MRI assessment of calf injuries in Australian Football League players: findings that influence return to play

Are return-to-play times longer in lower-limb muscle injuries involving the intramuscular tendon? A systematic review

OBJECTIVES

To determine the influence of severity and direction (craniocaudal length vs cross-sectional area) of intramuscular tendon tears in the lower limb on return-to-play times, compared to muscle injuries without intramuscular tendon involvement.

DESIGN

Systematic review with meta-analysis.

METHODS

AMED, CINAHL, SPORTDiscus, ScienceDirect, PubMed (MEDLINE) and Web-of-Science were searched from inception to 31st July 2023, retrieving 666 records, of which nine were deemed eligible. A random-effects meta-analysis was performed on time to return-to-play for British Athletics Muscle Injury Classification 'b' vs 'c'.

RESULTS

On the Quality in Prognosis Studies tool, one study had low risk of bias and eight had high risk. Using a best-evidence synthesis, no strong evidence emerged for a difference in time to return-to-play between injuries with or without intramuscular tendon involvement. Moderate evidence was found for an association between increased return-to-play time and the presence of "waviness" on magnetic resonance imaging and loss of tendon tension, but no association with longitudinal extent of tendon involvement. Pooled analysis revealed a medium effect-size difference between British Athletics Muscle Injury Classification 'b' and 'c' injuries, favouring classification 'b' (Hedges g = 0.67; 95% confidence interval 0.20 to 1.15; P = 0.002).

CONCLUSIONS

It remains difficult to provide an accurate prognosis for muscle injuries involving the intramuscular tendon due to high risk of bias and moderate heterogeneity across studies. Moderate evidence favoured the prognosis for injuries at the musculotendinous junction (British Athletics Muscle Injury Classification 'b') over intratendinous injuries (British Athletics Muscle Injury Classification 'c').

Rupture of the gastrocnemius muscle at its distal musculotendinous junction: conservative treatment and outcomes in 11 dogs

CASE HISTORY

Medical records from three veterinary referral centres and a university veterinary teaching hospital in Australia and the USA were reviewed to identify dogs with a diagnosis of distal gastrocnemius musculotendinous junction rupture (DGMJR) that were treated without surgery between 2007 and 2020.

CLINICAL AND IMAGING FINDINGS

All dogs (n = 11) presented with unilateral, pelvic limb lameness and bruising, swelling or pain on palpation at the distal musculotendinous junction. The diagnosis was confirmed with ultrasound or MRI in six dogs; radiographs were used to excluded stifle and tarsus pathology in four dogs; and five dogs were diagnosed on physical examination findings.

TREATMENT AND OUTCOME

All dogs were managed conservatively, either with complete confinement alone (n = 10; median 9 weeks), external coaptation alone (n = 1), or a combination of both (n = 4). Sporting dogs (n = 7) were completely confined (median 22 weeks) for longer periods than companion dogs (n = 3; median 5 weeks).A good to excellent outcome was achieved for all cases in this cohort. The seven sporting dogs achieved an excellent outcome; returning to their previous level of sport, with complete resolution of lameness and recovery of a normal tibiotarsal stance. The four companion dogs achieved a good outcome; returning to their previous level of activity but with persistently increased tibiotarsal standing angle compared to the contralateral limb.

CLINICAL RELEVANCE

Conservative treatment represents a viable treatment option for dogs with a rupture of the gastrocnemius muscle at its distal musculotendinous junction.

Normative isometric plantarflexion strength values for professional level, male rugby union athletes

OBJECTIVES

The primary aim was to establish normative values of isometric plantarflexor muscle strength in professional male rugby union players and compare forwards with backs. The secondary aims were to examine how individual playing position or age influences isometric plantarflexor strength.

DESIGN

Cross-sectional.

SETTING

Testing at professional rugby clubs.

PARTICIPANTS

355 players (201 forwards and 154 backs) from 9 clubs in the English Premiership club competition.

MAIN OUTCOME MEASURES

Maximal unilateral isometric plantarflexion strength was measured, using a Fysiometer C-Station, in a seated position with a flexed knee and in maximal available dorsiflexion. Values are reported normalised to body mass and specific to playing position.

RESULTS

Mean combined limb isometric plantarflexion strength for the group was 193.1 kg (SD 32) or 1.86 xBW. (SD 0.31). Forwards were significantly weaker than backs (forwards = 1.75xBW (SD 0.26), backs = 2.00xBW (SD 0.28) (p=<0.0001)). Age category revealed no influence on plantarflexor strength.

CONCLUSION

This study presents normative isometric plantarflexion strength values for professional male rugby union players. Forwards are typically relatively weaker than backs.

MRI findings prior to return to play as predictors of reinjury in professional athletes: a novel decision-making tool

BACKGROUND

Because MRI has shown great accuracy in assessing acute muscle injuries, identification of risk factors for reinjury before return to play (RTP) in professional athletes during the healing process could be very relevant. We assessed the value of MRI findings prior to RTP as predictors of reinjury.

METHODS

Retrospective observational study of 59 professional athletes, mean age 26 years, with first-time acute muscle injury and successful rehabilitation ready to RTP. They underwent MRI within 6 days of the injury and within 7 days prior to RTP. The primary outcome was reinjury. Risk of reinjury was assessed using radiological signs in control MRI scans before RTP. The risk was classified as low, medium or high when none, one or two radiological signs were observed, respectively.

RESULTS

Reinjury occurred in 9 participants, with a rate of 15.2%. None of the baseline MRI-related variables was significantly associated with reinjury. In the control MRI scan performed within 7 days prior to RTP, three independent findings were significantly associated with reinjury. These included transversal and/or mixed connective tissue gap (p = 0.002), intermuscular oedema (p = 0.015) and callus gap (p = 0.046). In the predictive model of the risk of reinjury, the presence of two of these radiological signs, together with interstitial feathery oedema, was associated with a high risk of recurrence (OR 29.58, 95% CI 3.86-226.64; p = 0.001).

CONCLUSIONS

In professional athletes with acute muscle injuries of the lower limbs successfully rehabilitated, some radiological signs on MRI performed shortly before RTP were associated with a high risk of reinjury.

Application of Image Processing Technology in the Diagnosis of Football Injury

With the hot development of football, sports injuries caused by football have also received special attention. In football games, although there are medical staff on and off the field always on call to protect the safety of players, because of the complexity of diagnosis work, medical staff can easily lead to diagnostic errors due to factors such as fatigue, which seriously affects the condition of athletes. Image processing is a technology that uses computer to process images, which can greatly overcome the uncertain factors brought by manual diagnosis. Based on this, this paper uses image processing technology and pattern recognition as technical means to explore the specific application of image processing in football injury diagnosis. This paper firstly takes football clubs as the main research object and analyzes and explores the specific utility of image segmentation and feature recognition in sports injury image processing. Then, starting from the relevant image features, the paper analyzes and compares the sensitivity of support vector machine pattern recognition and neural network pattern recognition in football injury diagnosis. This article comprehensively summarizes the application of image processing technology in the diagnosis of football injuries and puts forward constructive suggestions for its subsequent development. Experiments show that the effect of pattern recognition is often different for different injury parts of football. Among them, the sensitivity of pattern recognition based on image processing can reach 68.9%, and the detection rate of football injuries can also be maintained at about 81.2%. This fully shows that image processing technology can play an active role in the actual football injury diagnosis, and provide very valuable information for clinical diagnosis.

Calf Strain in Athletes

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Calf strain is a common condition. In high-performance athletes, calf strain contributes to a substantial absence from competition.

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Player age and history of a calf strain or other leg injury are the strongest risk factors for calf strain injury and reinjury.

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Although the diagnosis is often clinical, magnetic resonance imaging and ultrasound are valuable to confirm the location of the strain and the grade of injury.

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Nonoperative treatment is effective for most calf strain injuries. Operative management, although rarely indicated, may be appropriate for severe cases with grade-III rupture or complications.

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Further investigation is necessary to elucidate the benefits of blood flow restriction therapy, deep water running, lower-body positive pressure therapy, platelet-rich plasma, and stem cell therapy for calf strain rehabilitation.

Return to play protocols for musculoskeletal upper and lower limb injuries in tackle-collision team sports: A systematic review

Athletes in tackle-collision teams are at high risk of musculoskeletal injuries resulting in absence from play due to the high impact nature of the sport. There is a paucity of research to guide the management and assessment methods needed to facilitate the return to play (RTP) process. This review aimed to describe, synthesise and evaluate RTP protocols implemented for musculoskeletal injuries in tackle-collision teams. A systematic search of Scopus, PubMed, Web of Science and Ebsco Host was conducted for RTP management protocols and assessment modalities following upper and lower limb musculoskeletal injuries in tackle-collision team athletes. Prospective and retrospective quantitative controlled trials, cohort, case-control, case-series and cross-sectional observation studies published between January 2000 and March 2020 were considered. The main outcome measures were the proportion of athletes to RTP, associated time-loss and reinjury risk. 5265 articles were screened. 34 studies met the eligibility criteria of which 23 involved management and 11 assessment modalities. Management involved surgical or conservative strategies along with exercise-based rehabilitation. Assessment modalities included radiographic assessment, clinical evaluation and subjective ratings. Promising RTP management included progressive weight-bearing and exercised-based rehabilitation for ankle sprains as well as surgery, the use of a sling and exercise-based rehabilitation for shoulder instability. MRI scans showed promise in predicting time-loss following hamstring and calf strains in tackle-collision athletes. There are currently no clear guidelines for RTP after musculoskeletal injuries in tackle-collision sports. Future research should investigate efficient management strategies evaluated through valid and reliable assessment methods to better guide clinicians.

Muscle Strains in the Lower Extremity of Japanese Professional Baseball Players

Background

Predicting when athletes can return to play after muscle strains is not always simple because of difficulties in evaluating the severity of such injuries.

Purpose/Hypothesis

The purpose of this study was to evaluate the use of magnetic resonance imaging (MRI) to classify lower extremity muscle strains in Japanese professional baseball players. The hypothesis was that MRI grading can be used to diagnose the severity of muscle strains in the lower extremity and predict return to play in athletes.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 55 muscle strains occurred in the lower extremity of players on a professional baseball team between the 2006 and 2015 seasons; all players had undergone MRI examination. Age, player position, location of injury, cause of injury, and duration until return to play (in days) were extracted from the medical records. MRI scans were classified using the following system: grade 0, no abnormal findings; grade 1a, T2-weighted high intensity only between muscles; grade 1b, T2-weighted high intensity between muscles and in muscle belly; grade 2, injury of musculotendinous junction; and grade 3, rupture of tendon insertion.

Results

The sites of injuries were distributed as follows: hamstrings (n = 33), quadriceps (n = 6), hip adductors (n = 6), and calves (n = 10). MRI findings revealed 9 muscle strains (16%), 19 grade 1a (34%), 19 grade 1b (34%), and 8 grade 2 muscle strains (16%). The length of time until return to training and competition, respectively, was 15 and 26 days for grade 1a injuries, 19 and 36 days for grade 1b injuries, and 55 and 69 days for grade 2 injuries.

Conclusion

Players with grade 1 injuries took 4 to 5 weeks to return to play, whereas players with grade 2 injuries took 10 weeks to return. MRI can be useful for diagnosing lower extremity muscle strains and predicting the time to return to play.

Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players

BACKGROUND

Calf muscle strain injuries (CMSI) are prevalent in sport, but information about factors associated with time to return to play (RTP) and recurrence is limited.

PURPOSE

To determine whether clinical and magnetic resonance imaging (MRI) data are associated with RTP and recurrence after CMSI.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data of 149 CMSI reported to the Soft Tissue injury Registry of the Australian Football League were explored to evaluate the impact of clinical data and index injury MRI findings on RTP and recurrence. Clinical data included age, previous injury history, ethnicity, and the mechanism of injury.

RESULTS

Irrespective of the anatomical location, players with CMSI with severe aponeurotic disruption (AD) took longer to RTP than players with CMSI with no AD: 31.3 ± 12.6 days vs 19.4 ± 10.8 days (mean ± SD; P = .003). A running-related mechanism of injury was associated with a longer RTP period for CMSI overall (adjusted hazard ratio [AHR], 0.59; P = .02). The presence of AD was associated with a longer RTP period for soleus injuries (AHR, 0.6; P = .025). Early recurrence (ie, ≤2 months of the index injury) was associated with older age (AHR, 1.3; P = .001) and a history of ankle injury (AHR, 3.9; P = .032). Older age (AHR, 1.1; P = .013) and a history of CMSI (AHR, 6.7; P = .002) increased the risk of recurrence within 2 seasons. The index injury MRI findings were not associated with risk of recurrence.

CONCLUSION

A running-related mechanism of injury and the presence of AD on MRI were associated with a longer RTP period. Clinical rather than MRI data best indicate the risk of recurrent CMSI.

Sports-related lower limb muscle injuries: pattern recognition approach and MRI review

Muscle injuries of the lower limbs are currently the most common sport-related injuries, the impact of which is particularly significant in elite athletes. MRI is the imaging modality of choice in assessing acute muscle injuries and radiologists play a key role in the current scenario of multidisciplinary health care teams involved in the care of elite athletes with muscle injuries. Despite the frequency and clinical relevance of muscle injuries, there is still a lack of uniformity in the description, diagnosis, and classification of lesions. The characteristics of the connective tissues (distribution and thickness) differ among muscles, being of high variability in the lower limb. This variability is of great clinical importance in determining the prognosis of muscle injuries. Recently, three classification systems, the Munich consensus statement, the British Athletics Muscle Injury classification, and the FC Barcelona-Aspetar-Duke classification, have been proposed to assess the severity of muscle injuries. A protocolized approach to the evaluation of MRI findings is essential to accurately assess the severity of acute lesions and to evaluate the progression of reparative changes. Certain MRI findings which are seen during recovery may suggest muscle overload or adaptative changes and appear to be clinically useful for sport physicians and physiotherapists.

Correlating clinical assessment and MRI findings in diagnosing calf injuries in elite male Australian rules footballers

OBJECTIVE

Calf complex injuries represent a significant injury burden among Australian Rules athletes. To date, there has been limited research correlating clinical and radiological findings of pathology within the calf. The objective of this study is to determine how accurately magnetic resonance imaging (MRI) findings correlate with clinical measures of calf muscle complex pathology in elite male athletes.

MATERIALS AND METHODS

A prospective cohort study was conducted on Australian rules elite athletes. A cohort of 45 athletes underwent a high-load training session of approximately 10 km of running. Athletes were then assessed by a sports physiotherapist who made a diagnosis of no pathology, delayed onset muscle soreness, strain or other. Subsequently, the athletes underwent MRI of their bilateral calf complexes. Radiologists interpreted the MRI findings and radiological diagnosis were correlated with clinical diagnosis.

RESULTS

A total of 90 calf MRIs were performed. Correlation of clinical and radiological diagnosis occurred in 57 cases. Of the 33 cases which did not correlate, there were 4 radiologically significant acute calf strains in clinically asymptomatic athletes, 3 of which involved old scar tissue.

CONCLUSION

MRI may detect clinically insignificant injuries within the calf complex. If an athlete does not have any clinically relevant symptoms, abnormal signal on MRI may represent a different diagnosis to muscle strain. Signal change on MRI proximal to scar tissue may represent reactive oedema. Clinical history and examination should be correlated with radiological findings is recommended when diagnosing calf injury in elite athletes.

Calf muscle strain injuries in elite Australian Football players: A descriptive epidemiological evaluation

BACKGROUND

Calf muscle strain injuries (CMSI) show consistent rates of prevalence and re-injury in elite Australian Football players. An epidemiological evaluation is warranted to better understand the clinical presentation and recovery of CMSI.

PURPOSE

First, to describe the epidemiology of CMSI in elite Australian Football players. Second, to determine if recovery following injury is different according to: (a) injury type (index vs re-injury); (b) muscle injured (soleus vs gastrocnemius); and (c) mechanism of injury (running-related activity vs non running-related activity).

STUDY DESIGN

Descriptive epidemiological.

METHODS

Data retrieved from the Soft Tissue injury Registry of the Australian Football League were analyzed. Sixteen clubs submitted data on CMSI from 2014 to 2017. Data included: player characteristics, training and match history at the time of injury, MRI, and the time to reach recovery milestones.

RESULTS

One hundred and eighty-four CMSI were included (149 index injuries; 35 re-injuries). Soleus injuries were most prevalent (84.6%). Soleus injuries took 25.4 ± 16.2 days to return to play, whereas gastrocnemius injuries took 19.1 ± 14.1 days (P = .097). CMSI sustained during running-related activities took approximately 12 days longer to recover than injuries sustained during non running-related activities (P = .001). Compared to index injuries, re-injuries involved older players (P = .03) and significantly more time was taken to run at >90% of maximum speed, return to full training, and return to play (P ≤ .001). Almost all of the observed re-injuries involved soleus (91.4%).

CONCLUSION

Soleus injuries are more prevalent than gastrocnemius injuries in elite Australian Football players. Prognosis appears to be influenced by clinical factors, with CMSI sustained during running-related activities and re-injuries needing more time to recover.

Is It All About the Fascia? A Systematic Review and Meta-analysis of the Prevalence of Extramuscular Connective Tissue Lesions in Muscle Strain Injury

Background:

The fascia has been demonstrated to represent a potential force transmitter intimately connected to the underlying skeletal muscle. Sports-related soft tissue strains may therefore result in damage to both structures.

Purpose:

To elucidate the prevalence of connective tissue lesions in muscle strain injury and their potential impact on return-to-play (RTP) duration.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Imaging studies describing frequency, location, and extent of soft tissue lesions in lower limb muscle strain injuries were identified by 2 independent investigators. Weighted proportions (random effects) were pooled for the occurrence of (1) myofascial or fascial lesions, (2) myotendinous lesions, and (3) purely muscular lesions. Study quality was evaluated by means of an adapted Downs and Black checklist, which evaluates reporting, risk of bias, and external validity.

Results:

A total of 16 studies (fair to good methodological quality) were identified. Prevalence of strain injury on imaging studies was 32.1% (95% CI, 24.2%-40.4%) for myofascial lesions, 68.4% (95% CI, 59.6%-76.6%) for myotendinous lesions, and 12.7% (95% CI, 3.0%-27.7%) for isolated muscular lesions. Evidence regarding associations between fascial damage and RTP duration was mixed.

Conclusion:

Lesions of the collagenous connective tissue, namely the fascia and the tendinous junction, are highly prevalent in athletic muscle strain injuries. However, at present, their impact on RTP duration is unclear and requires further investigation.

Healing Process of Gastrocnemius Muscle Injury on Ultrasonography Using B-Mode Imaging, Power Doppler Imaging, and Shear Wave Elastography

OBJECTIVES

Muscle injury often occurs in sports activity. To avoid reinjury, it is important to determine the appropriate period until return to play after injury. The purpose of this study was to evaluate characteristics of the healing process for gastrocnemius muscle injury by B-mode imaging, power Doppler (PD) imaging, and shear wave elastography (SWE).

METHODS

Twenty patients with acute calf musculotendinous injury were enrolled. Scar thickness on B-mode imaging, new vessels according to PD grades, and SWE values in the muscle, musculotendinous junction, and tendon of the medial head of gastrocnemius were measured at 4, 8, and 12 weeks after injury.

RESULTS

Scar thickness was significantly larger at 8 and 12 weeks compared with 4 weeks (P < .01 for both). Power Doppler grades at 4 and 8 weeks were significantly higher compared with 12 weeks (P < .01 for both). Shear wave elastographic values in the muscle on the injury side were significantly higher at 8 and 12 weeks compared with 4 weeks (P < .01 for both), whereas those in the musculotendinous junction on the injury side were significantly higher at 12 weeks compared with 4 and 8 weeks (P < .01; P = .01, respectively).

CONCLUSIONS

B-mode imaging, PD imaging, and SWE can measure the healing process after musculotendinous injury of the gastrocnemius medial head.

Magnetic resonance imaging of muscle injury in elite American football players: Predictors for return to play and performance

Muscle injury accounts for about one-third of total sports-related injuries. The lower limb muscles have one of the highest predisposition for injury in high-level professional athletic sports, such as the National Football League. The commonest group of muscles injured among football players include the hamstrings, followed by the quadriceps. Muscle injuries lead to significant time, off the field and affect return to play. Sports physicians and teams have been keen on assessing such injuries and also relying on multiple tools to safely return the player back to the field. MRI plays a key role in evaluation, follow-up, and assessment for return to play (RTP). In this review, we will discuss details of muscle anatomy, incidence of muscle injuries, injury mechanisms, and use of MRI in assessment, grading, follow-up and in predicting the natural course of muscle injuries in the high-end athletic players. While the use of MRI is clear in diagnosis, and for follow up of muscle injuries, there is some limitation in its ability to predict RTP, based on current MRI classification systems. Footballers who have clinical injuries without MRI evidence of significant muscle injury (grade 0 and 1) have a shorter period of RTP. Injuries classified as high grade (3 and 4) on MRI do not correlate well with time to RTP. Further trials are required to improve the capability of MRI in its prediction of RTP.

Lower limb muscle injuries: The good, the bad and the ugly

Injuries to the lower limb muscles are a common cause of absence from training and competition in athletes. The different muscular groups of the thigh and leg are involved in various activities with kicking and sprinting being responsible for the largest number of injuries. The muscle acts on bone through the tendon and the fascia. The failure of one or more of these structures results in various degrees of loss of function of the muscle(s) involved. Usually, the point of weakness is the interface between different structures with different elastic properties (myofascial, myotendinous, avulsion). Diagnostic imaging is best performed by MRI that provides valuable information about the severity of the injury and its anatomical extent. In this article, we will review the MRI features of muscle injuries which can be used to guide return to play. We will emphasize the clinical implications of the MRI findings by dividing the muscle injuries into three categories "The Good, The Bad and The Ugly" to help the clinician in the planning of the most appropriate rehabilitation strategy.

Connective tissue injury in calf muscle tears and return to play: MRI correlation

Objective

The aim of our study was to assess a group of patients with calf muscle tears and evaluate the integrity of the connective tissue boundaries and interfaces. Further, we propose a novel MRI grading system based on integrity of the connective tissue and assess any correlation between the grading score and time to return to play. We have also reviewed the anatomy of the calf muscles.

Materials and methods

We retrospectively evaluated 100 consecutive patients with clinical suspicion and MRI confirmation of calf muscle injury. We evaluated each calf muscle tear with MRI for the particular muscle injured, location of injury within the muscle and integrity of the connective tissue structure at the interface. The muscle tears were graded 0–3 depending on the degree of muscle and connective tissue injury. The time to return to play for each patient and each injury was found from the injury records and respective sports doctors.

Results

In 100 patients, 114 injuries were detected. Connective tissue involvement was observed in 63 out of 100 patients and failure (grade 3 injury) in 18. Mean time to return to play with grade 0 injuries was 8 days, grade 1 tears was 17 days, grade 2 tears was 25 days and grade 3 tears was 48 days (p<0.001).

Conclusion

The integrity of the connective tissue can be used to estimate and guide the time to return to play in calf muscle tears.

Injuries in Australian Rules Football: An Overview of Injury Rates, Patterns, and Mechanisms Across All Levels of Play

CONTEXT

The nature of Australian rules football (Australian football) predisposes both unique and common injuries compared with those sustained in other football codes. The game involves a combination of tackling, kicking, high-speed running (more than other football codes), and jumping. Two decades of injury surveillance has identified common injuries at the professional level (Australian Football League [AFL]).

OBJECTIVE

To provide an overview of injuries in Australian rules football, including injury rates, patterns, and mechanisms across all levels of play.

STUDY DESIGN

A narrative review of AFL injuries, football injury epidemiology, and biomechanical and physiological attributes of relevant injuries.

RESULTS

The overall injury incidence in the 2015 season was 41.7 injuries per club per season, with a prevalence of 156.2 missed games per club per season. Lower limb injuries are most prevalent, with hamstring strains accounting for 19.1 missed games per club per season. Hamstring strains relate to the volume of high-speed running required in addition to at times having to collect the ball while running in a position of hip flexion and knee extension. Anterior cruciate ligament injuries are also prevalent and can result from contact and noncontact incidents. In the upper limb, shoulder sprains and dislocations account for 11.5 missed games per club per season and largely resulted from tackling and contact. Concussion is less common in AFL than other tackling sports but remains an important injury, which has notably become more prevalent in recent years, theorized to be due to a more conservative approach to management. Although there are less injury surveillance data for non-AFL players (women, community-level, children), many of these injuries appear to also be common across all levels of play.

CLINICAL RELEVANCE

An understanding of injury profiles and mechanisms in Australian football is crucial in identifying methods to reduce injury risk and prepare players for the demands of the game.