Athletic groin pain (part 2): a prospective cohort study on the biomechanical evaluation of change of direction identifies three clusters of movement patterns

Cleft Sign in MRI May Represent the Disruption of Cartilage Structure within Pubic Symphysis and Pubic Plate: A Cadaver Case Report

BACKGROUND/OBJECTIVES

Long-standing groin pain is a severe issue for athletes, often associated with the cleft sign on magnetic resonance imaging (MRI) scans, yet its underlying causes are poorly understood. The purpose of this study is to histologically examine the pubic plate structure in cadavers with and without the cleft sign on MRI, shedding light on the pathology behind the cleft sign.

METHODS

Three fresh human pelvic cadavers underwent 3.0T MRI to detect the cleft sign before histological dissection of pubic plates. Pubic plate tissues were fixed in formalin, decalcified, and processed. Of the two cleft sign-negative specimens, one was cut into sagittal sections, and the other was cut into coronal sections for histology. For the cleft sign positive specimen, a sagittal section was cut. Moreover, 5 µm thick sections were cut at different axial levels for each orientation. Sections were subjected to Safranin O, Alcian blue, and Herovici's staining or hematoxylin and eosin staining.

RESULTS

MRI confirmed that one specimen had a cleft sign in the inferior region on both sides of the pubis and that two specimens had no cleft sign. Both sagittal and coronal sections showed the presence of a cartilage structure continuing from the pubic symphysis to 3 mm laterally within the pubic plate. In the specimen with a positive cleft sign, cartilage damage within the pubic symphysis and pubic plate was identified as revealed by Safranin O staining, Herovici's staining, and H&E staining.

CONCLUSIONS

This study elucidated the existence of a cartilage component extending from the pubic symphysis to the pubic plate. The cleft sign in MRI correlated with a disruption in the cartilage component in histology within this specific area.

Evaluating Joint Angle Data for Clinical Assessment Using Multidimensional Inverse Kinematics with Average Segment Morphometry

Movement analysis is a critical tool in understanding and addressing various disabilities associated with movement deficits. By analyzing movement patterns, healthcare professionals can identify the root causes of these alterations, which is essential for preventing, diagnosing, and rehabilitating a broad spectrum of medical conditions, disabilities, and injuries. With the advent of affordable motion capture technologies, quantitative data on patient movement is more accessible to clinicians, enhancing the quality of care. Nonetheless, it is crucial that these technologies undergo rigorous validation to ensure their accuracy in collecting and monitoring patient movements, particularly for remote healthcare services where direct patient observation is not possible. In this study, motion capture technology was used to track upper extremity movements during a reaching task presented in virtual reality. Kinematic data was then calculated for each participant using a scaled dynamic inertial model. The goal was to evaluate the accuracy of joint angle calculations using inverse kinematics from motion capture relative to the typical movement redundancy. Shoulder, elbow, radioulnar, and wrist joint angles were calculated with models scaled using either direct measurements of each individual's arm segment lengths or those lengths were calculated from individual height using published average proportions. The errors in joint angle trajectories calculated using the two methods of model scaling were compared to the inter-trial variability of those trajectories. The variance of this error was primarily within the normal range of variability between repetitions of the same movements. This suggests that arm joint angles can be inferred with good enough accuracy from motion capture data and individual height to be useful for the clinical assessment of motor deficits.

Athletes With Adductor-Related Groin Pain: A Narrative Review

Adductor-related groin pain is extremely common among athletes, and despite its high prevalence and impact, there is no consensus regarding taxonomy, anatomy, physiopathology, or treatment. We performed a comprehensive literature review and tried to demystify this pathology and its treatment. The Doha agreement classification and its impact are scrutinized as well as the complexity of the proximal adductor longus (AL) insertion and its relationship with the pyramidalis-anterior pubic ligament-AL complex. The stress-shielding and compression theories for the origin of AL tendon pathology are exploited along with how this knowledge translates into injury prevention protocols and surgical techniques. The importance of active rehabilitation protocols and intersegmental control-focused programs is highlighted. The role of an enthesis injection in the treatment algorithm is discussed along with when to perform a tenotomy. The differences between selective and complete tenotomy are highlighted.

Manipulation of task constraints is the most effective motor learning method for reducing risk factors for ACL injury during side-step cutting in both male and female athletes

This study compared the efficacy of linear, non-linear and differential methods on variables related to ACL injury risk of a side-step cutting task in male and female basketball players. Thirty males and thirty females practiced basketball skills in sixty 90-minute sessions across 5 months. Ten players trained in each of the LP, NLP and DL female/male groups separately. Before and after the intervention, each player was tested on a side-step cutting task. A repeated 3 × 2 × 2 factorial ANOVA with repeated measures was performed for each biomechanical variable. Variables (trunk, hip, and knee flexion angle, knee valgus angle, ankle dorsiflexion angle, hip, knee, and ankle ROM, peak VGRF and knee extension/flexion, knee moment and ankle dorsiflexion moment) all revealed significant test by group interactions (P < 0.05) but no significant group by sex interactions (P > 0.05). In both sex, biomechanical changes were better in the NLP, followed by the DL and LP. It is argued that the advantage of the NLP method results from increased exploration of movement solutions induced by the manipulation of task constraints. Therefore, according to the NLP, it is possible to manipulate the constraints without feedback and the model/pattern can keep the athlete away from possible risks.

Running-Related Injury Incidence: Does It Correlate with Kinematic Sub-groups of Runners? A Scoping Review

BACKGROUND

Historically, kinematic measures have been compared across injured and non-injured groups of runners, failing to take into account variability in kinematic patterns that exist independent of injury, and resulting in false positives. Research led by gait patterns and not pre-defined injury status is called for, to better understand running-related injury (RRI) aetiology and within- and between-group variability.

OBJECTIVES

Synthesise evidence for the existence of distinct kinematic sub-groups across a population of injured and healthy runners and assess between-group variability in kinematics, demographics and injury incidence.

DATA SOURCES

Electronic database search: PubMed, Web of Science, Cochrane Central Register of Controlled Trials (Wiley), Embase, OVID, Scopus.

ELIGIBILITY CRITERIA

Original, peer-reviewed, research articles, published from database start to August 2022 and limited to English language were searched for quantitative and mixed-methods full-text studies that clustered injured runners according to kinematic variables.

RESULTS

Five studies (n = 690) were included in the review. All studies detected the presence of distinct kinematic sub-groups of runners through cluster analysis. Sub-groups were defined by multiple differences in hip, knee and foot kinematics. Sex, step rate and running speed also varied significantly between groups. Random injury dispersal across sub-groups suggests no strong evidence for an association between kinematic sub-groups and injury type or location.

CONCLUSION

Sub-groups containing homogeneous gait patterns exist across healthy and injured populations of runners. It is likely that a single injury may be represented by multiple movement patterns, and therefore kinematics may not predict injury risk. Research to better understand the underlying causes of kinematic variability, and their associations with RRI, is warranted.

Effectiveness of a Preventative Program for Groin Pain Syndrome in Elite Youth Soccer Players: A Prospective, Randomized, Controlled, Single-Blind Study

Groin pain syndrome (GPS) is a prevalent issue in soccer. This study assessed the effectiveness of a new preventive protocol on GPS for youth soccer players. The protocol included targeted stretching and strengthening exercises for the adductor and core muscles from preseason to midseason. A questionnaire and two pain provocation tests were used for the evaluation. Mild GPS required positive results in at least two evaluations, while severe GPS was associated with pain incompatible with engagement in any activity confirmed by diagnostic ultrasound. Forty-two elite male athletes (aged 16.9 ± 0.7 years) participated in the study, with half of them assigned to the usual training (control group) and the remaining athletes undergoing the preventive protocol (treatment group) for 24 weeks. GPS rates were 14.3% (three diagnoses: two mild, one severe) in the treatment group and 28.6% (six diagnoses: three mild, three severe) in the control group. Toward the end of the season, three players, one from the treatment group and two from the control group had to stop playing due to severe GPS problems. In addition, one player in the control group stopped midseason. Even though the reduction in the risk of developing GPS was not significant (relative risk of 0.50 ([95%CI 0.14 to 1.74], p = 0.2759), the halved incidence of severe GPS and the increased muscle strength related to the treatment (p = 0.0277) are encouraging data for future studies.

Estimation of horizontal running power using foot-worn inertial measurement units

Feedback of power during running is a promising tool for training and determining pacing strategies. However, current power estimation methods show low validity and are not customized for running on different slopes. To address this issue, we developed three machine-learning models to estimate peak horizontal power for level, uphill, and downhill running using gait spatiotemporal parameters, accelerometer, and gyroscope signals extracted from foot-worn IMUs. The prediction was compared to reference horizontal power obtained during running on a treadmill with an embedded force plate. For each model, we trained an elastic net and a neural network and validated it with a dataset of 34 active adults across a range of speeds and slopes. For the uphill and level running, the concentric phase of the gait cycle was considered, and the neural network model led to the lowest error (median ± interquartile range) of 1.7% ± 12.5% and 3.2% ± 13.4%, respectively. The eccentric phase was considered relevant for downhill running, wherein the elastic net model provided the lowest error of 1.8% ± 14.1%. Results showed a similar performance across a range of different speed/slope running conditions. The findings highlighted the potential of using interpretable biomechanical features in machine learning models for the estimating horizontal power. The simplicity of the models makes them suitable for implementation on embedded systems with limited processing and energy storage capacity. The proposed method meets the requirements for applications needing accurate near real-time feedback and complements existing gait analysis algorithms based on foot-worn IMUs.

Aetiological Factors of Running-Related Injuries: A 12 Month Prospective "Running Injury Surveillance Centre" (RISC) Study

BACKGROUND

Running-related injuries (RRIs) are a prevalent issue for runners, with several factors proposed to be causative. The majority of studies to date are limited by retrospective study design, small sample sizes and seem to focus on individual risk factors in isolation. This study aims to investigate the multifactorial contribution of risk factors to prospective RRIs.

METHODS

Recreational runners (n = 258) participated in the study, where injury history and training practices, impact acceleration, and running kinematics were assessed at a baseline testing session. Prospective injuries were tracked for one year. Univariate and multivariate Cox regression was performed in the analysis.

RESULTS

A total of 51% of runners sustained a prospective injury, with the calf most commonly affected. Univariate analysis found previous history of injury < 1 year ago, training for a marathon, frequent changing of shoes (every 0-3 months), and running technique (non-rearfoot strike pattern, less knee valgus, greater knee rotation) to be significantly associated with injury. The multivariate analysis revealed previous injury, training for a marathon, less knee valgus, and greater thorax drop to the contralateral side to be risk factors for injury.

CONCLUSION

This study found several factors to be potentially causative of injury. With the omission of previous injury history, the risk factors (footwear, marathon training and running kinematics) identified in this study may be easily modifiable, and therefore could inform injury prevention strategies. This is the first study to find foot strike pattern and trunk kinematics to relate to prospective injury.

Training for "Worst-Case" Scenarios in Sidestepping: Unifying Strength and Conditioning and Perception-Action Approaches

Sidesteps can impose high demands on the knee joint and lead to non-contact anterior cruciate ligament (ACL) injuries. Understanding how different constraints shape an athlete's movement strategy and the associated joint demands can help design training interventions to increase injury resilience. Motor capacities, such as muscular strength and power, act as boundaries for the safe execution of perceptual-motor skills and co-determine the emergence of unique movement strategies. Increasing single- and multi-joint strength enables a broader solution space for movement strategies and increases load tolerance. Manipulating task constraints during sidesteps can be used in the training process to systematically expose athletes to increasing demands (on the knee joint or any joint or structure) in preparation for "worst-case" scenarios. In particular, the type and timing of information available influence the preparation time, subsequently affecting the movement strategy and the associated magnitude of external knee joint loading (e.g., knee valgus moment). While an athlete's perceptual-cognitive skills contribute to the preparation time during in situ scenarios, attempts to further improve those skills with the aim of increasing athlete preparation time prior to "worst-case" scenarios are yet to demonstrate conclusive evidence of transfer to on-field situations. Therefore, in the current article, we reflect on the impact of different interacting constraints that influence the execution of sidesteps during in situ scenarios and impose high demands on the knee joint. Subsequently, we discuss how an integrated perspective, drawing on knowledge and perspectives from strength and conditioning and perception-action, may enhance an athlete's ability to withstand "worst-case" scenarios and adapt to perform varied movement executions when sidestepping.

Injury-Inciting Activities in Male and Female Football Players: A Systematic Review

BACKGROUND

A comprehensive examination of the sport-specific activities performed around the time of injury is important to hypothesise injury mechanisms, develop prevention strategies, improve management, and inform future investigations. The aim of this systematic review is to summarise the current literature describing the activities performed around the time of injury in football (soccer).

METHODS

A systematic search was carried out in PubMed, Web of Science, SPORTDiscus, and OpenGrey. Studies were included if participants were football players aged > 13 years old and the activities performed at the time of injury were reported together with the total number of injuries. Risk of bias was assessed using an adapted version of checklists developed for prevalence studies. The activities reported by the studies were grouped to account for inconsistent reporting, and the proportion of each injury activity was calculated. Data were not meta-analysed due to high heterogeneity of methods and classification criteria.

RESULTS

We included 64 studies reporting on 56,740 injuries in total. ACL injures were analysed by 12 studies, ankle/foot and knee injuries were analysed by five studies, thigh injuries were analysed by four studies, hip/groin injuries were analysed by three studies, and hamstring injuries were analysed by two studies. Five studies analysed more than one type of injury and 38 studies did not specify the type of injuries analysed. Running and kicking were the predominant activities leading to thigh and hamstring injuries. Changing direction and kicking were the predominant activities leading to hip and groin injuries and duels were the predominant activities leading to ankle injuries. Duels and pressing seem the predominant activities leading to ACL injuries, while results for other knee and general injuries were inconsistent.

CONCLUSIONS

A qualitative summary of the activities performed at the time of injury has been reported. The results need to be interpreted carefully due to the risk of bias observed in the included studies. If we are to meaningfully progress our knowledge in this area, it is paramount that future research uses consistent methods to record and classify injuries and activities leading up to and performed at the time of injury.

REGISTRATION

The protocol of this systematic review was registered at the Open Science Framework ( https://doi.org/10.17605/OSF.IO/U96KV ).

Effects of the menstrual cycle phase on anterior cruciate ligament neuromuscular and biomechanical injury risk surrogates in eumenorrheic and naturally menstruating women: A systematic review

BACKGROUND

Eumenorrheic women experience cyclic variations in sex hormones attributed to the menstrual cycle (MC) which can impact anterior cruciate ligament (ACL) properties, knee laxity, and neuromuscular function. This systematic review aimed to examine the effects of the MC on ACL neuromuscular and biomechanical injury risk surrogates during dynamic tasks, to establish whether a particular MC phase predisposes women to greater ACL injury risk.

METHODS

PubMed, Medline, SPORTDiscus, and Web of Science were searched (May-July 2021) for studies that investigated the effects of the MC on ACL neuromuscular and biomechanical injury risk surrogates. Inclusion criteria were: 1) injury-free women (18-40 years); 2) verified MC phases via biochemical analysis and/or ovulation kits; 3) examined neuromuscular and/or biomechanical injury risk surrogates during dynamic tasks; 4) compared ≥1 outcome measure across ≥2 defined MC phases.

RESULTS

Seven of 418 articles were included. Four studies reported no significant differences in ACL injury risk surrogates between MC phases. Two studies showed evidence the mid-luteal phase may predispose women to greater risk of non-contact ACL injury. Three studies reported knee laxity fluctuated across the MC; two of which demonstrated MC attributed changes in knee laxity were associated with changes in knee joint loading (KJL). Study quality (Modified Downs and Black Checklist score: 7-9) and quality of evidence were low to very low (Grading of Recommendations Assessment Development and Evaluation: very low).

CONCLUSION

It is inconclusive whether a particular MC phase predisposes women to greater non-contact ACL injury risk based on neuromuscular and biomechanical surrogates. Practitioners should be cautious manipulating their physical preparation, injury mitigation, and screening practises based on current evidence. Although variable (i.e., magnitude and direction), MC attributed changes in knee laxity were associated with changes in potentially hazardous KJLs. Monitoring knee laxity could therefore be a viable strategy to infer possible ACL injury risk.

Return to Play in Long-Standing Adductor-Related Groin Pain: A Delphi Study Among Experts

Background

Groin pain is a very common injury in multidirectional sports such as soccer, ice hockey, rugby and Australian football. Long-standing adductor-related groin pain is a persistent clinical condition and a frequent complaint in athletes involved in sports that require multiplanar movement patterns (change of direction, high-speed sprinting and kicking). To date, the lack of rehabilitation guidelines and return-to-play criteria makes this clinical entity difficult to manage. The aim of the present Delphi was to suggest, based on opinion and practical experience of a panel of experts, potential criteria that could be taken into consideration by clinicians in the RTP decision-making process in athletes suffering from long-standing adductor-related groin pain.

Methods

Thirty two out of 40 experts participated to a 3-Round Delphi questionnaire. In round 1, open-ended and closed questions about 9 different sections (palpation, flexibility, strength, patient-reported outcome measures, imaging, intersegmental control, performance tests, sport-specific skills, training load) were proposed to investigate return to play evaluation criteria used by each expert. Responses were analysed and coded to produce round 2 questionnaire that investigated only the sections and the items that reached the cut-off value (≥ 70%). Round 3 questionnaire was based on sections and items that reached cut-off value in previous rounds and experts rated their agreement for return to play criteria with a 5-point Likert Scale. Descriptive statistics enabled interpretation of consensus.

Results

High participation rate (80%) and response rate across the 3 rounds (100%) were recorded. 6 sections reached positive consensus in round 1, 1 section reached negative consensus. In round 2 positive consensus was confirmed only for 3 sections and negative consensus for 1 section. In round 3, positive agreement was established for strength (3 items), performance tests (3 items) and sport-specific skills (2 items) sections. Negative consensus was confirmed for imaging section.

Conclusion

Experts agreed that strength, performance tests and sport-specific skills can be used to support RTP decision, while imaging cannot be used. These findings could be useful in assisting clinicians in the RTP decision making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-021-00400-z.

Movement Variability and Loading Characteristics in Athletes With Athletic Groin Pain: Changes After Successful Return to Play and Compared With Uninjured Athletes

Background:

Athletic groin pain (AGP) can lead to altered movement patterns during rapid deceleration and acceleration. However, the effect of AGP on movement variability and loading patterns during such actions remains less clear.

Purpose:

To investigate, using a continuous lateral hurdle hop task, how movement variability and magnitude measures of 3-dimensional (3D) kinematic, kinetic, and vertical ground-reaction force (vGRF) variables are (1) affected by AGP (AGP vs uninjured controls [CON]) and (2) changed after successful rehabilitation (AGP prerehabilitation vs AGP postrehabilitation vs CON).

Study Design:

Controlled laboratory study.

Methods:

A total of 36 athletes diagnosed with AGP and 36 uninjured CON athletes matched on age (18-35 years), level (subelite), and type of sports played (multidirectional field sport) performed a continuous lateral hurdle hop test that involved 10 side-to-side hops over a 15-cm hurdle. The 3D joint kinematic, kinetic, and vGRF variables (total, eccentric, and concentric; ground contact time, peak force, and impulse; and eccentric rate of force development) were examined. The AGP and CON groups were tested at baseline, and the AGP group was retested after participants successfully completed a standardized, exercise-based rehabilitation program targeting intersegmental control.

Results:

There were no differences in baseline characteristics between the AGP (mean ± SD: age, 27.5 ± 4.8 years; height, 179.8 ± 6.3 cm; mass, 80.3 ± 7.1 kg) and CON (mean ± SD: age, 24.1 ± 4.5 years; height, 181.0 ± 5.8 cm; mass, 80.4 ± 8.2 kg) groups. At baseline, athletes with AGP demonstrated altered loading patterns in the vGRF (longer ground contact times, reduced peak force, and reduced rate of force development) compared with CON athletes, while no significant difference in any movement variability variables was evident. After rehabilitation, the athletes with AGP demonstrated significant changes in transverse and coronal plane hip and trunk kinematics, with no significant differences in vGRF variables compared with the CON group.

Conclusion:

The differences in baseline vGRF measures between the AGP and CON groups were no longer evident after athletes with AGP underwent rehabilitation. No differences in movement variability were evident between the AGP and CON groups, either before or after rehabilitation.

Clinical Relevance:

Rehabilitation programs should consider targeting intersegmental hip and trunk movement patterns to positively influence loading patterns in athletes with AGP.

Are sprint accelerations related to groin injuries? A biomechanical analysis of adolescent soccer players

Groin injuries have one of the highest incidences in soccer and can be career threatening, especially for adolescents, due to their high recurrence rate. Quick accelerations have been connected to groin injuries along with kicking and change of directions. Purpose of this study was to examine the hip joint kinematics, kinetics and the muscle forces of adductor longus and gracilis during first ground contact of a linear sprint acceleration performed by adolescent soccer players. Twenty-two male participants were investigated with 3D motion capture and two force plates. Inverse dynamics were used to calculate the kinematics, kinetics and muscle forces. The kinematics show a constant extension during the stance phase and a quick transition from an abduction to an adduction movement at 90% stance, which coincides with the highest forces in adductor longus and gracilis. This indicates a high load on the adductor muscles due to eccentric contractions combined with high muscle forces in the adductors. Compared to previously investigated inside passing and change of direction movements, adductor muscle forces and angular velocities are higher in this study. Therefore, it is suggested that sprint accelerations are likely to be connected to the development of groin injuries in adolescent soccer players.

Frontal plane lower extremity alignment in adolescent athletes with chronic hip adductor-related groin injury symptoms: A case-control study

OBJECTIVE

To compare trunk and lower extremity frontal plane projection angles (FPPA) during single leg squat (SLS) performance, perceived hip and groin function and symptoms, and isometric hip strength of adolescent athletes with chronic hip adductor-related groin injury (HARGI) symptoms and age, gender, and sport-matched healthy subjects.

DESIGN

Case-control study.

SETTING

Junior Olympic Development Training Centre.

PARTICIPANTS

Twenty-six athletes at 59.1 ± 60 weeks (range = 12-208 weeks) post-index grade II HARGI injury who had continued sport training (injury group) and 26 control group subjects.

MAIN OUTCOME MEASURES

SLS trunk, hip, and knee FPPA, isometric hip strength standardized to bodyweight, and Copenhagen Hip and Groin Outcome Scores (HAGOS).

RESULTS

The injury group had greater bilateral knee FPPA, and greater injury side hip FPPA during maximum SLS. Injury group HAGOS subscale scores were lower than control group scores. Hip abductor, adductor, external rotator, and internal rotator strength was lower at the injury side of the injury group compared to the matched control group limb. Forward stepwise multiple regression analysis of the injury group found that 50% of injury side knee FPPA was predicted by hip internal rotator strength and time post-index HARGI; and 47% of injury side hip FPPA was predicted by other side hip flexor strength and the HAGOS function, sport and recreation subscale score (p = 0.002).

CONCLUSIONS

Greater injury side hip and bilateral knee FPPA during maximum SLS, lower self-reported hip symptom and function scores, and less injury side hip abductor, adductor, external rotator and internal rotator strength suggests that adolescent athletes with chronic HARGI symptoms are at an increased risk for sustaining a non-contact knee injury. Impaired hip internal rotator strength at the side of the chronic HARGI was related to increased knee FPPA, and impaired hip flexor strength at the other side of the HARGI was related to increased hip FPPA. Findings support using SLS performance testing in this athlete group to help determine safe return to sport training readiness.

Applications and limitations of current markerless motion capture methods for clinical gait biomechanics

BACKGROUND

Markerless motion capture has the potential to perform movement analysis with reduced data collection and processing time compared to marker-based methods. This technology is now starting to be applied for clinical and rehabilitation applications and therefore it is crucial that users of these systems understand both their potential and limitations. This literature review aims to provide a comprehensive overview of the current state of markerless motion capture for both single camera and multi-camera systems. Additionally, this review explores how practical applications of markerless technology are being used in clinical and rehabilitation settings, and examines the future challenges and directions markerless research must explore to facilitate full integration of this technology within clinical biomechanics.

METHODOLOGY

A scoping review is needed to examine this emerging broad body of literature and determine where gaps in knowledge exist, this is key to developing motion capture methods that are cost effective and practically relevant to clinicians, coaches and researchers around the world. Literature searches were performed to examine studies that report accuracy of markerless motion capture methods, explore current practical applications of markerless motion capture methods in clinical biomechanics and identify gaps in our knowledge that are relevant to future developments in this area.

RESULTS

Markerless methods increase motion capture data versatility, enabling datasets to be re-analyzed using updated pose estimation algorithms and may even provide clinicians with the capability to collect data while patients are wearing normal clothing. While markerless temporospatial measures generally appear to be equivalent to marker-based motion capture, joint center locations and joint angles are not yet sufficiently accurate for clinical applications. Pose estimation algorithms are approaching similar error rates of marker-based motion capture, however, without comparison to a gold standard, such as bi-planar videoradiography, the true accuracy of markerless systems remains unknown.

CONCLUSIONS

Current open-source pose estimation algorithms were never designed for biomechanical applications, therefore, datasets on which they have been trained are inconsistently and inaccurately labelled. Improvements to labelling of open-source training data, as well as assessment of markerless accuracy against gold standard methods will be vital next steps in the development of this technology.

Impact of prior anterior cruciate ligament, hamstring or groin injury on lower limb strength and jump kinetics in elite female footballers

OBJECTIVE

To compare lower limb strength and countermovement jump (CMJ) kinetics between elite female footballers with and without a history of anterior cruciate ligament reconstruction (ACLR), hamstring strain, or hip/groin injury.

DESIGN

Cross-sectional.

SETTING

Field-based.

PARTICIPANTS

369 elite female Australian football, soccer and rugby league players aged 15-35.

MAIN OUTCOME MEASURES

Isometric hip adductor and abductor strength, eccentric knee flexor strength, and CMJ vertical ground reaction forces, including between-leg asymmetry. Players reported their lifetime history of ACLR, and whether they had sustained a hamstring strain, or hip/groin injury in the previous 12-months.

RESULTS

Players with a unilateral history of ACLR (n = 24) had significant between-leg asymmetry in eccentric knee flexor strength (mean = -6.3%, 95%CI = -8.7 to -3.9%, P < .001), isometric hip abductor strength (mean = -2.5%, 95%CI = -4.3 to -0.7%, P = .008), and CMJ peak landing force (mean = -5.5%, 95%CI = -10.9 to -0.1%, P = .046). Together, between-leg asymmetry in eccentric knee flexor strength, isometric hip abductor strength, and CMJ peak landing force distinguished between players with and without prior ACLR with 93% accuracy.

CONCLUSION

Elite female footballers with a history of ACLR, but not hamstring or hip/groin injury, exhibit persistent between-leg asymmetries in lower limb strength and jump kinetics following a return to sport.

Running biomechanics in football players with and without hip and groin pain. A cross-sectional analysis of 116 sub-elite players

OBJECTIVE

Examine whether football players with hip and/or groin (hip/groin) pain have impaired running biomechanics when compared to pain-free players, analysing men and women independently.

DESIGN

Cross-sectional.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Seventy-eight (62 men, 16 women) football players with >6months of hip/groin pain and a positive flexion-adduction-internal rotation test and 38 (25 men, 13 women) asymptomatic players.

MAIN OUTCOME MEASURES

Pelvis angles and hip, knee, and ankle joint angles and moments were analysed during the stance phase of overground running at 3-3.5 m⋅s^-1. Continuous joint angle and moment data were compared between symptomatic and asymptomatic football players of the same sex using statistical parametric mapping. Joint moment impulses (area under the curve) were compared between groups using linear regression models.

RESULTS

Symptomatic football players did not display significant differences in pelvis angles or lower-limb joint angles, moments, or moment impulses during the stance phase of running, when compared to asymptomatic players of the same sex.

CONCLUSION

Our large sample of football players with hip/groin pain who were still participating in competitive sport displayed similar running biomechanics to asymptomatic players. Impaired running biomechanics might exist in people with worse hip/groin pain, warranting future investigation.

Kinematics observed during ACL injury are associated with large early peak knee abduction moments during a change of direction task in healthy adolescents

Cluster analysis of knee abduction moment waveforms may be useful to examine biomechanical data. The aim of this study was to analyze if the knee abduction moment waveform of early peaks, consistent with anterior cruciate ligament injury mechanisms, was associated with foot-trunk distance, knee kinematics, and heel strike landing posture, all of which have been observed during anterior cruciate ligament injuries. One hundred and seventy-seven adolescent athletes performed cutting maneuvers, marker-based motion capture collected kinetic and marker data and an 8-segment musculoskeletal model was constructed. Knee abduction moment waveforms were clustered as either a large early peak, or not a large early peak using a two-step process with Euclidean distances and the Ward-d2 cluster method. Mediolateral distance between foot and trunk was associated with the large early peak waveform with an odds ratio (95% confidence interval) of 3.4 (2.7-4.4). Knee flexion angle at initial contact and knee flexion excursion had odds ratios of 1.9 (1.6-2.4) and 1.6 (1.3-2.0). Knee abduction excursions had an odds ratio of 1.8 (1.1-2.4) and 1.8 (1.4-2.4), respectively. Heel strike landings and anteroposterior distance between foot and trunk were not associated with the large early peak waveform with odds ratios of 1.2 (0.9-1.7) and 1.1 (0.8-1.3), respectively. The knee abduction moment waveform is associated with several kinematic variables observed during ACL injury. The results support intervention programs that can modify these kinematics and thus reduce early stance phase knee abduction moments.

Hip Muscle Strength Explains Only 11% of the Improvement in HAGOS With an Intersegmental Approach to Successful Rehabilitation of Athletic Groin Pain

BACKGROUND

Exercise-based rehabilitation targeting intersegmental control has high success rates and fast recovery times in the management of athletic groin pain (AGP). The influence of this approach on hip strength and lower limb reactive strength and how these measures compare with uninjured athletes (CON) remain unknown. Additionally, the efficacy of this program after return to play (RTP) has not been examined.

PURPOSE

First, to examine differences in isometric hip strength, reactive strength, and the Hip and Groin Outcome Score (HAGOS) between the AGP and CON cohorts and after rehabilitation; second, to examine the relationship between the change in HAGOS and the change in strength variables after rehabilitation; last, to track HAGOS for 6 months after RTP.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 42 athletes diagnosed with AGP and 36 matched controls completed baseline testing: isometric hip strength, lower limb reactive strength, and HAGOS. After rehabilitation, athletes with AGP were retested, and HAGOS was collected at 3 and 6 months after RTP.

RESULTS

In total, 36 athletes with AGP completed the program with an RTP time of 9.8 ± 3.0 weeks (mean ± SD). At baseline, these athletes had significantly lower isometric hip strength (abduction, adduction, flexion, extension, external rotation: d = -0.67 to -1.20), single-leg reactive strength (d = -0.73), and HAGOS (r = -0.74 to -0.89) as compared with the CON cohort. Hip strength (d = -0.83 to -1.15) and reactive strength (d = -0.30) improved with rehabilitation and were no longer significantly different between groups at RTP. HAGOS improvements were maintained or improved in athletes with AGP up to 6 months after RTP, although some subscales remained significantly lower than the CON group (r = -0.35 to -0.51). Two linear regression features (hip abduction and external rotation) explained 11% of the variance in the HAGOS Sports and Recreation subscale.

CONCLUSION

Athletes with AGP demonstrated isometric hip strength and reactive strength deficits that resolved after an intersegmental control rehabilitation program; however, improved hip strength explained only 11% of improvement in the Sports and Recreation subscale. HAGOS improvements after pain-free RTP were maintained at 6 months.

Motor learning methods that induce high practice variability reduce kinematic and kinetic risk factors of non-contact ACL injury

The prevention of non-contact anterior cruciate ligament (ACL) injuries often involves movement training, but the effectiveness of different motor learning methods has not been fully investigated. The purpose of this study was therefore to examine the effects of linear pedagogy (LP), nonlinear pedagogy (NLP) and differential learning (DL) motor learning methods on changing kinetic and kinematic factors during expected sidestep cutting related to non-contact ACL injuries. These methods primarily differ in the amount and type of movement variability they induce during practice. Sixty-six beginner male soccer players (27.5 ± 2.7 years, 180.6 ± 4.9 cm, 78.2 ± 4.6 kg) were randomly allocated to a group that trained for 12 weeks with either a LP, NLP or DL type of motor learning methods. All participants completed a biomechanical evaluation of side-step cutting before and after the training period. Analysis of covariance was used to compare post-testing outcomes among the groups while accounting for group differences in baseline performance. Changes in all kinematic and kinetic variables in NLP and DL groups were significantly higher compared to the LP group. Most comparisons were also different between NLP and DL group with the exception of vertical ground reaction force, the knee extension/flexion, knee valgus, and ankle dorsiflexion moments. Our findings indicate that beginner male soccer players may benefit from training programs incorporating NLP or DL versus LP to lower biomechanical factors associated with non-contact ACL injury, most likely because of the associated increased execution variability during training. We discuss that practitioners should consider using the NLP or DL methods, and particular the NLP, during which variability is induced to guide search, when implementing training programs to prevent ACL injuries in soccer.

Muscle activity of cutting manoeuvres and soccer inside passing suggests an increased groin injury risk during these movements

Cutting manoeuvres and inside passing are thought to increase the risk of sustaining groin injuries. But both movements have received little research attention in this regard. The purpose of this study was to investigate the muscle activity of adductor longus and gracilis as well as hip and knee joint kinematics during \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$90^{\circ }$$\end{document}90∘-cutting and inside passing. Thirteen male soccer players were investigated with 3D-motion capturing and surface electromyography of adductor longus and gracilis while performing the two movements. Hip and knee joint kinematics were calculated with AnyBody Modelling System. Muscle activity of both muscles was significantly higher during the cutting manoeuvre compared to inside passing. Kinematics showed that the highest activity occurred during phases of fast muscle lengthening and eccentric contraction of the adductors which is known to increase the groin injury risk. Of both movements, cutting showed the higher activity and is therefore more likely to cause groin injuries. However, passing might also increase the risk for groin injuries as it is one of the most performed actions in soccer, and therefore most likely causes groin injuries through overuse. Practitioners need to be aware of these risks and should prepare players accordingly through strength and flexibility training.

Hip and Groin Injury Prevention in Elite Athletes and Team Sport - Current Challenges and Opportunities

Hip and groin injury (HAGI) has been reported as a source of significant time loss in elite sport. Field and court-based sports such as basketball, football, hockey, soccer, among others, require explosive multiplanar movement in single stance and high-speed change of direction. Often situations arise where sub-optimal pre-season training has occurred or congested in-season competition minimizes physiologic recovery periods between bouts of physical activity, both of which could magnify concomitant existing risk factors and increase injury risk. Identification and management of HAGI can be challenging as numerous structures within the region can be drivers of pain and injury, especially when considering the likelihood of concurrent pathology and injury reoccurrence. Focused prevention strategies have been suggested, but their practical clinical implementation has not been heavily investigated across the sporting spectrum. The purpose of this commentary is to review the historical and current state of HAGI, while focusing on applying evidence and clinical experience towards the development of future risk reduction strategies. Level of evidence: 5.

Lower-limb work during high- and low-impact activities in hip-related pain: Associations with sex and symptom severity

BACKGROUND

Hip-related pain (HRP) is described as a movement-related disorder. However, little attention is given to the way people with HRP move, especially in populations still participating in sport. Thus, limiting our understanding of movementbased impairments in HRP and their potential relationships with pain/symptoms.

RESEARCH QUESTION

(1) What are the differences in absolute and relative amounts of positive and negative lower-limb joint work during walking and the single-leg drop jump (SLDJ) in football players with and without HRP? (2) What are the relationships between lower-limb joint work and HRP burden?

METHODS

88 football players with HRP and 30 control football players were recruited. Positive and negative work done by the hip, knee, and ankle (and each joint's relative contribution to total work done) were calculated. The effect of sex on the relationship between HRP and work done, as well as the association between work done and International Hip Outcome Tool (iHOT33) scores, were assessed using linear and beta regressions models.

RESULTS

Walking: No joint work variables were significantly different between groups, nor were any relationships with iHOT33 scores evident. SLDJ: The knee's relative contribution to total lower-limb negative work done was 37.7 % and 42.4 % for women with and without HRP, respectively (P = 0.04). The iHOT33 was significantly associated with positive (P = 0.03 to <0.01) and negative (P = 0.02 to <0.01) work done by the hip as well as negative work done by the ankle (P = 0.03 to 0.01), independent of sex.

SIGNIFICANCE

Only one significant between-group comparison was revealed, involving the knee in female football players. In addition, football players with a greater selfreported burden of HRP tended to display lower hip joint work during the SLDJ. Rehabilitation programs could be targeted to address these impairments and normalize work done during high impact tasks in the management of HRP.

Rehabilitation interventions need more than methodological standardisation: an individualised approach

OBJECTIVES

The main aim in the current study was to use a single-subject analysis to profile the physical performance characteristics of individuals within an injured group and a between-group approach to profile the group as a whole. These profiles were then used to inform single-subject and between-group rehabilitation interventions.

METHODS

Fifty-three (28 with athletic groin pain and 25 non-injured) Gaelic football players (24.8 years±7.1 years; 179 cm±5.5 cm; 79.7 kg±9.2 kg) underwent 3D biomechanical analysis, which was used to measure a series of physical performance characteristics. The non-injured group was used to create a 'performance database' to compare the injured individuals, and a between-group analysis was also conducted. The scores from each analysis were used to inform the targets of interventions.

RESULTS

The analysis highlighted the variety of profiles that existed across the tested individuals and that these profiles differed from that of the between-group analysis. By analysing individuals in a single-subject approach, detail can be seen that is lost with between-group analysis.

Changes in the kinetics and kinematics of a reactive cut maneuver after successful athletic groin pain rehabilitation

Athletic groin pain (AGP) is a chronic, painful condition which is prevalent in players of field sports that require rapid changes of direction. Following successful rehabilitation, systematic changes have been observed in the kinetics and kinematics of pre-planned change of direction maneuvers, providing insight into potential foci for rehabilitation monitoring and for the assessment of interventions. However, changing direction in field sports is often reactive rather than pre-planned, and it is not known whether such post-rehabilitation changes are seen in reactive maneuvers. We analyzed the stance phase kinetics and kinematics of a 90° reactive cutting maneuver in 35 AGP patients before and after a successful exercise intervention program. Following the intervention, transverse plane rotation of the pelvis toward the intended direction of travel increased, and the body center of mass was positioned more anteriorly relative to the center of pressure. Ankle dorsiflexion also increased, and participants demonstrated greater ankle plantar flexor internal moment and power during the second half of stance. These findings provide insight into mechanical variables of potential importance in AGP, as identified during a maneuver based on a common sporting task.

Groin injury risk of pubertal soccer players increases during peak height velocity due to changes in movement techniques

Adolescent athletes experience an increase in injury incidence when they undergo peak height velocity (PHV). To find the reason behind this increase, the present study investigated if PHV influences hip joint kinematics, kinetics and adductor muscle forces in two groups of adolescent soccer players performing 90^°-cutting manoeuvres and inside passing. One group was estimated to be more than half a year before PHV (PRE, N = 12). The second group was estimated to be less than half a year before or after PHV (MID, N = 10). Maximum static gripping and adductor forces were measured. Motion capturing and inverse dynamics were used to calculate kinematics and kinetics. The MID group was significantly taller and heavier compared to PRE while the force measurements showed no differences. Statistics showed a higher hip abduction moment for MID during the cutting manoeuvre. Results from the anthropometrics and force measurements suggest that the moments of inertia of the participants' extremities increase faster than the muscles can adapt. A higher abduction moment of MID likely increases the load on the adductor muscles through a change of technique. Combining both findings, it is likely that the risk of suffering a groin injury is increased in the MID group.

Preseason Hip/Groin Strength and HAGOS Scores Are Associated With Subsequent Injury in Professional Male Soccer Players

DESIGN

Prospective cohort.

OBJECTIVE

To explore the association between preseason assessments of (1) isometric hip adductor and abductor strength using a novel field test and (2) the Copenhagen Hip and Groin Outcome Score (HAGOS) and subsequent hip/groin injury in male professional soccer players.

METHODS

In total, 204 male elite soccer players from 10 professional A-League and English Football League Championship clubs underwent assessments of hip adductor and abductor strength and completed the HAGOS in the 2017-2018 preseason. All subsequent hip/groin injuries were reported by team medical staff. Data reduction was conducted using principal-component analysis. The principal component for the HAGOS and 3 principal components for strength and imbalance measures were entered, with age and prior hip/groin injury, into a multivariable logistic regression model to determine their association with prospectively occurring hip/groin injury.

RESULTS

Twenty-four players suffered at least 1 hip/groin injury throughout the 2017-2018 season. The principal component for between-limb abduction imbalance (peak strength in the preferred kicking limb - nonpreferred limb) (odds ratio [OR] = 0.58; 95% confidence interval [CI]: 0.38, 0.90; P = .011), the principal component for peak adduction and abduction strength (OR = 0.71; 95% CI: 0.51, 1.00; P = .045), and the principal component for the HAGOS (OR = 0.77; 95% CI: 0.62, 0.96; P = .022) were independently associated with a reduced risk of future hip/groin injury. Receiver operating characteristic curve analysis of the whole model revealed an area under the curve of 0.76, which indicates a fair combined sensitivity and specificity of the included variables but an inability to correctly identify all subsequently injured players.

CONCLUSION

Hip abduction imbalance favoring the preferred kicking limb, higher levels of hip adductor and abductor strength, and superior HAGOS values were associated with a reduced likelihood of future hip/groin injury in male professional soccer players. J Orthop Sports Phys Ther 2020;50(5):234-242. Epub 17 Sep 2019. doi:10.2519/jospt.2020.9022.

Segmental coordination and variability of change in direction in long-standing groin pain

BACKGROUND

Long-standing groin pain (LSGP) is a chronic painful condition resulting in both impaired performance and time loss from participation in multidirectional field sport.

RESEARCH QUESTION

What are the differences in intersegmental coordination strategy and variability of trunk-pelvic and thigh coupling during change of direction in subjects with athletic LSGP and asymptomatic control subjects?

METHODS

A motion analysis system was used to collect 3-D kinematic data of the continuous relative phase and the variability of the right and left leg hip. Thoracic-thigh segment data were also collected during multiple ipsilateral turns at a self-selected pace from 16 males with LSGP and 16 asymptomatic controls. It is worth mentioning that, for a more detailed analysis, we divided each cycle diagram into four phases. Independent T-tests were used to compare the two groups.

RESULTS

Subjects with LSGP demonstrate except in phase 2 of the left foot, more out-of-phase movement with both increased variabilities in right/ left thigh - pelvic coupling, right/ left thigh-thoracic, and pelvic- thoracic in every 4 phases and in the decoupling of segmental coordination.

SIGNIFICANCE

Decrease in coordination with higher variability is apparent in subjects with LSGP and this aberrant coordination may lead to unexpected compensatory strategies and control impairments.

The sensitivity of joint kinematics and kinetics to marker placement during a change of direction task

The conventional gait model (CGM) refers to several closely related biomechanical models used in the objective analysis of human motion. Their use has become popular in the analysis of change of direction tasks to inform best practice in the prevention and rehabilitation of anterior cruciate ligament injury. As externally-placed markers define segment axes origins and orientations, kinematic and kinetic outputs from the CGM are sensitive to marker placement. The aim of this investigation was to quantify the sensitivity of lower extremity kinematics and knee moments to systematic differences in marker placement across the stance phase of a change of direction task. Systematic anterior/posterior displacements were applied to the lateral thigh, femoral epicondyle and tibia markers in software. One-dimensional statistical parametric mapping was used to determine the effect of marker placement across the entire stance phase of a 90° change of direction task. Marker placement error within previously reported inter-tester variability ranges caused significant differences in knee abduction moment, hip rotation angle, knee rotation angle, ankle abduction and rotation angle across various periods of stance. Discrete measures of these variables have been associated with increased frontal plane knee loading during change of direction, considered a key mechanism of anterior cruciate ligament injury. Systematic differences in marker placement may lead to incorrect group statistical inferences in such discrete measures.

Athletic groin pain patients and healthy athletes demonstrate consistency in their movement strategy selection when performing multiple repetitions of a change of direction test

OBJECTIVES

To report the consistency in movement strategy selection in athletic groin pain patients and to assess whether there are differences in consistency between athletic groin pain patients and healthy athletes.

DESIGN

Cross sectional exploratory study.

METHODS

Twenty athletic groin pain patients and 21 healthy athletes performed 15 repetitions of 110° change of direction task. Lower limb and trunk kinematics alongside ground reaction forces were collected. A correlation-to-mean algorithm was used to allocate each trial to a movement strategy using kinematic and kinetic features. Mann-Whitney U tests were used to compare the frequency of the most selected strategy (i.e. consistency) and fuzziness between athletic groin pain patients and healthy athletes. Chi-squared tests were used to compare the strategy selection between athletic groin pain patients and healthy athletes.

RESULTS

There were no differences between groups in consistency in movement strategy selection (>80%). Athletic groin pain patients tended to select a knee dominant movement strategy whereas healthy athletes preferred an ankle dominant movement strategy.

CONCLUSIONS

The consistency observed in athletic groin pain patients supports the implementation of movement strategy assessments to inform AGP rehabilitation programmes tailored to athletes' deficiencies. Such assessments could help enhance the success of athletic groin pain rehabilitation. Differences in movement strategy selection might not be associated with injury state since there were no differences between athletic groin pain patients and healthy athletes.

Does athletic groin pain affect the muscular co-contraction during a change of direction

BACKGROUND

Groin pain is one of the common problems in multidirectional sports. It seems that abnormal muscular activity and improper movement strategy led to prolongation and high rate of this injury. Therefore, the aim of this study was to Comparing the Average amplitude of Electromyography (AEMG), co-contraction ratio (CCR) of selected thigh and thoracic muscle during turning in individuals with chronic groin pain and healthy individuals.

METHODS

Surface electromyography was collected from the internal oblique/transversus abdominis (IO/TrA), multifidus (MF), adductor Longus (AL) and gluteus Medius (GM) for AEMG and CCR analyzed in 16-males with LSGP and 16-controls in four motion phases during 11 cycles of gait coupled with turning.

RESULTS

Results revealed that in the AEMG apart from the third phase in the muscle of the IO/ Tr. A muscle and in the second phase in the MF muscle in the trunk and in the third phase in the muscle of the AL and the fourth phase in the GM foot Left There was a significant difference in other phases. There was a significant difference in the CCR, except in the second phase of the trunk and the fourth phase of the left foot in the rest of the phases.

CONCLUSIONS

It seems that in athletes with LSGP, have selective muscular activation and CCR have during turning, that may be resulting in compensatory strategies and movement control defects, which may be a useful tool to predict LSGP occurrence in players with a history of groin pain.

Objective classification and scoring of movement deficiencies in patients with anterior cruciate ligament reconstruction

Motion analysis systems are widely employed to identify movement deficiencies-e.g. patterns that potentially increase the risk of injury or inhibit performance. However, findings across studies are often conflicting in respect to what a movement deficiency is or the magnitude of association to a specific injury. This study tests the information content within movement data using a data driven framework that was taught to classify movement data into the classes: NORM, ACLOP and ACLNO OP, without the input of expert knowledge. The NORM class was presented by 62 subjects (124 NORM limbs), while 156 subjects with ACL reconstruction represented the ACLOP and ACLNO OP class (156 limbs each class). Movement data from jumping, hopping and change of direction exercises were examined, using a variety of machine learning techniques. A stratified shuffle split cross-validation was used to obtain a measure of expected accuracy for each step within the analysis. Classification accuracies (from best performing classifiers) ranged from 52 to 81%, using up to 5 features. The exercise with the highest classification accuracy was the double leg drop jump (DLDJ; 81%), the highest classification accuracy when considering only the NORM class was observed in the single leg hop (81%), while the DLDJ demonstrated the highest classification accuracy when considering only for the ACLOP and ACLNO OP class (84%). These classification accuracies demonstrate that biomechanical data contains valuable information and that it is possible to differentiate normal from rehabilitating movement patterns. Further, findings highlight that a few features contain most of the information, that it is important to seek to understand what a classification model has learned, that symmetry measures are important, that exercises capture different qualities and that not all subjects within a normative cohort utilise 'true' normative movement patterns (only 27 to 71%).

The Effect of Angle and Velocity on Change of Direction Biomechanics: An Angle-Velocity Trade-Off

Changes of direction (CODs) are key manoeuvres linked to decisive moments in sport and are also key actions associated with lower limb injuries. During sport athletes perform a diverse range of CODs, from various approach velocities and angles, thus the ability to change direction safely and quickly is of great interest. To our knowledge, a comprehensive review examining the influence of angle and velocity on change of direction (COD) biomechanics does not exist. Findings of previous research indicate the biomechanical demands of CODs are 'angle' and 'velocity' dependent and are both critical factors that affect the technical execution of directional changes, deceleration and reacceleration requirements, knee joint loading, and lower limb muscle activity. Thus, these two factors regulate the progression and regression in COD intensity. Specifically, faster and sharper CODs elevate the relative risk of injury due to the greater associative knee joint loading; however, faster and sharper directional changes are key manoeuvres for successful performance in multidirectional sport, which subsequently creates a 'performance-injury conflict' for practitioners and athletes. This conflict, however, may be mediated by an athlete's physical capacity (i.e. ability to rapidly produce force and neuromuscular control). Furthermore, an 'angle-velocity trade-off' exists during CODs, whereby faster approaches compromise the execution of the intended COD; this is influenced by an athlete's physical capacity. Therefore, practitioners and researchers should acknowledge and understand the implications of angle and velocity on COD biomechanics when: (1) interpreting biomechanical research; (2) coaching COD technique; (3) designing and prescribing COD training and injury reduction programs; (4) conditioning athletes to tolerate the physical demands of directional changes; (5) screening COD technique; and (6) progressing and regressing COD intensity, specifically when working with novice or previously injured athletes rehabilitating from an injury.

Epidemiology of Hip and Groin Injuries in Collegiate Athletes in the United States

Background:

Hip and groin pain is a common complaint among athletes. Few studies have examined the epidemiology of hip and groin injuries in collegiate athletes across multiple sports.

Purpose:

To describe the rates, mechanisms, sex-based differences, and severity of hip/groin injuries across 25 collegiate sports.

Study Design:

Descriptive epidemiology study.

Methods:

Data from the 2009-2010 through 2013-2014 academic years were obtained from the National Collegiate Athletic Association Injury Surveillance Program (NCAA ISP). The rate of hip/groin injuries, mechanism of injury, time lost from competition, and need for surgery were calculated. Differences between sex-comparable sports were quantified using rate ratios (RRs) and injury proportion ratios (IPRs).

Results:

In total, 1984 hip/groin injuries were reported, giving an overall injury rate of 53.06 per 100,000 athlete-exposures (AEs). An adductor/groin tear was the most common injury, comprising 24.5% of all injuries. The sports with the highest rates of injuries per 100,000 AEs were men’s soccer (110.84), men’s ice hockey (104.90), and women’s ice hockey (76.88). In sex-comparable sports, men had a higher rate of injuries per 100,000 AEs compared with women (59.53 vs 42.27, respectively; RR, 1.41 [95% CI, 1.28-1.55]). The most common injury mechanisms were noncontact (48.4% of all injuries) and overuse/gradual (20.4%). In sex-comparable sports, men had a greater proportion of injuries due to player contact than women (17.0% vs 3.6%, respectively; IPR, 4.80 [95% CI, 3.10-7.42]), while women had a greater proportion of injuries due to overuse/gradual than men (29.1% vs 16.7%, respectively; IPR, 1.74 [95% CI, 1.46-2.06]). Overall, 39.3% of hip/groin injuries resulted in time lost from competition. Only 1.3% of injuries required surgery.

Conclusion:

Hip/groin injuries are most common in sports that involve kicking or skating and sudden changes in direction and speed. Most hip/groin injuries in collegiate athletes are noncontact and do not result in time lost from competition, and few require surgery. This information can help guide treatment and prevention measures to limit such injuries in male and female collegiate athletes.

Clinical Examination, Diagnostic Imaging, and Testing of Athletes With Groin Pain: An Evidence-Based Approach to Effective Management

Synopsis Groin pain is common in athletes who participate in multidirectional sports and has traditionally been considered a difficult problem to understand, diagnose, and manage. This may be due to sparse historical focus on this complex region in sports medicine. Until recently, there has been little agreement regarding terminology, definitions, and classification of groin pain in athletes. This has made clear communication between clinicians difficult, and the results of research difficult to interpret and implement into practice. However, during the past decade, the field has evolved rapidly, and an evidence-based understanding is now emerging. This clinical commentary discusses the clinical examination (subjective history, screening, physical examination); imaging; testing of impairments, function, and performance; and management of athletes with groin pain in an evidence-based framework. J Orthop Sports Phys Ther 2018;48(4):239-249. Epub 6 Mar 2018. doi:10.2519/jospt.2018.7850.

Is stiffness related to athletic groin pain?

Athletic groin pain (AGP) is a common injury prevalent in field sports. One biomechanical measure that may be of importance for injury risk is stiffness. To date, [corrected] however, stiffness has not been examined in AGP. The primary aim was to determine whether AGP affects vertical and joint stiffness and if so, whether successful rehabilitation is associated with a change in stiffness. Sixty-five male patients with AGP and fifty male controls were recruited to this study. Assessment included a biomechanical examination of stiffness during a lateral hurdle hop test. Subjects with AGP were tested pre- and post-rehabilitation, while controls were tested once. AGP subjects were cleared for return to play in a median time of 9.14 weeks (5.14-29.0). Stiffness was significantly different at pre-rehabilitation in comparison with controls for three [corrected] of the ten stiffness values examined: ankle plantar flexor, knee extensor, hip abductor, and vertical stiffness (P <  .05, D = 0.38-0.81). [corrected]. Despite clearance for return to play, of these four variables, only hip abductor stiffness changed significantly from pre- to post-rehabilitation (P = .05, D = 0.36) [corrected] to become non-significantly different to the uninjured group (P = .23, D = 0.23). [corrected]. These findings suggest that hip abductor stiffness may represent a target for AGP rehabilitation. Conversely, given the clearance for return to play, the lower sagittal plane and vertical stiffness in the AGP group in comparison with the uninjured controls likely represents either a compensatory mechanism to reduce the risk of further injury or a consequence of neuromuscular detraining.

Clinical and biomechanical outcomes of rehabilitation targeting intersegmental control in athletic groin pain: prospective cohort of 205 patients

Background

Clinical assessments and rehabilitation in athletic groin pain (AGP) have focused on specific anatomical structures and uniplanar impairments rather than whole body movement.

Objective

To examine the effectiveness of rehabilitation that targeted intersegmental control in patients with AGP and to investigate post rehabilitation changes in cutting biomechanics.

Methods

Two hundred and five patients with AGP were rehabilitated focusing on clinical assessment of intersegmental control, linear running and change of direction mechanics in this prospective case series. Hip and Groin Outcome Score (HAGOS) was the primary outcome measure. Secondary measures included pain-free return to play rates and times, pain provocation on squeeze tests and three-dimensional (3D) biomechanical analysis during a 110° cutting manoeuvre.

Results

Following rehabilitation, patients demonstrated clinically relevant improvements in HAGOS scores (effect size (ES): 0.6–1.7). 73% of patients returned to play pain-free at a mean of 9.9 weeks (±3.5). Squeeze test values also improved (ES: 0.49–0.68). Repeat 3D analysis of the cutting movement demonstrated reductions in ipsilateral trunk side flexion (ES: 0.79) and increased pelvic rotation in the direction of travel (ES: 0.76). Changes to variables associated with improved cutting performance: greater centre of mass translation in the direction of travel relative to centre of pressure (ES: 0.4), reduced knee flexion angle (ES: 0.3) and increased ankle plantar flexor moment (ES: 0.48) were also noted.

Conclusions

Rehabilitation focused on intersegmental control was associated with improved HAGOS scores, high rates of pain-free return to sporting participation and biomechanical changes associated with improved cutting performance across a range of anatomical diagnoses seen in AGP.

A COMBINED TREATMENT APPROACH EMPHASIZING IMPAIRMENT-BASED MANUAL THERAPY AND EXERCISE FOR HIP-RELATED COMPENSATORY INJURY IN ELITE ATHLETES: A CASE SERIES

BACKGROUND/PURPOSE

Athletes experiencing hip, groin, and low back pain often exhibit similar clinical characteristics. Individuals with hip, groin and low back pain may have the presence of multiple concurrent pathoanatomical diagnoses. Regardless, similar regional characteristics and dysfunction may contribute to the patient's chief complaint, potentially creating a sub-group of individuals that may be defined by lumbopelvic and hip mobility limitations, motor control impairments, and other shared clinical findings. The purpose of this case series is to describe the conservative management of elite athletes, within the identified aforementioned sub-group, that emphasized regional manual therapy interventions, and therapeutic exercise designed to improve lumbopelvic and hip mobility, stability and motor control.

CASE DESCRIPTIONS

Five elite athletes were clinically diagnosed by a physical therapist with primary pathologies including adductor-related groin pain (ARGP), femoral acetabular impingement (FAI) with acetabular labral lesion and acute, mechanical low back pain (LBP). Similar subjective, objective findings and overall clinical profiles were identified among all subjects. Common findings aside from the chief complaint included, but were not limited to, decreased hip range of motion (ROM), impaired lumbopelvic motor control and strength, lumbar hypomobility in at least one segment, and a positive hip flexion-adduction-internal rotation (FADIR) special test. A three-phase impairment-based physical therapy program was implemented to resolve the primary complaints and return the subjects to their desired level of function. Acute phase rehabilitation consisted of manual therapy and fundamental motor control exercises. Progression to the sub-acute and terminal phases was based on improved subjective pain reports and progress with functional impairments. As the subjects progress through the rehabilitation phases, the delivery of physical therapy interventions were defined by decreased manual therapies and an increased emphasis and priority on graded exercise.

OUTCOMES

Significant reductions in reported pain (>2 points Numeric Pain Rating Scale), improved reported function via functional outcome measures (Hip and Groin Outcome Score), and continued participation in sport occurred in all five cases without the need for surgical intervention.

DISCUSSION

The athletes described in this case series make up a common clinical sub-group defined by hip and lumbopelvic mobility restrictions, lumbopelvic and lower extremity motor control impairments and potentially other shared clinical findings. Despite differences in pathoanatomic findings, similar objective findings were identified and similar treatment plans were applied, potentially affecting the movement system as a whole. Subjects were conservatively managed allowing continued participation in sport within their competitive seasons.

CONCLUSION

Comprehensive conservative treatment of the athletes with shared impairments, as described in this case series, may be of clinical importance when managing athletes with hip, groin, and low back pain.

LEVEL OF EVIDENCE

Therapy, Level 4, Case Series.

Effects of a dynamic core stability program on the biomechanics of cutting maneuvers: A randomized controlled trial

Deficits in trunk control predict ACL injuries which frequently occur during high-risk activities such as cutting. However, no existing trunk control/core stability program has been found to positively affect trunk kinematics during cutting activities. This study investigated the effectiveness of a 6-week dynamic core stability program (DCS) on the biomechanics of anticipated and unanticipated side and crossover cutting maneuvers. Thirty-one male, varsity footballers participated in this randomized controlled trial. Three-dimensional trunk and lower limb biomechanics were captured in a motion analysis laboratory during the weight acceptance phase of anticipated and unanticipated side and crossover cutting maneuvers at baseline and 6-week follow-up. The DCS group performed a DCS program three times weekly for 6 weeks in a university rehabilitation room. Both the DCS and control groups concurrently completed their regular practice and match play. Statistical parametric mapping and repeated measures analysis of variance were used to determine any group (DCS vs control) by time (pre vs post) interactions. The DCS resulted in greater internal hip extensor (P=.017, η² =0.079), smaller internal knee valgus (P=.026, η² =0.076), and smaller internal knee external rotator moments (P=.041, η² =0.066) during anticipated side cutting compared with the control group. It also led to reduced posterior ground reaction forces for all cutting activities (P=.015-.030, η² =0.074-0.105). A 6-week DCS program did not affect trunk kinematics, but it did reduce a small number of biomechanical risk factors for ACL injury, predominantly during anticipated side cutting. A DCS program could play a role in multimodal ACL injury prevention programs.