ACL injuries in men's professional football: a 15-year prospective study on time trends and return-to-play rates reveals only 65% of players still play at the top level 3 years after ACL rupture

Accuracy of the Region of Limb Stability in Predicting Risk for Lower Limb Injury

PURPOSE

This study aimed to determine whether a measure of lower limb segment stability derived from body-worn inertial measurement units can predict risk for lower limb musculoskeletal injury in Division I Collegiate Football Players (D1CFP).

METHODS

The region of limb stability (ROLS) values were collected in a cohort of D1CFP during preseason. ROLS is a measure of knee joint stability, defined by thigh and shank excursion (cm) in the anterior-posterior and medial-lateral direction during single limb stance. The ROLS symmetry index (SI) (%) is the ratio between lower limb ROLS values where 100% suggests absolute symmetry.

RESULTS

One-hundred and four D1CFP participated in this study and were divided into two groups: 1) no previous lower limb injury or no in-season injury (n = 70, "noninjured group") and 2) no previous lower limb injury, but in-season injury requiring surgery (n = 34, "injured group" group). The mean ± SD ROLS SI was 82.86% ± 14.75% and 65.58% ± 16.46% for the noninjured and injured group, respectively. Significant differences in ROLS SI were found between groups (P < 0.001). The ROLS SI demonstrated an area under the curve of 0.8 (P < 0.001; 95% confidence interval = 0.71-0.88) with an SE of 0.04, indicating that the ROLS SI has good predictive accuracy in detecting those healthy D1CFP at risk for lower limb injury resulting in surgery.

CONCLUSION

The ROLS SI was found to have good predictive accuracy in detecting individuals at risk for injury that were healthy and asymptomatic during preseason testing. Increase in thigh and shank excursions and/or decrease in SI between lower limbs may be a predictor of risk for future injury.

Individual hop analysis and reactive strength ratios provide better discrimination of ACL reconstructed limb deficits than triple hop for distance scores in athletes returning to sport

BACKGROUND

The triple hop for distance test commonly uses a limb symmetry index (LSI) 'pass' threshold of >90% for total hop distance following anterior cruciate ligament reconstruction (ACLR). However, understanding the manner in which athletes generate and dissipate forces during consecutive hops within the test may provide greater insight into residual limb deficits. The aim of the study was to examine reactive strength ratios (RSR) of individual hops during a triple hop test in a cohort of ACLR patients at discharge prior to return-to-sport.

METHODS

Twenty male athletes (24.6 ± 4.2 years; height 175.3 ± 10.2 cm; mass 73.6 ± 14.5 kg) completed the test on both non-operated and operated limbs. Total distance hopped, contact times, flight times and RSR were collected for each hop using a floor-level optical measurement system.

RESULTS

Significant, small to moderate between-limb differences (p < 0.05; d = 0.45-0.72) were shown for triple hop distance, flight time and RSR for each hop, with lower performance consistently displayed in the operated limb. Large, significant differences in RSR were evident between hops one and two on the operated limb (p < 0.05; d = 0.97). Despite 80% of participants achieving >90% LSI for total hop distance, less than 50% of participants reached the >90% LSI threshold for RSR.

CONCLUSIONS

Standardised LSI 'pass' thresholds (>90% LSI) for triple hop distance may mask residual deficits in reactive strength performance of operated limbs; therefore, more detailed analyses of individual hop performance may be warranted to enhance return to sport criteria following ACLR.

Return to Sports after ACL Reconstruction with Resection or Remnant-Preserving Technique

Objectives  To analyze the results of anterior cruciate ligament (ACL) reconstruction with remnant-preserving versus remnant-resecting technique, concerning the return to pre-lesion activity level.

Methods  The present retrospective cohort study has assessed adults > 18 years old who underwent ACL anatomical reconstruction between 2010 and 2014. The main outcomes assessed were: level of physical activity (4-point scale), sports participation rate, ACL rerupture defined as documented lesion requiring revision surgery and the numeric pain scale rate (NPSR).

Results  A total of 83 individuals were included in the study, with a mean age of 31.8 years old and follow-up mean time of 4.2 years after the surgery. A total of 34 patients underwent ACL reconstruction with remnant-preserving technique, and 49 without remnant preservation. No statistically significant difference was found between groups in all outcomes assessed: level of physical activity before the lesion and after the surgery, ACL rerupture rates and postoperative pain level. Subgroup analysis has shown a statistically significant decrease in the activity level in both groups. The most practiced sport was football; 72% of patients in the remnant group have resumed football activity versus 52.6% of the control group.

Conclusion  Based in these findings, the comparison between ACL reconstruction with remnant preserving technique and remnant resecting technique has shown no differences concerning the return to prelesion activity level.

Physical Performance Improves With Time and a Functional Knee Brace in Athletes After ACL Reconstruction

Background:

Athletes who return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR) often have reduced physical performance and a high reinjury rate. Additionally, it is currently unclear how physical performance measures can change during the RTS transition and with the use of a functional knee brace.

Purpose/Hypothesis:

The purpose of this study was to examine the effects of time since surgery (at RTS and 3 months after RTS) and of wearing a brace on physical performance in patients who have undergone ACLR. We hypothesized that physical performance measures would improve with time and would not be affected by brace condition.

Study Design:

Controlled laboratory study.

Methods:

A total of 28 patients who underwent ACLR (9 males, 19 females) completed physical performance testing both after being released for RTS and 3 months later. Physical performance tests included the modified agility t test (MAT) and vertical jump height, which were completed with and without a knee brace. A repeated-measures analysis of variance determined the effect of time and bracing on performance measures.

Results:

The impact of the knee brace was different at the 2 time points for the MAT side shuffle (P = .047). Wearing a functional knee brace did not affect any other physical performance measure. MAT times improved for total time (P < .001) and backpedal (P < .001), and vertical jump height increased (P = .002) in the 3 months after RTS.

Conclusion:

The present study showed that physical performance measures of agility and vertical jump height improved in the first 3 months after RTS. This study also showed that wearing a knee brace did not hinder physical performance.

Clinical Relevance:

Wearing a functional knee brace does not affect physical performance, and therefore a brace could be worn during the RTS transition without concern. Additionally, physical performance measures may still improve 3 months past traditional RTS, therefore justifying delayed RTS.

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.

Chaos and confusion with confidence: Managing fear of Re-Injury after anterior cruciate ligament reconstruction

OBJECTIVES

To explore strategies enabling competitive athletes to manage re-injury fears or anxieties, facilitating return to competitive sport following anterior cruciate ligament reconstruction (ACLR).

DESIGN

Qualitative study.

SETTING

University.

PARTICIPANTS

Ten athletes with ACLR within the last 5 years who had returned to competitive sport with a minimum 7/10 Tegner Activity score.

METHODS

Semi-structured interviews, recorded, transcribed and analysed using interpretive description.

RESULTS

Three main themes. "Driving reasons to return to sport" included the athletic identity, the competitive team spirit and commitment; "Preparation of body and mind" encompassed connectedness with health professionals, coaches, the sports team and family, graded exposure and progression of physical tasks, and psychological or cognitive skills to improve mental toughness; "Risk Acceptance" entailed situational risk analysis, problem solving, and avoidance of unacceptable risk and acceptance of risk and responsibility.

CONCLUSION

Participants described intrinsic and extrinsic motivators as drivers for rehabilitation. Interactions with therapists, coaches and team members enhanced confidence, supported by both physical rehabilitation and psychological influences. Psychological strategies were essential for several participants to return to sport. Graded sports exposure, leading towards total immersion in training and competition, appears important to manage re-injury fear following ACLR.

Systematic video analysis of ACL injuries in professional male football (soccer): injury mechanisms, situational patterns and biomechanics study on 134 consecutive cases

BACKGROUND

A few small studies have reported on the mechanisms of ACL injury in professional male football.

AIM

To describe the mechanisms, situational patterns and biomechanics (kinematics) of ACL injuries in professional male football matches.

METHODS

We identified 148 consecutive ACL injuries across 10 seasons of professional Italian football. 134 (90%) injury videos were analysed for mechanism and situational pattern, while biomechanical analysis was possible in 107 cases. Three independent reviewers evaluated each video. ACL injury epidemiology (month), timing within the match and pitch location at the time of injury were also reported.

RESULTS

59 (44%) injuries were non-contact, 59 (44%) were indirect contact and 16 (12%) were direct contact. Players were frequently perturbed immediately prior to injury. We identified four main situational patterns for players who suffered a non-contact or an indirect contact injury: (1) pressing and tackling (n=55); (2) tackled (n=24); (3) regaining balance after kicking (n=19); and (4) landing from a jump (n=8). Knee valgus loading (n=83, 81%) was the dominant injury pattern across all four of these situational patterns (86%, 86%, 67% and 50%, respectively). 62% of the injuries occurred in the first half of the matches (p<0.01). Injuries peaked at the beginning of the season (September-October) and were also higher at the end of the season (March-May).

CONCLUSIONS

88% of ACL injuries occurred without direct knee contact, but indirect contact injuries were as frequent as non-contact injuries, underlying the importance of mechanical perturbation. The most common situational patterns were pressing, being tackled and kicking.

The Effect of Proprioceptive Training on Directional Dynamic Stabilization

OBJECTIVES

Significant loss of playing time and the impact of treatment costs due to lower limb injury in football demonstrates a need for improved protocols for injury risk reduction. The aim of the present study is to assess the effect of a proprioceptive training program on the lower limb dynamic stability of elite footballers.

METHODS

A total of 16 elite premier league footballers were randomly allocated by matched pair design to a 8-week proprioception training group (group A, n = 8) or nontraining group (group B, n = 8), to determine the effect of this training over a 16-week period. Group A completed 8 weeks of bilateral proprioceptive training, 5 times per week for 10 minutes. The Biodex Stability System measures of overall stability index, anterior-posterior (A-P), and medial-lateral stability (M-L) at levels 8-6-4-1 were taken for both groups at baseline, 4, 8, and 16 weeks. Main effects of time, level of stability, and direction of stability were determined, with comparisons of effect made between the 2 groups.

RESULTS

The training group displayed significant differences for multidirectional stability at week 8 (P ≤ .05). The A-P stability within the training group displayed significant differences between baseline measures and 16 weeks (P > .05), with significant increases in scores displayed for M-L and A-P stability between weeks 8 and 16 (P ≤ .05), representing a detraining effect. No significant differences were detected at any time point for the nontraining group (P > .05).

CONCLUSIONS

Proprioceptive training over 8 weeks has a positive effect on all directions of stability. Greater declines in A-P stability were evident at 16 weeks when compared with M-L and overall stability index. Consideration must be given to the increased stability scores presented pretesting for A-P when compared with M-L. Findings of this work present implications for training design.

Injury burden differs considerably between single teams from German professional male football (soccer): surveillance of three consecutive seasons

PURPOSE

The purpose of this study was to analyse unique injury data of the national statutory accident insurance for the two highest divisions in German male football (Bundesliga and 2. Bundesliga) over three consecutive seasons regarding inter-season, inter-division and inter-team differences.

METHODS

This was a prospective observational open cohort study over the seasons 2014/2015, 2015/2016 and 2016/2017. Every acute injury that was registered by clubs or physicians with the German statutory accident insurance for professional athletes (VBG) as part of occupational accident reporting and that led to time loss and/or to medical attention, was included.

RESULTS

The complete sample consisted of 1449 players. The study covered 2663.5 player seasons with an observed match exposure of 69,058 h and a projected training exposure of 529,136 h. In total, 7493 injuries were included. The overall incidence rate was 12.5 (± 0.28) injuries per 1000 exposure hours, which translated into match and training rates of 47.0 (± 1.62) and 8.02 (± 0.24) injuries per 1000 h, respectively.

CONCLUSION

Findings of 2.7 injuries per player and season underline the need of effective preventive approaches. Higher injury incidences in seasons after international tournaments suggest an increasing risk of injury with increasing number of matches. However, large differences between the single teams from the same division indicate that a reduction in the injury burden is generally possible. Continuing the presented injury surveillance might be helpful to identify injury trends in the future and to evaluate the effectiveness of preventive approaches under real-life conditions.

LEVEL OF EVIDENCE

Level  II.

Australian Footballers Returning from Anterior Cruciate Ligament Reconstruction Later than 12 Months have Worse Outcomes

BACKGROUND

There is evidence that early return to competition post-anterior cruciate ligament (ACL) injury increases risk of re-injury.

AIMS

To compare subsequent ACL and other injury risks following ACL reconstruction for Australian Football League (AFL) players returning to competition at different times post-injury.

METHODS

AFL players returning from ACL reconstruction in the 1992-2014 seasons were divided into three groups based on return to competition time (< 10, 10-12 and > 12 months). Non-reconstructed injuries and artificial ligament reconstructions were excluded. Subsequent ACL injury rates were calculated based on time since injury and number of return matches played. Risk of other knee and hamstring muscle injuries was also calculated.

RESULTS

There were 233 ACL reconstructions that returned to play in the AFL during the time period under study and met our inclusion criteria. The per-game risk of subsequent ACL injury decreased with a log decay from 1.2 to 0.15% during the first 20 games back (R ² = 0.43). Players returning at > 12 months had higher overall percentage of future career games missed through subsequent ACL injuries (4.8% vs. 2.4%), and through all hamstring and knee injuries combined (12.6% vs. 8.4%) than players who returned at ≤ 12 months (both P < 0.001). Players returning at > 12 months had higher risk of knee cartilage (3.7%) and patella tendon (0.6%) injury than those returning at 10-12 months (1.5%, 0.1%, respectively).

CONCLUSION

Players returning from ACL reconstruction at greater than 12 months had significantly higher rates of future games missed through both subsequent ACL injuries and through all hamstring and knee injuries combined. It may be true that both early and late return to play lead to suboptimal outcomes compared to average return-to-play times.

Hamstring-to-Quadriceps Torque Ratios of Professional Male Soccer Players: A Systematic Review

Baroni, BM, Ruas, CV, Ribeiro-Alvares, JB, and Pinto, RS. Hamstring-to-quadriceps torque ratios of professional male soccer players: A systematic review. J Strength Cond Res 34(1): 281-293, 2020-The goal of this review was to determine the isokinetic hamstring-to-quadriceps (H/Q) torque ratios of professional male soccer players. Systematic searches were independently carried out by 2 researchers in 7 electronic databases. Only studies with teams from the first or second national leagues were included. From these studies, we extracted the players' H/Q conventional (concentric/concentric) and/or functional (eccentric/concentric) ratios. The initial search resulted in 2,128 articles that were filtered to 30 articles (1,727 players) meeting the inclusion criteria. The H/Q conventional ratio was assessed in 27 studies (1,274 players), whereas the H/Q functional ratio was assessed in 15 studies (1,082 players). The H/Q conventional ratio mean scores of professional male soccer players were close to 60% when tested at low to intermediate angular velocities (12°·s = 52 ± 7%; 30°·s = 52 ± 8%; 60°·s = 65 ± 12%; 90°·s = 57 ± 6%; 120°·s = 65 ± 16%; 180°·s = 67 ± 17%) and around 70-80% at fast angular velocities (240°·s = 80 ± 40%; 300°·s = 70 ± 15%; 360°·s = 80 ± 13%). The H/Q functional ratio mean scores of professional male soccer players were close to 80% at 60°·s (79 ± 19%), around 100-130% at intermediate to fast angular velocities (120°·s = 127 ± 42%; 180°·s = 96 ± 19%; 240°·s = 109 ± 22%; 300°·s = 123 ± 18%), and near or above 130% when angular testing velocities were mixed (eccentric hamstring < concentric quadriceps; 30/240°·s = 132 ± 26%; 60/180°·s = 129 ± 20%; 60/240°·s = 153 ± 30%). In conclusion, considering the tested isokinetic angular velocity, professional male soccer players do not meet the traditional reference landmarks used to assess the strength balance between quadriceps and hamstring muscles (i.e., 60 and 100% for H/Q conventional and functional ratios, respectively), which supports a need for specific reference values according to the angular velocity selected for testing H/Q torque ratios.

Return to play after three ipsilateral anterior cruciate ligament reconstructions in an elite soccer player: A case report

INTRODUCTION

Despite the reasonable success of ACL reconstruction, some athletes are not able to regain the level of play they once had.

PRESENTATION OF CASE

Here, we report the case of a 32-year-old male professional soccer player who sustained an ACL injury in his right knee. The patient had a history of two prior ipsilateral ACL injuries, which was reconstructed with ipsilateral hamstring autograft (first surgery) and ipsilateral patellar tendon autograft (revision surgery). Imaging examination revealed a small narrowing of the medial femoro-tibial compartment, a complete ACL rupture, partial medial meniscectomy, small cartilage lesions in the medial condyle, a 7° varus knee, an enlarged tibial tunnel, and a femoral tunnel positioned high above the intercondylar roof. A one-step re-revision surgery using a fresh-frozen, cadaveric, non-irradiated Achilles tendon allograft was planned. After surgery, physiotherapy was conducted once per day during 4 months. The patient started running at the 6^th month, and returned to full training 8 months after surgery. The player returned to full competitive play 9 months after surgery and has been competing for the last 36 months at the highest level of play without any limitation, inflammation, pain, or perception of instability.

CONCLUSION

In professional sports, when re-revision ACL reconstruction is indicated and the patient expects to return to competition, surgery should not be delayed. In these cases, the usefulness of Achilles tendon allograft should be taken into consideration for re-revision ACL reconstruction.

High Risk of Further Anterior Cruciate Ligament Injury in a 10-Year Follow-up Study of Anterior Cruciate Ligament-Reconstructed Soccer Players in the Swedish National Knee Ligament Registry

PURPOSE

To follow up on soccer players 10 years after a primary anterior cruciate ligament (ACL) reconstruction to find out how many players returned to play soccer, what influenced their decision, and if there are any differences in additional ACL injuries (graft failure and/or contralateral ACL injury) between those who returned to play and those who did not.

METHODS

The study cohort consists of 1661 soccer players from the Swedish National Knee Ligament Registry. A questionnaire was sent to each player regarding their return to play and additional knee injuries that may have occurred 10 years after their primary ACL. The results are based on the 684 responders. Data such as age, sex, surgical procedural data, associated injuries, patient-reported outcome measures, and additional knee surgeries were collected from the registry.

RESULTS

In this study, 51% returned to play soccer. For those who did not return to play, the primary reason was knee related (65.4% of the cases). The most common knee-related reasons for not returning were pain and/or instability (50%; n = 109), followed by fear of reinjury (32%; n = 69). Players who return to soccer have a significantly higher risk of additional ACL injury. Of the players who returned to play soccer, 28.7% (odds ratio [OR] 2.3, P < .001) had additional ACL injury, 9.7% (OR 2.9, P < .001) had a graft failure and 20.6% (OR 2.1, P < .001) had a contralateral ACL injury.

CONCLUSIONS

Players that return to soccer have a significantly higher risk of sustaining further ACL injury. Only half of the soccer players return to play after ACL reconstruction, and in two-thirds of those who did not return, the reason was knee related. The high risk of sustaining additional knee injury is of serious concern to the player's future knee health and should be considered when deciding on a return to play.

LEVEL OF EVIDENCE

Level III retrospective case-control study.

Epidemiology of Anterior Cruciate Ligament Injury in Italian First Division Soccer Players

BACKGROUND

The burden of anterior cruciate ligament (ACL) injury in professional soccer players is particularly relevant as it represents a potentially career-threatening injury.

HYPOTHESIS

Our hypotheses were that (1) injury incidence rate would be similar to that reported in the literature, (2) we would identify a uniform distribution of the injuries along the season, and (3) injury incidence rate would be similar in high-ranked and lower ranked teams, based on final placement in the league.

STUDY DESIGN

Descriptive epidemiological study.

LEVEL OF EVIDENCE

Level 4.

METHODS

Professional male soccer players participating in the Serie A championship league in 7 consecutive seasons (2011-2012 to 2017-2018) were screened to identify ACL injuries through the online football archive transfermarkt.com . Exposure in matches and training were calculated.

RESULTS

There were 84 ACL injuries found (mean player age, 25.3 ± 4.2 years). Overall, 25% of ACL injuries were reruptures (15%) or contralateral injuries (10%). ACL incidence rate was 0.4215 per 1000 hours of play during Serie A matches, 0.0305 per 1000 hours of training (rate ratio [RR], 13.8; 95% CI, 8.4-22.7; P < 0.0001), and 0.0618 per 1000 hours of total play. Injury distribution had a bimodal peak, with the highest number of events in October and March. Alternatively, training injuries peaked in June and July. A significantly higher incidence rate was found for the teams ranked from 1st to 4th place compared with those ranked 5th to 20th (0.1256 vs 0.0559 per 1000 hours of play; RR, 2.2; 95% CI, 1.4-3.6; P = 0.0003). A similar finding was found for injury incidence proportion (3.76% vs 1.64%; P = 0.0003).

CONCLUSION

The overall incidence rate of ACL injuries in Italian Serie A was 0.062 per 1000 hours, with a 14-fold risk in matches compared with training. Relevantly, 25% were second injuries. Most injuries occurred in October and March, and an almost 2-fold incidence rate and incidence proportion were noted in those teams ranked in the first 4 positions of the championship league.

CLINICAL RELEVANCE

Knowing the precise epidemiology of ACL injury in one of the most competitive professional football championship leagues could help delineate fields of research aimed to investigate its risk factors.

Is restricted hip movement a risk factor for anterior cruciate ligament injury?

Restricted hip movement along with femoroacetabular impingement (FAI) has been reported to be an important risk factor in anterior cruciate ligament (ACL) injury. We performed a literature review assessing the evidence that FAI, or restricted hip movement, contributes to the likelihood of sustaining an ACL injury to provide an evidence-based and comprehensive update on the relationship between these pathologies. Studies were divided into three categories: clinical studies, radiological studies and cadaveric studies. Clinical studies primarily assessed the limitations to hip movement in patients with ACL injury, and numerous studies of this kind have demonstrated a relationship between restricted movement and ACL injury. Radiological studies have been able to demonstrate a higher number of bony hip abnormalities in patients with ACL injury. However, due to variable results within these studies, it is unclear which kinds of bony abnormality are specifically associated with an increased risk of ACL injury. Cadaveric studies have demonstrated that peak ACL relative strain was inversely related to the range of internal rotation of the femur, thus providing a potential mechanism for this relationship. In conclusion, clinical and radiological studies have established a correlation between restricted hip and ACL injury, but have been unable to demonstrate an increased risk of future ACL injury in individuals with restricted hip movement. Future prospective cohort studies are necessary to confirm this. Additionally, these findings highlight the need for a thorough clinical assessment of the hip when assessing patients with an ACL injury.

Perspectives in football medicine

The high injury rate among men's professional football players is well-known. Therefore, the Union of European Football Associations (UEFA) launched an injury study already in 2001. This study, the UEFA Elite Club Injury Study (ECIS), currently includes data from a total of 51 clubs from 18 European countries with more than 14,000 registered injuries. With the 21^st World Cup (WC) in Russia just around the corner, we have from our study identified a higher match injury rate and a higher proportion of severe injuries in the European Championships compared to the preceding club competitive seasons. Moreover, we have also recently showed that the muscle injury rate is higher when players are given a recovery window of five days or less between two matches. Considering the congested match schedule of the upcoming WC, it is therefore likely that injuries and fatigue once again will be a topic of discussion this summer.

The Effects of Six-Weeks Change of Direction Speed and Technique Modification Training on Cutting Performance and Movement Quality in Male Youth Soccer Players

Cutting manoeuvres are important actions associated with soccer performance and a key action associated with non-contact anterior cruciate ligament injury; thus, training interventions that can improve cutting performance and movement quality are of great interest. The aim of this study, therefore, was to determine the effects of a six-week change of dire[ction (COD) speed and technique modification training intervention on cutting performance and movement quality in male youth soccer players (U17s, n = 8) in comparison to a control group (CG) (U18s, n = 11) who continued ‘normal’ training. Cutting performance was assessed based on completion time and COD deficit, and the field-based cutting movement assessment score (CMAS) qualitative screening tool was used to assess cutting movement quality. Significant main effects for time (pre-to-post changes) (p ≤ 0.041, η² = 0.224–0.839) and significant interaction effects of time and group were observed for cutting completion times, COD deficits, and CMASs. Improvements in completion time (p < 0.001, g = 1.63–1.90, −9% to −11% vs. −5% to 6%) and COD deficit (p ≤ 0.012, g = −1.63 to −2.43, −40–52% vs. −22% to −28%) for the COD intervention group (IG) were approximately two-times greater than the CG. Furthermore, lower CMASs (i.e., improved cutting movement quality) were only observed in the IG (p ≤ 0.025, g = −0.85 to −1.46, −23% to −34% vs. 6–19%) compared to the CG. The positive changes in CMASs were attributed to improved cutting technique and reduced incidences of high-risk deficits such as lateral trunk flexion, extended knee postures, knee valgus, hip internal rotation, and improved braking strategies. The results of this study indicate that COD speed and technique modification training, in addition to normal skills and strength training, improves cutting performance and movement quality in male youth soccer players. Practitioners working with male youth soccer players should implement COD speed and technique modification training to improve cutting performance and movement quality, which may decrease potential injury-risk.

Case Study: Muscle Atrophy, Hypertrophy, and Energy Expenditure of a Premier League Soccer Player During Rehabilitation From Anterior Cruciate Ligament Injury

Maintaining muscle mass and function during rehabilitation from anterior cruciate ligament injury is complicated by the challenge of accurately prescribing daily energy intakes aligned to energy expenditure. Accordingly, we present a 38-week case study characterizing whole body and regional rates of muscle atrophy and hypertrophy (as inferred by assessments of fat-free mass from dual-energy X-ray absorptiometry) in a professional male soccer player from the English Premier League. In addition, in Week 6, we also quantified energy intake (via the remote food photographic method) and energy expenditure using the doubly labeled water method. Mean daily energy intake (CHO: 1.9-3.2, protein: 1.7-3.3, and fat: 1.4-2.7 g/kg) and energy expenditure were 2,765 ± 474 and 3,178 kcal/day, respectively. In accordance with an apparent energy deficit, total body mass decreased by 1.9 kg during Weeks 1-6 where fat-free mass loss in the injured and noninjured limb was 0.9 and 0.6 kg, respectively, yet, trunk fat-free mass increased by 0.7 kg. In Weeks 7-28, the athlete was advised to increase daily CHO intake (4-6 g/kg) to facilitate an increased daily energy intake. Throughout this period, total body mass increased by 3.6 kg (attributable to a 2.9 and 0.7 kg increase in fat free and fat mass, respectively). Our data suggest it may be advantageous to avoid excessive reductions in energy intake during the initial 6-8 weeks post anterior cruciate ligament surgery so as to limit muscle atrophy.

High return to competition rate following ACL injury - A 10-year media-based epidemiological injury study in men's professional football

Ruptures of the anterior cruciate ligament (ACL) typically occur in professional football and epidemiological data about longitudinal injury development is needed. This practice-driven investigation of media-derived ACL data provides information about professional football over 10 years. Injury registration was based on "kicker" sports magazine information that have been recorded over one decade in a standardized manner. Only ACL ruptures in the first German football league were included when they could be verified by a second reliable source. Level of evidence: III. Fifty-seven primary ACL ruptures were verified in the first German football league during the seasons 2007/2008 to 2016/2017. Among them, six re-injuries were found. Mean age at the time of injury was 24.8 years (SD 3.8). 31% (n = 20) of ACL ruptures occurred at the beginning of the season in August or September (p = 0.02). Mean time of RTC after primary ACL ruptures was 226.7 days (SD: 93.5) and 245.6 days (SD: 45.4) after re-injury. Although 62 (98%) players returned to football after injury and only one player immediately finished his career, 54.9% of the affected individuals played 3 years after the ACL rupture in the same league. ACL ruptures lead to longer absence than 7 months from football but does not give reason for immediate career-ending. The decrease in playing level after 3 years illustrate the serious consequences of ACL ruptures in football. Media-based injury reports may provide interesting information.

Adjustable buttons for ACL graft cortical fixation partially fail with cyclic loading and unloading

PURPOSE

Despite good initial pullout strength, it is unclear whether adjustable button (AB) devices for anterior cruciate ligament (ACL) soft-tissue graft fixation, which are based on the Chinese finger trap technique, resist cyclic loading. Furthermore, they have never been tested in a cyclic protocol including complete unloading. It was hypothesized, that the displacement of AB devices with the Chinese finger trap technique would be greater than that of continuous suture loop devices and other available AB mechanisms in a cyclic loading with complete unloading protocol.

METHODS

ACL reconstruction was performed in a porcine knee model using three different types of cortical fixation devices: two different AB devices that use the Chinese finger trap design, one AB device that uses a locked suture loop mechanism and two different continuous loop devices as control groups (n = 40). Specimens were mounted in a material-testing machine (Instron Inc.) that permitted 2500 loading and complete unloading cycles to a maximum of 250 N, as well as continuous elongation recording. A one-way ANOVA was performed for statistical analysis.

RESULTS

The displacement of ABs with a Chinese finger trap loop (mean 8.1; SD 1.5 mm and mean 6.1; SD 1.4 mm) was significantly greater than that of AB with a locked suture loop (mean 4.7; SD 1.0 mm; p < 0.05) and devices with a continuous loop (mean 4.1; SD 0.5 mm and mean 4.4, SD 0.3 mm; p < 0.01). No significant differences were detected between the ABs with a locked suture loop and the continuous loops.

CONCLUSION

Cyclic loading and unloading of AB using the Chinese finger trap technique leads to significantly greater construct lengthening compared with other devices. Complete unloading of the ACL is very likely to occur during rehabilitation after ACL reconstruction. Lengthening of the AB device due to cyclic loading might be a potential mode of failure of the ACL graft fixation. Therefore, when using an AB femoral fixation technique, a locked suture loop design or a careful rehabilitation protocol should be considered.

On-field Rehabilitation Part 2: A 5-Stage Program for the Soccer Player Focused on Linear Movements, Multidirectional Movements, Soccer-Specific Skills, Soccer-Specific Movements, and Modified Practice

This paper is part 2 of a 2-part series aimed at discussing the key elements of on-field rehabilitation training. In part 1, we described 4 pillars underpinning high-quality on-field rehabilitation: (1) restoring movement quality, (2) physical conditioning, (3) restoring sport-specific skills, and (4) progressively developing chronic training load. In part 2, we describe how the pillars contribute to a 5-stage on-field rehabilitation program to help injured players transition to team practice and match play. We use the example of a soccer player with ambitions to return to sport after anterior cruciate ligament reconstruction. The program moves through 5 field-based training stages: (1) linear movement, (2) multidirectional movement, (3) soccer-specific technical skills, (4) soccer-specific movement, and (5) practice simulation. The staged program is research based and facilitates communication, planning, control, and safety in return to sport following long-term injury. J Orthop Sports Phys Ther 2019;49(8):570-575. doi:10.2519/jospt.2019.8952.

Eighty-two per cent of male professional football (soccer) players return to play at the previous level two seasons after Achilles tendon rupture treated with surgical repair

OBJECTIVE

To evaluate the time to return to playing following acute Achilles tendon rupture (ATR) and surgical repair in professional male football (soccer) players.

METHODS

Professional male football (soccer) players who sustained an ATR and underwent surgical repair were identified through internet-based injury reports from January 2008 to August 2018. Only League 1 and 2 players with injuries who had at least 1 year of follow-up from the search date were included. Injury history and time to return to play were retrieved from the public platform transfermarkt.com. For athletes who competed for at least two seasons after returning to play, re-ruptures and number of matches played were reported.

RESULTS

118 athletes (mean age 27.2±7.2 years) were included. 113 (96%) returned to unrestricted practice after a mean of 199±53 days, with faster recovery in players involved in national teams. Return to competition was after a mean of 274±114 days. In the 76 athletes with at least two seasons of follow-up, 14 (18%) did not compete at the pre-injury level during the two seasons following the index injury. Six players (8%) sustained a re-rupture within the first two seasons after return to play; four re-ruptures were in footballers who returned to play <180 days after injury. Age >30 years and re-ruptures had higher odds ratios of not returning to the same level of play.

CONCLUSIONS

96% of professional male football players who underwent surgery to repair an ATR returned to unrestricted practice and then competition after an average time of 7 and 9 months, respectively. However, 18% did not return to the same level of play within the two seasons following their return, with a higher risk in those experiencing a re-rupture.

Isokinetic eccentric training is more effective than constant load eccentric training for quadriceps rehabilitation following anterior cruciate ligament reconstruction: a randomized controlled trial

OBJECTIVE

To compare the effects of conventional (constant load) eccentric training and isokinetic eccentric training on quadriceps muscle mass, strength and functional performance in recreational athletes following anterior cruciate ligament (ACL) reconstruction.

METHODS

Thirty recreational male athletes (25 years old) undergoing ACL reconstruction received a standard rehabilitation program. Volunteers were randomized to conventional group (CG; n = 15) or isokinetic group (IG; n = 15) to be engaged in a 6-week (2 sessions/week) quadriceps eccentric training program at the extensor chair or at the isokinetic dynamometer, respectively. Assessments of quadriceps muscle mass (through magnetic resonance imaging), strength (through isokinetic dynamometry) and self-aware functionality (through questionnaire) were performed before and after the training programs. Single leg hop test performance was assessed only at post-training evaluation.

RESULTS

IG had significantly higher improvements than CG (p < 0.05) for all muscle mass outcomes (+17-23% vs. +5-9%), as well as for isometric (+34% vs. +20%) and eccentric (+85% vs. +23%) peak torques. There was no between-group difference (p > 0.05) for concentric peak torque, Lysholm score, and single leg hop test.

CONCLUSION

Isokinetic eccentric training promotes greater responses than conventional eccentric training on quadriceps muscle mass and strength of recreational athletes following ACL reconstruction.

Early or delayed anterior cruciate ligament reconstruction: Is one superior? A systematic review and meta-analysis

Background

Anterior cruciate ligament (ACL) reconstruction is a rapidly developing orthopaedic field and an area of notable clinical equipoise. The optimal timing of surgery in an acute (< 3 weeks) or delayed (≥ 3 weeks) time frame remains unresolved with a 2010 meta-analysis concluding no difference between these two groups across multiple outcomes. In an era of evidence-based medicine, surgeons are still basing their decisions on when to operate on little more than anecdotal evidence and personal preference. Clear guidance is required to determine whether the timing of surgery can optimise outcomes in this largely young and active patient cohort.

Methods

A systematic literature search was performed in January 2018 of Embase, Medline and OpenGrey in accordance with (PRISMA) guidelines. A total of 658 articles were retrieved, with 6 suitable for inclusion, covering 576 ACL reconstructions. Four meta-analyses were performed assessing subjective measures of Tegner activity scale and Lysholm score, and objective measures of arthroscopically identified meniscal and chondral injury. Additional relevant outcome measures underwent narrative review. Study bias was assessed and reported using the Downs and Black checklist.

Results

A statistically significant difference of 0.39 points was found on the Tegner activity scale in favour of early surgery within 3 weeks (RR 0.39, CI 0.10, 0.67, p = 0.008). No statistically difference was found between groups for the patient-reported Lysholm score (RR − 0.18, CI − 2.40, 2.05, p = 0.17). There was no statistically significant difference between groups for intra-operative findings of meniscal lesions (RR 0.84, CI 0.66, 1.08, p = 0.17). A trend towards significance was observed for the incidence of chondral lesions in the early surgery group (RR 0.56, CI 0.31, 1.02, p = 0.06). All the studies were rated either fair or good on the Downs and Black checklist with no study excluded due to bias.

Conclusions

Although there was a statistically significant result for the Tegner activity scale in favour of early surgery, the magnitude of the effect is unlikely to translate into any clinically meaningful difference. At present, there remains no clear evidence to determine superiority of acute/early or delayed reconstruction of a ruptured anterior cruciate ligament. Further research through methodologically robust randomised controlled trials or through the UK National Ligament Registry  may help to provide clearer guidance.

Combined Anterior Cruciate and Anterolateral Ligament Reconstruction in the Professional Athlete: Clinical Outcomes From the Scientific Anterior Cruciate Ligament Network International Study Group in a Series of 70 Patients With a Minimum Follow-Up of 2 Years

PURPOSE

To evaluate clinical outcomes in professional athletes after combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction at a minimum follow-up of 2 years.

METHODS

A retrospective analysis of prospectively collected data from the Scientific Anterior Cruciate Ligament Network International (SANTI) Study Group database was performed. All professional athletes who underwent primary combined ACL and ALL reconstruction between January 2011 and March 2016 were included. Patient assessment included physical examination, pre- and postoperative subjective and objective International Knee Documentation Committee (IKDC), Tegner activity scale, and Lysholm scores.

RESULTS

Seventy-two professional athletes underwent primary ACL and ALL reconstruction; 70 (97%) were available, with a mean follow-up of 3.9 years (range, 2-7). The preoperative side-to-side anteroposterior laxity difference was 7.1 ± 1.4 mm, and this decreased significantly after surgery to 0.4 ± 0.9 mm (P < .0001). Pivot-shift grade evolved from 16 grade I (22.8%) and 54 grade II or III (77.2%) preoperatively, to 66 absent pivot shift (94.3%) and 4 grade I (5.7; P < .001). By 1-year postoperatively, 60 athletes (85.7%) returned to professional sport, with a mean time interval of 7.9 months (range, 5-12). Preoperatively, the mean subjective IKDC was 56.1 ± 12.3, the Lysholm score was 48.4 ± 12.5, and the Tegner score was 9.3 ± 1. At final follow-up, the mean subjective IKDC was 90.5 ± 7.6 (P < .0001), the Lysholm score was 94.4 ± 7.5 (P < .0001), and the Tegner score was 8.8 ± 1.5 (P < .004). The objective IKDC evolved from 39 grade C (55.7%) and 31 grade D (44.3%) preoperatively to 65 grade A (92.9%) and 5 grade B (7.1%) (P < .0001). Eleven Patients (15,7%) underwent a subsequent ipsilateral reoperation including 4 (5.7%) revision ACL reconstructions. The risk of graft rupture was significantly higher in female patients (13.6% vs 2.1% in male patients; P = .048).

CONCLUSIONS

Combined ACL and ALL reconstruction is associated with excellent outcomes in professional athletes with respect to graft rupture rates, return to sport, knee stability, and reoperation rates after injury.

LEVEL OF EVIDENCE

Level IV, case series.

Psychological Readiness to Return to Sport Is Associated With Second Anterior Cruciate Ligament Injuries

BACKGROUND

Psychological responses after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) have been identified as predictors of return to sport but have not been investigated in relation to further injury.

PURPOSE/HYPOTHESIS

To determine whether psychological readiness to return to sport is associated with second ACL injury. It was hypothesized a priori that at both preoperative and 12-month postoperative time points, patients who sustained a second ACL injury would have lower psychological readiness than patients who did not have a second injury.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients who had a primary ACLR procedure between June 2014 and June 2016 completed the ACL-Return to Sport after Injury (ACL-RSI) (short version) scale before their ACLR and repeated the scale at 12 months after surgery to assess psychological readiness to return to sport. Patients were followed for a minimum of 2 years (range, 2-4 years) after surgery to determine further injury. The primary outcome was the relationship between ACL-RSI scores and the incidence of second ACL injury.

RESULTS

In 329 patients who returned to sport after ACLR, 52 (16%) sustained a second ACL injury. No difference in psychological readiness was observed at the preoperative time point, but patients who sustained a second injury trended toward lower psychological readiness at 12 months compared with noninjured patients (60.9 vs 67.2 points; P = .11). Younger (≤20 years) patients with injury had significantly lower psychological readiness to return to sport than young noninjured patients (60.8 vs 71.5 points; P = .02), but no difference was found in older patients (60.9 vs 64.6 points; P = .58). In younger patients, receiver operating characteristic curve analysis revealed a cutoff score of 76.7 points with 90% sensitivity to identify younger patients who sustained a second ACL injury.

CONCLUSION

Younger patients with lower psychological readiness are at higher risk for a second ACL injury after return to sport.

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.

The negative impact of anterior cruciate ligament reconstruction in professional male footballers

BACKGROUND

Soccer is one of the most common international sports in which ACL injuries occur, with previous studies reporting high return-to-play rates following ACL reconstruction (ACLR). Return-to-play analysis fails to take into consideration how effective a player remains once returning to competition. The aims of this study are to provide a large-scale international analysis of return-to-play and player performance statistics among professional soccer athletes following ACLR.

METHODS

Using publicly available sources, professional soccer athletes who have undergone ACLR between the 1996 and 2015 seasons were identified. Player metrics including statistical performance, recovery time, and return-to-play rates were analyzed both before and after reconstruction. Furthermore, player performance statistics during each of three consecutive seasons post-ACLR were compared.

RESULTS

A total of 176 athletes who underwent ACLR were included in this study. The return-to-play rate was 93.2% (164 athletes). Cumulative post-surgical statistical analysis of ACLR players demonstrated fewer games/season, minutes/season, minutes/game, goals/season, and more fouls/season following ACLR (p < 0.04). Analysis of player performance statistics suggests that athletes do not return to their baseline number of games/season and minutes/game until two and three seasons post-ACLR, respectively. At three seasons post-ACLR, athletes are still starting fewer games/season and scoring fewer goals/90 min (p < 0.04).

CONCLUSION

Return-to-play rate is high following ACLR; however, athletes exhibit poorer statistical performance, especially in the first few seasons upon return. Our data shows that athletes continue to start fewer games/season and score fewer goals/90 min at three seasons post-ACLR.

National injury prevention measures in team sports should focus on knee, head, and severe upper limb injuries

PURPOSE

To examine acute injuries in licensed floorball, football, handball, and ice hockey players in all ages nationwide in Sweden, and to identify the most common and severe injuries in each body location and recommend injury prevention measures.

METHODS

Using national sport insurance data from years 2006-2015 was the incidence and proportion of acute injuries, and injuries leading to permanent medical impairment (PMI), calculated in the four team sports. The most common injury type and injured body part was identified, with a particular focus of the severe injuries. Comparison between sexes was made.

RESULTS

In total, there were 92,162 registered injuries in all sports together. Knee injuries were most common, and also had the highest incidence of PMI, in all ball sports and in female ice hockey players. In male ice hockey, the most common injury was a dental and face injury, and PMI injuries were mostly in the shoulder. The most severe PMI injuries were rare and most often a face/eye injury in male floorball and ice hockey, a concussion in female ice hockey, and a knee injury in female floorball, and in both sexes in football and handball.

CONCLUSIONS

To achieve the greatest impact in reducing the adverse effects of acute sport injuries nationwide in Sweden, preventive measures should focus on knee injuries in all the investigated team sports. The severe head/face and upper limb injuries also need attention. Protective equipment, neuromuscular training programs, rules enforcements, and fair-play interventions may reduce the incidence of injuries.

Female Soccer Players With Anterior Cruciate Ligament Reconstruction Have a Higher Risk of New Knee Injuries and Quit Soccer to a Higher Degree Than Knee-Healthy Controls

BACKGROUND

Many patients with anterior cruciate ligament (ACL) reconstruction who return to sport suffer new ACL injuries or quit sports soon after returning.

PURPOSE

To prospectively follow a cohort of female soccer players with primary unilateral ACL reconstruction and matched knee-healthy controls from the same soccer teams to compare (1) the rate of new traumatic and nontraumatic knee injuries and other injuries, (2) the proportion of players who quit soccer, and (3) player-reported activity level and satisfaction with activity level and knee function.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 117 active female soccer players (mean ± SD age, 19.9 ± 2.5 years) 18.9 ± 8.7 months after ACL reconstruction and 119 knee-healthy female soccer players (19.5 ± 2.5 years) matched from the same teams were prospectively followed for 2 years for new knee injuries, other injuries, soccer playing level, activity level according to the Tegner Activity Scale, and satisfaction with activity level and knee function.

RESULTS

Players with ACL reconstruction had a higher rate of new ACL injuries (n = 29 vs 8; 19 vs 4 per 100 player years; rate ratio [RR], 4.82; 95% CI, 2.20-10.54; P < .001), other traumatic knee injuries (29 vs 16 per 100 player years; RR, 1.84; 95% CI, 1.16-2.93; P < .01), and nontraumatic knee injuries (33 vs 9 per 100 player years; RR, 3.62; 95% CI, 2.11-6.21; P < .001) as compared with controls. There was no difference in the rate of other (not knee) injuries (43 vs 48 per 100 player years; RR, 0.90; 95% CI, 0.65-1.23; P = .494). During the 2-year follow-up, 72 (62%) players with ACL reconstruction quit soccer, as opposed to 43 (36%) controls ( P = .001). The median Tegner Activity Scale score decreased in both groups ( P < .001) but more for the ACL-reconstructed group ( P < .015).

CONCLUSION

Female soccer players with ACL reconstruction had nearly a 5-fold-higher rate of new ACL injuries and a 2- to 4-fold-higher rate of other new knee injuries, quit soccer to a higher degree, and reduced their activity level to a greater extent as compared with knee-healthy controls.

A Nationwide Follow-up Survey on the Effectiveness of an Implemented Neuromuscular Training Program to Reduce Acute Knee Injuries in Soccer Players

Background:

A cruciate ligament (CL) injury is a severe injury in soccer. Neuromuscular training programs have a well-documented preventive effect, but there are few studies on the effectiveness of such a program at a national level. The Swedish Knee Control Program (KCP) was found to be effective in preventing CL injuries in youth female soccer players. The KCP was implemented nationwide in Sweden in 2010.

Purpose:

To evaluate the effectiveness of the Swedish KCP in reducing acute knee injuries in soccer players at a nationwide level.

Study Design:

Descriptive epidemiology study.

Methods:

All licensed soccer players in Sweden are covered by the same insurance company. Using this insurance database, around 17,500 acute knee injuries that were reported to the insurance company between 2006 and 2015 were included in the study. By matching the number of licensed soccer players with the number of reported injuries each year, the annual incidence of knee and CL injuries was able to be calculated. To evaluate the spread of the KCP nationally, a questionnaire was sent to all 24 Swedish district football associations (FAs) with questions regarding KCP education. The number of downloads of the KCP mobile application (app) was obtained.

Results:

The incidence of CL injuries decreased during the study period for both male (from 2.9 to 2.4 per 1000 player-years) and female players (from 4.9 to 3.9 per 1000 player-years). The overall incidence of knee injuries decreased in both male (from 5.6 to 4.6 per 1000 player-years) and female players (from 8.7 to 6.4 per 1000 player-years). Comparing before and after the nationwide implementation of the KCP, there was a decrease in the incidence of CL injuries by 6% (rate ratio [RR], 0.94 [95% CI, 0.89-0.98]) in male players and 13% (RR, 0.87 [95% CI, 0.81-0.92]) in female players and a decrease in the incidence of knee injuries by 8% (RR, 0.92 [95% CI, 0.89-0.96]) and 21% (RR, 0.79 [95% CI, 0.75-0.83]), respectively (P < .01 for all). This trend corresponded to a reduction of approximately 100 CL injuries each year in Sweden. A total of 21 of 24 district FAs held organized KCP educational courses during the study period. The percentage of district FAs holding KCP courses was between 46% and 79% each year. There were 101,236 downloads of the KCP app.

Conclusion:

The KCP can be considered partially implemented nationwide, and the incidence of knee and CL injuries has decreased in both sexes at a nationwide level.

Lower extremity osteoarthritis is associated with lower health-related quality of life among retired professional footballers

OBJECTIVE

The objective of the current study was to explore whether retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than those without OA or current professional footballers.

METHODS

An observational study based on a cross-sectional design by means of questionnaires was conducted. Participants were retired and current professional footballers recruited by the World Players' Union (FIFPro). Information about lower extremity OA (clinically diagnosed by a medical professional) was gathered, while health-related quality of life (Global Physical Health and Global Mental Health scores) was assessed through a validated scale.

RESULTS

A total of 396 retired and 361 current professional footballers were included in the analyses (response rate of 54%). The group of retired professional footballers was on average 36 years old, and they had competed in professional football for 11 years (retired for 5 years). The group of current professional footballers was on average 25 years old, and they had been active in professional football for 7 years. Within the group of retired professional footballers, prevalence of lower extremity OA was 33%. Both Global Physical Health and Global Mental Health scores among retired professional footballers with lower extremity OA were significantly lower than among retired players without OA and current players, but these scores were nearly similar to the norm for the general population (regardless the presence of OA or not).

CONCLUSIONS

Health-related quality of life among retired professional footballers with lower extremity OA was significantly lower than among retired players without OA and current players but nearly similar to the norm for the general population (regardless the presence of OA or not). A rational recommendation is that a support measure such as the After Career Consultation should be introduced among retired professional footballers in order to empower their sustainable health and quality of life, focussing especially on the prevention of the occurrence or worsening of lower extremity OA.

ACL injury incidence, severity and patterns in professional male soccer players in a Middle Eastern league

Aim

To ascertain ACL injury incidence, severity (injury burden) and patterns (contact/non-contact and reinjuries) in a professional male football league in the Middle East over five consecutive seasons.

Methods

Prospective epidemiological study reporting ACL injuries in professional male soccer players in the Qatar Stars League, with complete matches/training exposure over five seasons (2013–2014 to 2017–2018), corresponding to 2243 player seasons and 729 team months.

Results

37 complete ACL ruptures occurred in 37 players during 486 951  hours of player exposure. The overall ACL injury rate was 0.076 injuries/1000  hours of exposure (season range 0.045–0.098). Injury incidence during matches and training was 0.41 and 0.04 injuries/1000  hours of exposure, respectively. Match injury incidence was greater than that of training (OR 11.8, 95%  CI 6.21 to 23.23, p<0.001). Average injury-related time-loss following ACL injury was 225 days±65 (range 116–360). Overall injury burden was 16.3 days lost/1000  hours of exposure.

Conclusion

The overall ACL injury rate in professional male soccer players competing in the Middle East was 0.076 injuries/1000  hours of exposure, match injury incidence was greater than training, while the average ACL time-loss was 225 days.

The lack of standardized outcome measures following lower extremity injury in elite soccer: a systematic review

PURPOSE

Sport-specific, performance-based outcomes are increasingly used to improve evaluation of treatment efficacy in elite athletes; however, its usage in elite soccer may be limited. The purpose of this investigation is to (1) assess current outcome reporting in elite soccer; (2) identify any variability in reporting of outcomes; and (3) determine how sport-specific performance-based outcomes are utilized to assess treatment efficacy in elite soccer.

METHODS

A systematic review of the Pubmed, MEDLINE, and Embase, Scopus, SportDiscus, CINAHL and HealthSource: Nursing databases was performed without limitation on publication year. Inclusion criteria were (1) reporting of outcomes after a (2) lower extremity injury in (3) elite soccer players. The study's population, type of injury, return to play, as well as functional, objective, and sport-specific performance-based outcomes were extracted from each article. The methodological index for nonrandomized studies was used for quality assessment.

RESULTS

Twenty-one studies were selected after application of the inclusion and exclusion criteria. Objective outcomes were reported by 6 (29%) studies, and 6 (29%) employed patient-reported outcomes. The visual analog scale, Lysholm, and Tegner scores were the most common patient-reported outcomes (PROs). Return to play was reported by 18 (86%) studies, and only 2 (10%) utilized sport-specific performance-based outcomes. Despite the majority of studies reporting return to play, variation was seen in the definitions, and 15 (71%) studies reported the activity level of the players at final follow-up.

CONCLUSION

Assessment of treatment efficacy is limited in elite athletes, and PROs lack the sensitivity to identify residual performance deficits after an injury. Although performance-based measures are available at the elite level, these outcomes were seldom used for evaluation of treatment efficacy.

CLINICAL RELEVANCE

When treating elite soccer players, patient-reported outcome measures lack the sensitivity to detect changes in patient function, thus performance-based metrics may be more efficacious in assessing return from injury in these patients.

LEVEL OF EVIDENCE

IV.

Increased Postoperative Manual Knee Laxity at 2 Years Results in Inferior Long-term Subjective Outcome After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Increased postoperative rotatory knee laxity after anterior cruciate ligament (ACL) reconstruction may be associated with an increased risk of osteoarthritis and inferior subjective outcome, although long-term studies are lacking. In terms of anteroposterior knee laxity, this association has not yet been established. Purpose/Hypothesis: The purpose was to investigate whether postoperative knee laxity is associated with inferior long-term outcome in patients who have undergone ACL reconstruction. The hypothesis was that increased laxity would cause an inferior long-term clinical and radiographic outcome.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 193 patients underwent ACL reconstruction and were examined at both 2 and 16 years postoperatively. At the 2-year follow-up, knee laxity was tested by use of the Lachman test, the anterior drawer test, the pivot-shift test, and the KT-1000 arthrometer. Outcome variables examined at the 16-year follow-up involved a radiographic assessment of osteoarthritis, patient-reported outcome measurements, and the single-legged hop test.

RESULTS

At the long-term follow-up, 147 (76%) patients were examined. The mean follow-up period for the included patients was 16.4 ± 1.2 years. A negative Lachman test at 2 years resulted in a superior International Knee Documentation Committee (IKDC) score (76.3 ± 19.4 vs 67.8 ± 19.3, P < .05) and Lysholm score (85.2 ± 11.9 vs 76.9 ± 17.8, P < .05) at the 16-year follow-up. Correspondingly, a negative anterior drawer test at 2 years was associated with a superior IKDC score (75.3 ± 18.7 vs 62.9 ± 20.2, P < .05) and Lysholm score (84.1 ± 12.1 vs 72.6 ± 20.2, P < .05) at 16 years. A negative pivot-shift test resulted in a superior IKDC score (74.5 ± 18.8 vs 46.9 ± 17.8, P < .05), a superior Lysholm score (83.3 ± 13.4 vs 58.9 ± 23.0, P < .05), and an increased level of activity (Tegner activity scale, median [range]: 4 [1-10] vs 3 [0-5], P < .05). Osteoarthritis was overrepresented in patients with positive manual knee laxity tests, but the difference was not statistically significant. The KT-1000 arthrometer result was not correlated with any outcome variables assessed in this study.

CONCLUSION

Increased manual anteroposterior and rotatory knee laxity 2 years after ACL reconstruction is associated with an inferior long-term subjective outcome.

Knee osteoarthritis in professional football is related to severe knee injury and knee surgery

BACKGROUND

As a consequence of severe knee injuries, knee osteoarthritis (OA) seems prevalent in retired professional footballers. However, some epidemiological data remain missing, for instance whether knee OA is also prevalent in current professional footballers, whether knee OA is associated with knee injuries and surgeries, and whether knee OA leads to a lower level of functioning. Therefore, three research questions were answered: (i) what is the prevalence of knee osteoarthritis (OA) among current and retired professional footballers? (ii) is severe knee injury or knee surgery associated with knee OA among current and retired professional footballers? (iii) what are the consequences of knee OA on physical knee function among current and retired professional footballers?

METHODS

An observational study based on a cross-sectional design by means of questionnaires was conducted. Participants were current and retired professional footballers recruited by the World Players' Union (FIFPro). Information about severe knee injury and knee OA was gathered (medical record or team doctor), while physical knee function was assessed through a validated scale.

RESULTS

A total of 1360 participants (964 current and 396 retired professional footballers) were enrolled in the study (response rate of 54%). Prevalence of knee OA was 13% among current players and 28% among retired players (p < 0.01), being higher among older players. Current and retired professional footballers were nearly twice as likely to suffer from knee OA by every additional severe knee injury and by every additional knee surgery (risk ratio: 1.72-1.96; p < 0.01). Current and retired professional footballers with knee OA reported a lower level of physical knee function than current and retired players without OA (p < 0.01), their physical knee function being also lower than reference values (adult population, young athletic population and amateur footballers).

CONCLUSION

The prevalence of knee OA was higher among retired than among current professional footballers and reached up to 40%, leading to negative consequences for their physical knee function. Current and retired professional footballers were nearly twice as likely to suffer from knee OA by every additional severe knee injury and by every additional knee surgery incurred during their career. Management of knee OA should be prioritized among professional footballers, especially to prevent the worsening of the condition during their retirement years.

Anterior cruciate ligament repair - past, present and future

Background

This article provides a detailed narrative review on the history and current concepts surrounding ligamentous repair techniques in athletic patients. In particular, we will focus on the anterior cruciate ligament (ACL) as a case study in ligament injury and ligamentous repair techniques. PubMed (MEDLINE), EMBASE and Cochrane Library databases for papers relating to primary anterior cruciate ligament reconstruction were searched by all participating authors. All relevant historical papers were included for analysis. Additional searches of the same databases were made for papers relating to biological enhancement of ligament healing.

Current standard

The poor capacity of the ACL to heal is one of the main reasons why the current gold standard surgical treatment for an ACL injury in an athletic patient is ACL reconstruction with autograft from either the hamstrings or patella tendon. It is hypothesised that by preserving and repairing native tissues and negating the need for autograft that primary ACL repair may represent a key step change in the treatment of ACL injuries.

History of primary ACL repair

The history of primary ACL repair will be discussed and the circumstances that led to the near-abandonment of primary ACL repair techniques will be reviewed.

New primary repair techniques

There has been a recent resurgence in interest with regards to primary ACL repair. Improvements in imaging now allow for identification of tear location, with femoral-sided injuries, being more suitable for repair. We will discuss in details strategies for improving the mechanical and biological environment in order to allow primary healing to occur.

In particular, we will explain mechanical supplementation such as Internal Brace Ligament Augmentation and Dynamic Intraligamentary Stabilisation techniques. These are novel techniques that aim to protect the primary repair by providing a stabilising construct that connects the femur and the tibia, thus bridging the repair.

Bio enhanced repair

In addition, biological supplementation is being investigated as an adjunct and we will review the current literature with regards to bio-enhancement in the form platelet rich plasma, bio-scaffolds and stem cells. On the basis of current evidence, there appears to be a role for bio-enhancement, however, this is not yet translated into clinical practice.

Conclusions

Several promising avenues of further research now exist in the form of mechanical and biological augmentation techniques. Further work is clearly needed but there is renewed interest and focus for primary ACL repair that may yet prove the new frontier in ligament repair.

Posttraumatic Osteoarthritis Development and Progression in an Ovine Model of Partial Anterior Cruciate Ligament Transection and Effect of Repeated Intra-articular Methylprednisolone Acetate Injections on Early Disease

BACKGROUND

Partial anterior cruciate ligament (p-ACL) ruptures are a common injury of athletes. However, few preclinical models have investigated the natural history and treatment of p-ACL injuries.

PURPOSE

To (1) demonstrate whether a controlled p-ACL injury model (anteromedial band transection) develops progressive gross morphological and histological posttraumatic osteoarthritis (PTOA)-like changes at 20 and 40 weeks after the injury and (2) investigate the efficacy of repeated (0, 5, 10, and 15 weeks) intra-articular injections of methylprednisolone acetate (MPA; 80 mg/mL) in the mitigation of potential PTOA-like changes after p-ACL transection.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-one 3- to 5-year-old female Suffolk-cross sheep were allocated to 4 groups: (1) nonoperative controls (n = 5), (2) 20 weeks after p-ACL transection (n = 5), (3) 40 weeks after p-ACL transection (n = 6), and (4) 20 weeks after p-ACL transection + MPA (n = 5). Gross morphological grading and histological analyses were conducted. mRNA expression levels for inflammatory, degradative, and structural molecules were assessed.

RESULTS

p-ACL transection led to significantly more combined gross damage ( P = .008) and significant aggregate histological damage ( P = .009) at 40 weeks after p-ACL transection than the nonoperative controls, and damage was progressive over time. Macroscopically, MPA appeared to slightly mitigate gross damage at 20 weeks after p-ACL transection in some animals. However, microscopic analysis revealed that repeated MPA injections after p-ACL transection led to significant loss in proteoglycan content compared with the nonoperative controls and 20 weeks after p-ACL transection ( P = .008 and P = .008, respectively).

CONCLUSION

p-ACL transection led to significant gross and histological damage by 40 weeks, which was progressive over time. Multiple repeated MPA injections were not appropriate to mitigate injury-related damage in a p-ACL transection ovine model as significant proteoglycan loss was observed in MPA-treated knees.

CLINICAL RELEVANCE

A p-ACL injury leads to slow and progressive PTOA-like joint damage, and multiple repeated injections of glucocorticoids may be detrimental to the knee joint in the long term.

A review advocating caution with Major League Soccer expansion and investment in more rehabilitation professionals

BACKGROUND AND PURPOSE

Major League Soccer (MLS) has aggressively expanded from 10 teams to 23 teams. With the addition of more teams, the league will have to dictate a schedule that maximizes the league's popularity, while also maintaining the health of the players. A longer season and congested game schedule could increase the risk of injury for players. The purpose of this commentary is to make recommendations for the prevention of injuries among MLS players with respect to proposed league expansion.

DESCRIPTION OF TOPIC

MLS has lengthened the regular season with each expansion in teams. An increase in season length was seen in conjunction with the MLS expansion from 14 to 19 teams during the 2008 through 2013 seasons. Data from the inaugural MLS season found injury rates were higher in games compared to practices and more injuries occurred later in the season. With the expansion of MLS, anterior cruciate ligament tears appeared to have increased each year.

DISCUSSION

Current evidence suggests the implementation of a proper preseason in addition to the once-per-week game frequency would best promote player health and well-being. Players may benefit from in-season injury prevention training and weekly load monitoring.

Hip and groin time-loss injuries decreased slightly but injury burden remained constant in men's professional football: the 15-year prospective UEFA Elite Club Injury Study

BACKGROUND

Hip and groin injuries are common in men's professional football, but the time-trend of these injuries is not known.

AIM

To investigate hip and groin injury rates, especially time-trends, in men's professional football over 15 consecutive seasons.

STUDY DESIGN

Prospective cohort study.

SETTING

Men's professional football.

METHODS

47 European teams were followed prospectively for a varying number of seasons between 2001/2002 and 2015/2016, totalling 268 team seasons. Time-loss injuries and individual player exposure during training and matches were recorded. Injury rate was defined as the number of injuries/1000 hours and injury burden as the number of lay-off days/1000 hours. Time-trends for total hip and groin injuries and adductor-related injury rates were analysed using Poisson regression, and injury burden was analysed using a negative binomial regression model.

RESULTS

Hip and groin injuries contributed 1812 out of 12 736 injuries (14%), with adductor-related injury as the most common of hip and groin injuries (n=1139, 63%). The rates of hip and groin injury and adductor-related injury were 1.0/1000 hours and 0.6/1000 hours, and these rates decreased significantly with on average 2% (Exp(b)=0.98, 95% CI 0.97 to 0.99, P=0.003) and 3% (Exp(b)=0.97, 95% CI 0.95 to 0.99, P<0.001) per season (year on year), respectively. The seasonal trend of hip and groin injury burden did not improve (Exp(b)=0.99, 95% CI 0.97 to 1.01, P=0.40).

CONCLUSIONS

Hip and groin injuries constitute a considerable part of all time-loss injuries in men's professional football. Although there was a promising slight decreasing trend in the rates of hip and groin injury (as a category) and adductor-related injury (as a specific diagnosis), the injury burden remained at a consistent level over the study period.

Switching between pitch surfaces: practical applications and future perspectives for soccer training

INTRODUCTION

Soccer training and completion is conventionally practiced on natural grass (NG) or artificial turf (AT). Recently, AT pitches for training/competition, and of unstable surfaces for injury prevention training has increased. Therefore, soccer players are frequently exposed to variations in pitch surface during either training or competition. These ground changes may impact physical and physiological responses, adaptations as well as the injury. The aim of this review was to summarize the acute physical and physiological responses, chronic adaptations, and injury risk associated with exercising on different pitch surfaces in soccer.

EVIDENCE ACQUISITION

Eligible studies were published in English, had pitch surface as an independent variable, and had physical, physiological or epidemiological information as outcome variables. Specific data extracted from the articles included the training response, training adaptations or injury outcomes according to different pitch surfaces. A total of 224 studies were retrieved from a literature search.

EVIDENCE SYNTHESIS

Twenty articles met the inclusion criteria: 9 for acute physical and physiological responses, 2 for training adaptations and 9 for injury assessment. The literature lacks consistent evidence regarding the effects of pitch surface on performance and health outcomes in soccer players. However, it seems that occasionally switching training surfaces seems a valuable strategy for focusing on specific musculoskeletal queries and enhancing players' fitness. For instance, sand training may be occasionally proposed as complementary training strategy, given the recruitment of additional musculature probably not involved on firmer surfaces, but the possible training-induced adaptations of non-conventional soccer surfaces (e.g., sand) might potentially result into a negative transfer on AT or NG.

CONCLUSIONS

Since the specific physical demands of soccer can differ between surfaces, coaches should resort to the use of non-traditional surfaces with parsimony, emphasizing the specific surface-related motor tasks, normally observed on natural grass or artificial turf. Further studies are required to better understand the physiological effects induced by systematic surface-specific training, or switching between pitch surfaces.

Aerobic fitness in professional soccer players after anterior cruciate ligament reconstruction

Although anterior cruciate ligament (ACL) reconstruction is considered a successful procedure in restoring knee stability, few studies have addressed the issue of aerobic capacity after ACL surgery. Soccer players need technical, tactical and physical skills to succeed, such as good knee function and aerobic capacity. Our purpose is to evaluate aerobic fitness in ACL injured professional football players and six months after ACL reconstruction compared to a control group. Twenty athletes with ACL injury were evaluated and underwent ACL reconstruction with hamstrings autograft, and were compared to twenty healthy professional soccer players. The methods used to evaluate aerobic fitness were maximum oxygen uptake (VO_2max) and ventilatory thresholds with a treadmill protocol, before and six months after surgery, compared to a control group. Knee function questionnaires, isokinetic strength testing and body composition evaluation were also performed. Results: Median ACL-injured patients age was 21 years old, and controls 20.5 years old. (n.s.). Preoperative VO_2max in the ACL injured group was 45.2 ± 4.3 mL/kg/min, postoperative 48.9 ± 3.8 mL/kg/min and controls 56.9 ± 4.2 mL/kg/min. (p< .001 in all comparisons). Body composition evaluation was similar in all situations. Knee function questionnaires and quadriceps peak torque deficit improved after surgery but were significantly lower compared to controls. Conclusion: Aerobic fitness is significantly reduced in professional soccer players with ACL injury, and six months of rehabilitation was not enough to restore aerobic function after ACL reconstruction, compared to non-injured players of the same level.