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

Return to Play and Performance After Anterior Cruciate Ligament Reconstruction in Soccer Players: A Systematic Review of Recent Evidence

BACKGROUND

The available literature referring to the return to play (RTP) and performance after anterior cruciate ligament reconstruction (ACLR) has already been comprehensively summarized in team sports such as basketball or American Football. Therefore, in this sense, it is necessary to synthesize evidence relating to the mentioned parameters in soccer players who underwent ACLR.

OBJECTIVE

The aim of this systematic review was to examine RTP and the performance of soccer players after ACLR.

METHODS

Three electronic databases, Web of Science, Scopus, and PubMed, have been comprehensively searched to identify relevant articles. The following inclusion criteria were applied: (1) the sample of respondents consisted of soccer players irrespective of their age, sex, or level of competition; (2) athletes experienced anterior cruciate ligament injury and underwent ACLR; (3) outcomes estimated referred to the RTP, RTP at the preinjury level of competition, RTP time, performance, and career duration of soccer players; (4) studies were written in the English language. The methodological quality of the research was evaluated using the Methodological Index for Non-Randomized Studies (MINORS).

RESULTS

Databases searched yielded a total of 694 studies, of which 17 fulfilled the eligibility criteria and were included in the final analysis. These included 3657 soccer players, 2845 males and 812 females, who underwent ACLR and most commonly competed at the elite, national, amateur, and recreational levels. The results obtained indicated that 72% of soccer players successfully RTP and 53% RTP at the preinjury level of participation after ACLR. In addition, recent evidence provided in this literature review demonstrated that mean RTP time was 264 days or 8.7 months. Moreover, the majority of the studies unambiguously suggested that performance related to statistical aspects noticeably deteriorated compared with both the preinjury period and noninjured athletes. The mean career length of soccer players following ACL surgery was approximately between 4 and 5 years.

CONCLUSION

Although a high percentage of athletes RTP after a relatively short period of absence from the sports field compared with other sports closely related to soccer, ACLR negatively impacts soccer players' performance and career duration.

Anterior Cruciate Ligament Ruptures in Russian Premier League Soccer Players During the 2010 to 2021/2022 Competitive Seasons: The Epidemiology and Details of Return to Sports

Background

There are limited data on the epidemiology of anterior cruciate ligament (ACL) ruptures in elite adult soccer players, especially in the Russian Premier League (RPL). There is an increased risk of injury due to a combination of additional risk factors such as playing in extremely high and low temperatures, frequent long flights, and regular play on natural and artificial surfaces.

Purpose

To study the epidemiology of ACL ruptures and determine the patterns associated with their occurrence in RPL soccer players.

Study Design

Descriptive epidemiology study.

Methods

All ACL ruptures requiring surgery sustained by players competing in the RPL across 12 competitive seasons between 2010 and 2022 were analyzed. All required data were collected from media analysis and confirmed by club doctors.

Results

A total of 85 players sustained 100 injuries during 12 competitive seasons. A total of 96.5% of players returned to competitive play. The injury incidence in RPL and during participation of RPL teams in European Cups were 0.4760 and 0.5622 per 1000 playing hours, respectively. When analyzing the outcomes of the primary ACL surgery (a total of 76 operations), the following data were obtained: in 11 cases (14.5%), there was a reinjury on the ipsilateral knee joint and in 4 cases (5.3%) on the contralateral knee joint. The mean return-to-play time after all operations was 284 ± 116 days. The time of return to play after primary reconstruction was 289 ± 136 days, 278 ± 91 days after reconstruction on the contralateral knee and 271 ± 51.5 days after the first ACL revision reconstruction on the ipsilateral knee joints.

Conclusion

RPL ACL injury epidemiology is similar to that in the other leagues from around the world, although there are factors that can potentially influence the number of these injuries.

Italian research on anterior cruciate ligament: a bibliometric analysis

INTRODUCTION

This study analysed the trend of publications on anterior cruciate ligament (ACL) in Italy. It was hypothesised that publications on this topic have quickly increased in recent years due to increased knowledge of both clinical and radiological pathology.

METHODS

PubMed and Scopus were accessed on 29/11/2023. This retrieved 838 articles from PubMed and 1050 from Scopus. We analysed the top 10 authors, and journals in publication numbers, citation numbers, and citations per year. We have also looked at the top 10 institutions publishing on anterior cruciate ligament from Scopus as PubMed does not give this information in the output. Data mining was performed using the Orange software, Mac version 3.32.0 ( https://orangedatamining.com/ ) from the titles of all articles. A word cloud analysis of titles, authors, journals and universities was performed.

RESULTS

The peak of citations was in 2017 with 1529, whilst the peak of publications was in 2019 with 59 articles published. Analysing the number of publications and citations for the journal, the most impacted journal is Knee Surgery, Sports Traumatology, Arthroscopy with 5472 citations and 183 articles, followed by The American Journal of Sports Medicine, with 2722 citations and 56 articles and Arthroscopy with 1990 citations and 62 articles. Considering also international collaborations, the most cited author is Della Villa F. in 2020 with 43.67 citations per year. The Italian author with the major number of publications is Zaffagnini S. with 39 articles, whilst the author with the higher number of citations is Aglietti P. with 1612 citations.

CONCLUSIONS

ACL reconstruction has gained growing interest amongst the scientific community. Publications and citations presented a rising trend, the majority of the highly cited papers were contributed by few centres, and clinical trials were the most cited study designs. The long-term outcomes of ACL lesions have attracted interest. The authors hypothesised that shortly there will be an increase in articles analysing the results of ACL revisions, the use of lateral extra-articular tenodesis, and meniscus transplants.

LEVEL OF EVIDENCE IV

Cross-Sectional Study.

Patient Interest in Quadriceps Autograft Anterior Cruciate Ligament Reconstruction Is Increasing Over Other Autograft Options: A 12-Year Google Trends Analysis

Purpose

To use Google trends to explore differences in public interest among types of anterior cruciate ligament (ACL) autografts, specifically quadriceps tendon, patellar tendon, and hamstring tendon autografts, between 2008 and 2019.

Methods

Data were obtained by querying Google Trends for key terms and phrases for online search data ranging from January 2008 to December 2019. Relative search volumes were created based on searches related to ACL reconstruction with comparative analysis generated for search terms related to quadriceps ACL, patellar tendon ACL, and hamstring ACL autografts. Statistical analysis included linear regression analysis, comparison of quarterly search volume trends over time, and comparison of cumulative annual search volumes for 2008 versus 2019.

Results

Linear models for respective search terms were statistically significant for the quadriceps (P < .001) and patellar (P = .007) tendon autograft groups but not the hamstring group (P = .129). The quadriceps autograft group demonstrated a 12-year search volume trend change of 0.56, which was significantly greater than the hamstring (0.07; P < .001) and patellar tendon (0.168; P < .001) groups. There was no significant difference in the trend change between hamstring and patellar tendon groups (P = .20). Percent change in cumulative relative annual search volumes between 2008 and 2019 was 112% for the quadriceps tendon group, 12.9% for the hamstring group, and 18.6% for the patellar tendon group.

Conclusions

This study indicates a consistently increasing public interest in quadriceps tendon autograft for ACL reconstruction. The quadriceps autograft group demonstrated a significantly greater 12-year online search volume, greater linear correlation, and larger percent change between 2008 and 2019 compared with patellar tendon or hamstring autograft groups.

Clinical Relevance

Awareness of patient perceptions has value in informing shared decision-making, aligning patient expectations, and guiding areas of future research. Each of these has an impact on patient care. Being aware of patient interest and expectations is particularly important in areas with controversial or emerging research.

A comprehensive two-dimensional scoring system to assess the single-leg squat task in football players

BACKGROUND

The single-leg squat (SLS) is a safe and widespread functional test commonly performed in the mid-stages of rehabilitation after severe knee injuries. The use of reliable objective measures has been advocated to improve the quality of SLS assessment. The aim of this study was to describe a qualitative whole-body scoring system based on two-dimensional (2D) video analysis during SLS test and validate it against three-dimensional (3D) kinetics and kinematics.

METHODS

Thirty-four competitive football (soccer) players performed a series of SLS tasks. 3D kinematics and kinetics were collected through infrared cameras, and 2D video analysis was performed through a scoring system with sub-scores ranging from 0/2 (non-adequate movement) to 2/2 (adequate movement) based on frontal and lateral planes objective measurements. 3D kinematics and kinetics were grouped according to the results of the 2D evaluation and compared through the analysis of variance (P < 0.05).

RESULTS

Higher hip adduction, hip internalrotation, and knee valgus collapse were found in trials rated 0/2 or 1/2 compared with theone rated 2/2 in the limb stability score. Hip flexion and hip/knee moment ratio were lower in those scoring 0/2 comparedwith those scoring 2/2 in the movement strategy criterion. A low total score was associated with higherknee valgus collapse and lower hip/knee extensor moment ratio. Compensatory strategieswere found in frontal plane scores.

CONCLUSIONS

The 2D scoring system described was strongly associated with kinematics and kinetics from gold-standard 3D motion capture and might represent a valid tool to describe the movement quality of an SLS task.

Bone-patellar tendon-bone autograft is associated with a higher rate of return to preinjury levels of performance in high-level athletes than anterior cruciate ligament reconstruction using hamstring autograft

PURPOSE

Return to preinjury levels of performance (RTP) is the main goal after anterior cruciate ligament reconstruction (ACL-R) for athletes when ACL graft rupture is a career-threatening event. The purpose of this study was to elucidate the associated factors for RTP and subsequent ACL injury after ACL-R using bone-patellar tendon-bone (BPTB) or hamstring (HT) autograft in high-level athletes with a minimum postoperative follow-up of 24 months.

METHODS

This retrospective study included 157 patients who had preinjury Tegner activity level of 9 and underwent primary ACL-R using BPTB (average age, 16.9 years; 35 males and 36 females) or HT (average age, 17.2 years; 49 males and 37 females). The mean follow-ups were 33.6 months in BPTB and 44.5 months in HT, respectively. The data were obtained based on routine clinical follow-ups and telephone interviews performed by the surgeon. Multivariate logistic regression analysis was conducted to determine the association of patient variables with RTP and subsequent ACL injury.

RESULTS

Ninety-nine patients (63.1%) were able to RTP. The rate of RTP in BPTB (74.6%) was significantly higher than that of HT (53.5%) (p < 0.05). The overall average timing of RTP after ACL-R was 10.0 months while that was significantly earlier in BPTB (9.7 months) than in HT (10.5 months) (p < 0.05). Twenty-three (14.6%) and 21 patients (13.4%) had ACL graft ruptures and ACL injuries in the contralateral knees, respectively. Multivariate analyses showed that BPTB (odds ratio [OR], 2.590; 95% confidence interval [CI], 1.300-5.160; p = 0.007) was associated with a higher potential for RTP after ACL-R. The incidence of ACL graft rupture after ACL-R decreased with BPTB (OR, 0.861; 95% CI, 0.770-0.962; p = 0.009).

CONCLUSIONS

The use of BPTB autograft was associated with a higher rate of RTP and a lower incidence of ACL graft rupture compared to ACL-R using HT autograft.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Lever sign test for anterior cruciate ligament injuries: a diagnostic meta-analysis

BACKGROUND

Sports-related ACL (anterior cruciate ligament) injuries are frequent. Successful management requires early diagnosis and treatment. One of the clinical tests used to identify ACL damage is the lever sign test. This meta-analysis aimed to assess the lever sign test's diagnostic efficacy for ACL injuries.

METHODS

An extensive investigation of the Cochrane Library, Embase, and PubMed databases was conducted until April 2023. Studies assessing the lever sign test's diagnostic efficacy for ACL injuries were also included. A bivariate random-effects model was employed to acquire the pooled estimates of diagnostic odds ratios, specificity, positive and negative likelihood ratios, sensitivity, and curves of the summary receiver operating characteristic (SROC).

RESULTS

The meta-analysis comprised twelve investigations with a total of 1365 individuals. The lever sign test's combined sensitivity and specificity for the purpose of diagnosing injuries to the ACL were 0.810 (95% confidence interval [CI] 0.686-0.893) and 0.784 (95% CI 0.583-0.904), respectively. The positive and negative likelihood ratios were 3.148 (95% CI 1.784-5.553) and 0.210 (95% CI 0.084-0.528), respectively. The study revealed a diagnostic odds ratio of 17.656, with a 95% CI ranging from 4.800 to 64.951. The SROC curve's area was determined to be 0.912 (95% CI 0.857-0.967).

CONCLUSION

With high specificity and sensitivity, the lever sign test is a reliable diagnostic modality for ACL injuries. However, the test should be used in combination with other diagnostic tests to increase the accuracy of the diagnosis. Further investigations are warranted to assess the clinical practicability of the lever sign test in various populations and settings.

A comparison in knee flexor and extensor strength following ACL reconstruction in international, male soccer players receiving patellar tendon or hamstrings grafts

The aim of this study was to compare knee extensor and flexor strength recovery following anterior cruciate ligament (ACL) reconstruction between bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) grafts in international male soccer players undergoing comparable 6-month rehabilitation programmes. Seventeen players underwent ACL reconstruction with either an autogenous BPTB graft or HT graft. Knee extensor and flexor peak torques were measured at 3 months and 6 months in the injured and contralateral legs following surgery using isokinetic dynamometry. The moderate-large asymmetries in knee extensor peak torque between legs at 3 months across graft types (BPTB: p = 0.002, g = -0.94; HT: p = 0.02, g = -0.55) were reduced to trivial asymmetries at 6 months (BPTB: p = 0.30, g = -0.19; HT: p = 0.40, g = -0.16), with a non-significant difference in limb symmetry index (LSI) between grafts at 6 months (p = 0.62, g = -0.24). Similarly, moderate-large asymmetries in knee flexor peak torque between legs at 3 months across graft types (BPTB: p = 0.13, g = -0.50; HT: p = 0.01, g = -0.97) were reduced to trivial-small asymmetries at 6 months (BPTB: p = 0.25, g = 0.18; HT: p = 0.01, g = -0.47); however, a superior LSI was evident with BPTB compared to HT grafts at 6 months (p = 0.007, g = 1.43, large). Strength and conditioning professionals working with soccer players who are rehabilitating from ACL reconstruction after receiving a HT graft should give adequate attention to delivering suitable hamstring exercises that ensure optimal strength restoration.

Progress in research on and classification of surgical methods of arthroscopic reconstruction of the ACL and ALL using a shared tendon graft through the femoral tunnel

Anterior cruciate ligament (ACL) tear is a common clinical injury, and ACL reconstruction has reached a very mature stage. However, with the accumulation of cases, scholars have found that isolated ACL reconstruction may not completely solve the problem of knee rotational stability. With the increase in our understanding of knee joint structure, ACL combined with anterolateral ligament (ALL) reconstruction has become accepted by most scholars, and this operation has also achieved good clinical results. At present, there is no unified surgical method for ACL combined with ALL reconstruction. There are differences in bone tunnel location, reconstruction methods, and graft selection. Compared with the independent reconstruction of the ACL and ALL during the operation, shared tendon graft reconstruction of the ACL and ALL has the advantages of preserving tendon and avoiding tunnel convergence. So far, there is no relevant literature summarizing the reconstruction of the ACL and ALL with a shared tendon graft. This paper reviews the anatomic study of the ALL, the study of isometric points, surgical indications, and surgical methods and their classification for shared tendon graft reconstruction of the ACL and ALL.

Return-to-performance in elite soccer players after Achilles tendon ruptures: a study using a weighted plus/minus metric and matched-control analysis

PURPOSE

Studies have shown decreased match participation and shortened careers in athletes suffering Achilles tendon ruptures (ATRs), but assessment using a true performance metric is lacking. Plus/minus (PM) metrics provide a practical and objective approach to player performance assessment and are commonly used in other sports. This study aimed to quantify and compare individual player performance variations in elite football league players who sustained ATRs and returned to play within 1 year compared to those without ATRs, using a PM metric.

METHODS

Player and team data were sourced from Transfermarkt.com. Male players sustaining ATRs between 2007 and 2018 were identified through injury reports. A control group (CTRL) was matched by position, age, height, and league, with a 6:1 ratio of controls to ATR subjects. The day of injury was considered "time zero". Year -1 corresponds to the 360 days preceding injury, and Year 1 to the interval between 360 and 720 days after. Performance in the player's main team was evaluated using a previously validated weighted PM metric. Only data from Year -1 and Year 1 were used for ATR versus CTRL group comparisons. Statistical significance was set at p < 0.05.

RESULTS

The ATR group included 125 athletes. Data from more than 76,000 matches were analyzed. No statistically significant differences in net weighted PM metric between Year -1 and Year 1 were found.

CONCLUSION

No differences were found between athletes suffering from ATRs and controls regarding the weighted PM metric.

LEVEL OF EVIDENCE

III.

Field conditions is a risk factor for traumatic injury in youth football-A joint venture of medicine and hydrology

INTRODUCTION

The risk of traumatic injury in football has been suggested to be affected by field conditions. This study, therefore, aimed to investigate whether near surface water content of the football field, influenced the risk of traumatic injuries during a youth football tournament.

METHODS

At Dana Cup, an annual international youth football tournament in Denmark, all injuries were registered and classified at the on-site emergency department over 7 years. The incidence rate of traumatic injury was computed. Meteorological data and soil characteristics were used to simulate near surface water content of the playing fields. The incidence rate ratio (IRR) between water content and injury incidence rate was analyzed using a multivariate Poisson regression, controlling for tournament stage and demographical parameters.

RESULTS

About 2704 injuries were recorded corresponding to a risk time of 284 905 player hours. An inverse relation between water contents and the incidence rate of traumatic injury was found (IRR = 0.24 95% CI 0.1-0.7, p = 0.01). The incidence rate of traumatic injury increased with advancing tournament stage, that is, for the finals (IRR = 4.30 95% CI 2.8-6.6, p < 0.001). Also we found an interaction between dry fields and the final stage of tournament, further exacerbating this effect.

CONCLUSIONS

Our data suggest that the incidence rate of traumatic injury is increased with drier field conditions and advanced tournament stages.

Automated diagnosis of anterior cruciate ligament via a weighted multi-view network

Objective: To build a three-dimensional (3D) deep learning-based computer-aided diagnosis (CAD) system and investigate its applicability for automatic detection of anterior cruciate ligament (ACL) of the knee joint in magnetic resonance imaging (MRI). Methods: In this study, we develop a 3D weighted multi-view convolutional neural network by fusing different views of MRI to detect ACL. The network is evaluated on two MRI datasets, the in-house MRI-ACL dataset and the publicly available MRNet-v1.0 dataset. In the MRI-ACL dataset, the retrospective study collects 100 cases, and four views per patient are included. There are 50 ACL patients and 50 normal patients, respectively. The MRNet-v1.0 dataset contains 1,250 cases with three views, of which 208 are ACL patients, and the rest are normal or other abnormal patients. Results: The area under the receiver operating characteristic curve (AUC) of the ACL diagnosis system is 97.00% and 92.86% at the optimal threshold for the MRI-ACL dataset and the MRNet-v1.0 dataset, respectively, indicating a high overall diagnostic accuracy. In comparison, the best AUC of the single-view diagnosis methods are 96.00% (MRI-ACL dataset) and 91.78% (MRNet-v1.0 dataset), and our method improves by about 1.00% and 1.08%. Furthermore, our method also improves by about 1.00% (MRI-ACL dataset) and 0.28% (MRNet-v1.0 dataset) compared with the multi-view network (i.e., MRNet). Conclusion: The presented 3D weighted multi-view network achieves superior AUC in diagnosing ACL, not only in the in-house MRI-ACL dataset but also in the publicly available MRNet-v1.0 dataset, which demonstrates its clinical applicability for the automatic detection of ACL.

SARS-CoV-2 Infection Increases the Risk of Muscle Injury in Professional Male Soccer Players-A Retrospective Analysis of the Italian and Spanish Major Leagues

A retrospective cohort study on professional soccer players from the Serie A and LaLiga was conducted to investigate the correlation between SARS-CoV-2 infection and muscle injuries. Players were divided into two groups based on whether they contracted the SARS-CoV-2 infection (C+) or not (C-) during the 2020/2021 season. In the 2019-2020 season, both championships showed a similar number of muscular injuries (MI) between C+ and C- (Serie A: p = 0.194; 95% CI: -0.044 to 0.215, LaLiga p = 0.915; 95% CI: -0.123 to 0.137). In the 2020-2021 season, C+ had a significantly higher number of MI compared to C- in both championships (Serie A: p < 0.05; 95% CI 0.731 to 1.038; LaLiga: p < 0.05; 95% CI: 0.773 to 1.054). Multiple linear regression analysis confirmed that belonging to C+ in the season 2020/2021 was the variable that most strongly influenced the probability of having a muscle injury. Survival analysis revealed a hazard ratio of 3.73 (95% CI 3.018 to 4.628) and of 5.14 (95% CI 3.200 to 8.254) for Serie A and LaLiga respectively. We found an association between SARS-CoV-2 infection and increased risk of muscle injury, emphasizing the importance of carefully considering the infection in the decision-making process for returning to sport. Therefore, SARS-CoV-2 infection should be judged as a real injury requiring specific assessment and training programs.

Extracorporeal Shockwave Therapy Improves Outcome after Primary Anterior Cruciate Ligament Reconstruction with Hamstring Tendons

PURPOSE

The decision regarding the timepoint of a return to sports after anterior cruciate ligament (ACL) reconstruction is complex and depends on many factors, including objectively tested physical and psychological readiness as well as biological healing. The aim of this study was to investigate the influence of repetitive extracorporeal shockwave therapy (ESWT) on return-to-sports duration, clinical results and MRI results after ACL reconstruction with hamstring tendons (HT).

MATERIAL AND METHODS

In this prospective controlled study, all patients with acute ACL ruptures were treated by ACL reconstruction with HT. Patients were randomized into two groups (Group A: ESWT group; Group B: control group). Patients in the ESWT group received focused shockwave therapy 4, 5 and 6 weeks after ACL surgery. Follow-up investigations including IKDC score, Lysholm score, VAS and evaluation regarding return-to-sports timepoints that were conducted 3-, 6-, 9- and 12-months post-operation. An MRI investigation was performed 12-months post-operation and graft maturation (signal intensity ratio (SIR)) as well as femoral and tibial tunnel characteristics (bone marrow oedema, tunnel fluid effusion) were assessed.

RESULTS

In total, 65 patients (27.65 ± 7.07 years; 35 male/30 female) were included in this study. The mean timepoint for "return-to-pivoting-sports" was 27.92 weeks (±2.99) in the ESWT group as well as 42.64 weeks (±5.18) in the control group (p < 0.001). In the ESWT group 31 patients (vs.

CONTROL GROUP

n = 6) attained the "pre-injury activity level", whereas 6 patients (vs.

CONTROL GROUP

n = 22) did not reach this level within 12 months post-operation. The IKDC score, Lysholm score, and VAS showed significant improvement in the ESWT group compared with the control group for all time-points (p < 0.001). The mean SIR in the ESWT group revealed 1.81 (±0.88), whereas the control group showed a mean SIR of 2.68 (±1.04) (p < 0.01).

DISCUSSION

In conclusion, this is the first study investigating the effect of repetitive ESWT on ACL reconstruction with clinical outcome measurements, including the duration of return-to-sports activity and an MRI follow-up examination. Return-to-sports parameters, clinical scores and graft maturation were significantly improved in the ESWT group. This study may support an earlier return-to-sports timepoint by ESWT and is of high clinical relevance as ESWT is a cost-effective treatment option with no relevant side effects.

The Development of a Return to Performance Pathway Involving A Professional Soccer Player Returning From A Multi-Structural Knee Injury: A Case Report

This case report describes a male professional soccer player returning to match play (English Championship League) following a medial meniscectomy that occurred during the course of rehabilitation after Anterior Cruciate Ligament (ACL) reconstruction. The player underwent a medial meniscectomy eight months into an ACL rehabilitation program and following 10 weeks of rehabilitation successfully returned to competitive first team match play. This report outlines description of the pathology, the rehabilitation progressions, and the sports specific performance requirements of the player as they progressed through the return to performance pathway (RTP). The RTP pathway included nine distinct phases with evidenced based criteria required to exit each phase. The first five phases were indoor as the player progressed from the medial meniscectomy, through the rehabilitation pathways to the "gym exit Phase". The gym exit Phase was assessed with multiple criteria: a) capacity; b) strength; c) isokinetic dynamometry (IKD); d) hop test battery; e) force plate jumps; and f) supine isometric hamstring rate of force (RFD) development qualities to evaluate the players readiness to start sport specific rehabilitation. The last four phases of the RTP pathway are designed to regain the maximal physical capabilities (plyometric and explosive qualities) in the gym and included the retraining of on-field sport specific qualities utilizing the 'control-chaos continuum.' The player successfully returned to team play in the ninth and final phase of the RTP pathway. The purpose of this case report was to outline a RTP for a professional soccer player who successfully restored specific injury criteria (strength, capacity and movement quality), physical capabilities (plyometric and explosive qualities). and on-field sport specific criteria utilizing the 'control-chaos continuum.'

Level of Evidence

Level 4.

Effect of Quadriceps and Hamstring Strength Relative to Body Weight on Risk of a Second ACL Injury: A Cohort Study of 835 Patients Who Returned to Sport After ACL Reconstruction

Background

Anterior cruciate ligament (ACL) injuries are common sports-related injuries with a high risk of reinjury after return to sport (RTS). Rehabilitation aims to regain symmetrical knee strength and function to minimize the risk of a second ACL injury after RTS.

Purpose

To determine the effect of absolute quadriceps and hamstring strength, normalized by body weight, on the risk of a second ACL injury during the first 2 years after RTS in patients who have undergone ACL reconstruction (ACLR).

Study Design

Cohort study; Level of evidence, 3.

Methods

Data from patients after index ACLR at the time of RTS were extracted from a rehabilitation registry-Project ACL. Patients who had performed isokinetic tests for quadriceps and hamstring strength and hop tests before RTS were included. The endpoint was a second ACL injury or a follow-up of 2 years after RTS after ACLR.

Results

A total of 835 patients (46% women), with a mean age of 23.9 ± 7.7 years, were included. During the study period, 69 (8.3%) second ACL injuries (ipsilateral and contralateral) occurred. Greater relative quadriceps strength in the injured leg increased the risk of a second ACL injury (relative risk [RR], 1.69 [95% CI, 1.05-2.74]; P = .032). In patients who had recovered symmetrical quadriceps strength (limb symmetry index ≥90%), there was no effect of quadriceps strength on the risk of second ACL injury (RR, 1.33 [95% CI, 0.69-2.56]; P = .39). Quadriceps strength on the healthy side or hamstring strength, regardless of side, had no effect on the risk of a second ACL injury.

Conclusion

Greater relative quadriceps strength in the injured leg at the time of RTS after ACLR was associated with an increased risk of a second ACL injury. There was no effect of relative quadriceps strength on the risk of a second ACL injury in patients who had recovered symmetrical quadriceps strength.

Return to Play and Pattern of Injury After ACL Rupture in a Consecutive Series of Elite UEFA Soccer Players

Background

Anterior cruciate ligament rupture represents a career-threatening injury for professional soccer players.

Purpose

To analyze the pattern of injury, return to play (RTP), and performance of a consecutive series of elite professional soccer players after anterior cruciate ligament reconstruction (ACLR).

Study Design

Case series; Level of evidence, 4.

Methods

We evaluated the medical records of 40 consecutive elite soccer players who underwent ACLR by a single surgeon between September 2018 and May 2022. Patient age, height, weight, body mass index, position, injury history, affected side, RTP time, minutes played per season (MPS), and MPS as a percentage of playable minutes before and after ACLR were retrieved from medical records and from publicly available media-based platforms.

Results

Included were 27 male patients (mean ± SD age at surgery, 23.2 ± 4.3 years; range, 18-34 years). The injury occurred during matches in 24 players (88.9%), with a noncontact mechanism in 22 (91.7%). Meniscal pathology was found in 21 patients (77.8%). Lateral meniscectomy and meniscal repair were performed in 2 (7.4%) and 14 (51.9%) patients, respectively, and medial meniscectomy and meniscal repair were performed in 3 (11.1%) and 13 (48.1%) patients, respectively. A total of 17 players (63.0%) underwent ACLR with bone-patellar tendon-bone autograft and 10 (37.0%) with soft tissue quadriceps tendon. Lateral extra-articular tenodesis was added in 5 patients (18.5%). The overall RTP rate was 92.6% (25 of 27). Two athletes moved to a lower league after surgery. The mean MPS% during the last preinjury season was 56.69% ± 21.71%; this decreased significantly to 29.18% ± 20.6% (P < .001) in the first postoperative season and then increased to 57.76% ± 22.89% and 55.89% ± 25.8% in the second and third postoperative seasons. Two (7.4%) reruptures and 2 (7.4%) failed meniscal repairs were reported.

Conclusion

ACLR in elite UEFA soccer players was associated with a 92.6% rate of RTP and 7.4% rate of reinjury within 6 months after primary surgery. Moreover, 7.4% of soccer players moved to a lower league during the first season after surgery. Age, graft selection, concomitant treatments, and lateral extra-articular tenodesis were not significantly associated with prolonged RTP.

The incidence of anterior cruciate ligament injury in youth and male soccer athletes: an evaluation of 17,108 players over two consecutive seasons with an age-based sub-analysis

PURPOSE

To evaluate the incidence of anterior cruciate ligament (ACL) injuries in male athletes from professional soccer clubs over two consecutive seasons (2018-2019) with a sub-analysis based on age category: under-13 (U-13), under-15 (U-15), under-17 (U-17), and under-20 (U-20) years.

METHODS

A total of 17,108 young male soccer players were retrospectively reviewed from sixty-three professional clubs in the four highest Brazilian soccer divisions. Data regarding the number of athletes and the number of ACL injuries confirmed by magnetic resonance imaging (MRI) exams in the 2018 and 2019 seasons were collected. Incidence of ACL injury were compared by season, age category (under-13; under-15; under 17; and under-20), demographic region, and club division.

RESULTS

Clubs from all regions of Brazil participated in the study. A total of 336 primary ACL injuries were diagnosed over the two seasons (8,167 athletes during the 2018 season and 8,941 athletes during the 2019 season) among all athletes, which corresponds to 2% of the included athletes. There were 11 cases (0.3%) in the under-13, 53 cases (1.3%) in the under-15, 107 cases (2.5%) in the under-17, and 165 cases (3.8%) in the under-20 age category. There was a higher incidence of ACL injury in the older age groups (p < 0.001).

CONCLUSION

A total of 336 ACL injuries were identified in 17,108 youth soccer players from 63 professional clubs with an overall incidence of 2% over 2 seasons of competition. ACL injury rate ranged from 0.3% to 3.8% and was higher in the older and more competitive club divisions.

LEVEL OF EVIDENCE

IV.

Anterior cruciate ligament ruptures in Spanish soccer first division: An epidemiological retrospective study

BACKGROUND

Anterior cruciate ligament (ACL) injury is a severe and complex sport-related injury that can threaten an individual's sporting career. The purpose of this study is to investigate the epidemiological patterns of ACL ruptures in Spanish male first-division soccer players.

METHODS

The Transfermarkt and Besoccer online electronic databases were screened for ACL injuries between 2010-2011 and 2019-2020 seasons. Injury incidence, injury mechanism, side of the injury, recurrence of the injury, days of recovery and severity, player's position, dominance, season, and moment in which the injury occurs were collected.

RESULTS

A total of 110 ACL ruptures were registered, with 15.45% of them being re-ruptures either ipsilateral (6.36%) or contralateral ruptures (9.09 %). The ACL incidence rate was 0.0364 per 1000 h of total play with a 68-fold risk in matches compared with training. Predominant injury mechanism was non-contact (56.36%) and the mean lay-off time was 218.8 days, with higher incidence in September-October and March-April. Goalkeeper was found to be the less affected position.

CONCLUSIONS

This investigation identified an average of 11 ACL tears per season in the Spanish first-division soccer league, most of them occurring in matches with approximately one ACL injury per team every two seasons. Our results from media-based platforms are in accordance with reports based on data from healthcare databases. Further research is needed to corroborate these findings in equivalent contexts. Descriptive studies are classified as Level III evidence according to Daly et al., 2007.

The relative age effect is widespread among European adult professional soccer players but does not affect their market value

BACKGROUND

The relative age effect (RAE) is most prevalent in highly competitive youth soccer and persists to a lesser extent in senior soccer. However, it is known that soccer players born in the second half of the year are as successful at senior level, indicating that they are equally talented although under-represented at youth level due to bias during the selection process, in which the emphasis is on more pronounced physical qualities in a specific period of time. Examining the prevalence of the RAE among professional soccer players depending on the level of competition and playing position, as well as analyzing the relationship between the player's birth quarter and market value, are of scientific interest.

METHODS

The dates of birth, playing position, and market value of all adult male soccer players included in the final rosters of teams from the top-division of 54 European countries, listed on www.transfermarkt.com on August 15th, 2020, were analyzed (18,429 soccer players in total). All players were categorized into four groups according to the quarter of birth (Q) and playing position. All teams were further sub-divided in groups depending on the soccer clubs' level of representation in the UEFA Champions League.

RESULTS

Of 18,429 players, 30.9% were born in Q1, 25.7% in Q2, 23.8% in Q3 and 19.6% in Q4. The number of soccer players born in Q1 was lower in less competitive leagues. The number of players born in Q1 decreased as the level of competition decreased; the highest percentage of these players was observed in clubs that are among the top 50 ranked in UEFA or compete in the most prestigious European championships. The RAE was less pronounced in teams that participate in lower competitive championships. There was no significant difference in market value between players playing position and level of competition when born in different quarters. Although, the most expensive soccer players in the European championships were late-born forwards. Players of various groups differed in their market value.

CONCLUSIONS

The RAE is currently prevalent in all the most competitive senior soccer leagues and teams in Europe regardless of playing position. There are no significant differences in market value between players of the same playing position and level of competition when born in different quarters. The most expensive soccer players in the European championships are forwards born in Q4. These findings may indicate that the under-representation of "late-born" soccer players in youth, and then consequently in adult soccer, is not associated with lower talent, but with other factors, possibly based on physiological characteristics and socio-cultural factors. Further measures are needed to mitigate the discriminatory effects of selection bias based on the RAE.

High revision arthroscopy rate after ACL reconstruction in men's professional team sports

PURPOSE

The study analysed unique data on anterior cruciate ligament (ACL) injuries among German professional male team sports over five consecutive seasons with the aim of improving medical outcomes in the future. Sport-specific differences in injury occurrence, concomitant injuries, timing of ACL reconstruction, graft type selection and short-term complications were examined.

METHODS

This retrospective study analysed trauma insurance data on all complete ACL tears from players with at least one competitive match appearance in the two highest divisions of German male basketball, ice hockey, football and handball. Each complete ACL tear registered by clubs or physicians between the 2014/15 and 2018/19 seasons with the German statutory accidental insurance for professional athletes (VBG) as part of occupational accident reporting was included.

RESULTS

In total, 189 out of 7517 players (2.5%) sustained an ACL injury, mainly in handball (n = 82; 43.4%) and football (n = 72; 38.1%) followed by ice hockey (n = 20; 10.6%) and basketball (n = 15; 7.9%).Seventeen players (9.0%) also sustained a second ACL injury. Thus, 206 ACL injuries were included in the analysis. The overall match incidence of ACL injuries was 0.5 per 1000 h and was highest in handballs (1.1 injuries per 1000 h). A total of 70.4% of ACL injuries involved concomitant injury to other knee structures, and 29.6% were isolated ACL injuries. The highest rate of isolated ACL injuries was seen in ice hockey (42.9%). All ACL injuries, except for one career-ending injury, required surgery. In the four analysed team sports, hamstring tendons (71.4%) were the most commonly used grafts for ACL reconstruction; football had the highest percentage of alternative grafts (48.7%). During rehabilitation, 22.9% of all surgically treated ACL injuries (n = 205) required at least two surgical interventions, and 15.6% required revision arthroscopy. The main cause of revision arthroscopy (n = 32; 50.0%) was range-of-motion deficit due to arthrofibrosis or cyclops formation.

CONCLUSION

The present study shows an overall high rate of revision arthroscopy after ACLR (15.6%), which should encourage surgeons and therapists to evaluate their treatment and rehabilitation strategies in this specific subpopulation. Hamstring tendon grafts are most commonly used for ACL reconstruction but have the highest revision and infection rates. Handball shows the highest ACL injury risk of the four evaluated professional team sports. Concomitant injuries occur in the majority of cases, with the highest share of isolated ACL injuries occurring in ice hockey.

LEVEL OF EVIDENCE

Level III.

Rates and Levels of Elite Sport Participation at 5 Years After Revision ACL Reconstruction

BACKGROUND

There is a paucity of data regarding return to play (RTP), level of competition, and longevity of play after revision of anterior cruciate ligament (ACL) reconstruction (ACLR) in elite athletes.

PURPOSE

To report RTP rates and competition levels in elite athletes at the point of RTP, as well as at 2 and 5 years after revision ACLR, and the effect of meniscal and chondral pathology at revision surgery on these outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective review of a consecutive series of all revision ACLRs undertaken by the senior author between 2009 and 2019, with a minimum 2-year follow-up, was carried out. Outcome measures were RTP rates and competition level.

RESULTS

A total of 49 knees in 48 elite athletes met the inclusion criteria. After revision ACLR, 43 (87.8%) elite athletes achieved RTP, of whom 75.5% were at the same level. At 2 years after surgery, 39 (79.6%) were still playing, 25 (51%) at the same level; at 5 years after surgery, 20 (44.4%) were still playing, 9 (20%) at the same level. Elite athletes with <50% thickness or no articular cartilage lesions were more likely to RTP (94.6% vs 66.7%; P = .026), as well as return to the same competition level (83.8% vs 50%; P = .047), compared with those with ≥50% thickness chondral lesions. Those without medial meniscal pathology were more likely to RTP at the same level after revision surgery (94.4% vs 64.5%; P = .036). The median time elite athletes continued to play after revision ACLR was 73 months (95% CI, 43.4-102.6); 23 months at the same level (95% CI, 13.6-32.4). The probability of still playing at 5 years after surgery was 55.9%, with a 22.5% chance of maintaining preinjury competition level.

CONCLUSION

In elite athletes, RTP rates and competition level decreased over time after revision ACLR. The presence of >50% thickness chondral pathology was associated with lower RTP rates and competition level at RTP time, while medial meniscal pathology was associated with lower competition level at RTP.

High return to sport rate and few re-ruptures at long term in professional footballers after anterior cruciate ligament reconstruction with hamstrings

PURPOSE

Anterior cruciate ligament (ACL) ruptures are considered high burden injuries in sports with high pivotal activity, especially for professional footballers. A lack of evidence exists about long-term follow up of professional elite athletes who underwent ACL reconstruction. The purpose of the study is to analyze the return to play and the career of professional footballers who underwent ACL reconstruction with hamstrings, to evaluate re-rupture and reoperation at either indexed and contralateral knee, and to assess the long-term clinical subjective outcomes and satisfaction.

METHODS

Twenty-eight professional footballers that underwent 33 ACL reconstructions were retrospectively included in the study. All surgical interventions were performed using hamstring tendons graft and an over the top technique. Inclusion criteria were: inability to compete due to joint instability caused by total or subtotal ACL lesion, patients contracted to a professional football team at time of surgery. Exclusion criteria were: multi-ligament reconstruction or concomitant meniscal allograft transplantation. Patients were contacted by phone and a brief questionnaire about surgery was administered. Subsequently, a Lysholm knee scoring scale was obtained. After that, an online research was performed on publicly available websites in order to retrieve information of the patients included after surgery.

RESULTS

In all cases, ACL Reconstruction was performed with hamstring tendons using a non-anatomic Double-Bundle technique in 16 cases (49%), an Over-The-Top Single-Bundle technique in 9 cases (27%), and an Over-The-Top Single-Bundle plus Lateral Plasty technique in 8 cases (24%); moreover, a meniscal lesion was present in 20 cases (61%). Three (9%) of the 33 ACL reconstruction failed (2/16 Double-Bundle, 1/9 Single- Bundle, 0/8 Single-Bundle + Lateral Plasty; p = n.s.), with two of them within 12 months from surgery. Other procedures, mainly arthroscopic meniscectomies, were performed in 10 cases (30%). The first official match was played after an average of 8.0 ± 3.6 (4.6-18.2) months in 31 cases (94%). Patients were evaluated after 12.6 ± 3.3 years (6.7-17.5) from the indexed ACL reconstruction. The average Lysholm score was 94.2 ± 8.3.

CONCLUSIONS

In our small case-series, professional soccer players were able to return to play at a competitive level with a hamstrings over the top technique. Patients with long careers had a high percentage of reoperation on the contralateral knee.

LEVEL OF EVIDENCE

IV.

Risk Factors for Anterior Cruciate Ligament Graft Failure in Professional Athletes: An Analysis of 342 Patients With a Mean Follow-up of 100 Months From the SANTI Study Group

BACKGROUND

Anterior cruciate ligament (ACL) injuries are among the most common knee injuries sustained in elite sport, and athletes generally undergo ACL reconstruction (ACLR) to facilitate their return to sport. ACL graft rupture is a career-threatening event for elite athletes.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine the risk factors for graft failure in professional athletes undergoing ACLR. It was hypothesized that athletes who underwent combined ACLR with a lateral extra-articular procedure (LEAP) would experience significantly lower rates of graft rupture in comparison with those who underwent isolated ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Professional athletes who underwent primary ACLR with a minimum follow-up of 2 years were identified from the Santy database. Patients were excluded if they underwent major concomitant procedures, including multiligament reconstruction surgery or osteotomy. Further ipsilateral knee injury, contralateral knee injury, and any other reoperations or complications after the index procedure were identified by interrogation of the database and review of the medical notes.

RESULTS

A total of 342 athletes with a mean follow-up of 100.2 ± 51.9 months (range, 24-215 months) were analyzed. Graft failures totaling 31 (9.1%) were reported, requiring revision surgery because of symptomatic instability. The rate of graft failure was significantly higher when ACLR was not combined with a LEAP (15.5% vs 6.0%; P = .0105) and in athletes aged 21 years or younger (13.8% vs 6.6%; P = .0290). A multivariate analysis was performed using the Cox model and demonstrated that athletes undergoing an isolated ACLR were at >2-fold risk of ACL graft rupture (hazard ratio [HR], 2.678 [1.173; 4.837], P = .0164) when compared with those undergoing a combined ACLR with a LEAP. Additionally, athletes aged ≤21 years were also at >2-fold risk of graft failure (HR, 2.381 [1.313; 5.463]; P = .0068) than those aged >21 years. Sex, sport, and graft type were not found to be significant risk factors for graft failure.

CONCLUSION

Professional athletes undergoing isolated ACLR and aged ≤21 years are at >2-fold greater risk of graft failure. Orthopaedic surgeons treating elite athletes should combine an ACLR with a LEAP to improve ACL graft survivorship.

The Effects of a Combined Pre- and Post-Operative Anterior Cruciate Ligament Reconstruction Rehabilitation Program on Lower Extremity Muscle Imbalance

This study examined whether the 5-week pre-operative progressive exercise rehabilitation program with weekly monitoring contributed to a significantly lower muscle activity imbalance in the treatment group, both before and immediately after anterior cruciate ligament reconstruction (ACLR), as well as during the next 5 weeks in comparison to the control group. Twelve professional soccer players took part in the study (from among the top three Polish levels of competition) (age: 26 ± 5 years, body mass: 73 ± 7 kg, stature: 180 ± 6 cm, training experience: 15 ± 4 years). The participants were randomly assigned to the treatment group (n = 6) or to the control group (n = 6). Both groups performed the same pre- and post-operative progressive exercise rehabilitation program, while the rehabilitation of the treatment group was extended by supplementary body-weight functional stabilization training. The three-way repeated-measures ANOVA revealed a statistically significant interaction for muscle × group × time (p < 0.0001; F = 24.897; η2 = 0.806). The post-hoc analysis for the interaction effect of muscle × group × time indicated a significantly higher muscle activity imbalance for every measured muscle in the control group at any time point than in the treatment group (from p = 0.036 to p < 0.0001). The muscle activity imbalance was significantly higher from the 1st to 4th weeks than in the last week before surgery for quadriceps (p < 0.016 for all) and hamstrings (p < 0.001). However, in the case of gluteal muscles’ activity imbalance, it was significantly higher at every time point of the post-operative phase than in the last week before surgery (p < 0.001). The results of this study showed that the 5-week pre-operative rehabilitation program with weekly monitoring influenced outcomes of the post-operative phase. Nevertheless, performing both pre- and post-ACLR rehabilitation significantly reduced the muscle activity imbalance of lower limbs, but in the case of the quadriceps muscles, not to a sufficient level.

Factors affecting return to play and graft re-rupture after primary ACL reconstruction in professional footballers

PURPOSE

Modern ACL reconstruction (ACL-R) techniques have led to improved outcomes in professional footballers. The aim of this study was to identify and assess patient, surgical and post-operative factors that affected rates and time to return to play (RTP) as well as ACL re-rupture rates.

METHODS

A retrospective review of consecutive ACL-R undertaken in professional footballers between 2005 and 2018.

RESULTS

Two-hundred and thirty-two knees in 215 professional footballers (17 bilateral) were included. 205 (88.9%) were male and average age at surgery was 23.3 ± 4.4 years. Two-hundred and twenty-two (96.1%) returned to professional football, with 209 (90.1%) returning to the same or higher Tegner level. Subgroup analysis revealed three factors that independently affected RTP rate: (1) Players under 25 years had a higher rate of RTP (99.3% vs 90.2%. p = 0.001); (2) a subsequent operation prior to RTP decreased RTP rate from 98.2 to 89.7% (p = 0.009).; (3) undergoing meniscal surgery at ACL-R decreased RTP rate (p = 0.002). The mean time to RTP from surgery was 10.5 ± 3.6 months. Factors found to increase RTP time included age under 25 (11.0 vs 9.7 months, p = 0.005), recurrent effusions (11.4 vs 10.2 months, p = 0.035), and medial meniscal repair at ACL-R compared to meniscectomy (12.5 vs 9.6 months, p = 0.022). The surgical technique varied over the study period in relation to graft type, femoral tunnel position and addition of lateral extra-articular tenodesis (LET). Overall, the re-rupture rate was 8.2% at 2 years. Patella tendon autograft in an anteromedial bundle femoral tunnel position with addition of LET has the lowest re-rupture rate (2.0%).

CONCLUSION

Primary ACL-R in professional footballers yields high rates of RTP (96.1%), with 90.1% at the same level or higher, at a mean 10.5 months. Patients under 25 years not only had a significantly higher RTP rate, but also had a lengthier period of rehabilitation.

LEVEL OF EVIDENCE

Level IV.

Gene Therapy in Orthopaedics: Progress and Challenges in Pre-Clinical Development and Translation

In orthopaedics, gene-based treatment approaches are being investigated for an array of common -yet medically challenging- pathologic conditions of the skeletal connective tissues and structures (bone, cartilage, ligament, tendon, joints, intervertebral discs etc.). As the skeletal system protects the vital organs and provides weight-bearing structural support, the various tissues are principally composed of dense extracellular matrix (ECM), often with minimal cellularity and vasculature. Due to their functional roles, composition, and distribution throughout the body the skeletal tissues are prone to traumatic injury, and/or structural failure from chronic inflammation and matrix degradation. Due to a mixture of environment and endogenous factors repair processes are often slow and fail to restore the native quality of the ECM and its function. In other cases, large-scale lesions from severe trauma or tumor surgery, exceed the body’s healing and regenerative capacity. Although a wide range of exogenous gene products (proteins and RNAs) have the potential to enhance tissue repair/regeneration and inhibit degenerative disease their clinical use is hindered by the absence of practical methods for safe, effective delivery. Cumulatively, a large body of evidence demonstrates the capacity to transfer coding sequences for biologic agents to cells in the skeletal tissues to achieve prolonged delivery at functional levels to augment local repair or inhibit pathologic processes. With an eye toward clinical translation, we discuss the research progress in the primary injury and disease targets in orthopaedic gene therapy. Technical considerations important to the exploration and pre-clinical development are presented, with an emphasis on vector technologies and delivery strategies whose capacity to generate and sustain functional transgene expression in vivo is well-established.

Association between outdoor temperature and achilles tendon repair: A 14-years nationwide population-based cohort study

The incidence of achilles tendon rupture varies by gender, age, and seasonal variation. However, there has been no study as yet linking achilles tendon rupture to daily fluctuations in outdoor temperature. The purpose of this study was to investigate the association between outdoor temperature and achilles tendon rupture using a Korea Meteorological Administration database and a Korean National Health Insurance Service-National Sample Cohort database. Between 2002 and 2015, all instances of achilles tendon repair were retrieved from the National Health Insurance Service-National Sample Cohort database to examine sociodemographic factors, specifically sex, age, residential area, and income level. Minimum age requirement was 20 years. Outdoor temperatures recorded at 16 observation points in South Korea were also acquired from the Korea Meteorological Administration data center for analysis. Overall, 850 (0.119%) of 713,456 individuals in the National Health Insurance Service-National Sample Cohort database underwent achilles tendon repair between 2002 and 2015. Yearly procedural totals increased with advancing age, peaking at ages 30–39 years (14.6 per 100,000 persons) and declining thereafter. Minimum, median, and maximum outdoor temperatures were associated with achilles tendon repair (p<0.05), as did household income. In multivariate logistic regression analysis, outdoor temperatures, sex, age, and household income emerged as factors significantly associated with achilles tendon repair. Outcomes of this study confirm an association between incidence of achilles tendon repair and outdoor temperature, the latter denoting a novel index and likely surrogate measure of vigorous physical activity afforded by warmer weather.

Epidemiology of Achilles Tendon Rupture in Italian First Division Football (Soccer) Players and Their Performance After Return to Play

OBJECTIVE

To evaluate the epidemiology, incidence rate, incidence proportion, and prevalence of Achilles tendon ruptures (ATRs) in professional footballers and their performance after the injury.

DATA SOURCES

Professional male footballers participating in Serie A in 11 consecutive seasons (2008/2009-2018/2019) were screened to identify ATRs through the online football archive transfermarkt.com. Exposure in matches and training was calculated. The number of matches played in the 5 seasons before and after ATRs was obtained, when possible, together with transfers to a different team or participation in lower Divisions.

MAIN RESULTS

Eleven ATRs were found in 11 footballers with a mean age of 29.8 ± 4.4 years; 72% of ATR involved the nondominant leg; 58% occurred during matches and 42% during training, with no peculiar distribution along the playing season. The overall incidence proportion was 0.17% (0.11% during matches and 0.06% during training). The overall incidence rate was 0.007 injuries per 1000 hours of play (0.051 during matches and 0.003during training; P < 0.0001). All players returned to play soccer after a mean of 170 ± 35 days after ATRs and participated in an official match after a mean of 274 ± 98 days. However, 2 seasons after ATRs, 3 footballers were playing in a lower Division; 1 played less than 10 matches (compared with >25 matches in the 5 seasons before an ATR) and 1 had retired.

CONCLUSIONS

An overall ATR rate of 0.007 per 1000 hours of soccer play and an incidence proportion of 0.17% were reported. All footballers return to play; however, up to 40% players decreased the level of play by reducing the number of games or participating in a lower Division 2 seasons after an ATR.

Pre-injury performance is most important for predicting the level of match participation after Achilles tendon ruptures in elite soccer players: a study using a machine learning classifier

PURPOSE

Achilles tendon ruptures (ATR) are career-threatening injuries in elite soccer players due to the decreased sports performance they commonly inflict. This study presents an exploratory data analysis of match participation before and after ATRs and an evaluation of the performance of a machine learning (ML) model based on pre-injury features to predict whether a player will return to a previous level of match participation.

METHODS

The website transfermarkt.com was mined, between January and March of 2021, for relevant entries regarding soccer players who suffered an ATR while playing in first or second leagues. The difference between average minutes played per match (MPM) 1 year before injury and between 1 and 2 years after the injury was used to identify patterns in match participation after injury. Clustering analysis was performed using k-means clustering. Predictions of post-injury match participation were made using the XGBoost classification algorithm. The performance of this model was evaluated using the area under the receiver operating characteristic curve (AUROC) and Brier score loss (BSL).

RESULTS

Two hundred and nine players were included in the study. Data from 32,853 matches was analysed. Exploratory data analysis revealed that forwards, midfielders and defenders increased match participation during the first year after injury, with goalkeepers still improving at 2 years. Players were grouped into four clusters regarding the difference between MPMs 1 year before injury and between 1 and 2 years after the injury. These groups ranged between a severe decrease (n = 34; - 59 ± 13 MPM), moderate decrease (n = 75; - 25 ± 8 MPM), maintenance (n = 70; 0 ± 8 MPM), or increase (n = 30; 32 ± 13 MPM). Regarding the predictive model, the average AUROC after cross-validation was 0.81 ± 0.10, and the BSL was 0.12, with the most important features relating to pre-injury match participation.

CONCLUSION

Most players take 1 year to reach peak match participation after an ATR. Good performance was attained using a ML classifier to predict the level of match participation following an ATR, with features related to pre-injury match participation displaying the highest importance.

LEVEL OF EVIDENCE

I.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

IV.

Reliability and Repeatability of ACL Quick Check®: A Methodology for on Field Lower Limb Joint Kinematics and Kinetics Assessment in Sport Applications

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

Exercise-Based Training Strategies to Reduce the Incidence or Mitigate the Risk Factors of Anterior Cruciate Ligament Injury in Adult Football (Soccer) Players: A Systematic Review

Anterior cruciate ligament (ACL) is one of the most concerning injuries for football players. The aim of this review is to investigate the effects of exercise-based interventions targeting at reducing ACL injury rate or mitigating risk factors of ACL injury in adult football players. Following PRISMA guidelines, a systematic search was conducted in CINAHL, Cochrane Library, PubMed, Scopus, SPORTDiscus and Web of Science. Studies assessing the effect of exercise-based interventions in ACL injury incidence or modifiable risk factors in adult football players were included. 29 studies evaluating 4502 male and 1589 female players were included (15 RCT, 8 NRCT, 6 single-arm): 14 included warm-up, 7 resistance training, 4 mixed training, 3 balance, 1 core stability and 1 technique modification interventions. 6 out of 29 studies investigated the effect of interventions on ACL injury incidence, while the remaining 23 investigated their effect on risk factors. Only 21% and 13% studies evaluating risk of injury variables reported reliability measures and/or smallest worthwhile change data. Warm-up, core stability, balance and technique modification appear effective and feasible interventions to be included in football teams. However, the use of more ecologically valid tests and individually tailored interventions targeting specific ACL injury mechanisms are required.

Analysis of more than 20,000 injuries in European professional football by using a citizen science-based approach: An opportunity for epidemiological research?

OBJECTIVES

It has been claimed that analyses of large datasets from publicly accessible, open-collaborated ("citizen science-based") online databases may provide additional insight into the epidemiology of injuries in professional football. However, this approach comes with major limitations, raising critical questions about the current trend of utilizing citizen science-based data. Therefore, we aimed to determine if citizen science-based health data from a popular online database on professional football players can be used for epidemiological research, i.e. in providing results comparable to other data sources used in previously published studies.

DESIGN

Retrospective database analysis.

METHODS

Transfermarkt.com (Transfermarkt; Hamburg; Germany) is a publicly accessible online database on various data of professional football players. All information provided in the section "injury history" of football players from the top five European leagues over a period of ten seasons (2009/10-2018/19) was analyzed. Frequency, characteristics, and incidence of injuries were reported according to seasons and countries, and results compared with three previously published databases (a scientific injury surveillance, a media-based study, and an insurance database).

RESULTS

Overall, 21,598 injuries of 11,507 players were analyzed from the Transfermarkt.com database. Incidence was 0.63 injuries per player-season (95% confidence interval 0.62 to 0.64) but significant differences between subgroups (countries, years) were found. In comparison to other databases, citizen science-based data was associated with lower injury incidences and higher proportions of severe injuries.

CONCLUSIONS

With few exceptions (e.g., severe injuries), the use of citizen science-based health data on professional football players cannot be recommended at present for epidemiological research.

Impact of COVID-19 lockdown on the epidemiology of soccer muscle injuries in Italian Serie A professional football players

OBJECTIVE

To evaluate the influence that COVID-19 lockdown had on the epidemiology of soccer musculoskeletal injuries during 2019/2020 Italian First Football League Serie A in professional football players.

METHODS

In this retrospective study we analyzed records from media-based platform (Trasfermarkt, https://www.transfermarkt.com), describing the epidemiology of muscle injuries before and after the first COVID-19 lockdown phases in Italian professional football players. We also classified the severity of the injury as the number of missing days from participation.

RESULTS

We assessed a lower prevalence of post-lockdown injuries, albeit showing a similar injury rate at 1000 game-hours (pre-lockdown: 16.9 [13.0-20.7], post-lockdown: 15.5 [9.9-21.1]; RR: 0.92 [0.46-1.8]). All risk ratios for injury rate were not significantly different (p> .05) between pre- and post-lockdown.

CONCLUSIONS

The incidence of muscle injuries has not significantly changed after the first COVID-19 lockdown in Italian professional soccer players. Recognizing injury rates might be crucial for physician to evaluate adequate preventive measures.

Boost Tendon/Ligament Repair With Biomimetic and Smart Cellular Constructs

Tendon and ligament are soft connective tissues that play essential roles in transmitting forces from muscle to bone or bone to bone. Despite significant progress made in the field of ligament and tendon regeneration over the past decades, many strategies struggle to recapitulate basic structure-function criteria of native ligament/tendon. The goal here is to provide a fundamental understanding of the structure and composition of ligament/tendon and highlight few key challenges in functional regeneration of these connective tissues. The remainder of the review will examine several biomaterials strategies including biomimetic scaffold with non-linear mechanical behavior, hydrogel patch with anisotropic adhesion and gene-activated scaffold for interactive healing of tendon/ligament. Finally, emerging technologies and research avenues are suggested that have the potential to enhance treatment outcomes of tendon/ligament injuries.

Current perspectives and clinical practice of physiotherapists on assessment, rehabilitation, and return to sport criteria after anterior cruciate ligament injury and reconstruction. An online survey of 538 physiotherapists

OBJECTIVES

To evaluate the perspectives and clinical practice of physiotherapists regarding rehabilitation after anterior cruciate ligament reconstruction (ACLR).

DESIGN

Online survey.

SETTING

Survey platform.

PARTICIPANTS

Greek physiotherapists.

OUTCOME MEASURES

The survey consisted of 7 sections: participant demographics, importance of ACLR rehabilitation, clinical measurements, practice, criteria to progress rehabilitation, return to running and return to sport.

RESULTS

Significant variability in measures and criteria used for clinical decision-making were found including: limb symmetry in strength and function, knee range of motion and effusion, progression, and return to sport criteria. The majority of the practitioners (28.3%) extrapolate knee strength from hop capacity. Return to running ranged from 3 to 5 months post-operatively reflecting that this was tied to physical capacities, not time from surgery. 70.0% of the Greek physiotherapists would allow return to sport ≤9 months after ACLR. Agreement was found in using: physical measures, function, and dynamic stability in ACLR rehabilitation, but the mode and interpretation varied substantially. Less than 29.0% of the physiotherapists reported using patient-reported outcome measures in their decision-making.

CONCLUSION

Current ACLR rehabilitation practices in Greece are largely not aligned with the contemporary scientific evidence and guidelines.

The importance of biomechanical assessment after Return to Play in athletes with ACL-Reconstruction

BACKGROUND

Barriers to successful return to previous level of activity following Anterior Cruciate Ligament Reconstruction (ACLR) are multifactorial and recent research suggests that athletic performance deficits persist after completion of the rehabilitation course in a large percentage of patients.

RESEARCH QUESTION

Do technology-based biomechanical assessments reveal underneath differences in both recreational and competitive athletes in Return to Play after ACL-Reconstruction?

METHODS

Thirty soccer athletes (26.9 ± 5.7 years old, male) with ACL injury were surgically treated with all-inside technique and semitendinosus tendon autograft. Before 2 years from surgery, they were called back for clinical examination, self-reported psychological scores, and biomechanical outcomes (balance, strength, agility and velocity, and symmetry). Athletes were classified into recreational (n = 15) and competitive (n = 15) according to the self-reported Return to Play Level based on the TALS post-injury. Nonparametric statistical tests have been adopted for group comparisons in terms of age, concomitant presence of meniscus tear, injury on dominant leg, presence of knee laxity, presence of varus/valgus, body sides, and return to different levels of sports.

RESULTS

Competitive athletes showed better in terms of strength (45.3 ± 5.4 W kg^-1 vs 39.3 ± 3.4 W kg^-1, P ≤ 0.01) associated with good self-reported outcomes (TLKS, CRSQ) and low fear of reinjury (TSK). However, all the athletes had a functional deficit in at least one subtest, and a safe return to sports could not have been recommended. Our findings confirmed that demographics, physical function, and psychological factors were related to playing the preinjury level sport at mean 2 years after surgery, supporting the notion that returning to sport after surgery is multifactorial.

SIGNIFICANCE

A strict qualitative and quantitative assessment of athletes' status should be performed at different follow-ups after surgery to guarantee a safe and controlled RTP.

Surgical Timing Does Not Interfere on Clinical Outcomes in Combined Reconstruction of the Anterior Cruciate Ligament and Anterolateral Ligament: A Comparative Study With Minimum 2-Year Follow-Up

PURPOSE

To compare the functional outcomes, knee stability, failure rate and complication rates of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction with hamstrings grafts between acute and chronic cases.

METHODS

Consecutive patients who underwent combined ACL and ALL reconstruction with hamstrings grafts were evaluated. Patients operated on less than 8 weeks after injury were allocated to group 1, and the others were allocated to group 2. Demographic data, knee stability, and functional outcomes of the 2 groups were evaluated.

RESULTS

Thirty-four patients in the acute group and 96 in the chronic group were evaluated. The follow-up time was similar between the groups (28.7 ± 5.2 [24-43] months vs 29.4 ± 7.2 [24-58] months; P = 0.696). No differences were found between the groups in age, sex, trauma mechanism, presence of knee hyperextension, graft diameter, and meniscal injuries. There was no difference between the groups in the postoperative KT-1000 and in the pre- or postoperative pivot shift. The preoperative KT-1000 was higher in group 2 (7.9 ± 1.1 vs 7.4 ± 1.2; P = 0.031). There were no differences in the International Knee Documentation Committee or Lysholm. Three (2.3%) patients developed failure, 1 (2.9%) in group 1 and 2 (2.1%) in group 2. The total complication rate was 10% and did not differ between the groups.

CONCLUSIONS

Combined ACL and ALL reconstruction has similar outcomes in patients undergoing surgery in the acute and chronic phases. Patients with chronic injury have similar knee stability, functional scores, and failure rates as acute-injury patients, and patients with acute injury have no more complications than chronic patients.

LEVEL OF EVIDENCE

Level III, retrospective comparative therapeutic trial.

High rate of second ACL injury following ACL reconstruction in male professional footballers: an updated longitudinal analysis from 118 players in the UEFA Elite Club Injury Study

Background

Studies on subsequent anterior cruciate ligament (ACL) ruptures and career length in male professional football players after ACL reconstruction (ACLR) are scarce.

Aim

To investigate the second ACL injury rate, potential predictors of second ACL injury and the career length after ACLR.

Study design

Prospective cohort study.

Setting

Men’s professional football.

Methods

118 players with index ACL injury were tracked longitudinally for subsequent ACL injury and career length over 16.9 years. Multivariable Cox regression analysis with HR was carried out to study potential predictors for subsequent ACL injury.

Results

Median follow-up was 4.3 (IQR 4.6) years after ACLR. The second ACL injury rate after return to training (RTT) was 17.8% (n=21), with 9.3% (n=11) to the ipsilateral and 8.5% (n=10) to the contralateral knee. Significant predictors for second ACL injury were a non-contact index ACL injury (HR 7.16, 95% CI 1.63 to 31.22) and an isolated index ACL injury (HR 2.73, 95% CI 1.06 to 7.07). In total, 11 of 26 players (42%) with a non-contact isolated index ACL injury suffered a second ACL injury. RTT time was not an independent predictor of second ACL injury, even though there was a tendency for a risk reduction with longer time to RTT. Median career length after ACLR was 4.1 (IQR 4.0) years and 60% of players were still playing at preinjury level 5 years after ACLR.

Conclusions

Almost one out of five top-level professional male football players sustained a second ACL injury following ACLR and return to football, with a considerably increased risk for players with a non-contact or isolated index injury.

EPIDEMIOLOGY OF ANTERIOR CRUCIATE LIGAMENT INJURY IN SOCCER PLAYERS IN THE BRAZILIAN CHAMPIONSHIP

OBJECTIVE

To evaluate and collect epidemiological data on injuries of the anterior cruciate ligament of the knee in professional soccer players of the Brazilian Championship.

METHODS

Transversal study, with information extracted from the online data platform www.transfermrkt.com.br (Transfermarkt GmbH & Co. KG), with 5 seasons (2015 - 2019) of the Brazilian championship series A and B being analyzed and revised by 3 researchers.

RESULTS

52 injuries of the anterior cruciate ligament were detected, with a mean age of 26,3 years, time off due to injury of 244.5 ±31.6 days, regardless of the division. Forwarders and defenders had the highest incidences of injury without statistically significant difference, but they had greater chances than goalkeepers, left/right backs and midfielders.

CONCLUSION

The incidence of injury to the anterior cruciate ligament of the knee in professional football players in the first and second divisions of the Brazilian soccer championship between 2015 and 2019 is 0.414 per 1,000 hours of play, a value similar to described in the literature. The incidence of the injury varies according to the player's field position, being the forwarders and defenders the most injured players. Level of Evidence II, Retrospective study.

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.