Return to Play and Player Performance After Anterior Cruciate Ligament Injury in Elite Australian Rules Football Players

Epidemiology of cruciate ligament reconstruction in the Australian Defence Force and predictors of outcome

BACKGROUND

The ability to predict the risk of poor outcome following knee cruciate ligament reconstruction in the Australian Defence Force (ADF) population would help direct individual rehabilitation programmes and workforce planning. This study describes the epidemiology of cruciate ligament reconstruction in the ADF and demonstrates the use of Bayesian networks (BN) to predict the likelihood of fitness for ongoing service under different scenarios.

METHODS

Members who had knee cruciate ligament reconstruction through ADF were identified from billing data and matched to electronic medical records to extract demographic and clinical data. Outcome measure was medical fitness for ADF service up to 24 months after reconstruction. BN models were used to compare outcomes between (1) age groups according to military service, and (2) sexes according to body mass index (BMI).

RESULTS

From November 2012 to June 2019, a total of 1199 individuals had knee cruciate ligament reconstruction (average 169 reconstructions/year). Following reconstruction and rehabilitation, 89 (7.4%) were medically unfit for service. Scenario analysis using a tree-augmented naïve BN model showed that, compared with Navy and Air Force, Army members had a higher probability of being unfit in those aged <35 years and a lower probability in those aged ≥35 years. In both sexes, those with obese BMI had the greatest probability of being unfit.

CONCLUSION

While most ADF members were fit for ongoing military service following cruciate ligament reconstruction, service type, age, sex and BMI influenced outcome. BNs provided an interactive and intuitive method to demonstrate the impact of different variables on the outcome.

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.

Effects of a proprioceptive focal stimulation (Equistasi®) on reducing the biomechanical risk factors associated with ACL injury in female footballers

Introduction

Football presents a high rate of lower limb injuries and high incidence of Anterior Cruciate Ligament (ACL) rupture, especially in women. Due to this there is the need to optimize current prevention programs. This study aims to verify the possibility to reduce the biomechanical risk factors associated with ACL injury, through the application of proprioceptive stimulation by means of the Equistasi® device.

Methods

Ten elite female footballers were enrolled and received the device for 4 weeks (5 days/week, 1h/day). Athletes were assessed directly on-field at four time points: T0 and T1 (evaluation without and with the device), T2 (after 2 weeks), T4 (after 4 weeks) while performing two different tasks: Romberg Test, and four sidestep cutting maneuvers bilaterally. Seven video cameras synchronized with a plantar pressure system were used, thirty double colored tapes were applied on anatomical landmarks, and three dimensional coordinates reconstructed. Vertical ground reaction forces and center of pressure data were extracted from the plantar pressure insoles. Hip, knee, and ankle flexion-extension angles and moments were computed as well as abd-adduction joint torques. From the Romberg Test both center of pressure descriptive variables and frequency analysis parameters were extracted. Each variable was compared among the different time frames, T1, T2 and T4, through Friedman Test for non-parametric repeated measures (p<0.05); Wilcoxon Signed Rank Test was used for comparing variables between T0 and T1 (p<0.05) and across the different time frames as follows: T1-T2, T2-T4 and T1-T4.

Results

Statistically significant differences in both posturographic and biomechanical variables between the assessment at T0 and T1 were detected. Reduced hip and knee abduction torques were revealed in association with reduced both ground reaction forces and ankle dorsiflexion torque from T1 up to T4.

Discussion

The proprioceptive stimuli showed to have the potential to improve cutting biomechanics mainly with respect to the ligament and quadriceps dominance theories. Results of the present study, even if preliminary and on a small sample size, could be considered promising towards the inclusion of proprioceptive training in injury prevention programs.

Anticipatory effects on side-step cutting biomechanics in Women's Australian Football League players

Objectives

Reactive side-step cutting manoeuvres are linked to anterior cruciate ligament (ACL) injuries in Women's Australian Football League (AFLW) matches. We explored knee joint moments and ground reaction forces (GRFs) in AFLW players when performing anticipated and unanticipated side-stepping.

Methods

Sixteen AFLW players (age=25.3±4.2 years; height=1.71±0.06 m; mass=68.4±4.7 kg) completed anticipated and unanticipated side-stepping trials during which full-body three-dimensional kinematics and kinetics were recorded. One-dimensional statistical parametric mapping paired t-tests were used to compare three-dimensional knee moments during weight acceptance and GRFs during the stance phase between anticipated and unanticipated conditions.

Results

Unanticipated side-stepping incurred lower knee flexion (18%-39% of stance, p<0.01) and abduction (11%-24% of stance, p<0.01) moments. Braking and propulsive GRFs were lower and higher, respectively, across the majority of stance phase (6%-90% of stance, p<0.01) in unanticipated side-stepping. Vertical GRFs were lower in unanticipated side-stepping in the early stance phase (14%-29% of stance, p<0.01).

Conclusion

Contrary to existing literature, AFLW players exhibited knee joint moments associated with reduced ACL loading when performing unanticipated side-stepping. Players appeared to adopt a 'cautious' approach to the unanticipated side-step (ie, decelerating at the change of direction), by reducing braking and vertical GRFs in the early stance phase of cutting. This approach may be implausible to employ or detrimental to performance during matches. AFLW ACL injury prevention programmes may be enhanced with greater exposure to scenarios that replicate reactive match-play demands when aiming to improve side-stepping biomechanics.

Preoperative predictors for return to physical activity following anterior cruciate ligament reconstruction (ACLR): a systematic review

BACKGROUND

Rates of return to physical activity after anterior cruciate ligament reconstruction surgery are sub-optimal. Optimising presurgical treatment may improve return rates. The purpose of this systematic review was to identify modifiable preoperative predictors for return to physical activity after anterior cruciate ligament reconstruction.

METHODS

Seven electronic databases (CINAHL, MEDLINE and SPORTDiscus via EBSCOhost, AMED, PsycINFO and EMBASE via OVID and Web of Science) were searched from inception to 31 March 2023. The population of focus was adults aged 18-65 who had undergone primary anterior cruciate ligament reconstruction. Studies needed to identify at least one potential modifiable preoperative predictor variable and the relationship between the predictor(s) and return to physical activity. All time-points of assessment and study designs were included. Data extraction was completed by one reviewer and verified by a second reviewer. Two reviewers completed the risk of bias assessment using the Quality in Prognostic Studies tool and Grading of Recommendations Assessment, Development and Evaluation system.

RESULTS

The search identified 2281 studies, eight met the inclusion criteria. Five studies scored 'high', and three studies scored 'moderate' risk-of-bias. All preoperative predictors were of very low-quality evidence. Five different outcome measures were used to assess return to physical activity including Tegner, Marx, Physical Activity Scale, return to play at the elite level and return to preinjury level (undefined). This was measured between 1- and 10-years post-surgery. Nine preoperative physical, six psychosocial and five demographic/clinical factors were assessed and four were found to be predictive. These included quadriceps strength, psychological profile, patient estimated ability to return and graft type (patella tendon, BPTB).

CONCLUSION

Very-low level evidence suggests that increasing quadriceps strength, managing patient expectations of their treatment outcomes, improving motivation to resume preinjury activity levels and considering the use of a BPTB graft will support return to physical activity after ACLR.

TRIAL REGISTRATION

This study was prospectively registered in PROSPERO: CRD 42020222567.

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.

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.

Video Analysis of Anterior Cruciate Ligament Injury Situations in the Women's Australian Football League

Anterior cruciate ligament (ACL) injury rates in the Women's Australian Football League (AFLW) are alarmingly high. Understanding injuries within their sporting context is important to develop effective injury prevention strategies, yet there is currently little knowledge of how ACL injuries occur to AFLW players. This study addressed the common scenarios and characteristics of ACL injuries in the AFLW.

Online match and AFLW club injury reports identified 38 ACL injury cases. After excluding injuries where footage was unavailable (i.e. training, pre-season games), a video analysis of 21 match ACL injuries from the 2017-2020 AFLW seasons was performed. We examined match characteristics, and the player's movements and body postures preceding and at the estimated time of injury. Descriptive frequencies and relative proportions were determined across the assessed categories.

Non-contact ACL injuries were frequently observed (n=13, 61.9%), while contact preceding the injury event (i.e. indirect contact) was also common (n=10, 47.6%). The most common game situation was direct defence (i.e. defending an opponent in possession) (n=14, 66.7%). Sidestep cutting was the most prevalent movement (n=11, 52.4%), with this commonly performed while applying defensive pressure (n=6 of 11, 54.6%).

Sidestep cutting when applying defensive pressure is the most common non-contact ACL injury scenario in the AFLW. Preceding contact potentially contributing to a player's loss of balance was another prominent AFLW scenario. AFLW players may benefit from injury prevention programs emphasising appropriate sidestep cutting technique during reactive defensive scenarios, and maintenance of lower limb postures known to withstand knee loading relative to the sporting task.

Rates and Determinants of Returning to Australian Rules Football in Male Nonprofessional Athletes After Anterior Cruciate Ligament Reconstruction

Background:

Return to sport is a goal for most patients who undergo anterior cruciate ligament (ACL) reconstruction. However, at a nonelite level, there are limited sport-specific data regarding rates or factors associated with return to play.

Purpose:

To report rates and determinants of returning to play Australian Rules football after ACL reconstruction in male nonprofessional athletes.

Study Design:

Case-series; Level of evidence, 4.

Methods:

A total of 354 male nonprofessional Australian Rules football players who had undergone primary ACL reconstruction were asked to complete detailed sports activity questions at 12 months and 2 to 5 years (mean, 3 years) after surgery. Rates of return to play were calculated for both timepoints, along with preoperative patient expectations and postoperative sport performance. The following predictors of return to play were examined: age at surgery; height; weight; frequency of weekly football participation; sport participation level; psychological readiness to return to sport; and knee-related quality of life. Further ACL injuries were also documented. Descriptive statistics were used to summarize return-to-play data and contingency analysis for predictors of return to sport.

Results:

The rate of return to any level of play was 35% (95% CI, 30%-41%; n = 284) at the 12-month follow-up and 78% (95% CI, 72%-83%; n = 233) at the 2- to 5-year follow-up. Overall, 64% (95% CI, 57%-70%) of the patients were able to return to their same or higher level of play. Before surgery, 92% of the patients expected to return to their same preinjury level of Australian Rules football participation. At the 2- to 5-year follow-up, 61% who returned to play felt that they could perform as well as they could before their ACL injury. A greater psychological readiness to return to sport preoperatively and higher level of sport participation were significant predictors of a return at 2 to 5 years. Further ACL injuries were sustained by 21% of the cohort (15% graft rupture; 6% contralateral ACL injury).

Conclusion:

Most male athletes who participate in Australian Rules football returned to some level of play after ACL reconstruction; however, only 64% returned to preinjury levels. Preoperative expectations were not met, and high reinjury rates are a cause for concern.

Anterior Cruciate Ligament Injuries in Australian Rules Football: Incidence, Prevention and Return to Play Outcomes

Australian Rules football is the most popular of the various codes of football played in Australia. During the game players perform frequent landing, cutting and pivoting manoeuvres that expose them to substantial risk for anterior cruciate ligament (ACL) injury. Recent years have seen the introduction of a professional women's league that has resulted in an exponential growth in the participation of women and girls in this sport. Unfortunately, there is a corresponding growth in ACL injury rates in female players. This review summarizes the incidence of ACL injury in both men's and women's Australian Rules football and reviews potential causative factors and risk reduction strategies. The final section takes an in depth look at return to sport outcomes after ACL reconstruction surgery in these populations. Whilst an ACL injury does not mean the end of a player's career in Australian football, it certainly presents a significant challenge in terms of return to preinjury levels of form and high rates of secondary and tertiary ACL injury are also a significant concern.

Return to Sport After ACL Reconstruction With a BTB Versus Hamstring Tendon Autograft: A Systematic Review and Meta-analysis

Background

Anterior cruciate ligament (ACL) tears are debilitating injuries frequently suffered by athletes. ACL reconstruction is indicated to restore knee stability and allow patients to return to prior levels of athletic performance. While existing literature suggests that patient-reported outcomes are similar between bone-patellar tendon-bone (BTB) and hamstring tendon (HT) autografts, there is less information comparing return-to-sport (RTS) rates between the 2 graft types.

Purpose

To compare RTS rates among athletes undergoing primary ACL reconstruction using a BTB versus HT autograft.

Study Design

Systematic review; Level of evidence, 4.

Methods

The MEDLINE, Embase, and Cochrane Library databases were searched, and studies that reported on RTS after primary ACL reconstruction using a BTB or HT autograft were included. Studies that utilized ACL repair techniques, quadriceps tendon autografts, graft augmentation, double-bundle autografts, allografts, or revision ACL reconstruction were excluded. RTS information was extracted and analyzed from all included studies.

Results

Included in the review were 20 articles investigating a total of 2348 athletes. The overall RTS rate in our cohort was 73.2%, with 48.9% returning to preinjury levels of performance and a rerupture rate of 2.4%. The overall RTS rate in patients after primary ACL reconstruction with a BTB autograft was 81.0%, with 50.0% of athletes returning to preinjury levels of performance and a rerupture rate of 2.2%. Patients after primary ACL reconstruction with an HT autograft had an overall RTS rate of 70.6%, with 48.5% of athletes returning to preinjury levels of performance and a rerupture rate of 2.5%.

Conclusion

ACL reconstruction using BTB autografts demonstrated higher overall RTS rates when compared with HT autografts. However, BTB and HT autografts had similar rates of return to preinjury levels of performance and rerupture rates. Less than half of the athletes were able to return to preinjury sport levels after ACL reconstruction with either an HT or BTB autograft.

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.

Making football safer for women: a systematic review and meta-analysis of injury prevention programmes in 11 773 female football (soccer) players

Objective

To evaluate the effects of injury prevention programmes on injury incidence in any women’s football code; explore relationships between training components and injury risk; and report injury incidence for women’s football.

Design

Systematic review and meta-analysis.

Data sources

Nine databases searched in August 2019.

Eligibility criteria

Randomised controlled trials evaluating any injury prevention programme (eg, exercise, education, braces) were included. Study inclusion criteria were: ≥20 female football players in each study arm (any age, football code or participation level) and injury incidence reporting.

Results

Twelve studies, all in soccer, met inclusion criteria, with nine involving adolescent teams (aged <18 years). All studies (except one) had a high risk of bias. Eleven studies examined exercise-based programmes, with most (9/11) including multiple (≥2) training components (eg, strength, plyometric, balance exercises). Multicomponent exercise programmes reduced overall (any reported) injuries (incidence rate ratio (IRR) 0.73, 95% CI 0.59 to 0.91) and ACL injuries (IRR 0.55, 95% CI 0.32 to 0.92). For exercise-based strategies (single-component and multicomponent), hamstring injuries were also reduced (IRR 0.40, 95% CI 0.17 to 0.95). While exercise-based strategies resulted in less knee, ankle and hip/groin injuries, and the use of multiple training components was associated with greater reductions in overall and knee injuries, further studies would be required to increase the precision of these results. The incidence of overall injuries in women’s football was 3.4 per 1000 exposure hours; with ankle injuries most common.

Conclusion

In women’s football, there is low-level evidence that multicomponent, exercise-based programmes reduce overall and ACL injuries by 27% and 45%, respectively.

PROSPERO registration number

CRD42018093527.

Playing Performance After Anterior Cruciate Ligament Reconstruction Among Australian Football League Players From 1999 to 2013

BACKGROUND

Achieving preinjury levels of athletic performance has been challenging for elite athletes after anterior cruciate ligament (ACL) reconstruction. Although a recent study found that 77% of Australian Football League (AFL) players who underwent ACL reconstruction from 1999 to 2013 returned to play at the highest level, the study did not indicate how consistently or well they were able to play.

PURPOSE

To identify the number of AFL players who returned to play consistently over 2 seasons after ACL reconstruction, compare their playing performance in these seasons with preinjury performance, and evaluate factors associated with returning to preinjury levels of performance.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Analysis included 104 AFL players who underwent ACL reconstruction between 1999 and 2013. All had played at least 10 AFL matches in 1 season before ACL injury. Ranking points, as devised by AFL statisticians, were used to measure individual playing performance.

RESULTS

Of the 104 players who played at least 10 matches in 1 season before ACL injury, 53 (51%) returned to play at least 10 matches in 2 seasons after surgery. Of these 53 players, 36 (68%) returned to their preinjury levels of performance. The 17 remaining players who did not return to their preinjury performance still performed comparably to the AFL average level after surgery. Players <25 years old (odds ratio = 2.9, P = .01) or <90 kg (odds ratio = 2.7, P = .03) had greater odds of returning to their preinjury levels of performance.

CONCLUSION

Returning to play on a consistent basis was a substantial challenge for AFL players after ACL reconstruction. However, among players who did return to play consistently over 2 seasons, their postsurgery average performance was comparable with the AFL average level of performance, and two-thirds returned to their preinjury levels of performance. Younger and lighter players were more likely to return to their preinjury levels of performance, possibly given the nature of AFL club playing list management decisions.

Eccentric knee flexor weakness in elite female footballers 1-10 years following anterior cruciate ligament reconstruction

OBJECTIVES

To determine eccentric knee flexor strength in elite female Australian Rules Football (ARF) players with and without a history of unilateral anterior cruciate ligament reconstruction (ACLR) using an ipsilateral semitendinosus graft.

DESIGN

Case-control.

SETTING

Elite ARF Women's competition.

PARTICIPANTS

Eighty-four elite female ARF players (mean age, 25 ± 4.9 years; height, 1.71 ± 0.73 m; weight, 67 kg ± 7.4 kg) with (n = 12) and without (n = 72) a history of unilateral ACLR in the previous 10 years.

MAIN OUTCOME MEASURES

Peak eccentric knee flexor force during the Nordic hamstring exercise (NHE).

RESULTS

Players with a history of unilateral ACLR displayed lower levels of eccentric knee flexor strength in their surgically reconstructed limb than their uninjured contralateral limb (mean difference -53.77 N, 95% CI = -85.06 to -24.27, d = -0.51) and compared to the limbs of players with no history of injury (mean difference = -46.32 N, 95% CI = -86.65 to -11.13, d = -0.73).

CONCLUSION

Elite female ARF players with a history of unilateral ACLR display deficits in eccentric knee flexor strength in their surgically reconstructed limb for up to 10 years following surgery.

Fifteen-Year Audit of Anterior Cruciate Ligament Reconstructions in the Australian Football League From 1999 to 2013: Return to Play and Subsequent ACL Injury

BACKGROUND

Anterior cruciate ligament (ACL) injury has been a major cause of missed game time among Australian Football League (AFL) players. Return to play after ACL reconstruction is not always achieved, even among elite athletes. The rate of subsequent ACL injury in the AFL from 1990 to 2000 was high as compared with that of other elite sports.

PURPOSE

To determine the rates of return to play and subsequent ACL injury after ACL reconstruction among AFL players from 1999 to 2013 and to explore factors associated with differing rates of return to play and subsequent ACL injury.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 158 AFL players who underwent ACL reconstruction were identified from a prospectively maintained registry of AFL player injuries. Further data were gathered from official playing statistics, surgical records, and structured phone interviews.

RESULTS

The rate of return to play after an initial ACL injury was 77% (121 of 158 players). Greater preinjury playing experience and earlier selection in the AFL draft were associated with higher rates of return to play. The rate of subsequent ACL injury to either knee was 30% (48 of 158 players) and was especially high among players aged <21 years (23 of 46 players, 50%). After subsequent ACL injury, 34 of 48 players (71%) returned to play. In primary ACL reconstruction, the use of Ligament Augmentation and Reconstruction System grafts resulted in a faster return to play ( P = .001) but had a higher risk of subsequent revision reconstruction (risk ratio = 2.8, P = .048). Family history of ACL injury was associated with an increased risk of subsequent contralateral ACL injury (risk ratio = 3.8, P = .002).

CONCLUSION

Most AFL players who underwent ACL reconstruction returned to play at least 1 AFL match. The high rate of subsequent ACL injury among AFL players demonstrates the highly demanding nature of Australian football, particularly at the elite level. The risk factors for subsequent ACL injury should be considered carefully when treatment and rehabilitation decisions are made for these high-demand athletes.

Proprioceptive Changes in Bilateral Knee Joints Following Unilateral Anterior Cruciate Ligament Injury in Cynomolgus Monkeys

BACKGROUND The anterior cruciate ligament (ACL) is one of the most important structures maintaining stability of knee joints, and the proprioception of the ACL plays a key role in it. If the ACL is injured in the unilateral knee joint, it changes nerve electrophysiology, morphology, and quantity of the proprioceptors in the bilateral ACL. The aim of this study was to explore the proprioceptive changes in the bilateral knee joints following unilateral ACL injury, and to provide a theoretical foundation and ideas for clinical treatment. MATERIAL AND METHODS Nine normal cynomolgus monkeys were chosen and used to developed a model of unilateral ACL injury, and 3 monkeys without modeling were used as blank control. At the 4th, 8th, and 12th weeks, the changes in ACL nerves were inspected using electrophysiology [somatosensory evoked potentials (SEPs) and motor nerve conduction velocity (MCV)], and the changes of morphology and quantity of the proprioceptors in ACL were observed and measured under gold chloride staining. RESULTS On the injured and contralateral knee joints, the incubations were extended and the amplitudes were decreased over time. In addition, with the extension of time, the total number of proprioceptors in the ACL decreased, and the variable number of proprioceptors in the ACL increased. CONCLUSIONS ACL injury leads to attenuation of proprioception on the injured side, and also leads to the attenuation of proprioception on the contralateral side, and there is a tendency could get worse over time.