consistency.

There was a difference in the SNQ between the three zones of a normal ACL. Most were Howell grade III (55% Howell III, 25% Howell II and 20% Howell I). For intact grafts, the SNQ improved significantly between 6 and 12 months and between 6 and 24 months. There was no difference in the SNQ between the three zones independent of the postoperative time point. The intra-articular Howell grade improved significantly between 6 and 24 months and between 12 and 24 months. The intra-tibial Howell grade improved significantly between 12 and 24 months. There were no significant differences between patients with intact grafts and those who suffered a retear. There were no differences between the various types of grafts used.

Normal ACLs in adolescents have inhomogeneous SNQ and Howell grades. The SNQ and Howell grades in ACL grafts are more homogeneous and continue to improve out to 2 years, but do not reach that of a normal ACL. The signal and appearance of an ACL graft and normal ACL are very different, and the MRI signal at 6 months postoperative is not predictive of retear.

III, prospective study.