Most modifiable risk factors for hamstring muscle injury in women's elite football are extrinsic and associated with the club, the team, and the coaching staff and not the players themselves: the UEFA Women's Elite Club Injury Study.

PURPOSE: To describe the perceived importance of suggested hamstring injury risk factors according to chief medical officers (CMOs) of European women's professional football clubs. A secondary objective was to compare if these perceptions differed between teams with a lower-than-average and higher-than-average hamstring injury burden. METHODS: The CMOs of eleven European professional women's football clubs were initially asked to suggest modifiable risk factors for hamstring injury. These risk factors were rated in according with their perceived importance on a 5-graded Likert scale. Participating teams were divided in two groups depending on their hamstring injury burden during the 2020/21 season. The LOW group consisted of six teams that had a lower-than-average hamstring injury burden. The HIGH group consisted of five teams that had a higher-than-average hamstring injury burden. RESULTS: Twenty-one risk factors were suggested, most of which were extrinsic in nature, hence associated with the coaching staff, the team or the club organization rather than with the players themselves. The risk factors with the highest average importance were: "lack of communication between medical staff and coaching staff" and "load on players" (each with a weighted average of 3.9), followed by "lack of regular exposure to high-speed football actions during training" and "playing matches 2-3 times a week" (weighted average of 3.8 and 3.7). Differently from the LOW group, the HIGH group perceived the coaching factors (style of coach leadership, training/exercise surveillance by coaching staff) as more important. CONCLUSION: In accordance to the eleven CMOs recruited in this study, most risk factors for hamstring injuries are extrinsic in nature and associated with the club, the team, and the coaching staff, and not the players themselves. LEVEL OF EVIDENCE: Level III.

Anterior ankle impingment syndrome is less frequent, but associated with a longer absence and higher re-injury rate compared to posterior syndrome: a prospective cohort study of 6754 male professional soccer players.

PURPOSE: To study the epidemiology and return to play characteristics of anterior and posterior ankle impingement syndromes (AAIS and PAIS) over 18 consecutive seasons in male professional soccer players. METHODS: Between the 2001-2002 and 2018-2019 seasons, 120 European soccer teams were followed prospectively for various seasons. Time loss injuries and player exposures were recorded individually in 6754 unique players. Injury incidence and burden were reported as the number of injuries and days absence per 1000 h with 95% confidence intervals (CIs). Injury severity was reported as median absence in days with the interquartile range (IQR). RESULTS: Out of 25,462 reported injuries, 93 (0.4%) were diagnosed as AAIS (38%) or PAIS (62%) in 77 players. AAIS and PAIS were similar regarding injury characteristics except for a greater proportion of AAIS having a gradual onset (69% vs.47%; P = 0.03) and being re-injuries (31% vs. 9%; P = 0.01). Impingement syndromes resulted in an overall incidence of 0.03 injuries (95% CI 0.02-0.03) per 1000 h and an injury burden of 0.4 absence days per 1000 h. PAIS incidence was significantly higher than that for AAIS [0.02 (95% CI 0.002-0.03) vs. 0.01 (95% CI 0.005-0.01) injuries per 1000 h (RR = 1.7). The absence was significantly longer in AAIS than in PAIS [10 (22) vs. 6 (11) days; P = 0.023]. Impingement syndromes that presented with a gradual onset had longer absences in comparison to impingement with an acute onset [8 (22) vs. 5 (11) days; P = 0.014]. Match play was associated with a higher incidence and greater injury burden than training: 0.08 vs. 0.02 injuries per 1000 h (RR 4.7), respectively, and 0.9 vs. 0.3 days absence per 1000 h (RR 2.5). CONCLUSION: Ankle injuries are frequent in men's professional soccer and ankle impingement is increasingly recognized as a common source of pain, limited range of motion, and potential time loss. In our study, ankle impingement was the cause of time loss in less than 0.5% of all injuries. PAIS was more frequently reported than AAIS, but AAIS was associated with more absence days and a higher re-injury rate than PAIS. The findings in this study can assist the physician in best practice management on ankle impingment syndromes in professional football. LEVEL OF EVIDENCE: II.

Return to play after surgery for isolated unstable syndesmotic ankle injuries (West Point grade IIB and III) in 110 male professional football players: a retrospective cohort study.

OBJECTIVES: To evaluate time to return to play following surgical stabilisation of isolated unstable syndesmosis injuries in a cohort of professional male football players. METHODS: All professional football players undergoing surgery for isolated unstable syndesmosis injury (West Point grade ≥IIB) at a specialised Orthopaedic and Sports Medicine Hospital were followed up until return to play (minimum ≥6 months). Players with a stable syndesmosis, injuries older than 6 weeks, concomitant medial or lateral malleolar fracture or previous ankle surgery were excluded. During rehabilitation, time required to return to sports-specific rehabilitation, team training and first match play, were recorded. RESULTS: Between January 2012 and December 2017, a total of 110 male professional football players were included. The mean time required to begin on field rehabilitation was 37±12 days, while the mean time to return to team training was 72±28 days. The first official match was played on average 103±28 days postoperatively. Multivariable analysis revealed that the severity of injury, the concomitant presence of talar cartilage injury and the age of the player were significantly associated (p<0.00001) with time to return to on field rehabilitation, team training and match play. CONCLUSION: In this cohort of professional football players, surgical stabilisation of isolated unstable syndesmosis injuries (West Point grade ≥IIB) allowed for relatively quick return to play. High grade injury (West Point grade III), concomitant cartilage injury and greater age were associated with longer return to play times. LEVEL OF EVIDENCE: Longitudinal observational cohort study (level II).

Medial collateral ligament injuries of the knee in male professional football players: a prospective three-season study of 130 cases from the UEFA Elite Club Injury Study.

PURPOSE: Medial collateral ligament (MCL) injury is the single most common traumatic knee injury in football. The purpose of this study was to study the epidemiology and mechanisms of MCL injury in men's professional football and to evaluate the diagnostic and treatment methods used. METHODS: Fifty-one teams were followed prospectively between one and three full seasons (2013/2014-2015/2016). Individual player exposure and time-loss injuries were recorded by the teams' medical staffs. Moreover, details on clinical grading, imaging findings and specific treatments were recorded for all injuries with MCL injury of the knee as the main diagnosis. Agreement between magnetic resonance imaging (MRI) and clinical grading (grades I-III) was described by weighted kappa. RESULTS: One hundred and thirty of 4364 registered injuries (3%) were MCL injuries. Most MCL injuries (98 injuries, 75%) occurred with a contact mechanism, where the two most common playing situations were being tackled (38 injuries, 29%) and tackling (15 injuries, 12%). MRI was used in 88 (68%) of the injuries, while 33 (25%) were diagnosed by clinical examination alone. In the 88 cases in which both MRI and clinical examination were used to evaluate the grading of MCL injury, 80 (92% agreement) were equally evaluated with a weighted kappa of 0.87 (95% CI 0.77-0.96). Using a stabilising knee brace in players who sustained a grade II MCL injury was associated with a longer lay-off period compared with players who did not use a brace (41.5 (SD 13.2) vs. 31.5 (SD 20.3) days, p = 0.010). CONCLUSION: Three-quarter of the MCL injuries occurred with a contact mechanism. The clinical grading of MCL injuries showed almost perfect agreement with MRI grading, in cases where the MCL injury is the primary diagnosis. Not all grade II MCL injuries were treated with a brace and may thus indicate that routine bracing should not be necessary in milder cases. LEVEL OF EVIDENCE: Prospective cohort study, II.

Are severe musculoskeletal injuries associated with symptoms of common mental disorders among male European professional footballers?

PURPOSE: To explore the associations of severe musculoskeletal injuries (joint and muscles) and surgeries with symptoms of common mental disorders (distress, anxiety/depression, sleeping disturbance, adverse alcohol behaviour , smoking, adverse nutrition behaviour) among male European professional footballers. METHODS: Cross-sectional analyses were conducted on electronic questionnaires completed by professional footballers recruited from the national players' unions of Finland, France, Norway, Spain or Sweden. The number of severe (time loss of more than 28 days) musculoskeletal injuries (total, joint, muscle) and surgeries during a professional football career was examined through four questions, while symptoms of common mental disorders were evaluated through validated scales. RESULTS: A total of 540 professional footballers (mean age of 27 years; 54 % playing in the highest leagues) participated in the study. Sixty-eight per cent of the participants had already incurred one or more severe joint injuries and 60 % one or more severe muscle injuries. Prevalence of symptoms of common mental disorders ranged from 3 % for smoking to 37 % for anxiety/depression and 58 % for adverse nutrition behaviour. The number of severe musculoskeletal injuries during a football career was positively correlated with distress, anxiety and sleeping disturbance, while the number of surgeries was correlated with adverse alcohol behaviour and smoking. Professional footballers who had sustained one or more severe musculoskeletal injuries during their career were two to nearly four times more likely to report symptoms of common mental disorders than professional footballers who had not suffered from severe musculoskeletal injuries. CONCLUSION: It can be concluded that the number of severe musculoskeletal injuries and surgeries during a career is positively correlated and associated with symptoms of common mental disorders among male European professional footballers. This study emphasises the importance of applying a multidisciplinary approach to the clinical care and support of professional footballers, especially when a player faces lengthy periods without training and competition as a consequence of recurrent severe joint or muscle injuries. LEVEL OF EVIDENCE: III.

Fifth metatarsal fractures among male professional footballers: a potential career-ending disease.

BACKGROUND: There is little information about Metatarsal Five (MT-5) fractures for specific sports. OBJECTIVE: To study the occurrence, the imaging characteristics, the lay-off times and healing problems of MT-5 fractures among male footballers. METHODS: Sixty-four European elite teams were monitored from 2001 to 2012. x-Rays were collected and classified by the Torg criteria. RESULTS: Of 13 754 injuries, 0.5% (67) proved to be MT-5 fractures. Their incidence was 0.04 injuries/1000 h of exposure. A team of 25 players might thus expect an MT-5 fracture every fifth season. Of these fractures, 67% (38) were primary and 33% were refractures. One of the 38 primary fractures was an avulsion of the tuberosity; all the others (97%) located towards the base. In total, 32% of the players with MT-5 fracture were younger than 21 years, 40% of the fractures occurred during the preseason and 45% of the players had prodromal symptoms. In total, 54% of the initial x-rays were classified as Torg type II (stress fractures), and 46% were classified as Torg type I (acute type). After surgical treatment the fractures healed faster, compared with conservative treatment (75% vs 33%, p<0.05). There was no significant difference in lay-off days between players that had been operated, and those that had not (80 vs 74 days, p=0.67). CONCLUSIONS: The majority of MT-5 fractures are stress fractures, and mainly occur among young players. There are frequent healing problems, which might be explained by the stress nature of the injury. After surgery there are less healing problems, compared with those in conservative treatment.

Upper extremity injuries in male elite football players.

PURPOSE: To investigate the epidemiology of upper extremity injuries in male elite football players and to describe their characteristics, incidence and lay-off times. METHODS: Between 2001 and 2011, 57 male European elite football teams (2,914 players and 6,215 player seasons) were followed prospectively. Time-loss injuries and exposure to training and matches were recorded on individual basis. RESULTS: In total, 11,750 injuries were recorded, 355 (3 %) of those affected the upper extremities giving an incidence of 0.23 injuries/1,000 h of football. The incidence in match play was almost 7 times higher than in training (0.83 vs. 0.12 injuries/1,000 h, rate ratio 6.7, 95 % confidence interval 5.5-8.3). As much as 32 % of traumatic match injuries occurred as a result of foul play situations. Goalkeepers had a significantly higher incidence of upper extremity injuries compared to outfield players (0.80 vs. 0.16 injuries/1,000 h, rate ratio 5.0, 95 % confidence interval 4.0-6.2). The average absence due to an upper extremity injury was 23 ± 34 days. CONCLUSIONS: Upper extremity injuries are uncommon among male elite football players. Goalkeepers, however, are prone to upper extremity injury, with a five times higher incidence compared to outfield players. LEVEL OF EVIDENCE: II.

Diagnosis and prognosis of acute hamstring injuries in athletes.

PURPOSE: Identification of the most relevant diagnostic and prognostic factors of physical examination and imaging of hamstring injuries in (elite) athletes. METHODS: A literature search was conducted in MEDLINE and EMBASE for articles between 1950 and April 2011. A survey was distributed among the members of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy, which focused on physical examination, prognosis, imaging and laboratory tests of hamstring injuries in (elite) athletes. RESULTS: Medical history, inspection and palpation of the muscle bellies and imaging are most valuable at the initial assessment according to the literature. Experts considered medical history, posture and gait inspection, inspection and palpation of muscle bellies, range of motion tests, manual muscle testing, referred pain tests and imaging to be most important in the initial assessment of hamstring injuries. Magnetic resonance imaging (MRI) is preferred over ultrasonography and should take place within 3 days post-trauma. Important prognostic factors are injury grade, length of the muscle tear on MR images, MRI-negative injuries and trauma mechanism. CONCLUSIONS: Posture and gait inspection, inspection and palpation of muscle bellies, range of motion tests, manual muscle testing and referred pain tests within 2 days post-trauma were identified as the most relevant diagnostic factors. LEVEL OF EVIDENCE: Literature review and expert opinion, Level V.

The epidemiology of anterior cruciate ligament injury in football (soccer): a review of the literature from a gender-related perspective.

Football (soccer), the most popular sport worldwide, is associated with a high injury risk, and the knee joint is often affected. Several studies have found female players to be more susceptible to knee injury, anterior cruciate ligament (ACL) injury in particular, compared to their male counterparts. There is, however, some controversy regarding the magnitude of this risk increase and a few studies have found no differences. The influence of age and activity type on gender-related differences in injury risk is only scarcely investigated. In this paper, the literature reporting gender-specific ACL injury risk in football is reviewed. A literature search yielded 33 relevant articles that were included for review. These show that female players have a 2-3 times higher ACL injury risk compared to their male counterparts. Females also tend to sustain their ACL injury at a younger age than males, and a limiting factor in the existing literature is that age is not adjusted for in comparisons of ACL injury risk between genders. Furthermore, the risk increase in females is primarily evident during match play, but type of exposure is also rarely adjusted for. Finally, the studies included in this review share important methodological limitations that are discussed as a starting point for future research in the field.

Anterior cruciate ligament injury in elite football: a prospective three-cohort study.

Anterior cruciate ligament (ACL) injury causes long lay-off time and is often complicated with subsequent new knee injury and osteoarthritis. Female gender is associated with an increased ACL injury risk, but few studies have adjusted for gender-related differences in age although female players are often younger when sustaining their ACL injury. The objective of this three-cohort study was to describe ACL injury characteristics in teams from the Swedish men's and women's first leagues and from several European men's professional first leagues. Over a varying number of seasons from 2001 to 2009, 57 clubs (2,329 players) were followed prospectively and during this period 78 ACL injuries occurred (five partial). Mean age at ACL injury was lower in women compared to men (20.6 ± 2.2 vs. 25.2 ± 4.5 years, P = 0.0002). Using a Cox regression, the female-to-male hazard ratio (HR) was 2.6 (95% CI 1.4-4.6) in all three cohorts studied and 2.6 (95% CI 1.3-5.3) in the Swedish cohorts; adjusted for age, the HR was reduced to 2.4 (95% CI 1.3-4.2) and 2.1 (95% CI 1.0-4.2), respectively. Match play was associated with a higher ACL injury risk with a match-to-training ratio of 20.8 (95% CI 12.4-34.8) and 45 ACL injuries (58%) occurred due to non-contact mechanisms. Hamstrings grafts were used more often in Sweden than in Europe (67 vs. 34%, P = 0.028), and there were no differences in time to return to play after ACL reconstruction between the cohorts or different grafts. In conclusion, this study showed that the ACL injury incidence in female elite footballers was more than doubled compared to their male counterparts, but also that they were significantly younger at ACL injury than males. These findings suggest that future preventive research primarily should address the young female football player.

Football injuries during European Championships 2004-2005.

The risk of injury in football is high, but few studies have compared men's and women's football injuries. The purpose of this prospective study was to analyse the exposure and injury characteristics of European Championships in football and to compare data for men, women and male youth players. The national teams of all 32 countries (672 players) that qualified to the men's European Championship 2004, the women's European Championship 2005 and the men's Under-19 European Championship 2005 were studied. Individual training and match exposure was documented during the tournaments as well as time loss injuries. The overall injury incidence was 14 times higher during match play than during training (34.6 vs. 2.4 injuries per 1000 h, P < 0.0001). There were no differences in match and training injury incidences between the championships. Teams eliminated in the women's championship had a significantly higher match injury incidence compared to teams going to the semi-finals (65.4 vs. 5.0 injuries per 1000 h, P = 0.02). Non-contact mechanisms were ascribed for 41% of the match injuries. One-fifth of all injuries were severe with absence from play longer than 4 weeks. In conclusion, injury incidences during the European Championships studied were very similar and it seems thus that the risk of injury in international football is at least not higher in women than in men. The teams eliminated in the women's championship had a significantly higher match injury incidence than the teams going to the final stage. Finally, the high frequency of non-contact injury is worrying from a prevention perspective and should be addressed in future studies.

Analysis of proliferation, apoptosis and keratin expression in cultured normal and immortalized human buccal keratinocytes.

The current study was undertaken to analyse growth and differentiation-related functions of normal keratinocytes (NOK) and an SV40T-immortalized keratinocyte line (SVpgC2a) from buccal mucosa, viewing the latter cell line as a model of a dysplastic epithelium. Morphological and immunohistochemical assessments of organotypic epithelia generated from 10 or 17 d of culture showed three- to five-fold higher apoptotic and proliferative activity in SVpgC2a relative to NOK. Conditions with or without serum (up to 10%) did not significantly influence these parameters in NOK whereas serum supported proliferation of SVpgC2a. Both cell types showed basal expression of collagen IV and laminin 1, indicating basal lamina, as well as vimentin, indicating an activated, proliferative state. Reduced expression of keratin, including the non-keratinizing marker K13, was seen in SVpgC2a. Assessment of proliferative monolayer cultures by microarray showed that NOK transcribed tissue-specific keratins, but also the epidermal keratin K2a, several simple epithelial keratins and low levels of hair keratins. SVpgC2a transcribed keratins seen in epithelial dysplasia, and K2a and hair keratins, albeit at low level. Overall, the results implied aberrant apoptosis, proliferation and keratin expression in the immortalized state of SVpgC2a. Comparison of NOK and SVpgC2a under identical culture conditions may serve to model the progression from a normal to a pre-neoplastic state of buccal epithelium.