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Anterior Cruciate Ligament

ACL deficiency and instability — non-operative management vs reconstruction, graft selection, and criteria for return to sport.

Overview

Successful anterior cruciate ligament reconstruction requires definition across four equally important categories: early adverse events, patient-reported outcomes, ACL graft failure/recurrent ligament disruption, and clinical measures of knee function and structure [1]. An evidence-based approach integrates best available research with clinical expertise and patient values, emphasizing appropriately powered expertise-based trials and best-practice rehabilitation protocols to optimize outcomes [78].

Anterior cruciate ligament reconstruction is justified in patients over 40 years old with persisting subjective symptomatic anterior knee instability, with indications based on individual factors rather than age [11]. Male sex, younger age, lower body mass index, athletes, shorter time from injury to surgery, and non-contact injury are associated with achieving the thresholds for substantial clinical benefit for patient-reported outcome measures after primary anterior cruciate ligament reconstruction [82]. When clinical indications exist, simultaneous bilateral anterior cruciate ligament reconstruction is recommended as a safe, effective, and cost-effective option compared to staged procedures [81].

There were few or no differences in subjective and objective outcomes related to timing of anterior cruciate ligament reconstruction [2]. More extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction [17]. Prospective studies with sufficient follow-up comparing the outcomes and failure rates of ACL repair versus reconstruction are needed prior to widespread implementation of ACL repair [77]. Primary ACL repair has a future for some indications and will be established next to the gold standard of ACL reconstruction and nonsurgical therapy [84].

ACL revision surgery is associated with inferior outcomes compared to primary reconstruction, and numerous open questions remain regarding diagnosis, surgical strategy, and patient selection that require further consensus and evidence [83]. Long-term human studies suggest collectively unacceptable outcomes for open primary repair of the ACL, although a subset of patients achieved acceptable long-term results [5]. ACLD should be considered a contraindication for unicompartmental knee arthroplasty until long-term data is available [6].

Anatomy & Pathophysiology

Ligamentous

The anterior cruciate ligament (ACL) provides resistance to externally applied anterior tibial force but does not resist internal rotational torque during simulated weight-bearing flexion [56]. The anterolateral structures of the knee, including the anterolateral ligament (ALL), contribute to minimizing anterolateral rotational instability [24].

Kinematics and Biomechanics

Graft and Surgical Technique: Single-bundle small grafts tend to produce knee biomechanics significantly different from those of the intact knee [33]. Anatomic single- and double-bundle reconstructions are similarly effective for restoring near-normal dynamic knee function, though neither fully restores normal knee kinematics [29]. There are no differences in knee kinematics between double-bundle and single-bundle via the medial portal technique with a central femoral tunnel [36]. The effective role of the anatomical double-bundle procedure in better restoring knee kinematics should be questioned in an in vivo model [66]. Fixation protocols in double-bundle ACL reconstruction restore knee kinematics without predisposing either graft to failure [65]. Graft-specific differences in knee biomechanics after ACL reconstruction appear to relate to the donor site [69].

Meniscal and Morphological Factors: Lateral meniscal allograft transplantation improves knee kinematic parameters at time zero after surgery, with the biomechanical effect particularly evident during the pivot-shift maneuver [62]. The morphology of the medial tibial insert produces a small but noticeable effect on knee kinematics [39]. The contralateral knee can be used as a reliable normal kinematic control in cruciate ligament deficiency [67].

Post-Reconstruction Biomechanical Alterations: Knee biomechanics in the leg with ACL reconstruction are altered mainly in the sagittal plane during side-cutting compared with the contralateral leg [44]. After ACL reconstruction, surgical limb knee running biomechanics were not restored to the preinjury state by 12 months [72]. Nonsurgical limb mechanics remained unchanged compared with preinjury status one year after ACL reconstruction [72]. Landing biomechanics are altered after ACL reconstruction but tend to recover at 3 years after the procedure [68]. Abnormal biomechanics at 6 months are associated with cartilage degeneration at 3 years after ACL reconstruction [68].

Functional Correlates: Poor knee function after ACL reconstruction is associated with attenuated landing force and knee flexion moment during running [23]. Greater knee flexion excursion and moment in hopping are associated with better knee function following ACL reconstruction [55]. Patients with lower levels of knee function following ACL reconstruction demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis [55].

Neuromuscular and Injury Mechanisms: Neuromuscular electrical stimulation appeared to be safe for the biomechanics of the knee joint with no pathological changes in knee function observed [64]. Jump direction significantly influences knee biomechanics, with lateral jumps identified as the most dangerous of the stop-jumps [26]. Boys demonstrate greater knee frontal moments than girls during the impact phase of cutting maneuvers [57].

Classification

Outcome Definition: Successful anterior cruciate ligament reconstruction must be defined across four equally important categories: early adverse events, patient-reported outcomes, ACL graft failure/recurrent ligament disruption, and clinical measures of knee function and structure [1].

Kaplan Fiber Injury: The classification system used to report Kaplan fiber injury is associated with low inter-rater reliability [41]. The presence of Kaplan fiber injury is not associated with other injuries commonly observed in conjunction with ACL tear [41]. The classification algorithm is an effective tool for prospectively identifying individuals early after anterior cruciate ligament injury who want to pursue nonoperative care or must delay surgical intervention and have good potential to do so [45].

SANTI Classification: The Clinical SANTI classification of arthrogenic muscle inhibition has excellent inter-rater and intra-rater reliability in preoperative and post-operative anterior cruciate ligament rupture [90].

MRI and Anatomical Classification: The plane in which an MRI scan is performed affects the classification of ACL tears [80]. There was poor to slight agreement between MRI classification and arthroscopic findings of specific ACL rupture characteristics [115]. The CLASS MRI sequence is a reliable and reproducible method for identifying ACL footprints [114]. Authors managed to clearly define the concepts of different types of ACL remnants and compared clinical outcomes according to different ACL injury patterns [75]. Medial meniscus tears are most prevalent in type I ACL tears [80]. Type I ACL tears only account for 8% of all ACL tears [80]. Classification of the location of ACL femoral tunnels utilizing 3-D reconstructions of CT data yields moderate to substantial inter- and intra-observer reliability [103].

Other Considerations: The types and extent of tissue injuries are a function of the mechanism of ACL rupture [102]. The concept of an 'anatomic' anterior cruciate ligament reconstruction remains a major focus of active research in the literature, but the true definition remains elusive [106]. Distinct geographic regions within the posterior cruciate ligament have different functional roles depending on the joint angle and the type of load to which the knee is subjected [95]. More than one measurement system is required to accurately describe the femoral origin of the posterior cruciate ligament [97].

Clinical Presentation

Successful anterior cruciate ligament (ACL) reconstruction requires defining success through Patient-reported outcome, Functional outcome, Structural outcome, Avoidance of early adverse events, and Avoidance of graft failure [1]. While timing of reconstruction shows few or no differences in subjective and objective outcomes [2], clinical and functional outcomes for complete tears are generally better with early surgical treatment than with delayed or nonsurgical care [3]. Despite typical mechanisms of injury, initial diagnosis rates in the UK remain poor, often causing unnecessary delay and increased risk of secondary injury [43].

Plain radiographs help establish the diagnosis of an ACL tear in more than one-quarter of patients [8]. MR diagnosis of partial ACL tears is difficult because various tear patterns may be seen, with many partial tears demonstrating MR features indistinguishable from complete ACL tear, mucoid ACL degeneration, or normal ACL [10]. Anterior cruciate ligament mucoid degeneration needs to be more broadly known and properly diagnosed so that progress can be made in its management [25]. Early recognition via MRI is critical for bipolar anterior cruciate ligament injury (simultaneous femoral-sided tear and tibial avulsion fracture), and primary ACL reconstruction is a reliable treatment when anatomical repair is not feasible [12]. An ACL tear suspected on the basis of clinical findings or MRI should have the diagnosis confirmed arthroscopically, especially when ligament reconstruction is envisaged [9]. A modified anterior drawer test could improve the diagnosis of ACL ruptures combined with other clinical information including injury history, clinical examination, and radiological findings [28].

Each ACL-deficient patient should be assessed by a clinician for torsional abnormality using physical examination, as increased femoral anteversion related to infratrochanteric femoral torsion is associated with ACL rupture [46]. Anterolateral complex injuries occur in the majority of ‘isolated’ anterior cruciate ligament ruptures, reinforcing the importance of considering the presence of, and if necessary, treating injuries to structures other than the ACL, as a truly isolated ACL injury is rare [52]. Diagnosing and adequately treating the ligamentous, meniscal and bony lesions associated to ACL rupture is mandatory to address residual rotatory instability after ACL reconstruction surgery [53].

At 10 to 20 years after diagnosis, on average, 50% of those with a diagnosed anterior cruciate ligament or meniscus tear have osteoarthritis with associated pain and functional impairment [30]. Symptomatic individuals with anterior cruciate ligament reconstruction demonstrated weaker knee muscles compared to their asymptomatic counterparts [50]. Closed follow-up, early detection with immediate intervention should be warranted after ACL-R surgeries to manage immediate donor site complications after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft [49].

Consensus statements aim to assist clinicians in managing the ACL-injured patient through anatomic, individualized, and value-based approaches, though larger randomized trials and refined patient-reported outcome measures are needed for future investigation [34]. The 2018 International Olympic Committee consensus statement provides a comprehensive, evidence-informed summary to support clinicians and help children with ACL injury and their parents/guardians make the best possible decisions regarding prevention, diagnosis, and management [31]. The 2022 AAOS clinical practice guidelines for managing anterior cruciate ligament injuries can be demonstrated through case presentations [35]. The aim of the review was to highlight predictors and reasons of failures of ACL-R as well as describe diagnostic procedures to individualize treatment strategies for improved outcome after revision ACL-R [47].

Investigations

Plain radiography

Plain radiographs may help establish the diagnosis of an ACL tear in more than one-quarter of patients [8]. Specific radiographic findings associated with ACL injury include the lateral femoral notch sign [8] and the Tuberculum Intercondylare Tibiae Tertium, which ought to be included in the group of radiologic signs relevant for the diagnosis of ACL lesion [122]. Radiographic assessment of femoral tunnel placement expressed as intercondylar clock time is reproducible and reliable for clinical use, and useful for the evaluation of ACL reconstructive procedures [113].

MRI

MRI with assessment of both ACL morphology and underlying tibial wear pattern provides additional clinical benefit in cases where the extent of posterior bony erosion on the lateral radiograph cannot be assessed with confidence [104]. 1.5-Tesla MRI accurately diagnoses ACL and medial meniscal tears and can reliably complete the diagnostic workup following physical examination, particularly in young adults [111]. However, MR diagnosis of a partial ACL tear is difficult because various tear patterns may be seen, with many partial tears demonstrating MR features indistinguishable from complete ACL tear, mucoid ACL degeneration, or normal ACL [10]. Diagnostic pitfalls may be encountered at the MR interpretation of acute ACL injuries, and these must be taken into account when selecting patients for surgery [110].

MRI is critical for the early recognition of simultaneous femoral-sided tear and tibial avulsion fracture (Bipolar Anterior Cruciate Ligament Injury) [12]. MRI evaluation showed ALL injuries are present in 60.2% of acute ACL injuries in adolescent patients [119]. On the basis of MRI analysis, ALL injuries were found with varying degrees of severity and intensity with noted injuries to associated surrounding fibers in patients with acute ACL rupture [117]. However, ALL injuries were not reliably diagnosed on MRI in the setting of an ACL tear, and physicians should not rely on MRI to diagnose an ALL injury in the presence of an ACL injury [105].

The measurement of the posterior cruciate ligament inclination angle using MRI images may allow for detection of ACL insufficiency and thus assist in an individualized and precise approach to the treatment of injuries to the ACL [118]. Improvement of ACL features on MRI correlates moderately with improved laxity in nonoperative treatment [19]. Plain MRI may be useful to assess graft healing after ACL reconstruction [108]. Simpler methods using MRIs downgraded to a clinical-grade resolution can identify the same knee anatomic factors previously found to significantly contribute to ACL injury risk using sophisticated methods and research-grade resolution MRIs [109].

Other Considerations

An ACL tear suspected on the basis of clinical findings or MRI should have the diagnosis confirmed arthroscopically, especially when ligament reconstruction is envisaged [9]. Even with MRI evidence of disruption in the posterior cruciate ligament (grade II and grade III injuries), posterior cruciate ligament reconstruction may not be clinically indicated at the time of reconstruction and/or repair of other associated injuries [116]. The clinical utility of imaging-based measurement methods for the determination of ACL injury risk requires more reliable techniques that demonstrate consistency between studies [121].

Treatment

Timing and Indications for Surgery

Clinical and functional outcomes for patients with complete anterior cruciate ligament tears are generally better with early surgical treatment than with delayed or nonsurgical care [3]. However, there were few or no differences in subjective and objective outcomes related to timing of anterior cruciate ligament reconstruction [2]. Anterior cruciate ligament reconstruction is justified even in over-40-year-old patients with persisting subjective symptomatic anterior knee instability, with indications based on individual factors rather than age [11]. All patients had a satisfactory outcome after reconstruction of the anterior cruciate ligament in patients at least 40 years old, with no evidence of arthrofibrosis and a lower risk of reinjury compared to non-operative management [99].

Delayed reconstruction and high BMI z score increase the risk of meniscal tear in paediatric and adolescent anterior cruciate ligament injury [76]. Patients with ACL tears treated non-operatively developed secondary meniscal lesions requiring delayed surgical management [76]. Nonoperative management of anterior cruciate ligament tears in children results in less than optimal outcomes, including recurrent instability and secondary meniscal tears [93]. In non-elite patients, persistent grade 2 or 3 laxity beyond 12 weeks should prompt combined anterior cruciate ligament reconstruction with MCL repair and reconstruction [79]. The indications for staged ACL reconstruction and the rehabilitation protocol between stages need to be clearly established [48].

Operative Techniques: Reconstruction vs. Repair

Anterior cruciate ligament primary repair shows preclinical promise, but favorable clinical outcomes have yet to be reported over the long term [4]. Compared with ACL reconstruction, ACL repair shows similar results in clinical outcomes, and it is promising to be an effective alternative treatment for acute ACL rupture [54]. This randomized controlled trial is designed to compare the effectiveness of ACL suture repair with dynamic augmentation against ACL reconstruction, with the primary objective being to investigate if suture repair results in at least equal effectiveness in terms of patient self-reported outcomes 1 year postoperatively [58]. In terms of clinical outcomes, ACL repair appears to provide more superior outcomes compared to ACL reconstruction [60]. Primary ACL repair combined with biologic healing augmentation demonstrated good to excellent long-term outcomes for patients who did not experience secondary ACL insufficiency, with high rates of restoration of knee stability and return to preinjury athletic activities [61].

The study effectively evaluates the differences in clinical outcomes and knee stability in remnant-preserving anterior cruciate ligament reconstruction versus standard ACL reconstruction [27]. Apart from a few exceptional preferential indications, either hamstring tendons or bone-patellar tendon-bone graft may be used for ACL reconstruction [32]. The best evidence supports traditional ACL reconstruction for the surgical management of patients with documented nonfunctional partial tears of the ACL [101].

Operative Techniques: Combined Procedures and Graft Considerations

Satisfactory clinical outcomes after ACL reconstruction at long-term follow-up could be achieved with different modern surgical techniques [14]. The general indication for combined ACL and ALL reconstruction in patients with ligamentous hyperlaxity remains debatable, and further randomized studies with longer follow-up are needed [37]. The combined ACL and ALL reconstruction in patients with chronic ACL injury is an effective and safety solution and leads to good functional outcomes with no increase in complication rate [40]. Combined ACL and ALL reconstruction was found to be effective in improving subjective and objective outcomes [42]. Therefore, a smaller ACL graft should be added to the list of indications for extraarticular procedures [51].

Non-Operative Management

Of patients treated nonoperatively for 1 year after ACL tears, 32% underwent delayed ACL reconstruction [18]. Improvement of ACL features on MRI correlates moderately with improved laxity [19]. Nonoperative treatment of traumatic partial ACL graft rupture can produce satisfactory outcomes in selected patients [86]. Non-operative treatment of partial ACL rupture is justified as it yields good results in the majority of patients, though a substantial number will aggravate their injury over time [89]. Anterior cruciate ligament-injured patients following a nonoperative treatment course and operatively treated patients did not have significantly different rates of returning to pivoting sports after 1 year [96]. On the other hand, non-operative treatment with optional delayed ACLR may be the more cost-effective strategy in the middle age population with moderate activity levels [100].

Outcomes and Rehabilitation

Success of ACL reconstruction is a complex issue requiring comprehensive subjective and objective evaluation beyond simply returning to activity [71]. This review summarizes current topics and research in clinical management of ACL injury, covering evaluation, operative versus nonoperative management, graft selection, rehabilitation, and prevention, while highlighting areas of uncertainty and the current state of ACL research [87].

Complications

Successful anterior cruciate ligament reconstruction requires the avoidance of early adverse events [1]. A history of anterior cruciate ligament reconstruction is a risk factor for further injury, with the highest risk occurring in the first year after reconstruction [13]. At least 1 in 9 patients undergoing ACL reconstruction will experience rerupture or clinical failure at long-term follow-up [16].

Infection (PJI): Patients who develop septic arthritis as a complication of ACL reconstruction surgery have diminished long-term subjective, functional, and radiographic outcomes compared with historical reports of uncomplicated cases [91].

Instability: Revision anterior cruciate ligament reconstruction outcomes are historically inferior to primary ACL reconstruction [107]. The incidence of second anterior cruciate ligament tears in the studied population-based cohort was 6.0%, with 66.7% of these tears occurring on the contralateral side from the original injury [120].

Other Considerations: Bone bruise associated with anterior cruciate ligament rupture entails more severe joint damage that affects joint degenerative progression [20]. Patients with a history of prior cruciate ligament surgery have a substantially higher risk of total knee arthroplasty (TKA) and undergo arthroplasty at a relatively younger age than individuals without such a history [94].

Recovery

Successful anterior cruciate ligament reconstruction requires definition across four equally important categories: early adverse events, patient-reported outcomes, ACL graft failure/recurrent ligament disruption, and clinical measures of knee function and structure [1]. Accelerated rehabilitation programs and large observational cohorts have fundamentally shaped contemporary clinical practice and outcome assessment [22].

Light activity (weeks): Clinical and functional outcomes for patients with complete anterior cruciate ligament tears are generally better with early surgical treatment than with delayed or nonsurgical care [3]. There were few or no differences in subjective and objective outcomes related to timing of anterior cruciate ligament reconstruction [2]. There were few differences between the clinical courses following nonsurgical and surgical treatment of ACL injury in this prospective cohort study [124].

Full activity (months): Satisfactory clinical outcomes after ACL reconstruction at long-term follow-up could be achieved with different modern surgical techniques [14]. Combined ACL reconstruction and medial meniscal transplantation can significantly improve patients' clinical outcomes in the mid to long term [15]. More extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction [17].

Complete recovery / outcome plateau (months): The long-term subjective and objective results of a successful anterior cruciate ligament reconstruction are affected by the status of the menisci and articular surface [70]. At least 1 in 9 patients undergoing ACL reconstruction will have rerupture or clinical failure at long-term follow-up [16]. Patients showed high survivorship (90% of cases) from ACL revision at long-term follow-up [85].

Rehabilitation protocol: A history of anterior cruciate ligament reconstruction is a risk factor for further injury, with the highest risk in the first year after reconstruction [13]. The rate of a subsequent ACL injury was low among the authors' cohort at short-term follow-up [125]. As the length of time from the initial double-bundle ACL reconstruction to revision surgery increased, the pattern of injury more closely resembled that of the native ACL [126].

Functional milestones: Prospective long-term studies are needed to better understand the natural history of bone bruise, identifying prognostic factors and targets of specific treatments that should be developed in light of the overall joint derangements accompanying ACL lesions [20].

Other Considerations: Anterior cruciate ligament primary repair shows preclinical promise, but favorable clinical outcomes have yet to be reported over the long term [4]. Although long-term human studies suggest collectively unacceptable outcomes for open primary repair of the ACL, a subset of patients achieved acceptable long-term results [5]. Two-year follow-up is too short to determine the effectiveness of anterior cruciate ligament primary repair, as historical data suggests failure rates increase with longer-term follow-up [7]. Of patients treated nonoperatively for 1 year after ACL tears, 32% underwent delayed ACL reconstruction [18]. When faced with ACL deficiency, physiological age, condition of the knee at the time of examination, life expectancy and activity level are probably more important than chronologic age [123]. In a 5- to 8-year follow-up, one out of every ten patients had a contralateral ACL rupture, and two out of every ten patients had siblings with a history of ACL rupture [127].

Key Evidence

  • [L5] Successful anterior cruciate ligament reconstruction requires definition across four equally important categories: early adverse events, patient-reported outcomes, ACL graft failure/recurrent ligament disruption, and clinical measures of knee function and structure. (10.1016/j.arthro.2021.11.013)
  • [L2] There were few or no differences in subjective and objective outcomes related to timing of anterior cruciate ligament reconstruction. (10.1016/j.arthro.2013.07.270)
  • [L5] Anterior cruciate ligament primary repair shows preclinical promise, but favorable clinical outcomes have yet to be reported over the long term. (10.1016/j.arthro.2015.08.015)
  • [L4] Although long-term human studies suggest collectively unacceptable outcomes for open primary repair of the ACL, a subset of patients achieved acceptable long-term results. (10.1016/j.arthro.2015.05.007)
  • [L3] Until long-term data is available, however, the authors maintain their recommendation that ACLD be considered a contraindication. (10.1007/s00167-012-2101-8)
  • [L5] Two-year follow-up is too short to determine the effectiveness of anterior cruciate ligament primary repair, as historical data suggests failure rates increase with longer-term follow-up. (10.1016/j.arthro.2023.10.045)
  • [L4] In more than one-quarter of patients, plain radiographs may help to establish the diagnosis of an ACL tear. (10.1007/s00167-014-3022-5)
  • [L2] An ACL tear suspected on the basis of clinical findings or MRI should have the diagnosis confirmed arthroscopically, especially when ligament reconstruction is envisaged. (10.1186/1471-2474-5-21)
  • [L3] MR diagnosis of a partial ACL tear is difficult because various tear patterns may be seen, with many partial tears demonstrating MR features indistinguishable from complete ACL tear, mucoid ACL degeneration, or normal ACL. (10.1007/s00167-011-1617-7)
  • [Paper] Anterior cruciate ligament reconstruction is justified even in over-40-year-old patients with persisting subjective symptomatic anterior knee instability, with indications based on individual factors rather than age. (10.1007/s00402-007-0317-8)
  • [Case_report] Early recognition via MRI is critical, and primary ACL reconstruction is a reliable treatment when anatomical repair is not feasible. (10.1016/j.jisako.2026.101072)
  • [L2] A history of anterior cruciate ligament reconstruction is a risk factor for further injury, with the highest risk in the first year after reconstruction. (10.1177/03635465010290021301)
  • [L1] Satisfactory clinical outcomes after ACL reconstruction at long-term follow-up could be achieved with different modern surgical techniques. (10.1177/2325967124s00279)
  • [L5] Combined ACL reconstruction and MAT can significantly improve patients' clinical outcomes in the mid to long term. (10.1016/j.arthro.2023.01.023)
  • [L4] At least 1 in 9 patients undergoing ACL reconstruction will have rerupture or clinical failure at long-term follow-up. (10.1016/j.arthro.2013.04.014)
  • [L5] More extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction. (10.1177/0363546511402659)
  • [L3] Of patients treated nonoperatively for 1 year after ACL tears, 32% underwent delayed ACL reconstruction. (10.1177/0363546516630751)
  • [L2] Improvement of ACL features on MRI correlates moderately with improved laxity. (10.1016/j.arthro.2014.04.098)
  • [L4] However, prospective long-term studies are needed to better understand the natural history of bone bruise, identifying prognostic factors and targets of specific treatments that should be developed in light of the overall joint derangements accompanying ACL lesions. (10.1007/s00167-018-4993-4)
  • [L5] This editorial highlights landmark studies and the evolution of ACL research, noting that accelerated rehabilitation programs and large observational cohorts have fundamentally shaped contemporary clinical practice and outcome assessment. (10.1177/03635465221124138)
  • [L3] These findings provide greater understanding of the relationship between knee biomechanics during running and clinical assessments of knee function. (10.1007/s00167-017-4810-5)
  • [L4] Biomechanical evidence suggests that the anterolateral structures of the knee, including the ALL, contribute to minimizing anterolateral rotational instability. (10.1177/0363546517751140)
  • [L4] Anterior cruciate ligament mucoid degeneration needs to be more broadly known and properly diagnosed so that progress can be made in its management. (10.1007/s00167-011-1433-0)
  • [L3] Jump direction significantly influenced knee biomechanics, suggesting that lateral jumps are the most dangerous of the stop-jumps. (10.1177/0363546505278696)
  • [L1] The study effectively evaluates the differences in clinical outcomes and knee stability in remnant-preserving anterior cruciate ligament reconstruction versus standard ACL reconstruction. (10.1177/03635465231225984)
  • [L2] It could improve the diagnosis of ACL ruptures combined with other clinical information including injury history, clinical examination, and radiological findings. (10.1186/s13018-021-02381-x)
  • [L1] While neither procedure fully restored normal knee kinematics, both anatomic reconstructions were similarly effective for restoring near-normal dynamic knee function. (10.1007/s00167-021-06479-x)
  • [L4] At 10 to 20 years after diagnosis, on average, 50% of those with a diagnosed anterior cruciate ligament or meniscus tear have osteoarthritis with associated pain and functional impairment. (10.1177/0363546507307396)
  • [L5] This consensus statement provides a comprehensive, evidence-informed summary to support clinicians and help children with ACL injury and their parents/guardians make the best possible decisions regarding prevention, diagnosis, and management. (10.1007/s00167-018-4865-y)
  • [Paper] Apart from a few exceptional preferential indications, either graft may be used for ACL reconstruction. (10.1016/j.otsr.2018.05.014)
  • [L5] Knee biomechanics with a single-bundle small graft tended to be significantly different from those of the intact knee. (10.1177/0363546521995199)
  • [L5] The consensus statements aim to assist clinicians in managing the ACL-injured patient through anatomic, individualized, and value-based approaches, though larger randomized trials and refined patient-reported outcome measures are needed for future investigation. (10.1007/s00167-020-06088-0)
  • [L5] This article demonstrates the clinical application of the 2022 AAOS clinical practice guidelines for managing anterior cruciate ligament injuries through case presentations. (10.5435/jaaos-d-23-00088)
  • [L5] There were no differences in knee kinematics between the DB and SB-central techniques. (10.1177/0363546515611646)
  • [L5] The general indication for combined ACL and ALL reconstruction in patients with ligamentous hyperlaxity remains debatable, and further randomized studies with longer follow-up are needed. (10.1016/j.arthro.2019.04.027)
  • [L5] The morphology of medial tibial insert was also shown to produce a small but noticeable effect on knee kinematics. (10.1007/s00167-014-3249-1)
  • [L3] The combined ACL and ALL reconstruction in patients with chronic ACL injury is an effective and safety solution and leads to good functional outcomes with no increase in complication rate. (10.1007/s00167-018-4934-2)
  • [L4] The classification system used to report Kaplan fiber injury was associated with low inter-rater reliability, and the presence of Kaplan fiber injury was not associated with other injuries commonly observed in conjunction with ACL tear. (10.1007/s00167-021-06730-5)
  • [L2] Combined ACL and ALL reconstruction was found to be effective in improving subjective and objective outcomes. (10.1177/0363546517691517)
  • [L4] Despite a 'typical' mechanism of injury leading to ACL rupture, the rate of initial diagnosis in the UK still remains poor, often leading to unnecessary delay and increased risk of secondary injury. (10.1007/s00167-014-2947-z)
  • [L3] Knee biomechanics in the leg with ACLR were altered mainly in the sagittal plane during side-cutting compared with the contralateral leg. (10.1177/03635465221112940)
  • [L3] The classification algorithm is an effective tool for prospectively identifying individuals early after anterior cruciate ligament injury who want to pursue nonoperative care or must delay surgical intervention and have good potential to do so. (10.1177/0363546507308190)
  • [L3] Each ACL-deficient patient should be assessed by a clinician for torsional abnormality using physical examination. (10.1007/s00167-020-05874-0)
  • [L2] The aim of this review was to highlight predictors and reasons of failures of ACL-R as well as describe diagnostic procedures to individualize treatment strategies for improved outcome after revision ACL-R. (10.1530/eor-23-0085)
  • [L4] The indications for staged ACL reconstruction and the rehabilitation protocol between stages need to be clearly established. (10.1177/0363546519841583)
  • [L5] Closed follow-up, early detection with immediate intervention should be warranted after ACL-R surgeries. (10.1177/2325967120s00037)
  • [L3] Symptomatic individuals with anterior cruciate ligament reconstruction demonstrated weaker knee muscles compared to their asymptomatic counterparts. (10.1002/ksa.12630)
  • [L5] Therefore, a smaller ACL graft should be added to the list of indications for extraarticular procedures. (10.1016/j.arthro.2023.02.004)
  • [L3] These findings reinforce the importance of considering the presence of, and if necessary, treating injuries to structures other than the ACL, as a truly isolated ACL injury is rare. (10.1007/s00167-021-06543-6)
  • [L5] Diagnosing and adequately treating the ligamentous, meniscal and bony lesions associated to ACL rupture is mandatory. (10.1177/2325967124s00370)
  • [L1] Compared with ACL reconstruction, ACL repair shows similar results in clinical outcomes, and it is promising to be an effective alternative treatment for acute ACL rupture. (10.1186/s13018-024-04812-x)
  • [L3] Patients with lower levels of knee function following ACLR demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis. (10.1007/s00167-018-5197-7)
  • [L5] The study established an experimental protocol to measure knee kinematics during weight-bearing flexion. (10.1016/j.arthro.2010.04.069)
  • [L2] The role of kinematics in mediating the KFM0-70 provides means for modification of this risk factor, but as boys had higher joint moments, continued investigation into sex-dependent biomechanical risk factors is warranted. (10.1007/s00167-023-07340-z)
  • [L1] This randomized controlled trial is designed to compare the effectiveness of ACL suture repair with dynamic augmentation against ACL reconstruction, with the primary objective being to investigate if suture repair results in at least equal effectiveness in terms of patient self-reported outcomes 1 year postoperatively. (10.1186/s12891-018-2028-4)
  • [L1] In terms of clinical outcomes, ACL repair appears to provide more superior outcomes compared to ACL reconstruction. (10.1177/2325967125s00048)
  • [L4] Primary ACL repair combined with biologic healing augmentation demonstrated good to excellent long-term outcomes for patients who did not experience secondary ACL insufficiency, with high rates of restoration of knee stability and return to preinjury athletic activities. (10.1177/0363546518805740)
  • [L4] Lateral MAT improved knee kinematic parameters at time zero after surgery; the biomechanical effect of MAT was particularly evident during the pivot-shift maneuver. (10.1177/23259671211000459)
  • [L2] The neuromuscular electrical stimulation appeared to be safe for biomechanics of knee joint with no pathological changes in knee function observed. (10.1155/2013/802534)
  • [L5] Both fixation protocols restored knee kinematics without predisposing either graft to failure. (10.1177/0363546507300822)
  • [L4] The effective role of the anatomical double-bundle procedure in better restoring knee kinematics should be questioned in an in vivo model. (10.1177/0363546507305677)
  • [L3] These findings suggest that the contralateral knee can be used as a reliable normal kinematic control. (10.1177/0363546508319051)
  • [L2] Landing biomechanics are altered after ACLR but biomechanical abnormalities tend to recover at 3 years after ACLR. (10.1016/j.arthro.2018.07.033)
  • [L3] There are graft-specific differences in knee biomechanics after anterior cruciate ligament reconstruction that appear to relate to the donor site. (10.1177/0363546504266483)
  • [L3] The long-term subjective and objective results of a successful anterior cruciate ligament reconstruction are affected by the status of the menisci and articular surface. (10.1177/03635465000280040201)
  • [L5] Success of ACL reconstruction is a complex issue requiring comprehensive subjective and objective evaluation beyond simply returning to activity. (10.1007/s00167-017-4559-x)
  • [L2] After ACLR, surgical limb knee running biomechanics were not restored to the preinjury state by 12 months, while nonsurgical limb mechanics remained unchanged as compared with preinjury. (10.1177/03635465211026665)
  • [L2] They state that they managed to clearly define the concepts of different types of ACL remnants and compared clinical outcomes according to different ACL injury patterns. (10.1016/j.arthro.2013.08.018)
  • [L3] Patients with ACL tears treated non-operatively developed secondary meniscal lesions requiring delayed surgical management. (10.1007/s00167-018-5201-2)
  • [L5] Prospective studies with sufficient follow-up comparing the outcomes and failure rates of ACL repair versus reconstruction are needed prior to widespread implementation of ACL repair. (10.1016/j.jisako.2023.09.001)
  • [L5] An evidence-based approach to anterior cruciate ligament reconstruction integrates best available research with clinical expertise and patient values, emphasizing appropriately powered expertise-based trials and best-practice rehabilitation protocols to optimize outcomes. (10.1016/j.csm.2012.08.008)
  • [L5] In non-elite patients, persistent grade 2 or 3 laxity beyond 12 weeks should prompt combined anterior cruciate ligament reconstruction with MCL repair and reconstruction. (10.1002/arj.70105)
  • [L4] The plane in which an MRI scan is performed affects the classification of ACL tears. (10.1007/s00167-022-07068-2)
  • [L3] When clinical indications exist, simultaneous bilateral anterior cruciate ligament reconstruction is recommended as a safe, effective, and cost-effective option compared to staged procedures. (10.1177/03635465020300062201)
  • [L4] The substantial clinical benefit thresholds for patient-reported outcome measures were determined after primary anterior cruciate ligament reconstruction. (10.1016/j.arthro.2025.05.016)
  • [L5] ACL revision surgery is associated with inferior outcomes compared to primary reconstruction, and numerous open questions remain regarding diagnosis, surgical strategy, and patient selection that require further consensus and evidence. (10.1007/s00167-022-06950-3)
  • [L5] Primary ACL repair has a future for some indications and will be established next to the gold standard of ACL reconstruction and nonsurgical therapy. (10.1016/j.arthro.2019.05.003)
  • [L4] Patients showed high survivorship (90% of cases) from ACL revision at long-term follow-up. (10.1177/23259671251389126)
  • [L3] Nonoperative treatment of traumatic partial ACL graft rupture can produce satisfactory outcomes in selected patients. (10.1177/23259671231182124)
  • [L5] This review summarizes current topics and research in clinical management of ACL injury, covering evaluation, operative versus nonoperative management, graft selection, rehabilitation, and prevention, while highlighting areas of uncertainty and the current state of ACL research. (10.1007/s00167-021-06825-z)
  • [L3] Non-operative treatment of partial ACL rupture is justified as it yields good results in the majority of patients, though a substantial number will aggravate their injury over time. (10.1007/s001670050015)
  • [L2] Excellent intra-rater and inter-rater reliability of the AMI classification system was found in patients with recent ACL rupture and post-operatively. (10.1002/ksa.12586)
  • [L4] Patients who develop septic arthritis as a complication of ACL reconstruction surgery have diminished long-term subjective, functional, and radiographic outcomes compared with historical reports of uncomplicated cases, likely related to pain from advanced arthritis. (10.1177/0363546512461903)
  • [L5] Nonoperative management of anterior cruciate ligament tears in children results in less than optimal outcomes, including recurrent instability and secondary meniscal tears. (10.1177/0363546504271209)
  • [L3] Patients with a history of prior cruciate ligament surgery have substantially higher risk of TKA and undergo arthroplasty at a relatively younger age than individuals without a history of prior cruciate ligament surgery. (10.1302/0301-620x.106b3.bjj-2023-0425.r2)
  • [L5] Distinct geographic regions within the posterior cruciate ligament have different functional roles depending on the joint angle and the type of load to which the knee is subjected. (10.1177/0363546504267152)
  • [L3] Anterior cruciate ligament-injured patients following a nonoperative treatment course and operatively treated patients did not have significantly different rates of returning to pivoting sports after 1 year. (10.1177/0363546512458424)
  • [L5] More than one measurement system is required to accurately describe the femoral origin of the posterior cruciate ligament. (10.1177/03635465020300050301)
  • [L4] All patients had a satisfactory outcome after reconstruction of the anterior cruciate ligament, with no evidence of arthrofibrosis and a lower risk of reinjury compared to non-operative management. (10.2106/00004623-199802000-00005)
  • [L1] On the other hand, non-operative treatment with optional delayed ACLR may be the more cost-effective strategy in the middle age population with moderate activity levels. (10.1007/s00167-022-07087-z)
  • [L5] The best evidence supports traditional ACL reconstruction for the surgical management of patients with documented nonfunctional partial tears of the ACL. (10.5435/jaaos-d-20-00242)
  • [L5] The types and extent of these tissue injuries are a function of the mechanism of ACL rupture. (10.1177/0363546508318046)
  • [L3] Classification of the location of ACL femoral tunnels utilizing 3-D reconstructions of CT data yields moderate to substantial inter- and intra-observer reliability. (10.1007/s00167-011-1814-4)
  • [L2] MRI with assessment of both the ACL morphology and the underlying tibial wear pattern appears to provide additional clinical benefit in cases in which the extent of posterior bony erosion on the lateral radiograph cannot be assessed with confidence. (10.1007/s00167-014-2994-5)
  • [L3] However, ALL injuries were not reliably diagnosed on MRI in the setting of an ACL tear, and physicians should not rely on MRI to diagnose an ALL injury in the presence of an ACL injury. (10.1016/j.arthro.2019.09.039)
  • [L5] The concept of an 'anatomic' anterior cruciate ligament reconstruction remains a major focus of active research in the literature, but the true definition remains elusive. (10.1016/j.arthro.2019.03.017)
  • [L5] Revision anterior cruciate ligament reconstruction (ACLR) outcomes are historically inferior to primary ACLR, and the procedure should be approached as a different entity requiring detailed assessment of failure causes. (10.1136/jisakos-2020-000457)
  • [L4] Plain MRI may be useful to assess graft healing after ACL reconstruction. (10.1007/s00167-014-2856-1)
  • [L2] Simpler methods using MRIs downgraded to a clinical-grade resolution can identify the same knee anatomic factors previously found to significantly contribute to ACL injury risk using sophisticated methods and research-grade resolution MRIs. (10.1177/03635465211024249)
  • [L5] MRI has been established as a highly useful method for evaluating the ACL; however, diagnostic pitfalls may be encountered at the MR interpretation of acute injuries, and these must be taken into account when selecting patients for surgery. (10.1007/s00167-017-4701-9)
  • [L3] 1.5-Tesla MRI accurately diagnoses ACL and medial meniscal tears and can reliably complete the diagnostic workup following physical examination, particularly in young adults. (10.1186/s12891-021-04011-3)
  • [L4] This simple radiographic assessment is reproducible and reliable for clinical use, and useful for the evaluation of ACL reconstructive procedures. (10.1007/s00167-010-1243-9)
  • [L2] The CLASS MRI sequence is a reliable and reproducible method for identifying ACL footprints. (10.1002/ksa.12555)
  • [L2] There was poor to slight agreement between MRI classification and arthroscopic findings of specific ACL rupture characteristics. (10.1177/2325967121992472)
  • [L2] Even with MRI evidence of disruption in the posterior cruciate ligament (grade II and grade III injuries), posterior cruciate ligament reconstruction may not be clinically indicated at the time of reconstruction and/or repair of other associated injuries. (10.1177/0363546510391154)
  • [L4] On the basis of MRI analysis, ALL injuries were found with varying degrees of severity and intensity with noted injuries to associated surrounding fibers in patients with acute ACL rupture. (10.1016/j.arthro.2018.08.032)
  • [L3] The measurement of this angle using MRI images may allow for detection of ACL insufficiency and thus assist in an individualized and precise approach to the treatment of injuries to the ACL. (10.1007/s00167-021-06789-0)
  • [L4] MRI evaluation showed ALL injuries are present in 60.2% of acute ACL injuries in adolescent patients. (10.1016/j.arthro.2019.02.034)
  • [L3] The incidence of second ACL tears in this population-based cohort was 6.0%, with 66.7% of these tears occurring on the contralateral side from the original injury. (10.1177/0363546517694026)
  • [L1] The clinical utility of imaging-based measurement methods for the determination of ACL injury risk requires more reliable techniques that demonstrate consistency between studies. (10.1177/0363546512442307)
  • [L3] A positive finding of this structure ought to be included in the group of radiologic signs relevant for the diagnosis of ACL lesion. (10.1177/03635465010290060601)
  • [L3] When faced with ACL deficiency, physiological age, condition of the knee at the time of examination, life expectancy and activity level are probably more important than chronologic age. (10.1007/s00167-010-1242-x)
  • [L2] There were few differences between the clinical courses following nonsurgical and surgical treatment of ACL injury in this prospective cohort study. (10.2106/jbjs.m.01054)
  • [L4] The rate of a subsequent ACL injury was low among the authors' cohort at short-term follow-up. (10.1177/23259671211000460)
  • [L4] As the length of time from the initial DB-ACL reconstruction to revision surgery increased, the pattern of injury more closely resembled that of the native ACL. (10.1007/s00167-010-1297-8)
  • [L3] In a 5- to 8-year follow-up, one out of every ten patients had a contralateral ACL rupture, and two out of every ten patients had siblings with a history of ACL rupture. (10.1007/s00167-019-05781-z)

See Also

References

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