Search Results

You are looking at 91 - 100 of 369 items for :

  • "anterior cruciate ligament" x
Clear All
Restricted access

Alasdair R. Dempsey, Bruce C. Elliott, Bridget J. Munro, Julie R. Steele and David G. Lloyd

Anterior cruciate ligament (ACL) injuries are costly. Sidestep technique training reduces knee moments that load the ACL. This study examined whether landing technique training alters knee moments. Nineteen team sport athletes completed the study. Motion analysis and ground reaction forces were recorded before and after 6 weeks of technique modification. An inverse dynamic model was used to calculate three-dimensional knee loading. Pre- and postintervention scores were compared using paired t tests. Maximal knee flexion angle during landing was increased following training. There was no change in valgus or flexion moments, but an increase in peak internal rotation moment. This increase in internal rotation moment may increase the risk of ACL injury. However, the increased angle at which the peak internal rotation moment occurred at follow up may mitigate any increase in injury risk by reducing load transmission.

Restricted access

J. Craig Garrison, Joe M. Hart, Riann M. Palmieri, D. Casey Kerrigan and Christopher D. Ingersoll

Context:

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.

Objective:

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.

Design:

Preexperimental design static-group comparison.

Setting:

Motion-analysis laboratory.

Participants:

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.

Results:

When RMS EMG of all muscles was considered simultaneously, no significant differences were detected between genders at IC or at peak knee IR moment.

Conclusion:

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.

Restricted access

Oscar Martel, Juan F. Cárdenes, Gerardo Garcés and José A. Carta

Anterior cruciate ligament (ACL) reconstruction is one of the most important aspects of knee surgery. For this purpose, several fixation devices have been developed, although the interference screw is the most frequently used. The most typical biomechanical test of these devices consists of placing them in a testing machine and subjecting them to a pull-out test. However, insufficient attention has been paid to the influence of the displacement test rate on the mechanical properties of the fixation system. The aim of this study is to compare the influence of the crosshead rate in the biomechanical test of two different devices for the fixation of ACL tendon grafts. One hundred in vitro tests were performed using porcine tibiae and bovine tendons. The fixation devices used were (1) an interference screw and (2) a new expansion device. All ACL reconstructions were subjected to pull-out test to failure. Five crosshead rates were employed in a range from 30 mm/min to 4000 mm/min. Statistical analyses of the results show that, for the two devices, the rate has a significant effect on both maximum force and stiffness. Moreover, the new expansion device showed lesser dependency on the crosshead rate than the interference screw.

Restricted access

Christopher J. Durall, Thomas W. Kernozek, Melissa Kersten, Maria Nitz, Jonathan Setz and Sara Beck

Context:

Impaired postural control in single-limb stance and aberrant drop-landing mechanics have been implicated separately as risk factors for noncontact anterior cruciate ligament (ACL) injury, but associations between these variables has not been reported.

Objective:

To determine whether there are associations between single-limb postural control and drop-landing mechanics.

Setting:

University motion-analysis laboratory.

Design:

Single-leg-landing kinematic and kinetic data were collected after participants dropped from a hang bar. Postural-control variables COP excursion and velocity were assessed during single-leg barefoot standing on a force platform.

Participants:

A convenience sample of 24 healthy women.

Main Outcome Measures:

Pearson product–moment correlation coefficients.

Results:

Strong associations were measured between maximal knee-abduction moment and COP excursion (r = .529, P = .003) and average COP velocity (r = .529, P = .003). Strong inverse associations were measured between minimum hip-flexion angle and COP excursion (r = −.521, P = .003) and average COP velocity (r = −.519, P = .003).

Conclusions:

Participants with decreased postural control had higher knee-abduction moments and a more extended hip on landing, which have been implicated separately as risk factors for ACL injury. A longitudinal prospective analysis is needed to determine whether force-platform postural-control measures can identify athletes at risk for ACL injury.

Restricted access

Christopher Carcia, Jim Eggen and Sandra Shultz

Context:

The influence of hip-muscle function on knee-joint kinematics during landing has been inadequately investigated.

Objective:

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.

Design:

Experimental, pretest–posttest.

Setting:

Research laboratory.

Participants:

20 recreationally active college-age students.

Intervention:

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.

Results:

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.

Conclusions:

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.

Restricted access

Gulcan Harput, H. Erkan Kilinc, Hamza Ozer, Gul Baltaci and Carl G. Mattacola

Context:

There is lack of information related to quadriceps and hamstring strength recovery during the early period of rehabilitation after anterior cruciate ligament reconstruction (ACLR) using hamstring-tendon graft (HTG).

Objective:

To investigate quadriceps and hamstring isometric strength at 4-, 8-, and 12-wk time points after ACLR and to document the strength changes of these muscles over time.

Design:

Longitudinal study.

Participants:

24 patients (age 28.1 ± 8.1 y) who underwent unilateral single-bundle anatomic ACLR with 4-strand semitendinosus and gracilis tendon graft.

Main Outcome Measures:

The isometric strength of quadriceps and hamstring muscles was measured on an isokinetic dynamometer at a 60° knee-flexion angle 4, 8, and 12 wk after surgery.

Results:

Quadriceps and hamstring strength significantly increased over time for both the involved limb (quadriceps F 2,46 = 58.3, P < .001; hamstring F 2,46 = 35.7, P < .001) and uninvolved limb (quadriceps F 2,46 = 17.9, P < .001; hamstring F 2,46 = 56.9, P = .001). Quadriceps and hamstring indexes significantly changed from 4 wk (QI 57.9, HI 54.4) to 8 wk (QI 78.8, HI 69.9) and from 8 wk to 12 wk (QI 82, HI 75.7) (P < .001); however, there was no difference between indexes at the 12-wk time point (P = .17).

Conclusions:

The results of this study serve as a reference for clinicians while directing a rehabilitation protocol for HTG ACLR patients to better appreciate expected strength changes of the muscles in the early phase of recovery.

Restricted access

Julie P. Burland, Adam S. Lepley, Marc Cormier, Lindsay J. DiStefano and Lindsey K. Lepley

Protracted deficits in knee function after anterior cruciate ligament reconstruction (ACLR) are commonly attributed to the extensive neural alterations that are observed after injury. 1 – 4 Notably, these widespread neural alterations impede the ability of targeted exercises to efficiently

Restricted access

Mutlu Cug, Erik A. Wikstrom, Bahman Golshaei and Sadettin Kirazci

Context:

Both female athletes’ participation in soccer and associated injuries have greatly increased in recent years. One issue is the 2–9 times greater incidence of noncontact anterior cruciate ligament (ACL) injuries in female athletes relative to male athletes in comparable sports. Several factors such as limb dominance and sporting history have been proposed to play a role in ACL incidence rates between male and female athletes. However, evidence about the effects of these factors and how they interact with sex is mixed, and thus no consensus exists.

Objective:

To quantify the effects of sports participation, limb dominance, and sex on dynamic postural control and knee-joint proprioception.

Design:

Cross-sectional study.

Setting:

University research laboratory.

Participants:

19 male soccer players, 17 female soccer players, 19 sedentary men, and 18 sedentary women.

Intervention:

Joint-position sense was tested using reproduction of passive positioning on a Biodex isokinetic dynamometer (30°, 45°, and 60° from 90° of knee flexion). Three Star Excursion Balance Test directions were used to assess dynamic postural control.

Main Outcome Measure:

Normalized reach distance (% of leg length) in the anterior, posteromedial, and posterolateral directions on each leg quantified dynamic postural control. Average absolute error and constant error for both limbs quantified joint-position sense.

Results:

Posteromedial reach distance was significantly better in soccer players than sedentary individuals (P = .006). Anterior reach distance was significantly better (P = .04) in sedentary individuals than soccer players. No limb-dominance or sex differences were identified for dynamic postural control, and no differences in absolute- or constant-error scores were identified.

Conclusion:

Sporting history has a direction-specific impact on dynamic postural control. Sporting history, sex, and limb dominance do not influence knee-joint proprioception when tested in an open kinetic chain using passive repositioning.

Restricted access

James Onate, Nelson Cortes, Cailee Welch and Bonnie Van Lunen

Context:

A clinical assessment tool that would allow for efficient large-group screening is needed to identify individuals potentially at risk for anterior cruciate ligament (ACL) injury.

Objective:

To assess the criterion validity of a jumplanding assessment tool compared with 3-dimensional (3D) motion analysis and evaluate interrater reliability across an expert vs novice rater using the Landing Error Scoring System (LESS).

Design:

Validity protocol.

Setting:

Controlled, laboratory.

Participants:

Nineteen female (age 19.58 ± .84 y, height 1.67 ± .05 m, mass 63.66 ± 10.11 kg) college soccer athletes volunteered.

Main Outcome Measurement:

Interrater reliability between expert rater (5 y LESS experience) vs novice rater (no LESS experience). LESS scores across 13 items and total score. 3D lower extremity kinematics were reduced to dichotomous values to match LESS items.

Interventions:

Participants performed drop-box landings from a 30-cm height with standard video-camera and 3D kinematic assessment.

Results:

Intrarater item reliability, assessed by kappa correlation, between novice and experienced LESS raters ranged from moderate to excellent (κ = .459–.875). Overall LESS score, assessed by intraclass correlation coefficient, was excellent (ICC2,1 = .835, P < .001). Statistically significant phi correlation (P < .05) was found between rater and 3D scores for knee-valgus range of motion; however, percent agreement between expert rater and 3D scores revealed excellent agreement (range of 84–100%) for ankle flexion at initial contact, knee-flexion range of motion, trunk flexion at maximum knee flexion, and foot position at initial contact for both external and internal rotation of tibia. Moderate agreement was found between rater and 3D scores for trunk flexion at initial contact, stance width less than shoulder width, knee valgus at initial contact, and knee-valgus range of motion.

Conclusions:

Our findings support moderate to excellent validity and excellent expert vs novice interrater reliability of the LESS to accurately assess 3D kinematic motion patterns. Future research should evaluate the efficacy of the LESS to assess individuals at risk for ACL injury.

Restricted access

Kristin D. Morgan

Over 250,000 individuals suffer an anterior cruciate ligament injury in the United States annually, resulting in reconstructive surgery and extensive rehabilitation with the purpose of restoring joint stability and muscle strength to previous functional levels. 1 – 3 The limb symmetry index, which