The mechanistic connection between the trunk, hip, knee, and anterior cruciate ligament injury

ABCs of Evidence-based Anterior Cruciate Ligament Injury Prevention Strategies in Female Athletes

Anterior cruciate ligament (ACL) injury is a major concern in physically active females. Although ACL reconstruction techniques have seen significant advances in recent years, risk associated with re-injury and future osteoarthritis remains a major concern. Thus, prevention of ACL injury is a logical step to protect and preserve healthy knee joints in young athletes. The current report aims to summarize a list of evidence-based prevention strategies to reduce ACL injury in female athletes. A list of six critical principles, which come from documented, large scale clinical trial studies and further analyses, were presented with ABC format including age, biomechanics, compliance, dosage, exercise, and feedback. Also, a grade for evidence and implications of future research is noted. Finally, in the conclusion section, importance of collaborative efforts from healthcare practitioners, researchers, and personnel associated with athletics is addressed.

High knee abduction moments are common risk factors for patellofemoral pain (PFP) and anterior cruciate ligament (ACL) injury in girls: is PFP itself a predictor for subsequent ACL injury?

BACKGROUND

Identifying risk factors for knee pain and anterior cruciate ligament (ACL) injury can be an important step in the injury prevention cycle.

OBJECTIVE

We evaluated two unique prospective cohorts with similar populations and methodologies to compare the incidence rates and risk factors associated with patellofemoral pain (PFP) and ACL injury.

METHODS

The 'PFP cohort' consisted of 240 middle and high school female athletes. They were evaluated by a physician and underwent anthropometric assessment, strength testing and three-dimensional landing biomechanical analyses prior to their basketball season. 145 of these athletes met inclusion for surveillance of incident (new) PFP by certified athletic trainers during their competitive season. The 'ACL cohort' included 205 high school female volleyball, soccer and basketball athletes who underwent the same anthropometric, strength and biomechanical assessment prior to their competitive season and were subsequently followed up for incidence of ACL injury. A one-way analysis of variance was used to evaluate potential group (incident PFP vs ACL injured) differences in anthropometrics, strength and landing biomechanics. Knee abduction moment (KAM) cut-scores that provided the maximal sensitivity and specificity for prediction of PFP or ACL injury risk were also compared between the cohorts.

RESULTS

KAM during landing above 15.4 Nm was associated with a 6.8% risk to develop PFP compared to a 2.9% risk if below the PFP risk threshold in our sample. Likewise, a KAM above 25.3 Nm was associated with a 6.8% risk for subsequent ACL injury compared to a 0.4% risk if below the established ACL risk threshold. The ACL-injured athletes initiated landing with a greater knee abduction angle and a reduced hamstrings-to-quadriceps strength ratio relative to the incident PFP group. Also, when comparing across cohorts, the athletes who suffered ACL injury also had lower hamstring/quadriceps ratio than the players in the PFP sample (p<0.05).

CONCLUSIONS

In adolescent girls aged 13.3 years, >15 Nm of knee abduction load during landing is associated with greater likelihood of developing PFP. Also, in girls aged 16.1 years who land with >25 Nm of knee abduction load during landing are at increased risk for both PFP and ACL injury.

Squatting mechanics in people with and without anterior cruciate ligament reconstruction: the influence of graft type

BACKGROUND

Single-legged squat mechanics change after anterior cruciate ligament (ACL) reconstruction and rehabilitation, but it is unclear if changes in squat mechanics are graft specific.

PURPOSE

To investigate graft differences in biomechanics of the knee, hip, and trunk during the single-legged squat in patients with ACL-reconstructed knees, determine if these factors were associated with deficits in knee extension moment, and determine if subjective knee function and squat biomechanics are related.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 106 individuals were grouped based on surgical status and graft type (51 control, 34 bone-patellar tendon-bone [BPTB], 21 ipsilateral semitendinosus and gracilis autograft [ISGA]). Motion capture interfaced with force plates was used to capture single-legged squat performance in the ACL reconstructed and dominant control limbs. Variables were captured at peak knee flexion.

RESULTS

Controls exhibited greater knee extension moment (P = .04), knee flexion (P = .002), and hip adduction angles (P = .04) compared with the reconstructed groups. The ISGA group demonstrated greater forward (P = .01) and lateral (P = .002) trunk flexion over the reconstructed limb. Summated extension moment did not differ between groups (P = .42). Knee extension moment was correlated with lateral trunk flexion (r = -0.31, P = .03) in the control group and knee flexion angle (r = -0.44, P = .04) in the ISGA group. Subjective knee function scores were correlated with lateral trunk flexion (r = -0.45, P = .008) in the BPTB group and with hip adduction angle (r = -0.46, P = .04) and hip extension moment (r = 0.48, P = .03) in the ISGA group.

CONCLUSION

Knee and hip biomechanics were related to surgical status but not graft type. Increased forward and lateral trunk motion in the ISGA group may be a mechanism to protect the knee by minimizing motion during squatting or related to surgical selection bias. Secondary findings (summated extensor moments and correlations) most likely represent a strategy to shift the squat demands from the knee to the hip.

CLINICAL RELEVANCE

Clinicians should target these neuromuscular deficits during rehabilitation and training programs after ACL reconstruction.

Lower extremity fatigue, sex, and landing performance in a population with recurrent low back pain

CONTEXT

Low back pain and lower extremity injuries affect athletes of all ages. Previous authors have linked a history of low back pain with lower extremity injuries. Fatigue is a risk factor for lower extremity injuries, some of which are known to affect female athletes more often than their male counterparts.

OBJECTIVE

To determine the effects of lower extremity fatigue and sex on knee mechanics, neuromuscular control, and ground reaction force during landing in people with recurrent low back pain (LBP).

DESIGN

Cross-sectional study.

SETTING

A clinical biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty-three young adults with recurrent LBP but without current symptoms.

INTERVENTION(S)

Fatigue was induced using a submaximal free-weight squat protocol with 15% body weight until task failure was achieved.

MAIN OUTCOME MEASURE(S)

Three-dimensional knee motion, knee and ankle moments, ground reaction force, and trunk and lower extremity muscle-activity measurements were collected during 0.30-m drop vertical-jump landings.

RESULTS

Fatigue altered landing mechanics, with differences in landing performance between sexes. Women tended to have greater knee-flexion angle at initial contact, greater maximum knee internal-rotation angle, greater maximum knee-flexion moment, smaller knee-adduction moment, smaller ankle-inversion moment, smaller ground reaction force impact, and earlier multifidus activation. In men and women, fatigue produced a smaller knee-abduction angle at initial contact, greater maximum knee-flexion moment, and delays in semitendinosus, multifidus, gluteus maximus, and rectus femoris activation.

CONCLUSIONS

Our results provide evidence that during a fatigued 0.30-m landing sequence, women who suffered from recurrent LBP landed differently than did men with recurrent LBP, which may increase women's exposure to biomechanical factors that can contribute to lower extremity injury.

Medical expenditures in division I collegiate athletics: an analysis by sport and gender

OBJECTIVE

Medical expenses for collegiate athletics include providing a training room with its supplies, equipment, personnel costs, and insurance coverage. Additional expenses beyond the training room include imaging, diagnostic testing, specialty consultations, and surgeries. We hypothesized that there would be no difference in average expenses or number of claims between male and female athletes over a 5-year period.

DESIGN

Prospective patient cohort.

SETTING

A sports medicine center serving athletes in Big 10 Conference intercollegiate sports.

ASSESSMENT OF RISK FACTORS

All medical claims and charges for 36 varsity teams were analyzed from 2005 to 2010. The teams were categorized into 3 groups: female-only teams, male-only teams, and coed teams. Analysis of sports with corresponding male and female teams was also performed.

MAIN OUTCOME MEASUREMENTS

Claims and charges for medical care for 36 intercollegiate athletic teams over 5 years.

RESULTS

Individual team claims and charges were stable over the study period. In 11 of the 14 sex-matched sports, the female teams had higher average annual charges. After normalizing for roster size in the sex-matched sports, females had 0.97 more average annual claims (P < 0.01) and $1459 higher annual charges (P = 0.001) than their male counterparts. The charges per claim were similar between the sexes. The 5 teams with the highest average annual charges were football, wrestling, softball, women's crew, and men's lacrosse. When normalized for roster size, the 5 sports with the highest average annual charges per athlete were softball, women's diving, men's basketball, wrestling, and men's gymnastics.

CONCLUSION

Charges per claim were similar between the sex-matched sports, but the female sports had a higher number of annual claims per athlete and thus higher total charges per athlete/year. Football had the highest average annual total charges as a team, but when normalized for roster size football charges per athlete/year were similar to those of other sports.

Anterior cruciate ligament injury: mechanisms of injury and strategies for injury prevention

Anterior cruciate ligament (ACL) injury is a common sports injury which can have severe negative consequences. Neuromuscular factors that increase risk, such as knee landing kinematics, may be ameliorated through training. Effective ACL injury prevention programs exist, although the ideal program is yet to be determined. It is recommended that athletes engaged in high-risk sports participate in an ACL injury prevention program to reduce the risk of sustaining this injury.

Lower-limb kinematics of single-leg squat performance in young adults

PURPOSE

To determine the kinematic parameters that characterize good and poor single-leg squat (SLS) performance.

METHODS

A total of 22 healthy young adults free from musculoskeletal impairment were recruited for testing. For each SLS, both two-dimensional video and three-dimensional motion analysis data were collected. Pelvis, hip, and knee angles were calculated using a reliable and validated lower-limb (LL) biomechanical model. Two-dimensional video clips of SLSs were blindly assessed in random order by eight musculoskeletal physiotherapists using a 10-point ordinal scale. To facilitate between-group comparisons, SLS performances were stratified by tertiles corresponding to poor, intermediate, and good SLS performance.

RESULTS

Mean ratings of SLS performance assessed by physiotherapists were 8.3 (SD 0.5), 6.8 (SD 0.7), and 4.0 (SD 0.8) for good, intermediate, and poor squats, respectively. Three-dimensional analysis revealed that people whose SLS performance was assessed as poor exhibited increased hip adduction, reduced knee flexion, and increased medio-lateral displacement of the knee joint centre compared to those whose SLS performance was assessed as good (p≤0.05).

CONCLUSIONS

Overall, poor SLS performance is characterized by inadequate knee flexion and excessive frontal plane motion of the knee and hip. Future investigations of SLS performance should consider standardizing knee flexion angle to illuminate other influential kinematic parameters.

The validity of 2-dimensional measurement of trunk angle during dynamic tasks

PURPOSE/BACKGROUND

Injury screening methods that use three-dimensional (3D) motion analysis accurately predict the risk of injuries, yet are expensive. There is great need for valid, cost-effective techniques that can be used in large-scale assessments. Utilizing two-dimensional (2D) measures of lateral trunk motion may identify athletes at risk for lower extremity injury. The purpose of this research was to determine the strength of the relationships between 2D and 3D calculations of lateral trunk angle for female athletes performing a single-leg cross drop landing.

METHODS

Twenty-one high-school female volleyball players performed a single-leg cross drop landing onto a force plate. The 3D angular trunk motion was calculated, and four different 2D measures of lateral trunk angle were calculated for both left and right landing leg. A one-way multivariate analysis of variance was used to compare 2D measures to the 3D measurements, and Pearson correlations were used to determine the strength of these relationships.

RESULTS

The angle formed by the medial shoulder joint center, medial ASIS, and vertical line (LTA4) was similar to the 3D measures of lateral trunk angle during landing (r-values ≥ 0.62; p-values ≤ 0.003; mean differences, -1.0° to 1.2°).

CONCLUSIONS

Given the recent focus on the role of the trunk in lower extremity injury, using the 2D LTA4 assessment may expand existing assessments into a composite model that can more accurately assess female athletes at risk for injury than models that do not include trunk analysis.

CLINICAL RELEVANCE

Existing models that enable clinicians to effectively identify female athletes at risk for lower extremity injury may be enhanced by including accurate assessments of lateral trunk motion.

Diagnosis and management of acute medial tibial stress syndrome in a 15 year old female surf life-saving competitor

BACKGROUND AND PURPOSE

As the profound health and cost benefits of physical activity to society are established and participation guidelines implemented, health practitioners are increasingly expected to utilize efficacious and justified injury management and prevention strategies. The complex and multifactorial nature of sports injury makes elucidation of multiple risk factors and how they may subtly and variably interact, difficult. The purpose of this case report is to discuss the differential diagnosis, acute management and rehabilitation of a case of medial tibial stress syndrome (MTSS) in a surf life-saving athlete, in the context of sports injury prevention.

CASE DESCRIPTION

The subject of this case study, a 15 year old female surf life-saving competitor, presented to the physiotherapist (PT) with recent onset, first episode, bilateral, diffuse posteromedial shin pain. Differential diagnosis, acute management, rehabilitation and preventative strategies for the subject are presented.

DISCUSSION

Emerging injury surveillance research in surf life-saving suggests minor and major trauma as primary causative factors, however, the significance of high training volumes is likely underestimated. The influence of biomechanical, and subtle arthrokinematic dysfunctions on established risk factors for MTSS injury and prevention of re-injury for this subject, are also discussed. Furthermore, the concept of preventing tibial stress fracture (TSF) by successfully managing acute MTSS, is presented. Lastly, a critical analysis of reliability of clinical assessment methodologies utilised with the subject is provided.

LEVEL OF EVIDENCE

Level 5; Single case report.

FMS™ scores and low-back loading during lifting--whole-body movement screening as an ergonomic tool?

BACKGROUND

Previous research suggests that a general whole-body movement screen could be used to identify personal movement attributes that promote potentially injurious low-back loading patterns at work. The purpose of this study was to examine the relationship between Functional Movement Screen™ (FMS) composite scores and the low-back loading response to lifting.

METHODS

Fifteen men who scored greater than 14 on the FMS (high-scorers) and 15 height- and weight-matched low-scorers (FMS < 14) performed sagittally symmetric and asymmetric laboratory-based lifting tasks. A three-dimensional dynamic biomechanical model was used to calculate peak low-back loading levels, and the angle of the lumbar spine was captured at the instant when the peak compressive force was applied.

RESULTS

Regardless of the lifting task performed, there were no differences in peak low-back compression (p ≥ 0.4157), anterior/posterior reaction shear (p ≥ 0.5645), or medial/lateral reaction shear (p ≥ 0.2581) forces between the high- and low-scorers. At the instant when peak compressive forces were applied, differences in the lumbar spine angle between high- and low-scores were not statistically significant about the lateral bend (p ≥ 0.4215), axial twist (p ≥ 0.2734), or flexion/extension (p ≥ 0.1354) axes, but there was a tendency for the lumbar spine to be more deviated in the low-scorers.

CONCLUSIONS

Using the previously established injury prediction threshold value of 14, the composite FMS score was not related to the peak low-back loading magnitudes in lifting. Though not statistically significant, the tendency for the lumbar spines of low-scorers to be more deviated when the peak low-back compression force was imposed could be biomechanically meaningful because spinal load tolerance varies with posture. Future attempts to modify or reinterpret FMS scoring are warranted given that several previous studies have revealed links between composite FMS scores and musculoskeletal complaints.

A predictive model to estimate knee-abduction moment: implications for development of a clinically applicable patellofemoral pain screening tool in female athletes

CONTEXT

Prospective measures of high external knee-abduction moment (KAM) during landing identify female athletes at increased risk of patellofemoral pain (PFP). A clinically applicable screening protocol is needed.

OBJECTIVE

To identify biomechanical laboratory measures that would accurately quantify KAM loads during landing that predict increased risk of PFP in female athletes and clinical correlates to laboratory-based measures of increased KAM status for use in a clinical PFP injury-risk prediction algorithm. We hypothesized that we could identify clinical correlates that combine to accurately determine increased KAM associated with an increased risk of developing PFP.

DESIGN

Descriptive laboratory study.

SETTING

Biomechanical laboratory.

PATIENTS OR OTHER PARTICIPANTS

Adolescent female basketball and soccer players (n = 698) from a single-county public school district.

MAIN OUTCOME MEASURE(S)

We conducted tests of anthropometrics, maturation, laxity, flexibility, strength, and landing biomechanics before each competitive season. Pearson correlation and linear and logistic regression modeling were used to examine high KAM (>15.4 Nm) compared with normal KAM as a surrogate for PFP injury risk.

RESULTS

The multivariable logistic regression model that used the variables peak knee-abduction angle, center-of-mass height, and hip rotational moment excursion predicted KAM associated with PFP risk (>15.4 NM of KAM) with 92% sensitivity and 74% specificity and a C statistic of 0.93. The multivariate linear regression model that included the same predictors accounted for 70% of the variance in KAM. We identified clinical correlates to laboratory measures that combined to predict high KAM with 92% sensitivity and 47% specificity. The clinical prediction algorithm, including knee-valgus motion (odds ratio [OR] = 1.46, 95% confidence interval [CI] = 1.31, 1.63), center-of-mass height (OR = 1.21, 95% CI = 1.15, 1.26), and hamstrings strength/body fat percentage (OR = 1.80, 95% CI = 1.02, 3.16) predicted high KAM with a C statistic of 0.80.

CONCLUSIONS

Clinical correlates to laboratory-measured biomechanics associated with an increased risk of PFP yielded a highly sensitive model to predict increased KAM status. This screening algorithm consisting of a standard camcorder, physician scale for mass, and handheld dynamometer may be used to identify athletes at increased risk of PFP.

Changes in leg kinematics in response to unpredictability in lateral jump execution

Lateral movements like cutting are essential in many team sport disciplines. The aim of the present study was to analyse adaptations in motor control in response to task unpredictability during lateral movement execution. Twelve subjects performed lateral jumps with different landing modalities (stable, sliding or counteracting) that were either known (predictable setting) or unknown (unpredictable setting) prior to movement execution. Results revealed that regardless of the landing modality, hip joint abduction was significantly greater in the unpredictable compared to predictable setting. Furthermore, during the sliding landing modality, hip flexion decreased from 211 ± 7° to 207 ± 7° and knee flexion decreased from 26 ± 4° to 24 ± 4° at the instant of ground contact in the unpredictable compared to predictable condition. During the stable landing modality, the knee joint abduction increased from -0.3 ± 6° to -3 ± 6° after initial ground contact in the unpredictable compared to predictable setting. The present results support our hypothesis that pre-programmed motor activity depends on the predictability of the landing modality during lateral movements. According to its adaptation in the frontal plane and in some extent in the sagittal plane, the hip joint seems to play the major role in the modulation of the pre-programmed activity for successful lateral jump execution in an unpredictable setting. However, these kinematic adaptations are concerning since these changes were associated with higher knee abduction during the stable landing modality and therefore with possible higher risk of injury.

Improvements in hip muscle performance result in increased use of the hip extensors and abductors during a landing task

BACKGROUND

Impaired hip muscle performance has been implicated as a contributing factor to the increased risk of anterior cruciate ligament (ACL) injury in women.

PURPOSE

To determine the influence of a hip-focused training program on lower extremity biomechanics during a drop-jump task.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twenty-one recreationally active women (18-25 years of age) participated in a 4-week training program consisting of hip-focused plyometric and balance perturbation exercises (3 times/wk, 30 min/session). Maximum isometric strength of the hip extensors, hip abductors, and knee extensors was assessed, along with lower extremity biomechanics during a drop-jump task. All assessments were performed within 5 days of initiation and completion of the training program.

RESULTS

After training, subjects demonstrated significantly greater maximum isometric strength of the hip extensors (2.87 ± 0.7 vs 3.11 ± 0.7 N·m/kg; P < .01) and hip abductors (2.08 ± 0.7 vs 2.23 ± 0.07 N·m/kg; P = .004). No significant difference in knee extensor strength was observed. After training, subjects landed with significantly greater peak knee flexion (94.0° ± 8.5° vs 98.0° ± 10.1°; P < .001) and hip flexion (83.4° ± 7.6° vs 89.9° ± 8.8°; P = .008) and a lower knee/hip extensor moment ratio (1.33 ± 0.6 vs 0.99 ± 0.3; P = .001). In addition, subjects demonstrated significantly lower peak knee abduction angles (6.8° ± 3.3° vs 5.6° ± 3.1°; P = .04) and average knee adductor moments (0.06 ± 0.1 vs -0.02 ± 0.1 N·m/kg; P < .001).

CONCLUSION

Changes in lower extremity biomechanics consistent with decreased risk for ACL injury were observed after participation in a hip-focused training program.

CLINICAL RELEVANCE

The study results suggest that ACL injury prevention programs targeting hip muscle performance may be important in mitigating biomechanical risk factors associated with ACL injury in women.

The association of aerobic fitness with injuries in the fire service

The aim of the present study was to understand the risk of injury in relation to fitness in a retrospective occupational cohort of firefighters in Tucson, Arizona, from 2005 to 2009. Annual medical evaluations and injury surveillance data were linked to compare levels of aerobic fitness in injured employees with those in noninjured employees. The individual outcomes evaluated included all injuries, exercise-related injuries, and sprains and strains. Time-to-event analyses were conducted to determine the association between levels of fitness and injury likelihood. Fitness, defined by relative aerobic capacity (Vo2max), was associated with injury risk. Persons in the lowest fitness level category (Vo2max <43 mL/kg/minute) were 2.2 times more likely (95% confidence interval: 1.72, 2.88) to sustain injury than were those in the highest fitness level category (Vo2max >48 mL/kg/minute). Those with a Vo2max between 43 and 48 mL/kg/minute were 1.38 times (95% confidence interval: 1.06, 1.78) more likely to incur injury. Hazard ratios were found to be greater for sprains and strains. Our results suggest that improving relative aerobic capacity by 1 metabolic equivalent of task (approximately 3.5 mL/kg/minute) reduces the risk of any injury by 14%. These findings illustrate the importance of fitness in reducing the risk of injury in physically demanding occupations, such as the fire service, and support the need to provide dedicated resources for structured fitness programming and the promotion of injury prevention strategies to people in those fields.

Prevention of anterior cruciate ligament injuries in sports. Part I: systematic review of risk factors in male athletes

PURPOSE

The purpose of this study was to report a comprehensive literature review on the risk factors for anterior cruciate ligament (ACL) injuries in male athletes.

METHODS

All abstracts were read and articles of potential interest were reviewed in detail to determine on inclusion status for systematic review. Information regarding risk factors for ACL injuries in male athletes was extracted from all included studies in systematic fashion and classified as environmental, anatomical, hormonal, neuromuscular, or biomechanical. Data extraction involved general characteristics of the included studies (type of study, characteristics of the sample, type of sport), methodological aspects (for quality assessment), and the principal results for each type of risk factor.

RESULTS

The principal findings of this systematic review related to the risk factors for ACL injury in male athletes are: (1) most of the evidence is related to environmental and anatomical risk factors; (2) dry weather conditions may increase the risk of non-contact ACL injuries in male athletes; (3) artificial turf may increase the risk of non-contact ACL injuries in male athletes; (4) higher posterior tibial slope of the lateral tibial plateau may increase the risk of non-contact ACL injuries in male athletes.

CONCLUSION

Anterior cruciate ligament injury in male athletes likely has a multi-factorial aetiology. There is a lack of evidence regarding neuromuscular and biomechanical risk factors for ACL injury in male athletes. Future research in male populations is warranted to provide adequate prevention strategies aimed to decrease the risk of this serious injury in these populations.

Return to sport after patellar dislocation or following surgery for patellofemoral instability

Patellofemoral instability may occur in a young population as a result of injury during sporting activities. This review focuses on return to sport after one episode of dislocation treated no operatively and as well after surgery for chronic patellofemoral instability. With or without surgery, only two-thirds of patients return to sports at the same level as prior to injury. A high-quality rehabilitation programme using specific exercises is the key for a safe return to sporting activities. To achieve this goal, recovery of muscle strength and dynamic stability of the lower limbs is crucial. The focus should be directed to strengthen the quadriceps muscle and pelvic stabilizers, as well as lateral trunk muscle training. Patient education and regularly performed home exercises are other key factors that can lead to a successful return to sports. The criteria for a safe return to sports include the absence of pain, no effusion, a complete range of motion, almost symmetrical strength, and excellent dynamic stability. Level of evidence IV.

Test-retest reliability of three-dimensional kinematics using an electromagnetic tracking system during single-leg squat and stepping maneuver

The electromagnetic tracking system (ETS) has been used to analyze three-dimensional (3D) lower limb kinematics. The single-leg squat and stepping maneuver are useful tasks to evaluate lower extremity alignment in a clinical setting. The purpose of this study was to evaluate the test-retest reliability of trunk, pelvis, hip, and knee 3D kinematics using an ETS during single-leg squat and stepping maneuver and compare 3D kinematics between tasks. Twenty healthy volunteers (10 males and 10 females) completed two test sessions 3-5 days apart. Three-dimensional kinematics using an ETS was assessed during single-leg squat and stepping maneuver. Overall, intrarater-intrasession reliability (ICCs=0.83-1.00) and intersession reliabilities (ICCs=0.82-0.97) were high during single-leg squat and stepping maneuver. The intrasession minimal detectable change (MDC) ranged from 1.3° for the knee frontal plane range of motion for single-leg squat to 6.2° for the pelvic transverse range of motion for the stepping maneuver. Intersession MDC values ranged from 1.2° for the ipsilateral trunk lean for the single-leg squat to 8.3° for hip flexion for the stepping maneuver. Healthy participants exhibited greater anterior pelvic tilt, more hip flexion, and less contralateral pelvis forward excursion (p<0.05) during single-leg squat compared with the stepping maneuver. These findings suggest that the 3D kinematics of the trunk, pelvis, hip, and knee using an ETS is reliable during single-leg squat and the stepping maneuver. Minimal detectable change values were low during the evaluated activities. Intertask comparisons revealed differences in hip and pelvis kinematics.

Diagnosis and management of atypical and persistent anterolateral knee pain in a 16-year-old triathlete: an iterative process

INTRODUCTION AND BACKGROUND

The subject of this case study, a 16-year-old female triathlete, presented to physiotherapy reporting a 6 month history of anterior knee pain, with symptoms unchanged upon resuming a graduated triathlon training program, despite 3 months rest from all training.

CASE DESCRIPTION

The case describes the differential diagnosis and management of patellofemoral pain syndrome (PFPS), iliotibial band syndrome (ITBS), and discoid lateral meniscus (DLM) in an adolescent female triathlete. Clinical reasoning and rehabilitation strategies are presented with respect to literature base. Final outcome was full resolution of symptoms and return to full athletic function, however, symptoms were relatively persistent and atypical.

PURPOSE

This case report discusses the differential diagnosis and management of persistent and atypical anterior knee pain in a sixteen-year-old female triathlete. In such cases, the diagnostic process is often iterative, where intervention serves both therapeutic and diagnostic purposes.

DISCUSSION

Recent changes in the understanding of the pathophysiology of ITBS and links between the anterior and lateral knee compartments through highly innervated knee synovial tissue assist the therapist's understanding of how these conditions may occur concomitantly, with resulting atypical symptoms. The potential influences of likely changes in the subject's peripheral and central nervous system on symptom perception is also discussed.

LEVEL OF EVIDENCE

Level 5; Single case report.

Basic principles regarding strength, flexibility, and stability exercises

Strength, flexibility, and stability are physiologic parameters associated with health-related physical fitness. Each of these domains affects health in general, the risk of injury, how an injury is treated, and performance in activities of daily living and sports. These domains are affected by individual phenotype, age, deconditioning, occupational activity, and formal exercise. Deficits or loss of strength, flexibility, and stability can be prevented or reduced with exercise programs. Normal muscle strength has been associated with general health benefits, increased life expectancy, psychological benefits, prevention of illness, and reduction of disability in older adults. Static flexibility programs have been shown to improve joint range of motion and tolerance to stretch but do not appear to reduce the risk of musculoskeletal injury and may impair muscle performance immediately after a static stretch. Dynamic flexibility, on the other hand, may enhance power and improve sports-specific performance. Stability training leads to improved balance and neuromuscular control, may prevent injury to the knee and ankle joints, and can be used for treatment of patients with low back pain.

Preventive exercise in sports

Sports injuries are common and can result in significant problems, such as pain, social isolation, depression, disability (temporary or permanent), loss of income, or loss of scholarship. Further, sports injuries can predispose the athlete to future injury or degenerative disorders, for example, osteoarthritis. Therefore, a preventive approach is paramount, and exercise can be used as an effective tool to prevent sports-related injuries. This article describes the process by which successful injury prevention programs can be developed and implemented by using noncontact anterior cruciate ligament injury programs as an example. The knowledge gained from this information can be used in the future to assist in the creation of new injury prevention programs for other common sports injuries.

Progressive resistance, whole body long-axis rotational training improves kicking motion motor performance

OBJECTIVES

To evaluate lower extremity muscle activation, peak resultant ground reaction force (GRF) production and quickness during performance of a kicking motion following progressive resistance, whole body long-axis rotational training.

DESIGN

Randomized, controlled study.

SETTING

Kinesiological research laboratory.

PARTICIPANTS

Thirty-six healthy subjects were assigned to a training (Group 1) or to a control (Group 2) group.

MAIN OUTCOME MEASURES

Time-synchronized EMG (1000 Hz), peak resultant GRF (1000 Hz) and two-dimensional kinematic (60 Hz) data were collected as subjects responded to an audio cue by kicking a cone. Group mean change differences (MCD) were compared using independent sample t-tests. Fisher's exact tests were used to determine group differences in the proportion of subjects that displayed earlier activation responses post-training.

RESULTS

Group 1 MCD revealed earlier gluteus maximus, gluteus medius, rectus femoris, medial hamstrings, and biceps femoris activation timing than Group 2 (P ≤ 0.006) and more Group 1 subjects displayed earlier activation of these muscles post-training (P ≤ 0.041). Group 1 MCD also revealed earlier peak resultant GRF timing and improved "kick quickness" than Group 2 (P ≤ 0.014) and more Group 1 subjects displayed earlier response timing for these variables post-training (P = 0.035).

CONCLUSION

Progressive resistance, whole body long-axis rotational training may improve performance during sports movements that require quick, integrated trunk-lower extremity function.

The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis

BACKGROUND

In female athletes, sports-related injuries to the anterior cruciate ligament (ACL) increase during adolescence and peak in incidence during the mid- to late teens. Although biomechanical investigations indicate that a potential window of opportunity exists for optimal timing for the initiation of integrative neuromuscular training (NMT) in young female athletes, the influence of the timing of initiation of these programs on the efficacy of ACL injury reduction has yet to be evaluated. HYPOTHESIS/ PURPOSE: The purpose of the current report was to systematically review and synthesize the scientific literature regarding the influence of age of NMT implementation on the effectiveness for reduction of ACL injury incidence. The hypothesis tested was that NMT would show a greater effect in younger populations.

STUDY DESIGN

Meta-analysis; Level of evidence 1a.

METHODS

Data were pooled from 14 clinical trials that met the inclusion criteria of (1) number of ACL injuries reported; (2) NMT program used; (3) female participants were included; (4) investigations used prospective, controlled trials; and (5) age of participants was documented or was obtainable upon contact with the authors. A meta-analysis with odds ratio (OR) was used to compare the ratios of ACL injuries between intervention and control groups among differing age categorizations.

RESULTS

A meta-analysis of the 14 included studies demonstrated significantly greater knee injury reduction in female athletes who were categorized in the preventive NMT group compared with those who were in the control group (OR: 0.54; 95% confidence interval [CI]: 0.35, 0.83). Lower ACL injuries in mid-teens (OR 0.28; CI: 0.18, 0.42) compared with late teens (OR 0.48; CI: 0.21, 1.07) and early adults (OR 1.01; CI: 0.62, 1.64) were found in participants undergoing NMT.

CONCLUSION

The findings of this meta-analysis revealed an age-related association between NMT implementation and reduction of ACL incidence. Both biomechanical and the current epidemiological data indicate that the potential window of opportunity for optimized ACL injury risk reduction may be before the onset of neuromuscular deficits and peak knee injury incidence in female athletes. Specifically, it may be optimal to initiate integrative NMT programs during early adolescence, before the period of altered mechanics that increase injury risk.

Failure of anterior cruciate ligament reconstruction

Failure after anterior cruciate ligament reconstruction is a potentially devastating event that affects a predominantly young and active population. This review article provides a comprehensive analysis of the potential causes of failure, including graft failure, loss of motion, extensor mechanism dysfunction, osteoarthritis, and infection. The etiology of graft failure is discussed in detail with a particular emphasis on failure after anatomic anterior cruciate ligament reconstruction.