Medial meniscal lesions increase antero-posterior laxity in knees with anterior cruciate ligament injury.

PURPOSE: The aim of this study was to quantify the impact of concomitant meniscal lesions on knee laxity using a triaxial accelerometer in a large population of patients affected by anterior cruciate ligament (ACL) injury. METHODS: A total of 326 consecutive patients (261 men and 65 women, mean age 31.3 ± 11.3) undergoing primary ACL reconstruction, were preoperatively evaluated through Lachman and pivot shift tests using a triaxial accelerometer to quantify knee laxity. An analysis based on the presence of meniscal tears assessed during surgery was performed to evaluate the impact of meniscal lesions on knee laxity. RESULTS: The anterior tibial translation (Lachman test) presented significantly higher values in patients with medial meniscal lesions (7.3 ± 1.7 mm, p = 0.049) and both medial and lateral meniscal lesions (7.7 ± 1.6 mm, p = 0.001) compared to patients without concomitant meniscal lesions (6.7 ± 1.3 mm). Moreover, patients with both medial and lateral meniscal lesions presented significantly higher values of anterior tibial translation compared to patients with lateral meniscal lesions (p = 0.049). No statistically significant differences were found between the groups in terms of tibial acceleration (pivot shift test). CONCLUSION: This study demonstrated that the contribution of concomitant meniscal lesions to knee laxity can be objectively quantified using a triaxial accelerometer in ACL-injured knees. In particular, medial meniscus lesions, alone or in association with lateral meniscus lesions, determine a significant increase of the anterior tibial translation compared to knees without meniscus tears. LEVEL OF EVIDENCE: Level IV.

The relevance of knee arthroscopy photographs in medicolegal proceedings.

PURPOSE: Whether photographs included in the operative report of knee arthroscopies can make the surgeon liable in the event of a legal investigation remains unknown. The main objective of this study was to establish inter-observer reliability in determining the presence or absence of lesions of the cartilage, meniscus and anterior cruciate ligament (ACL). Secondary objective was to assess the inter-observer reliability in classifying lesions. METHOD: A retrospective observational study was conducted in a continuous serie of 60 patients who underwent knee arthroscopy from the same operator. The photographs of each patient's operative report were presented separately to three experts, blinded to each other. Each expert had to decide on the presence or absence of injuries to the following structures: meniscal, cartilage and ACL and then, classify it. Primary and secondary endpoints were evaluated using the Fleiss' kappa index. RESULTS: Inter-observer reliability for lesion detection was between 0.4 and 0.61 for all structures with three exceptions: for cartilage, it was low (0.15) at the lateral tibial plateau and poor (-0.01) at the external condyle. On the contrary, the concordance was almost perfect (0.8) for the ACL. For classifying cartilaginous and meniscal lesions, inter-observer reliability was poor (from 0.03 to 0.14), except for at the lateral meniscus (0.65). CONCLUSION: Inter-observer reliability of arthroscopic knee diagnoses is poor when photographs alone are used. In the event of a legal investigation following knee arthroscopy, the photographs included in the operative report should not be used alone to hold the surgeon liable.

Rehabilitation versus surgical reconstruction for non-acute anterior cruciate ligament injury (ACL SNNAP): a pragmatic randomised controlled trial.

BACKGROUND: Anterior cruciate ligament (ACL) rupture is a common debilitating injury that can cause instability of the knee. We aimed to investigate the best management strategy between reconstructive surgery and non-surgical treatment for patients with a non-acute ACL injury and persistent symptoms of instability. METHODS: We did a pragmatic, multicentre, superiority, randomised controlled trial in 29 secondary care National Health Service orthopaedic units in the UK. Patients with symptomatic knee problems (instability) consistent with an ACL injury were eligible. We excluded patients with meniscal pathology with characteristics that indicate immediate surgery. Patients were randomly assigned (1:1) by computer to either surgery (reconstruction) or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment), stratified by site and baseline Knee Injury and Osteoarthritis Outcome Score-4 domain version (KOOS4). This management design represented normal practice. The primary outcome was KOOS4 at 18 months after randomisation. The principal analyses were intention-to-treat based, with KOOS4 results analysed using linear regression. This trial is registered with ISRCTN, ISRCTN10110685, and ClinicalTrials.gov, NCT02980367. FINDINGS: Between Feb 1, 2017, and April 12, 2020, we recruited 316 patients. 156 (49%) participants were randomly assigned to the surgical reconstruction group and 160 (51%) to the rehabilitation group. Mean KOOS4 at 18 months was 73·0 (SD 18·3) in the surgical group and 64·6 (21·6) in the rehabilitation group. The adjusted mean difference was 7·9 (95% CI 2·5-13·2; p=0·0053) in favour of surgical management. 65 (41%) of 160 patients allocated to rehabilitation underwent subsequent surgery according to protocol within 18 months. 43 (28%) of 156 patients allocated to surgery did not receive their allocated treatment. We found no differences between groups in the proportion of intervention-related complications. INTERPRETATION: Surgical reconstruction as a management strategy for patients with non-acute ACL injury with persistent symptoms of instability was clinically superior and more cost-effective in comparison with rehabilitation management. FUNDING: The UK National Institute for Health Research Health Technology Assessment Programme.

Are Neighborhood Conditions Associated With Surgical Delays and Meniscus Tears in Children and Adolescents Undergoing ACL Reconstruction?

BACKGROUND: Markers of a patient's social determinants of health, including healthcare insurance and median household income based on ZIP Code, have been associated with the interval between injury and ACL reconstruction (ACLR) as well as the presence of concomitant meniscus tears in children and adolescents. However, the aforementioned surrogate indicators of a patient's social determinants of health may not reflect all socioeconomic and healthcare resources affecting the care of ACL injuries in children and adolescents. The use of multivariate indices such as the Child Opportunity Index (COI) may help to better identify patients at risk for increased risk for delay between ACL injury and surgery, as well as the incidence of meniscus tears at the time of surgery. The COI is a summative measure of 29 indicators that reflect neighborhood opportunities across three domains: education, health and environment, and social and economic factors. COI scores range from 0 to 100 (100 being the highest possible score), as well as five categorical scores (very low, low, moderate, high, and very high) based on quintile rankings. QUESTIONS/PURPOSES: To investigate the relationship between neighborhood conditions and the treatment of ACL injuries in children and adolescents via the COI, we asked: (1) Is a lower COI score associated with a longer delay between ACL injury and surgery? (2) Does a higher proportion of patients with lower COI scores have meniscus tears at the time of ACLR? METHODS: In this retrospective, comparative study, we considered data from 565 patients, 18 years or younger, who underwent primary ACLR at an urban, tertiary children's hospital between 2011 and 2021. Of these patients, 5% (31 of 565) did not have a clearly documented date of injury, 2% (11 of 565) underwent revision reconstructions, and 1% (5 of 565) underwent intentionally delayed or staged procedures. Because we specifically sought to compare patients who had low or very low COI scores (lowest two quintiles) with those who had high or very high scores (highest two quintiles), we excluded 18% (103 of 565) of patients with moderate scores. Ultimately, 73% (415 of 565) of patients with COI scores in either the top or bottom two quintiles were included. Patient addresses at the time of surgery were used to determine the COI score. There were no differences between the groups in terms of gender. However, patients with high or very high COI scores had a lower median (IQR) age (15 years [2.6] versus 17 years [1.8]; p < 0.001) and BMI (23 kg/m 2 [6.1] versus 25 kg/m 2 [8.8]; p < 0.001), were more commonly privately insured (62% [117 of 188] versus 22% [51 of 227]; p < 0.001), and had a higher proportion of patients identifying as White (67% [126 of 188] versus 6.2% [14 of 227]; p < 0.001) compared with patients with low or very low COI scores. Medical records were reviewed for demographic, preoperative, and intraoperative data. Univariate analyses focused on the relationship of the COI and interval between injury and surgery, frequency of concomitant meniscus tears, and frequency of irreparable meniscus tears treated with partial meniscectomy. Multivariable regression analyses were used to determine factors that were independently associated with delayed surgery (longer than 60 and 90 days after injury), presence of concomitant meniscal injuries, and performance of meniscectomy. Multivariable models included insurance and race or ethnicity to determine whether COI was independently associative after accounting for these variables. RESULTS: Patients with a high or very high COI score had surgery earlier than those with a low or very low COI score (median [IQR] 53 days [53] versus 97 days [104]; p < 0.001). After adjusting for insurance and race/ethnicity, we found that patients with a low or very low COI score were more likely than patients with a high or very high COI score to have surgery more than 60 days after injury (OR 2.1 [95% CI 1.1 to 4.0]; p = 0.02) or more than 90 days after injury (OR 1.8 [95% CI 1.1 to 3.4]; p = 0.04). Furthermore, patients with low or very low COI scores were more likely to have concomitant meniscus tears (OR 1.6 [95% CI 1.1 to 2.5]; p = 0.04) compared with patients with high or very high COI scores. After controlling for insurance, race/ethnicity, time to surgery, and other variables, there was no association between COI and meniscectomy (OR 1.6 [95% CI 0.9 to 2.8]; p = 0.12) or presence of a chondral injury (OR 1.7 [95% CI 0.7 to 3.9]; p = 0.20). CONCLUSION: As the COI score is independently associated with a delay between ACL injury and surgery as well as the incidence of meniscus tears at the time of surgery, this score can be useful in identifying patients and communities at risk for disparate care after ACL injury. The COI score or similar metrics can be incorporated into medical records to identify at-risk patients and dedicate appropriate resources for efficient care. Additionally, neighborhoods with a low COI score may benefit from improvements in the availability of additional and/or improved resources. Future studies should focus on the relationship between the COI score and long-term patient-reported functional outcomes after ACL injury, identification of the specific timepoints in care that lead to delayed surgery for those with lower COI scores, and the impact of community-based interventions in improving health equity in children with ACL injury. LEVEL OF EVIDENCE: Level III, therapeutic study.

Is Preferred Language Other Than English Associated With Delayed Surgery After ACL Injury in Children and Adolescents?

BACKGROUND: Previous studies have investigated the impact of social determinants of health, such as the type of healthcare insurance and household income, on children and adolescents with ACL tears. However, despite the increasing incidence of ACL injury in young patients and a substantial proportion of families who may prefer languages other than English, the relationship between language and clinical care remains unclear. QUESTIONS/PURPOSES: To investigate the relationship between language and the care of children and adolescents with ACL tears, we asked: (1) Is a preferred language other than English (PLOE) associated with a delay between ACL injury and surgery? (2) Is a PLOE associated with a greater odds of a patient experiencing a meniscal tear and undergoing a meniscectomy than in those who prefer English? METHODS: We treated 591 patients surgically for ACL injuries between 2011 and 2021. Of those, we considered patients aged 18 years or younger who underwent primary ACL reconstruction for this retrospective, comparative study. Five percent (31 of 591) of patients were excluded because the date of injury was not clearly documented, 2% (11 of 591) were revision reconstructions, and 1% (6 of 591) underwent procedures that were intentionally delayed or staged, leaving 92% (543 of 591) for analysis. The mean age was 16 ± 2 years, and 51% (276 of 543) of patients were boys. The family's preferred language was noted, as were demographic data, time between injury and surgery, and intraoperative findings. A language other than English was preferred by 21% (113 of 543) of patients. Of these, 94% (106 of 113) preferred Spanish. In a univariate analysis, we used independent-samples t-tests, Mann-Whitney U-tests, and Fisher exact tests, as appropriate. Purposeful-entry multivariable regression analyses were used to determine whether PLOE was associated with increased time to surgery, concomitant meniscus injury, or performance of meniscectomy while adjusting for confounding variables. Variables were included in multivariable models if they met the threshold for statistical significance in univariate testing (p < 0.05). RESULTS: The median time between injury and ACL reconstruction was shorter in families who preferred English compared with those with a PLOE (69 days [IQR 80] versus 103 days [IQR 107)]; p < 0.001). After controlling for potentially confounding variables like insurance and age, we found that patients whose families had a PLOE had greater odds of undergoing surgery more than 60 days after injury (OR 2.2 [95% CI 1.3 to 3.8]; p = 0.005) and more than 90 days after injury (OR 1.8 [95% CI 1.1 to 2.8]; p = 0.02). After controlling for insurance, age, and other factors, PLOE was not associated with surgical delay beyond 180 days, concomitant meniscal tears, or performance of meniscectomy. CONCLUSION: In this study of children and adolescents undergoing primary ACL reconstruction, patients whose families prefer a language other than English experienced a longer delay between injury and surgery. In areas with a large proportion of families with a PLOE, partnerships with primary care clinicians, emergency departments, schools, athletic teams, and community organizations may improve efficiency in the care of children with ACL injuries. Clinicians proficient in other languages, reliable interpreter services, and translated references and resources may also be impactful. Our results suggest a need for further research on the experiences, needs, and long-term outcomes of these patients, as well as the association of preferred language with results after surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

Differences in postoperative knee function based on concomitant treatment of lateral meniscal injury in the setting of primary ACL reconstruction.

BACKGROUND: Concomitant lateral meniscal (LM) injuries are common in acute anterior cruciate ligament (ACL) ruptures. However, the effect of addressing these injuries with various treatment methods during primary ACL reconstruction (ACLR) on patient-reported outcomes (PROs) is unknown. Therefore, the purpose of this study was to compare postoperative Knee injury and Osteoarthritis Outcome Score (KOOS) at 2-, 5-, and 10-years after isolated primary ACLR to primary ACLR with various treatment methods to address concomitant LM injury. METHODS: This study was based on data from the Swedish National Knee Ligament Registry. Patients ≥ 15 years with data on postoperative KOOS who underwent primary ACLR between the years 2005 and 2018 were included in this study. The study population was divided into five groups: 1) Isolated ACLR, 2) ACLR + LM repair, 3) ACLR + LM resection, 4) ACLR + LM injury left in situ, and 5) ACLR + LM repair + LM resection. Patients with concomitant medial meniscal or other surgically treated ligament injuries were excluded. RESULTS: Of 31,819 included patients, 24% had LM injury. After post hoc comparisons, significantly lower scores were found for the KOOS Symptoms subscale in ACLR + LM repair group compared to isolated ACLR (76.0 vs 78.3, p = 0.0097) and ACLR + LM injury left in situ groups (76.0 vs 78.3, p = 0.041) at 2-year follow-up. However, at 10-year follow-up, no differences were found between ACLR + LM repair and isolated ACLR, but ACLR + LM resection resulted in significantly lower KOOS Symptoms scores compared to isolated ACLR (80.4 vs 82.3, p = 0.041). CONCLUSION: The results of this study suggest that LM injury during ACLR is associated with lower KOOS scores, particularly in the Symptoms subscale, at short- and long-term follow-up. However, this finding falls below minimal clinical important difference and therefore may not be clinically relevant. LEVEL OF EVIDENCE: III.

Operative Management for Anterior Cruciate Ligament Injury in Patients Over 40 Years Old Yields Increased Clinical Outcome: A Systematic Review.

PURPOSE: To evaluate outcomes of anterior cruciate ligament (ACL) rupture in patients ≥40 years treated nonoperatively or with ACL reconstruction (ACLR). METHODS: A review of MEDLINE, CINAHL, SportDiscus, Embase, Web of Science, and Cochrane databases from inception to June 1, 2021, was performed to identify randomized controlled trials, prospective or retrospective cohorts, case controls, or case series that met the following criteria: English-language studies reporting at least one subjective and/or objective outcome measure in ACL rupture patients ≥40 years treated nonoperatively or by ACLR. No limits were placed on graft type, time-to-surgery/follow-up, or concomitant procedures. Variability in patient-reported outcome scores, including subjective IKDC score, Lysholm score, Tegner activity score, and Knee Injury and Osteoarthritis Outcome Score, was assessed to evaluate the utility of applying previously established clinically meaningful thresholds to pooled outcome data. RESULTS: 12,605 citations were identified using screening criteria. Sixty studies satisfied criteria following full-text review. As previous systematic reviews reported on earlier literature evaluating ACLR outcomes in patients ≥40 years, studies in this review were limited to include only those published in the last 10 years (40 studies). An additional 16 studies were excluded based on aims of the review not identified during initial screen. Although preoperative to postoperative population-based improvements in Lysholm score, Tegner score, and IKDC score surpassed minimal clinically important differences (MCID) in at least 50% of studies, the variability present in the pooled data may limit its application. No studies evaluated nonoperative outcomes. CONCLUSIONS: Evidence supports operative management in patients ≥40 years, as studies generally demonstrated preoperative to postoperative improvements in clinical outcomes based on population-level changes. However, application of patient-level clinically relevant thresholds to pooled outcome data should be undertaken with caution as reporting of population-based outcome scores may not accurately reflect changes in individual patients. LEVEL OF EVIDENCE: Systematic review, IV.

Identifying modifiable risk factors and screening strategies associated with anterior cruciate ligament injury risk in children aged 6 to 13 years: A systematic review.

Growing anterior cruciate ligament (ACL) injury incidence is reported in countries across Europe, North America and in Australia for 5-14-year-olds, yet research on injury risk reduction predominantly focuses on populations aged > 13 years. For injury risk reduction, it is crucial to understand (i) which modifiable risk factors are associated with ACL injury in children (6-13 years) and (ii) how these risk factors are assessed. Articles were grouped according to sex/gender and/or maturational/age differences and examined modifiable risk factors during different physical screening tasks. The included articles (n = 40) predominantly examined intrinsic risk factors in girls aged 10-13 years. Factors mechanically linked to increased ACL loading at this age included increased peak knee adductor moments, knee valgus angles, hip and knee extension, and ground reaction forces. Assessment focused on laboratory-based assessments (e.g., motion capture, force plates). This review concluded that modifiable risk factors are present in children aged 6-13 years and that injury risk reduction strategies should be implemented as early as possible regardless of sex/gender. Further, screening strategies need updating to be childhood specific and feasible for the wide community. Additional research on extrinsic risk factors, norm values and children aged 6-9 years could allow for more targeted risk reduction strategies.

Increasing rates of ACL injuries in children aged 5 to 14 years are reported in countries across Europe, North America and in AustraliaResearch on modifiable risk factors focuses on internal risk factors in children aged 10-13 years and neglects external risk factors as well as younger children (6-10 years)Screening strategies to determine risk of ACL injury risk in children are laboratory based as opposed to cost-effective and quicker-to-analyse in-field assessmentResearch is warranted to examine external risk factors and in-field screening strategies in childhood.

BLU-DAT: a new reliable and accurate arthrometer for measuring anterior knee laxity.

PURPOSE: Although many arthrometers have been developed to assess anterior knee laxity, reliability and diagnostic accuracy of these devices are still debated. The aim of the present study was to evaluate the validity of a new arthrometer in the outpatient setting, with the hypothesis that it had good validity in terms of reliability and diagnostic accuracy. METHODS: Seventy-eight subjects (39 with ACL injury and 39 with normal ACL) were tested. ATT was assessed by means of the Lachman test at 30° of flexion with a new testing device (BLU-DAT) under three different loading conditions: 7 kg (69 N), 9 kg (88 N) and maximum (MMT). The tests were performed on both knees to obtain SSD. In the ACL injury group, the tests were performed by two examiners and one of them repeated a second test series. Inter- and intra-observer reliability were assessed with the intraclass correlation coefficients (ICCs) for the average SSD measures. In the normal-ACL group, the analysis was performed with the same testing setup. Side-to-side difference measures of the two groups at every loading condition were compared by Student's t test. Data of test series were dichotomized based on the threshold value of 3-mm SSD as pathological ATT and 2 × 2 contingency tables were used to assess diagnostic accuracy. RESULTS: The ICCs for intra-observer reliability at 7-kg (69 N), 9-kg (88 N) and MMT measurements were 0.781, 0.855 and 0.913, respectively. The ICC for inter-observer reliability at 7-kg (69 N), 9-kg (88 N) and MMT measurements were 0.701, 0.845 and 0.834, respectively. Comparison between the two groups showed a significant mean difference ranging from 3.4 mm for 7-kg (69 N) load to 4.6 mm for MMT. Overall accuracy ranged from 84.6% for 7-kg load to 98.7% for MMT. CONCLUSION: The BLU-DAT has proven to be an instrument with good intra- and inter-observer reliability and very good accuracy in the diagnosis of ACL injuries in the outpatient setting. So, the BLU-DAT can be a new useful tool in everyday clinical practice to assist in the diagnosis of ACL injury. LEVEL OF EVIDENCE: II.

Management of anterior cruciate ligament revision in adults: the 2022 ESSKA consensus: part II-surgical strategy.

PURPOSE: The aim of this ESSKA consensus is to give recommendations based on scientific evidence and expert opinion to improve the diagnosis, preoperative planning, indication and surgical strategy in Anterior Cruciate Ligament revision. METHODS: Part 2, presented herein, followed exactly the same methodology as Part 1: the so-called ESSKA formal consensus derived from the Delphi method. Eighteen questions were ultimately asked. The quality of the answers received the following grades of recommendation: Grade A (high level scientific support), Grade B (scientific presumption), Grade C (low level scientific support) or Grade D (expert opinion). All answers were scored from 1 to 9 by the raters. Once a general consensus had been reached between the steering and rating groups, the question-answer sets were submitted to the peer-review group. A final combined meeting of all the members of the consensus was then held to ratify the document. RESULTS: The review of the literature revealed a rather low scientific quality of studies examining the surgical strategy in cases of ACL reconstruction failure. Of the 18 questions, only 1 received a Grade A rating; 5, a Grade B rating; and 9, grades of C or D. The three remaining complex questions received further evaluations for each portion of the question and were looked at in more detail for the following grades: B and D; A, C and D; or A, B, C and D. The mean rating of all questions by the rating group was 8.0 + - 1.1. The questions and recommendations are listed in the article. CONCLUSION: ACL revision surgery, especially the surgical strategy, is a widely debated subject with many different opinions and techniques. The literature reveals a poor level of standardization. Therefore, this international European consensus project is of great importance and clinical relevance for guiding the management of ACL revision in adults. LEVEL OF EVIDENCE: Level II.

Machine learning can accurately predict risk factors for all-cause reoperation after ACLR: creating a clinical tool to improve patient counseling and outcomes.

PURPOSE: Identifying predictive factors for all-cause reoperation after anterior cruciate ligament reconstruction could inform clinical decision making and improve risk mitigation. The primary purposes of this study are to (1) determine the incidence of all-cause reoperation after anterior cruciate ligament reconstruction, (2) identify predictors of reoperation after anterior cruciate ligament reconstruction using machine learning methodology, and (3) compare the predictive capacity of the machine learning methods to that of traditional logistic regression. METHODS: A longitudinal geographical database was utilized to identify patients with a diagnosis of new anterior cruciate ligament injury. Eight machine learning models were appraised on their ability to predict all-cause reoperation after anterior cruciate ligament reconstruction. Model performance was evaluated via area under the receiver operating characteristics curve. To explore modeling interpretability and radiomic feature influence on the predictions, we utilized a game-theory-based method through SHapley Additive exPlanations. RESULTS: A total of 1400 patients underwent anterior cruciate ligament reconstruction with a mean postoperative follow-up of 9 years. Two-hundred and eighteen (16%) patients experienced a reoperation after anterior cruciate ligament reconstruction, of which 6% of these were revision ACL reconstruction. SHapley Additive exPlanations plots identified the following risk factors as predictive for all-cause reoperation: diagnosis of systemic inflammatory disease, distal tear location, concomitant medial collateral ligament repair, higher visual analog scale pain score prior to surgery, hamstring autograft, tibial fixation via radial expansion device, younger age at initial injury, and concomitant meniscal repair. Pertinent negatives, when compared to previous studies, included sex and timing of surgery. XGBoost was the best-performing model (area under the receiver operating characteristics curve of 0.77) and outperformed logistic regression in this regard. CONCLUSIONS: All-cause reoperation after anterior cruciate ligament reconstruction occurred at a rate of 16%. Machine learning models outperformed traditional statistics and identified diagnosis of systemic inflammatory disease, distal tear location, concomitant medial collateral ligament repair, higher visual analog scale pain score prior to surgery, hamstring autograft, tibial fixation via radial expansion device, younger age at initial injury, and concomitant meniscal repair as predictive risk factors for reoperation. Pertinent negatives, when compared to previous studies, included sex and timing of surgery. These models will allow surgeons to tabulate individualized risk for future reoperation for patients undergoing anterior cruciate ligament reconstruction. LEVEL OF EVIDENCE: III.

No correlation between performance tests, clinical measurements and data from patient-reported outcome measures (PROM) in children reconstructed for anterior cruciate ligament injury.

PURPOSE: To investigate if patient-reported outcome measures (PROMs), functional tests and clinical measures correlate well in children after reconstruction of the anterior cruciate ligament (ACL). It was hypothesized that these outcomes correlate, so it is sufficient to report only one of them. METHODS: A consecutive group of children (< 16 years old) who had an ACL reconstruction, were prospectively followed and assessed after 1-year with Pedi-IKDC and KOOS-Child, instrumented laxity measurement, range of motion, extension strength and four performance tests. Relations between the different outcomes were calculated by partial correlation coefficient analysis, controlling for gender, age, height, and weight. RESULTS: Outcomes were available for 141 of 163 children. There were only few positive and weak correlations between performance tests and PROM scores and between clinical measurements and PROM scores. There were weak to strong correlations between the scores from Pedi-IKDC and the scores from each of the five domains of KOOS-Child and a weak to moderate correlation between the different domains of KOOS-Child. Similar correlations were found between the different performance tests. CONCLUSION: For children who had their ACL reconstructed there was no clinically important correlation between scores obtained by PROMs, a battery of functional performance tests and instrumented laxity of the knee at 1-year follow-up. This is an argument for always to include and report all three types of outcomes. LEVEL OF EVIDENCE: Level II.

Functional performance tests, clinical measurements, and patient-reported outcome measures do not correlate as outcomes 1 year after anterior cruciate ligament reconstruction.

PURPOSE: The results after anterior cruciate ligament reconstruction (ACLR) are evaluated by laxity measures, functional tests, and patients' perception by patient-reported outcome measures (PROMs). It is not known, if one of these evaluation instruments is representative or if outcome scores from all must be reported to obtain a full evaluation of the condition. The aim was to study the correlations between these three types of outcomes 1 year after primary ACLR. METHOD: All adult patients (range 18-45 years) who had an ACLR between 1.1.2019 and 31.12.2021 were offered 1-year follow-up by an independent observer. Preoperative information about knee laxity and peroperative information about the condition of menisci and cartilage were registered. At 1-year follow-up clinical and instrumented knee stability and function assessed by four different hop tests were registered. Patients completed four PROMs (the Subjective International Knee Documentation Committee (IKDC) score, the Knee Numeric-Entity Evaluation Score (KNEES-ACL), the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Lysholm score) and Tegner activity scale and answered anchor questions regarding satisfaction and willingness to repeat the operation. RESULTS: A total of 190 adults attended the 1-year follow-up and 151 had all assessments. There were only a few positive and weak correlations between performance tests and PROMS and between clinical measurements and PROMS (r = 0.00-0.38), and the majority were of negligible strength. Tegner score had in general the highest correlation (low to moderate). The highest correlation was 0.53 (moderate) between the anchor question about patient satisfaction and Lysholm/IKDC scores. There was no difference in the correlations depending on meniscal condition. CONCLUSIONS: In ACLR patients there was no clinically relevant correlation between scores obtained by PROMs, a battery of functional performance tests and instrumented laxity of the knee at 1-year follow-up. Therefore, one type of outcome cannot represent the others. This is an argument for always to include and report all three types of outcomes, and conclusions based on one type of outcome may not be sufficient. LEVEL OF EVIDENCE: II.

Different patient and activity-related characteristics result in different injury profiles for patients with anterior cruciate ligament and posterior cruciate ligament injuries.

PURPOSE: To compare patient characteristics including patient sex, age, body mass index (BMI), activities at the time of injury and injury profiles in patients with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries. METHODS: Data were obtained from the Swedish National Knee Ligament Registry. Two study groups were created: (1) index ACL reconstruction (ACL group) and (2) index PCL reconstruction (PCL group). Between-group differences were investigated using Fisher's exact test and Fisher's non-parametric permutation test for dichotomous variables and continuous variables, respectively. RESULTS: Of 39,010 patients, 38,904 were ACL injuries. A larger proportion of patients with combined injuries to the PCL, meniscus and cartilage were female, aged > 25 years and with a BMI of > 35 kg/m2 compared with patients with combined injuries to the ACL, meniscus and cartilage. An isolated ACL injury was more commonly found in males, while all other injury profiles of ACL, including combined injuries with meniscus, cartilage and collateral ligament injuries, were more frequently observed in females. The PCL injuries were sustained either during pivoting sports, non-pivoting sports or were traffic-related. CONCLUSION: Different patient characteristics (BMI, age and sex), and activities at the time of injury (sport- versus traffic-related activities), resulted in distinct injury profiles for the ACL and PCL groups. These findings provide valuable information of the way specific injury patterns of cruciate ligament injuries occur, and subsequently may help clinicians with the diagnostic process of ACL and PCL injuries. LEVEL OF EVIDENCE: III.

Risk factors for secondary meniscus tears can be accurately predicted through machine learning, creating a resource for patient education and intervention.

PURPOSE: This study sought to develop and internally validate a machine learning model to identify risk factors and quantify overall risk of secondary meniscus injury in a longitudinal cohort after primary ACL reconstruction (ACLR). METHODS: Patients with new ACL injury between 1990 and 2016 with minimum 2-year follow-up were identified. Records were extensively reviewed to extract demographic, treatment, and diagnosis of new meniscus injury following ACLR. Four candidate machine learning algorithms were evaluated to predict secondary meniscus tears. Performance was assessed through discrimination using area under the receiver operating characteristics curve (AUROC), calibration, and decision curve analysis; interpretability was enhanced utilizing global variable importance plots and partial dependence curves. RESULTS: A total of 1187 patients underwent ACLR; 139 (11.7%) experienced a secondary meniscus tear at a mean time of 65 months post-op. The best performing model for predicting secondary meniscus tear was the random forest (AUROC = 0.790, 95% CI: 0.785-0.795; calibration intercept = 0.006, 95% CI: 0.005-0.007, calibration slope = 0.961 95% CI: 0.956-0.965, Brier's score = 0.10 95% CI: 0.09-0.12), and all four machine learning algorithms outperformed traditional logistic regression. The following risk factors were identified: shorter time to return to sport (RTS), lower VAS at injury, increased time from injury to surgery, older age at injury, and proximal ACL tear. CONCLUSION: Machine learning models outperformed traditional prediction models and identified multiple risk factors for secondary meniscus tears after ACLR. Following careful external validation, these models can be deployed to provide real-time quantifiable risk for counseling and timely intervention to help guide patient expectations and possibly improve clinical outcomes. LEVEL OF EVIDENCE: III.

The anterior cruciate ligament injury severity scale (ACLISS) is an effective tool to document and categorize the magnitude of associated tissue damage in knees after primary ACL injury and reconstruction.

PURPOSE: To develop a tool allowing to classify the magnitude of structural tissue damage occurring in ACL injured knees. The proposed ACL Injury Severity Scale (ACLISS) would provide an easy description and categorization of the wide spectrum of injuries in patients undergoing primary ACL reconstruction, reaching from isolated ACL tears to ACL injuries with a complex association of combined structural damage. METHODS: A stepwise approach was used to develop the ACLISS. The eligibility of each item was based on a literature search and a consensus between the authors after considering the diagnostic modalities and clinical importance of associated injuries to the menisci, subchondral bone, articular cartilage or collateral ligaments. Then, a retrospective analysis of associated injuries was performed in 100 patients who underwent a primary ACL reconstruction (ACLR) by a single surgeon. This was based on acute preoperative MRI (within 8 weeks after injury) as well as intraoperative arthroscopic findings. Depending on their prevalence, the number of selected items was reduced. Finally, an analysis of the overall scale distribution was performed to classify the patients according to different injury profiles. RESULTS: A final scoring system of 12 points was developed (12 = highest severity). Six points were attributed to the medial and lateral tibiofemoral compartment respectively. The amount of associated injuries increased with ACLISS grading. The median scale value was 4.5 (lower quartile 3.0; higher quartile 7.0). Based on these quartiles, a score < 4 was considered to be an injury of mild severity (grade I), a score between ≥ 4 and ≤ 7 was defined as moderately severe (grade II) and a score > 7 displayed the most severe cases of ACL injuries (grade III). The knees were graded ACLISS I in 35%, ACLISS II in 49% and ACLISS III in 16% of patients. Overall, damage to the lateral tibiofemoral compartment was predominant (p < 0.01), but a proportional increase of tissue damage could be observed in the medial tibiofemoral compartment with the severity of ACLISS grading (p < 0.01). CONCLUSIONS: The ACLISS allowed to easily and rapidly identify different injury severity profiles in patients who underwent primary ACLR. Injury severity was associated with an increased involvement of the medial tibiofemoral compartment. The ACLISS is convenient to use in daily clinical practice and represents a feasible grading and documentation tool for a reproducible comparison of clinical data in ACL injured patients. LEVEL OF EVIDENCE: Level III.

Fear of reinjury following primary anterior cruciate ligament reconstruction: a systematic review.

PURPOSE: This review aims to elucidate the most commonly reported method to quantify fear of reinjury or kinesiophobia and to identify key variables that influence the degree of kinesiophobia following primary anterior cruciate ligament reconstruction (ACLR). METHODS: A systematic search across three databases (Pubmed, Ovid (MEDLINE), and EMBASE) was conducted from database inception to August 7th, 2022. The authors adhered to the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. Quality assessment of the included studies was conducted according to the Methodological Index for Non-Randomized Studies (MINORS) criteria. RESULTS: Twenty-six studies satisfied the inclusion criteria and resulted in 2,213 total patients with a mean age of 27.6 years and a mean follow-up time of 36.7 months post-surgery. The mean MINORS score of the included studies was 11 out of 16 for non-comparative studies and 18 out of 24 for comparative studies. Eighty-eight percent of included studies used variations of the Tampa Scale of Kinesiophobia (TSK) to quantify kinesiophobia and 27.0% used Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI). The results of this study shows a common association between higher kinesiophobia and poor patient-reported functional status measured using International Knee Documentation Committee (IKDC) Scores, Activity of Daily Living (ADL), Quality of Life (QOL), and Sports/Recreation (S/R) subscales of Knee Osteoarthritis and Outcome Score (KOOS) and Lysholm scores. Postoperative symptoms and pain catastrophizing measured using the KOOS pain and symptom subscales and Pain Catastrophizing Score (PCS) also influenced the degree of kinesiophobia following ACLR. Patients with an increased injury to surgery time and being closer to the date of surgery postoperatively demonstrated higher levels of kinesiophobia. Less common variables included being a female patient, low preoperative and postoperative activity status and low self-efficacy. CONCLUSION: The most common methods used to report kinesiophobia following primary ACLR were variations of the TSK scale followed by ACL-RSI. The most commonly reported factors influencing higher kinesiophobia in this patient population include lower patient-reported functional status, more severe postoperative symptoms such as pain, increased injury to surgery time, and being closer to the date of surgery postoperatively. Kinesiophobia following primary ACLR is a critical element affecting post-surgical outcomes, and screening should be implemented postoperatively to potentially treat in rehabilitation and recovery. LEVEL OF EVIDENCE: IV.

Posterior tibial plateau impaction fractures are not associated with increased knee instability: a quantitative pivot shift analysis.

PURPOSE: This study aimed to evaluate posterolateral tibial plateau impaction fractures and how they contribute to rotatory knee laxity using quantitative pivot shift analysis. It was hypothesised that neither the presence of nor the degree of involvement of the plateau would affect rotatory knee laxity in the ACL-deficient knee. METHODS: A retrospective review of prospectively collected data on 284 patients with complete anterior cruciate ligament (ACL) injuries was conducted. Posterolateral tibial plateau impaction fractures were identified on preoperative MRI. The patients were divided into two cohorts: "fractures" or "no fractures". The cohort with fractures was further categorised based on fracture morphology: "extra-articular", "articular-impaction", or "displaced-articular fragment". All data were collected during examination under anaesthesia performed immediately prior to ACL reconstruction. This included a standard pivot shift test graded by the examiner and quantitative data including anterior tibial translation (mm) via Rolimeter, quantitative pivot shift (QPS) examination (mm) via PIVOT tablet technology, and acceleration (m/sec2) during the pivot shift test via accelerometer. Quantitative examinations were compared with the contralateral knee. RESULTS: There were 112 patients with posterolateral tibial plateau impaction fractures (112/284, 39%). Of these, 71/112 (63%) were "extra-articular", 28/112 (25%) "articular-impaction", and 13/112 (12%) "displaced-articular". Regarding the two groups with or without fractures, there was no difference in subjective pivot shift (2 ± 0 vs 2 ± 0, respectively, n.s.), QPS (2.4 ± 1.6 mm vs 2.7 ± 2.2 mm, respectively, n.s.), anterior tibial translation measurements (6 ± 3 mm vs 5 ± 3 mm, respectively, n.s.), or acceleration of the knee during the pivot (1.7 ± 2.3 m/s2 vs 1.8 ± 3.1 m/s2, respectively, n.s.). When the fractures were further subdivided, subgroup analysis revealed no significant differences noted in any of the measured examinations between the fracture subtypes. CONCLUSION: This study showed that the posterolateral tibial plateau impaction fractures are commonly encountered in the setting of ACL tears; however, contrary to previous reports, they do not significantly increase rotatory knee laxity. This suggests that this type of concomitant injury may not need to be addressed at the time of ACL reconstruction. LEVEL OF EVIDENCE: Level III.

The posterior cruciate ligament index as a reliable indirect sign of anterior cruciate ligament rupture is associated with the course of knee joint injury.

PURPOSE: The objective of this study was to clarify the clinical value of the posterior cruciate ligament index (PCLI) in anterior cruciate ligament (ACL) rupture, to explore the relationship between the PCLI and course of disease, and to identify the influencing factors of the PCLI. METHODS: The PCLI was defined a quotient of the X (the tibial and femoral PCL attachments) and the Y (the maximum perpendicular distance from X to the PCL). A total of 858 patients were enrolled in this case-control study, including 433 patients with ACL ruptures who were assigned to the experimental group and 425 patients with meniscal tears (MTs) who were allocated to the control group. Some patients in the experimental group have collateral ligament rupture (CLR). Information, such as the patient's age, sex, and course of disease, was recorded. All patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The PCLI and the depth of the lateral femoral notch sign (LFNS) were calculated based on the MRI findings, and the characteristics of the PCLI were explored. RESULTS: The PCLI in the experimental group (5.1 ± 1.6) was significantly smaller than that in the control group (5.8 ± 1.6) (P < 0.05). The PCLI gradually decreased with time and was only 4.8 ± 1.4 in patients in the chronic phase (P < 0.05). This change was not due to the decrease in X but rather the increase in Y. The results also showed that the PCLI was not related to the depth of the LFNS or injuries of other structures in the knee joint. Furthermore, when the optimal cut-off point of the PCLI was 5.2 (area under the curve = 71%), the specificity and the sensitivity were 84% and 67%, respectively, but the Youden index was just 0.3 (P < 0.05). CONCLUSION: The PCLI decreases due to the increase in Y instead of the decrease in X with time, especially in the chronic phase. The change in X in this process may be offset during imaging. In addition, there are fewer influencing factors that lead to changes in the PCLI. Therefore, it can be used as a reliable indirect sign of ACL rupture. However, it is difficult to quantify the diagnostic criteria of the PCLI in clinical practice. Thus, the PCLI as a reliable indirect sign of ACL rupture is associated with the course of knee joint injury, and it can be used to describe the instability of the knee joint. LEVELS OF EVIDENCE: III.

Evaluation of the accuracy and intra- and interobserver reliability of three manual laxity tests for canine cranial cruciate ligament rupture-An ex vivo kinetic and kinematic study.

OBJECTIVES: To investigate the accuracy and intra- and interobserver reliability of the cranial drawer test (CD), tibial compression test (TCT), and the new tibial pivot compression test (TPCT) in an experimental setting resembling acute cranial cruciate ligament rupture (CCLR) and to elucidate the ability to subjectively estimate cranial tibial translation (CTT) during testing. STUDY DESIGN: Experimental ex vivo study. SAMPLE POPULATION: Ten cadaveric hindlimbs of large dogs. METHODS: Kinetic and 3D-kinematic data was collected while three observers performed the tests on each specimen with intact (INTACT) and transected cranial cruciate ligament (CCLD) and compared using three-way repeated-measures ANOVA. Subjectively estimated CTT (SCTT), obtained during a separate round of testing, was compared to kinematic data by Pearson correlation. RESULTS: CTT was significantly higher for CCLD than for INTACT for all tests, resulting in 100% sensitivity and specificity. TPCT induced the highest CTT and internal rotation. Intra- and interobserver agreement of translation was excellent. For rotation and kinetics, agreement was more variable. SCTT strongly correlated with the objectively measured values. CONCLUSION: The CD, TCT and the new TPCT were all accurate and reliable. The high translations and rotations during TPCT are promising, encouraging further development of this test. SCTT was reliable in our experimental setting. CLINICAL SIGNIFICANCE: Veterinary manual laxity tests are accurate and reliable in acute CCLR. The TPCT might have potential for the assessment of subtle and rotational canine stifle instabilities. The high reliability of SCTT implies that grading schemes for stifle laxity, similar to human medicine, could be developed.