Activity and functional readiness, not age, are the critical factors for second anterior cruciate ligament injury - the Delaware-Oslo ACL cohort study

More knee reinjuries after ACL reconstruction compared to nonsurgical treatment of the ACL. A 2-year follow-up of the NACOX prospective cohort study

PURPOSE

To describe knee reinjuries and surgeries within 2 years after an acute anterior cruciate ligament (ACL) injury, in patients treated with or without ACL reconstruction (ACLR).

METHODS

Two years follow-up of 275 patients (52% females, mean age 25.2 [SD 7.0] years) about knee reinjuries and surgeries were analysed from the prospective NACOX cohort study, aiming to describe recovery after an acute ACL injury treated according to clinical routine. Knee reinjury was defined as increase or new symptoms due to new trauma. At 2 years after injury, 169 (61%) had undergone an ACLR. Results are presented with descriptive statistics and risk ratios (RR).

RESULTS

Thirty-two patients sustained reinjuries within 2 years; 6 in the non-ACLR group, and 26 in the ACLR group (7 before and 19 after ACLR). Twelve patients in the ACLR group sustained a graft rupture and three did an ACL revision. Patients with non-ACLR, aged 21-25 years, had a 5.9-fold higher risk for reinjury than those aged 15-20 years (RR 5.9 [1.3-26.9]; p = 0.012). Twenty-four patients had surgery in the non-ACLR group and 36 patients in the ACLR group (excluding primary ACLR), where six were before ACLR and 30 were after ACLR.

CONCLUSION

Twelve percent sustained a knee reinjury and 21% underwent knee surgery within 2 years after the index ACL injury. There was a higher reinjury incidence in the ACLR group, but no difference in incidence of surgeries. Thus, ACLR did not reduce the risk of traumatic reinjuries or surgeries, which is important for treatment decision considerations.

LEVEL OF EVIDENCE

Level I.

[Research progress of suture augmentation in anterior cruciate ligament reconstruction]

Objective

To summarize the research progress of suture augmentation (SA) in anterior cruciate ligament (ACL) reconstruction.

Methods

A comprehensive review of recent literature about SA in ACL reconstruction at home and abroad was conducted. The efficacy of SA in ACL reconstruction was evaluated by examining the definition, biomechanics, and histological studies of SA, along with its clinical application status in ACL reconstruction.

Results

SA demonstrates significant advantages in enhancing the biomechanical stability of ACL grafts, reducing the risk of re-rupture, and accelerating postoperative recovery. Specifically, SA improves graft stiffness, ultimate failure strength, and cyclic stability, thereby diminishing the risk of early postoperative failure and joint instability. Histologically, it fosters remodeling and tendon-bone integration through early load-sharing mechanisms; however, stress shielding may interfere with natural remodeling processes, warranting further attention. Clinically, SA reduces graft failure rates and the need for revision surgeries, markedly improving knee joint stability and functional recovery in young patients. Nevertheless, its impact on graft maturation and potential complications remains controversial.

Conclusion

Despite the many advantages of SA in ACL reconstruction, future endeavors should focus on optimizing tensioning techniques, developing bioactive materials, and conducting large-scale randomized controlled trials to further elucidate its clinical value and scope of applicability, providing a more reliable solution for ACL reconstruction.

Precision Rehabilitation After Youth Anterior Cruciate Ligament Reconstruction: Individualized Reinjury Risk Stratification and Modifiable Risk Factor Identification to Guide Late-Phase Rehabilitation

Background

After anterior cruciate ligament (ACL) reconstruction, adolescent athletes have a high risk of second ACL injuries, and revision ACL reconstruction is associated with increased medical costs, reduced activity levels, chronic knee pain, and higher rates of knee osteoarthritis, making the prevention of a reinjury a priority. While athlete clearance protocols and algorithms exist, the current methods of identifying the reinjury risk have limited predictive accuracy and are largely based on nonmodifiable risk factors, which limit their clinical application.

Purpose

The goal of this study was to develop an ACL reinjury risk prediction (ACL-RRP) model capable of accurately classifying an individual patient's risk, identifying modifiable risk factors, and ranking these factors in the order of importance and ability to be modified.

Study Design

Cohort study (Diagnosis); Level of evidence, 2.

Methods

A clinician-informed approach was utilized to develop the prediction model and an interpretable output system. The primary outcome variable was the likelihood of sustaining a repeat ACL injury. The data were split into training (80% [n = 628]) and holdout (20% [n = 158]) datasets to train and subsequently validate the model. The accuracy of classification was identified by the sensitivity, specificity, positive/negative predictive values, and odds ratio.

Results

The final model included 33 predictor variables, 23 of which are modifiable. The model adjusted the weight of the risk classification and risk factors (predictor variables) on a case-by-case basis. The model demonstrated a sensitivity of 94% and a specificity of 76%. Patients classified as being high risk had 4.5 times the risk of repeat ACL injuries compared with those classified as being low risk.

Conclusion

This clinician-informed ACL-RRP model demonstrated a high degree of accuracy when classifying patients as having a high or low risk of repeat ACL injuries and generated patient-specific modifiable risk factors to guide ongoing rehabilitation or patient education to achieve the goals of reducing the ACL reinjury risk.

Young age and return to play increase the likelihood of subsequent ACL reconstruction in football players: Data from the Swedish National Knee Ligament Registry

PURPOSE

To compare football players who have undergone one anterior cruciate ligament (ACL) reconstruction (ACLR) with those who have undergone a subsequent ACLR (revision or contralateral) regarding (1) demographics, (2) football-related factors and (3) injury-specific data.

METHODS

Players who voluntarily completed a football-specific questionnaire available at the Swedish National Knee Ligament Registry website between April 2017 and September 2020 at the time of their primary ACL injury were included in the study. The questionnaire covered demographics, football-related activities and injury-specific factors. Subsequent ACLR registrations within 4 years of the primary ACLR were identified in December 2023. Data on game participation post-primary ACLR were retrieved from the Swedish Football Association's administrative system in September 2022.

RESULTS

A total of 992 football players (66% men) were included, of whom 99 (10%) were registered for subsequent ACLRs. Univariable analysis showed that the following factors significantly increased the odds of a subsequent ACLR: female sex, younger age, a lower weight and body mass index, fewer years played, use of knee control exercises during warm-up, more likely to plan a return to football, more game participation registered following the primary ACLR, and shorter time between injury and ACLR. Multivariable logistic regression analysis indicated that the odds of undergoing subsequent ACLR decreased significantly with each additional year of age (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.83‒0.92, p < 0.01). Players using knee control exercises during warm-up (OR, 1.71; 95% CI, 1.08‒2.72, p = 0.02), planning to return to football (OR, 2.74; 95% CI, 1.27‒5.91, p = 0.01), and participating in games after primary ACLR (OR, 1.81; 95% CI, 1.13‒2.91, p = 0.01) increased the odds of undergoing a subsequent ACLR.

CONCLUSIONS

Younger age and returning to play after an ACLR significantly increase the likelihood of undergoing a subsequent ACLR in football players.

LEVEL OF EVIDENCE

Level IV.

Which technique provides more benefits in return to sports and clinical outcomes after anterior cruciate ligament reconstruction: Double-bundle or single-bundle? A randomized controlled study

BACKGROUND

The achievement of an optimal return to sport (RTS) has remained a key goal after sports-related injuries, with the ongoing debate on the effectiveness of different surgical approaches for anterior cruciate ligament (ACL) rupture. This study aims to assess clinical outcomes and RTS across various surgical methods, such as anatomical single-bundle reconstruction (ASBR), central-axial single-bundle reconstruction (CASBR), and double-bundle reconstruction (DBR).

METHODS

A randomized clinical trial was conducted, comprising 191 patients who underwent ACL rupture. These patients were divided into three groups based on the ACL reconstruction techniques they received (ASBR, CASBR, DBR). Over the 2-year follow-up period, the study assessed RTS through four single-hop tests, isokinetic extension tests, and limb asymmetry indices. Postoperative graft status was determined using the signal-to-noise quotient (SNQ), while knee function was evaluated using the International Knee Documentation Committee 2000 (IKDC-2000) score, Lysholm score, Tegner score, and degree of knee laxity. A binary logistic regression model was developed to forecast the factors influencing ideal RTS.

RESULTS

DBR (67.63%) and CASBR (58.00%) exhibited higher RTS passing rates compared to ASBR (30.39%; χ2 = 19.57, P <0.05). Quadriceps strength symmetry in the lower limbs was identified as the key determinant of RTS (χ2 = 17.08, P <0.05). The RTS rate was influenced by SNQs of the graft's tibial site (odds ratio: 0.544) and quadriceps strength of the reconstructed knee joint at 60°/s (odds ratio: 6.346). Notably, the DBR group showed enhanced knee stability, evidenced by superior results in the Lachman test (χ2 = 13.49, P <0.01), objective IKDC-2000 (χ2 = 27.02, P = 0.002), and anterior instability test (χ2 = 9.46, P <0.01). Furthermore, DBR demonstrated superior clinical outcomes based on the Lysholm score (DBR: 89.57 ± 7.72, CASBR: 83.00 ± 12.71, ASBR: 83.21 ± 11.95; F = 10.452, P <0.01) and IKDC-2000 score (DBR: 90.95 ± 7.00, CASBR: 84.64 ± 12.68, ASBR: 83.63 ± 11.41; F = 11.78, P <0.01).

CONCLUSION

For patients with ACL rupture, more ideal RTS rate and clinical outcomes were shown in the DBR group than in the ASBR and CASBR groups. Autograft status and quadriceps strength are postively related to RTS.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05400460).

An 8-week physiotherapist-led return to sport group program after anterior cruciate ligament reconstruction improves measures of physical and psychological function: A case series

BACKGROUND

Low return to competitive sport, high reinjury rates and long-term functional impairment of anterior cruciate ligament reconstruction (ACLR) present significant challenges for patients. A program that facilitates a safe return to sport (RTS) following ACLR could potentially improve outcomes.

STUDY DESIGN

Case Series.

METHODS

Sixty participants (median 20-years-old (13-36), 43 males, 18 females, median 7.5 months (4-25) post-ACLR) completed an eight-week exercise program. A battery of physical tests and patient-reported outcome measures were assessed pre and post-program. The number of participants passing RTS criteria was evaluated, and RTS rates were determined. The correlation between the ACL-RSI and measures of physical function was explored.

RESULTS

Improvements in all isometric strength, hop tests, running T-test, and patient reported outcome measures were seen post-program. Five (8%) participants successfully passed all RTS criteria and eighty-five percent of participants returned to their previous level of sport. The ACL-RSI and the IKDC showed correlation across all time points (pre rs = 0.49; post rs = 0.40; change r = 0.40).

CONCLUSIONS

Our study demonstrated improvements in all RTS criteria tests upon completing the 8-week rehabilitation program; however, few participants (8%) passed all RTS criteria. Psychological readiness is more closely related to patient-reported function than functional tests.

Higher Unilateral Muscle Imbalance at the Contralateral Knee 6 Months after Anterior Cruciate Ligament Reconstruction

There are a considerable number of patients who, after anterior cruciate ligament reconstruction (ACL), suffer from relapses or reduced performance. Data collected from isokinetic dynamometry can provide useful information on the condition of the knee during rehabilitation. Seventy-one young sports patients with ACL reconstruction performed concentric (CON) isokinetic dynamometry (CON/CON 90°/s and CON/CON 240°/s) to assess the muscle strength of the quadriceps (Q) and hamstrings (H) in both knees at 6 months after ACL reconstruction. Limb symmetry index (LSI) and the H/Q ratio were calculated. Comparative statistical tests and multivariate regression were performed. At 90°/s, 57 patients (80.3%) had an LSI below 90% for quadriceps and 28 (60.6%) for hamstring. The number of imbalanced patients according to H/Q ratio was higher in the non-operated knee (n = 56, 78.9%) (p < 0.001). At 240°/s, 49 cases (69.1%) had LSI values above 90% for quadriceps and 37 (52.1%) for hamstrings. Regarding H/Q, imbalanced cases were higher in the non-operated limb (n = 60, 84.5%) (p < 0.001). Strength data at 6 months after ACL reconstruction and post-operative rehabilitation indicated greater unilateral (H/Q) muscle imbalance in the non-operated knee than in the operated knee. Most patients did not achieve the adequate LSI values.

Risk-factor analysis of the proximal tibia morphology for secondary ipsilateral injury after anterior cruciate ligament reconstruction: A retrospective cross-sectional study

Many studies have reported the risk factors associated with primary anterior cruciate ligament (ACL) injury. However, few studies have focused on the bony morphology of secondary ipsilateral injury after ACL reconstruction. This study aimed to investigate the morphological risk factors of the proximal tibia contributing to secondary ipsilateral injury after ACL reconstruction. Twenty patients who were selected from secondary ipsilateral injury after ACL reconstruction between January 2015 and May 2020 were included in the secondary injury group. They were matched in a 1:2 ratio to the control group, which underwent primary ACL reconstruction during the same period and did not experience reinjury at the minimum 2-year follow-up, based on age, gender, and body mass index. All parameters, including medial tibial posterior slope, lateral tibial posterior slope (LTPS), medial tibial plateau depth, and lateral tibial plateau height, were recorded by using magnetic resonance imaging. Binary logistic regression analysis and receiver operator characteristic curves were conducted to explore the risk factors for reinjury and determine the cutoff value for the significant parameter. The LTPS was significantly larger in the secondary injury group than in the control group (9.6 ± 1.5° to 7.0 ± 1.4°, P < .001), and there was no significant difference in the medial tibial posterior slope, medial tibial posterior slope, and lateral tibial plateau height between the 2 groups (P > .05). The LTPS was found to be an independent risk factor for secondary ipsilateral injury after ACL reconstruction (odds ratio = 3.220, 95% confidence interval = 1.904-5.446, P < .001). The cutoff value of the LTPS was 8.8°, with a sensitivity of 91.7% and a specificity of 81.2%. The LTPS could be a unique predictor of secondary ipsilateral injury after ACL reconstruction. Orthopedists should implement effective measurements during primary reconstruction when the LTPS is >8.8°.

Functional Return-to-Sport Testing Demonstrates Inconsistency in Predicting Short-Term Outcomes Following Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the relationship between functional testing at the time of return to sport (RTS) and short-term outcomes, such as second anterior cruciate ligament (ACL) tear and return to a preinjury level of sport, among athletes who underwent anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic literature search was performed in MEDLINE, EMBASE, Scopus, and Web of Science to identify studies examining athletes who underwent functional RTS testing and were followed for at least 12 months following ACLR. Studies were screened by 2 reviewers. A standardized template was used to extract information regarding study characteristics, ACLR information, functional test results, and risk factors associated with retear or reduced RTS.

RESULTS

Of the 937 studies identified, 22 met the inclusion criteria. The average time between ACLR and RTS testing was 8.5 months. Single leg hop for distance performance had no association with retear risk in any study and no association with RTS rates in most studies. Quadriceps strength had conflicting results in relation to retear risk, whereas it had no relationship with RTS rates. Rates of reinjury and RTS were similar between patients who passed and did not pass combined hop and strength batteries. Asymmetric knee extension and hip moments, along with increased knee valgus and knee flexion angles, demonstrated increased risk of retear.

CONCLUSIONS

Individual hop and strength tests that are often used in RTS protocols following ACLR may have limited and inconsistent value in predicting ACL reinjury and reduced RTS when used in isolation. Combined hop and strength test batteries also demonstrate low sensitivity and negative predictive value, highlighting conflicting evidence to suggest RTS testing algorithm superiority.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Double-Leg and Single-Leg Jump Test Reference Values for Athletes With and Without Anterior Cruciate Ligament Reconstruction Who Play Popular Pivoting Sports, Including Soccer and Basketball: A Scoping Review

OBJECTIVE: To synthesize and present reference values for double-leg and single-leg jump tests in healthy athletes who play pivoting sports, and athletes with anterior cruciate ligament reconstruction (ACLR) who play pivoting sports. DESIGN: Scoping review. LITERATURE SEARCH: We searched PubMed, the Cochrane Library, MEDLINE, Embase, and Web of Science until April 7, 2023. STUDY SELECTION CRITERIA: We included reference values in 2 different categories: (1) double-leg and/or single-leg jump test outcomes in pivoting-sport athletes with ACLR at a specific time point during rehabilitation, and (2) double-leg and/or single-leg jump test outcomes in healthy pivoting-sport athletes. DATA SYNTHESIS: We performed data synthesis for reference values from double-leg jump tests (squat jump and countermovement jump) and single-leg jump tests (vertical hop, single hop for distance, triple hop for distance, crossover hop for distance, medial triple hop for distance, lateral triple hop for distance, 6-m timed hop, side hop, drop jump, and 10-second repeated hop) that were performed according to a standardized test description. We summarized the data for type of sport, sex, sport participation level, and age group. RESULTS: Of the 27 included studies, nine reported reference values from healthy soccer players, six from healthy basketball players, and eleven from other healthy pivoting-sport athletes. LSI dominant/nondominant (LSI-D/ND) ranged between 97% and 106% for healthy soccer players, and between 99% and 120% for healthy basketball players. Four studies reported reference values from pivoting-sport athletes with ACLR from 7 to 10 months postsurgery. CONCLUSION: This scoping review summarizes double-leg and single-leg jump test reference values for athletes who play common pivoting sports, including soccer and basketball. J Orthop Sports Phys Ther 2024;54(6):1-14. Epub 20 March 2024. doi:10.2519/jospt.2024.12374.

Impact of Surgical Timing on Functional Outcomes after Anterior Cruciate Ligament Reconstruction

Objectives: Although acute anterior cruciate ligament reconstruction (ACLR) is often avoided because of postoperative joint stiffness, delayed ACLR can lead to a longer recovery time and can have a negative impact on physical function due to detraining. This study aimed to determine the effects of acute ACLR on postoperative outcomes, including muscle strength, performance, and return to sports. Methods: A total of 110 patients who underwent anatomical ACLR using hamstring autografts were included in this study and were divided into three groups: acute (ACLR performed within 2 weeks after ACL injury), 2-6 weeks (ACLR performed between 2 and 6 weeks after injury), and 6-12 weeks (ACLR performed between 6 and 12 weeks after injury). Several parameters were evaluated, including range of motion, knee joint stability, isokinetic knee strength, performance, and return to sports. Results: No significant differences were found in the range of motion or knee joint stability between the groups. The acute group exhibited significantly greater quadriceps strength at 3 months postoperatively than the other groups (p < 0.05). The single-leg hop test showed that 66.7%, 38.7%, and 33.3% of the patients in the acute, 2-6 weeks, and 6-12 weeks groups, respectively, recovered to an LSI of 90% or greater (p = 0.09, Cramer's V = 0.27). All patients in the acute group were able to return to sports (p = 0.14; Cramer's V = 0.28). Conclusions: Acute ACLR is advantageous for the early recovery of strength and performance without adverse events. Acute ACLR may shorten the time spent away from sports activities.

A new neural network model that detects graft ruptures and contralateral anterior cruciate ligament injuries

PURPOSE

The purpose of this study was to develop a neural network model for predicting second anterior cruciate ligament (ACL) injury risk following ACL reconstruction using patient features from medical records.

METHODS

Of 486 consecutive patients who underwent primary unilateral ACL reconstruction, 386 patients (198 women, 188 men) with a mean age of 25.1 ± 11.6 years were included in this study. Fifty-eight features, including demographic data, surgical, preoperative and postoperative data, were retrospectively collected from medical records, and features with an incidence of less than 5% were excluded. Finally, 14 features were used for the analysis. The multilayer perceptron was composed of four hidden layers with a rectified linear unit as activation and was trained to maximise the area under the receiver-operating characteristic curve (auROC). Subsequently, validation was carried out through a rigorous threefold cross-validation process. To ascertain the most efficacious combination of features with the highest auROC, a single feature with the least impact on auROC maximisation was systematically eliminated from the comprehensive variable set, ultimately resulting in the retention of a mere two variables.

RESULTS

The median follow-up period was 50.5 (24-142) months. Fifty-seven knees had a second ACL injury, with a graft rupture rate of 7.7% and a contralateral injury rate of 6.9%. The maximum auROC for predicting graft rupture was 0.81 with two features: young age and hamstring graft. Meanwhile, the maximum auROC for predicting contralateral ACL injury was 0.74 with seven features, including young age, presence of medial meniscus tear, small body mass index, hamstring graft, female sex and medial meniscus repair or treatment.

CONCLUSION

A neural network model with patient features from medical records detected graft ruptures and contralateral ACL injuries with acceptable accuracy. This model can serve as a new, useful tool in clinical practice to inform decisions about ACL reconstruction and retuning to sports postoperatively.

LEVEL OF EVIDENCE

Level IV.

Association Between Psychological Readiness to Return to Sports at 3 Months Postoperatively and Risk of Second ACL Injury

Background

Psychological readiness to return to sports (RTS) has been associated with second anterior cruciate ligament (ACL) injury. However, this relationship is controversial because covariates such as anatomic and knee function characteristics have not been adequately considered.

Purpose/Hypothesis

To investigate whether psychological readiness in the early postoperative period can predict the occurrence of a second ACL injury within 24 months after primary ACL reconstruction (ACLR) using propensity score analysis. It was hypothesized that patients with high ACL-RSI after injury (ACL-RSI) scores at 3 months postoperatively would have a second ACL injury within the projected postoperative period.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 169 patients who underwent primary ACLR using hamstring tendon autografts between November 2017 and July 2021 and also underwent knee functional assessments at 3 months postoperatively. The ACL-RSI scale was used to assess psychological readiness for RTS. A second ACL injury was defined if ipsilateral or contralateral ACL injury was confirmed by examination within 24 months postoperatively. Based on a previous study showing that 65 was the highest cutoff value for the ACL-RSI score for RTS, we classified patients into 2 groups: those with high ACL-RSI scores (≥65; group H) and those with low ACL-RSI scores (<65; group L). We generated 1-to-1 matched pairs using propensity score analysis and used log-rank testing to compare the rate of second ACL injury between the 2 groups.

Results

More patients returned to any sports activities within 12 months in group H than in group L (90% vs 73%; P = .03). A second ACL injury within 24 months postoperatively was identified in 7% of patients (13/169). The rate of second ACL injury was significantly higher in group H than in group L (17.6% vs 3.4%; P = .001). In 43 matched pairs extracted using propensity scoring, the rate of second ACL injury was also higher in group H than in group L (18.6% vs 4.7%; P = .04).

Conclusion

Patients with a higher ACL-RSI score at 3 months exhibited a significantly higher incidence of second ACL injury within 24 months after primary ACLR.

Better Safe Than Sorry? A Systematic Review with Meta-analysis on Time to Return to Sport After ACL Reconstruction as a Risk Factor for Second ACL Injury

OBJECTIVE: To compare the time to return to sport (RTS) between patients who did and did not suffer a second anterior cruciate ligament (ACL) injury after ACL reconstruction. DESIGN: Etiology systematic review with meta-analysis. LITERATURE SEARCH: Cochrane Library, Embase, Medline, AMED, and PEDro databases were searched in August 2021 and again in November 2022. STUDY SELECTION CRITERIA: Clinical studies reporting time to RTS after ACL reconstruction and second ACL injury were eligible. DATA SYNTHESIS: We pooled continuous data (time [months] and proportions [%]), with random-effects meta-analyses. Pooled estimates were summarized in forest plots. A qualitative data synthesis was also performed. RESULTS: Twenty-one studies were included in the meta-analysis and 33 in the qualitative synthesis. Pooled incidence of second ACL injury was 16.9% (95% confidence interval [CI]: 12.8, 21.6). Patients who suffered a second ACL injury returned to sport significantly earlier (25 days; 95% CI: 9.5, 40.4) than those who did not suffer another injury. There was no difference in time to RTS for professional athletes who suffered a second ACL injury and those who did not. The certainty of evidence was very low. CONCLUSION: There was very low-certainty evidence that patients who suffered a second ACL injury had returned to sport 25 days earlier than patients who did not have another injury. For professional athletes, there was no difference in time to RTS between athletes who suffered a second ACL injury and athletes who did not. J Orthop Sports Phys Ther 2024;54(3):1-15. Epub 30 November 2023. doi:10.2519/jospt.2023.11977.

Risk Factors for Ipsilateral Versus Contralateral Reinjury After ACL Reconstruction in Athletes: A Systematic Review and Meta-analysis

Background

Anterior cruciate ligament (ACL) reinjury after ACL reconstruction (ACLR) can occur on the ipsilateral or contralateral side. Limited evidence exists regarding the difference between the incidence of reinjury to either knee, which is important in developing interventions to prevent ACL reinjury.

Purpose

To compare the reinjury rate of the ACL on the ipsilateral side versus the contralateral side in athletes after ACLR and investigate the risk factors that may cause different reinjury rates between the sides.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic review was performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies that involved ACL reinjury in athletes after ACLR were reviewed. Considering several risk factors, including age and sex, a comparison of ACL reinjury incidence on the ipsilateral and contralateral sides was performed using a meta-analysis.

Results

Of the 17 selected studies, 3 were found to be at high risk of bias, and thus, 14 (n = 3424 participants) studies were included in the meta-analysis. In this athletic population, the contralateral ACL had a significantly higher rupture rate than the ipsilateral graft (risk ratio [RR], 1.41; P < .0001). Female athletes were found to have a greater risk of ACL reinjury on the contralateral versus the ipsilateral side (RR, 1.65; P = .0005), but different results were found in male athletes. (RR, 0.81; P = .21). There was no statistical difference in the incidence rate of ACL reinjury to either side in adolescent athletes (RR, 1.15; P = .28).

Conclusion

The contralateral ACL was more vulnerable to reinjury than the ipsilateral side in athletes after ACLR. Female athletes were more likely to reinjure their contralateral native ACL, while the same trend was not found in their male counterparts. The reinjury rate was comparable in both knees in adolescent athletes.

It is time to target psychological readiness (or lack of readiness) in return to sports after Anterior Cruciate Ligament tears

Functional recovery has for long been the focus of rehabilitation after an Anterior Cruciate Ligament (ACL) injury. It is now increasingly recognized that more attention should be given to patients` mental recovery, their psychological readiness for returning to sport, after such an injury. Within this relatively new field of science, clinicians need clarity on when and how psychological factors should be monitored and how inexpedient psychological responses may be addressed during rehabilitation. In this Expert Opinion suggestions on how targeting psychological readiness may improve rehabilitation and return-to-sport evaluations are made based on current evidence-and issues in need of further clarification are addressed.

Feasibility of return to sports assessment 6 months after patellar instability surgery

BACKGROUND

The evidence regarding the usefulness of assessment tools to support decisions of return-to-sport after surgery for patellar instability is scarce. The purpose of this study was therefore to explore the feasibility of functional tests assessing readiness for return-to-sport six months after patellar stabilizing surgery. However, there is little evidence on what a functional assessment should include to support these decisions following surgery for patellar instability. Therefore the purpose of this study was to explore the feasibility of functional tests assessing readiness for return-to-sport six months after patellar stabilizing surgery.

METHODS

In this cross-sectional study a prospective cohort of 78 patients were subjected to a range of return-to-sport readiness tests at six months after surgery for patellar instability with an "a la carte" approach. Lower Quarter Y-Balance Test (YBT-LQ), single-legged hop tests and isokinetic strength tests were performed. In addition, self-reported function was measured with the Banff Patellofemoral Instability Instrument 2.0 (BPII) and Norwich Patellar Instability score (NPI). Return-to-sport clearance criteria were defined as: ≤4 cm YBT-LQ anterior reach difference between legs, leg-symmetry-index (LSI) ≥ 95% in the YBT-LQ composite score, mean sum score LSI ≥ 85% of all single-leg hop tests and LSI ≥ 90% in isokinetic quadriceps strength.

RESULTS

Sixty-four patients (82%) were able to complete all functional tests, while only eleven (14%) patients were deemed ready for return-to-sport, passing all return-to-sport clearance criteria. Patients with bilateral problems demonstrated worse performance in the contralateral leg, which resulted in higher LSI scores compared to individuals with unilateral instability. A supplementary finding was that the extent of surgery (MPFL-R only versus combined surgery) did not predict and mainly did not affect self-reported function or functional performance at the follow-up.

CONCLUSION

The functional assessment used in the current study seems feasible to conduct at six months after patellar stabilizing surgery. However, current suggested clearance standards and the use of leg-symmetry-index seems inappropriate for patients with patellar instability. Therefore, further exploration of appropriate tests and return-to-sport clearance criteria is justified.

TRIAL REGISTRATION

clinicaltrial.gov, NCT05119088. Registered 12.11.2021 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05119088 .

No Effect of Return to Sport Test Batteries with and without Psychological PROs on the Risk of a Second ACL Injury: A Critical Assessment of Four Different Test Batteries

Background

Patients report psychological barriers as important when returning to sport, however, psychological outcome measures are seldom included in return to sport (RTS) assessment. There is a need for clinical trials to integrate psychological patient-reported outcomes (PROs) in return to sport batteries assessing patients treated with ACL reconstruction.

Objective

The aim of this study was to determine the association between passing clinical tests of muscle function and psychological PROs and sustaining a second ACL injury in patients who RTS after primary ACL reconstruction.

Design

Retrospective Cohort study.

Methods

Patients' sex, age, height and weight, and the results of strength and hop tests, as well as answers to PRO's (including Tegner activity scale, the ACL Return to Sport after Injury scale (ACL-RSI) as well as the Quality of Life (QoL) subscale of the Knee injury and Osteoarthritis Outcome Score [KOOS]), were extracted from a rehabilitation-specific registry. Four different test batteries comprising muscle function tests and PROs were created to assess whether patients were ready to RTS. Passing each of the test batteries (yes/no) was used as an independent variable. A multivariable Cox proportional hazard model analysis was performed, with sustaining a second ACL injury (either ipsi- or contralateral; yes/no) within two years of RTS as the dependent variable.

Results

A total of 419 patients (male, n=214; 51%) were included, of which 51 (12.2%) suffered a second ACL injury within the first two years after RTS. There were no differences in passing rates in the different RTS test batteries comprising muscle function tests and PROs for patients who suffered a second ACL injury compared to patients who did not.

Conclusion

No association between passing the RTS clinical tests batteries comprising muscle function and psychological PROs used, and the risk of a second ACL injury could be found.

Level of Evidence

3©The Author(s).

Anterior Cruciate Ligament Rehabilitation for the 10- to 18-Year-Old Adolescent Athlete: Practice Guidelines Based on International Delphi Consensus

Background

There are 2 treatment options for adolescent athletes with anterior cruciate ligament (ACL) injuries-rehabilitation alone (nonsurgical treatment) or ACL reconstruction plus rehabilitation. However, there is no clear consensus on how to include strength and neuromuscular training during each phase of rehabilitation.

Purpose

To develop a practical consensus for adolescent ACL rehabilitation to help provide care to this age group using an international Delphi panel.

Study Design

Consensus statement.

Methods

A 3-round online international Delphi consensus study was conducted. A mix of open and closed literature-based statements were formulated and sent out to an international panel of 20 ACL rehabilitation experts. Statements were divided into 3 domains as follows: (1) nonsurgical rehabilitation; (2) prehabilitation; and (3) postoperative rehabilitation. Consensus was defined as 70% agreement between panel members.

Results

Panel members agreed that rehabilitation should consist of 3 criterion-based phases, with continued injury prevention serving as a fourth phase. They also reached a consensus on rehabilitation being different for 10- to 16-year-olds compared with 17- and 18-year-olds, with a need to distinguish between prepubertal (Tanner stage 1) and mid- to postpubertal (Tanner stages 2-5) athletes. The panel members reached a consensus on the following topics: educational topics during rehabilitation; psychological interventions during rehabilitation; additional consultation of the orthopaedic surgeon; duration of postoperative rehabilitation; exercises during phase 1 of nonsurgical and postoperative rehabilitation; criteria for progression from phase 1 to phase 2; resistance training during phase 2; jumping exercises during phase 2; criteria for progression from phase 2 to phase 3; and criteria for return to sports (RTS). The most notable differences in recommendations for prepubertal compared with mid- to postpubertal athletes were described for resistance training and RTS criteria.

Conclusion

Together with available evidence, this international Delphi statement provides a framework based on expert consensus and describes a practice guideline for adolescent ACL rehabilitation, which can be used in day-to-day practice. This is an important step toward reducing practice inconsistencies, improving the quality of rehabilitation after adolescent ACL injuries, and closing the evidence-practice gap while waiting for further studies to provide clarity.

Let's talk about sex (and gender) after ACL injury: a systematic review and meta-analysis of self-reported activity and knee-related outcomes

OBJECTIVE

Investigate sex/gender differences in self-reported activity and knee-related outcomes after anterior cruciate ligament (ACL) injury.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Seven databases were searched in December 2021.

ELIGIBILITY CRITERIA

Observational or interventional studies with self-reported activity (including return to sport) or knee-related outcomes after ACL injury.

RESULTS

We included 242 studies (n=123 687, 43% females/women/girls, mean age 26 years at surgery). One hundred and six studies contributed to 1 of 35 meta-analyses (n=59 552). After ACL injury/reconstruction, very low-certainty evidence suggests females/women/girls had inferior self-reported activity (ie, return to sport, Tegner Activity Score, Marx Activity Scale) compared with males/men/boys on most (88%, 7/8) meta-analyses. Females/women/girls had 23%-25% reduced odds of returning to sport within 1-year post-ACL injury/reconstruction (12 studies, OR 0.76 95% CI 0.63 to 0.92), 1-5 years (45 studies, OR 0.75 95% CI 0.69 to 0.82) and 5-10 years (9 studies, OR 0.77 95% CI 0.57 to 1.04). Age-stratified analysis (<19 years) suggests female athletes/girls had 32% reduced odds of returning to sport compared with male athletes/boys (OR 0.68, 95% CI 0.41 to 1.13, I² 0.0%). Very low-certainty evidence suggests females/women/girls experienced inferior knee-related outcomes (eg, function, quality of life) on many (70%, 19/27) meta-analyses: standardised mean difference ranging from -0.02 (Knee injury and Osteoarthritis Outcome Score, KOOS-activities of daily living, 9 studies, 95% CI -0.05 to 0.02) to -0.31 (KOOS-sport and recreation, 7 studies, 95% CI -0.36 to -0.26).

CONCLUSIONS

Very low-certainty evidence suggests inferior self-reported activity and knee-related outcomes for females/women/girls compared with males/men/boys after an ACL injury. Future studies should explore factors and design targeted interventions to improve outcomes for females/women/girls.

PROSPERO REGISTRATION NUMBER

CRD42021205998.

Evidence Review for Preventing Osteoarthritis After an Anterior Cruciate Ligament Injury: An Osteoarthritis Action Alliance Consensus Statement

CONTEXT

The Osteoarthritis Action Alliance formed a secondary prevention task group to develop a consensus on secondary prevention recommendations to reduce the risk of osteoarthritis after a knee injury.

OBJECTIVE

Our goal was to provide clinicians with secondary prevention recommendations that are intended to reduce the risk of osteoarthritis after a person has sustained an anterior cruciate ligament injury. Specifically, this manuscript describes our methods, literature reviews, and dissenting opinions to elaborate on the rationale for our recommendations and to identify critical gaps.

DESIGN

Consensus process.

SETTING

Virtual video conference calls and online voting.

PATIENTS OR OTHER PARTICIPANTS

The Secondary Prevention Task Group consisted of 29 members from various clinical backgrounds.

MAIN OUTCOME MEASURE(S)

The group initially convened online in August 2020 to discuss the target population, goals, and key topics. After a second call, the task group divided into 9 subgroups to draft the recommendations and supportive text for crucial content areas. Twenty-one members completed 2 rounds of voting and revising the recommendations and supportive text between February and April 2021. A virtual meeting was held to review the wording of the recommendations and obtain final votes. We defined consensus as >80% of voting members supporting a proposed recommendation.

RESULTS

The group achieved consensus on 15 of 16 recommendations. The recommendations address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models.

CONCLUSIONS

This consensus statement reflects information synthesized from an interdisciplinary group of experts based on the best available evidence from the literature or personal experience. We hope this document raises awareness among clinicians and researchers to take steps to mitigate the risk of osteoarthritis after an anterior cruciate ligament injury.

Return to Sports: A Risky Business? A Systematic Review with Meta-Analysis of Risk Factors for Graft Rupture Following ACL Reconstruction

BACKGROUND

The risk of sustaining a graft rupture after anterior cruciate ligament reconstruction (ACLR) is high. Contributing risk factors are, however, still not clearly identified.

OBJECTIVE

The aim of this systematic review was to identify and quantify risk factors for graft rupture after ACLR.

METHODS

A systematic review with meta-analysis (PROSPERO CRD42020140129) based on PRISMA guidelines was performed. MEDLINE, CINAHL and EMBASE were searched from inception to September 2021. Prospective and retrospective studies addressing risk factors for graft rupture after ACLR in males/females of all ages were considered. Meta-analyses using a random effect model (effect measure: odds ratio [OR] with 95% confidence interval [CI]) were performed. The GRADE tool was used to assess evidence quality.

RESULTS

Following full-text screening of 310 relevant papers, 117 were eventually included, incorporating up to 133,000 individuals in each meta-analysis. Higher Tegner activity level (≥ 7 vs < 7) at primary injury (OR 3.91, 95% CI 1.69-9.04), increased tibial slope (degrees) (OR 2.21, 95% CI 1.26-3.86), lower psychological readiness to return to sport (RTS) (OR 2.18, 95% CI 1.32-3.61), early surgery (< 12 vs ≥ 12 months) (OR 1.87, 95% CI 1.58-2.22), RTS (pre-injury level) (OR 1.87, 95% CI 1.21-2.91) and family history of ACL injury (OR 1.76, 95% CI 1.34-2.31) were all associated with increased odds of graft rupture. Higher age (OR 0.47, 95% CI 0.39-0.59), female sex (OR 0.88, 95% CI 0.79-0.98), fewer self-reported knee symptoms pre-reconstruction (OR 0.81, 95% CI 0.69-0.95) and concomitant cartilage injuries (OR 0.70, 95% CI 0.62-0.79) instead decreased the odds. Meta-analysis revealed no association between body mass index, smoking, joint laxity, RTS time, knee kinematics, muscle strength or hop performance and graft rupture.

CONCLUSION

Conspicuous risk factors for graft rupture were mainly sports and hereditary related. Few studies investigated function-related modifiable factors or included sports exposure data.

'I was young, I wanted to return to sport, and re-ruptured my ACL' - young active female patients' voices on the experience of sustaining an ACL re-rupture, a qualitative study

Background

Despite anterior cruciate ligament (ACL) re-ruptures being common, research on patient experiences after knee trauma has primarily focused on the time after primary ACL reconstruction. Integrating qualitative research and patient experiences can facilitate researchers and clinicians in understanding the burden of an ACL re-rupture. The aim of the study was to explore the experiences of an ACL re-rupture journey in young active females aiming to return to knee-strenuous sports after primary ACL reconstruction.

Method

Fifteen young (19[range 16–23] years old) active females who suffered an ACL re-rupture were interviewed with semi-structured interviews. Qualitative content analysis using deductive approach based on Wiese-Bjornstal’s ‘integrated model of response to sport injury’ was used.

Results

The results are presented in two timelines 1) from first ACL injury to ACL re-rupture, and 2) from ACL re-rupture to present day, and further stratified according to the domains of the ‘integrated model of psychological response to injury’. Results in the first timeline are summarised into seven categories: Finding hope for the journey; Accepting my ACL injury; I succeeded; What matters now? Who am I?; Where will this end? What is going to happen? In the second timeline, eight categories were identified: Fighting spirit; A helping hand; Working hard; I am a new me; I am destroyed; Loneliness; Painful changes; and, I could have made it to the pro´s.

Conclusion

Young active females who suffered an ACL re-rupture did not express any positive experience following their first ACL injury, however, in contrast, expressed positive experiences and personal growth after going through the ACL re-rupture journey, characterized by a lot of struggling, and ultimately led to the experience of becoming a new, stronger person.

Disagreement in Pass Rates Between Strength and Performance Tests in Patients Recovering From Anterior Cruciate Ligament Reconstruction

BACKGROUND

Performance on strength and functional tests is often used to guide postoperative rehabilitation progress and return to activity decisions after anterior cruciate ligament reconstruction (ACLR). Clinicians may have difficulty in determining which criteria to follow if there is disagreement in performance outcomes among the tests.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare pass rates between strength tests and single-leg hop (SLHOP) tests among men and women and between patients with lower and higher preinjury activity levels recovering from ACLR. We hypothesized that pass rates would be nonuniformly distributed among test types, sex, and activity level and that more participants would pass hop tests than strength tests.

DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 299 participants (146 men; 153 women)-at a mean of 6.8 ± 1.4 months after primary, unilateral, and uncomplicated ACLR (mean age, 23 ± 9.7 years; mean height, 172 ± 10.5 cm; mean mass, 75.8 ± 18.4 kg)-completed testing. Quadri.tif strength was evaluated using peak torque during isokinetic knee extension at 90 deg/s and 180 deg/s. Jump distance during the SLHOP and triple hop tests was measured (in cm). Strength and hop test measures were evaluated based on the limb symmetry index ((LSI) = (ACLR / contralateral side) × 100). We operationally defined "pass" as >90% on the LSI.

RESULTS

Pass rates were nonuniformly distributed between isokinetic knee extension at 90 deg/s and the SLHOP test (χ² = 18.64; P < .001). Disagreements between isokinetic testing at 90 deg/s and the SLHOP test occurred in 36.5% (109/299) of the participants. Among those who failed strength testing and passed hop testing, a greater portion reported higher activity levels before their injury (χ² = 6.90; P = .01); however, there was no difference in pass rates between men and women. Similar patterns of disagreement were observed between all strength test and hop test outcomes.

CONCLUSION

ACLR patients with higher activity levels may be more likely to pass hop testing despite failing quadri.tif strength testing. This may be an indicator of movement compensations to achieve jump symmetry in the presence of quadri.tif weakness.

A Minority of Athletes Pass Symmetry Criteria in a Series of Hop and Strength Tests Irrespective of Having an ACL Reconstructed Knee or Being Noninjured

BACKGROUND

Between-leg symmetry in 1-leg hop and knee strength performances is considered important after anterior cruciate ligament reconstruction (ACLR) to facilitate a safer return to sport. While few athletes with ACLR demonstrate symmetry in test batteries, reference data for noninjured athletes are lacking, thus questioning how ACLR-specific poor symmetry is.

HYPOTHESIS

Athletes with ACLR (hamstring autograft) show lower symmetry and have a lower proportion of symmetric individuals than noninjured athletes for knee flexion strength but not for hop for distance, vertical hop, and knee extension strength.

STUDY DESIGN

Cross-sectional.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 47 athletes with ACLR (median 13.0 months post-ACLR) who had returned to their sport, and 46 noninjured athletes participated. Symmetry was calculated between the worse and better legs for each test and combinations of them using the limb symmetry index (LSI_WORSE-BETTER, ranging from 0% to 100%). The 2 groups were compared for these values and the proportions of individuals classified as symmetric (LSI_WORSE-BETTER ≥90%) using independent t-tests and Fisher's exact tests, respectively.

RESULTS

Athletes with ACLR were less symmetric than noninjured athletes for knee flexion strength with a lower LSI_WORSE-BETTER (83% vs 91%, P < 0.01) and a lower proportion of symmetric individuals (39% vs 63%, P = 0.04). No differences between groups were revealed for the hop tests, knee extension strength, or combinations of tests (P > 0.05). Only 17% of the athletes with ACLR and 24% of the noninjured athletes demonstrated symmetric performances for all 4 tests.

CONCLUSION

Athletes with ACLR (hamstring autograft) showed poorer symmetry in knee flexion strength than noninjured athletes, although both groups had few individuals who passed the test battery's symmetry criteria.

CLINICAL RELEVANCE

Symmetry is uncommon among athletes irrespective of ACLR and should be considered regarding expected rehabilitation outcomes and return-to-sport decisions post-ACLR.

'Such a massive part of rehab is between the ears'; barriers to and facilitators of anterior cruciate ligament reconstruction rehabilitation: a qualitative focus group analysis

Background

Current evidence demonstrates that few patients complete anterior cruciate ligament reconstruction rehabilitation according to evidence-based guidelines. It is important to investigate the viewpoints of our patients to identify patient-reported barriers and facilitators of anterior cruciate ligament reconstruction rehabilitation. Qualitative analysis can provide insight into potential methods for improving the delivery of rehabilitation services.

Methods

In this qualitative study, utilising a social constructionism orientation, viewed through the social phenomenological lens, three focus groups were conducted with individuals 1–20 years post anterior cruciate ligament reconstruction (n = 20, 9 males, 11 females, mean 6.5 years post-surgery, 19–51 years old). Utilising a semi-structured interview guide, participants were asked about their experiences during anterior cruciate ligament reconstruction rehabilitation. Focus groups were recorded, transcribed, and coded using an inductive semantic thematic analysis methodology.

Results

Five organising themes were identified (consisting of 19 sub-themes) to provide a framework to present the data: psychological, physiological, rehabilitation service, rehabilitation characteristics, and interaction with others. Each theme details aspects of rehabilitation, such as exercise delivery, informational support, frequency, and duration of care, kinesiophobia, weight management and interactions with teams and coaches, which present barriers or facilitators for patients to adhere to and participate in rehabilitation. Example quotes are provided for each theme to provide context and the patient’s voice.

Conclusions

This qualitative investigation identified key aspects of a patient's rehabilitation in which they encounter a variety of barriers and facilitators of ACL reconstruction rehabilitation. These aspects, such as the rehabilitation characteristics, service delivery, psychological and physiological factors, and interactions with others, were consistently identified by this cohort as factors which affected their rehabilitation. The themes may provide targets for clinicians to improve rehabilitation and deliver patient-centred care. However, the themes must be evaluated in future trials to assess whether interventions to remove barriers or enhance facilitators improves subsequent outcomes such as return to sport and re-injury rates.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-022-00499-x.

Epidemiological Comparison of ACL Injuries on Different Playing Surfaces in High School Football and Soccer

Background:

Anterior cruciate ligament (ACL) injuries are among the most common serious injuries to athletes in the United States. Among high school sports, the highest rates of ACL injury occur in soccer and football.

Purpose:

To compare ACL injuries on artificial turf and natural grass using a nationally representative sample of high school athletes participating in football and boys’ and girls’ soccer.

Study Design:

Descriptive epidemiology study.

Methods:

ACL injuries among high school athletes participating in football and soccer were obtained from the High School Reporting Information Online surveillance system during the 2007-08 through 2018-19 school years. National estimates and injury proportion ratios (IPRs) with 95% CIs were calculated for ACL injuries that occurred on artificial turf versus natural grass.

Results:

A total of 1039 ACL injuries were reported, which represented an estimated 389,320 (95% CI, 358,010-420,630) injuries nationally. There were 74,620 estimated football-related ACL injuries on artificial turf and 122,654 on natural grass. Likewise, 71,877 of the estimated soccer-related ACL injuries occurred on artificial turf and 104,028 on natural grass. A contact-injury mechanism accounted for 50.2% of football-related ACL injuries on artificial turf and 60.8% on natural grass. For soccer-related ACL injuries, a noncontact mechanism predominated on artificial turf (61.5%) and natural grass (66.4%). Among all injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both football (IPR, 1.23 [95% CI, 1.03-1.47]) and girls’ soccer (IPR, 1.53 [95% CI, 1.08-2.16]); however, no significant association was found in boys’ soccer (IPR, 1.65 [95% CI, 0.99-2.75]). Among lower extremity injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both boys’ soccer (IPR, 1.72 [95% CI, 1.03-2.85]) and girls’ soccer (IPR, 1.61 [95% CI, 1.14-2.26]); however, the association was not significant in football (IPR, 1.17 [95% CI, 0.98-1.39]).

Conclusion:

ACL injuries were more likely to occur (ie, had larger IPRs) on artificial turf than natural grass; however, this relationship was not statistically significant for all sports.

Greater Psychological Readiness to Return to Sport, as Well as Greater Present and Future Knee-Related Self-Efficacy, Can Increase the Risk for an Anterior Cruciate Ligament Re-Rupture: A Matched Cohort Study

PURPOSE

To determine the psychological characteristics and strength outcomes of patients who sustained an early anterior cruciate ligament (ACL) re-rupture after their primary ACL reconstruction and cross-sectionally compare them with a matched cohort of patients who did not sustain a reinjury during the first 2 years after primary ACL reconstruction.

METHODS

In this matched cohort study, data for quadriceps and hamstring strength and 3 hop tests and answers to standardized patient-reported outcomes (the Anterior Cruciate Ligament Return to Sport after Injury scale and a short version of the Knee Self-Efficacy Scale) were extracted from a rehabilitation outcome registry. Data for patients suffering a re-rupture were extracted, and patients were matched in terms of sex, age, and activity level with patients not suffering an ACL re-rupture within 2 years of primary reconstruction. The groups were compared 10 weeks and 4, 8, and 12 months after the primary reconstruction.

RESULTS

A total of 36 patients suffering an ACL re-rupture were matched with 108 patients not suffering a re-rupture after ACL reconstruction. Patients who suffered an ACL re-rupture had greater psychological readiness, that is, greater confidence in performance, lesser negative emotions, and lesser risk appraisal, to return to sport (RTS) at 8 months (81.2 vs 67.9 [95% Δconfidence interval {CI} 2.7-23.8) P = .014) and at 12 months (95.2 vs 67.1, (95% ΔCI 14.3-41.8) P ≤ .001), and greater knee-related self-efficacy at 8 months (8.6 vs 8.0 [95% ΔCI 0.1-1.2], P = .021) and 12 months (9.4 vs 8.1, [95% ΔCI 0.3-2.2] P = .012) after primary ACL reconstruction, compared with the matched group.

CONCLUSIONS

A stronger psychological profile, defined by a greater psychological readiness to RTS and knee-related self-efficacy, may be associated with an ACL re-rupture within 2 years of the primary reconstruction.

LEVEL OF EVIDENCE

Matched cohort study, level III.

Quadriceps and Hamstrings Strength Reference Values for Athletes With and Without Anterior Cruciate Ligament Reconstruction Who Play Popular Pivoting Sports, Including Soccer, Basketball, and Handball: A Scoping Review

OBJECTIVE

To synthesize and present reference values for quadriceps and hamstrings strength tests in healthy athletes who play pivoting sports and in athletes with anterior cruciate ligament reconstruction (ACLR) who play pivoting sports.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched PubMed, the Cochrane Library, MEDLINE, Embase, and Web of Science up to January 26, 2021.

STUDY SELECTION CRITERIA

We included reference values in 2 different categories: (1) quadriceps and hamstrings strength test outcomes in healthy pivoting-sport athletes, and (2) quadriceps and hamstrings strength test outcomes in pivoting-sport athletes with ACLR at a specific time point during rehabilitation.

DATA SYNTHESIS

We performed a qualitative synthesis for reference values from isokinetic (at 60°/s, 180°/s, and 300°/s) and isometric quadriceps and hamstrings strength tests. We summarized the data for type of sport, sex, sport participation level, and age group.

RESULTS

Of the 42 included studies, 26 reported reference values from healthy soccer players, 4 from healthy basketball players, 4 from healthy handball players, and 11 from other healthy pivoting-sport athletes. The limb symmetry index dominant/nondominant limb (LSI-D/ND) ranged from 98% to 114% for healthy athletes. Six studies reported reference values in pivoting-sport athletes with ACLR at a specific time point during rehabilitation. After 7 months, strength values for athletes with ACLR were comparable to those of healthy pivoting-sport athletes.

CONCLUSION

This scoping review summarizes quadriceps and hamstrings strength reference values for athletes who play the most common pivoting sports, including soccer, basketball, and handball. J Orthop Sports Phys Ther 2022;52(3):142-155. Epub 31 Dec 2021. doi:10.2519/jospt.2022.10693.

Suture tape reinforcement of hamstring tendon graft reduces postoperative knee laxity after primary ACL reconstruction

Purpose

To evaluate and compare subjective and objective knee outcomes following hamstring tendon (HT) and quadriceps tendon (QT) anterior cruciate ligament reconstruction (ACLR) with or without suture tape (ST) reinforcement. It was hypothesized that the addition of an intra-articular synthetic augmentation with a ST would reduce postoperative knee laxity and graft ruptures after ACLR.

Methods

A 1:1 matched-cohort comparison of patients who underwent HT and QT autograft ACLR with or without ST reinforcement was performed. Patients with ST reinforcement were consecutively assigned to the study groups until a number of 20 in each group was achieved. Medical records were reviewed for demographic characteristics and additional injuries. Laxity measurements with KT-1000, strength measurements and physical examination findings were collected both preoperatively and at 6 months and patient reported outcome (PRO) scores were collected both preoperatively and at 12 months, and comparison was made HT vs HT + ST and QT vs QT + ST. Reoperations and re-ruptures were recorded during the 24-month follow-up period.

Results

Overall, 80 patients who underwent ACLR were included. Patients with HT + ST had significant less laxity postoperatively compared to HT at 6 months, 1.9 vs 0.8 mm, p < 0.05. No differences were found between the QT and QT + ST group. At 6 weeks patients treated with ST, both QT and HT, had a significant deficit in flexion compared to those without ST. However, this resolved at 6 months. There were no significant differences between HT + ST vs HT, or QT + ST vs QT, regarding postoperative PROs or strength measurements. Furthermore, the incidence of subsequent surgery and graft rupture was not significantly different between the groups.

Conclusion

ACLR with HT + ST reduces laxity at 6 months compared to ACLR without ST, a difference not seen when ACLR was performed using QT with or without ST. No other differences were seen between the two techniques comparing subjective and objective findings.

Level of evidence

Level III.

Exercise Descriptors That Determine Muscle Strength Gains Are Missing From Reported Anterior Cruciate Ligament Reconstruction Rehabilitation Programs: A Scoping Review of 117 Exercises in 41 Studies

OBJECTIVE

To (1) describe which strength training exercise descriptors are reported in anterior cruciate ligament reconstruction (ACLR) rehabilitation research, and (2) compare the current standards of reporting ACLR strength training exercise descriptors to international best-practice strength training guidelines.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched the MEDLINE, PsycINFO, CINAHL, SPORTDiscus, Academic Search, ERIC, Health Source: Nursing, Health Source: Consumer, MasterFILE, and Africa-Wide Information databases.

STUDY SELECTION CRITERIA

We included level I to IV studies of ACLR rehabilitation programs with 1 or more reported strength training exercise descriptors. We used a predefined list of 19 exercise descriptors, based on the American College of Sports Medicine (ACSM) exercise recommendations, the Consensus on Exercise Reporting Template (CERT), and the Toigo and Boutellier exercise descriptor framework.

DATA SYNTHESIS

Completeness and the standard of reporting exercise descriptors in ACLR rehabilitation programs were assessed by means of international best-practice strength training standards.

RESULTS

We extracted data on 117 exercises from 41 studies. A median of 7 of the 19 possible exercise descriptors were reported (range, 3-16). Reporting of specific exercise descriptors varied across studies, from 95% (name of the strength training exercise) to 5% (exercise aim, exercise order). On average, 46%, 35%, and 43% of the exercise descriptors included in the ACSM, CERT, and Toigo and Boutellier guidelines were reported, respectively.

CONCLUSION

Key exercise descriptors for muscle strength gains are not reported in studies on ACLR rehabilitation. Only the exercise name, number of exercises, frequency, and experimental period were reported in most of the studies. J Orthop Sports Phys Ther 2022;52(2):100-112. Epub 16 Nov 2021. doi:10.2519/jospt.2022.10651.

Meeting movement quantity or quality return to sport criteria is associated with reduced second ACL injury rate

The purposes of this prospective cohort study were (1) to assess if second anterior cruciate ligament (ACL) injury rate 2 years after ACL reconstruction (ACLR) in those who returned to pivoting sport was associated with meeting (a) quantitative return to sport (RTS) criteria, (b) qualitative RTS criteria, and (c) combined quantitative and qualitative RTS criteria, and (2) to determine why athletes did not return to their preinjury (level of) sport. Athletes after ACLR performed RTS tests immediately before RTS: seven movement quantity (strength and hop test battery) and two movement quality (countermovement jump with LESS score and hop-and-hold test) tests. A 2-year postoperative questionnaire asked for RTS, reasons for not returning to the same (level of) sport and second ACL injuries. One hundred and forty-four athletes (82%) completed the questionnaire and 97 of them returned to a pivoting sport. Seven of these athletes had a second ACL injury. Meeting the hop test battery RTS criterion (absolute risk reduction 11%; p = .047) and hop-and-hold test RTS criterion (absolute risk reduction 15%; p = .031) were both significantly associated with a reduced second ACL injury rate. Meeting combined RTS criteria were not significantly associated with second ACL injury rate. Therefore, RTS tests after ACLR should at least comprise a hop test battery or the hop-and-hold test to reduce second ACL injury risk after return to pivoting sport. Also, one-third of all athletes mentioned fear of reinjury as the main reason for not returning to their preinjury (level of) sport. This psychological component should be taken seriously and discussed during rehabilitation.

Rehabilitation and Return to Sport Testing After Anterior Cruciate Ligament Reconstruction: Where Are We in 2022?

Athletes who sustain an anterior cruciate ligament (ACL) injury often opt for an ACL reconstruction (ACLR) with the goal and expectation to return to sports at the preinjury level. The proportion of athletes who successfully return to preinjury-level sport is low and disappointing, whereas the rate of second ACL injury in athletes under the age of 20 has been reported to be as high as 40% after return to sport (RTS). Although in recent years, new insights pertaining to RTS have been published, the lack of validity of RTS criteria after ACLR remain. The purpose of this clinical commentary is to present a critical overview of the current literature on RTS testing after ACLR.

Energy Absorption Contribution Deficits in Participants Following Anterior Cruciate Ligament Reconstruction: Implications for Second Anterior Cruciate Ligament Injury

Context: Lower-extremity loading patterns change after anterior cruciate ligament reconstruction (ACLR). However, there is limited research regarding energy absorption contribution (EAC) of athletes following ACLR who reinjure their ACL and those who do not. EAC can be utilized as a measure of joint loading during tasks. Design: Cross-sectional study. Methods: Three groups of individuals (13 in each group) with matched age, sex, height, weight, and sports were enrolled. Data were collected at time of return-to-sport testing for the 2 ACLR groups. An 8-camera 3D motion capture system with a sampling rate of 120 Hz and 2 force plates capturing at 1200 Hz were used to capture joint motions in all 3 planes during a double-limb jump landing. Results: Participants in the ACLR no reinjury and ACLR reinjury groups had significantly greater hip EAC (55.8 [21.5] and 56.7 [21.2]) compared with healthy controls (19.5 [11.1]), P < .001 and P < .001, respectively. The ACLR no reinjury and ACLR reinjury groups had significantly lower knee EAC (24.6 [22.7] and 27.4 [20.8]) compared with healthy controls (57.0 [12.2]), P < .001 and P < .001, respectively. However, the ACLR reinjury group had significantly lower ankle EAC (15.9 [4.6]) than healthy controls (23.5 [6.6]), whereas there was no statistical difference between the ACLR no reinjury group (19.7 [7.8]) and healthy controls. Conclusions: Athletes who had a second ACL injury after ACLR, and those without second ACL injury, appear to have similar hip, knee, and ankle joint loading of the surgical limb at return-to-sport testing. Nevertheless, joint loading patterns were significantly different from healthy controls. The study suggests that EAC as a measure of joint loading during a double-limb jump landing at time of return to sport may not be a strong predictor for second injury following ACLR.

Early Return to Sports to Continue the Season after Anterior Cruciate Ligament Injury Is Not Recommended for Student Athletes

Objective:

The objectives of this study were to investigate whether student athletes with anterior cruciate ligament (ACL) injuries who returned to sports (RTS) without reconstruction could continue their sporting activities until the end of the season and whether there was an increase in secondary damage associated with knee instability.

Methods:

Altogether, 288 skeletally mature patients aged <25 years with new-onset isolated primary ACL injuries were included. Of these, 20 student athletes continued playing sports without ACL reconstruction to try to finish the season and were classified as the early return to sports (ERS) group; the remaining 268 patients, who immediately quit sports and underwent surgery, were classified as the non-ERS group. Knee symptoms and sporting performance for the rest of the season were assessed for the ERS group. The presence of secondary damage, e.g., meniscus injuries and chondral lesions, associated with instability were compared between the two groups.

Results:

Fourteen ERS-group athletes (70%) indicated that their knees had given way during sporting activities, and seven athletes (35%) were unable to complete the season. In the ERS group, the mean self-estimated performance level after injury was 3.8 ± 2.5 (numeric rating scale 0–10). Despite the RTS period being relatively short, medial meniscus tears (P <0.001) significantly increased in the ERS group, and three patients experienced locking of the medial meniscus and required immediate surgery.

Conclusions:

Although ERS without reconstruction to complete the season may be a reasonable strategy for ACL injury, patients’ self-estimated performance level was low and meniscal and cartilage injury rates significantly increased.

Adolescents Have Twice the Revision Rate of Young Adults After ACL Reconstruction With Hamstring Tendon Autograft: A Study From the Swedish National Knee Ligament Registry

Background:

Previous studies have identified young age as a risk factor for anterior cruciate ligament (ACL) revision. However, few studies have looked separately at pediatric patients and adolescents with regard to outcomes after ACL reconstruction.

Purpose:

To determine whether patient age at ACL reconstruction affects the risk of undergoing revision surgery in young patients.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study was based on data from the Swedish National Knee Ligament Registry. Patients aged 5 to 35 years who underwent a primary ACL reconstruction with a hamstring tendon autograft between January 1, 2005, and December 31, 2015, were included. The cohort was stratified into different age groups of pediatric patients, adolescents, and young adults to estimate patients with open, recently closed, and closed epiphyses, respectively. The primary endpoint was ACL revision. A multivariable Cox regression model was used to assess the ACL revision rate. The results were expressed as hazard ratios (HRs) and 95% CIs.

Results:

A total of 36,274 ACL reconstructions were registered during the study period. Of these, 2848 patients were included in the study: 47 pediatric patients (mean age, 13.6 years; range, 9-15 years), 522 adolescents (mean age, 17.4; range, 14-19 years), and 2279 young adults (mean age, 27.0; range, 20-35 years). A total of 31 patients (1.1%) underwent ACL revision within 2 years (0 pediatric patients, 9 adolescents [1.7%], and 22 young adults [1.0%]) and a total of 53 patients (2.6%) underwent ACL revision within 5 years (2 pediatric patients [6.9%], 15 adolescents [3.9%], and 36 young adults [2.2%]). The adolescent age group had a 1.91 times higher rate of ACL revision compared with the young adults (HR = 1.91 [95% CI, 1.13-3.21]; P = .015). There were no differences in revision rates between the pediatric age group and the young adults (HR = 2.93 [95% CI, 0.88-9.79]; P = .081).

Conclusion:

Adolescents had almost twice the rate of revision ACL reconstruction compared with young adults.

Assessing implementation, limited efficacy, and acceptability of the BEAST tool: A rehabilitation and return-to-sport decision tool for nonprofessional athletes with anterior cruciate ligament reconstruction

OBJECTIVES

To assess the implementation, limited efficacy, and acceptability of the BEAST (better and safer return to sport) tool - a rehabilitation and return-to-sport (RTS) decision tool after anterior cruciate ligament reconstruction (ACLR) in nonprofessional athletes.

DESIGN

Prospective cohort.

PARTICIPANTS

43 nonprofessional pivoting sport athletes with ACLR.

MAIN OUTCOME

Clinician- and athlete-experienced implementation challenges (implementation), changes in quadriceps power, side hop and triple hop performance from 6 to 8 months after ACLR (limited efficacy), athletes' beliefs about the individual rehabilitation and RTS plans produced by the BEAST tool (acceptability).

RESULTS

The BEAST tool was developed and then implemented as planned for 39/43 (91%) athletes. Hop and quadriceps power performance improved significantly, with the largest improvement in involved quadriceps power (standardised response mean 1.4, 95% CI:1.1-1.8). Athletes believed the rehabilitation and RTS plan would facilitate RTS (8.2 [SD: 2.0]) and reduce injury risk (8.3 [SD: 1.2]; 0 = not likely at all, 10 = extremely likely).

CONCLUSION

The BEAST tool was implemented with few challenges and adjustments were rarely necessary. Athletes had large improvements in quadriceps power and hop performance on the involved leg. Athletes believed that the individual rehabilitation and RTS plans produced by the tool would facilitate RTS and reduce injury risk.

Does sex affect second ACL injury risk? A systematic review with meta-analysis

OBJECTIVE

To determine sex-based differences in risk of a second ACL injury (overall and by laterality) following primary ACL reconstruction in athletes who are attempting to return to sport.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Systematic search of five databases conducted in August 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies reporting sex-based differences in the incidence of second ACL injury in athletes attempting to return-to-sports and who were followed for at least 1 year following primary ACL reconstruction.

RESULTS

Nineteen studies were included in this review, with seven studies excluded from the primary meta-analysis due to high risk of bias. The remaining 12 studies (n=1431 females, n=1513 males) underwent meta-analysis, with all 19 studies included in a sensitivity analysis. Total second ACL injury risk was 21.9% (females: 22.8%, males: 20.3%). Females were found to have 10.7% risk of an ipsilateral ACL injury and 11.8% risk of a contralateral ACL injury. Males were found to have 12.0% risk of an ipsilateral ACL injury and 8.7% risk of a contralateral ACL injury. No statistically significant differences were observed for total second ACL injury risk (risk difference=-0.6%, 95% CI -4.9 to 3.7, p=0.783, I²=41%) or contralateral ACL injury risk (risk difference=1.9%, 95% CI -0.5% to 4.4%, p=0.113, I²=15%) between sexes. Females were found to have a 3.4% absolute risk reduction in subsequent ipsilateral ACL injury risk compared with males (risk difference=-3.4%, 95% CI -6.7% to -0.02%, p=0.037, I²=35%).

CONCLUSION

Both sexes have >20% increased risk of experiencing a second ACL injury. Any difference in the absolute risk of either a subsequent ipsilateral or contralateral ACL injury between sexes appears to be small.

REGISTRATION

PROSPERO (CRD42020148369).

The Role of Psychological Readiness in Return to Sport Assessment After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Knowledge about the predictive value of return to sport (RTS) test batteries applied after anterior cruciate ligament reconstruction (ACLR) is limited. Adding assessment of psychological readiness has been recommended, but knowledge of how this affects the predictive ability of test batteries is lacking.

PURPOSE

To examine the predictive ability of a RTS test battery on return to preinjury level of sport and reinjury when evaluation of psychological readiness was incorporated.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 129 patients were recruited 9 months after ACLR. Inclusion criteria were age ≥16 years and engagement in sports before injury. Patients with concomitant ligamentous surgery or ACL revision surgery were excluded. Baseline testing included single-leg hop tests, isokinetic strength tests, the International Knee Documentation Committee (IKDC) Subjective Knee Form 2000, a custom-made RTS questionnaire, and the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale. The RTS criteria were IKDC 2000 score ≥85% and ≥85% leg symmetry index on hop and strength test. At a 2-year follow-up evaluation, further knee surgery and reinjuries were registered and the RTS questionnaire was completed again. Regression analyses and receiver operating characteristic analyses were performed to study the predictive ability of the test battery.

RESULTS

Out of the 103 patients who completed the 2-year follow-up, 42% returned to their preinjury level of sport. ACL-RSI 9 months after surgery (odds ratio [OR], 1.03) and age (OR, 1.05) predicted RTS. An ACL-RSI score <47 indicated that a patient was at risk of not returning to sport (area under the curve 0.69; 95% CI, 0.58-0.79), with 85% sensitivity and 45% specificity. The functional tests did not predict RTS. Six patients sustained ACL reinjuries and 7 underwent surgery for other knee complaints/injuries after RTS testing. None of the 29 patients who passed all RTS criteria, and were therefore cleared for RTS, sustained a second knee injury.

CONCLUSION

ACL-RSI and age were predictors of 2-year RTS, while functional tests were not informative. Another main finding was that none of the patients who passed the 85% RTS criteria sustained another knee injury.

How does anterior cruciate ligament reconstruction affect the functioning of the brain and spinal cord? A systematic review with meta-analysis

OBJECTIVE

To examine the effect of anterior cruciate ligament (ACL) reconstruction on spinal-reflex and corticospinal excitability of the quadriceps muscle.

METHODS

A comprehensive electronic database search was performed to identify studies that objectively measured Hoffmann reflex to muscle response ratio, motor threshold, and motor evoked potentials after ACL reconstruction. Pooled standardized mean differences (SMDs) were computed using a random effects meta-analysis model.

RESULTS

A total of 13 studies were eligible for analysis. The Hoffmann reflex to muscle response ratio was significantly higher on both the reconstructed and non-reconstructed legs when compared with the healthy control leg (SMD = 0.28, 95% confidence interval (95%CI): 0.08-0.49, p = 0.006 and SMD = 0.22, 95%CI: 0.04-0.40, p = 0.016, respectively) but did not differ between legs (SMD = 0.10, 95%CI: -0.01 to 0.21, p = 0.078). The motor threshold was significantly higher on both the reconstructed (SMD = 0.76, 95%CI: 0.40-1.12, p < 0.001) and non-reconstructed legs (SMD = 0.47, 95%CI: 0.00-0.95, p = 0.049) when compared with the legs of healthy controls. The reconstructed leg also had a higher motor threshold when compared with the non-reconstructed leg (SMD = 0.20, 95%CI: 0.06-0.34, p = 0.005). These changes were paralleled by bilateral reductions in quadriceps strength (ACL reconstructed: SMD = -0.78, 95%CI: -1.07 to -0.49, p < 0.001; non-reconstructed: SMD = -0.32, 95%CI: -0.63 to -0.01, p = 0.042) and quadriceps voluntary activation (ACL reconstructed: SMD = -0.73, 95%CI: -0.97 to -0.50, p < 0.001; non-reconstructed: SMD = -0.55, 95%CI: -0.82 to -0.27, p < 0.001) when compared with healthy controls.

CONCLUSION

There is increased excitability of the spinal-reflex pathways and reduced excitability of the corticospinal pathways following ACL reconstruction. These changes are paralleled by reductions in quadriceps strength and voluntary activation, suggesting that rehabilitation interventions should focus on normalizing the excitability of neural pathways to effectively address quadriceps dysfunction after ACL reconstruction.

Editorial Commentary: Autograft Beats Allograft for Most Knee Ligament Surgery

Knee ligament reconstruction can be performed with autograft or allograft. The use of an autograft has been shown to improve outcomes in primary anterior cruciate ligament reconstruction for young, active patients, and also in revision anterior cruciate ligament reconstruction surgery. A systematic review of posterior cruciate ligament reconstruction showed no difference in outcomes between autograft and allograft tissue. There is a paucity of data comparing autograft versus allograft for fibular collateral ligament and posterolateral corner reconstructions, alone or combined with other ligament surgery. Allograft advantages include no donor site morbidity and reduced operative time. Disadvantages include increased cost and higher failure rates in younger patients. Autograft tissue should be considered in younger, active patients whenever possible.

Rehabilitation characteristics and patient barriers to and facilitators of ACL reconstruction rehabilitation: A cross-sectional survey

OBJECTIVES

To investigate patient-reported rehabilitation characteristics and barriers to and facilitators of ACL reconstruction rehabilitation.

DESIGN

Survey-based study.

SETTING

Online survey platform.

PARTICIPANTS

Adults 1-20 years post ACL reconstruction (n = 304).

MAIN OUTCOME MEASURES

1) rehabilitation characteristics, 2) barriers to and facilitators of rehabilitation.

RESULTS

Fear of re-injury (43.8%) was the highest rating barrier to rehabilitation adherence, while a good relationship with your rehabilitation provider was regarded as the most important factor (83.6%) in facilitating rehabilitation. Rehabilitation frequency reduced across the duration of rehabilitation from most commonly 1 x week (38.2%) in the first three months to once every month (26%) from 6 to 9 months. Almost all participants (95.7%) consulted a rehabilitation provider for the first six months. Only 43.4% of respondents returned to their previous level of sport. The exploratory analysis identified that low barriers to rehabilitation and a longer duration of supervised rehabilitation are associated with a faster return to sport, greater likelihood of return to previous level of sport and fewer reported ongoing problems with the knee.

CONCLUSIONS

This cross-sectional survey provides insight into the patient's experience of rehabilitation practices and a patient's perspective on the key barriers to and facilitators of ACL rehabilitation adherence and participation.

Does sensorimotor function predict graft rupture, contra-lateral injury or failure to return to sports after ACL reconstruction? A protocol for the STOP Graft Rupture study

INTRODUCTION

People with anterior cruciate ligament (ACL) reconstruction (ACLR) are at high risk of sustaining a graft rupture and/or contra-lateral ACL injury. The main factors that may predispose individuals for subsequent ACL injuries are, however, not established. To reduce the risk of reinjuries, it is of particular interest to identify modifiable risk-factors, for instance, those related to sensorimotor control which are responsive to training. The aim of the current study protocol is to present the design of our prospective cohort study STOP Graft Rupture investigating sensorimotor function as predictors for graft rupture, contra-lateral ACL injury and/or failure to return to sport (RTS) within 3 years following ACLR.

METHODS AND ANALYSIS

We aim to recruit 200 individuals (15-35 years, ~50% women) with ACLR from Norrland University Hospital, Umeå and Lund University Hospital, Lund, Sweden. Participants will be assessed with a comprehensive test battery for sensorimotor muscle function, including hop performance, muscle strength, muscle activation, hip and ankle range of motion and postural orientation as well as patient-reported function 1 year after ACLR (baseline). For a subgroup of individuals (Umeå cohort), 3D kinematics and joint position sense will also be evaluated. At follow-up (≥3 years post-ACLR), the participants will be asked to answer questions related to new ACL injuries to either knee and about RTS. Separate logistic regression models, adjusting for possible confounders, will be used to evaluate the influence of the different sensorimotor predictors on the prospective outcomes (graft rupture, contra-lateral ACL injury, RTS).

ETHICS AND DISSEMINATION

This study was approved by the Swedish Ethical Review Board (Dnr 2016/319 and Dnr 2019-04037). The results will be published in international peer-reviewed scientific journals and presented at clinical and scientific congresses.

TRIAL REGISTRATION NUMBER

NCT04162613.

Quantitative Assessment of In Vivo Human Anterior Cruciate Ligament Autograft Remodeling: A 3-Dimensional UTE-T2* Imaging Study

BACKGROUND

The timing of return to play after anterior cruciate ligament (ACL) reconstruction is still controversial due to uncertainty of true ACL graft state at the time of RTP. Recent work utilizing ultra-short echo T2* (UTE-T2*) magnetic resonance imaging (MRI) as a scanner-independent method to objectively and non-invasively assess the status of in vivo ACL graft remodeling has produced promising results.

PURPOSE/HYPOTHESIS

The purpose of this study was to prospectively and noninvasively investigate longitudinal changes in T2* within ACL autografts at incremental time points up to 12 months after primary ACL reconstruction in human patients. We hypothesized that (1) T2* would increase from baseline and initially exceed that of the intact contralateral ACL, followed by a gradual decline as the graft undergoes remodeling, and (2) remodeling would occur in a region-dependent manner.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twelve patients (age range, 14-45 years) who underwent primary ACL reconstruction with semitendinosus tendon or bone-patellar tendon-bone autograft (with or without meniscal repair) were enrolled. Patients with a history of previous injury or surgery to either knee were excluded. Patients returned for UTE MRI at 1, 3, 6, 9, and 12 months after ACL reconstruction. Imaging at 1 month included the contralateral knee. MRI pulse sequences included high-resolution 3-dimensional gradient echo sequence and a 4-echo T2-UTE sequence (slice thickness, 1 mm; repetition time, 20 ms; echo time, 0.3, 3.3, 6.3, and 9.3 ms). All slices containing the intra-articular ACL were segmented from high-resolution sequences to generate volumetric regions of interest (ROIs). ROIs were divided into proximal/distal and core/peripheral sub-ROIs using standardized methods, followed by voxel-to-voxel registration to generate T2* maps at each time point. This process was repeated by a second reviewer for interobserver reliability. Statistical differences in mean T2* values and mean ratios of T2*_inj/T2*_intact (ie, injured knee to intact knee) among the ROIs and sub-ROIs were assessed using repeated measures and one-way analyses of variance. P < .05 represented statistical significance.

RESULTS

Twelve patients enrolled in this prospective study, 2 withdrew, and ultimately 10 patients were included in the analysis (n = 7, semitendinosus tendon; n = 3, bone-patellar tendon-bone). Interobserver reliability for T2* values was good to excellent (intraclass correlation coefficient, 0.84; 95% CI, 0.59-0.94; P < .001). T2* values increased from 5.5 ± 2.1 ms (mean ± SD) at 1 month to 10.0 ± 2.9 ms at 6 months (P = .001), followed by a decline to 8.1 ± 2.0 ms at 12 months (P = .129, vs 1 month; P = .094, vs 6 months). Similarly, mean T2*_inj/T2*_intact ratios increased from 62.8% ± 22.9% at 1 month to 111.1% ± 23.9% at 6 months (P = .001), followed by a decline to 92.8% ± 29.8% at 12 months (P = .110, vs 1 month; P = .086, vs 6 months). Sub-ROIs exhibited similar increases in T2* until reaching a peak at 6 months, followed by a gradual decline until the 12-month time point. There were no statistically significant differences among the sub-ROIs (P > .05).

CONCLUSION

In this preliminary study, T2* values for ACL autografts exhibited a statistically significant increase of 82% between 1 and 6 months, followed by an approximate 19% decline in T2* values between 6 and 12 months. In the future, UTE-T2* MRI may provide unique insights into the condition of remodeling ACL grafts and may improve our ability to noninvasively assess graft maturity before return to play.

Identifying potential patient-specific predictors for anterior cruciate ligament reconstruction outcome - a diagnostic in vitro tissue remodeling platform

Purpose

Upon anterior cruciate ligament (ACL) rupture, reconstruction is often required, with the hamstring tendon autograft as most widely used treatment. Post-operative autograft remodeling enhances graft rupture risk, which occurs in up to 10% of the patient population, increasing up to 30% of patients aged under 20 years. Therefore, this research aimed to identify potential biological predictors for graft rupture, derived from patient-specific tissue remodeling-related cell properties in an in vitro micro-tissue platform.

Methods

Hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions (36 patients, aged 12–55 years), and seeded in collagen I gels on a micro-tissue platform. Micro-tissue compaction over time – induced by altering the boundary constraints – was monitored. Pro-collagen I expression was assessed using ELISA, and protein expression of tenomodulin and α-smooth muscle actin were measured using Western blot. Expression and activity of matrix metalloproteinase 2 were determined using gelatin zymography.

Results

Only micro-tissues corresponding to younger patients occasionally released themselves from the constraining posts. Pro-collagen I expression was significantly higher in younger patients. Differences in α-smooth muscle actin and tenomodulin expression between patients were found, but these were age-independent. Active matrix metalloproteinase 2 expression was slightly more abundant in younger patients.

Conclusions

The presented micro-tissue platform exposed patient-specific remodeling-related differences between tendon-derived cells, with the micro-tissues that released from constraining posts and pro-collagen I expression best reflecting the clinical age-dependency of graft rupture. These properties can be the starting point in the quest for potential predictors for identifying individual patients at risk for graft rupture.