Contralateral anterior cruciate ligament injury after anterior cruciate ligament reconstruction: a case controlled study

Objectives:To investigate the association between generalized joint hypermobility (GJH) and the 24-month incidence of a second ipsilateral or contralateral anterior cruciate ligament (ACL) injury in a population of patients who return to sport (RTS) after ACL reconstruction (ACL-R).Methods:Data for this study were queried from a Swedish rehabilitation specific registry called Project ACL. Ethical approval for this project was granted by the Regional Ethical Review Board in Sweden (registration numbers: 265-13, T023-17) and the Swedish Ethical Review Authority (registration number: 2020-02501). Patients with a primary ACL tear treated with ACL-R who were 16-50 years old and registered in Project ACL between 2014 – 2019 were considered eligible for inclusion. Return to sport was defined as a return to ³6 Tegner activity level. Patients with 5 positive tests on the Beighton scale were considered to fulfill criteria for GJH. Patients with missing GJH data, and patients with Tegner activity level <6 preoperatively or at the time of RTS were excluded from further analysis. The study population was divided into GJH and non-GJH groups based on the screening criteria. The extracted data for eligible patients consisted of demographics, surgical variables and patient reported outcome measures (Table 1). Incidence of a second (ipsilateral or contralateral) ACL injury during the follow-up period after ACL-R was registered as a dichotomous variable. Demographic, injury-related, surgical and follow-up data were reported using descriptive statistics including frequency (n) and proportion (%) for categorical variables and mean ± standard deviation (SD) or median with range for continuous variables. For comparison between groups Fisher’s Exact test was used for dichotomous variables, Chi Square Exact test was used for non-ordered categorical variables and the Fisher’s Non Parametric Permutation Test was used for continuous variables. Univariable logistic regression was performed to determine the influence of GJH and timing of RTS (Tegner activity level ³ 6) on the odds of a second ACL injury following ACL-R within 2 years of RTS.Results:A total of 153 patients were deemed eligible for this study. Primary ACL-R was performed in 34 (22%) patients with GJH and 119 (78%) non-GJH patients. Patients with GJH were younger at the time of ACL-R (21.8 vs 24.5 years; p = 0.049) and had a shorter time from surgery to RTS (8.1 vs. 10.3 months; p = 0.044). Within 24 months of RTS, 6 (17.6%) patients with GJH and 3 (2.5%) non-GJH patients had a second ACL injury (p = 0.0082). Return to preinjury Tegner activity level was achieved by 29 (85.3%) GJH patients and 114 (74.5%) non-GJH patients (p = 0.15; Table 1). There was no statistically significant difference in preoperative and postoperative Knee Injury and Osteoarthritis Outcome Score subscales and psychometric measures of risk appraisal at RTS between the GJH and non-GJH groups (Table 2). The odds of sustaining a second ACL injury was 8.29 in GJH compared to non-GJH patients (95% confidence interval = 1.95-35.18; p = 0.0042; area under the receiver operating characteristic curve = 0.74; Table 3).Conclusions:Patients with GJH undergoing ACL-R have an 8 times greater odds of sustaining a second ACL injury after RTS. Consequently, GJH should be considered a risk-factor for repeat ipsilateral or contralateral ACL injury, and the importance of joint laxity assessment should be emphasized in patients who aim to return to high-intensity sports following ACL-R.Table 1.Comparison of baseline demographic variables and the incidence of a second ACL injury between GJH and non-GJH patientsTable 2.Comparison of Tegner activity level and patient reported outcome measures between GJH and non-GJH patients at the time of surgey and RTSTable 3.Univariable logistic regression anlaysis performed to assess the influence of GJH and time until return to Tegner activity level >6 on sustaining a second ACL injury within two years of RTS after ACL-R

Contralateral anterior cruciate ligament (ACL) injuries are together with the risk of developing osteoarthritis of the knee and the risk of re-rupture/graft failure important aspects to consider after an ACL injury. The aim of this review was to perform a critical analysis of the literature on the risk factors associated with a contralateral ACL injury. A better understanding of these risk factors will help in the treatment of patients with unilateral ACL injuries and in the development of interventions designed to prevent contralateral ACL injuries. A Medline search was conducted to find studies investigating risk factors for a contralateral ACL injury, as well as studies where a contralateral ACL injury was the outcome of the study. Twenty studies describing the risk of a contralateral ACL rupture, or specific risk factors for a contralateral ACL injury, were found and systematically reviewed. In 13 of these studies, patients were followed prospectively after a unilateral ACL injury. The evidence presented in the literature shows that the risk of sustaining a contralateral ACL injury is greater than the risk of sustaining a first time ACL injury. Return to a high activity level after a unilateral ACL injury was the most important risk factor of sustaining a contralateral ACL injury. There was inconclusive evidence of the relevance of factors such as female gender, family history of ACL injuries, and a narrow intercondylar notch, as risk factors for a contralateral ACL injury. Risk factors acquired secondary to the ACL injury, such as altered biomechanics and altered neuromuscular function, affecting both the injured and the contralateral leg, most likely, further increase the risk of a contralateral ACL injury. This literature review indicates that the increased risk of sustaining a contralateral ACL injury should be contemplated, when considering the return to a high level of activity after an ACL injury.

Background: Contralateral anterior cruciate ligament (CACL) injury after recovery from a first-time ACL rupture occurs at a high rate in young females; however, little is known about the risk factors associated with bilateral ACL trauma. Hypothesis: The geometric characteristics of the contralateral knee at the time of the initial ACL injury are associated with risk of suffering a CACL injury in these female athletes. Study Design: Case-control study; Level of evidence, 3. Methods: Sixty-two female athletes who suffered their first noncontact ACL injury while participating in sports at the high school or college level were identified, and geometry of the femoral notch, ACL, tibial spines, tibial subchondral bone, articular cartilage surfaces, and menisci of the contralateral, uninjured, knee was characterized in 3 dimensions. We were unable to contact 7 subjects and followed the remaining 55 until either a CACL injury or an ACL graft injury occurred or, if they were not injured, until the date of last contact (mean, 34 months after their first ACL injury). Cox regression was used to identify risk factors for CACL injury. Results: Ten (18.2%) females suffered a CACL injury. Decreases of 1 SD in femoral intercondylar notch width (measured at its outlet and anterior attachment of the ACL) were associated with increases in the risk of suffering a CACL injury (hazard ratio = 1.88 and 2.05, respectively). Likewise, 1 SD decreases in medial-lateral width of the lateral tibial spine, height of the medial tibial spine, and thickness of the articular cartilage located at the posterior region of the medial tibial compartment were associated with 3.59-, 1.75-, and 2.15-fold increases in the risk of CACL injury, respectively. Conclusion: After ACL injury, subsequent injury to the CACL is influenced by geometry of the structures that surround the ACL (the femoral notch and tibial spines). This information can be used to identify individuals at increased risk for CACL trauma, who might benefit from targeted risk-reduction interventions.

Objectives: The ability of current return to sport (RTS) criteria to identify young, active patients after ACL reconstruction (ACLR) independently, at high risk for future ipsilateral or contralateral ACL injury is limited. The purpose of this study was to determine if meeting current, standard RTS criteria collectively, or in part, would identify young athletes at risk for an ipsilateral or contralateral ACL injury after primary ACLR and RTS. The tested hypothesis was the likelihood of an ipsilateral or contralateral 2nd ACL injury in the first 2 years after RTS would be the same in groups that successfully met or failed to meet all RTS criteria prior to RTS. The second hypothesis was that quadriceps femoris strength at the time of RTS would identify which limb was at greatest risk for future ACL injury. Methods: One hundred eighty-one patients (116 female) with a mean age of 16.7±2.9 years old underwent ACLR and were released to return to pivoting/cutting sports. These patients were enrolled in a prospective, observational cohort study, completed a RTS assessment and were tracked for occurrence of an ipsilateral graft tear or contralateral ACL injury after ACLR for 24 months. The RTS assessment included 6 tests: isometric quadriceps strength, 4 functional hop tests and the International Knee Documentation Committee (IKDC) patient reported outcome survey. Limb symmetry index (LSI) was calculated for strength and hop test assessments [(inv/uninv)*100]. Subjects were classified into groups that successfully passed all 6 RTS tests at a level of 90 compared to those that failed to meet all 6 criteria. Chi Square tests and Fisher Exact Tests were used to determine if successfully passing all 6 RTS measures resulted in a reduced risk of 2nd ACL injury in the first 24 months after RTS as well as to assess if ability to successfully pass individual RTS criteria resulted in reduced risk of 2nd ACL injury. Results: Thirty-nine (21.5%) patients suffered a 2nd ACL injury with 18 ipsilateral graft failures and 21 contralateral ACL tears in the first 24 months after RTS following ACLR. At the time of RTS, 57 patients (31.5%) achieved LSI values of 90% or greater on all testing as well as an IDKC value of 90 or greater. At this level, there was no difference in ipsilateral graft failures between patients who passed all RTS criteria (15.8%) and those who failed at least 1 criterion (7.3%; p=0.08). There was also no difference in contralateral ACL injuries between patients who passed all RTS criteria (7.0%) and those who failed at least 1 criterion (13.7%; p=0.22). When individual RTS criterion were evaluated, patients who failed to achieve 90% quadriceps strength LSI were 84% less likely to suffer an ipsilateral graft failure (OR=0.16; 95%CI: 0.04, 0.74;p=0.009), but 3 times more likely to suffer a contralateral ACL injury (OR=2.5; 95%CI:1.0, 6.5;p=0.05). Conclusion: Current criteria to evaluate readiness to return young athletes to pivoting and cutting sports, may not identify young, active patients independently at high risk for a future ipsilateral graft tear or contralateral ACL injury. Inability to achieve 90% LSI on an isometric quadriceps strength assessment resulted in a reduced risk of ipsilateral graft failure, but an increased risk in contralateral ACL injury after ACLR and RTS. Further investigation is needed on the relationship between quad strength and side of future ACL injury and whether other factors may help contribute to a predictive model of future ACL injury specific to limb.

Objectives:The incidence of second anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) and return to sport (RTS) in a young, active population is likely between 25-33% with the greatest risk in the first 12 months after RTS. Although the use of allograft tissue in young athletes has been reported to result in increased risk of graft failure, differences in graft and contralateral ACL injury risk between patients who receive a hamstrings (HS) autograft and bone-patellar tendon- bone (BTB) autograft has yet to be reported in a young, athletic population. The tested hypothesis was that the relative risk (RR) of ipsilateral graft failure would be higher in young, active patients who receive an ACLR with a hamstrings graft, while the RR of contralateral ACL injury would be higher in patients who receive and ACLR with a BTB autograft.Methods:One hundred thirty-nine subjects (99 female/40 male) with a mean age of 16.9±2.0 years old (range: 13-25 y/o) underwent ACLR with either a HS autograft (n=79) or a BTB autograft (n=60) and were released to return to pivoting/cutting sport. These patients were enrolled in a prospective, observational cohort study and were tracked for incidence of 2nd ACL after ACLR for a median of 73 months. Thirty-four (24.5%) suffered a 2nd ACL injury. Fisher’s exact tests were used to determine whether graft choice (HS vs. BTB) was associated with risk of either ipsilateral graft failure or contralateral ACL injury. Sub-group analyses by sex were also conducted.Results:Patients who underwent ACLR with HS graft (n=79) sustained 14 ipsilateral tears and 6 contralateral ACL injuries. Patients who received an ACLR with BTB (n=62) sustained 2 ipsilateral tears and 12 contralateral ACL injuries (Table 1). Patients who received an ACLR with HS graft were 6 times more likely (RR=6.2; 95% CI: 1.4-28.7) to suffer a graft failure after RTS than the BTB group. In the first 12 months after RTS, the HS graft patients were nearly 10 times (RR=9.5; 95% CI: 1.2-76.1) more likely to suffer an ipsilateral graft failure. Patients with a HS graft were 3 times less likely (RR=0.33; 95%CI: 0.12-0.935) to suffer a contralateral ACL injury and nearly 7 times less likely (RR=0.15, 95%CI: 0.031-0.709) to suffer a contralateral ACL injury in the first 12 months after RTS compared to the BTB group. When the cohort was divided by sex, females with HS grafts were significantly more likely to sustain a graft failure in the first 12 months after RTS (p=0.008) and by final follow-up (p=0.002) compared to females with BTB graft. Females with HS grafts were 3 times less likely (RR=0.30; 95%CI: 0.095-0.943) to suffer a contralateral ACL injury than females with BTB graft and 6 times less likely (RR=0.17; 95%CI: 0.034-0.846) to suffer contralateral ACL injury in the first year after RTS. Males demonstrated no significant difference in ipsilateral or contralateral injury risk based on graft type.Conclusion:Young, active females who return to pivoting and cutting sports after ACLR with HS autograft are at greater risk to suffer a graft failure and reduced risk to suffer a contralateral ACL injury compared to females who undergo ACLR with BTB graft tissue. No significant differences in 2nd ACL injury risk based on graft type were observed in the male patients.Table 1:Distribution of 2nd ACL Injury after ACLR and Return to Sport (RTS)All Subjects (n=139)HS (n=79)BTB (n=60)p-valueIpsilateral (RTS+1 year)11 (13.9%)1 (1.7%)0.013Ipsilateral (Overall)14 (17.7%)2 (3.4%)0.014Contralateral (RTS+1 year)2 (2.2%)9 (15.0%)0.010Contralateral (Overall)6 (7.6%)12 (20.0%)0.031Female (n=99)HS (n=55}BTB (n=44)p-valueIpsilateral (RTS+l year)8 (14.5%)0 (0%)0.008Ipsilateral (Overall)10 (18.2%)0 (0%)0.002Contralateral (RTS+1 year)2 (3.6%)8 (18.2%)0.021Contralateral (Overall)5 (9.1%)11 (25.0%)0.033Male (n=40)HS (n=24)BTB (n=16)p-valueIpsilateral (RTS+1 year)3 (12.5%)1 (6.2%)0.638Ipsilateral (Overall)4 (16.7%)2 (12.5%)1.000Contralateral (RTS+I year)0 (0%)1 (6.2%)0.400Contralateral (Overall)1 (4.2%)1 (6.2%)1.000

BackgroundThe risk of sustaining a contra-lateral anterior cruciate ligament (C-ACL) injury after primary unilateral ACL injury is high. C-ACL injury often contributes to a further decline in function and quality of life, including failure to return to sport. There is, however, very limited knowledge about which risk factors that contribute to C-ACL injury.ObjectiveTo systematically review instrinsic risk factors for sustaining a C-ACL injury.MethodsA systematic review with meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Four databases (MEDLINE, CINAHL, EMBASE, Sport Discus) were searched from inception to January 2020. Inclusion criteria were prospective or retrospective studies investigating any intrinsic risk factor for future C-ACL injury. Meta-analysis was performed and expressed as odds ratios (OR) if two or more articles assessed the same risk factor.Results44 moderate-to-high quality studies were eventually included in this review, whereof 35 studies were eligible for meta-analysis, including up to 59 000 individuals. We identified seven factors independently increasing the odds of sustaining a C-ACL injury (in order of highest to lowest OR): (1) returning to a high activity level (OR 3.26, 95% CI 2.10–5.06); (2) Body Mass Index < 25 (OR 2.73, 95% CI 1.73–4.36); (3) age ≤ 18 years (OR 2.42, 95% CI 1.51–3.88); (4) family history of ACL injury (OR 2.07, 95% CI 1.54–2.80); (5) primary ACL reconstruction performed ≤ 3 months post injury (OR 1.65, 95% CI: 1.32–2.06); (6) female sex (OR 1.35, 95% CI 1.14–1.61); and (7) concomitant meniscal injury (OR 1.21, 95% CI 1.03–1.42). The following two factors were associated with decreased odds of a subsequent C-ACL injury: 1) decreased intercondylar notch width/width of the distal femur ratio (OR 0.43, 95% CI 0.25–0.69) and 2) concomitant cartilage injury (OR 0.83, 95% CI 0.69–1.00). There were no associations between the odds of sustaining a C-ACL injury and smoking status, pre-injury activity level, playing soccer compared to other sports or timing of return to sport. No studies of neuromuscular function in relation to risk of C-ACL injury were eligible for meta-analysis according to our criteria.ConclusionThis review provides evidence that demographic factors such as female sex, young age (≤ 18 years) and family history of ACL injury, as well as early reconstruction and returning to a high activity level increase the risk of C-ACL injury. Given the lack of studies related to neuromuscular factors that may be modifiable by training, future studies are warranted that investigate the possible role of factors such as dynamic knee stability and alignment, muscle activation and/or strength and proprioception as well as sport-specific training prior to return-to-sport for C-ACL injuries.PROSPERO: CRD42020140129.

Objectives:Bony morphologic characteristics have been demonstrated to increase the risk of anterior cruciate ligament (ACL) injury. While posterior femoral condyle condylar offset is an aspect of distal femoral bony morphology that has been reported to influence range of motion and other aspects of knee joint kinematics, it remains unclear whether this characteristic influences the risk of ACL injury. The purpose of the study was to examine the relationship between distal femoral morphology and risks of ACL injury, reconstruction failure, and contralateral ACL injury. It was hypothesized that increased posterior femoral condylar depth, quantified as the cam ratio, would correlate with increased risk of primary ACL injuries, ACL reconstruction failures, and contralateral ACL injuries.Methods:Consecutive patients undergoing evaluation for knee complaints at an academic medical center from 2012-2016 with minimum 24-month follow-up were retrospectively reviewed. Subjects were stratified into four groups: a control group consisting of patients with no ACL injuries and three groups of patients with a primary ACL injury, failed ACL reconstruction, or previous ACL injury with subsequent contralateral ACL injury. Using lateral radiographs, the ratio of posterior condylar depth over total condylar distance was defined as the cam ratio. Analysis-of-variance (ANOVA) and post-hoc testing were used to test for differences in the mean tomahawk ratio between study groups (p<0.05). Receiver Operating Characteristic (ROC) analysis was performed to determine the optimal cam ratio cut-off for detecting increased risk for ACL injury.Results:One hundred and seventy-five patients met inclusion criteria. The mean cam ratios in the control, primary ACL injury, failed ACL reconstruction, and contralateral ACL injury groups were 61.1% (± 2.1), 64.2% (± 3.8), 64.4% (± 3.6), and 66.9% (± 4.0), respectively. Patients with a primary ACL injury, failed ACL reconstruction, or contralateral ACL injury had a significantly higher cam ratio compared to the control group (p<0.008). ROC analysis demonstrated a cam ratio of 63% or greater to be associated with an increased risk for ACL injury with a sensitivity of83% and a specificity of 71%.Conclusion:The data from this study show that an increased posterior femoral condylar depth, or cam ratio, might be associated with increased risk of ACL injury, including primary ACL injury, failed ACL reconstruction, and contralateral ACL injury. The data from this study may help clinicians identify patients at greater risk of ACL injury and re-injury. Future prospective studies will be helpful in investigating the mechanism by which an increased cam ratio increases ACL injury risk and potential strategies to mitigate the increased risk posed by this bony characteristic.

To investigate the risk factors of contralateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction. A retrospective review was conducted on the 716 patients with ACL injury who received primary ACL reconstruction surgery and met the selection criteria between January 2012 and September 2018. After a mean follow-up period of 7.6 years (range, 4-10 years), 65 patients (9.1%) experienced contralateral ACL injury (injured group) and 651 patients (90.9%) did not (uninjured group). There was no significant difference in age, body mass index, and preoperative Lachman test degree between groups ( P>0.05). However, the proportion of female in the injured group was significantly higher than that of male ( P<0.05), and the preoperative posterior tibial slope (PTS) was significantly higher than that of the uninjured group ( P<0.05). Using the outcome of contralateral ACL injury as the dependent variable, the clinical data of the patient was first used as the independent variable, and univariate COX regression was used to analyze the prognostic influencing factors. Then, the indicators with differences in univariate COX regression were used as the independent variable, and multivariate COX regression was used to analyze the independent risk factors affecting prognosis. Log-Rank (Mantel-Cox) test was used to test and analyze the occurrence time of contralateral ACL injury in patients of different genders; X-tile software was used to analyze the occurrence time of contralateral ACL injury in patients with different PTS using Log-Rank (Mantel-Cox) test and PTS cut-off values. Univariate COX regression analysis showed that gender and PTS were influence factors for contralateral ACL injury ( P<0.05); further multivariate COX regression analysis showed that female and increased PTS were independent risk factors for contralateral ACL injury ( P<0.05). The Log-Rank (Mantel-Cox) test results showed that the contralateral ACL injury occurred in female at 8.853 (8.600, 9.106) years, which was significantly shorter than that in male [9.661 (9.503, 9.819) years] ( χ 2=20.323, P<0.001). Using X-tile software to analyze the cut-off value of PTS, it was found that the cut-off value of PTS for contralateral ACL injury was 10.92°. According to the Log-Rank (Mantel-Cox) test, it was found that the contralateral ACL injury occurred in 5.762 (4.981, 6.543) years in patients with PTS≥10.92°, which was significantly shorter than patients with PTS<10.92° [9.751 (9.650, 9.853) years]( χ 2 =302.479, P<0.001). Female and PTS≥10.92° after primary ACL reconstruction are independent risk factors for contralateral ACL injury.

Aims and Objectives:Bony morphologic characteristics have been demonstrated to increase the risk of anterior cruciate ligament (ACL) injury. The purpose of the study was to examine distal femoral morphology relative to ACL injury, reconstruction failure, and contralateral ACL injury.It was hypothesized that an increased posterior femoral condylar depth, quantified as the tomahawk ratio, would correlate with increased risk of primary ACL ruptures, ACL reconstruction failures, and contralateral ACL injuries.Materials and Methods:Consecutive patients undergoing arthroscopic knee surgery at an academic medical center from 2012-2016 with minimum 24-month follow-up were retrospectively reviewed. Subjects were stratified into four groups: a control group consisting of patients with no ACL injuries and three groups of patients with a primary ACL injury, failed ACL reconstruction, or previous ACL injury with subsequent contralateral ACL injury. Using lateral radiographs, the ratio of posterior condylar depth over total condylar distance was defined as the tomahawk ratio. Analysis-of-variance (ANOVA) and post-hoc testing were used to test for differences in the mean tomahawk ratio between study groups (p<0.05). Receiver Operating Characteristic (ROC) analysis was performed to determine the optimal tomahawk ratio cut-off for detecting increased risk for ACL injuryResults:175 patients met inclusion criteria. The mean tomahawk ratios in the control group, primary ACL injury group, failed ACL reconstruction group, and contralateral ACL injury group were 61.1% (± 2.1), 64.2% (± 3.8), 64.4% (± 3.6), and 66.9% (± 4.0), respectively. Patients with a primary ACL injury, failed ACL reconstruction, or contralateral ACL injury had a significantly higher tomahawk ratio compared to the control group (p<0.008). ROC analysis demonstrated a tomahawk ratio of 63% or greater to be associated with an increased risk for ACL injury with a sensitivity of 83% and a specificity of 71%.Conclusion:The data from this study show that an increased posterior femoral condylar depth, or tomahawk ratio, is associated with increased risk of ACL injury, including primary ACL injury, failed ACL reconstruction, and contralateral ACL injury. Readily identifiable risk factors, such as an increased tomahawk ratio, could assist clinicians in identifying at-risk individuals who may experience greater benefit from targeted ACL injury prevention counseling and intervention. The presence of the tomahawk-shaped femur could also be used to guide treatment decisions and identify ACL reconstruction patients who may benefit from additional surgical procedures such as extra articular tenodesis.

The purpose of this study was to examine the relationship between distal femoral morphology and anterior cruciate ligament (ACL) injury, ACL reconstruction (ACLR) failure, and contralateral ACL injury. It was hypothesized that increased posterior femoral condylar depth, quantified as the lateral femoral condyle ratio, would correlate with increased risk of primary ACL injuries, ACLR failures, and contralateral ACL injuries. The charts of consecutive patients who underwent arthroscopic knee surgery at an academic medical center from 2012 to 2016 with minimum follow-up of 24 months were retrospectively reviewed. Patients were stratified into 4 groups: (1) a control group of patients with no ACL injury, (2) patients with primary ACL injury, (3) patients with failed ACLR, and (4) patients with previous ACL injury and subsequent contralateral ACL injury. With use of lateral radiographs, the ratio of posterior femoral condylar depth to total condylar length was defined as the lateral femoral condyle ratio. Differences between study groups were identified with use of analysis-of-variance (ANOVA) and post-hoc testing with significance set at p < 0.05. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cutoff for detecting increased risk of ACL injury. Two hundred patients met the inclusion criteria. The mean lateral femoral condyle ratios (and standard deviations) were 61.2% ± 2.4% in the control group, 64.2% ± 3.8% in the primary ACL injury group, 64.4% ± 3.6% in the failed ACLR group, and 66.9% ± 4.3% in the contralateral ACL injury group. Patients who had a primary ACL injury, failed ACLR, or contralateral ACL injury had significantly higher ratios compared with the control group (p < 0.008). ROC curve analysis demonstrated that a lateral femoral condyle ratio of >63% was associated with an increased risk for ACL injury, with a sensitivity of 77% and a specificity of 72%. The data from this study show that increased posterior femoral condylar depth, quantified as the lateral femoral condyle ratio, is associated with an increased risk of ACL injury, including primary and contralateral ACL injuries. The data from this study may help clinicians to identify patients at a greater risk of ACL injury. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background: Athletes are twice as likely to rupture the anterior cruciate ligament (ACL) on their healthy contralateral knee than the reconstructed graft after ACL reconstruction (ACLR). Although physical testing is commonly used after ACLR to assess injury risk to the operated knee, strength, jump, and change-of-direction performance and biomechanical measures have not been examined in those who go on to experience a contralateral ACL injury, to identify factors that may be associated with injury risk. Purpose: To prospectively examine differences in biomechanical and clinical performance measures in male athletes 9 months after ACLR between those who ruptured their previously uninjured contralateral ACL and those who did not at 2-year follow-up and to examine the ability of these differences to predict contralateral ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: A cohort of male athletes returning to level 1 sports after ACLR (N = 1045) underwent isokinetic strength testing and 3-dimensional biomechanical analysis of jump and change-of-direction tests 9 months after surgery. Participants were followed up at 2 years regarding return to play or at second ACL injury. Between-group differences were analyzed in patient-reported outcomes, performance measures, and 3-dimensional biomechanics for the contralateral limb and asymmetry. Logistic regression was applied to determine the ability of identified differences to predict contralateral ACL injury. Results: Of the cohort, 993 had follow-up at 2 years (95%), with 67 experiencing a contralateral ACL injury and 38 an ipsilateral injury. Male athletes who had a contralateral ACL injury had lower quadriceps strength and biomechanical differences on the contralateral limb during double- and single-leg drop jump tests as compared with those who did not experience an injury. Differences were related primarily to deficits in sagittal plane mechanics and plyometric ability on the contralateral side. These variables could explain group membership with fair to good ability (area under the curve, 0.74-0.80). Patient-reported outcomes, limb symmetry of clinical performance measures, and biomechanical measures in change-of-direction tasks did not differentiate those at risk for contralateral injury. Conclusion: This study highlights the importance of sagittal plane control during drop jump tasks and the limited utility of limb symmetry in performance and biomechanical measures when assessing future contralateral ACL injury risk in male athletes. Targeting the identified differences in quadriceps strength and plyometric ability during late-stage rehabilitation and testing may reduce ACL injury risk in healthy limbs in male athletes playing level 1 sports. Clinical Relevance: This study highlights the importance of assessing the contralateral limb after ACLR and identifies biomechanical differences, particularly in the sagittal plane in drop jump tasks, that may be associated with injury to this limb. These factors could be targeted during assessment and rehabilitation with additional quadriceps strengthening and plyometric exercises after ACLR to potentially reduce the high risk of injury to the previously healthy knee. Registration: NCT02771548 (ClinicalTrials.gov identifier).

Background:Younger athletes have high rates of second anterior cruciate ligament (ACL) injury. Return-to-sport criteria have been proposed to enable athletes to make a safe return, but they frequently lack validation. It is unclear whether commonly recorded clinical measures can help to identify high-risk athletes.Purpose:To explore the association between commonly recorded clinical outcome measures and second ACL injury in a young, active patient group.Study Design:Cohort study; Level of evidence, 2.Methods:Included in this study were 329 athletes (200 males, 129 females) younger than 20 years at the time of first primary ACL reconstruction surgery who had subsequently returned to sport participation. Clinical examination included range of knee motion (passive flexion and extension deficits), instrumented anterior knee laxity, and single- and triple-crossover hop for distance. Patients also completed the subjective International Knee Documentation Committee form. All measures were collected prospectively at a 12-month postoperative clinical review. Patients were evaluated for a minimum 3 years to determine the incidence of subsequent ACL injury.Results:A total of 95 patients (29%) sustained a second ACL injury following clinical assessment and return to sport. There were 50 graft ruptures and 45 contralateral ACL injuries. Patients with a flexion deficit of 5° had over 2 times the odds of sustaining a graft rupture (odds ratio, 2.3; P < .05), and patients with a side-to-side difference in anterior knee laxity of 3 mm or greater had over 2 times the odds of sustaining a contralateral ACL injury (odds ratio, 2.4; P < .05). Overall, 29% (94 of 329) of patients met the threshold for satisfactory function on all 6 clinical measures; these patients had a 33% reduction in the risk of sustaining a second ACL injury (P = .05) as compared with those who did not meet all clinical thresholds.Conclusion:Clinical measures of knee flexion and stability may have utility to screen for and identify patients who are at greater risk for a second ACL injury in an already high-risk group (ie, age and activity level).

There are inconsistencies in the reported rates of second anterior cruciate ligament (ACL) injuries per limb, patients' sex and graft types after primary ACL reconstruction (ACLR). There are also inconsistencies regarding the influence of these factors on the occurrence of second ACL injury after primary ACLR. To determine the rate of second ACL injury, to either the ipsilateral graft or contralateral healthy ACL, as influenced by sex, age, and graft types and to determine the influence of sex, age, and graft types on the occurrence of second ACL injury after primary ACLR. Systematic review and meta-analysis. A computerized search of MEDLINE, CINAHL, and SPORTDiscus was conducted using combinations of these terms: ACL, ACLR, re-injury, re-rupture, revisions, contralateral tear, ipsilateral graft tear, and second injury. Articles were required to report the number or percentage of sex, graft type, ipsilateral graft and contralateral ACL injuries after ACLR. Rates of second ACL injuries and pooled dichotomous data were calculated using random-effect proportion meta-analysis. The pooled rate of second ACL injuries (ipsilateral graft and contralateral ACL) was 6.11%. A slightly higher rate of ipsilateral graft injuries (3.29%) than contralateral ACL injuries (2.82%) (OR: 1.09 [95%CI: 0.89, 1.34] was reported. Ipsilateral graft injuries occurred earlier (median: 20 months) than contralateral ACL injuries (median: 36.3 months). Men had lower rate of second ACL injuries (5.67%) than women (6.84%) (OR: 0.92 [95%CI: 0.70, 1.20]). Significantly higher rate of ipsilateral graft injuries (3.40%) occurred in men compared to contralateral ACL injuries (2.26%) (OR: 1.53 [95CI%: 1.33, 1.77]), while women had significantly higher rate of contralateral ACL injuries (3.75%) compared to ipsilateral graft injuries (3.09%) (OR: 0.73 [95%CI: 0.55, 0.96]). The rate of second ACL (ipsilateral graft and contralateral ACL) injuries was higher in patients with hamstring tendon (HT) autograft (5.83%) than bone-patella tendon-bone autograft (BPTB) (5.10%) (p = 0.04) and allografts (3.12%) (p<0.0001). The rate of ipsilateral graft injuries was significantly higher than contralateral ACL injuries in all graft types (p<0.001). Injuries to the ipsilateral graft are more common than contralateral ACL, with ipsilateral graft injuries occurring nearly 16 months earlier after ACLR. More women sustain second ACL injuries compared to men, with men incurring more injuries to the ipsilateral graft and women to the contralateral ACL. Furthermore, second ACL injuries are more common in patients with HT autograft, BPTB autograft, and then allograft; with ipsilateral graft injuries higher than contralateral ACL injuries regardless of graft types. 2a.

ObjectivesTo determine the 12-month risk of a second anterior cruciate ligament (ACL) injury in a population of patients with and without generalised joint hypermobility (GJH) who return to sports (RTS)...

<h3>Background</h3> There is limited knowledge about which risk factors that contribute to the high numbers of contra-lateral anterior cruciate ligament (C-ACL) injury after primary ACL injury. <h3>Objective</h3> To systematically review intrinsic risk factors for sustaining a C-ACL injury. <h3>Design</h3> A systematic review with meta-analysis according to the PRISMA guidelines. Four databases (MEDLINE, CINAHL, EMBASE, Sport Discus) were searched from inception to January 2020. Meta-analyses were performed and expressed as odds ratios (OR). <h3>Setting</h3> The included studies describe a variety of sport settings and activity levels. <h3>Participants</h3> The review comprises studies including males and/or females of any age with ACL injury. <h3>Assessment of Risk Factors</h3> The review comprises longitudinal studies investigating any intrinsic risk factor for future C-ACL injury. <h3>Main Outcome Measurements</h3> C-ACL injury <h3>Results</h3> Thirty-five moderate-to-high quality studies were eligible for meta-analysis, including up to ~59 000 individuals. The following factors all independently increased the odds of sustaining a C-ACL: Returning to a high activity level (OR: 3.26, 95% CI: 2.10–5.06), BMI &lt; 25 (OR: 2.73, 95% CI: 1.73–4.36), Age ≤ 18 years (OR: 2.42, 95% CI: 1.51–3.88), Family history of ACL injury (OR: 2.07, 95% CI: 1.54–2.80), Primary ACL reconstruction performed ≤ 3 months post injury (OR: 1.65, 95% CI: 1.32–2.06), Female sex (OR: 1.35, 95% CI: 1.14–1.61) and Concomitant meniscal injury (OR 1.21, 95% CI: 1.03–1.42). There were no associations between the odds of sustaining a C-ACL injury and Smoking status, Pre-injury activity level, Playing soccer compared to other sports or Timing of return to sport. <h3>Conclusions</h3> Demographic factors such as female sex, young age and family history of ACL injury, as well as early reconstruction and returning to a high activity level all contribute to the risk of sustaining a C-ACL injury. Studies on modifiable sensorimotor risk factors are warranted.