Four distinct patterns of anterior cruciate ligament injury in women's professional football (soccer): a systematic video analysis of 37 match injuries

BACKGROUND

To identify mechanisms and patterns of anterior cruciate ligament (ACL) injury in adult women's professional football by means of video match analysis.

METHODS

ACL match injuries sustained in Germany's first women's league during the 2016-2017 to 2022-2023 seasons were prospectively analysed by three expert raters using a standardised observation form. Epidemiological and injury data, as well as the medical history of ACL tears, were obtained from media reports and the statutory accident insurance for professional athletes.

RESULTS

Thirty-seven ACL injuries sustained in official football matches were included in the video analysis, of which 24 (65%) had associated knee injuries, mainly meniscus and collateral ligament injuries. According to the categorised contact mechanisms, 17 (46%) were non-contact injuries, 14 indirect contact injuries (38%) and six direct contact injuries (16%). Of the 17 non-contact injuries, seven (41%) occurred during the first 15 min of the match. Contact mechanisms did not differ between primary and secondary ACL injuries to the same or the contralateral side. Most injuries (80%) of field players occurred during horizontal movements such as sprinting (n=9, 26%), change-of-direction manoeuvres (n=7, 19%), stopping (n=5, 14%) and lunging (n=5, 14%). Four distinct repetitive patterns of ACL match injuries were identified: (1) non-contact 'pressing ACL injury' (n=9), (2) indirect contact 'parallel sprinting and tackling ACL injury' (n=7), (3) direct contact 'knee-to-knee ACL injury' (n=6) and (4) non-contact 'landing ACL injury' (n=4).

CONCLUSION

Most of the identified patterns of ACL injuries in women's professional football have great potential for prevention.

Heading and risk of injury situations for the head in professional German football: a video analysis of over 150,000 headers in 110,000 match minutes

To provide detailed epidemiological data on situations with a propensity of head injuries due to heading in professional football. In a prospective cohort study including the four highest professional football leagues in Germany, headers carried out in 1244 official matches and critical situations (CI) with a potential risk for injuries over one season were assessed by video analysis and a standardised video protocol. Results: 154,766 headers in 111,960 match minutes were recorded (1.4 headings/min). Video analysis showed a mean of 6.2 headers per field player and match (SD: 2,9; min: 0; max: 19) in the entire study population with a peak in the third league (7.1 per player and match). Headers were predominantly carried out with the forehead (78.5%), and nearly two-thirds occurred during defence (64.3%). 49.9% of all headers occurred during tackling, of which 78.3% involved body contact with an opponent. Video analysis yielded 848 CI. 74.5% of all critical incidents occurred during heading duels as a part of tackling (odds ratio: 3.6, 95%-CI: 2.4-5.2), and 99.4% involved body contact (odds ratio: 5.9, 95%-CI: 2,8-12,7). This study is the first to provide detailed epidemiological data on heading and critical incidences with high risk for head injuries in professional football. Heading duels bear a high risk of head injury and thus represent a key target for prevention strategies. The impacts of headers should be critically investigated regarding neurological consequences in further studies, by including the mean heading rate per mal field player and match.

Training matters: Heading incidence and characteristics in children's and youth football (soccer) players

OBJECTIVE

Concerns about short- and long-term consequences of repetitive heading contributed to heading restrictions in youth football in some countries. This prospective longitudinal cohort study aims to describe heading exposure in children's and youth football over two seasons using standardized video analysis.

METHODS

All matches and training sessions of a male Under-11 (n = 29), Under-15 (n = 28), Under-19 (n = 38), and female Under-17 (n = 39) team were videotaped during the seasons 2019-2020 and 2020-2021. Heading frequencies and characteristics were analyzed. Individual heading exposure is presented as average incidence rates (IR) per 1000 match/training hours.

RESULTS

In 275 matches and 673 training sessions, 22 921 headers were observed. Heading IR per player in matches was 1256 (Under-11 m), 1608 (Under-15 m), 1050 (Under-17 f), and 1966 (Under-19 m). In training sessions, IR per player was 739 (Under-11 m), 2206 (Under-15 m), 1661 (Under-17 f), and 1419 (Under-19 m). Five Under-15 males headed the ball five to eight times per training on average. Most headers were performed without heading duels. Flight distance was predominantly 5-20 m (54%) in matches and <5 m (65%) in training. While head impact location most frequently was at frontal areas, one-third of all headers in Under-11 in matches hit temporal, parietal, and occipital parts of the head.

CONCLUSION

Heading incidence was low in the youngest age group, whereas (predominantly five) Under-15 males showed very high heading exposures in training. In assessment and regulation of heading burden, training sessions and individual heading behavior should specifically be addressed. Recommendations for heading the ball in practice should account for individual and age-related differences.

Contact times in professional football before and during the SARS-CoV-2 pandemic: Tracking data from the German Bundesliga

The global SARS-CoV-2 pandemic led to a lockdown in team sports in March 2020. Because the risk of virus transmission seems to correlate with the duration of close contacts, data on contact times are necessary to assess the risk of virus transmission in sports. In this study, an optical tracking system was used to determine contact times between players of the two highest men's professional football leagues in Germany in the 2019-20 season and in the first half of the 2020-21 season. Contacts between players were defined as being within a two-metre radius during matches and were differentiated as either match-specific or non-match-specific. In total, 918 matches with 197,087 contacts were analysed. The mean overall contact time of one-to-one situations of 36 s (SD: ± 66) before the lockdown was reduced to 30 s after the lockdown (SD: ± 60) (p < 0.0001). In professional football, contacts between two players infrequently occur within a two-metre radius, averaging less than 35 s. Only 36 player pair contacts lasted for more than 15 min (0.00018%). The mean accumulated contact time per player with all others was 10.6 ± 6.9 min per match, with a decrease from 11.6 ± 7.0 min before the lockdown to 10.0 ± 6.6 min (p < 0.0001) after lockdown in the season 2019-20. The SARS-CoV-2 pandemic has resulted in a reduction in match-specific contacts of 25%. It seems questionable if such short contacts in open-air sports may lead to considerable virus transmission.

Video analysis of 100 matches in male semi-professional football reveals a heading rate of 5.7 headings per field player and match

INTRODUCTION

Heading is an integral part of football and frequent media reports and previous studies about potential danger of heading and head trauma in football fuelled discussions. Epidemiological data and video analyses regarding headings situation and associated head injuries are still missing in male adult professional football.

METHODS

In a prospective cohort study in the male fourth German football league, 100 official matches of the 2015-2016 season were assessed by video analysis and a standardized protocol. Heading situations and concomitant circumstances as well as incidents with a propensity of injury (critical incidents) were analyzed. Critical incidents (CI) and seasonal reported head injuries were cross-referenced.

RESULTS

Overall, 11,514 headings were analysed in detail. Video analysis yielded a mean of 5.7 headings per player and match (SD: 1.2; range 0-15). Heading was predominantly performed with the frontal part of the head (76.8%), and nearly two thirds of all headings occurred during defending (65.8%). 71.0% of all headings occured during tacklings, of which 71.9% involved body contact with the opponent player. Video analysis yielded 31 CI on the head due to heading (incidence: 1.02 per 1000 h match exposure and player). 29 CI occurred during heading duels (odds ratio: 5.91), 30 CI with body contact (odds ratio: 28.8) and 6 CI with elbow contact (odds ratio: 6.13).

CONCLUSION

Heading frequency in male semi-professional football could be determined with a rate of 5.7 headings per match and field player. Cross referencing CI and seasonal reported head injuries revealed a very low number of reported head injuries.

No increased injury incidence in the German Bundesliga after the SARS-CoV-2 virus lockdown

INTRODUCTION

The coronavirus lockdown in 2020 resulted in a worldwide suspension of professional sports. The first major professional football league to restart after the lockdown was the German Bundesliga. This study investigates whether the injury incidence increased after the restart of the season with only 9 days of regular preparation time and without any friendly matches in comparison to three control periods.

MATERIALS AND METHODS

In a prospective cohort study, injury analysis (at least 1 day of absence from official football matches or training sessions) of the German Bundesliga registry was standardised according to Hägglund et al. (Br J Sports Med 39:340-346, 2005) and Fuller et al. (Clin J Sports Med 16:97-106, 2006) for data collection and to previous publications for the validated use of media sources for injury registration. The study period after the lockdown in May and June of the 2019-2020 season was compared to three control periods: the period directly before the lockdown, the beginning of the 2019-2020 season and the 2018-2019 season final.

RESULTS

The nine match days after the restart of the 2019-2020 season showed an overall injury incidence of 4.9 per 1000 h football. This rate was significantly lower than that of the previous season final (9 last match days, overall injury incidence: 6.9 per 1000 h football; p < 0.001) and not increased compared to the rates after the summer break (9 match days; incidence: 5.5/1000 h, p > 0.05) or the winter break (8 match days; incidence: 5.6/1000 h, p > 0.05).

CONCLUSION

The period after the unexpected break in the 2019-2020 season due to the coronavirus lockdown and the rapid return to competition showed no increase in the injury rate compared to the pre-lockdown period and a lower injury rate than in the previous season final. The unintentional mid-season rest with its potential for physical recovery and individual fitness training seems to have had a positive effect on injury occurrence.

Current Standards of Early Rehabilitation after Anterior Cruciate Ligament Reconstruction in German Speaking Countries-Differentiation Based on Tendon Graft and Concomitant Injuries

Background: Although anterior cruciate ligament reconstruction (ACLR) is a well-established procedure and is standardly performed by orthopedic surgeons all over the world, there does not seem to be a standard protocol for early rehabilitation. The purpose of this study was to give answers to the following questions: (i) Does (a) the use of a specific tendon graft, and (b) potentially additional therapy of concomitant pathologies influence surgeons’ choice of a distinct postoperative rehabilitation protocol after ACLR? (ii) To what extent do these rehabilitation recommendations differ? Methods: Retrospective analysis of currently used early rehabilitation protocols after ACLR in German-speaking countries (GER, AUT and SUI) was conducted. Rehabilitation criteria included weight bearing, range of motion (ROM), the utilization of braces, continuous passive/active motion therapy (CPM/CAM), rehabilitation training and sport-specific training. Tendon grafts were differentiated as hamstring (HAM) and bone−patellar tendon−bone grafts (BTB). Concomitant pathologies included meniscus injuries (+M) and unhappy triad injuries (+UTI). Results: Most of the surveyed protocols were differentiated according to the used tendon graft or additional therapy of concomitant injuries (ACLR-differentiated, n = 147 vs. ACLR without graft differentiation, n = 58). When comparing ACLR-HAM and ACLR-BTB, significant differences were found regarding weight bearing (p = 0.01), ROM (p = 0.05) and the utilization of braces (p = 0.03). Regarding ACLR+M, an overall significant decelerated rehabilitation could be detected. After ACLR+UTI-therapy, a significant delayed start to full weight bearing (p = 0.002) and ROM (p < 0.001) was found. Conclusions: Most orthopedic surgeons from German-speaking countries differentiate early rehabilitation after ACLR according to the tendon graft used and therapy of concomitant pathologies. No consensus about early rehabilitation after ACLR is available. However, tendencies for an accelerated rehabilitation after ACLR-BTB and a more restrained rehabilitation of multiple injured knees were detected.

Multicomponent stretching and rubber band strengthening exercises do not reduce overuse shoulder injuries: a cluster randomised controlled trial with 579 handball athletes

Objectives

Handball is associated with a high risk of overuse shoulder injury. This study investigated if an injury prevention programme effectively reduces overuse injury to the throwing shoulder of handball athletes.

Methods

61 men’s and women’s handball teams (u-19 and senior athletes) were cluster-randomised into an intervention and a control group in the 2019–2020 season. Players of the intervention group regularly carried out an injury prevention programme. Both groups documented overuse shoulder injuries via an online questionnaire every second week. The primary endpoint was the prevalence of overuse injury to the throwing shoulder. Secondary endpoints were the influence of compliance on the primary endpoint and intensity of overuse shoulder symptoms measured by a shortened, handball-specific Western Ontario Shoulder Index (WOSI).

Results

31 teams (295 players) in the intervention group and 30 teams (284 players) in the control group were included for analyses. The overall questionnaire response rate was 61%. The average prevalence of overuse shoulder injury did not significantly differ between the intervention group (n=109, 38.4% (95% CI 32.9% to 44.2%)) and the control group (n=106, 35.9% (95% CI 30.7% to 41.6%), p=0.542). Compliance with the intervention programme did not significantly affect overuse shoulder injury (p=0.893). Using generalised estimating equations for WOSI, the estimated mean for the intervention group was 44.6 points (95% CI 42.0 to 47.1) and 47.6 points for the control group (95% CI 44.9 to 50.3, p=0.111).

Conclusions

A multicomponent exercise programme using rubber bands and stretching did not significantly reduce the prevalence or symptoms of overuse throwing shoulder injury in handball athletes of both sexes. Randomised controlled study; level of evidence I.

Trial registration number

ISRCTN99023492.

Mental stress reduces performance and changes musculoskeletal loading in football-related movements

Purpose: Football players have a high risk of leg muscle injuries, especially when exposed to mental stress. Hence, this study investigated the musculoskeletal response of elite youth football players during highly dynamic movements under stress. The hypothesis is that mental stress reduces performance and changes the muscular forces exerted.Materials & methods: Twelve elite youth football players were subjected to mental stress while performing sports-specific change-of-direction movements. A modified version of the d2 attention test was used as stressor. The kinetics are computed using inverse dynamics. Running times and exerted forces of injury-prone muscles were analysed.Results: The stressor runs were rated more mentally demanding by the players (p = 0.006, r_s = 0.37) with unchanged physical demand (p = 0.777, r_s = 0.45). This resulted in 10% longer running times under stress (p < 0.001, d = -1.62). The musculoskeletal analysis revealed higher peak muscle forces under mental stress for some players but not for others.Discussion: The study shows that motion capture combined with musculoskeletal computation is suitable to analyse the effects of stress on athletes in highly dynamic movements. For the first time in football medicine, our data quantifies an association between mental stress with reduced football players' performance and changes in muscle force.

Higher risk of ACL rupture in amateur football compared to professional football: 5-year results of the 'Anterior cruciate ligament-registry in German football'

PURPOSE

Anterior cruciate ligament (ACL) injuries are a common severe type of football injury at all levels of play. A football-specific ACL registry providing both prospective ACL injury data according to the skill level and risk factors for ACL injury is lacking in the literature.

METHODS

This study is based on the prospective 'ACL registry in German Football' implemented in the 2014-15 season. Professional (1st-3rd league), semi-professional (4th-6th league) and amateur leagues (7th league) were analysed regarding the incidence and risk factors for ACL injuries. Injuries were registered according to the direct reports of the injured players to the study office and double-checked via media analysis. After injury registration, the players received a standardised questionnaire. Data were analysed from the 2014-15 to the 2018-19 football season.

RESULTS

Overall, 958 ACL injuries were registered during the 5-year study period. The incidence of ACL injuries was highest in amateur football (0.074/1000 h football exposure) compared to professional (0.058/1000 h; p < 0.0001) and semi-professional football (0.043/1000 h; p < 0.0001). At all skill levels, match incidence (professional: 0.343; semi-professional: 0.249; amateur: 0.319) was significantly higher than training incidence (professional: 0.015; semi-professional: 0.004; amateur: 0.005). Major risk factors were previous ACL injury (mean: 23.3%), other knee injuries (mean: 19.3%) and move to a higher league (mean: 24.2%).

CONCLUSION

This sports-specific ACL registry provides detailed information on the incidence and risk factors for ACL injuries in football over five years. Risk factors are skill level, match exposure, move to a higher league and previous knee injury. These factors offer potential starting points for screening at-risk players and applying targeted prevention.

LEVEL OF EVIDENCE

II.

Increased occurrence of ACL injuries for football players in teams changing coach and for players going to a higher division

PURPOSE

To identify football-specific factors associated with ACL injuries that can be targeted for sport-specific injury prevention.

METHODS

A study-specific questionnaire was developed to study the characteristics of ACL injuries in football including intrinsic, extrinsic, and injury specific factors. The questionnaire was available at the Swedish national knee ligament registry's website for the football players to voluntarily fill out. Data are presented on group level for all football players in total and for females and males separate to examine gender-specific differences. The results are based on answers collected over a 3-year period from 2875 football players, 1762 (61%) males and 1113 (39%) females.

RESULTS

ACL were more frequently sustained during games 66% than during practices 25%. The injury mechanism was non-contact in 59% and contact in 41%. For the contact injuries during games, no action was taken by the referee in 63% of the situation and a red card was shown in 0.5%. The risk of ACL injury was highest early in the football game with 47% sustained during the first 30 min and 24% in the first 15 min. Players changing to a higher level of play 15% had a higher rate of ACL injuries than players changing to a lower level 8%. This difference was especially seen in female football players with 20% of ACL injuries being sustained by players going to a higher division compared to 7% for those going to a lower division. 15% of the male and 21% of the female ACL injuries occurred in teams with a coach change during the season. Knee control exercises to warm up was used by 31% of the female players and 16% of the males. 40% of the players reported that they did not plan on returning to football.

CONCLUSION

Neuromuscular training programs have proven to reduce ACL injuries, but greater adherence to these remains a challenge as only 1 in 5 of the ACL-injured football players report using them. Teams changing coach and players going to a higher division appear to have an increased risk of ACL injury warranting attention and further investigations.

LEVEL OF EVIDENCE

IV.

High injury rates and weak injury prevention strategies in football referees at all levels of play

Football referees need other physiological requirements on field than football players and are affected by different types of injury. The absence of referees may result in canceled matches, so special focus should be placed on injury prevention through specific training programs for referees. This study retrospectively analyzed injury occurrence and prevention strategies for German football referees at the different levels of play over one season. Data were collected by means of seasonal injury reports based on the consensus statement of injury definition and data collection. Of the 923 participating referees, 91 (9.9%) played at the professional level, 151 (16.3%) at the semi-professional, and 681 (73.8%) at the amateur level. 86.2% (n = 796) were men and 13.8% (n = 127) women. Referees at the amateur level showed the highest injury incidence (3.14/1000 h football) compared to referees at the semi-professional (1.92/1000 h; p < 0.001) and professional level (1.01/1000 h; p < 0.001). Most referees at the amateur (n = 372; 56.4%) and semi-professional level (n = 46; 31.3%) conducted warm-up programs of <10 min, whereas the mean warm-up duration of professional referees was >11 min (n = 75; 82.4%). Although running and stretching exercises were common among referees during warm-up, preventive exercises focusing on coordination and trunk muscles were less frequent, especially among amateur referees (jumping: 15.9%; strengthening: 9.7%; balance exercises: 7.9%). Injury incidence was highest at lower amateur levels, which thus has specific need for injury prevention. Appropriate training exercises to prevent injuries of referees were weak at all levels of play, especially the lack of strength, plyometric, and balance exercises in training and warm-up programs.

The Incidence of Fractures Among the Adult Population of Germany – and Analysis From 2009 through 2019

BACKGROUND

Detailed analyses of epidemiological data on fractures are an important resource for persons and institutions providing health care services, as they yield information on the effects of current treatment strategies and on the need for preventive measures. The epidemiology of fractures in Germany, however, is unknown. The goal of this study is to determine the nationwide fracture burden from 2009 through 2019, as a function of anatomical site, age, and sex.

METHODS

Annual compilations of ICD-10 diagnosis codes for the years 2009-2019 were made available to us by the German Federal Statistical Office. The prevalence and incidence of fractures at 30 different sites were quantified, and standardized sex and age distributions were calculated.

RESULTS

A total of 688 403 fractures was registered in 2019. From 2009 to 2019, the incidence of fractures rose by 14%, to 1014 fractures per 100 000 persons per year. The most common fracture types were femoral neck fractures (120 per 100 000 persons per year), pertrochanteric femural fractures (109 per 100 000 persons per year), and distal radius fractures (106 per 100 000 persons per year). All types were more common in women, with incidences that rose with age. The highest incidence was of pertrochanteric femoral fractures in women over age 90, with an incidence of 2550 per 100 000 persons per year. The largest rises in incidence were seen with regard to acetabular fractures (+ 58.16%) and clavicular fractures (+ 44.02%).

CONCLUSION

The increasing frequency of fractures, particularly among the elderly, presents a challenge to the health care system. Given the high frequency of geriatric fractures, prophylactic measures against fractures ought to be intensified.

Head injuries in professional football (soccer): Results of video analysis verified by an accident insurance registry

BACKGROUND

Video analysis is one of the most commonly applied methods for analysing football injuries.

PURPOSE

The objective of this study was to assess the accuracy of video analysis for recording head injuries in professional football from official matches in the four highest men's professional football leagues in Germany.

METHODS

In this cohort study, head injuries detected by means of video analysis of all official matches over one season (2017-18) were compared to head injuries registered with the German statutory accident insurance.

RESULTS

Our video analysis yielded 359 head injuries of 287 players. The comparison of head injuries found in our video analysis to those registered with the accident insurance only yielded a match in 23.1% (n = 83), which presents a rather low verification rate. The verification rates varied between the leagues (7.0-30.8%). All injuries documented in the accident insurance registry were found in the video analysis (100%). The types of head injury most often verified by the accident insurance registry (n = 83) were contusion (43.4%), bone fractures (19.3%) and skin lacerations (18.1%). Only 66 of the 359 head injuries (18.4%) resulted in absence from at least one training session and involved a mean time loss of 18.5 days (1-87 days).

CONCLUSION

The mismatch between the number of head injuries found in the video analysis and head injuries registered with the accident insurance is an important methodological issue in scientific research. The low verification rate seems to be due to the unclear correlation between injury severity and clinical consequences of head injuries detected by means of video analysis and the failure of football clubs to register minor head injuries with the accident insurance.

Injury Epidemiology of 626 Athletes in Surfing, Wind Surfing and Kite Surfing

Introduction/Background

Surfing, wind surfing and kite surfing enjoy a growing popularity with a large number of athletes worldwide. The aim of this study was to identify and compare the injury profiles and compare the injury profiles of these three extreme water sports.

Materials and Methods

These data for this retrospective cohort study were collected through an online standardised questionnaire during the 2017–18 season. The questionnaire included questions about anthropometry, skill level, injury diagnosis, injury mechanism, environmental conditions and training regimes.

Results

The 626 athletes included reported 2584 injuries. On average, each athlete sustained 4.12 injuries during the season. The most frequent injury location was in the lower extremity, in particular the foot, with 49 (16.4%) injuries in surfing, 344 (18.3%) in wind surfing and 79 (19.7%) in kite surfing. Surfing demonstrated a particularly high rate of head injuries (n = 37; 12.4%). Other frequent injury types were skin lesions (up to 42.1%) and contusions (up to 40.5%). The most common injury across all surfing sports was skin lesions of the foot (wind surfing: 11.7%; kite surfing: 13.2%; surfing: 12.7%). In surfing, skin lesions of the head were frequently observed (n = 24; 8.0%). In surfing, a ‘too large wave’ (n = 18; 24.7%) was main cause of the injury, while in wind surfing (n = 189; 34.5%) and kite surfing (n = 65; 36.7%) ‘own incompetence’ led to the most injuries.

Conclusion

This unique study compares injury epidemiology and mechanism in the three most popular surfing sports: wind surfing, kite surfing and surfing. Overall, injuries were sustained mainly in the lower extremity, while surfing also demonstrated a high rate of head injuries.

[Extended medical preparticipation screening as a useful option for injury prevention in professional sports]

BACKGROUND

 Preparticipation screening is important in order to make a statement about an athlete's health. The evaluation includes both an internal medicine/cardiology and an orthopaedic section. In professional team sports, players have to undergo medical screening on an annual basis to obtain their license and be cleared for play. Screening delivers information about the acute health condition of the athlete but only gives an indirect statement on his/her functional status and performance. This gap has been tried to be closed with functional, sports-specific performance testing in the past few years. In the event of future injury, the collected data can be used as a baseline level to monitor the progress in an athlete's rehabilitation process. This provides a huge advantage in the return-to-play diagnosis.

MATERIAL & METHODS

 Based on the assumption that only a healthy player can perform to the best of his or her ability, we have extended our medical screening for a professional basketball team. Since the 2012/2013 season, a test battery was added with a view to basketball-specific conditioning. The collected data was prospectively correlated to injury occurrence.

RESULTS

 Seventy-one players were tested in 5 different categories. We have documented 142 injuries which lead to a downtime of 23 days (range 1-347 days). The injuries mainly involved the lower extremity, in particular the ankle, the knee and the thigh muscles. There was a clear trend indicating that players performing weaker in the agility tests sustained more injuries (r = 0.34, p = 0.029). Athletes who performed worse in the Yo-Yo test suffered from significantly more thigh muscle injuries (r = 0.266, p = 0.012).

CONCLUSION

 Pre-participation screening is a useful tool in injury prevention, which helps to detect injuries or chronic stress complaints, especially in, but not limited to professional sports. Adding sports-specific performance testing may reveal potential deficits in agility and endurance which could lead to an increased injury risk. In addition, it allows to obtain baseline data which could be used to show the progress in rehabilitation in the event of an injury.

Results of a tri-national online survey on the current status of sports injury prevention among members of the German-Speaking Orthopaedic Sports Medicine Society (GOTS)

OBJECTIVES

 To assess the current opinions and state of knowledge in primary sports injury prevention among members of the German-Speaking Society for Orthopaedic and Traumatologic Sports Medicine (GOTS).

METHODS

 On 21 August 2019, a web-based questionnaire was sent to the members of the tri-national society GOTS (Austria, Germany and Switzerland). The survey was online until 21 November 2019 and included twenty-two questions, which were divided into five sections: 1) general importance of prevention (n = 4), 2) specifications of the study population (n = 3), 3) implementation of prevention (n = 8), 4) improvement opportunities in prevention (n = 4) and 5) future research areas (n = 3).

RESULTS

 A total of 272 participants completed the survey, representing a total survey participation of 17.7 % of all members. The study population consisted of orthopaedic surgeons (55 % with surgical and 21 % with non-operative orientation), medical students (10 %), physical therapists (8 %) and sports scientists (4 %). Ninety-four percent of all participants stated that they considered the importance of sports injury prevention to be "very high" (68 %) or "high" (26 %). However, almost 70 % of all participants stated that they spend less than one hour per week on injury prevention work. The term "prevention" was clearly defined and practicable for only 40 %, understandable but difficult to implement for 51 %, and unclear and difficult to implement for 9 % of the participants. Seventy-two percent of respondents were aware of existing prevention programs such as "Stop-X" or "FIFA 11 +", whereas 28 % of participants were uninformed regarding these programs.

CONCLUSIONS

 A strong divergence was identified between participants' perception of the importance of sports injury prevention and the existing implementation of preventive measures. Future funding of prevention programs, expansion of research strategies for injury prevention and better financial reimbursement are of utmost importance.

Prevalence of SARS-CoV-2 IgG antibodies in a large prospective cohort study of elite football players in Germany (May-June 2020): implications for a testing protocol in asymptomatic individuals and estimation of the rate of undetected cases

OBJECTIVES

Elite professional football players and staff are a unique group that might give insight into the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Germany and thus can serve as a model for geographical distribution and an estimation of undetected infections.

METHODS

In this prospective cohort study seroprevalence was determined twice in May and June 2020 in players and staff from the German Bundesliga. As screening assays, a commercial ELISA (Euroimmun) and a chemiluminescent immunoassay (CLIA) (Roche) were used, and an in-house neutralization assay (NT) was used as reference standard. Participants were tested twice weekly using PCR from nasopharyngeal and/or oropharyngeal swabs.

RESULTS

Seroprevalence (NT used as confirmation) in 2164 samples from 1184 players and staff was rather similar in May (23/1157, 1.99%) and June (21/1007, 2.09%). All participants were PCR-negative during the study period. Significant regional differences in seroprevalence were not observed. When comparing seroprevalence with the cumulative incidence of infections derived from the German notification system (subgroup matching to cohort; men, age 20-69 years), IgG was found eight to ten times more frequently, pointing to a high rate of undetected infection. ELISA and CLIA correlated only moderately (κ 0.52).

CONCLUSIONS

Seroprevalence with a high-quality diagnostic in Germany seemed to be around 2%. The number of undetected infections seems to be eight to ten times higher than in notification data. The quality of antibody assays is rather variable, thus results should ideally be confirmed at least by a second assay to prove IgG positivity.

Early functional treatment or trivialization? - current treatment strategies in lateral ligament injuries of the ankle

Introduction: Ankle injuries are common in daily orthopaedic trauma practice, with a high incidence of lateral ligament complex (lat-lig-com) injuries of the ankle joint (AJ). Primarily, these lat-lig-com injuries heal sufficiently, although there is a risk of developing chronic ankle instability. However, there is a lack of knowledge about the clinical application and routine for rehabilitation strategies so as to prevent chronic instability. This study investigates the current rehabilitation concepts in clinical routine after ligament injuries of the AJ. Methods: Rehabilitation protocols, provided by orthopaedic and trauma surgery institutions in German speaking countries, were analysed in terms of weight-bearing, range of motion (ROM), physiotherapy and choice of orthosis. All protocols for operatively and non-operatively (nop) treated ligament ruptures of the AJ were included. Results: 120 of 213 institutions provided protocols of lat-lig-com injuries of the AJ. Regarding the orthosis, the nop-treatment group mainly used ankle braces; in contrast, the operative group preferred the use of an ankle boot. The operative group recommends 6-12 weeks for duration of orthosis in contrast to only 6 weeks in the nop group. Significant differences prevail in ROM, with free ROM in non-operative treatment from the first day after trauma (p<0.001) in contrast to a careful increase in ROM in the first 6 weeks post-operatively. Conclusion: Early functional treatment is clinical standard in rehabilitation after lat-lig-com injuries of the ankle. Regarding current literature the differences of restrictions in ROM and orthosis treatment after lat-lig-com injuries suggest a trivialization of conservative treatment in the first period after trauma compared to post-operative aftercare.

Injury epidemiology in men's professional team sports: is media analysis helpful?

INTRODUCTION

Epidemiological injury surveillance in professional sports is often based on online media analysis in order to collect necessary data. However, the validation of this study protocol is lacking. Therefore, this study aimed to identify the validity of injury surveillance in men's professional team sports based on media reports.

METHODS

In a retrospective cohort study, the validity of media-data-relating injuries was investigated in participating teams of the highest two German divisions in men's professional basketball (BB) and handball (HB) in the season 2018/2019. Injury protocols completed by the team physicians were compared to those of sports media injury reports.

RESULTS

The study population was composed of 133 athletes (54 BB and 79 HB). Of 343 injuries reported by the team physicians, 151 (44%) could be identified by means of sports media reports. Severe injuries (n = 75, 72%) were reported more likely in sports media compared to less severe injuries (n = 76, 32%, p < 0.00001). Odds ratio (OR) was 5.33 (95% CI 3.22-8.82). No differences regarding injury reporting could be seen between the two team sports.

CONCLUSION

For severe injuries, media analysis may be a sufficient method for data collection in popular men's professional ball sports. An underestimation of true injury prevalence lies within the range of previous reported investigations concerning the validation of injury surveillance methods. Non-severe injuries could not be verified via media analysis in professional handball and basketball.

Successful return to professional men's football (soccer) competition after the COVID-19 shutdown: a cohort study in the German Bundesliga

OBJECTIVES

To evaluate the restart of the German Bundesliga (football (soccer)) during the COVID-19 pandemic from a medical perspective.

METHODS

Participants were male professional football players from the two highest German leagues and the officials working closely with them. Our report covers nine match days spread over 9 weeks (May to July 2020). Daily symptom monitoring, PCR testing for SARS-CoV-2 RNA twice weekly, and antibody tests (on two occasions-early during the phase in May 2020 and in the week of the last match) were conducted. Target variables were: (1) onset of typical COVID-19 symptoms, (2) positive PCR results, and (3) IgG seroconversion against SARS-CoV-2. All detected seroconversions were controlled by neutralisation tests.

FINDINGS

Suspicious symptoms were reported for one player; an immediate additional PCR test as well as all subsequent diagnostic and antibody tests proved negative for coronavirus. Of 1702 regularly tested individuals (1079 players, 623 officials members), 8 players and 4 officials tested positive during one of the first rounds of PCR testing prior to the onset of team training, 2 players during the third round. No further positive results occurred during the remainder of the season. 694 players and 291 officials provided two serum samples for antibody testing. Nine players converted from negative/borderline to positive (without symptoms); two players who initially tested positive tested negative at the end of the season. 22 players remained seropositive throughout the season. None of the seroconversions was confirmed in the neutralisation test.

CONCLUSION

Professional football training and matches can be carried out safely during the COVID-19 pandemic. This requires strict hygiene measures including regular PCR testing.

Z-score values of left ventricular dimensions in adolescent elite male soccer players

Recent studies showed contrasting findings in morphological changes due to competitive soccer in adolescent players (SP). We present a prospective study in 315 consecutive adolescent (10-14 years) male elite SP and 53 healthy matched active controls (CON). All participants underwent a complete transthoracic two-dimensional echocardiography (TTE). The mean age in SP was 12.8 ± 0.65 years compared to 12.6 ± 0.8 years in CON. For all left ventricular (LV) dimensions, mean Z-score values were higher in SP. There was a significant Z-score increase in interventricular septum diastolic diameter (2.47z vs. 1.62z, p < 0.05), left ventricular posterior wall diastolic and systolic diameter (1.15z vs. 0.47z, p < 0.05 and 1.05z vs. - 0.4z, p < 0.05). Athletes had significant greater LV mass indexed for BSA (94 ± 12 g/m² vs. 81 ± 13 g/m², p < 0.05). There was no significant difference in LV function or diameters. Conclusion: Our findings suggest that elite soccer training in adolescent male is a type of sport predominantly related to cardiac resistance remodeling. Adolescent SP may develop supernormal left ventricular wall dimensions (+ 2.0 to + 2.5z). If in SP Z-scores, any LV dimension above + 2.5 is measured, primary or secondary cardiomyopathies should be excluded. What is Known: • Morphological cardiac adaptation in response to exercise depends on the type, duration, and intensity of training. • Morphological and functional changes due to competitive sports (athlete's heart) occur even in pre-adolescent athletes. What is New: • Our findings point out that German elite soccer training in adolescent male (10-14 years of age) is a type of sport predominantly related to cardiac resistance remodeling. • If in an adolescent competitive soccer player any LV dimension Z-score value above + 2.5 is measured, a primary or secondary cardiomyopathy should be excluded.

Football-related injuries are the major reason for the career end of professional male football players

PURPOSE

Little is known about the consequences of injuries on professional male football players' career and retirement period. The aim of this study is to investigate the impact of injuries that male professional football players endure during their career, reasons for the end of their career and the post-career phase of retirement.

METHODS

In a retrospective cross-sectional cohort study, retired male professional football players of the German Bundesliga were investigated by a standardised questionnaire to analyse the history of injuries sustained during their professional football career, the reasons for ending their career, their current health status and their suggestions for future prevention strategies.

RESULTS

Most of the 116 analysed players (n = 73 (62.9%)) stated an injury as the reason for ending their professional career. Relevant injuries were mainly located in the lower extremities (n = 587 (61.3%)) with a focus on the knee (p < 0.001) and ankle (p < 0.001). A significant majority of the participants who had retired due to injury described degenerative symptoms, such as pain or instability, and were diagnosed with osteoarthritis after retirement (p < 0.001). These players had also often been affected by symptoms of depression during their career, which had decreased significantly after retirement. Moreover, players who had not retired due to injury had significantly better overall health status and quality of life after retirement.

CONCLUSION

Football-related injuries have a significant impact on the career end of professional male football players and their health status after retirement. Future prevention strategies need to particularly address injuries to the knees and ankles and to implement measures for preventing osteoarthritis after retirement.

LEVEL OF EVIDENCE

Level III.

Injury Profile and Sex-Specific Differences in Bubble-Soccer - A First Scientific Survey of a Dangerous New Sports Trend

Purpose

Small-field soccer is a popular type of amateur sports worldwide. One type of small-field soccer growing in popularity is bubble-soccer, but injury risks and injury patterns are still unclear. This study investigates the factors influencing injuries in bubble-soccer for the first time.

Materials and Methods

This prospective cohort study of an outdoor tournament investigated the injury incidence and injury patterns as well as the factors influencing injuries in bubble-soccer matches. Data were collected according to the statement on data collection and injury definition. Preparation and physical outcome were assessed for both sexes.

Results

Of 145 players (104 men, 41 women), 58 players sustained 94 injuries during the tournament and 64% of injuries affected the lower extremities. The most common traumatic injuries were skin lesions (37.5%), acute pain (15.6%) and contusion (7.8%). More female players (3818.2/1000 h bubble-soccer) than male players (1474.4) were affected by injury, mostly to the knees or the head. Also, women significantly more often reported neck pain than men (p<0.042); 29.0% of players felt uncomfortable wearing the bubble, and 21.4% reported neurological symptoms such as headache or dizziness after the match.

Conclusion

Bubble-soccer shows a relatively high injury incidence. Women had a higher injury incidence and were more often affected by traumatic injuries to the head and neck including feeling of discomfort and headache or neck pain after the match. Adequate preparation seems to be essential for injury prevention, and players should recognise the high injury risk of bubble-soccer.

Injury Analysis in Professional Soccer by Means of Media Reports - Only Severe Injury Types Show High Validity

Purpose

Injury data of professional soccer players obtained from media reports are frequently used in scientific research, but the accuracy of such data is still unclear.

Patients and Methods

Injuries of professional soccer players of the German first and second league were documented by continuously screening media reports over one season (2015-2016). After the season, the validity of media-reported injuries was anonymously analyzed by the team physicians of 8 different soccer clubs.

Results

A total of 255 injuries of 240 players of 8 professional soccer teams had been published online, of which 146 were confirmed by the team doctors as correct, yielding a rate of 57.3% of confirmed media-reported injuries. In addition, 92 injuries without media registration were detected and added to the online statistics, resulting in 347 injuries and an overall weak validity of media-based data of 42.1%. Statistical analysis showed that the validity of media-reported injury data depended on both the individual soccer club and the body site affected by injury: publications on knee injuries (78.2%) had a higher validity than those on foot injuries (46.2%), and publications on severe injuries had a higher validity (joint dislocation: 100%; ligament rupture: 82.9%; fracture: 73.3%) than those on minor injuries. Publications on specific severe soccer injuries, such as anterior cruciate ligament (ACL) injuries, had a validity of 100%.

Conclusion

Media-based injury data were only valid for a few severe injury types such as ACL injuries. In daily soccer routine and scientific research, media-based data should thus only be used in combination with specific criteria or verification processes.

Decreased external rotation strength is a risk factor for overuse shoulder injury in youth elite handball athletes

PURPOSE

Overuse shoulder injuries are common in youth handball, but research is limited. The purpose of this study was to identify pre-season risk factors associated with overuse shoulder injuries in this population.

METHODS

One-hundred and thirty-eight (70 boys and 68 girls) youth elite players (age 14.1 ± 0.8 years, height 175.2 ± 8.2 cm, weight 64.0 ± 9.6 kg) completed a pre-season screening protocol. Passive glenohumeral range of motion and maximum external (ER) and internal rotation (IR) strength were measured with a manual goniometer and a hand-held dynamometer. Scapular dyskinesia and maximum throwing velocity were also assessed. Players completed standardised questionnaires over the 2017-2018 season and reported any overuse shoulder symptoms.

RESULTS

Decreased isometric and eccentric ER strength was identified as a risk factor for overuse shoulder injury, both for absolute (OR 10.70, 95% CI 1.2-95.6, p = 0.034) and normalised ER strength (OR 1.2, 95% CI 1.0-1.4, p = 0.015) and the ER:IR strength ratio (OR 1.2, 95% CI 1.1-1.5, p = 0.012). ER gain of more than 7.5° (p = 0.025) and GIRD of more than 7.5° (p = 0.014) were identified as risk factors for overuse shoulder injury in girls. Scapular dyskinesia (OR 1.1, n.s.) and maximum throwing velocity did not seem to contribute to injury risk. The average response rate was 63%.

CONCLUSION

In elite youth handball, deficits in ER strength is a risk factor for overuse shoulder injury for both sexes; ER gain and GIRD are only risk factors for girls. Focused pre-season assessments may aid the identification of risk factors for shoulder overuse injuries and the application of specific programmes to reduce risk.

LEVEL OF EVIDENCE

II.

Simplified Measurement of Maximum Strength After Knee Surgery: Application-Based Knee-Training Device Compared to Isokinetic Testing

Context

Isokinetic testing is used as a standard tool in measuring strength in professional athletes. It is often used to evaluate improvement during rehabilitation. The disadvantages of isokinetic testing include its costs, the fact that it is not portable, and its risk of injury, which makes it not suitable for early postoperative rehabilitation.

Hypothesis

The aim of this study was to investigate the relationship between the results of the isokinetic testing and the measurements of an application-based knee-training device.

Study Design

Exploratory diagnostic study.

Methods

In this monocentric study, 100 subjects performed an isokinetic maximum strength examination and an assessment on the application-based knee-training device in a randomized order. The isokinetic testing was based on the Swiss Olympic protocol with 3 sets of 5 repetitions of maximum strength testing for flexion and extension. The subjects consisted of 50 healthy professional athletes and 50 healthy recreational athletes, half male and half female, between the ages of 18 to 30 years old.

Results

No medical or technical issues were reported. The analysis of the relationship between application-based knee-training device and extension showed a Pearson correlation coefficient of r=0.667 for the left knee and r=0.604 for the right knee. For flexion, the Pearson correlation coefficient was r=0.640 for the left side and r=0.673 for the right side. When strength measured by the application-based knee-training device was adjusted for height and weight of the subjects, the Pearson correlation was even stronger (extension left: r=0.727, right: r=0.689; flexion left: r=0.641, right: r=0.711).

Conclusion

The study shows a moderate to high correlation between isokinetic testing and the application-based knee-training device. These results suggest that the application-based knee-training device is effective for early strength rehabilitation without the risk of injury.

Attenuation of Hypertrophy in Human MSCs via Treatment with a Retinoic Acid Receptor Inverse Agonist

In vitro chondrogenically differentiated mesenchymal stem cells (MSCs) have a tendency to undergo hypertrophy, mirroring the fate of transient “chondrocytes” in the growth plate. As hypertrophy would result in ossification, this fact limits their use in cartilage tissue engineering applications. During limb development, retinoic acid receptor (RAR) signaling exerts an important influence on cell fate of mesenchymal progenitors. While retinoids foster hypertrophy, suppression of RAR signaling seems to be required for chondrogenic differentiation. Therefore, we hypothesized that treatment of chondrogenically differentiating hMSCs with the RAR inverse agonist, BMS204,493 (further named BMS), would attenuate hypertrophy. We induced hypertrophy in chondrogenic precultured MSC pellets by the addition of bone morphogenetic protein 4. Direct activation of the RAR pathway by application of the physiological RAR agonist retinoic acid (RA) further enhanced the hypertrophic phenotype. However, BMS treatment reduced hypertrophic conversion in hMSCs, shown by decreased cell size, number of hypertrophic cells, and collagen type X deposition in histological analyses. BMS effects were dependent on the time point of application and strongest after early treatment during chondrogenic precultivation. The possibility of modifing hypertrophic cartilage via attenuation of RAR signaling by BMS could be helpful in producing stable engineered tissue for cartilage regeneration.

Prevention of severe knee injuries in men's elite football by implementing specific training modules

PURPOSE

Injury prevention of knee injuries by means of training and warm-up exercises has been investigated in several studies in amateur football. However, the number of investigations in elite football is limited despite the currently higher injury incidence of severe knee injuries. Therefore, the purpose of this study was to investigate whether specifically adapted preventive training modules may reduce severe knee injuries in elite football.

METHODS

In a prospective controlled cohort study of elite football players in Germany, an injury prevention programme with 5 modules was implemented in the season of 2015-2016. The training modules were specifically adapted to this skill level and based on scientific evidence, team coach preferences, and the specific environment of this playing level. Of the 62 teams taking part in this study, 26 used the new trainings modules and 36 continued their standard programme as a control group. Success of the programme was documented by means of an injury report over one season. The primary outcome was reduction in severe knee injuries.

RESULTS

A pre-seasonal investigation had identified five modules to be implemented in the training routine. Postural stability, mobilisation of lower extremity joints, leg and trunk stabilisation, jumping, and landing exercises as well as agility movements were incorporated into the programme to prevent severe knee injuries in elite football. Over the season, the study group (529 players) with the adapted training modules had sustained 52 severe knee injuries (incidence: 0.38 per 1000 h football exposure; prevalence: 9.8%) compared to 108 severe knee injuries in the control group (601 players) using the standard programme (incidence: 0.68 per 1000 h football exposure; prevalence: 18.0%; p < 0.05). The overall injury incidence for any other type of injury was comparable between the two groups (3.3 vs. 3.4 in h 1000 football, n.s.).

CONCLUSION

Appropriate preventive training modules reduce severe knee injuries in elite football significantly. The key for the sustainability of preventive training measures are programmes specifically adapted to the demands of the playing level and to the preferences of the coaches LEVEL OF EVIDENCE: II.

Improving Maximal Strength in the Initial Postoperative Phase After Anterior Cruciate Ligament Reconstruction Surgery: Randomized Controlled Trial of an App-Based Serious Gaming Approach

Background

Anterior cruciate ligament reconstruction surgery is one of the most common orthopedic procedures. One of the main factors that influence the outcome is regaining strength in the postoperative phase. Because anterior cruciate ligament reconstruction surgeries are often performed in young patients, we combined the concept of prehabilitation with an app-based serious gaming approach to improve maximal strength postoperatively.

Objective

Our objective was to conduct a prospective randomized trial to evaluate whether an app-based active muscle training program (GenuSport Knee Trainer) can improve postoperative strength by starting rehabilitation immediately after primary anterior cruciate ligament reconstruction surgery.

Methods

We designed a pilot study in which we randomly assigned patients receiving primary anterior cruciate ligament reconstruction to either the serious gaming training (intervention) group or a conventional rehabilitation (control) group. Except for the serious gaming-based training, both groups followed the same postoperative treatment protocol. Outcome parameters were absolute and relative change in maximal strength, as well as the International Knee Documentation Committee Subjective Knee evaluation form, Knee Injury and Osteoarthritis Outcome Score, and Lysholm Knee Score.

Results

In total 26 patients agreed to participate (14 patients in the intervention group and 12 patients in the control group, 1 of whom was lost to follow-up). We noted a difference in absolute maximum strength between the exergaming intervention and the control groups. Mean maximum strength preoperatively was 155.1 (SD 79.2) N in the intervention group (n=14) and 157.0 (SD 40.8) N in the control group (n=11). Postoperative mean maximum strength was 212.8 (SD 78.5) N in the intervention group and 154.5 (SD 27.1) N in the control group. Mean absolute change in maximum strength was 57.7 (SD 95.2) N in the intervention group and –4.8 (22.2) N in the control group. The analysis of covariance model with absolute change as the dependent variable and treatment group and baseline maximum strength as covariates showed a relevant difference in relative change between treatment groups (intervention – control) of 59.7 N (95% CI 10.1-109.3; P=.02). Similarly to the absolute increase, the relative change in maximum strength was relevantly higher in the exergaming group. The mean relative change in maximum strength was 1.7 (SD 1.17) in the intervention group and 1 (SD 0.13) in the control group. No adverse events or problems were reported during the study period.

Conclusions

Implementation of an app-based active muscle training program in the early postoperative therapy scheme was associated with an improvement in maximal strength. Therefore, we considered the use of GenuSport training after anterior cruciate ligament reconstruction to be a helpful complement to rehabilitation after anterior cruciate ligament reconstruction surgery to improve strength in the early postoperative phase. To our knowledge this was the first study to analyze immediate postoperative serious gaming-based training with the GenuSport device based on strength improvement.

Contact - but not foul play - dominates injury mechanisms in men's professional handball: a video match analysis of 580 injuries

AIM

We aimed to identify patterns and mechanisms of injury situations in men's professional handball by means of video match analysis.

METHODS

Moderate and severe injuries (absence of >7 days) sustained in competition in one of six seasons (2010 to 2013 and 2014 to 2017) in men's professional handball were prospectively analysed with a newly developed standardised observation form. Season 2013 to 2014 was excluded because of missing video material.

RESULTS

580 injuries were identified: 298 (51.4%) contact injuries, 151 (26.0%) indirect contact injuries and 131 (22.6%) non-contact injuries. Head (87.5%), hand (83.8%), shoulder (70.2%) and ankle (62.9%) injuries were mainly sustained during direct contact. Typical contact injuries included collision with an opponent's upper extremity or torso, and ankle injuries mainly consisted of foot-to-foot collisions. A large proportion (41.7%) of knee injuries were caused by indirect contact, whereas thigh injuries mainly occurred (56.4%) through non-contact mechanism. Wing (56.9%) and pivot (58.4%) players had the highest proportion of contact injuries, whereas backcourt players had a high proportion of indirect contact injuries (31.5%) and goalkeepers of non-contact injuries (48.9%). The injury proportion of foul play was 28.4%. Most injuries occurred in the central zone between the 6-metre and 9-metre lines (26.1%) and during the last 10 min of each match half (OR 1.71, p=0.016).

CONCLUSIONS

In men's professional handball in a league setting, contact - but not foul play - was the most common mechanism associated with moderate and severe injuries. Head, hand, shoulder and ankle injury were mainly sustained during direct contact.

Injury Incidence Rates and Profiles in Elite Taekwondo during Competition and Training

This study aimed to investigate exposure adjusted injury incidence rates and profiles associated with training and competition in an elite taekwondo athlete population. 82 athletes were investigated for injuries over a period of 5 years. Individual fight time exposure for training and competition was recorded. The type and location of the injuries were classified and exposure-adjusted injury incidence rates (IIR) were calculated per 1000 h for training and competition. 66 athletes with a mean age of 19.3±4.2 years and 172 injuries were included in the final data assessment. The exposure adjusted IIR was significantly higher during competition (p<0.001) with a rate ratio of 6.33 (95% CI 4.58-8.69). Ankle and foot region as well as hand and wrist were most affected with significant higher IIR in competition (p<0.001). Joint injuries, fractures, and bruising occurred the most. Fractures occurred mainly to the hand and wrist region. Future investigations should focus on exposure adjusted injury data including analyses of the detailed mechanism leading to especially severe injuries to improve specific injury prevention in competition and promote evolution of protective gear.

["Stay and play" in football : Art of keeping players fit to play]

Many publications about the treatment and return to play after severe football injuries are available from the scientific literature, particularly about injuries requiring surgery. In contrast, less severe football injuries, such as muscle strains, ankle sprains and contusions, are less well addressed in the literature although these represent the most frequent type of injury. Additionally, such reports often have a low level of evidence and guidelines on treatment and the return to play process are very rare. Thus, the time away from football and the timing of return to play after minor injuries depends on the experience and skills of the responsible medical team. To achieve the aim of stay and play on the field, the medical team should be highly knowledgeable in interdisciplinary football medicine, prevention strategies, first aid on the field, clinical and manual diagnostics, tissue regeneration, symptomatic and conservative treatment as well as in return to play decision-making. No consensus exists on stay and play procedures neither on the practical level nor on the scientific level regarding injury definition, the diagnostic and treatment options and stay and play criteria. Therefore, this article presents the first steps for assessing stay and play strategies after minor injuries to standardize and improve practical routine, education and scientific research.

Functional Deficits in the Wrist and Finger Joints of Goalkeepers After 20 Years of Playing Recreational Football

BACKGROUND

 Long-term damage in the hip, knee and ankle joints of football players has been thoroughly discussed in the literature. Compared with outfield players, however, goalkeepers sustain injuries to the upper extremities five times more often. There is a lack of studies on long-term functional damage to the wrist and finger joints of football goalkeepers.

HYPOTHESIS

 Repetitive micro-traumas and injuries lead to degenerative diseases in goalkeepers after 20 years of playing recreational soccer.

METHODS

 The personal histories, injury histories and clinical examination findings of the wrist and finger joints of 27 goalkeepers were compared with the findings obtained in a control group of outfield players.

RESULTS

 Goalkeepers were significantly more restricted in finger movement (p < 0.05) and experienced more pain and swelling (p < 0.05) as well as higher levels of instability (p < 0.05) in the wrist and finger joints than outfield players.

CONCLUSION

 Medical history and clinical findings indicate deficits in the hands of soccer goalkeepers and a high prevalence of joint and ligament injuries sustained to the fingers over the course of their sports activity. This necessitates specific strategies in the future to prevent injuries and long-term posttraumatic deficits.

Time before return to play for the most common injuries in professional football: a 16-year follow-up of the UEFA Elite Club Injury Study

Objectives

The objective was to describe the typical duration of absence following the most common injury diagnoses in professional football.

Methods

Injuries were registered by medical staff members of football clubs participating in the Union of European Football Association Elite Club Injury Study. Duration of absence due to an injury was defined by the number of days that passed between the date of the injury occurrence and the date when the medical team allowed the player to return to full participation. In total, 22 942 injuries registered during 494 team-seasons were included in the study.

Results

The 31 most common injury diagnoses constituted a total of 78 % of all reported injuries. Most of these injuries were either mild (leading to a median absence of 7 days or less, 6440 cases = 42%) or moderate (median absence: 7–28 days, 56% = 8518 cases) while only few (2% = 311 cases) were severe (median absence of >28 days). The mean duration of absence from training and competition was significantly different (p < 0.05) between index injuries and re-injuries for six diagnoses (Achilles tendon pain, calf muscle injury, groin adductor pain, hamstring muscle injuries and quadriceps muscle injury) with longer absence following re-injuries for all six diagnoses

Conclusions

The majority of all time loss due to injuries in professional football stems from injuries with an individual absence of up to 4 weeks. This article can provide guidelines for expected time away from training and competition for the most common injury types as well as for its realistic range.

Relation of injuries and psychological symptoms in amateur soccer players

Objectives

The first main goal of this study was to investigate the prevalence of depression and anxiety as well as self-compassion in a heterogeneous sample of male amateur soccer players. The second main goal of this study was the examination of the relationship between injuries and psychological factors in amateur soccer players.

Methods

Players were recruited from German amateur soccer clubs of the fourth to seventh league. 419 soccer players with the mean age of 22.88 years participated in the psychological and the injury assessment at the beginning of the season and at the end, 9 months later. For the psychological assessment, depression and anxiety rate as well as self-compassion was analysed. Furthermore, the frequencies of injuries were registered.

Results

The results showed that players of the highest amateur league, the fourth league in German soccer, showed significantly higher anxiety values than players from a lower league (p=0.013). There were no differences in depression values dependent on the league. Furthermore, players who suffered from an injury before the start of the season demonstrated higher anxiety values (p=0.027). This result was independent of the respective league.

Conclusion

The results of this study demonstrate that even in higher amateur soccer the anxiety level of the players varies between soccer players of different leagues. Because an injury before the start of the season influenced the anxiety level, a psychological treatment during injury should be considered.

Injury incidence in semi-professional football claims for increased need of injury prevention in elite junior football

PURPOSE

Injuries are a common occurrence in football. Sufficient epidemiological data are available in professional football but not in salaried semi-professional football. This study investigates the injury incidence at different levels of semi-professional football with focus on junior football.

METHODS

The data were based on injury reports provided by players and medical staff over the 2015-2016 season, which corresponded to the consensus statement for data samples in football. This study investigated the injury incidence and prevalence of five skill levels of semi-professional football (the fourth to the seventh league and elite junior football).

RESULTS

1130 players had sustained 2630 injuries over the 2015-2016 season. The overall injury incidence was 9.7 per 1000 h football exposure; prevalence with at least one injury was 79%. The highest overall injury incidence in elite junior football was 10.4 in 1000 h football exposure. The fifth league had the lowest incidence with 9.0 in 1000 h football (p < 0.05). Traumatic injuries most often occurred in the fourth league (3.9 in 1000 h football). The body areas most affected by traumatic injury were knees, ankles and thighs. Elite junior players had a significantly higher incidence of overuse complaints (7.4 in 1000 h football) than the fourth league (5.4, p = 0.005). The body areas most affected by overuse complaints were the lower back, thigh and groin. No differences were found between the different positions on field.

CONCLUSIONS

Salaried semi-professional football involves a high overall injury incidence. The highest incidence, particularly of overuse injuries, was seen in elite junior football. These findings should be incorporated in specific injury prevention training or screenings beginning in junior football. Level of evidence II.

Early functional rehabilitation after patellar dislocation-What procedures are daily routine in orthopedic surgery?

INTRODUCTION

Patellar dislocation and rupture of the medial patellofemoral ligament (MPFL) are frequently seen in daily orthopedic practice. Besides initial non-surgical treatment, surgery and subsequent rehabilitation are crucial for restoring stability in the femoropatellar joint. This study investigated current rehabilitation strategies after patellar dislocation because knowledge on this topic has been severely limited so far.

MATERIALS AND METHODS

The current rehabilitation protocols of 42 orthopedic and trauma surgical institutions were analyzed regarding their recommendations on weight bearing, range of motion (ROM), and use of movement devices and orthosis. All protocols for conservative treatment and postoperative rehabilitation after MPFL reconstruction were compared. Descriptive and statistical analyses were carried out when appropriate.

RESULTS

The different rehabilitation strategies for conservative and surgical treatment after patellar dislocation showed a tendency towards earlier functional rehabilitation after surgical MPFL reconstruction than after conservative treatment. Both surgical and conservative treatment involved initial restrictions in weight bearing, ROM, and use of movement devices and orthosis at the beginning of rehabilitation. The rehab protocols showed a significant earlier full weight bearing after surgical MPFL reconstruction (p > 0.001). Due to the presence of other parameters for early functional treatment, the absence of an indication for using orthosis (surgical: 44%, conservative: 33%; p = 0.515) or start of unlimited ROM of the knee (surgical: 4.9 weeks, conservative: 5.7 weeks; p = 0.076) showed by trend an earlier functional strategy after MPFL reconstruction than after conservative therapy.

CONCLUSIONS

Both conservative and surgical treatment after patellar dislocation showed restrictions in the early phase of the rehabilitation. Earlier functional therapy was more common after MPFL reconstruction than after conservative treatment. Further clinical and biomechanical studies on rehabilitation strategies after patellar dislocation are needed to improve patient care und individualized therapy.

Contact times of change-of-direction manoeuvres are influenced by age and the type of sports: a novel protocol using the SpeedCourt® system

PURPOSE

Side-to-side asymmetry in side-cutting manoeuvres is a known risk factor for severe knee injury. Potential leg asymmetry during ground contact times of different change-of-direction manoeuvres was evaluated in athletes by means of the recently developed SpeedCourt^® system. The hypotheses were that ground contact times and the limb symmetry index are affected by age and the type of sports.

METHODS

One-hundred and sixty-five athletes (149 men, 16 women, age 16.5 ± 5.1) of popular team sports such as football, team handball and baseball were assessed by means of three different tests [side-hop, lateral change-of-direction (COD) and diagonal COD] using the SpeedCourt^® system. Analysis included the factors age, sex, type of sports, ground contact time, leg symmetry index and limb dominance.

RESULTS

During lateral but not diagonal COD tests, football players had shorter contact times than players of team handball (p = 0.026) and baseball (p = 0.015) of the same age group. The side-hop tests yielded differences in the leg symmetry index between players < 16 years and players > 16 years (p < 0.01). Mean ground contact time differed in each of the side-hop, lateral COD and diagonal COD tests (143.5 ± 20.0 vs. 256.2 ± 66.1 vs. 320.4 ± 55.0). Contact times and test durations of side-hop, lateral COD and diagonal COD tests were shorter for older players (p < 0.01).

CONCLUSIONS

Ground contact times of side-hop and change-of-direction manoeuvres are influenced by age, the type of sports and limb dominance. Such information is fundamental for future sports medicine research and needs to be considered in pre-season screening or when used as a criterion for return-to-competition of players with previous severe knee injury. Assessment of change-of-direction manoeuvres should be included in future return-to-competition test batteries.

LEVEL OF EVIDENCE

III.

Echocardiographic diagnosis of congenital coronary artery abnormalities in a continuous series of adolescent football players

Background

Sudden cardiac death (SCD) in children and adolescents is rare. Several studies have reported a higher risk of SCD during athletic competition. High risk congenital coronary artery abnormalities are the second leading cause of SCD in young athletes in the USA. Echocardiographic assessment of coronary arteries has not been routinely used in screening programmes for junior athletes so far.

Design

Prospective cohort study in 1045 consecutive adolescent elite football players.

Methods

All athletes underwent a standardized cardiovascular screening protocol with a medical history, a physical examination, 12-lead resting electrocardiogram and a complete transthoracic 2D-echocardiography.

Results

Two athletes (0.19%) showed a high-risk coronary artery abnormality (CAA) with a right coronary artery originating abnormal from the aorta and coursing inter-arterial. Low-risk CAAs were found in 16 athletes (1.53%). There was an ectasia of the left coronary artery (+3.9z and +4.3z) and a fistula from the left coronary artery in two cases (0.19%), respectively. In 1.05% ( n = 11) we found a high take-off (2.3–6.8 mm) and in one case (0.096%) there was a tangential take-off of the right main coronary artery. Variants of coronary arterial anatomy were identified in 335 of 1045 athletes (32.06%).

Conclusion

Basic pre-participation screening tests including 12-lead or exercise electrocardiogram do not safely identify high-risk CAAs. In adolescent athletes an expert cardiologist is able to describe the origin and the proximal course of the coronary arteries and identify major abnormalities in most of the cases by transthoracic 2D-echocardiography.

Injury prevention and return to play strategies in elite football: no consent between players and team coaches

INTRODUCTION

Injuries are a common problem in football. To improve prevention strategies, the players' (p) and coaches' (c) views need to be disclosed as they have a strong impact on return to play decisions. The aim of this study is to reveal current opinions with regard to injury prevention and return to play strategies to introduce new strategies in elite football.

MATERIALS AND METHODS

In a retrospective data analysis of elite salaried football players (n = 486) and team coaches (n = 88), a detailed investigation by means of a standardized questionnaire was carried out. In a preseason period of the 2015/16 season and as part of a large interventional research project in elite salaried German football, a request about players' and team coaches' knowledge and opinions was performed. Topics such as injury prevention, return to play after injuries, the importance of screening tests, general problems of injuries in football, or the decision-making in terms of prevention and return to play in elite football were investigated.

RESULTS

The study revealed a high interest in injury prevention and screening tests among players and coaches (p 82.5%; c 99.1%). The participants of the study reported warm-up exercises (p 76.4%; c 74.7%), regeneration training (p 54.1%; c 56.3%), and core stability (p 53.8; c 70.1%) as the most important prevention methods, but the additional investigation of the teams' current daily training routine showed that the transfer is incomplete. Coaches are more familiar with scientific published warm-up programs like FIFA 11 + than players (42.5 vs. 12.6; p < 0.001). Knee injuries (p 90.7%; c 93.1%) and ACL injuries in particular were reported as the most severe and common problem in elite football. Players and coaches expressed different attitudes concerning return to play decisions. While players want to decide themselves (81.4%), team coaches consult medical advice ahead of the decision of return to play after injuries (83.5%; p < 0.001). Decisions against the doctor's recommendation are often made by both groups (p 64.4% vs. c 87.1%; p < 0.001).

CONCLUSION

The basic knowledge of prevention and injuries is sufficient in elite football, but the transfer from theoretical knowledge to practical routine is suboptimal. The study also shows possibilities to improve the prevention process and communication between players, coaches, doctors, and physiotherapists, while there is no consent between players and coaches regarding return to play decision.

11.361 sports injuries in a 15-year survey of a Level I emergency trauma department reveal different severe injury types in the 6 most common team sports

INTRODUCTION

Severe sports-related injuries are a common affliction treated in Level I trauma departments. Detailed knowledge on injury characteristics from different medical settings is essential to improve the development of injury prevention strategies in different team sports.

METHODS

Team sport injuries were retrospectively analysed in a Level I trauma department registry over 15 years. Injury and treatment data were compared with regard to competition and training exposure. Injury data such as "time of visitation", "type of injury", "multiple injured body regions" and "immediate hospitalisation" helped to define the severity level of each team sports injury.

RESULTS

At the Level I trauma department, 11.361 sports-related injuries were seen over 15 years, of which 34.0 % were sustained during team sports. Soccer injuries were the most common injuries of all team sports (71.4 %). The lower extremity was the most affected body region overall, followed by the upper extremity. Head injuries were mainly seen in Ice hockey and American football and concussion additionally frequently in team handball. Slight injuries like sprains or contusions occurred most frequently in all team sports. In soccer and team handball, injuries sustained in competition were significantly more severe (p < 0.001) than those sustained in practice.Volleyball and basketball had a trend to higher rate of severe injuries sustained during practice sessions.

CONCLUSION

Depending on the specific injury profile of each team sports, injury prevention strategies should address competitive as well as training situations, whichmay need different strategies.

Intra-ligamentary autologous conditioned plasma and healing response to treat partial ACL ruptures

INTRODUCTION

Conservative treatment of partial ACL ruptures is associated with a high failure rate, and often patients undergo ACL reconstruction. ACL preservation by trephination of the ACL origin and application of Autologous Conditioned Plasma (ACP) seems to be an intriguing new treatment option to favour ACL tissue healing and avoid traditional reconstruction. The aim of this study was to describe the mid-term outcomes of this new ACL preserving technique.

MATERIALS AND METHODS

Twenty-four patients (mean age 41.8 years) affected by partial rupture of one or both ACL bundles were included in the present trial. The partial ACL tears were arthroscopically assessed and classified according to a new five step grading system. All patients were treated by trephination of the femoral ACL stump and intra-ligamentary application of ACP. The postoperative outcome was evaluated by both subjective scores and stability testing up to a mean of 25.1 months' follow-up. Adverse events and failure rate were also documented.

RESULTS

Clinical outcome was good to excellent with IKDC subjective 82.7 (SD 11.8), Lysholm 87.6 (SD 8.1), Tegner 5.3 (SD 2.1), Cincinnati 88.7 (SD 14.8). The failure rate (i.e. persisting knee instability assessed clinically or by rolimeter) was 12.5%. At objective measurements, knee joints showed a firm endpoint in Lachman test, negative pivot shift phenomenon and a significant reduction in AP-laxity compared to pre-operative status by rolimeter testing (p = 0.002). Return to sport practice was achieved after mean 4.8 months (SD 4.1).

CONCLUSIONS

ACL stump trephination and concomitant intra-ligamentary application of ACP revealed promising results at mid-term follow-up to treat partial ACL lesions.

Correction to: Intra-ligamentary autologous conditioned plasma and healing response to treat partial ACL ruptures

With regards to Berardo Di Matteo, second author. The author's name is incorrectly listed on Pub-Med. The first and last name have been mixed up.

Reduced joint-awareness in bicruciate-retaining total knee arthroplasty compared to cruciate-sacrificing total knee arthroplasty

PURPOSE

There is rising impact of patient-reported outcome (PRO) measurement in joint arthroplasty over the past years. Bicruciate-retaining implants have shown more physiologic knee kinematics and provide superior proprioceptive capacities. The aim of this study was to evaluate if the functional properties of this new implant design lead to improved PRO results after total knee arthroplasty (TKA).

METHODS

This prospective, controlled trial compares PRO of bicruciate-retaining total knee arthroplasty (BCR-TKA) to unicondylar knee arthroplasty (UKA) and standard posterior-stabilized total knee arthroplasty (PS-TKA). We evaluated 102 patients (34 patients in each group) 18 months postoperatively after knee arthroplasty. Primary outcome measure was the Forgotten Joint Score (FJS).

RESULTS

The BCR-group showed the same level of joint awareness as the UKA-group (p = 0.999). The second control group of PS-TKA patients had a lower mean score value in the FJS compared to the BCR-group (p = 0.035) and UKA-group (p = 0.031). There was no correlation of age, gender, body mass index (BMI) and the FJS. No relevant floor- or ceiling effects occurred.

CONCLUSIONS

This study found reduced joint awareness for BCR-TKA compared to a standard total knee arthroplasty. The score values of the BCR-group were equal to the UKA-group. Further prospective, randomized studies to investigate long-term survivorship of bicruciate-retaining implants are needed.

LEVEL OF EVIDENCE

Level II.

Sports-specific differences in postsurgical infections after arthroscopically assisted anterior cruciate ligament reconstruction

PURPOSE

Post-operative infection after arthroscopically assisted anterior cruciate ligament (ACL) reconstruction is a rare but severe complication, particularly for young and active patients. It is unclear whether the prevalence of knee infection is correlated with the type of sports or the level of performance.

METHODS

From 2008 to 2012, the internal single-centre ACL registry of the FIFA Medical Centre of Excellence Regensburg was retrospectively screened for sex, age, time between isolated primary ACL rupture and surgery, surgical technique, rate of infection after ACL reconstruction and the type of sports practised.

RESULTS

In total, 4801 ACL reconstructions had been conducted over 5 years, 4579 in amateur and 221 in professional athletes. After application of the exclusion criteria, 1809 athletes with ACL reconstruction were analysed regarding postsurgical infection and the type of sports practised. Professionals and amateurs did not significantly differ with regard to infection rates (n.s.) but in the timing of ACL repair (p < 0.001). Eleven of 1130 football players had developed postsurgical infection after ACL reconstruction (1.0%) in contrast to 557 skiers and snowboarders without infection (p = 0.02). The timing of ACL repair did not differ between the different types of sports (n.s.). Staphylococcus aureus and epidermidis were the predominant detected bacteria. All patients were hospitalised and successfully treated with arthroscopic lavage and antibiotic medication.

CONCLUSION

ACL infections showed sports-related differences. Athletes practising summer outdoor sports such as football had a significantly higher risk of infection after ACL reconstruction than winter sports athletes. No difference was found between professional and amateur athletes. Relevant prevention strategies for postsurgical ACL infections should consider influencing patient factors such as the type of sports activity and attendant circumstances.

LEVEL OF EVIDENCE

III.

Clinical and Radiological Regeneration of Large and Deep Osteochondral Defects of the Knee by Bone Augmentation Combined With Matrix-Guided Autologous Chondrocyte Transplantation

BACKGROUND

Large osteochondral defects of the knee are a challenge for regenerative treatment. While matrix-guided autologous chondrocyte transplantation (MACT) represents a successful treatment for chondral defects, the treatment potential in combination with bone grafting by cancellous bone or bone block augmentation for large and deep osteochondral defects has not been evaluated.

PURPOSE

To evaluate 1- to 3-year clinical outcomes and radiological results on magnetic resonance imaging (MRI) after the treatment of large osteochondral defects of the knee with bone augmentation and MACT. Special emphasis is placed on different methods of bone grafting (cancellous bone grafting or bone block augmentation).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifty-one patients were included. Five patients were lost to follow-up. This left 46 patients (mean age, 28.2 years) with a median follow-up time of 2 years. The 46 patients had 47 deep, large osteochondral defects of the knee joint (1 patient with bilateral defects; mean defect size, 6.7 cm²). The origin of the osteochondral defects was osteochondritis dissecans (n = 34), osteonecrosis (n = 8), or subchondral cysts (n = 5). Depending on the depth, all defects were treated by cancellous bone grafting (defect depth ≤10 mm; n = 16) or bone block augmentation (defect depth >10 mm; n = 31) combined with MACT. Clinical outcomes were followed at 3 months, 6 months, 1 year, 2 years, and 3 years and evaluated using the International Knee Documentation Committee (IKDC) score and Cincinnati score. A magnetic resonance imaging (MRI) evaluation was performed at 1 and 2 years, and the magnetic resonance observation of cartilage repair tissue (MOCART) score with additional specific subchondral bone parameters (bone regeneration, bone signal quality, osteophytes, sclerotic areas, and edema) was analyzed.

RESULTS

The clinical outcome scores revealed a significant increase at follow-up (6 months to 3 years) compared with the preclinical results. The median IKDC score increased from 42.6 preoperatively to 75.3 at 1 year, 79.7 at 2 years, and 84.3 at 3 years. The median Cincinnati score significantly increased from 39.8 preoperatively to 72.0 at 1 year, 78.0 at 2 years, and 80.3 at 3 years. The MRI evaluation revealed a MOCART score of 82.6 at 1 year without a deterioration at the later follow-up time point. Especially, the subchondral bone analysis showed successful regeneration. All bone blocks and cancellous bone grafts were integrated in the bony defects, and no chondrocyte transplant failure could be detected throughout the follow-up.

CONCLUSION

Large and deep osteochondral defects of the knee joint can be treated successfully with bone augmentation and MACT. The treatment of shallow bony defects with cancellous bone grafting and deep bony defects with bone block augmentation shows promising results.