The records of 141 consecutive patients with confirmed complete anterior cruciate ligament injuries were reviewed retrospectively. One hundred and sixty-two associated injuries were divided into 25 injury complexes. Isolated injuries to the anterior cruciate ligament occurred in 40 cases (28.4%). Injuries of the medial meniscus occurred in 62 cases (38.2%), while injuries of the lateral meniscus occurred in 37 cases (22.8%). Injuries to the medial collateral ligament complex occurred in 42 cases (25.9%). Injuries to the lateral collateral ligament, posterior deep popliteus-arcuate ligament complex, and posterior cruciate ligament were found to be positively correlated (rho = .81, p = .001, and rho = .77, p = .001, N = 141, respectively). Injuries to the medial collateral ligament and the posterior oblique ligament were likewise positively correlated (rho = .45, p = .001, N = 141).
George A. Arangio and Edward W. Cohen
Michael J. Axe, Katherine Linsay and Lynn Snyder-Mackler
The purpose of this study was to determine whether there was a relationship between knee hyperextension and intra-articular pathology in 100 consecutive patients whose sole ligament injury was an arthroscopically confirmed anterior cruciate ligament (ACL) rupture. Hyperextension of both knees was measured using a supine heel-height measurement of high reliability. There was more articular damage to the total joint, lateral joint, and lateral meniscus in patients who hyperextended than in those who did not. There was more articular damage to the total joint and medial joint in patients who were chronically ACL deficient than in those who were acutely or subacutely ACL deficient. The results demonstrate that individuals with ACL injuries whose knees hyperextend 3 cm or more sustain significantly more joint damage at the time of injury than in those whose knees hyperextend less than 3 cm. This study further defines the role of knee hyperextension in ACL injuries and offers a useful and reliable means of measuring knee hyperextension.
Joseph M. Hart, J. Craig Garrison, Riann Palmieri-Smith, D. Casey Kerrigan and Christopher D. Ingersoll
Lower extremity kinetics while performing a single-leg forward jump landing may help explain gender biased risk for noncontact anterior cruciate ligament injury.
Gender comparison of lower extremity joint angles and moments.
Static groups comparison.
Motion analysis laboratory.
Patients or Other Participants:
8 male and 8 female varsity, collegiate soccer athletes.
5 single-leg landings from a 100cm forward jump.
Main Outcome Measures:
Peak and initial contact external joint moments and joint angles of the ankle, knee, and hip.
At initial heel contact, males exhibited a adduction moment whereas females exhibited a abduction moment at the hip. Females also had significantly less peak hip extension moment and significantly less peak hip internal rotation moment than males had. Females exhibited greater knee adduction and hip internal rotation angles than men did.
When decelerating from a forward jump, gender differences exist in forces acting at the hip.
J. Craig Garrison, Joe M. Hart, Riann M. Palmieri, D. Casey Kerrigan and Christopher D. Ingersoll
Gender differences in muscle activity during landing have been studied as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women.
To compare root-mean-square (RMS) electromyography (EMG) of selected lower extremity muscles at initial contact (IC) and at peak knee internal-rotation (IR) moment in men and women during landing.
Preexperimental design static-group comparison.
16 varsity college soccer players (8 men, 8 women).
Main Outcome Measures:
EMG activity of the gluteus medius, lateral hamstrings, vastus lateralis, and rectus femoris during landing.
When RMS EMG of all muscles was considered simultaneously, no significant differences were detected between genders at IC or at peak knee IR moment.
Male and female college soccer players display similar relative muscle activities of the lower extremity during landing. Gender landing-control parameters might vary depending on the technique used to analyze muscle activity.
Christopher Carcia, Jim Eggen and Sandra Shultz
The influence of hip-muscle function on knee-joint kinematics during landing has been inadequately investigated.
To determine the effect of bilateral hip-abductor fatigue on frontal-plane tibiofemoral landing characteristics and vertical ground-reaction force (vGRF) during the landing phase of a drop jump.
20 recreationally active college-age students.
Isometric bilateral hip-abductor-fatigue protocol.
Main Outcome Measures:
Frontal-plane tibiofemoral landing angle, excursion, and vGRF during landing from a drop jump under prefatigue, postfatigue, and recovery conditions.
After the fatigue protocol, participants landed in a greater valgus orientation than in the prefatigued state. No differences in frontal-plane excursion or vGRF were noted.
Isolated bilateral hip-abductor fatigue alters frontal-plane lower extremity orientation during a double-leg landing. Because an increase in valgus orientation has been observed at or near the time of noncontact anterior cruciate ligament injuries, we recommend improving hip-abductor muscle performance to lessen the risk of such injuries.
Nelson Cortes and James Onate
Clinical assessment tools are needed to identify individual athletes who possess elevated risk for anterior cruciate ligament injury. Existing methods require expensive equipment and the investment of a large amount of time for data processing, which makes them unfeasible for preparticipation screening of a large number of athletes.
To assess the extent of agreement between LESS and the iLESS classifications of jump landing performance and the level of agreement between ratings assigned by a novice evaluator and an expert evaluator.
Ratings of drop-jump landings from 20 video recordings of NCAA Division I collegiate athletes, which were randomly selected from a large database.
The dichotomous iLESS score corresponded to the dichotomous classification of LESS score for 15 of 20 cases rated by the expert evaluator and 17 of 20 cases rated by the novice evaluator. For the iLESS, only 2 scores out of 20 differed between the evaluators.
A high level of agreement was observed between the LESS and iLESS methods for classification of jump- landing performance. Because the iLESS method is inexpensive and efficient, it may prove to be valuable for preparticipation assessment of knee injury risk.
D. Clark Dickin, Emily Johann, He Wang and Jennifer K. Popp
Drop height and fatigue have been shown in isolation to affect landing mechanics and increase the risk of sustaining an anterior cruciate ligament injury. The purpose of this study was to identify the combined effects of drop height and fatigue on landing mechanics in recreationally active females. To assess this, 11 healthy, young adult females performed a series of drop jumps from randomized heights before and following a lower extremity fatiguing protocol. Findings for kinematic results demonstrated that hip flexion decreased at initial contact (P = .003) and maximum hip (P = .005) and knee flexion (P = .001) angles increased with increases in drop height. Kinetic results demonstrated that vertical ground reaction forces and joint moments and powers increased as height increased. Ground reaction forces and maximum knee valgus increased from pre- to postfatigue with interactive effects observed in frontal plane hip angle at impact and peak ankle moment. These results confirm the effects of drop height and fatigue and highlighted interactions between these factors. The differential effect of fatigue as a function of drop heights helps to illustrate potentially risky situations that should be addressed in training and injury prevention programs.
Steven H. Ryder, Robert J. Johnson, Bruce D. Beynnon and Carl F. Ettlinger
Athletes are particularly at risk for anterior cruciate ligament injury, and there is some evidence that female athletes are more at risk than males. The conflicting principles of stability and mobility are at odds within the knee, setting the stage for potentially serious injuries. Some investigators suggest that the size of the intercondylar notch should be used to identify athletes at risk for ACL damage, but more research is required before clinical decisions can be based on notch width measurements. Athletic shoe modifications and artificial playing surfaces may influence the incidence of ACL injures. Functional knee braces appear to have beneficial strain shielding effect on the ACL for anterior directed loads and internal–external torques applied to the tibia, but this effect appears to decrease as the magnitude of these anterior directed loads and torques increases. Ski equipment is often pointed to as a contributing factor in ACL injuries, but there is no evidence that modifications in ski equipment will decrease ACL disruptions. An education program based on recognizing the events that lead to ACL injury in skiing may reduce knee injuries in the future.
Kevin E. Wilk, Christopher A. Arrigo and James R. Andrews
The use of closed kinetic chain exercise has grown in the past several years. Closed kinetic chain exercises for the lower extremity have been firmly established in the literature and have been strongly recommended as an integral part of rehabilitation of the patient with anterior cruciate ligament injury. While the scientific and clinical rationale for using closed kinetic chain exercise for the lower extremity appears obvious, the scientific rationale for using closed kinetic chain exercise for the upper extremity is less clear. The purpose of this manuscript is to discuss the scientific rationale for closed kinetic chain for the upper extremity patient. In addition, exercise drills to enhance dynamic stability of the glenohumeral joint are discussed, and a rationale for using these exercises for specific glenohumeral joint pathologies is provided. The concepts of closed and open kinetic chain as applied to the lower extremity may not apply to the upper extremity due to the unique anatomical and biomechanical features as well as the function of the shoulder. It is recommended that clinicians use both closed kinetic chain and open kinetic chain exercises when treating the shoulder patient.
Michaela Gstöttner, Andreas Neher, Arne Scholtz, Martin Millonig, Sandra Lembert and Christian Raschner
The aim of this study was to evaluate balance abilities and electromyographic (EMG) latency times of the preferred and nonpreferred leg in soccer players. Whereas side differences between the two legs in force, kicking speed, and joint laxity have been demonstrated in athletes in previous studies, no data are so far available on balance differences. Low balance ability is generally associated with an increased risk of ligament injuries, and the detection of a possible asymmetry in balance is important because a bilateral difference may be a contributing factor to injury. Twenty-one amateur soccer players were tested. Two different balance test instruments were used: the Biodex Stability System and the Tetrax System. For the evaluation of muscle latency times, EMGs were recorded by means of the EquiTest system. None of the tests performed in this study revealed statistically significant differences in balance ability between the preferred and the nonpreferred leg. The investigations of balance function and muscle response in amateur soccer players did not reveal significant differences between the preferred and nonpreferred leg in the current study. However, a certain tendency to better balance in the nonpreferred leg was observed.