The biomechanical evaluation of athletic groin pain

Introduction: Athletic groin pain (AGP) is a common injury in sports involving repetitive twisting, kicking and turning (Werner et al., 2009; Thorborg et al., 2017). In male soccer for example, AGP incidence accounts for 4 -19% of all injuries (Walden, Hagglund and Ekstrand, 2015). Despite this, there remains a dearth of literature investigating the three-dimensional biomechanics of AGP. The primary aim of this PhD thesis is to evaluate the biomechanical factors affected by AGP to enhance our understanding of this injury. Methods: This thesis incorporates the work from eight investigations including one published systematic review incorporated in the review of literature, two methodological studies and five experimental investigations. As a body of work, this is the one of the largest investigations of AGP biomechanics conducted to date as it includes an investigation of over 200 AGP patients and 85 uninjured subjects. Results and Conclusion: Multiple biomechanical factors were identified that may be related to AGP. The mechanics of the trunk and hip are commonly affected by this injury, particularly in the frontal plane, and may represent targets for rehabilitation. The ankle joint was also consistently and strongly identified as being affected by AGP but generally failed to change significantly from pre- to post- rehabilitation. As such, future research is warranted to ascertain if AGP rehabilitation could be further enhanced with a focus on improving ankle function. Given that variability and complexity appear to be affected by AGP with large effect sizes, it is suggested that the rehabilitation of AGP should follow a dynamic systems theory approach (Newell 1986). The results from this PhD thesis have made novel contributions on an empirical, theoretical, methodological and practical level and the findings can help guide clinical practice and the design of future prospective research

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 (&gt;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.</p

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 (&gt;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.</p

THE EFFECTS OF AN EXERCISE INTERVENTION ON THE BIOMECHANICS OF AN ATHLETIC GROIN PAIN COHORT DURING THE LATERAL HURDLE HOP

The purpose of this study was to determine the kinematic and kinetic variables that may be of importance in the investigation of athletic groin pain (AGP). This was achieved by examining the 3D kinematics and kinetics of 70 AGP patients, recorded during a lateral hurdle hop, pre and post a successful exercise rehabilitation program. Results from the Copenhagen Hip and Groin Outcome Score questionnaire demonstrated significant improvements in 5 out of the 6 subscales. Analysis of characterising phases was used to examine kinematic and kinetic changes. Multiple significant changes were identified in both angles at the pelvis, hip and thorax and moments at the hip. Findings of this study provide an insight into the kinematic and kinetic variables of importance in AGP

CHANGES IN THE BIOMECHANICS OF A REACTIVE CUTTING MANOEUVRE IN AN ATHLETIC GROIN PAIN COHORT FOLLOWING A SUCCESSFUL REHABILITATION INTERVENTION

Athletic groin pain (AGP) is prevalent in field sports that require rapid changes of direction. The purpose of this study was to investigate the kinetic and kinematic changes that occurred in an unplanned reactive cutting manoeuvre following a successful rehabilitation intervention. Kinematics and kinetics were analysed using statistical parametric mapping in 23 patients before and after an exercise intervention programme. Significant improvements were found in all subscales of the Copenhagen Hip and Groin Outcome Score and biomechanical changes were identified at the pelvis, knee and ankle. These findings provide insight into mechanical variables of potential importance in AGP as identified during a manoeuvre based on a common sporting task

Athletic groin pain: a biomechanical diagnosis

Introduction: Chronic athletic groin pain is commonly experienced in a range of football codes including soccer (Holmich et al. 2014) and gaelic football (Murphy et al. 2012). Much debate surrounds the specific aetiology of AGP but several authors have implicated, at least in part, abnormal movement control and loading in and around the hip and pelvis during play (Rabe et al. 2010, Pizarri et al. 2008). Movement control during change of direction cutting is of particular interest as it is this dynamic movement that is frequently associated with groin pain development (Falvey et al. 2009). No previous studies have attempted to describe the key characteristics of cutting mechanics that may be prevalent in AGP populations, that is, what are the potential biomechanical diagnoses that exist in this cohort. Purpose: To describe the key characteristics of three dimensional cutting mechanics that exist within a large cohort of AGP patients. Methods: Four hundred (n = 400) recreational field sports players diagnosed with chronic athletic groin pain were recruited (mean ± SD: age, 27 ± 8 years; height, 1.80 ± 0.06m; mass, 81.9 ± 9.4 kg; time with groin pain, 66.2 ± 96.7 weeks). The study attained ethical approval and participants completed and signed an informed consent form before taking part. Participants underwent biomechanical testing before commencing rehabilitation. Testing involved three trials (both left and right side) of a change-of-direction cut. For the cut, participants ran as fast as possible for five meters toward a marker placed on the floor and performed an approximate 75° cut before running maximally to the finish. An eight camera 3D motion analysis system (Vicon - Bonita B10, UK), synchronized with two 40x60cm force platforms (AMTI – BP400600, USA), collected biomechanical data. Data analysis utilized the mean of each participant’s three trials on the symptomatic side, or for those with bi-lateral groin pain (n = 80), the side that was most symptomatic. A cluster analysis was undertaken using kinematic data as input (ankle, knee, hip, pelvis and trunk angles). Repeated measure ANOVAs with bonferroni post-hoc corrections were then used to determine between sub-group differences in biomechanical variables of interest. A significance level of (α = 0.05) was adopted. Results: Three distinct subgroups were created: C1 (containing 40% of participants), C2 (containing 15% of participants) and C3 (containing 45% of participants). C1 had significantly greater hip flexion and hip-pelvo-trunk rotation than C2 and C3. C3 and C2 had significantly greater hip-pelvo-trunk lateral side flexion than C1. C2 had significantly greater trunk flexion than both C1 and C3. Conclusion: Different sub-groups existed within the large cohort that exhibited distinctive cutting mechanics. Our findings may go some way toward identifying the potential cutting characteristics/diagnoses that exist in AGP patients. Rehabilitation specilaists may look to utilise such information when attempting to affect their patients cutting mechanics. Future studies are required to confirm the clinical relevance of the cutting characteristics/diagnoses identified herein. An examination of the effects of individualising groin rehabilitation programs based on a cutting mechanics assessment appears warrented. Given the inter-individual differences in cutting mechanics observed, caution is advised in the use of traditional group based analyses in future AGP biomechanical studies. This is due to the potential masking of significant findings when using heterogenous data (Bates 2005). Clustering techniques, such as employed here, may be useful in identifying homogenous sub-groups before undertaking more traditional statistical analyses

A comparison of asymmetry in athletic groin pain patients and elite rugby union players using analysis of characterising phases

This study compared levels of inter limb asymmetry between field sports players with athletic groin pain and international rugby union players. Three dimensional kinematics and kinetics were recorded for the single leg hurdle hop and side cut movement. Analysis of characterising phases was utilised to identify significant differences in asymmetry between the two groups. The rugby union group had significantly greater asymmetry in some kinematic variables and hip kinetic variables at the beginning of the exercises. Overall however, the athletic groin pain group displayed greater asymmetry, particularly in hip moments compared with the rugby union group. These results suggest that an aspect of rehabilitation for athletic groin pain should focus on reducing asymmetric hip moments

A COMPARISON OF ASYMMETRY IN ATHLETIC GROIN PAIN PATIENTS AND ELITE RUGBY UNION PLAYERS USING ANALYSIS OF CHARACTERISING PHASES

This study compared levels of inter limb asymmetry between field sports players with athletic groin pain and international rugby union players. Three dimensional kinematics and kinetics were recorded for the single leg hurdle hop and side cut movement. Analysis of characterising phases was utilised to identify significant differences in asymmetry between the two groups. The rugby union group had significantly greater asymmetry in some kinematic variables and hip kinetic variables at the beginning of the exercises. Overall however, the athletic groin pain group displayed greater asymmetry, particularly in hip moments compared with the rugby union group. These results suggest that an aspect of rehabilitation for athletic groin pain should focus on reducing asymmetric hip moments