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?

Measurement Properties of Clinically Accessible Movement Assessment Tools for Analyzing Single-Leg Squats and Step-Downs: A Systematic Review

CONTEXT

Poor lower-extremity biomechanics are predictive of increased risk of injury. Clinicians analyze the single-leg squat (SLS) and step-down (SD) with rubrics and 2D assessments to identify these poor lower-extremity biomechanics. However, evidence on measurement properties of movement assessment tools is not strongly outlined. Measurement properties must be established before movement assessment tools are recommended for clinical use.

OBJECTIVE

The purpose of this study was to systematically review the evidence on measurement properties of rubrics and 2D assessments used to analyze an SLS and SD.

EVIDENCE ACQUISITION

The search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The search was performed in PubMed, SPORTDiscus, and Web of Science databases. The COnsensus-based Standards for the selection of health Measurement INstruments multiphase procedure was used to extract relevant data, evaluate methodological quality of each study, score the results of each movement assessment, and synthesize the evidence.

EVIDENCE SYNTHESIS

A total of 44 studies were included after applying eligibility criteria. Reliability and construct validity of knee frontal plane projection angle was acceptable, but criterion validity was unacceptable. Reliability of the Chmielewski rubric was unacceptable. Content validity of the knee-medial-foot and pelvic drop rubrics was acceptable. The remaining rubrics and 2D measurements had inconclusive or conflicting results regarding reliability and validity.

CONCLUSIONS

Knee frontal plane projection angle is reliable for analyzing the SLS and SD; however, it does not serve as a substitute for 3D motion analysis. The Chmielewski rubric is not recommended for assessing the SLS or SD as it may be unreliable. Most movement assessment tools yield indeterminate results. Within the literature, standardized names, procedures, and reporting of movement assessment tool reliability and validity are inconsistent.

Measurement Properties of Clinically Accessible Movement Assessment Tools for Analyzing Jump Landings: A Systematic Review

CONTEXT

Lower-extremity musculoskeletal injury is commonly associated with poor movement patterns at the trunk, hip, and knee. Efforts have been focused on identifying poor lower-extremity movement using clinically friendly movement assessments, such as rubrics and 2D measures. Assessments used clinically or for research should have acceptable measurement properties, such as reliability and validity. However, the literature on reliability and validity of movement assessments to analyze jump landings has not been summarized.

OBJECTIVE

To systematically review measurement properties of rubrics and 2D measurements that aim to classify movement quality during jump landings.

EVIDENCE ACQUISITION

The search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. The search was performed in PubMed, SPORTDiscus, and Web of Science databases. The COnsensus-based Standards for the selection of health Measurement INstruments multiphase procedure was used to extract relevant data, evaluate methodological quality of each study, score the results of each movement assessment, and synthesize the evidence.

EVIDENCE SYNTHESIS

Twenty-two studies were included after applying eligibility criteria. Reliability and construct validity of the landing error scoring system were acceptable. Criterion validity of 2D knee flexion angle and medial knee displacement is acceptable. Reliability of 2D knee ankle separation ratio and knee frontal plane projection angle are acceptable.

CONCLUSION

The landing error scoring system is a valid way to determine poor movement quality and injury risk. Measures of 2D knee flexion angle and medial knee displacement are valid alternatives for 3D knee flexion angle and knee abduction moment, respectively. Knee ankle separation ratio and knee frontal plane projection angle are reliable but lack validity justifying their clinical use.

Optimizing Rehabilitation and Return to Sport in Athletes With Anterior Knee Pain Using a Biomechanical Perspective

Anterior knee pain represents one of the most common athletic knee conditions and arguably also one of the most complex. The patellofemoral joint is at the center of several forces, and alterations in any of these force vectors due to muscular imbalance, soft-tissue tightness or laxity, and altered functional movement patterns can all combine to create a painful anterior knee. While typically anterior knee pain is not a surgical entity, the orthopaedic surgeon with an understanding of these biomechanical intricacies is best positioned to provide comprehensive evidence-based care for the patient with anterior knee pain.

Level of Evidence

V, expert opinion.

Brain Activity During Experimental Knee Pain and Its Relationship With Kinesiophobia in Patients With Patellofemoral Pain: A Preliminary Functional Magnetic Resonance Imaging Investigation

Context: The etiology of patellofemoral pain has remained elusive, potentially due to an incomplete understanding of how pain, motor control, and kinesiophobia disrupt central nervous system functioning. Objective: To directly evaluate brain activity during experimental knee pain and its relationship to kinesiophobia in patients with patellofemoral pain. Design: Cross-sectional. Methods: Young females clinically diagnosed with patellofemoral pain (n = 14; 14.4 [3.3] y; body mass index = 22.4 [3.8]; height = 1.61 [0.1] m; body mass = 58.4 [12.7] kg). A modified Clarke test (experimental pain condition with noxious induction via patella pressure and quadriceps contraction) was administered to the nondominant knee (to minimize limb dominance confounds) of patients during brain functional magnetic resonance imaging (fMRI) acquisition. Patients also completed a quadriceps contraction without application of external pressure (control contraction). Kinesiophobia was measured using the Tampa Scale of Kinesiophobia. The fMRI analyses assessed brain activation during the modified Clarke test and control contraction and assessed relationships between task-induced brain activity and kinesiophobia. Standard processing for neuroimaging and appropriate cluster-wise statistical thresholds to determine significance were applied to the fMRI data (z > 3.1, P < .05). Results: The fMRI revealed widespread neural activation in the frontal, parietal, and occipital lobes, and cerebellum during the modified Clarke test (all zs > 4.4, all Ps < .04), whereas neural activation was localized primarily to frontal and cerebellar regions during the control contraction test (all zs > 4.4, all Ps < .01). Greater kinesiophobia was positively associated with greater activity in the cerebello-frontal network for the modified Clarke test (all zs > 5.0, all Ps < .01), but no relationships between kinesiophobia and brain activity were observed for the control contraction test (all zs < 3.1, all Ps > .05). Conclusions: Our novel experimental knee pain condition was associated with alterations in central nociceptive processing. These findings may provide novel complementary pathways for targeted restoration of patient function.

A 2D video-analysis scoring system of 90° change of direction technique identifies football players with high knee abduction moment

PURPOSE

Abnormal joint biomechanics and poor neuromuscular control are modifiable risk factors for Anterior Cruciate Ligament (ACL) injury. Although 3D motion capture is the gold standard for the biomechanical evaluation of high-speed multidirectional movements, 2D video analysis is a growing-interest alternative because of its higher cost-effectiveness and interpretability. The aim of the present study was to explore the possible association between a 2D evaluation of a 90° change of direction (COD) and the KAM measured with gold standard 3D motion analysis.

METHODS

Thirty-four competitive football (soccer) players (age 22.8 ± 4.1, 18 male and 16 females) were enrolled. Each athlete performed a series of pre-planned 90° COD at the maximum speed possible in a laboratory equipped with artificial turf. 3D motion analysis was recorded using 10 stereophotogrammetric cameras, a force platform, and three high-speed cameras. The 2D evaluation was performed through a scoring system based on the video analysis of frontal and sagittal plane joint kinematics. Five scoring criteria were adopted: limb stability (LS), pelvis stability (PS), trunk stability (TS), shock absorption (SA), and movement strategy (MS). For each criterion, a sub-score of 0/2 (non-adequate), 1/2 (partially adequate), or 2/2 (adequate) was attributed to the movement, based on objective measurements. The intra-rater and inter-rater reliability were calculated for each criterion and the total score. The Knee Abduction Moment (KAM) was extracted from the 3D motion analysis and grouped according to the results of the 2D evaluation.

RESULTS

Excellent intra-rater reliability (ICC > 0.88) and good-to-excellent inter-rater reliability (ICC 0.68-0.92) were found. Significantly higher KAM was found for athletes obtaining a 0/2 score compared to those obtaining a 2/2 score in all the sub-criteria and the total score (20-47% higher, p < 0.05). The total score and the LS score showed the best discriminative power between the three groups.

CONCLUSION

The 2D video-analysis scoring system here described was a simple and effective tool to discriminate athletes with high and low KAM in the assessment of a 90° COD and could be a potential method to identify athletes at high risk of non-contact ACL injury.

LEVEL OF EVIDENCE

IV.

Alterations in the Functional Knee Alignment Are Not an Effective Strategy to Modify the Mediolateral Distribution of Knee Forces During Closed Kinetic Chain Exercises

Pain felt while performing rehabilitation exercises could be a reason for the low adherence of knee osteoarthritis patients to physical rehabilitation. Reducing compressive forces on the most affected knee regions may help to mitigate the pain. Knee frontal plane positioning with respect to pelvis and foot (functional knee alignment) has been shown to modify the mediolateral distribution of the tibiofemoral joint contact force in walking. Hence, different functional knee alignments could be potentially used to modify joint loading during rehabilitation exercises. The aim was to understand whether utilizing different alignments is an effective strategy to unload specific knee areas while performing rehabilitation exercises. Eight healthy volunteers performed 5 exercises with neutral, medial, and lateral knee alignment. A musculoskeletal model was modified for improved prediction of tibiofemoral contact forces and used to evaluate knee joint kinematics, moments, and contact forces. Functional knee alignment had only a small and inconsistent effect on the mediolateral distribution joint contact force. Moreover, the magnitude of tibiofemoral and patellofemoral contact forces, knee moments, and measured muscle activities was not significantly affected by the alignment. Our results suggest that altering the functional knee alignment is not an effective strategy to unload specific knee regions in physical rehabilitation.

Vertical Drop Jump Biomechanics of Patients With a 3- to 10-Year History of Youth Sport-Related Anterior Cruciate Ligament Reconstruction

Background

A better understanding of movement biomechanics after anterior cruciate ligament reconstruction (ACLR) could inform injury prevention, knee injury rehabilitation, and osteoarthritis prevention strategies.

Purpose

To investigate differences in vertical drop jump (VDJ) biomechanics between patients with a 3- to 10-year history of youth sport-related ACLR and uninjured peers of a similar age, sex, and sport.

Study Design

Cross-sectional study. Level of evidence III.

Methods

Lower limb kinematics and bilateral ground-reaction forces (GRFs) were recorded for participants performing 10 VDJs. Joint angles and GRF data were analyzed, and statistical analysis was performed using 2 multivariate models. Dependent variables included sagittal (ankle, knee, and hip) and coronal (knee and hip) angles at initial contact and maximum knee flexion, the rate of change of coronal knee angles (35%-90% of the support phase; ie, slopes of linear regression lines), and vertical and mediolateral GRFs (normalized to body weight [BW]). Fixed effects included group, sex, and time since injury. Participant clusters, defined by sex and sport, were considered as random effects.

Results

Participants included 48 patients with a history of ACLR and 48 uninjured age-, sex-, and sport-matched controls (median age, 22 years [range, 18-26 years]; 67% female). Patients with ACLR demonstrated steeper negative coronal knee angle slopes (β = -0.04 deg/% [95% CI, -0.07 to -0.00 deg/%]; P = .025). A longer time since injury was associated with reduced knee flexion (β = -0.2° [95% CI, -0.3° to -0.0°]; P = .014) and hip flexion (β = -0.1° [95% CI, -0.2° to -0.0°]; P = .018). Regardless of ACLR history, women displayed greater knee valgus at initial contact (β = 2.1° [95% CI, 0.4° to 3.8°]; P = .017), greater coronal knee angle slopes (β = 0.05 deg/% [95% CI, 0.02 to 0.09 deg/%]; P = .004), and larger vertical GRFs (landing: β = -0.34 BW [95% CI, -0.61 to -0.07 BW]; P = .014) (pushoff: β = -0.20 BW [95% CI, -0.32 to -0.08 BW]; P = .001).

Conclusion

Women and patients with a 3- to 10-year history of ACLR demonstrated VDJ biomechanics that may be associated with knee motion control challenges.

Clinical Relevance

It is important to consider knee motion control during activities such as VDJs when developing injury prevention and rehabilitation interventions aimed at improving joint health after youth sport-related ACLR.

Developmental Training Model for the Sport Specialized Youth Athlete: A Dynamic Strategy for Individualizing Load-Response During Maturation

CONTEXT

Most available data on athletic development training models focus on adult or professional athletes, where increasing workload capacity and performance is a primary goal. Development pathways in youth athletes generally emphasize multisport participation rather than sport specialization to optimize motor skill acquisition and to minimize injury risk. Other models emphasize the need for accumulation of sport- and skill-specific hours to develop elite-level status. Despite recommendations against sport specialization, many youth athletes still specialize and need guidance on training and competition. Medical and sport professionals also recommend progressive, gradual increases in workloads to enhance resilience to the demands of high-level competition. There is no accepted model of risk stratification and return to play for training a specialized youth athlete through periods of injury and maturation. In this review, we present individualized training models for specialized youth athletes that (1) prioritize performance for healthy, resilient youth athletes and (2) are adaptable through vulnerable maturational periods and injury.

EVIDENCE ACQUISITION

Nonsystematic review with critical appraisal of existing literature.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

A number of factors must be considered when developing training programs for young athletes: (1) the effect of sport specialization on athlete development and injury, (2) biological maturation, (3) motor and coordination deficits in specialized youth athletes, and (4) workload progressions and response to load.

CONCLUSION

Load-sensitive athletes with multiple risk factors may need medical evaluation, frequent monitoring, and a program designed to restore local tissue and sport-specific capacity. Load-naive athletes, who are often skeletally immature, will likely benefit from serial monitoring and should train and compete with caution, while load-tolerant athletes may only need occasional monitoring and progress to optimum loads.

STRENGTH OF RECOMMENDATION TAXONOMY (SORT)

B.

Visual assessment of dynamic knee joint alignment in patients with patellofemoral pain: an agreement study

Background

Assessment of knee kinematics plays an important role in the clinical examination of patients with patellofemoral pain (PFP). There is evidence that visual assessments are reliable in healthy subjects, but there is a lack of evidence in injured populations. The purpose of this study was to examine the intra- and interrater agreement in the visual assessment of dynamic knee joint alignment in patients with PFP.

Methods

The study was a cross-sectional agreement study. Sixty participants (42 females) were included. We assessed the intra- and interrater agreement of two functional tests: The single leg squat (SLS) and the forward lunge (FL). One investigator scored the movement according to preset criteria while video recording the movement for retest. Moreover, the performance was scored by another investigator using the video recording. Agreement was assessed using weighted kappa statistics.

Results

The intrarater agreement ranged from moderate to good (Kappa 0.58 (FL) to 0.70 (SLS)) whereas the interrater agreement ranged from fair to moderate (Kappa 0.22 (SLS) to 0.50 (FL)).

Conclusion

The agreement within raters was better than between raters, which suggests that assessments should preferably be performed by the same tester in research and in a clinical setting, e.g., to evaluate any treatment effect. We promote FL as a reliable clinical tool for evaluating dynamic knee alignment, since it shows equally good intra- and interrater agreement, and it is an inexpensive and easy method to use.

Comparing shallow, deep, and transfer learning in predicting joint moments in running

Joint moments are commonly calculated in biomechanics research and provide an indirect measure of muscular behaviors and joint loads. However, joint moments cannot be easily quantified clinically or in the field, primarily due to challenges measuring ground reaction forces outside the laboratory. The present study aimed to compare the accuracy of three different machine learning (ML) techniques - functional regression [ ML_fregress ], a deep neural network (DNN) built from scratch [ ML_DNN ], and transfer learning [ ML_TL ], in predicting joint moments during running. Data for this study came from an open-source dataset and two studies on running with and without external loads. Three-dimensional (3D) joint moments of the hip, knee, and ankle, were derived using inverse dynamics. 3D joint angle, velocity, and acceleration of the three joints served as predictors for each of the three ML techniques. Prediction performance was generally the best using ML_DNN, and the worse using ML_fregress. Absolute predictive performance was the best for sagittal plane moments, which ranged from a RMSE of 0.16 Nm/kg at the ankle using ML_DNN, to a RMSE of 0.49Nm/kg at the knee using ML_fregress. ML_DNN resulted in the greatest improvement in relative prediction performance (relRMSE) by 20% compared to ML_fregress for the ankle adduction-abduction moment. DNN with or without transfer learning was superior in predicting joint moments using kinematic inputs compared to functional regression. Synergizing ML with kinematic inputs has the potential to solve the constraints of obtaining high fidelity biomechanics data normally only possible during laboratory studies.

Anterior knee pain independently alters landing and jumping biomechanics

Background Biomechanical effects of anterior knee pain are difficult to distinguish from effects of other factors also related to knee injury (e.g., joint effusion). The purpose of this study was to evaluate independent effects of anterior knee pain on landing and jumping biomechanics. Methods Thirteen healthy participants performed a land and jump movement task, under three experimental conditions (pre-pain, pain, and post-pain), during one data collection session. One 1-ml injection of hypertonic saline into the infrapatellar fat pad was used to induce experimental anterior knee pain during the pain condition. Participant-perceived anterior knee pain was measured every 2 min throughout data collection. Landing and jumping biomechanics were measured and compared between the experimental conditions using a functional statistical approach. Findings The aforementioned injection increased mean participant-perceived anterior knee pain, from zero during the pre-pain condition to 2.6 ± 0.71 cm during the pain condition. Vertical ground reaction force, knee flexion angle, and internal knee extension moment decreased by approximately 0.100 body weights, 3°, and 0.010 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Conversely, hip flexion angle and internal hip extension moment increased by approximately 3° and 0.006 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Several biomechanical changes persisted after anterior knee pain abatement (the post-pain condition). Interpretation Anterior knee pain alters landing and jumping biomechanics, independent of other injury-related factors. These altered biomechanics likely change knee joint loading patterns and might increase risk for chronic knee joint injury and/or pathology.

Drop Landing Biomechanics in Individuals With and Without a Concussion History

Research has identified an increased risk of lower extremity injury postconcussion, which may be due to aberrant biomechanics during dynamic tasks. The purpose of this study was to compare the drop landing biomechanics between individuals with and without a concussion history. Twenty-five individuals with and 25 without a concussion history were matched on age (±3 y), sex, and body mass index (±1 kg/m2). Three-dimensional landing biomechanics were recorded to obtain dependent variables (peak vertical ground reaction force, loading rate, knee flexion angle and external moment, knee abduction angle and external moment, and knee flexion and abduction angle at ground contact). A 1-way multivariate analysis of variance compared outcomes between groups. There was no difference in drop landing biomechanics between individuals with and without a concussion history (F10,39 = 0.460, P = .877, Wilk Λ= .918). There was an effect of time since concussion on knee flexion characteristics. Time since most recent concussion explained a significant amount of variation in both peak (ΔR2 = .177, β = -0.305, ΔP = .046) and initial ground contact (ΔR2 = .292, β = -0.204, ΔP = .008) knee flexion angle after covarying for sex and body mass index. Therefore, time since concussion should be considered when evaluating biomechanical patterns.

What did the ankle say to the knee? Estimating knee dynamics during landing - A systematic review and meta-analysis

BACKGROUND

Landing-based measures of the knee are often used to assess risk of anterior cruciate ligament (ACL) injury and inform prevention strategies. There is less understanding of the ankle's influence on knee measures during landing.

OBJECTIVE

1. Examine interactions of dynamic ankle measures alongside various subject and task characteristics on knee dynamics in vertical landing and 2. Determine whether ankle measures alone can estimate dynamic knee measures associated with ACL injury risk.

DESIGN

Systematic review and meta-analysis.

METHODS

Electronic databases Medline, EMBASE, CINAHL, Web of Science and Cochrane were screened for studies that included measurement of initial contact angles and internal joint moments of both the ankle and knee during landing in uninjured individuals.

RESULTS

28 studies were included for analysis. Using 1144 landing trials from 859 individuals, RRelief F algorithm ranked dynamic ankle measures more important than landing task and subject characteristics in estimating knee dynamics. An adaptive boosting model using four dynamic ankle measures accurately estimated knee extension (R² = 0.738, RMSE = 3.65) and knee abduction (R² = 0.999, RMSE = 0.06) at initial contact and peak knee extension moment (R² = 0.988, RMSE = 0.13) and peak knee adduction moment (R² = 1, RMSE = 0.00).

CONCLUSIONS

Dynamic ankle measures can accurately estimate initial contact angles and peak moments of the knee in vertical landing, regardless of landing task or individual subject characteristics. This study provides a theoretical basis for the importance of the ankle in ACL injury prevention.

The effects of hip- and ankle-focused exercise intervention on dynamic knee valgus: a systematic review

BACKGROUND

A range of non-contact injuries such as anterior cruciate ligament tear, and patellofemoral pain syndrome are caused by disordered knee joint loading from excessive dynamic knee valgus (DKV). Previous systematic reviews showed that DKV could be modified through the influence of hip strength and ankle range of motion. Therefore, the purpose of this systematic review was to examine the effects of exercise intervention which involved either top-down or bottom-up kinetic chains on minimizing DKV in male and female adults and adolescents, with and without existing knee pain.

METHODOLOGY

Electronic searches were conducted in SAGE, Science Direct, SCOPUS, and Pubmed. The search strategy consisted of medical subject headings and free-text search keywords, synonyms and variations of 'exercise intervention,' 'knee alignment,' 'dynamic knee valgus', 'knee abduction' that were merged via the Boolean operator 'AND' and 'OR'. The search was conducted on full-text journals that documented the impact of the exercise intervention program involving either the bottom-up or top-down DKV mechanism on the knee kinematics. Furthermore, exercise intervention in this review should last at least one week which included two or three sessions per week. This review also considered both men and women of all ages with a healthy or symptomatic knee problem. The risk of bias of the included studies was assessed by Cochrane risk assessment tool. The protocol of this review was registered at PROSPERO (registration number: CRD42021219121).

RESULTS

Ten studies with a total of 423 participants (male = 22.7%, female = 77.3%; adults = 249, adolescents = 123; pre-adolescent = 51) met the inclusion criteria of this review. Seven studies showed the significant effects of the exercise intervention program (range from two weeks to ten weeks) on reducing DKV. The exercise training in these seven studies focused on muscle groups directly attached to the knee joint such as hamstrings and gastrocnemius. The remaining three studies did not show significant improvement in DKV after the exercise intervention (range between eight weeks to twelve weeks) probably because they focused on trunk and back muscles instead of muscles crossing the knee joint.

CONCLUSION

Exercises targeting specific knee-joint muscles, either from top-down or bottom-up kinetic chain, are likely to reduce DKV formation. These results may assist athletes and coaches to develop effective exercise program that could minimize DKV and ultimately prevent lower limb injuries.

Asymmetries in Dynamic Valgus Index After Anterior Cruciate Ligament Reconstruction: A Proof-of-Concept Study

Individuals with anterior cruciate ligament reconstruction (ACLR) are at a higher risk for subsequent anterior cruciate ligament (ACL) tears. Risk factors for ACL injuries likely involve a combination of anatomical, biomechanical, and neuromuscular factors. Dynamic knee valgus has been indicated as a possible biomechanical factor for future ACL injuries. Given that knee valgus is often accompanied by contralateral pelvic drop during single-leg activities, a dynamic valgus index (DVI) that quantifies combined kinematics of the knee and hip in the frontal plane has recently been developed. As the premise of asymmetrical DVI between limbs in the ACLR population has not been examined, this cross-sectional study was conducted with the aim to compare DVI between individuals with ACLR and healthy controls. Videos were taken for 12 participants with ACLR and 20 healthy controls when they performed single-leg hopping. One-way ANOVA revealed a higher DVI in the injured limb of the ACLR group when compared to their non-injured limb and to the healthy limb of the control group. As our data showed increased DVI in the injured limb of the ACLR group, the DVI approach accounting for hip and knee kinematics may be used to identify frontal plane movement deficits during single-leg hopping in individuals with ACLR.

Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing

BACKGROUND

Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear.

HYPOTHESIS

We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion).

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk.

RESULTS

For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion (r² = 0.21, P = 0.05), 1.2° decrease in peak knee flexion angles (r² = 0.37, P = 0.01), 0.9° decrease in knee flexion excursion (r² = 0.40, P = 0.004), 0.002 N·m·N^-1·cm^-1 decrease in hip extensor work (r² = 0.28, P = 0.02), and 0.001 N·m·N^-1·cm^-1 decrease in knee extensor work (r² = 0.21, P = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles (r² = 0.26, P = 0.03) and 0.01 N·m·N^-1·cm^-1 lesser knee extensor work (r² = 0.25, P = 0.03).

CONCLUSION

Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury.

CLINICAL RELEVANCE

While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.

Increased femoral antetorsion correlates with higher degrees of lateral retropatellar cartilage degeneration, further accentuated in genu valgum

PURPOSE

The role of increased femoral antetorsion (femAT) as a contributor to patellofemoral (PF) osteoarthritis (OA) is unknown. The purpose of this study was to investigate whether increased femAT was associated with advanced cartilage degeneration in the lateral PF joint.

METHODS

Patients who underwent complete radiographic workup for surgical intervention due to OA in any knee joint compartment were included. Cartilage morphology according to the International Cartilage Repair Society (ICRS) cartilage lesion classification system in the PF joint, femoral and tibial torsion, frontal leg axis, and tibial tuberosity-trochlear groove (TT-TG) distance were assessed. Increased femAT was defined as  > 20° according to previous reports.

RESULTS

A total of 144 patients were included. Ninety-seven patients had a femAT of  < 20° and 45 of  > 20°. A significant odds ratio (OR) was found for lateral retropatellar (OR 3.5; p = 0.02) ICRS grade 3 and 4 cartilage degeneration and increased femAT  ≥ 20°. In the medial PF compartment, increased femAT had an inverse effect (OR 0.16; p = 0.01). No significant ORs were found for TT-TG distance, tibial torsion, or leg axis. The lateral retropatellar ICRS grade showed a linear correlation to increased femAT values. In valgus knees, isolated lateral PF OA had an even more pronounced correlation to increased femAT (p = 0.004).

CONCLUSION

Increased femAT showed higher grades of lateral retropatellar cartilage degeneration, which was even more pronounced in valgus knees.

LEVEL OF EVIDENCE

Cohort study: Level III.

The non-sagittal knee moment vector identifies 'at risk' individuals that the knee abduction moment alone does not

Multi-planar forces and moments are known to injure the anterior cruciate ligament (ACL). In ACL injury risk studies, however, the uni-planar frontal plane external knee abduction moment is frequently studied in isolation. This study aimed to determine if the frontal plane knee moment (KM-Y) could classify all individuals crossing a risk threshold compared to those classified by a multi-planar non-sagittal knee moment vector (KM-YZ). Recreationally active females completed three sports tasks-drop vertical jumps, single-leg drop vertical jumps and planned sidesteps. Peak knee abduction moments and peak non-sagittal resultant knee moments were obtained for each task, and a risk threshold of the sample mean plus 1.6 standard deviations was used for classification. A sensitivity analysis of the threshold from 1-2 standard deviations was also conducted. KM-Y did not identify all participants who crossed the risk threshold as the non-sagittal moment identified unique individuals. This result was consistent across tasks and threshold sensitivities. Analysing the peak uni-planar knee abduction moment alone is therefore likely overly reductionist, as this study demonstrates that a KM-YZ threshold identifies 'at risk' individuals that a KM-Y threshold does not. Multi-planar moment metrics such as KM-YZ may help facilitate the development of screening protocols across multiple tasks.

Effects of Overweight and Obesity on Running Mechanics in Children

PURPOSE

The purpose of this study is to determine differences in running mechanics between healthy weight (HW) children and children classified as OW/OB.

METHODS

Forty-two children (17 OW/OB, 25 HW) ran overground while kinematic and kinetic data were recorded using a motion capture system and force plate. Kinematic variables of interest included stance time, step length, and frontal and sagittal plane joint angles and excursions at the hip, knee, and ankle. Kinetic variables of interest included ground reaction forces and hip, knee, and ankle moments in the sagittal and frontal planes.

RESULTS

The OW/OB group spent more time in stance, took shorter steps, displayed less hip flexion during the first half of stance, had greater ankle inversion at foot strike, had greater knee abduction throughout stance, and had smaller knee flexion, knee adduction, and hip adduction excursions. In comparing unscaled ground reaction forces, the OW/OB group displayed greater peak vertical force, vertical impact peaks, and vertical loading rates. The OW/OB group also displayed greater unscaled plantar and dorsiflexion moments, knee flexion and extension moments, ankle inversion moments, and knee and hip abduction moments.

CONCLUSION

These data suggest that increased body weight in children is associated with changes in running mechanics. Higher joint moments and ground reaction forces may indicate increased injury risk or the development of joint degeneration among overweight/obese children.

Visuomotor reaction time difference between patellofemoral pain syndrome and healthy individuals: Cross-sectional study

OBJECTIVE

Although many studies indicated a decreased reaction time in post-traumatic complaints including ACL injury, no study has been devoted to measure reaction time in patients with patellofemoral pain syndrome (PFPS). The purpose of the present study was to compare the visuomotor reaction time between PFPS and healthy individuals.

METHODS

Twenty five patients with PFPS (20 women and 5 men, mean age 29.28 years, SD 5.59) and 25 healthy controls (19 women, 6 men, mean age 29.32, years SD 5.30) were recruited in the present study. The dependent variables were upper extremity reaction time, upper extremity error rate, knee extension reaction time in both involved and non-involved legs, plantar flexion reaction time in both involved and non-involved legs.

RESULTS

The results of one-way multiple analysis of variance showed that patients with PFPS had slower upper extremity reaction time (P=0.047, Effect size (ES)=0.39) and plantar flexion reaction time (symptomatic side) (P<0.001, ES=0.77) as compared with healthy control. The symptomatic knee extension reaction time was slower than the healthy matched leg, but this difference was not statistically significant (P=0.296, ES= 0.19).

CONCLUSION

The present study suggests that the reaction time might be considered as a factor associated with PFPS.

Review of musculoskeletal modelling in a clinical setting: Current use in rehabilitation design, surgical decision making and healthcare interventions

BACKGROUND

Musculoskeletal modelling is a common means by which to non-invasively analyse movement. Such models have largely been used to observe function in both healthy and patient populations. However, utility in a clinical environment is largely unknown. The aim of this review was to explore existing uses of musculoskeletal models as a clinical intervention, or decision-making, tool.

METHODS

A literature search was performed using PubMed and Scopus to find articles published since 2010 and relating to musculoskeletal modelling and joint and muscle forces.

FINDINGS

4662 abstracts were found, of which 39 relevant articles were reviewed. Journal articles were categorised into 5 distinct groups: non-surgical treatment, orthoses assessment, surgical decision making, surgical intervention assessment and rehabilitation regime assessment. All reviewed articles were authored by collaborations between clinicians and engineers/modellers. Current uses included insight into the development of osteoarthritis, identifying candidates for hamstring lengthening surgery, and the assessment of exercise programmes to reduce joint damage.

INTERPRETATION

There is little evidence showing the use of musculoskeletal modelling as a tool for patient care, despite the ability to assess long-term joint loading and muscle overuse during functional activities, as well as clinical decision making to avoid unfavourable treatment outcomes. Continued collaboration between model developers should aim to create clinically-friendly models which can be used with minimal input and experience by healthcare professionals to determine surgical necessity and suitability for rehabilitation regimes, and in the assessment of orthotic devices.

MOVEMENT PATTERNS DIFFER BETWEEN ATHLETES AFTER SPORT-RELATED CONCUSSION COMPARED TO HEALTHY CONTROLS DURING JUMP LANDING TASK

CONTEXT

A relationship between a positive history of sport-related concussion (SRC) and lower extremity (LE) injury has been well established in the literature.

OBJECTIVE

The purpose of this study was to determine if biomechanical differences exist during a double limb jump landing (DLJ) between athletes who had been released for return to play after SRC and healthy matched controls (Healthy).

DESIGN

Cross-Sectional Study Setting: Health system-based Outpatient Sports Medicine Center Participants: 21 participants (16.33±12.7 days out from being released to return to sport after SRC) (age: 15.38±1.77; height: 169.23±8.59; mass: 63.43±7.39) were compared to 21 age, sex, activity-matched healthy controls (age: 15.36±1.73; height: 169.92±11.1; mass: 65.62±12.08). No significant differences existed between groups for descriptive data.

MAIN OUTCOME MEASURE(S)

Biomechanical performance during DLJ was assessed using Motion Capture System and force plates. The average of five consecutive trials was used to calculate lower extremity joint kinetic and kinematics. Variables of interest included internal knee extension moment, internal varus moment, and total sagittal plane knee displacement for both the dominant and non-dominant limbs. Independent t-tests were performed to examine the differences between SRC and Healthy groups for variables of interest.

RESULTS

The SRC group demonstrated greater internal knee extension moments on their dominant (KEDomDiff=-.028±.009; p=.003) and non-dominant (KENonDomDiff=-.018±.007, p=.019) limbs. The SRC group also demonstrated greater internal varus moments on their dominant (VDomDiff=.012±.004, p=.005) and non-dominant (VNonDomDiff=.010±.003, p=.005) limbs. For sagittal plane knee displacement, the SRC group demonstrated less knee flexion displacement on their dominant (DispDomDiff=-12.56±4.67, p=.011) but not their non-dominant limb (DispNonDomDiff=-8.30±4.91, p=.099).

CONCLUSIONS

Athletes who have been released for return to sport after SRC land in greater knee valgus compared to healthy matched controls.

Electromyographic and kinematic analysis of females with excessive medial knee displacement in the overhead squat

Dynamic knee valgus is a multi-planar motion that has been associated with anterior cruciate ligament injuries and patellofemoral pain syndrome. Clinical assessment of dynamic knee valgus is usually performed through visual appearance of medial knee displacement (MKD) during the overhead squat. The aim of this study is to identify the kinematic and neuromuscular parameters associated with MKD. Twenty-two females performed an overhead squat and were assigned to the control group (n = 14) or the MKD group (n = 8). Electromyography and kinematic data of the lower extremity were collected. We observed MKD to exhibit greater muscle activity in the following muscles: adductor magnus, biceps femoris, vastus lateralis and vastus medialis muscles during the eccentric phase of the overhead squat. No group differences were observed during the concentric phase. Regarding the kinematics, the MKD group showed higher knee internal rotation and, knee abduction and ankle abduction, compared to controls. The combined information from the muscle activity results and kinematics of squat helps to explain the occurrence of excessive medial knee displacement and, hence, providing relevant information for health professionals to address this injury risk factor.

Injury Profile in Women's Football: A Systematic Review and Meta-Analysis

BACKGROUND

Football is the most popular sport among women; however, little is known about the injury profile in this population. This information would help design tailored injury risk mitigation strategies that may make football safer for women.

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis of epidemiological data of injuries in women´s football.

METHODS

A systematic review following PRISMA guidelines was performed up to January 2020 in PubMed, Web of Science, Sportdiscus and the Cochrane Library databases. Twenty-two studies reporting the incidence of injuries in women football were analysed. Two reviewers independently extracted data (intraclass correlation coefficient [ICC] for inter-reviewer reliability = 0.87) and assessed study quality using the STROBE statement, GRADE approach, Newcastle Ottawa Scale and Downs and Black assessment tools. Studies were combined in pooled analyses (injury incidence and injury proportion) using a Poisson random effects regression model.

RESULTS

The overall incidence of injuries in female football players was 6.1 injuries/1000 h of exposure. Match injury incidence (19.2 injuries/1000 h of exposure) was almost six times higher than training injury incidence rate (3.5 injuries/1000 h of exposure). Lower extremity injuries had the highest incidence rates (4.8 injuries/1000 h of exposure). The most common types of injuries were muscle/tendon (1.8 injuries/1000 h of exposure) and joint (non-bone) and ligament (1.5 injuries/1000 h of exposure), which were frequently associated with traumatic incidents. Slight/minimal injuries (1-3 days of time loss) were the most common. The incidence rate of injuries during matches in the top five world ranking leagues was higher than the rest of the leagues (19.3 vs 10.7 injuries/1000 h of exposure, respectively). The weighted injury proportion was 1.1 (95% confidence interval = 0.6-1.7) whereby on average players sustained more than one injury per season.

CONCLUSIONS

Female football players are exposed to a substantial risk of sustaining injuries, especially during matches that require the highest level of performance. To markedly reduce overall injury burden, efforts should focus on introducing and evaluating preventative measures that target match specific dynamics to make football players more capable of responding to the challenges that they have to deal with during match play.

REGISTRATION

This systematic review was registered in the PROSPERO international prospective register of systematic reviews (ID = CRD42019118152).

The effectiveness of superimposed neuromuscular electrical stimulation combined with strengthening exercises on patellofemoral pain: A randomized controlled pilot trial

BACKGROUND

Patellofemoral pain (PFP) is one of the most common disorders of the knee. Neuromuscular electrical stimulation (NMES) is often assumed by clinicians to be an effective adjunctive therapy to quadriceps strengthening.

OBJECTIVE

The aim of this study was to assess the efficacy of superimposed NMES combined with strengthening exercises to improve the recovery of quadriceps strength and function in patients with PFP.

METHODS

This study was planned as a single blind randomized controlled pilot study. A total of twenty-seven patients diagnosed with PFP were randomly assigned into 2 groups. Patients received superimposed NMES in addition to the standardized program (Group I) or only the standardized program (Group II). The patients in both groups were treated 3 times a week for 6 weeks and followed at 12 weeks. Primary outcome measure was quadriceps isokinetic muscle strength. The changes in dependent variables before treatment, 6th, and 12th weeks were analyzed using a 2 × 3 mixed-model analysis of variance.

RESULTS

There were significant improvements in the within groups statistics of all parameters for both groups (p< 0.05). No differences in quadriceps strength, Kujala and Lysholm scores between groups were found at the different time points [F (2, 21) = 0.86; p= 0.12, F (2, 21) = 0.001; p= 0.97, F (2, 21) = 0.12; p= 0.73, respectively].

CONCLUSIONS

The results indicate that superimposed NMES combined with the standardized rehabilitation program has no clinically significant superiority to standardized rehabilitation program alone.

Effects of anterior cruciate ligament reconstruction on patellofemoral joint stress and lower extremity biomechanics at 12 weeks post-surgery and at time of return to sport in adolescent females

BACKGROUND

The purpose of this study was to examine kinematic and kinetic differences associated with patellofemoral pain after anterior cruciate ligament reconstruction between limbs at 12-week post-surgery and at time of return to sport.

METHOD

Twenty-four adolescent females completed 5 consecutive single leg squats on each limb at 12-weeks post-surgery and again during their RTS assessment. Peak knee extension moment, peak hip adduction angle, and patellofemoral joint stress at 45 degrees of knee flexion were calculated. Separate two by two repeated measures ANOVA were performed.

FINDINGS

There was a significant interaction (limb × time) for knee extension moment (p < 0.001). Surgical limb knee extension moment was significantly less than the non-surgical limb at return to sport (p < 0.001). At 12-weeks the surgical limb was significantly less than non-surgical limb (p < 0.001), additionally the surgical limb was significantly greater at time of return to sport than at 12 weeks (p < 0.001). There was a significant main effect of limb for hip adduction angle (p = 0.002). Surgical limb was significantly greater than non-surgical limb (Surgical = 9.84 (SE 1.53) degree, non-surgical = 4.79 (SE 1.01) degree). There was also a main effect of time and limb for patellofemoral joint stress. Return to sport was significantly greater than 12 weeks and the surgical limb was significantly less than non-surgical limb (Surgical = 4.93 (SE 0325) MPa, Nonsurgical = 5.29 (SE 0.30) MPa).

INTERPRETATION

The surgical limb of participants following ACL-R demonstrated variables that have been associated with the development of patellofemoral pain.

Utility of Kinetic and Kinematic Jumping and Landing Variables as Predictors of Injury Risk: A Systematic Review

Purpose

Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces, generate lower limb explosive power and maintain joint alignment. In order to identify risk factors that can be targeted through appropriate training interventions, it is necessary to establish which (scalar) objective kinetic, kinematic, and performance measures are most associated with lower-extremity injury.

Methods

Online searches of MEDLINE, SCOPUS, EBSCOHost, SPORTDiscus and PubMed databases were completed for all articles published before March 2020 in accordance with PRISMA guidelines.

Results

40 articles investigating nine jump-landing assessments were included in this review. The 79% of studies using drop jump (n = 14) observed an association with future injury, while only 8% of countermovement jump studies (n = 13) observed an association with injury risk. The 57% of studies using unilateral assessments found associations with risk of injury (n = 14). Studies using performance measures (jump height/distance) as outcome measure were only associated with injury risk in 30% of cases. However, those using kinetic and/or kinematic analyses (knee abduction moment, knee valgus angle, knee separation distance, peak ground reaction force) found associations with injury in 89% of studies.

Conclusion

The landing element of jump-landing assessments appears to be superior for identifying individuals at greater risk of injury; likely due to a closer representation of the injury mechanism. Consequently, jump-landing assessments that involve attenuation of impact forces such as the drop jump appear most suited for this purpose but should involve assessment of frontal plane knee motion and ground reaction forces.

Accuracy of the Region of Limb Stability in Predicting Risk for Lower Limb Injury

PURPOSE

This study aimed to determine whether a measure of lower limb segment stability derived from body-worn inertial measurement units can predict risk for lower limb musculoskeletal injury in Division I Collegiate Football Players (D1CFP).

METHODS

The region of limb stability (ROLS) values were collected in a cohort of D1CFP during preseason. ROLS is a measure of knee joint stability, defined by thigh and shank excursion (cm) in the anterior-posterior and medial-lateral direction during single limb stance. The ROLS symmetry index (SI) (%) is the ratio between lower limb ROLS values where 100% suggests absolute symmetry.

RESULTS

One-hundred and four D1CFP participated in this study and were divided into two groups: 1) no previous lower limb injury or no in-season injury (n = 70, "noninjured group") and 2) no previous lower limb injury, but in-season injury requiring surgery (n = 34, "injured group" group). The mean ± SD ROLS SI was 82.86% ± 14.75% and 65.58% ± 16.46% for the noninjured and injured group, respectively. Significant differences in ROLS SI were found between groups (P < 0.001). The ROLS SI demonstrated an area under the curve of 0.8 (P < 0.001; 95% confidence interval = 0.71-0.88) with an SE of 0.04, indicating that the ROLS SI has good predictive accuracy in detecting those healthy D1CFP at risk for lower limb injury resulting in surgery.

CONCLUSION

The ROLS SI was found to have good predictive accuracy in detecting individuals at risk for injury that were healthy and asymptomatic during preseason testing. Increase in thigh and shank excursions and/or decrease in SI between lower limbs may be a predictor of risk for future injury.

Prospective Frontal Plane Angles Used to Predict ACL Strain and Identify Those at High Risk for Sports-Related ACL Injury

Background:

Knee abduction moment during landing has been associated with anterior cruciate ligament (ACL) injury. However, accurately capturing this measurement is expensive and technically rigorous. Less complex variables that lend themselves to easier clinical integration are desirable.

Purpose:

To corroborate in vitro cadaveric simulation and in vivo knee abduction angles from landing tasks to allow for estimation of ACL strain in live participants during a landing task.

Study Design:

Descriptive laboratory study.

Methods:

A total of 205 female high school athletes previously underwent prospective 3-dimensional motion analysis and subsequent injury tracking. Differences in knee abduction angle between those who went on to develop ACL injury and healthy controls were assessed using Student t tests and receiver operating characteristic analysis. A total of 11 cadaveric specimens underwent mechanical impact simulation while instrumented to record ACL strain and knee abduction angle. Pearson correlation coefficients were calculated between these variables. The resultant linear regression model was used to estimate ACL strain in the 205 high school athletes based on their knee abduction angles.

Results:

Knee abduction angle was greater for athletes who went on to develop injury than for healthy controls (P < .01). Knee abduction angle at initial contact predicted ACL injury status with 78% sensitivity and 83% specificity, with a threshold of 4.6° of knee abduction. ACL strain was significantly correlated with knee abduction angle during cadaveric simulation (P < .01). Subsequent estimates of peak ACL strain in the high school athletes were greater for those who went on to injury (7.7-8.1% ± 1.5%) than for healthy controls (4.1-4.5% ± 3.6%) (P < .01).

Conclusion:

Knee abduction angle exhibited comparable reliability with knee abduction moment for ACL injury risk identification. Cadaveric simulation data can be extrapolated to estimate in vivo ACL strain. Athletes who went on to ACL injury exhibited greater knee abduction and greater ACL strain than did healthy controls during landing.

Clinical Relevance:

These important associations between the in vivo and cadaveric environments allow clinicians to estimate peak ACL strain from observed knee abduction angles. Neuromuscular control of knee abduction angle during dynamic tasks is imperative for knee joint health. The present associations are an important step toward the establishment of a minimal clinically important difference value for ACL strain during landing.

Limited Support for Trunk and Hip Deficits as Risk Factors for Athletic Knee Injuries: A Systematic Review With Meta-analysis and Best-Evidence Synthesis

OBJECTIVE

To determine whether neuromuscular deficits in trunk and hip-related function are risk factors for athletic knee injuries.

DESIGN

Etiology systematic review with meta-analysis.

LITERATURE SEARCH

Six online databases (MEDLINE, Web of Science, Embase, CINAHL, Scopus, and SPORTDiscus) were searched up to April 2019.

STUDY SELECTION CRITERIA

Studies assessing trunk and hip neuromuscular function as risk factors for knee injuries in healthy athletic populations were included.

DATA SYNTHESIS

Outcomes were synthesized quantitatively using meta-analysis of odds ratios, and qualitatively using best-evidence synthesis.

RESULTS

Twenty-one studies met the inclusion criteria. There was very low-certainty evidence that greater hip external rotation strength protected against knee injuries (odds ratio = 0.78; 95% confidence interval: 0.70, 0.87; P<.05). There was limited evidence that deficits in trunk proprioception and neuromuscular control, and the combination of excessive knee valgus and ipsilateral trunk angle when landing unilaterally from a jump, may be risk factors for knee injuries.

CONCLUSION

Most variables of trunk and hip function were not risk factors for injuries. Further research is required to confirm whether hip external rotation strength, trunk proprioception and neuromuscular control, and the combination of knee valgus angle and ipsilateral trunk control are risk factors for future knee injuries. J Orthop Sports Phys Ther 2020;50(9):476-489. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9705.

Comparison of Foot Kinematics and Foot Plantar Area and Pressure Among Five Different Closed Kinematic Tasks

BACKGROUND

Different closed kinematic tasks may present different magnitudes of knee abduction, foot pronation, and foot plantar pressure and area. Although there are plenty of studies comparing knee abduction between different tasks, the literature lacks information regarding differences in foot pronation and foot plantar pressure and area. We compared foot angular displacement in the frontal plane and foot plantar pressure and area among five closed kinematic tasks.

METHODS

Forefoot and rearfoot angular displacement and foot plantar pressure and area were collected in 30 participants while they performed the following tasks: stair descent, single-leg step down, single-leg squat, single-leg landing, and drop vertical jump. Repeated-measures analyses of variance were used to investigate differences between tasks with α = 0.05.

RESULTS

Single-leg squat and stair descent had increased foot total plantar area compared with single-leg landing (P = .005 versus .027; effect size [ES] = 0.66), drop vertical jump (P = .001 versus P = .001; ES = 0.38), and single-leg step down (P = .01 versus P = .007; ES = 0.43). Single-leg landing and single-leg step down had greater foot total plantar area compared with drop vertical jump (P = .026 versus P = .014; ES = 0.54). There were differences also in rearfoot and midfoot plantar area and pressure and forefoot plantar pressure.

CONCLUSIONS

Differences in foot-striking pattern, magnitude of ground reaction force, and task speed might explain these findings. Clinicians should consider these findings to improve decisions about tasks used during rehabilitation of patients with foot conditions.

The Association Between the Single Leg Hop Test and Lower-Extremity Injuries in Female Athletes: A Critically Appraised Topic

Clinical Scenario: Female college student-athletes (SA) often experience time loss from musculoskeletal injuries to the lower extremities. This can lead to lengthy rehabilitation, expensive medical bills, and declines in health-related quality of life. Identifying at-risk athletes prior to the start of an athletic season may allow coaches or athletic trainers to prescribe an injury prevention program. Clinical Question: In female college SA, are preseason single leg hop (SLH) scores associated with identifying those at risk for lower-extremity musculoskeletal injuries? Summary of Key Findings: Five prospective cohort studies in female SA scored athletes on the SLH prior to the start of the athletic sport season. One of 5 studies found an association of SLH with injury risk. An additional 2 studies found that the SLH as part of a battery of functional performance tests was associated with injury risk in some anatomic locations (eg, thigh/knee), but not overall injury risk. Clinical Bottom Line: Methodological limitations of the reviewed studies limits a final conclusion, and there is insufficient evidence to determine if the SLH should be used as a sole functional performance test to identify at-risk female SA; it may be useful as part of a battery of functional performance tests for female college SA. Strength of Recommendation: All studies were prospective cohort studies (level 3).

Adolescent psychological beliefs, but not parent beliefs, associated with pain and function in adolescents with patellofemoral pain

OBJECTIVES

The purpose of this study was to assess the association of adolescent and parent psychological beliefs with 1) self-reported functional ability, 2) pain and 3) objective measures of function.

STUDY DESIGN

Cross-sectional study.

SETTING

Pediatric Outpatient Hospital.

PARTICIPANTS

Eighty-six adolescents with patellofemoral pain (PFP) (14.6 ± 1.7 years old, 62% female) and 72 parents.

MAIN OUTCOME MEASURES

Patient questionnaires were used to describe pain, knee function, fear avoidance (Fear Avoidance Beliefs Questionnaire-Physical Activity; FABQ-PA), kinesiophobia (Tampa Scale for Kinesiophobia-11; TSK-11), and pain catastrophizing (Pain Catastrophizing Scale; PCS) in adolescents with PFP. Parents (n = 72) completed FABQ-PA, TSK-11, and PCS questionnaires. Hip and knee strength, quadriceps and dorsiflexion motion, the single-leg hop for distance and lateral-step down test measured physical performance.

RESULTS

Adolescent psychological beliefs were significantly associated with pain (FABQ-PA r = 0.33, and PCS r = 0.34), function (FABQ-PA r = -0.59,TSK-11 r = -0.33), hip strength (FABQ-PA r = -0.41, TSK-11 r = -0.32), and single leg hop for distance (FABQ-PA r = -0.38). Parent psychological beliefs were not associated with the adolescent's beliefs, pain or function.

CONCLUSIONS

Adolescent, but not parent, psychological beliefs were associated with pain, self-reported function and objective measures of function.

Decision Tree Learning Algorithm for Classifying Knee Injury Status Using Return-to-Activity Criteria

Anterior cruciate ligament (ACL) injury rates in female adolescents are increasing. Irrespective of treatment options, approximately 1/3 will suffer secondary ACL injuries following their return to activity (RTA). Despite this, there are no evidence-informed RTA guidelines to aid clinicians in deciding when this should occur. The first step towards these guidelines is to identify relevant and feasible measures to assess the functional status of these patients. The purpose of this study was therefore to evaluate tests frequently used to assess functional capacity following surgery using a Reduced Error Pruning Tree (REPT). Thirty-six healthy and forty-two ACLinjured adolescent females performed a series of functional tasks. Motion analysis along with spatiotemporal measures were used to extract thirty clinically relevant variables. The REPT reduced these variables down to two limb symmetry measures (maximum anterior hop and maximum lateral hop), capable of classifying injury status between the healthy and ACL injured participants with a 69% sensitivity, 78% specificity and kappa statistic of 0.464. We, therefore, conclude that the REPT model was able to evaluate functional capacity as it relates to injury status in adolescent females. We also recommend considering these variables when developing RTA assessments and guidelines.Clinical Relevance- Our results indicate that spatiotemporal measures may differentiate ACL-injured and healthy female adolescents with moderate confidence using a REPT. The identified tests may reasonably be added to the clinical evaluation process when evaluating functional capacity and readiness to return to activity.

Lower Extremity Biomechanics During a Drop-Vertical Jump and Muscle Strength in Women With Patellofemoral Pain

CONTEXT

Patellofemoral pain (PFP) is one of the most prevalent knee conditions observed in women. Current research suggests that individuals with PFP have altered muscle activity, kinematics, and kinetics during functional tasks. However, few authors have examined differences in lower extremity biomechanics in this population during the drop-vertical jump (DVJ).

OBJECTIVE

To determine how lower extremity electromyography, kinematics, and kinetics during a DVJ and lower extremity isometric strength differed between women with and those without PFP.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen healthy women (age = 20.23 ± 1.39 years, height = 169.32 ± 5.38 cm, mass = 67.73 ± 9.57 kg) and 15 women with PFP (age = 22.33 ± 3.49 years, height = 166.42 ± 6.01 cm, mass = 65.67 ± 13.75 kg).

INTERVENTION(S)

Three trials of a DVJ.

MAIN OUTCOME MEASURE(S)

Surface electromyography, kinematics, and kinetics were collected simultaneously during a DVJ. Lower extremity strength was measured isometrically. Independent-samples t tests were performed to assess group differences.

RESULTS

Normalized muscle activity in the vastus medialis (healthy group = 120.84 ± 80.73, PFP group = 235.84 ± 152.29), gluteus maximus (healthy group = 43.81 ± 65.63, PFP group = 13.37 ± 13.55), and biceps femoris (healthy group = 36.68 ± 62.71, PFP group = 11.04 ± 8.9) during the landing phase of the DVJ differed between groups. Compared with healthy women, those with PFP completed the DVJ with greater hip internal-rotation moment (0.04 ± 0.28 N/kg versus 0.06 ± 0.14 N/kg, respectively) and had decreased knee-flexion excursion (76.76° ± 7.50° versus PFP = 74.14° ± 19.85°, respectively); they took less time to reach peak trunk flexion (0.19 ± 0.01 seconds versus 0.19 ± 0.02 seconds, respectively) and lateral trunk flexion (0.12 ± 0.07 seconds versus 0.11 ± 0.04 seconds, respectively).

CONCLUSIONS

During the DVJ, women with PFP had increased hip internal-rotation moment and decreased knee-flexion excursion with less time to peak trunk flexion and lateral flexion. Muscle activation was increased in the vastus medialis but decreased in the gluteus maximus and biceps femoris. This suggests that altered motor-unit recruitment in the hip and thigh may result in changes in biomechanics during a DVJ that are often associated with an increased risk of injury.

The Affect of Patient Sex and Graft Type on Postoperative Functional Outcomes After Primary ACL Reconstruction

Background:

Graft choice in anterior cruciate ligament reconstruction (ACLR) and postoperative rehabilitation may affect strength recovery differently in men than women and therefore affect a timely and successful return to sport.

Purpose:

To compare knee extensor and flexor strength between men and women who underwent isolated ACLR with either patellar tendon or hamstring tendon (HST) autografts.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 166 patients (87 women, 79 men) with primary unilateral and uncomplicated ACLRs were recruited for participation. A total of 100 patients had bone–patellar tendon–bone (BPTB) autografts and 66 had HST autografts. At 6 months postoperatively, all patients completed the Tegner activity scale and International Knee Documentation Committee Subjective Knee Evaluation as well as underwent bilateral isokinetic (90 deg/s) tests of the knee extensor and flexor groups. Outcomes were recorded in a single session as part of a return-to-sport test battery. Surgical notes were obtained to determine the type of autograft and nerve block used at the time of ACLR.

Results:

There was a significant sex × graft type interaction for mass-normalized knee flexor torque (P = .017). Female patients with an HST graft had a significantly lower knee flexor torque compared with female patients with a BPTB graft (0.592 ± 0.49 N·m/kg vs 0.910 ± 0.24 N·m/kg; Cohen d [95% CI] = 0.91 [0.45, 1.36]). They also had a significantly lower knee flexor torque when compared with male patients with an HST graft (0.592 ± 0.49 N·m/kg vs 0.937 ± 0.35 N·m/kg; Cohen d [95% CI]= 0.88 [0.45, 1.31]). There were significant main effects for graft type with knee flexion (P = .001) and extension (P = .008) symmetry. Patients with a BPTB graft demonstrated lower knee extensor symmetry (65.7% ± 17.0%) and greater knee flexor symmetry (98.7% ± 18.0%) compared with patients with an HST graft (extension: 77.1% ± 32%, Cohen d [95% CI] = 0.47 [0.16, 0.79]; flexion: 82.9% ± 33.3%, Cohen d [95% CI] = 0.63 [0.31, 0.95]). We also observed a significant main effect for sex (P = .028) and graft type (P = .048) for mass-normalized knee extensor strength. Female participants and patients of either sex with BPTB grafts had lower knee extensor strength compared with male participants and patients with HST grafts, respectively.

Conclusion:

At approximately 6 months after ACLR, female patients reconstructed with HST autografts demonstrated weaker HST strength compared with female patients with a BPTB autograft. There were no differences in HST strength between graft types in male patients. Female patients appear to be recovering HST strength differently than male patients when using an HST autograft. These findings may have implications in surgical planning, postoperative rehabilitation, and return-to-sport decision making.

Individuals with patellofemoral pain syndrome have altered inter-leg force coordination

BACKGROUND

Patellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal disorders. Pain may be further exacerbated by atypical motor coordination strategies. It has been thought that low coordination variability may concentrate loads onto painful knee tissues.

RESEARCH QUESTION

To investigate if inter-limb force coordination is altered between individuals with and without PFPS.

METHODS

31 individuals (control = 17, PFPS = 14) performed bilateral vertical hopping, on two force plates at three frequencies (2.2, 2.6, 3.0 Hz). Uncontrolled manifold analysis (UCM) was used to provide an index of motor abundance (IMA) in the coordination of inter-limb forces to stabilize the two-limb's total force. UCM was applied to the study of forces in each plane (medial-lateral (ML), anterior-posterior (AP), vertical). Bayesian Functional Data Analysis was used for statistical inference. We calculated the mean (u) with 95 % credible interval (CrI) of the difference ΔIMA_con>PFPS between the two groups. We also calculated the probability PΔIMA_con>PFPS>0data).

RESULTS

Individuals with PFPS had the greatest significant decrement from controls at 6% of stance hopping at 2.6 Hz by a mean difference of -0.23 for ML GRF; at 19 % of stance hopping at 2.2 Hz by a mean difference of -0.14 for AP GRF; and 52 % of stance hopping at 2.6 Hz by a mean difference of -0.14 for vertical GRF. For vertical GRF, there was a > 0.95 probability that controls had greater IMA than individuals with PFPS hopping between 12-13% of stance at 2.2 Hz, and between 48-55% at 2.6 Hz.

SIGNIFICANCE

Individuals with PFPS have reduced inter-leg force coordination for impact force attenuation and body support, compared to asymptomatic controls. The present study provides insights into a plausible mechanism underpinning persistent knee pain which could be used in the development of novel rehabilitative approaches for individuals with PFPS.

Part II: Comparison of Crossfit-Related Injury Presenting to Sports Medicine Clinic by Sex and Age

OBJECTIVE

To examine CrossFit-related injuries based on sex and age.

DESIGN

Retrospective case series.

SETTING

A tertiary-level pediatric sports medicine clinic.

PARTICIPANTS

CrossFit athletes.

MAIN OUTCOME MEASURES

CrossFit-related injuries by sex (males vs females) and age groups (≤19 years vs >19 years) using a χ analysis with P = 0.05, odds ratio (OR), and 95% confidence interval (95% CI).

RESULTS

Among injured CrossFit athletes, female athletes sustained lower extremity injuries more frequently than male athletes (P = 0.011; OR, 2.65; 95% CI, 1.25-5.65). In observed CrossFit injuries, shoulder injuries were more frequently observed in male athletes compared with female athletes (P = 0.049; OR, 2.79; 95% CI, 0.98-7.95). Additionally, a greater proportion of CrossFit athletes aged 19 years and younger suffered trunk/spine injuries than those older than 19 years (P = 0.027; OR, 2.61; 95% CI, 1.10-6.21) in injured CrossFit athletes.

CONCLUSIONS

The current results indicated sex- and age-specific susceptibility to CrossFit-related injuries based on body parts and diagnoses. The presented information may be useful to develop a safer exercise program, especially for pediatric and adolescent CrossFit participants.

From barefoot hunter gathering to shod pavement pounding. Where to from here? A narrative review

Understanding the current prevalence and incidence of running injury from an evolutionary perspective has sparked great debate. Proponents of the evolutionary approach to understanding running injury suggest that humans ran using less injurious biomechanics prior to the invention of cushioned running shoes. Those who disagree with this view, point to the many runners, wearing cushioned running shoes, who do not get injured and suggest that the evolutionary approach is indulging in a 'natural fallacy'. This polarises the scientific debate into discrete categories such as 'shod' vs 'barefoot'. This review aims, first, to describe humans' innate impact moderating mechanisms which arise from our evolutionary legacy. Second, we discuss the impact of footwear on these mechanisms and the potential link to injury in some runners. Finally, we discuss the role of barefoot training in sports medicine and attempt to make some practical suggestions as to how it might be integrated in our modern urban environments.

Effect of neuromuscular training augmented with knee valgus control instructions on lower limb biomechanics of male runners

OBJECTIVE

To examine if combining neuromuscular training (NMT) with knee valgus control instructions (VCIs) can affect lower limb biomechanics and injury incidence in male novice runners and assess over 1-year follow-up.

DESIGN

Controlled laboratory Study.

SETTING

University research laboratory.

PARTICIPANTS

60 male novice runners randomly assigned into NMT (n = 20), NMT plus VCIs (n = 20), and sham (n = 20).

MAIN OUTCOME MEASURES

Kinematic and kinetic were measured at pre- and post-test and 1-year follow-up. Injury incidence assessed at pre-test and 1-year follow up.

RESULTS

There were significant between-group differences in kinetics after 6 weeks in NMT plus VCIs group. No significant differences were observed between NMT and NMT plus VCIs in kinematic variables. No significant change was seen in the sham in all variables. At 1-year follow-up, the minimal changes were seen in kinetic variables. Reduction reported running-related injuries were 31.58% in the NMT alone group, 65.52% in NMT plus VCIs group. In sham, it increased to 13.46%.

CONCLUSIONS

NMT plus VCIs was effective to reduce kinetics and improve kinematics in novice runners. Also, it could reduce injury incidence. This protocol may be an option for both athletic trainers and coaches for preventing of lower limbs' injury in male runners.

Real-time biofeedback integrated into neuromuscular training reduces high-risk knee biomechanics and increases functional brain connectivity: A preliminary longitudinal investigation

Prospective evidence indicates that functional biomechanics and brain connectivity may predispose an athlete to an anterior cruciate ligament injury, revealing novel neural linkages for targeted neuromuscular training interventions. The purpose of this study was to determine the efficacy of a real-time biofeedback system for altering knee biomechanics and brain functional connectivity. Seventeen healthy, young, physically active female athletes completed 6 weeks of augmented neuromuscular training (aNMT) utilizing real-time, interactive visual biofeedback and 13 served as untrained controls. A drop vertical jump and resting state functional magnetic resonance imaging were separately completed at pre- and posttest time points to assess sensorimotor adaptation. The aNMT group had a significant reduction in peak knee abduction moment (pKAM) compared to controls (p = .03, d = 0.71). The aNMT group also exhibited a significant increase in functional connectivity between the right supplementary motor area and the left thalamus (p = .0473 after false discovery rate correction). Greater percent change in pKAM was also related to increased connectivity between the right cerebellum and right thalamus for the aNMT group (p = .0292 after false discovery rate correction, r²  = .62). No significant changes were observed for the controls (ps > .05). Our data provide preliminary evidence of potential neural mechanisms for aNMT-induced motor adaptations that reduce injury risk. Future research is warranted to understand the role of neuromuscular training alone and how each component of aNMT influences biomechanics and functional connectivity.

Risk Factors for Lower-Extremity Injuries Among Contemporary Dance Students

OBJECTIVE

To determine whether student characteristics, lower-extremity kinematics, and strength are risk factors for sustaining lower-extremity injuries in preprofessional contemporary dancers.

DESIGN

Prospective cohort study.

SETTING

Codarts University of the Arts.

PATIENTS

Forty-five first-year students of Bachelor Dance and Bachelor Dance Teacher.

ASSESSMENT OF RISK FACTORS

At the beginning of the academic year, the injury history (only lower-extremity) and student characteristics (age, sex, educational program) were assessed using a questionnaire. Besides, lower-extremity kinematics [single-leg squat (SLS)], strength (countermovement jump) and height and weight (body mass index) were measured during a physical performance test.

MAIN OUTCOME MEASURES

Substantial lower-extremity injuries during the academic year were defined as any problems leading to moderate or severe reductions in training volume or in performance, or complete inability to participate in dance at least once during follow-up as measured with the Oslo Sports Trauma Research Center (OSTRC) Questionnaire on Health Problems. Injuries were recorded on a monthly basis using a questionnaire. Analyses on leg-level were performed using generalized estimating equations to test the associations between substantial lower-extremity injuries and potential risk factors.

RESULTS

The 1-year incidence of lower-extremity injuries was 82.2%. Of these, 51.4% was a substantial lower-extremity injury. Multivariate analyses identified that ankle dorsiflexion during the SLS (OR 1.25; 95% confidence interval, 1.03-1.52) was a risk factor for a substantial lower-extremity injury.

CONCLUSIONS

The findings indicate that contemporary dance students are at high risk for lower-extremity injuries. Therefore, the identified risk factor (ankle dorsiflexion) should be considered for prevention purposes.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of anterior cruciate ligament injury - Secondary publication

BACKGROUND

This clinical guideline presents recommendations for the management of patients with anterior cruciate ligament (ACL) injury, endorsed by the Japanese Orthopaedic Association (JOA) and Japanese Orthopaedic Society of Knee, Arthroscopy and Sports Medicine (JOSKAS).

METHODS

The JOA ACL guideline committee revised the previous guideline based on "Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014", which proposed a desirable method for preparing clinical guidelines in Japan. Furthermore, the importance of "the balance of benefit and harm" was also emphasized. This guideline consists of 21 clinical questions (CQ) and 23 background questions (BQ). For each CQ, outcomes from the literature were collected and evaluated systematically according to the adopted study design.

RESULTS

We evaluated the objectives and results of each study in order to make a decision on the level of evidence so as to integrate the results with our recommendations for each CQ. For BQ, the guideline committee proposed recommendations based on the literature.

CONCLUSIONS

This guideline is intended to be used by physicians, orthopedic surgeons, physical therapists, and athletic trainers managing ACL injuries. We hope that this guideline is useful for appropriate decision-making and improved management of ACL injuries.

Running-related muscle activation patterns and tibial acceleration across puberty

This study examined whether differences exist in tibial acceleration transients and electromyography (EMG) variables during running across female pubertal development. Sixty-four girls classified as pre- (n = 19), early/mid- (n = 22) and late/post-pubertal development (n = 23) ran in a laboratory whilst EMG data were recorded from quadriceps, hamstring and calf muscle groups, and acceleration transients from a triaxial accelerometer. The late/post-pubertal girls exhibited delayed vastus lateralis onset (mean difference (MD) = 0.02, 95% CI = 0.008, 0.34 ms)) compared to pre-pubertal girls, lower vastus lateralis pre-activation (MD = 7.02, 95% CI = 12.63, 1.42%) compared to early/mid-pubertal girls, and longer time to peak (TTP) anterior/posterior (A/P) tibial acceleration compared to pre-pubertal girls (MD = 0.02, 95% CI = 0.006, 0.03 s). By contrast, late/post-pubertal girls demonstrated earlier semitendinosus onset compared to both early/mid- (MD = 0.02, 95% CI = 0.03, 0.005 ms) and pre-pubertal girls (MD = 0.02, 95% CI = 0.04, 0.007 ms). No other between-group differences were found for peak A/P, vertical and TTP vertical tibial acceleration (p > 0.05). Subsequently, regression analysis revealed that EMG variables accounted for approximately 34% (R² = 0.34) of the variance in TTP A/P tibial acceleration. These findings highlight that neuromuscular recruitment patterns and kinetics differ across female pubertal development while running and should be further explored in the context of adolescent female musculoskeletal injuries.

Variation in ACL and MCL Strain Before Initial Contact Is Dependent on Injury Risk Level During Simulated Landings

Background

The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC.

Purpose

To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC.

Study Design

Descriptive laboratory study.

Methods

A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors.

Results

Strain responses during simulated landing tasks for the ACL (P ≥ .545) and MCL (P ≥ .489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P < .001) and MCL (P < .001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC.

Conclusion

Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture.

Clinical Relevance

Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

Influence of relative injury risk profiles on anterior cruciate ligament and medial collateral ligament strain during simulated landing leading to a noncontact injury event

BACKGROUND

Athletes have traditionally been subdivided into risk classifications for ACL injury relative to the biomechanical traits they display during landing. This investigation aimed to discern whether these separate risk classifications elicit strain differences on the ACL and MCL during landing. It was hypothesized that the higher risk simulation profiles would exhibit greater ACL strain and that the ACL would exhibit greater strain than the MCL under all conditions.

METHOD

The mechanical impact simulator was used to simulate landing on a cohort of 46 cadaveric specimens. The simulator applied external joint loads to the knee prior to impulse delivery. These loads were organized into a series of profiles derived from in vivo motion capture previously performed on a cohort of 44 athletes and represented various risk classifications. Strain gauges were implanted on the ACL and MCL and simulations performed until a structural failure was elicited. Differences were assessed with Kruskal-Wallis tests.

FINDINGS

The highest-risk profiles tended to exhibit greater peak ACL strain and change in ACL strain than the baseline- and moderate-risk profiles. Specimens that failed during lower-risk simulations expressed greater strain at these loads than specimens that completed higher-risk simulations. The ACL recorded greater strain than the MCL throughout all simulation profiles.

INTERPRETATION

This behavior justifies why neuromuscular interventions have greater impact on higher-risk athletes and supports the continued screening and targeted training of those athletes that express greater injury risk. The loading disparity between ACL and MCL justifies their limited concomitant injury rate.