The first video-based study in Pediatrics

Knee mechanics during planned and unplanned sidestepping: a systematic review and meta-analysis

BACKGROUND

Knee joint mechanics during sidestepping are associated with anterior cruciate ligament injury. Unplanned sidestepping more closely emulates game scenarios when compared with planned sidestepping by limiting decision time, increasing knee loading and challenging the integrity of soft-tissue structures in the knee. It is important to quantify the loads that may challenge the integrity of the knee during planned and unplanned sidestepping.

OBJECTIVE

Our objective was to review literature on knee mechanics during planned and unplanned phases of sidestepping.

DATA SOURCES

PubMed, CINAHL, MEDLINE (EBSCO), SPORTDiscus and Web of Science were searched using the terms knee mechanics OR knee kine*, AND plan*, unplan*, anticipat*, unanticipat*, side*, cut* or chang*.

STUDY SELECTION

A systematic approach was used to evaluate 4,629 records. Records were excluded when not available in English, only available in abstract of conference proceedings, not involving a change-of-direction sidestep, not comparing planned and unplanned or maintaining a running velocity greater than 2 m s(−1).

DATA EXTRACTION

Included studies were evaluated independently by two authors using a custom-designed methodological quality assessment derived from the Physiotherapy Evidence Database (PEDro) scale and then confirmed by a third author.

DATA SYNTHESIS

Only six studies met the inclusion criteria and were retained for meta-analysis. Magnitude-based inferences were used to assess the standardised effect of the differences between planned and unplanned sidestepping. Knee angles and knee moments were extracted and reported for flexion/extension, abduction/adduction and internal/external rotation for initial contact, weight acceptance, peak push-off and final push-off phases of sidestepping.

RESULTS

For kinematic variables, unplanned sidestepping produced a wide range of small to large increases in knee extension angles, small and moderate increases in knee abduction angles and a small increase in internal rotation angle relative to planned sidestepping during the sidestepping manoeuvre. For kinetic variables, unplanned sidestepping produced mostly small (small to large) increases in knee flexor moments, small to moderate increases in knee abductor moments and mostly moderate (small to large) increases in internal rotator moments relative to planned sidestepping.

LIMITATIONS

Approach velocity constraints during the sidestepping manoeuvre were lifted due to the low number of eligible studies. The varying approach velocities included (ranging from 3.0 to 5.5 m s(−1)) may impact the kinematic and kinetic variables examined in this review.

CONCLUSIONS

Differences in knee mechanics between planned and unplanned sidestepping exist. The most substantial effects occurred during the weight acceptance phase of sidestepping. It seems that biomechanical factors commonly associated with anterior cruciate ligament injury risk are affected the most during the loading phase compared with peak push-off; made evident in the coronal (abductor) and transverse (internal rotator) knee kinetic data presented in this review. The authors of this review propose a rationale for the incorporation of unplanned sport tasks in the development of anterior cruciate ligament injury screening and in prophylactic training programmes.

Lower extremity muscle activation and alignment during the soccer instep and side-foot kicks

STUDY DESIGN

Controlled laboratory study.

OBJECTIVES

To quantify phase duration and lower extremity muscle activation and alignment during the most common types of soccer kick-the instep kick and side-foot kick. A second purpose was to test the hypotheses that different patterns of lower extremity muscle activation occur between the 2 types of kicks and between the kicking limb compared to the support limb.

BACKGROUND

Soccer players are at risk for lower extremity injury, especially at the knee. Kicking the soccer ball is an essential, common, and distinctive part of a soccer player's activity that plays a role in soccer player injury. Regaining the ability to kick is also essential for soccer athletes to return to play after injury.

METHODS

Thirteen male soccer players underwent video motion analysis and electromyography (EMG) of 7 muscles in both the kicking and supporting lower extremity (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings, gastrocnemius) and 2 additional muscles in the kicking limb only (hip adductors, tibialis anterior). Five instep and 5 side-foot kicks were recorded for each player. Analysis-of-variance models were used to compare EMG activity between type of kicks and between the kicking and nonkicking lower extremity.

RESULTS

Five phases of kicking were identified: (1) preparation, (2) backswing, (3) limb cocking, (4) acceleration, and (5) follow-through. Comparing the kicking limb between the 2 types of kick, significant interaction effects were identified for the hamstrings (P = .02) and the tibialis anterior (P<.01). Greater activation of the kicking limb iliacus (P<.01), gastrocnemius (P<.01), vastus medialis (P = .016), and hip adductors (P<.01) occurred during the instep kick. Significant differences were seen between the kicking limb and the support limb for all muscles during both types of kick.

CONCLUSIONS

Certain lower extremity muscle groups face different demands during the soccer instep kick compared to the soccer side-foot kick. Similarly, the support limb muscles face different demands than the kicking limb during both kicks. Better definition of lower extremity function during kicking provides a basis for improved insight into soccer player performance, injury prevention, and rehabilitation.

Linear and angular head accelerations during heading of a soccer ball

PURPOSE

Cognitive deficits observed in professional soccer players may be related to heading of a soccer ball. To assess the severity of a single instance of heading a soccer ball, this study experimentally and theoretically evaluated the linear and angular accelerations experienced by the human head during a frontal heading maneuver.

METHODS

Accelerations were measured using a set of three triaxial accelerometers mounted to the head of each of four adult male subjects. These measurements (nine signals) were used to estimate the linear acceleration of the mass center and the angular acceleration of the head. Results were obtained for ball speeds of 9 and 12 m.s(-1) (approximately 20 and 26 mph). A simple mathematical model was derived for comparison.

RESULTS

At 9 m.s(-1), peak linear acceleration of the head was 158 +/- 19 m.s(-2) (mean +/- standard deviation) and peak angular acceleration was 1302 +/- 324 rad.s(-2); at 12 m.s(-1), the values were 199 +/- 27 m.s-2 and 1457 +/- 297 rad.s-2, respectively. The initial acceleration pulses lasted approximately 25 ms. Measured head accelerations confirmed laboratory headform measurements reported in the literature and fell within the ranges predicted by the theoretical model.

CONCLUSIONS

Linear and angular acceleration levels for a single heading maneuver were well below those thought to be associated with traumatic brain injury, as were computed values of the Gadd Severity Index and the Head Injury Criterion. However, the effect of repeated acceleration at this relatively low level is unknown.

Office laboratory procedures, office economics, parenting and parent education, and urinary tract infection

We again review four areas of interest to office-based pediatricians: office laboratory procedures, office economics, parenting and patient education, and urinary tract infections. Sean Elliott provides an update on the Clinical Laboratories Improvement Amendments (CLIA) and their impact of office practice. Eve Shapiro reviews office economics, focusing on measuring quality of care, use of performance data, costs of new technologies, and the impact of managed care on the medical marketplace. John Walter offers an update on parenting and parent education, with approaches to counseling families about overuse of antibiotics, teen pregnancy, hyperactivity, violence, and asthma. Richard Wahl reviews the recent research on urinary tract infection, with special attention paid to office diagnosis and management, longitudinal studies of children with urinary tract infections, and the controversy surrounding the American Academy of Pediatrics Task Force on Circumcision report.