Quadriceps strength and functional performance after anterior cruciate ligament reconstruction in professional soccer players at time of return to sport

Poor quadriceps strength has been associated with poor outcome after anterior cruciate ligament (ACL) reconstruction (ACLR). This study aims to assess quadriceps strength, muscle inhibition, and hop test performance in professional soccer players after ACLR. Fifteen professional soccer players (age 22.3 ± 3.1 years, body mass 81.0 ± 11.5 kg, and height 1.75 ± 0.1 m) who had undergone ACLR participated. Isometric, eccentric, and concentric quadriceps strength was assessed, along with quadriceps inhibition and single and cross-over hop performance, at the time of return to full-time unrestricted play. In comparison with the uninjured leg, the ACLR leg demonstrated large significant (d ≥ 0.84, p < 0.01) deficits in isometric, eccentric, and concentric quadriceps strength, quadriceps inhibition, and hop distance. Over 80% of the players failed to exceed the limb symmetry criteria of ≥90% for strength tests, although 75% of the cohort passed the ≥90% criteria for hop tests. The outcome from ACLR in professional soccer players who received full-time intensive rehabilitation has not previously been reported in detail. There were significant deficits in quadriceps strength at the time of return to sport, whereas hop testing, a commonly used outcome measure, failed to show the same levels of deficit. These deficits in quadriceps function may have implications for the development of ongoing knee symptoms and risk of future ACL injury. If this proves to be the case, then it would seem that greater attention should be paid to re-establishing full quadriceps strength before returning to unrestricted sporting activity

Patellofemoral joint loads in ACL reconstructed elite athletes during running at time of return to sport

Background: Patellofemoral joint pain and degeneration is common in patients who undergo ACL reconstruction (ACLR). The presence of patellofemoral joint pain significantly impacts on the ability to continue to participate in sport and may even have a bearing on participation in activities of daily living. What is currently unclear is the mechanisms behind this process, previous research has identified altered patellofemoral joint loading in individuals with patellofemoral joint pain when running. It is unclear if this process is occurring following ACLR. Hypothesis/Purpose: To assess the patellofemoral joint stresses during running in ACLR knees and compare the findings to non-injured knee and matched control knees. Study Design: Cohort study Methods: Thirty four elite sports practitioners who had undergone ACLR and thirty four age and sex matched controls participated in the study. The participants had their running gait assessed using 3D motion capture, and knee loads and forces calculated using inverse dynamics. Results: There was a significance difference in knee extensor moment, knee flexion angles, patellofemoral contact force (around 23% greater), and patellofemoral contact pressure (around 27% greater) between the ACLR and non-injured limb (p≤0.04) and the ACLR and control limb (p≤0.04), with no significant difference between the non-injured and control limbs (p≥0.44). Conclusion: Significantly greater levels of patellofemoral joint stress and load were found in the ACLR knee compared to the non-injured and control knees. Clinical Relevance: Altered levels of patellofemoral stress in the ACLR knee during running may predispose these individuals to patellofemoral joint pain

The relationship between 2D knee valgus angle during single leg squat, single leg land and drop jump screening tests

Context: Injuries to the anterior cruciate ligament (ACL) and patellofemoral joint (PFJ) are a significant problem in female athletes. A number of screening tasks have been used in the literature to identify those at greatest risk of injury. To date, no study has examined the relationship in 2-dimensional (2D) knee valgus between common screening tasks to determine whether individuals exhibit similar movement patterns across tasks. Objective: To establish whether frontal-plane projection angle (FPPA) during the single-leg squat (SLS), single-leg land (SLL), and drop jump (DJ) are related. Design: Cross-sectional study. Setting: University laboratory. Participants: 52 national-league female football players and 36 national-league female basketball players. Main Outcome Measures: 2D FPPA during the SLS, SLL, and DJ screening tasks. Results: Significant correlations were found between tasks. FPPA in the SLS was significantly correlated with SLL (r = .52) and DJ (r = .30), whereas FPPA in the SLL was also significantly correlated to DJ (r = .33). FPPA was significantly greater in the SLS than in the SLL (P &lt; .001) and DJ (P &lt; .001) and in the SLL than in the DJ (P &lt; .001). Conclusion: The results showed that 2D FPPA is correlated across the SLS, SLL, and DJ tasks. However, significantly greater FPPA values in the unilateral tasks suggest that the DJ may not identify risk of injury in sports where primary injury mechanisms are during unilateral loading tasks. Therefore, it is recommended that both unilateral and bilateral tasks be included when screening for ACL and PFJ injury risk

A comparison of frontal plane projection angle across landing tasks in female gymnasts

The aim of this study was to compare FPPA between three landing tasks and determine the reliability of FPPA in 15 competitive female gymnasts (age 13.5 ± 2.07 years). Reliability of FPPA was highest in the drop landing task, with no learning effect present. The backaway task showed the greatest FFPA (right: 26.75 ± 9.57°; left: 19.67 ± 9.03°), which was greater than the drop landing task (right: 19.07 ± 7.42°; left: 12.18 ± 4.83°). Individuals involved in training young female gymnasts are encouraged to screen for injury risk using FPPA during the drop landing task

Braking characteristics during cutting and pivoting in female soccer players

Biomechanical studies into changing direction focus on final contact (FC), whilst limited research has examined penultimate contact (PEN). The aim of this study was to explore the kinematic and kinetic differences between PEN and FC of cutting and pivoting in 22 female soccer players (mean ± SD; age: 21 ± 3.1 years, height: 1.68 ± 0.07 m, mass: 58.9 ± 7.3 kg). Furthermore, the study investigated whether horizontal force-time characteristics during PEN were related to peak knee abduction moments during FC. Three dimensional motion analyses of cutting and pivoting on the right leg were performed using Qualysis ‘Pro-reflex’ infrared cameras (240Hz). Ground reaction forces (GRF) were collected from two AMTI force platforms (1200Hz) to examine PEN and FC. Both manoeuvres involved significantly (P < 0.05) greater knee joint flexion angles, peak horizontal GRF, but lower average horizontal GRF during PEN compared to FC. Average horizontal GRF during PEN (R = -0.569, R2 = 32%, P = 0.006) and average horizontal GRF ratio (R = 0.466, R2 = 22%, P = 0.029) were significantly related to peak knee abduction moments during the FC of cutting and pivoting, respectively. The results indicate PEN during pre-planned changing direction helps reduce loading on the turning leg where there is greater risk of injuries to knee ligaments

Variation in pelvic morphology may prevent the identification of anterior pelvic tilt

Pelvic tilt is often quantified using the angle between the horizontal and a line connecting the anterior superior iliac spine (ASIS) and the posterior superior iliac spine (PSIS). Although this angle is determined by the balance of muscular and ligamentous forces acting between the pelvis and adjacent segments, it could also be influenced by variations in pelvic morphology. The primary objective of this anatomical study was to establish how such variation may affect the ASIS-PSIS measure of pelvic tilt. In addition, we also investigated how variability in pelvic landmarks may influence measures of innominate rotational asymmetry and measures of pelvic height. Thirty cadaver pelves were used for the study. Each specimen was positioned in a fixed anatomical reference position and the angle between the ASIS and PSIS measured bilaterally. In addition, side-to-side differences in the height of the innominate bone were recorded. The study found a range of values for the ASIS-PSIS of 0–23 degrees, with a mean of 13 and standard deviation of 5 degrees. Asymmetry of pelvic landmarks resulted in side-to-side differences of up to 11 degrees in ASISPSIS tilt and 16 millimeters in innominate height. These results suggest that variations in pelvic morphology may significantly influence measures of pelvic tilt and innominate rotational asymmetry

A 10% increase in step rate improves running kinematics and clinical outcomes in runners with patellofemoral pain at 4 weeks and 3 months

Background: Aberrant frontal plane hip and pelvis kinematics have been frequently observed in runners with patellofemoral pain (PFP). Gait retaining interventions have been shown to improve running kinematics and may therefore be beneficial in runners with PFP. Purpose: the aim of this study was to investigate whether a 10% increase in running step rate influences frontal plane kinematics of the hip and pelvis, as well as clinical outcomes in runners with PFP. Study Design: Case Series Methods: Runners with PFP underwent a 3D gait analysis to confirm the presence of aberrant frontal plane hip and pelvis kinematics at baseline. Twelve participants with frontal plane hip and pelvis kinematics one standard deviation above a reference database, were invited to participate in the gait retraining intervention. Running kinematics along with clinical outcomes of pain and functional measures were recorded at baseline, 4 weeks following retraining and 3-months. Gait retraining consisted of a single session where step rate was increased by 10% using an audible metronome. Participants were asked to continue their normal running while self-monitoring their step rate using a global positioning system watch and audible metronome. Results: Following gait retraining significant improvements in running kinematics and clinical outcomes were observed at 4 week and 3-month follow up. Repeated measures ANOVA with post hoc Bonferroni (p <0.016) showed significant reductions in peak contralateral pelvic drop (Mean Difference [MD], 3.12⁰; 95% Confidence Interval [CI], 1.88⁰, 4.37⁰), hip adduction (MD, 3.99⁰; 95% CI, 2.01⁰, 5.96⁰) and knee flexion (MD, 4.09⁰; 95% CI, 0.04⁰, 8.15⁰), as well as significant increases in self-reported weekly running volume (MD, -13.78km; 95% CI, -22.93km, -4.62km) and longest run pain free (MD, -6.84km; 95% CI, -10.62km, -3.05km). Friedman test with post hoc Wilcoxon signed-rank showed significant improvements in Numerical Rating Scale for worst pain in the past week and Lower Extremity Functional Scale. Conclusion: A single session of gait retraining using a 10% increase in step rate results in significant improvements in running kinematics, pain and function in runners with PFP. These improvements were maintained at 3-month follow up. It is important to assess for aberrant running kinematics at baseline to ensure gait interventions are targeted appropriately. Clinical Relevance: Step rate modification is a simple method of gait retraining that can be easily integrated into clinical practice and running outside of a laboratory setting

Does the Powers™ strap influence the lower limb biomechanics during running?

Previous research has reported a prevalence of running related injuries in 25.9% to 72% of all runners. A greater hip internal rotation and adduction during the stance phase in running has been associated with many running related injuries, such as patellofemoral pain. Researchers in the USA designed a treatment device 'the PowersTM strap' to facilitate an external rotation of the femur and to thereby control abnormal hip and knee motion during leisure and sport activities. However, to date no literature exists to demonstrate whether the PowersTM strap is able to reduce hip internal rotation during running. 22 healthy participants, 11 males and 11 females (age: 27.45 ±4.43 years, height: 1.73 ± 0.06m, mass: 66.77 ±9.24kg) were asked to run on a 22m track under two conditions: without and with the PowersTM strap. Threedimensional motion analysis was conducted using ten Qualisys OQUS 7 cameras (Qualisys AB, Sweden) and force data was captured with three AMTI force plates (BP600900, Advanced Mechanical Technology, Inc.USA). Paired sample t-tests were performed at the 95% confidence interval on all lower limb kinematic and kinetic data. The PowersTM strap significantly reduced hip and knee internal rotation throughout the stance phase of running. These results showed that the PowersTM strap has the potential to influence hip motion during running related activities, in doing so this might be beneficial for patients with lower limb injuries. Future research should investigate the influence of the PowersTM strap in subjects who suffer from running related injuries, such as patellofemoral pain

Is there a pathological gait associated with common soft tissue running injuries?

Background: Previous research has demonstrated clear associations between specific running injuries and patterns of lower limb kinematics. However, there has been minimal research investigating whether the same kinematic patterns could underlie multiple different soft tissue running injuries. If they do, such kinematic patterns could be considered global contributors to running injury. Hypothesis: Injured runners will demonstrate differences in running kinematics when compared to injury free controls. These kinematic patterns will be consistent amongst injury subgroups. Study Design: Case- Control Study Methods: We studied 72 injured runners and 36 healthy controls. The injured group contained four subgroups of runners with either patellofemoral pain, iliotibial band syndrome, medial tibial stress syndrome or Achilles tendinopathy (n = 18 each). Three-dimensional running kinematics were compared between injured and healthy runners and then between the four injured subgroups. A logistic regression model was used to determine which parameters could be used to identify injured runners. Results: The injured runners demonstrated greater contralateral pelvic drop and forward trunk lean at mid-stance and a more extended knee and dorsiflexed ankle at initial contact. The subgroup ANOVA found these kinematic patterns were consistent across each of the four injury subgroups. Contralateral pelvic drop was found to be the most important variable predicting classification of participants as healthy/injured. Importantly, for every 1° increase in pelvic drop there was an 80% increase in the odds of being classified injured. Conclusion: This study identified a number of global kinematic contributors to common running injuries. In particular, we found injured runners to run with greater peak contralateral pelvic drop and trunk forward lean, as well as an extended knee and dorsiflexed ankle at initial contact. Contralateral pelvic drop appears to be the variable most strongly associated with common running related injuries. Clinical Relevance: The identified kinematic patterns may prove beneficial for clinicians when assessing for biomechanical contributors to running injuries

Influence of the Powers™ strap on pain and lower limb biomechanics in individuals with patellofemoral pain

Background: Abnormal biomechanics, especially hip internal rotation and adduction are known to be associated with patellofemoral pain (PFP). The PowersTM strap was designed to decrease hip internal rotation and to thereby stabilise the patellofemoral joint. Objectives: This study aimed to investigate whether the PowersTM strap influenced pain and lower limb biomechanics during running and squatting in individuals with PFP. Methods: 24 individuals with PFP were recruited using advertisements that were placed at fitness centres. They were asked to perform a single leg squat task (SLS) and to run on an indoor track at their own selected speed during two conditions: with and without the PowersTM strap. Immediate pain was assessed with the numeric pain rating scale. Three-dimensional motion and ground reaction force data were collected with 10 Qualisys cameras and 3 AMTI force plates. Results: Immediate pain was significantly reduced with the PowersTM strap (without the PowersTM strap: 4.04±1.91; with the PowersTM strap: 1.93±2.13). The PowersTM strap condition significantly increased hip external rotation by 4.7° during the stance phase in running and by 2.5° during the single leg squat task. Furthermore, the external knee adduction moment during the SLS and running increased significantly. Conclusion: This study assessed the effect of the PowersTM strap on lower limbs kinematics and kinetics in individual with PFP. The results suggest that the PowersTM strap has the potential to improve abnormal hip motion. Furthermore, the PowersTM strap demonstrated an ability to significantly reduce pain during functional tasks in patients with PFP