Navigated knee kinematics after cutting of the ACL and its secondary restraint

Does lateral extra-articular tenodesis affect knee stability in cases with isolated anterior cruciate ligament reconstruction?

Objective

The purpose of this randomised controlled trial was to assess the effect on knee function and stabilising effectiveness of lateral extra-articular tenodesis (LET) in anterior cruciate ligament (ACL) restoration.

Methods

A prospective randomised clinical study that compared the functional outcomes of two groups-one undergoing anatomic single bundle ACL reconstruction (ASB-ACLR) with ilio-tibial band tenodesis (LET) for 20 patients, and the other undergoing ASB-ACLR-was carried out between February 2020 and August 2022.

Results

By combining Lateral Extra-articular Tenodesis (LET) with intra-articular Anterior Cruciate Ligament Reconstruction (ACLR), our study observed a significant reduction in the occurrence of high-grade pivot-shift phenomena. Prior to surgery, both Groups A and B exhibited graded (D) pivot-shift test results. However, post-surgery, the pivot-shift test yielded negative results in 60% of patients in Group A and 90% of patients in Group B. The statistical analysis revealed a notable difference between the two groups, as indicated by a P-value of 0.003. Upon conducting a brief follow-up, we evaluated the Lysholm score, and anterior knee stability of ACLR with LET, finding no statistically significant difference compared to those of single ACLR. The Lachman tests also revealed no significant disparity between the two groups (p = 0.106). Analyzing the Lysholm scores in Group A and Group B, we observed an increase to 90.70% and 91.10%, respectively.

Conclusion

Rotational stability is much improved when lateral extra-articular tenodesis (LET) utilizing the ilio-tibial band as an augmentation is used in ACL restoration. Especially useful for high-grade pivot-shift phenomena is this technique.

Dynamic radiostereometry can objectively quantify the kinematic laxity patterns and rotation instability of the knee during a pivot-shift test

PURPOSE

The pivot-shift test is used to clinically assess knee instability in patients with anterior cruciate ligament (ACL) lesions; however, it has low interobserver reliability. Dynamic radiostereometry (dRSA) is a highly precise and noninvasive method for the objective evaluation of joint kinematics. The purpose of this study was to quantify precise knee kinematics during a pivot-shift test using dRSA imaging.

METHOD

Eight human donor legs, including hemipelvises, were evaluated. Arthroscopic intervention was performed inducing ligament lesions in the ACL, and anterolateral ligament (ALL) section was performed as a capsular incision. The pivot-shift test was recorded with dRSA on knees with intact ligaments, ACL-deficient and ACL + ALL-deficient knees.

RESULTS

A pivot-shift pattern was identifiable after ligament lesion, as a change in tibial posterior drawer velocity from 7.8 mm/s (95% CI: 3.7; 11.9) in ligament intact knees to 30.4 mm/s (95% CI 23.0; 38.8) after ACL lesion to 35.1 mm/s (95% CI 23.4; 46.7) after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm (95% CI 2.1; 3.4) in ligament intact knees to 7.2 mm (95% CI 5.5; 8.9) after ACL lesion to 7.6 mm (95% CI 5.5; 9.8) after combined lesion. A statistically significant increase in tibial external rotation towards the end of the pivot-shift motion was observed when progressing from intact to ACL + ALL-deficient knees (p < 0.023).

CONCLUSION

This experimental study demonstrates the feasibility of dRSA to objectively quantify the kinematic laxity patterns of the knee during the pivot-shift test. The dynamic parameters obtained through dRSA revealed the kinematic changes from ACL to combined ACL-ALL ligament lesion.

LEVEL OF EVIDENCE

Not applicable.

Anterolateral Ligament and Kaplan Fiber Injury Both Occur Frequently in Acute Anterior Cruciate Ligament-Injured Knees

BACKGROUND AND OBJECTIVES

The association of ALL and KF injuries in anterior cruciate ligament (ACL)-deficient knees remain topics of conflicting research despite improved magnetic resonance imaging (MRI). We aimed to evaluate the rate of the anterolateral ligament (ALL) and Kaplan fibers (KF) injuries in adults with acute ACL injuries using MRI.

METHODS

We retrospectively reviewed 64 patients with clinical and MRI diagnoses of acute ACL tears. Two radiologists analyzed and categorized the status of the ALL and KF in all patients as intact, partially injured, or completely injured. Interobserver agreement was assessed. Injuries to the collateral ligaments, ITB and posterior cruciate ligament (PCL) were also evaluated.

RESULTS

The mean age of the patients was 33 years. ALL injuries were observed in 46 (71%) patients, among whom 33 (71%) had partial and 13 (28%) had complete injuries. KF injuries were identified in 32 (50%) patients, with 28 (87.5%) of them having partial and 4 (12.5%) having complete injuries. Combined injuries of both ALL and KF were found in 25 (32.4%) patients (p-value of 0.266). The agreement between the examiners ranged from moderate to substantial (Kappa between 0.55 and 0.75), with the highest agreement observed in cases of KF injuries (Kappa = 0.75).

CONCLUSIONS

ALL and KF injuries were prevalent in acute ACL-injured knees with rates of injury of 71% and 50%, respectively. ALL injuries were more frequent and more frequently severe compared to KF injuries.

Must a Knee with Anterior Cruciate Ligament Deficiency and High-grade Pivot Shift Test Present an Increase in Internal Rotation?

Objective:  Rupture of the anterior cruciate ligament (ACL) is one of the most common injuries in athletes and is often associated with damage to anterolateral structures. This combination of injuries presents itself clinically as a high-grade pivot shift test. The hypothesis of this study is that patients with ACL deficiency and high-grade pivot shift test should have an increased internal knee rotation. Methods:  Twenty-two patients were tested. After effective spinal anesthesia, two tests were performed with the patient in supine position. First, the bilateral pivot shift test was performed manually, and its grade was recorded. Then, with the knee flexed to 90 degrees, the examiner drew the projection of the foot in a neutral position and in maximum internal rotation, and the angle of internal rotation was measured from the axes built between the central point of the heel and the hallux. Results:  In the ACL-deficient knee, it was observed that there is a statistically significant average internal rotation (IR) delta of 10.5 degrees between the groups when not adjusted for age, and 10.6 degrees when adjusted for age. Conclusions:  Knees with ACL deficiency and with pivot shift test grade I do not show increased internal rotation in relation to knees with intact ACL. Knees with ACL deficiency and with pivot shift test grades II and III show increased internal rotation in comparison to healthy knees.

The Iliotibial Band is the Main Secondary Stabilizer for Anterolateral Rotatory Instability and both a Lemaire Tenodesis and Anterolateral Ligament Reconstruction Can Restore Native Knee Kinematics in the Anterior Cruciate Ligament Reconstructed Knee: A Systematic Review of Biomechanical Cadaveric Studies

PURPOSE

To obtain a comprehensive overview of comparative biomechanical cadaveric studies investigating the effect of both the iliotibial band (ITB) and anterolateral ligament (ALL) on anterolateral rotatory instability (ALRI) in anterior cruciate ligament (ACL)-injured knees, and the effect of lateral extra-articular tenodesis (LET) versus ALL reconstruction (ALLR) in ACL-reconstructed knees.

METHODS

An electronic search was performed in the Embase and MEDLINE databases for the period between January 1, 2010, and October 1, 2022. All sectioning studies comparing the role of both the ITB and ALL on ALRI and all studies comparing the effect of both LET and ALLR were included. Articles were assessed for methodological quality according to the Quality Appraisal for Cadaveric Studies scale.

RESULTS

Data of 15 studies were included, representing the mean values of biomechanical data collected from 203 cadaveric specimens, with sample sizes ranging from 10 to 20 specimens. All 6 sectioning studies reported that the ITB acts as a secondary stabilizer to the ACL and helps resist internal knee rotation, whereas in only 2 of 6 sectioning studies the ALL contributed significantly to tibial internal rotation (IR). Most reconstruction studies reported that both a modified Lemaire tenodesis and an ALLR could significantly reduce the residual ALRI in isolated ACL-reconstructed knees and were able to restore IR stability/IR stability during the pivot shift.

CONCLUSIONS

The ITB acts as the main secondary stabilizer to the ACL in resisting IR/IR during pivot shift and an anterolateral corner (ALC) reconstruction with either a modified Lemaire tenodesis and ALLR can improve residual knee rotatory laxity in ACL reconstructed knees.

CLINICAL RELEVANCE

This systematic review provides insight in the biomechanical function of the ITB and ALL and emphasizes the importance of adding an ALC reconstruction to ACL reconstruction.

The Role of Anterolateral Ligament Reconstruction or Lateral Extra-articular Tenodesis for Revision Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Comparative Clinical Studies

BACKGROUND

After its success in restoring rotational stability and reducing failure rates in primary anterior cruciate ligament reconstruction (ACLR), lateral extra-articular tenodesis (LET) or anterolateral ligament reconstruction (ALLR) has been endorsed for use in revision ACLR surgery, where failure rates are historically higher.

PURPOSE

To perform a systematic review and meta-analysis on whether the addition of a LET or ALLR results in superior clinical outcomes and stability compared with isolated revision ACLR (iACLR).

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase were used to perform a systematic review and meta-analysis of comparative studies using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria with the following search terms: ("extra-articular" OR "tenodesis" OR "anterolateral ligament" OR "iliotibial") AND ("anterior cruciate ligament") AND ("revision" OR "re-operation"). Data pertaining to all patient-reported outcome measures (PROMs), rotational stability, and postoperative complications were extracted from each study.

RESULTS

After abstract and full-text screening, 10 clinical comparative studies were included. There were 793 patients, of whom 390 had an iACLR while 403 had an ACLR augmented with a LET or an ALLR (augmented ACLR [aACLR]). The mean time for assessment of PROMs was 35 months. The aACLR group had superior International Knee Documentation Committee (IKDC) scores (standardized mean difference [SMD], 0.27; 95% CI, 0.01 to 0.54; P = .04), rotational stability (odds ratio [OR], 2.77; 95% CI, 1.91 to 4.01; P < .00001), and lower side-to-side difference (OR, -0.53; 95% CI, -0.81 to -0.24; P = .0003) than those without the augmentation. Furthermore, they were less likely to fail (OR, 0.44; 95% CI, 0.24 to 0.80; P = .007). Subgroup analysis in the higher-grade laxity cohort (grade ≥2) revealed an even greater IKDC score (SMD, 0.51; 95% CI, 0.16 to 0.86; P = .005) and an improved Lysholm score (SMD, 0.45; 95% CI, 0.24 to 0.67; P < .0001) in the aACLR group.

CONCLUSION

Revision aACLR with a LET or an ALLR can improve subjective IKDC scores, restore rotational stability, and reduce failure rates compared with iACLR. Although controversy remains on the necessity of augmenting all revision ACLRs, the present meta-analysis advocates adding a lateral procedure, particularly in those with a higher-grade pivot shift.

Progress in research on and classification of surgical methods of arthroscopic reconstruction of the ACL and ALL using a shared tendon graft through the femoral tunnel

Anterior cruciate ligament (ACL) tear is a common clinical injury, and ACL reconstruction has reached a very mature stage. However, with the accumulation of cases, scholars have found that isolated ACL reconstruction may not completely solve the problem of knee rotational stability. With the increase in our understanding of knee joint structure, ACL combined with anterolateral ligament (ALL) reconstruction has become accepted by most scholars, and this operation has also achieved good clinical results. At present, there is no unified surgical method for ACL combined with ALL reconstruction. There are differences in bone tunnel location, reconstruction methods, and graft selection. Compared with the independent reconstruction of the ACL and ALL during the operation, shared tendon graft reconstruction of the ACL and ALL has the advantages of preserving tendon and avoiding tunnel convergence. So far, there is no relevant literature summarizing the reconstruction of the ACL and ALL with a shared tendon graft. This paper reviews the anatomic study of the ALL, the study of isometric points, surgical indications, and surgical methods and their classification for shared tendon graft reconstruction of the ACL and ALL.

Muscle function, Lysholm score and hop performance in individuals with clinical indications for the combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee: A cross-sectional study

OBJECTIVE

To evaluate hip and knee muscular function, knee patient-reported outcome measures and hop performance in patients with a clinical indication for combined ACL+ALL reconstruction surgery compared to patients with an isolated ACL reconstruction surgery indication (preoperative phase) and to a control group.

DESIGN

Cross-sectional study.

METHODS

The sample was composed of male individuals, aged between 18 and 59 years, divided into three groups (ACL, ACL+ALL and Control). Isokinetic dynamometry was performed for the flexor and extensor knee muscles and for the hip abductors and adductors. SLHT, COHT and the Lysholm score were performed. Pain, swelling, and thigh trophism were also measured.

RESULTS

The study participants were 89 male individuals: 63 in the injury group and 26 in the control group. After applying the criteria for an ALL reconstruction indication, 33 patients were assigned to the ACL Group and 30 patients to the ACL+ALL Group. Regarding knee and hip muscle function, both groups presented worse results when compared to the control group, however, did not show significant differences compared to each other. Regarding the functional variables, the ACL+ALL group showed a significantly shorter distance achieved in the Crossover Hop Test than the other groups, as well as more pain during the tests.

CONCLUSION

Knee and hip muscular functions are impaired after an ACL injury and do not seem to be influenced or worsened in individuals with greater rotational instability with clinical indications for combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee.

Frequency of anterolateral ligament tears and ramp lesions in patients with anterior cruciate ligament tears and associated injuries indicative for these lesions-a retrospective MRI analysis

OBJECTIVES

To assess the frequency of anterolateral ligament (ALL) tears and ramp lesions (RL) detected with MRI in patients with anterior cruciate ligament (ACL) tears and to describe associated injuries indicative for these lesions.

METHODS

In this retrospective study, 164 patients with surgically verified ACL tears were included. Preoperative MRI scans were reviewed for ALL tears and different types of RL. All coexisting meniscal tears, tears of the medial (MCL) and lateral collateral band (LCL), and posterior-medial tibial bone marrow edema (BME) were recorded. The frequency of ALL tears and RL was assessed and coexisting injuries were correlated using Pearson's chi-square test. A p < 0.05 was defined as statistically significant. In cases of multiple testing, Bonferroni's correction was applied.

RESULTS

ALL tears and RL combined were detected in 28 patients (17.1%), ALL tears in 48 patients (29.3%), and RL in 54 patients (32.9%) which were significantly associated to each other. ALL tears were significantly associated with tears of the posterior horn of the lateral meniscus (PHLM), BME, and with tears of the LCL and MCL. RL were significantly associated with tears of the posterior horn of the medial (PHMM) and PHLM, with BME, and with tears of the LCL.

CONCLUSIONS

ACL tears are associated with RL or ALL tears in about one-third of cases and with both lesions combined in about one-fifth of cases. ALL tears and RL are significantly associated with additional posttraumatic injuries, which can thus be indicative of these lesions.

KEY POINTS

• ACL tears were associated with ramp lesions or ALL tears in about one-third of the cases. • Ramp lesions and ALL tears were significantly associated with each other, tear in the PHLM, tear in the LCL, and BME. • ALL tears were more frequently associated with instable classified ramp lesion type 4b and type 5.

Untreated Injuries to the Anterolateral Capsular Structures Do Not Affect Outcomes and Kinematics after Anatomic Anterior Cruciate Ligament Reconstruction

BACKGROUND

Injuries to the anterolateral complex (ALC) may contribute to increased rotatory knee laxity. However, it has not been evaluated whether such injuries affect in vivo kinematics when treated in situ. The purpose of this study was to determine the grade of ALC injury and its effect on kinematic and clinical outcomes of ACL-injured patients 24 months after anatomic ACL reconstruction. It was hypothesized that injury to the ALC would be significantly related to patient-reported outcomes (PROs) and in vivo knee kinematics during downhill running.

METHODS

Thirty-five subjects (mean age: 22.8 ± 8.5 years) participating in a randomized clinical trial to compare single- and double-bundle ACL reconstruction were included in the study. Subjects were divided into two groups based on the presence or absence of injury to the ALC, as determined on MRI scans performed within 6 weeks of injury. None of the patients underwent treatment for these ALC injuries. At 24 months, PROs, including the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF), Knee injury and Osteoarthritis Outcome Score (KOOS) and in vivo knee kinematics during downhill running, were obtained. Pivot-shift test results, PROs and in vivo knee kinematics were compared between groups with and without ALC injury using the Pearson's Chi Squared test and Mann-Whitney U test with significance set at p < 0.05.

RESULTS

The average interval between injury and performing the MRI scans was 9.5 ± 10 days. ALC injury was observed in 17 (49%) study participants. No significant differences were detected in PROs and in vivo kinematics between subjects with and without ALC injury (n.s.).

CONCLUSION

The findings of this study demonstrate that MRI evidence of an ALC injury does not significantly affect in vivo knee kinematics and PROs even in individuals with a high-grade ALC injury. Injuries to the ALC as observed on MRI might not be a useful indication for an anterolateral procedure.

Biomechanical Comparison of Anterior Cruciate Ligament Reconstruction Using a Single-Bundle Round or Ribbon-like Hamstring Tendon Graft

BACKGROUND

Persistent instability of the knee is reported in up to 30% of patients after anterior cruciate ligament (ACL) reconstruction. Based on anatomic findings showing that ACL is a flat ribbon-like structure that twists during knee flexion, a new surgical ACL reconstruction technique using a ribbon-like graft has been developed. However the effect of this surgical technique on knee kinematics has not yet been evaluated.

PURPOSE

To compare the anteroposterior and rotational stability of the knee after ACL reconstruction using single-bundle (SB) round and ribbon-like grafts in anterolateral-intact/deficient knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve human fresh-frozen cadaveric knees were tested with a 6 degrees of freedom robotic system. Internal rotation and anterior translation of the knee were recorded from 0° to 90° of flexion. A full kinematic assessment was performed in each of the following conditions: (1) intact knee, (2) after sectioning of the ACL, (3) after ACL reconstruction using a SB hamstring tendon graft in a round configuration and a ribbon-like configuration, and (4) after sectioning of the anterolateral structures. One-way analysis of variance and post hoc Tukey tests were used for statistical analyses.

RESULTS

When compared with the intact knee, the ACL-deficient knee demonstrated a mean ± SD increase in anterior translation and internal rotation of 6.3 ± 2.5 mm (P < .01) and 5.8°± 2.3° (P < .01), respectively. After ACL reconstruction using a SB ribbon-like graft, the mean difference in anterior translation and internal rotation as compared with the intact knee was -0.1 ± 1.5 mm (P = .842) and 0.0°± 1.1° (P = .999). These differences from the intact knee were also not significant after ACL reconstruction using a round graft (-0.1 ± 1.3 mm, P = .999; -0.5°± 1.5°, P = .401). In the ACL-reconstructed knee using either a ribbon-like or round graft, sectioning of the anterolateral structures did not induce a significant increase of anterior translation and internal rotation of the knee.

CONCLUSION

ACL reconstruction using a SB ribbon-like or round graft restored the kinematics of the intact knee at time zero. Secondary sectioning of the anterolateral structures in the ACL-reconstructed knee using both types of graft did not significantly affect the anterior translation and internal rotation of the knee.

CLINICAL RELEVANCE

This is the first biomechanical study on the new ACL reconstruction technique using a ribbon-like graft.

Anatomical and Biomechanical Characteristics of the Anterolateral Ligament: A Descriptive Korean Cadaveric Study Using a Triaxial Accelerometer

Background and Objectives: The anterolateral ligament (ALL) could be the potential anatomical structure responsible for rotational instability after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to investigate the anatomical and biomechanical characteristics of the ALL in Korean cadaveric knee joints. Materials and Methods: Twenty fresh-frozen cadaveric knees were dissected and tested. Femoral and tibial footprints of the ALL were recorded. Pivot shift and Lachman tests were measured with KiRA. Results: The prevalence of ALL was 100%. The average distance of the tibial footprint to the tip of the fibular head was 19.85 ± 3.41 mm; from the tibial footprint to Gerdy's tubercle (GT) was 18.3 ± 4.19 mm; from the femoral footprint to the lateral femoral epicondyle was 10.25 ± 2.97 mm. ALL's footprint distance was the longest at 30° of flexion (47.83 ± 8.05 mm, p < 0.01) in a knee with intact ALL-ACL and neutral rotation. During internal rotation, the footprint distance was the longest at 30° of flexion (50.05 ± 8.88 mm, p < 0.01). Internal rotation produced a significant increase at all three angles after ACL-ALL were transected (p = 0.022), where the footprint distance was the longest at 30° of flexion (52.05 ± 7.60 mm). No significant difference was observed in KiRA measurements between intact ALL-ACL and ALL-transected knees for pivot shift and Lachman tests. However, ACL-ALL-transected knees showed significant differences compared to the intact ALL-ACL and ALL-transected knees (p < 0.01). Conclusions: The ALL was identified as a distinct ligament structure with a 100% prevalence in this cadaveric study. The ALL plays a protective role in internal rotational stability. An isolated ALL transection did not significantly affect the ALL footprint distances or functional stability tests. Therefore, the ALL is thought to act as a secondary supportive stabilizer for rotational stability of the knee joint in conjunction with the ACL.

Anterolateral ligament MRI of the knee in ACL injuries: MRI abnormalities association with instability

OBJECTIVE

To evaluate anterolateral ligament abnormalities (ALL) at MRI scans and correlate with data from clinical instability tests (Lachman and pivot shift) performed under anesthesia in patients with acute anterior cruciate ligament (ACL) tears. Furthermore, perform multivariate analysis with other variables to isolate the ALL contribution to instability from other abnormalities.

METHODS

Retrospective analysis of MRI and instability tests of 95 patients with ACL tears. The ALL was classified as no abnormality, abnormality without discontinuity, and discontinuity. Injuries in other knee ligament structures and menisci were also assessed. Results of instability tests (pivot shift and Lachman) with the patient anesthetized for arthroscopic ACL reconstruction were obtained from the patient database. Statistical analysis was performed using the IBM SPSS 22.

RESULTS

ALL abnormalities and iliotibial band (ITB), lateral (LCL), and medial (MCL) collateral ligament injuries showed a statistically significant correlation with the pivot shift test. The ALL MRI abnormalities were associated with the high-grade pivot shift results (p < 0.0005), with an odds ratio of 55.9 for high degrees of pivot shift in patients with abnormal ALL. The logistic model for all variables analyzed with the results of the pivot shift test demonstrated that the ALL was the only variable with a statistically significant correlation in the model (p < 0.0005).

CONCLUSION

MRI ALL abnormalities in patients with ACL injuries have a significant association with pivot shift test results in patients under anesthesia. The logistic model for high - grade pivot shift test results demonstrated that ALL abnormalities were the only variable with significant correlation.

KEY POINTS

• Evaluating the anterolateral ligament with MRI in acute anterior cruciate ligament injuries is useful to predict higher grades of pivot shift test in the moment of the arthroscopic reconstruction. • An abnormal anterolateral ligament presented an odds ratio of 55 for high degrees of pivot shift. • ALL MRI abnormalities association with knee instability is independent from other internal knee injuries.

ACL surgical trends evolve in the last five years for young European surgeons: results of the survey among the U45 ESSKA members

PURPOSE

Although the outcomes of ACL reconstruction are generally satisfying, there are several patients who do not regain their pre-injury sporting level and suffer persistent symptoms. Orthopaedic practice has evolved significantly over the last five years to address these drawbacks. The aim of the present survey was to analyze the changes in the approach to ACL reconstruction among a population of young ESSKA surgeons dedicated to ACL surgery.

METHODS

The survey was uploaded on the ESSKA website and was accessible to members under the age of 45. The ESSKA society has 1035 U45 members involved in multiple aspects of Orthopaedic practice. One hundred and forty questionnaires were returned. Several aspects of ACL surgery were investigated at baseline and 5 years prior. They included general details such as the volume of ACL reconstructions per surgeon per year, the graft choice in cases of low and high demanding patients, the technique for femoral tunnel drilling and the preferred device for femoral fixation. The approach to the management of damage to peripheral structures, as well as meniscal ramp and root tears were also investigated.

RESULTS

Hamstrings and quadrupled semitendinosus were the preferred graft choice in low-demanding patients (92.9%) while quadriceps tendon is gaining popularity in contact sport practitioners (from 4.3 to 10.7%). The percentage of surgeons using femoral screws had decreased from 37.9 to 29.3 while the percentage of those who used buttons increased from 52.9 to 69.3%. Extra-articular procedures (antero-lateral ligament (ALL) or lateral tenodesis have become popular. The percentage of surgeons who perform an additional peripheral reconstruction rose from 28.5 to 71.5%. Of those who perform the meniscal repair more than 50% of patients rose from 14.3 to 27.9%. Similarly, the percentage of surgeons who performed a medial meniscus ramp lesion repair rose from 29.4 to 54.7%. While the percentage of those who choose to perform a transtibial pull-out repair of lateral meniscus root tears significantly rose from 17.9 to 59.3%.

CONCLUSIONS

The present survey among under 45 years old ESSKA surgeons yields some notable findings. The new evidence on the impact of injuries on peripheral structures and menisci is stimulating surgeons towards a more anatomic approach if identified at the time of ACL reconstruction. This evidence will probably influence future research and decision-making.

LEVEL OF EVIDENCE

IV.

Loading mechanisms of the anterior cruciate ligament

This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

Extent of posterolateral tibial plateau impaction fracture correlates with anterolateral complex injury and has an impact on functional outcome after ACL reconstruction

PURPOSE

The impact of posterolateral tibial plateau impaction fractures (TPIF) on posttraumatic knee stability in the setting of primary anterior cruciate ligament (ACL) tear is unknown. The main objective was to determine whether increased bone loss of the posterolateral tibial plateau is associated with residual rotational instability and impaired functional outcome after ACL reconstruction.

METHODS

A cohort was identified in a prospective enrolled study of patients suffering acute ACL injury who underwent preoperative standard radiographic diagnostics and clinical evaluation. Patients were included when scheduled for isolated single-bundle hamstring autograft ACL reconstruction. Exclusion criteria were concurrent anterolateral complex (ALC) reconstruction (anterolateral tenodesis), previous surgery or symptoms in the affected knee, partial ACL tear, multi-ligament injury with an indication for additional surgical intervention, and extensive cartilage wear. On MRI, bony (TPIF, tibial plateau, and femoral condyle morphology) and ligament status (ALC, concomitant collateral ligament, and meniscus injuries) were assessed by a musculoskeletal radiologist. Clinical evaluation consisted of KT-1000, pivot-shift, and Lachman testing, as well as Tegner activity and IKDC scores.

RESULTS

Fifty-eight patients were included with a minimum follow-up of 12 months. TPIF was identified in 85% of ACL injuries (n = 49). The ALC was found to be injured in 31 of 58 (53.4%) cases. Pearson analysis showed a positive correlation between TPIF and the degree of concomitant ALC injury (p < 0.001). Multiple regression analysis revealed an increased association of high-grade TPIF with increased lateral tibial convexity (p = 0.010). The high-grade TPIF group showed worse postoperative Tegner scores 12 months postoperatively (p = 0.035).

CONCLUSION

Higher degrees of TPIFs are suggestive of a combined ACL/ALC injury. Moreover, patients with increased posterolateral tibial plateau bone loss showed lower Tegner activity scores 12 months after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Anterolateral complex of the knee: State of the art

Rotatory instability of the knee represents the main reason for failure and poor clinical outcomes regarding anterior cruciate ligament (ACL) reconstruction techniques. It is now clear that the anterolateral complex (ALC) of the knee possesses a fundamental role, in association with the ACL, in controlling internal rotation. Over the past decade, ever since the anterolateral ligament has been identified and described as a distinct structure, there has been a renewed interest in the scientific community about the whole ALC: Lateral extra-articular tenodesis have made a comeback in association with ACL reconstructions to improve functional outcomes, reducing the risks of graft failure and associated injuries. Modern ACL reconstruction surgery must therefore investigate residual instability and proceed, when necessary, to extra-articular techniques, whether functional tenodesis or anatomical reconstruction.This review aims to investigate the latest anatomical and histological descriptions, and the role in rotational control and knee biomechanics of the ALC and its components. The diagnostic tools for its identification, different reconstruction techniques, and possible surgical indications are described.. In addition, clinical and functional results available in the literature are reported.

In vivo knee rotational stability 2 years after the ACL reconstruction using a quadriceps tendon graft with bone block and bone-patellar tendon-bone graft

INTRODUCTION

The aim of this prospective randomised study was to evaluate clinical results and rotational stability at least 2 years after single-bundle anatomic anterior cruciate ligament reconstruction using a quadriceps tendon graft with bone block (BT) and bone-patellar tendon-bone graft (BTB).

MATERIALS AND METHODS

In both groups (BT and BTB), 40 patients selected prospectively at random were evaluated. The mean follow-up after the surgery was 28 months (range 24-33 months). A navigation system was used to measure rotational stability of the knee joint. Cincinnati, Lysholm, and IKDC scores and visual analog score (VAS) were used to evaluate clinical results and the non-parametric Wilcoxon test was used for the statistical analysis.

RESULTS

After the BT reconstruction, the mean internal rotation of the tibia (IR) was 9.5°. In the contralateral healthy knee joint, IR was 8.6° at average. After the BTB reconstruction, the mean IR was 9.9°. In the contralateral healthy knee joint, IR was 8.7° at average. We did not find any statistically significant difference in IR stability between BT and BTB reconstruction. In terms of clinical results, regarding the VAS, patients perceive significantly more pain after the BTB reconstruction (p < 0.05). Kneeling was reported more difficult and painful after BTB reconstruction.

CONCLUSIONS

The BT reconstruction of the ACL provides similar clinical results, less pain, better flexion and the same rotational stability of the knee in comparison with the BTB reconstruction.

Complex Repair and Cruciate Ligament Reconstruction in KDs III and IV Multiligamentous Knee Injuries-Results of Mid-Term Follow-up

The purpose of the present study was to describe the longitudinal outcomes of acute repair of extra-articular structure and anatomical reconstruction of cruciate ligament for knee dislocations (KDs) III and IV multiligamentous knee injuries. Forty-seven patients with an acute KD III or IV were treated with one-stage management within 9.2 days. Forty-five KDs III and IV with a follow-up at a mean of 53.2 months were evaluated. The mean International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner score were 81.5 ± 0.7, 89.6 ± 1.2, and 6.8 ± 0.5, respectively. Comparing preoperative data with those at the latest follow-up, significant improvements in IKDC score (p < 0.01), Lysholm score (p < 0.01), and Tegner score (p < 0.01) were noted in all groups. Comparing contralateral knee stability, no statistical differences were found including the varus/valgus (0 degree/30 degrees) and Telos stress radiography. So, acute repair of extra-articular structure and anatomical reconstruction of cruciate ligament resulted in satisfactory outcomes for KDs III and IV multiligamentous knee injuries.

Effects of the Anterolateral Ligament and Anterior Cruciate Ligament on Knee Joint Mechanics: A Biomechanical Study Using Computational Modeling

Background:

Recent studies on lateral knee anatomy have reported the presence of a true ligament structure, the anterolateral ligament (ALL), in the anterolateral region of the knee joint. However, its biomechanical effects have not been fully elucidated.

Purpose:

To investigate, by using computer simulation, the association between the ALL and anterior cruciate ligament (ACL) under dynamic loading conditions.

Study Design:

Descriptive laboratory study; Level of evidence, 5.

Methods:

The authors combined medical imaging from 5 healthy participants with motion capture to create participant-specific knee models that simulated the entire 12 degrees of freedom of tibiofemoral (TF) and patellofemoral (PF) joint behaviors. These dynamic computational models were validated using electromyographic data, muscle activation data, and data from previous experimental studies. Forces exerted on the ALL with ACL deficiency and on the ACL with ALL deficiency, as well as TF and PF contact forces with deficiencies of the ACL, ALL, and the entire ligament structure, were evaluated under gait and squat loading. A single gait cycle and squat cycle were divided into 11 time points (periods 0.0-1.0). Simulated ligament forces and contact forces were compared using nonparametric repeated-measures Friedman tests.

Results:

Force exerted on the ALL significantly increased with ACL deficiency under both gait- and squat-loading conditions. With ACL deficiency, the mean force on the ALL increased by 129.7% under gait loading in the 0.4 period ( P < .05) and increased by 189% under high flexion during the entire cycle of squat loading ( P < .05). A similar trend of significantly increased force on the ACL was observed with ALL deficiency. Contact forces on the TF and PF joints with deficiencies of the ACL, ALL, and entire ligament structure showed a complicated pattern. However, contact force exerted on TF and PF joints with respect to deficiencies of ACL and ALL significantly increased under both gait- and squat-loading conditions.

Conclusion:

The results of this computer simulation study indicate that the ACL and the ALL of the lateral knee joint act as secondary stabilizers to each other under dynamic load conditions.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

Background

Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.

Methods

The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.

Results

ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient.

Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0–2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54–0.85) (p = 0.03) and an accuracy of 79%.

Conclusion

ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.

Study design

Cohort study; Level of evidence, 3.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05218-8.

Injuries to the anterolateral ligament are observed more frequently compared to lesions to the deep iliotibial tract (Kaplan fibers) in anterior cruciate ligamant deficient knees using magnetic resonance imaging

PURPOSE

To determine the accuracy of detection, injury rate and inter- and intrarater reproducibility in visualizing lesions to the anterolateral ligament (ALL) and the deep portion of the iliotibial tract (dITT) in anterior cruciate ligament (ACL) deficient knees.

METHODS

Ninety-one consecutive patients, out of those 25 children (age 14.3 ± 3.5 years), with diagnosed ACL tears were included. Two musculoskeletal radiologists retrospectively reviewed MRI data focusing on accuracy of detection and potential injuries to the ALL or dITT. Lesion were diagnosed in case of discontinued fibers in combination with intra- or peri-ligamentous edema and graded as intact, partial or complete tears. Cohen's Kappa and 95% confidence intervals (95% CI) were determined for inter- and intrarater reliability measures.

RESULTS

The ALL and dITT were visible in 52 (78.8%) and 56 (84.8%) of adult-and 25 (100%) and 19 (76.0%) of pediatric patients, respectively. The ALL was injured in 45 (58.5%; partial: 36.4%, compleate: 22.1%) patients. Partial and comleate tears, where visualized in 21 (40.4%) and 16 (30.8%) adult- and seven (28.0%) and one (4%) peditric patients. A total of 16 (21.3%; partial: 13.3%, compleate: 8.0%) dITT injuries were identified. Partal and complete lesions were seen in seven (12.5%) and five (8.9%) adult- and three (15.8%) and one (5.3%) pediatric patients. Combined injuries were visualized in nine (12.7%) patients. Inter-observer (0.91-0.95) and intra-observer (0.93-0.95) reproducibility was high.

CONCLUSION

In ACL injured knees, tears of the ALL are observed more frequently compared to lesions to the deep iliotibial tract. Combined injuries of both structures are rare. Clinically, the preoperative visualization of potentially injured structures of the anterolateral knee is crucial and is important for a more personalized preoperative planning and tailored anatomical reconstruction. The clinical implication of injuries to the anterolateral complex of the knee needs further investigation.

LEVEL OF EVIDENCE

II.

Arthroscopic Centralization for Lateral Meniscal Injuries Reduces Laxity in the Anterior Cruciate Ligament-Reconstructed Knee

BACKGROUND

A lateral meniscal (LM) disorder is one factor that causes rotational laxity after anterior cruciate ligament (ACL) reconstruction (ACLR). There are different types of irreparable meniscal disorders, one of which is a massive meniscal defect.

HYPOTHESIS/PURPOSE

The purpose of this study was to evaluate the kinematic effects of arthroscopic centralization on an irreparable LM defect. The hypothesis was that arthroscopic centralization for an irreparable LM defect with concomitant ACLR would improve knee rotational stability.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 14 fresh-frozen human cadaveric knees were tested in 4 states: (1) intact ACL and intact lateral meniscus, (2) reconstructed ACL and intact lateral meniscus, (3) reconstructed ACL and lateral meniscus defect, and (4) reconstructed ACL and centralized lateral meniscus. Anatomic ACLR was performed using an 8 mm-diameter hamstring tendon graft. An LM defect (20% of the anteroposterior length) was created arthroscopically, and arthroscopic centralization was performed. Kinematics were analyzed using a 6 degrees of freedom robotic system under 4 knee loads: (1) an 89.0-N anterior tibial load, (2) a 5.0-N·m external rotation tibial torque, (3) a 5.0-N·m internal rotation tibial torque, and (4) a simulated pivot-shift load with a combined 7.0-N·m valgus and 5.0-N·m internal rotation tibial torque.

RESULTS

LM centralization reduced anterior tibial translation similar to that of the ACLR intact LM state under anterior tibial loading (~2 mm at 30° of flexion) and showed 40% to 100% of tibial displacement in the 4 knee states under simulated pivot-shift loading. The procedure overconstrained the knee under internal rotation tibial torque and simulated pivot-shift loading.

CONCLUSION

Arthroscopic centralization reduced knee laxity after ACLR for a massive LM defect in a cadaveric model.

CLINICAL RELEVANCE

In cases involving irreparable LM injuries during ACLR, consideration should be given to arthroscopic centralization for reducing knee laxity. However, the procedure may overconstrain the knee in certain motions.

Increased lateral femoral condyle ratio is associated with greater risk of ALC injury in non-contact anterior cruciate ligament injury

PURPOSE

To examine whether increased lateral femoral condyle ratio (LFCR) correlates with increased risk of Anterior cruciate ligament (ACL) injury (1) and to evaluate the relationship between the LFCR and anterolateral complex (ALC) injury in non-contact ACL torn knees (2).

METHODS

Six hundred and seventy-two patients who underwent ACL reconstruction surgery between 2013 and 2019 were retrospectively reviewed, and 120 patients were finally included in the study. Forty patients (ACL + ALC injury) were included in the study group, while forty patients with isolated ACL injury (isolated ACL injury group) and 40 patients who suffered from meniscal tear without ACL or ALC injury were matched in a 1:1 fashion by age, sex, and BMI to the study group (ACL + ALC injury). The LFCR was measured on standard lateral radiographs in a blinded fashion. The differences between the three groups were analyzed by ANOVA. A ROC (Receiver Operating Characteristic) curve was produced to determine risk of ACL injury and risk of concomitant ALC injury in non-contact ACL injury.

RESULTS

The mean LFCR was 71.9% ± 3.1% in the ACL + ALC injury group, 68.4% ± 3.2% in the isolated ACL injury group, and 66.8% ± 2.6% in the control group (patients who suffered from meniscal tear without ACL or ALC injury). Significantly greater LFCR was found in the ACL + ALC injury group than that in the isolated ACL injury group (p < 0.017). Greater LFCR was additionally confirmed in the ACL injury group as compared to the control group (p < 0.05). ROC curve analysis demonstrated that LFCR > 68.3% was predictive for an increased risk of ACL injury in the entire cohort. LFCR > 69.4% was predictive for an increased risk of ALC injury in non-contact ACL ruptured patients.

CONCLUSION

Increased LFCR was found to be associated with greater risk of ALC injury in non-contact ACL ruptured patients. Additionally, increased LFCR was further confirmed to be correlated with increased risk of ACL injury in an Asian population. The data from this study may help recognize patients undergoing ACL reconstruction that could benefit from additional extra-articular tenodesis.

LEVEL OF EVIDENCE

III.

A Surgical Algorithm According to Pivot-Shift Grade in Patients With ACL Injury: A Prospective Clinical and Radiological Evaluation

Background:

Some patients have a positive pivot-shift finding and rotational instability after anterior cruciate ligament (ACL) reconstruction (ACLR). Three major pathologies known to affect the pivot-shift examination include ACL tear, anterolateral ligament injury, and loss of posterior lateral meniscus root function.

Purpose:

To describe a surgical algorithm determining indications for lateral extra-articular tenodesis (LET) based on intraoperative pivot-shift examination to prevent postoperative pivot shift and rotational instability and to evaluate the 2-year clinical and functional outcomes.

Study Design:

Case series; Level of evidence, 4.

Methods:

The study included 47 consecutive patients (39 men and 8 women) who underwent operative treatment for ACL injury between 2016 and 2017. Pivot-shift examination was performed under anesthesia, and the pivot shift was graded as grade 1 (glide), grade 2 (clunk), or grade 3 (gross). According to the surgical algorithm, single-bundle ACLR was performed in patients with grade 1 pivot shift. In patients with grade 2 with loss of posterior lateral meniscus root function, concurrent lateral meniscal repair was performed, and in patients with grade 2 with an intact lateral meniscus posterior root, concurrent extra-articular iliotibial band tenodesis was performed. Patients with grade 3 underwent ACLR, lateral meniscal repair, and LET. Clinical and radiographic evaluations were performed.

Results:

The mean age was 27.2 years (range, 16-56 years). In total, 26 (55.3%) patients were evaluated as having pivot-shift grade 1; 16 (34%) patients, grade 2; and 5 (10.6%) patients, grade 3. A total of 7 (14.9%) patients underwent LET in addition to ACLR. Two of these patients had pivot-shift grade 2, and LET was performed since the lateral meniscus posterior root was intact. In 14 of 16 patients with grade 2, lateral meniscus root disruption was detected, and lateral meniscal repair was performed. One patient was excluded from the further follow-up because of graft failure. At a mean postoperative follow-up of 29 months in 46 patients, the pivot-shift examination was negative in all patients. The mean Lysholm and International Knee Documentation Committee subjective scores were 95.35 ± 4.40 and 82.87 ± 9.36, respectively. Radiographic evidence of osteoarthritis was not detected.

Conclusion:

Only 14.9% of patients needed LET. With proper ACL, lateral meniscal, and anterolateral ligament surgery, it was possible to prevent positive pivot-shift findings postoperatively.

Combined Anterolateral and Anterior Cruciate Ligament Reconstruction Improves Pivot Shift Compared With Isolated Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

To perform a systematic review and meta-analysis of the literature on anterolateral ligament (ALL) reconstruction as it relates to techniques, biomechanical properties, and clinical outcomes.

METHODS

PubMed, OVID/Medline, and Embase were queried in July 2020. Data pertaining to (1) techniques, (2) biomechanical properties, and (3) clinical outcomes of ALL reconstruction were recorded. DerSimonian-Laird random-effects meta-analyses were performed for included randomized controlled trials comparing combined ALL/anterior cruciate ligament (ACL) reconstruction and isolated ACL reconstruction. Data from lower levels of evidence were described qualitatively, and when possible, outcomes were reported as ranges to avoid inappropriate pooling of data.

RESULTS

A total of 46 articles were identified. Sixteen were biomechanical studies, 16 were clinical outcome studies, and 14 were technique studies. Of the 16 biomechanical studies, the majority demonstrated that anterior translation, internal rotation, and pivot shift was restored with combined ACL/ALL reconstruction and superior to ACL reconstruction alone. Ten biomechanical studies reported on constraint: 4 noted overconstraint when the femoral attachment site was proximal and posterior to the lateral femoral condyle, whereas 1 reported laxity. ACL failure rates after combined ACL/ALL reconstruction ranged between 2.7% and 11.1%. The mean postoperative Lysholm score ranged between 58.7 and 98.0; mean postoperative International Knee Documentation Committee score between 57.8 and 96.3; and mean postoperative Tegner score between 4 and 8. Six outcomes were explored through meta-analysis, of which the mean difference in Lysholm scores (2.26, P < .001) and restoration of pivot shift (relative risk 1.1, P = .046) was found to favor combined ACL/ALL reconstruction.

CONCLUSIONS

Although indications for ALL reconstruction remain heterogeneous, contemporary evidence suggests that ALL reconstruction improves pivot shift and confers comparable clinical and functional outcomes with isolated ACLR.

LEVEL OF EVIDENCE

IV, systematic review and meta-analysis.

Increased Rotatory Laxity after Anterolateral Ligament Lesion in Anterior Cruciate Ligament- (ACL-) Deficient Knees: A Cadaveric Study with Noninvasive Inertial Sensors

The anterolateral ligament (ALL) has been suggested as an important secondary knee restrain on the dynamic laxity in anterior cruciate ligament- (ACL-) deficient knees. Nevertheless, its kinematical contribution to the pivot-shift (PS) phenomenon has not been clearly and objectively defined, and noninvasive sensor technology could give a crucial contribution in this direction. The aim of the present study was to quantify in vitro the PS phenomenon in order to investigate the differences between an ACL-deficient knee and an ACL+ALL-deficient knee. Ten fresh-frozen paired human cadaveric knees (n = 20) were included in this controlled laboratory study. Intact, ACL-deficient, and ACL+ALL-deficient knees were subjected to a manual PS test quantified by a noninvasive triaxial accelerometer (KiRA, OrthoKey). Kinematic data (i.e., posterior acceleration of the tibial lateral compartment) were recorded and compared among the three statuses. Pairwise Student's t-test was used to compare the single groups (p < 0.05). Intact knees, ACL-deficient knees, and ACL+ALL-deficient knees showed an acceleration of 5.3 ± 2.1 m/s², 6.3 ± 2.3 m/s², and 7.8 ± 2.1 m/s², respectively. Combined sectioning of ACL and ALL resulted in a statistically significant acceleration increase compared to both the intact state (p < 0.01) and the ACL-deficient state (p < 0.01). The acceleration increase determined by isolated ACL resection compared to the intact state was not statistically significant (p > 0.05). The ALL sectioning increased the rotatory laxity during the PS after ACL sectioning as measured through a user-friendly, noninvasive triaxial accelerometer.

High Rate of Initially Overlooked Kaplan Fiber Complex Injuries in Patients With Isolated Anterior Cruciate Ligament Injury

BACKGROUND

Injuries to the Kaplan fiber complex (KFC) are not routinely assessed for in the anterior cruciate ligament (ACL)-deficient knee during preoperative magnetic resonance imaging (MRI). As injuries to the KFC lead to anterolateral rotatory instability (ALRI) in the ACL-deficient knee, preoperative detection of these injuries on MRI scans may help surgeons to individualize treatment and improve outcomes, as well as to reduce failure rates.

PURPOSE

To retrospectively determine the rate of initially overlooked KFC injuries on routine MRI in knees with isolated primary ACL deficiency.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent isolated ACL reconstruction between August 2013 and December 2019 were identified. No patient had had Kaplan fiber (KF) injury identified on the initial reading of the MRI scan or at the time of surgery. Preoperative knee MRI scans (minimum 1.5 T) were reviewed and injuries to the proximal and distal KFs were recorded by 3 independent reviewers. KF length and distance to nearby anatomic landmarks (the lateral joint line and the lateral femoral epicondyle) were measured. Additional radiological findings, including bleeding, lateral femoral notch sign, and bone marrow edema (BME), were identified to detect correlations with KFC injury.

RESULTS

The intact KFC could reliably be identified by all 3 reviewers (85.9% agreement; Kappa, 0.716). Also, 53% to 56% of the patients with initially diagnosed isolated ACL ruptures showed initially overlooked injuries to the KFC. Injuries to the distal KFs were more frequent (48.1%, 53.8%, and 43.3% by the first, second, and third reviewers, respectively) than injuries to the proximal KFs (35.6%, 47.1%, and 45.2% by the first, second, and third reviewers, respectively). Bleeding in the lateral supracondylar region was associated with KFC injuries (P = .023). Additionally, there was a positive correlation between distal KF injuries and lateral tibial plateau BME (P = .035), but no associations were found with the lateral femoral notch sign or other patterns of BME, including pivot-shift BME.

CONCLUSION

KF integrity and injury can be reliably detected on routine knee MRI scans. Also, 53% to 56% of the patients presenting with initially diagnosed isolated ACL ruptures had concomitant injuries to the KFC. This is of clinical relevance, as ACL injuries diagnosed by current routine MRI examination protocols may come with a high number of occult or hidden KFC injuries. As injuries to the KFC contribute to persistent ALRI, which may influence ACL graft failure or reoperation rates, significant improvements in preoperative diagnostic imaging are required to determine the exact injury pattern and to assist in surgical decision making.

A Quantifiable Risk Factor for ACL Injury: Applied Mathematics to Model the Posterolateral Tibial Plateau Surface Geometry

Background:

The mechanism for traumatic ruptures of the native anterior cruciate ligament (ACL) is frequently a noncontact injury involving a valgus moment with internal rotation of the tibia. The abnormal rotation and translation of the lateral femoral condyle posteroinferiorly relative to the lateral tibial plateau is thought to be related to the geometry of the tibial plateau.

Purpose/Hypothesis:

The purpose of the study was to mathematically model the posterior tibial plateau geometry in patients with ACL injuries and compare it with that of matched controls. The hypothesis was that increased convexity and steepness of the posterior aspect of the lateral plateau would subject knees to higher forces, leading to a potentially higher risk of ACL injury.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

We mathematically modeled the posterior curvature of the lateral tibial plateau in 64 patients with ACL injuries and 68 matched controls. Using sagittal magnetic resonance imaging scans of the knee, points on the articular cartilage of the posterolateral tibial plateau were selected and curve-fitted to a power function (y = a × xⁿ). For coefficient a and coefficient n, both variables modulated the shape of the curve, where a larger magnitude represented an increase in slope steepness. Groups were compared using a Mann-Whitney test and α < .05.

Results:

There was a significant difference in surface geometry between the patients with ACL injuries and matched controls. The equation coefficients were significantly larger in the patients with ACL injuries: coefficient a (ACL injury, 0.9 vs control, 0.68; P < .0001) and coefficient n (ACL injury, 0.34 vs control, 0.30; P = .07). For coefficient a, there was a 78.9% sensitivity, 77.5% specificity, and odds ratio of 12.6 (95% CI, 5.5-29.0) for ACL injury using a cutoff coefficient a = .78.

Conclusion:

Patients with ACL injuries had a significantly greater posterolateral plateau slope. The steeper drop off may play a role in higher anterior translation forces, coupled with internal rotation torques on the knee in noncontact injury, which could increase ACL strain and predispose to ACL injury.

Knee laxity, lateral meniscus tear and distal femur morphology influence pivot shift test grade in ACL injury patients

PURPOSE

Although several factors have been considered to be associated with pivot shift test grade in ACL injured patients, a conclusion regarding which factors contribute to the pivot shift test grade has not been reached. The purpose of this study was to identify factors associated with preoperative pivot shift test grade.

METHODS

Three hundred and sixty-six consecutive patients who underwent ACL reconstruction in our hospital were enrolled in the study. Patients were divided into two groups on the basis of preoperative pivot shift test grade (Mild: grade 0-3, Severe: grade 4-6). First, 13 independent variables (age, gender, period from injury to surgery, hyperextension, KT measurement, contralateral side pivot shift test grade, medial and lateral tibial slope, lateral condyle length, lateral condyle height, distal femoral condyle offset, medial and lateral meniscus tear) were analyzed by one-way ANOVA and Chi-squared test. Binary Logistic regression was then performed based on the results of univariate analyses (independent variables of p < 0.2 were included).

RESULTS

Hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and KT measurement were identified as risk factors for preoperative pivot shift grade via logistic regression analysis.

CONCLUSION

The current study revealed that hyperextension, lateral meniscus tear, contralateral side pivot shift test grade, distal femoral condyle offset and anterior instability were associated with preoperative pivot shift grade. Patients with above factors that cannot be modified during surgery may need special consideration when ACL reconstruction is performed, as greater preoperative pivot shift has been proven to be a risk factor for residual pivot shift after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Objectifying the Pivot Shift Test

The pivot shift test is utilized for assessment of rotatory instability in the anterior cruciate ligament (ACL) deficient knee. There are multiple reports of the pivot shift maneuver, and there is a lack of consensus among clinicians as to a standardized maneuver. Measurement devices are a feasible option to evaluate rotatory knee instability, objectively or quantitatively. Traditionally, measurement systems have been invasive systems. More recently, electromagnetic system, inertial sensor, or imaging analysis systems, specifically with the utilization of a tablet computer, have emerged as noninvasive, and more importantly, validated options. It is important to recognize that anatomic structures other than the ACL contribute to rotatory knee stability. Addressing the tibial slope, anterolateral structures of the knee, specifically the iliotibial band, and menisci during ACL surgery may decrease residual pivot shift in an attempt to improve clinical outcomes and prevent reinjury. This review article describes the pivot shift maneuver, objective measurement tools, and clinical applications of the pivot shift test.

Truly Existing or Hyped up? Unravelling the Current Knowledge Regarding the Anatomy, Radiology, Histology and Biomechanics of the Enigmatic Anterolateral Ligament of the Knee Joint

Ever since its description, anterolateral ligament (ALL) of the knee joint remains as the hotspot of controversies. Though it has been described under various descriptions, the structure gained its limelight when it was christened as anterolateral ligament by Claes in 2013. The main reason for the controversies around it is the lack of concrete evidences regarding its attachments, morphology, biomechanical aspects and radiological appearance. Similarly the role of ALL in pivot shift phenomenon also remains as a point of debate. The advocates of ALL suggest that because of its ability to modulate internal rotation and attachment to the lateral meniscus, ALL contributes to the pivot shift phenomenon. Similarly, the orientation of ALL stands as the reason for varied documentation with respect to imaging techniques. With the growing body of evidence, it is imperative to fix our stand regarding the structure because, if found to be morphologically persistent, it can be used for concomitant anterolateral stabilization along with anterior cruciate ligament reinforcement surgeries. The present review tries to systematically review the anatomy, variations in classifications, descriptions, histology, radiology and biomechanical features of ALL. At the end of the review, we would like to find the answer for the question: Is ALL a distinct ligamentous structure located at the anterolateral aspect of the knee? What is the contribution of it to the tibial internal rotation stability?

Painful Palpation of the Tibial Insertion of the Anterolateral Ligament Is Concordant With Acute Anterolateral Ligament Injury

Background

The anterolateral ligament (ALL) has been shown to contribute to the rotational stability of the knee. However, no clinical sign specific to ALL injury has been described.

Purpose/Hypothesis

The primary aim of this study was to determine the concordance between pain elicited upon ALL palpation and ALL injury diagnosed by ultrasonography (US). The secondary aim was to look for a relationship between ALL injury and high-grade pivot shift. We hypothesized that an ALL lesion can be diagnosed clinically in an acute knee injury by palpating its tibial insertion.

Study Design

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

Methods

A total of 130 patients (89 men, 41 women; mean age, 27.2 ± 8.3 years) with an acute, isolated anterior cruciate ligament injury who were scheduled for ligament reconstruction were enrolled in this study. ALL palpation was carried out a mean 8.8 ± 3.2 days after injury. Preoperatively, ALL integrity was evaluated with US, and the pivot shift was determined under general anesthesia. The agreement between pain upon ALL palpation and ALL injury detected on US was determined by calculating the intraclass correlation coefficient (ICC), along with 95% CIs.

Results

Distal palpation of the ALL tibial insertion elicited pain in 67 (51.5%) patients, and upon US the ALL was found to be damaged in 64 (49.2%) patients. The agreement between pain over the ALL tibial insertion and the ALL being damaged on US was excellent (ICC, 0.801; 95% CI, 0.730-0.855). Moreover, the clinical test had excellent sensitivity (92%; 95% CI, 88%-97%) and specificity (88%; 95% CI, 82%-93%). The agreement between pain at the ALL distal insertion and the pivot shift was good (ICC, 0.654; 95% CI, 0.543-0.742), and ALL palpation had excellent diagnostic accuracy for identifying rotational instability (sensitivity, 88% [95% CI, 82%-93%]; specificity, 97% [95% CI, 94%-100%]).

Conclusion

Palpation of the ALL tibial insertion highly correlates with ultrasonographic evidence of an ALL injury in the context of an acute knee injury. This simple test should become part of our standard examination when evaluating patients with acute knee injuries.

MRI visibility of the anterolateral ligament and the deep structures of the iliotibial tract

Purpose

The visualization of potentially injured anatomical structures is crucial. Lately the anterolateral ligament (ALL) and the deep structures of the iliotibial tract (ITT) have been of increased clinical interest because of their role as important lateral stabilizers of the knee. The aim of this study was to assess the visibility of the ALL and the deep structures of the ITT using MRI. Good intra- and inter-observer reproducibility was hypothesized.

Methods

Knee MRI data from patients without ligamentous lesions were retrospectively analyzed by two radiologists at two time points using axial and coronal sequences. The visibility of the different parts of the ALL (femoral, meniscal and tibial part) and of the deep ITT, namely the deep attachments of the ITT to the distal femur and capsulo-osseous layer of the ITT, were determined on a binary (yes/no) basis.

Results

Seventy-one cases (42 men, 29 women) were studied. Inter-observer agreement was high. Cohen’s kappa was 0.97 for the tibial part of the ALL and 0.76 for the femoral part. For the deep attachments of the ITT to the distal femur Cohen’s kappa was 0.94. For each of the investigated parameters absolute agreement between the observers was at least 88%. Regarding intra-observer agreement Cohen’s kappa was 0.62 for the femoral part of the ALL and 0.85 for the tibial part of the ALL. For the deep attachments of the ITT to the distal femur Cohen’s kappa was 0.94. For each investigated parameter absolute agreement between the two time points was at least 83%.

Conclusions

The presence of the anterolateral structures of the knee can be determined with substantial inter- and intra-observer agreement using MRI examination. This is applicable for both the ALL and the deep ITT.

Level of evidence

Diagnostic study – Level III.

The Influences of Chronicity and Meniscal Injuries on Pivot Shift in Anterior Cruciate Ligament-Deficient Knees: Quantitative Evaluation Using an Electromagnetic Measurement System

PURPOSE

To investigate the influences of time from injury to surgery and meniscal injuries on knee rotational laxity in anterior cruciate ligament (ACL)-deficient knees using the electromagnetic system retrospectively.

METHODS

Ninety-four unilateral ACL-injured patients (44 male and 50 female, mean age: 27.3 ± 11.8 years) were included. The pivot-shift test was performed before ACL reconstruction, as was a quantitative evaluation using the electromagnetic system to determine tibial acceleration. Patients were divided into 4 groups according to the chronicity: group 1, within 3 months (22 patients); group 2, between 3 and 6 months (29 patients); group 3, between 6 and 12 months (23 patients); and group 4, more than 12 months (20 patients). The presence of meniscal injuries was examined arthroscopically.

RESULTS

The tibial acceleration was significantly greater in group 4. There was a positive correlation between tibial acceleration and the time from injury to surgery (r = 0.47, P = .02). In groups 1, 2 and 3, the tibial acceleration in patients with a lateral meniscal injury was significantly greater than in patients with a medial meniscal injury and without meniscal injury. When patients with lateral meniscal injury were excluded (leaving those with medial meniscus injury or without meniscal injury), group 4 had significantly greater accelerations than other groups.

CONCLUSIONS

In ACL-deficient knees, rotational laxity increased with time and the increased rotational laxity was evident more than 1 year after injury whereas it increased with concomitant lateral meniscal injuries within 1 year after injury.

LEVEL OF EVIDENCE

Ⅳ, diagnostic study of nonconsecutive patients.

Modified Iliotibial Band Tenodesis Is Indicated to Correct Intraoperative Residual Pivot Shift After Anterior Cruciate Ligament Reconstruction Using an Autologous Hamstring Tendon Graft: A Prospective Randomized Controlled Trial

BACKGROUND

The indications for the addition of anterolateral soft tissue augmentation to anterior cruciate ligament (ACL) reconstruction and its effectiveness remain uncertain.

PURPOSE

To determine if modified iliotibial band tenodesis (MITBT) can improve clinical outcomes and reduce the recurrence of ACL ruptures when added to ACL reconstruction in patients with a residual pivot shift.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Patients with a primary ACL rupture satisfying the following inclusion criteria were enrolled: first ACL rupture, involved in pivoting sports, skeletally mature, no meniscal repair performed, and residual pivot shift relative to the contralateral uninjured knee immediately after ACL reconstruction. Patients were randomized to group A (no further surgery) or group B (MITBT added) and were followed up for 2 years. The patient-reported outcome (PRO) measures used were the International Knee Documentation Committee (IKDC) score, Knee injury and Osteoarthritis Outcome Score (KOOS) subscale of sport/recreation (Sport/Rec), KOOS subscale of quality of life (QoL), Lysholm knee score (LKS), Tegner activity scale (TAS), recurrent ACL ruptures, or need for further surgery in either knee. Analysis of variance was used to compare PROs; the Wilcoxon test was used for the TAS; and the chi-square test was used for recurrence of ACL ruptures, meniscal injuries, and contralateral ACL ruptures (P < .05).

RESULTS

A total of 55 patients were randomized: 27 to group A (female:male ratio = 15:12; mean age, 22.3 ± 3.7 years) and 28 to group B (female:male ratio = 17:11; mean age, 21.8 ± 4.1 years). At 2-year follow-up, group A had a similar IKDC score (90.9 ± 10.7 vs 94.2 ± 11.2; respectively; P = .21), lower KOOS Sport/Rec score (91.5 ± 6.4 vs 95.3 ± 4.4, respectively; P = .02), similar KOOS QoL score (92.0 ± 4.8 vs 95.1 ± 4.3, respectively; P = .14), lower LKS score (92.5 ± 4.8 vs 96.8 ± 8.0, respectively; P = .004), lower TAS score (median, 7 [range, 7-9] vs 8 [range, 8-10], respectively; P = .03), higher rate of recurrence (14.8% vs 0.0%, respectively; P < .001), similar rate of meniscal tears (14.8% vs 3.6%, respectively; P = .14), and similar rate of contralateral ACL ruptures (3.7% vs 3.6%, respectively; P = .99) relative to group B.

CONCLUSION

The augmentation of ACL reconstruction with MITBT reduced the risk of recurrent ACL ruptures in knees with a residual pivot shift after ACL reconstruction and improved KOOS Sport/Rec, LKS, and TAS scores.

REGISTRATION

ACTRN12618001043224 (Australian New Zealand Clinical Trials Registry).

Anterolateral ligament reconstruction as an augmented procedure for double-bundle anterior cruciate ligament reconstruction restores rotational stability: Quantitative evaluation of the pivot shift test using an inertial sensor

PURPOSE

The purpose of this study was to investigate the biomechanical function of the anterolateral structures (ALS) of the knee regarding rotational stability, and to attempt to verify the effectiveness of anterolateral ligament (ALL) reconstruction concomitant with double-bundle anterior cruciate ligament (ACL) reconstruction by quantifying the pivot shift test (PST) using an inertial sensor.

METHODS

Six knees of the fresh-frozen cadavers were evaluated during the following phases: (1) [Intact]; (2) ACL-deficient [ACL-D]; (3) ACL-reconstructed [ACL-R]; (4) ACL-reconstructed + ALS-deficient [ACL-R + ALS-D]; and (5) combined ACL and ALL reconstructed [ACL-R + ALL-R]. We evaluated knee rotational instability during each phase using the PST. We used an inertial sensor to calculate tibial external rotational angular velocity (ERAV) and tibial acceleration. Data were analyzed using repeated-measures analysis of variance; statistical significance was accepted as P < 0.05.

RESULTS

Relative to [Intact], [ACL-D] caused a significant increase in ERAV and acceleration. However, there was no difference in these parameters between [ACL-R] and [Intact]. [ACL-R + ALS-D] increased ERAV significantly compared with [ACL-R], and there was a significant difference between ERAV during [ACL-R + ALS-D] and [Intact]. However, ERAV was significantly reduced during [ACL-R + ALL-R] compared with [ACL-R + ALS-D], and there was no significant difference in ERAV or acceleration between [ACL-R + ALL-R] and [Intact].

CONCLUSIONS

ALS controlled rotational instability in cooperation with the ACL in a cadaveric model. In cases of combined injury of ACL and ALS, concomitant ACL and ALL reconstruction may restore knee stability comparable with the intact state.

Triaxial accelerometer evaluation is correlated with IKDC grade of pivot shift

PURPOSE

The purpose of this study was to evaluate the correlation between tibial acceleration parameters measured by the KiRA device and the clinical grade of pivot shift. The secondary objective was to report the risk factors for pre-operative high-grade pivot shift.

METHODS

Two-hundred and ninety-five ACL deficient patients were examined under anesthesia. The pivot shift tests were performed twice by an expert surgeon. Clinical grading was performed using the International Knee Documentation Committee (IKDC) scale and tibial acceleration data was recorded using a triaxial accelerometer system (KiRA). The difference in the tibial acceleration range between injured and contralateral limbs was used in the analysis. Correlation coefficients were calculated using linear regression. Multivariate logistic regression was used to identify risk factors for high grade pivot shift.

RESULTS

The clinical grade of pivot shift and the side-to-side difference in delta tibial acceleration determined by KiRA were significantly correlated (r = 0.57; 95% CI 0.513-0.658, p < 0.0001). The only risk factor identified to have a significant association with high grade pivot shift was an antero-posterior side to side laxity difference > 6 mm (OR = 2.070; 95% CI (1.259-3.405), p = 0.0042).

CONCLUSION

Side-to-side difference in tibial acceleration range, as measured by KiRA, is correlated with the IKDC pivot shift grade in anaesthetized patients. Side-to-side A-P laxity difference greater than 6 mm is reported as a newly defined risk factor for high grade pivot shift in the ACL injured knee.

DIAGNOSTIC STUDY

Level II.

Biomechanical function of the anterolateral ligament of the knee: a systematic review

BACKGROUND

It has been suggested that the anterolateral ligament (ALL) is an important anterolateral stabilizer of the knee joint which functions to prevent anterolateral subluxation and anterior subluxation at certain flexion angles in the knee.

PURPOSE

To analyze and systematically interpret the biomechanical function of the ALL.

METHODS

An online search was conducted for human cadaveric biomechanical studies that tested function of the ALL in resisting anterolateral subluxation and anterior subluxation of the knee. Two reviewers independently searched Medline, Embase, and the Cochrane Database of Systematic Reviews for studies up to 25 September 2018. Biomechanical studies not reporting the magnitude of anterior tibial translation or tibial internal rotation in relation to the function of the ALL were excluded.

RESULTS

Twelve biomechanical studies using human cadavers evaluating parameters including anterior tibial translation and/or internal tibial rotation in anterior cruciate ligament (ACL)-sectioned and ALL-sectioned knees were included in the review. Five studies reported a minor increase or no significant increase in anterior tibial translation and internal tibial rotation with further sectioning of the ALL in ACL-deficient knees. Five studies reported a significant increase in knee laxity in tibial internal rotation or pivot shift with addition of sectioning the ALL in ACL-deficient knees. Two studies reported a significant increase in both anterior tibial translation and internal tibial rotation during application of the anterior-drawer and pivot-shift tests after ALL sectioning.

CONCLUSION

There was inconsistency in the biomechanical characteristics of the ALL of the knee in resisting anterolateral and anterior subluxation of the tibia.

Ultrastructural Assessment of the Anterolateral Ligament

Background:

The anterolateral ligament (ALL) has been identified as a structure on the lateral side of the knee, but debate exists regarding whether it is a capsular thickening or a ligament.

Hypothesis:

A detailed ultrastructural characterization of the ALL and its ultrastructure collagen arrangement will reveal it more closely resembles ligamentous tissue than joint capsule.

Study Design:

Descriptive laboratory study.

Methods:

Eight paired knee samples from 4 fresh-frozen male cadavers were used for this study. Samples were harvested from the ALL, the joint capsule, and the medial collateral ligament (MCL). All samples were evaluated with light microscopy (LM), transmission electron microscopy (TEM), and variable pressure scanning electron microscopy (VP-SEM). With LM, the 3 tissues were analyzed and their morphology described. With TEM, the ultrastructure and collagen characteristics were quantified and compared among specimens. Then, the 3-dimensional characteristics were compared with VP-SEM.

Results:

Ultrastructure analysis demonstrated similar morphology between the ALL and MCL, with significant differences in these 2 structures as compared with the joint capsule. On LM, the ALL and MCL were characterized by the presence of a dense collagen fiber oriented in the longitudinal and transversal directions of the fiber bundles, while the joint capsule was found to have a more disorganized architecture. On TEM, the collagen fibers of the ALL and MCL demonstrated similar ultrastructural morphology, with both having collagen fibers in parallel, longitudinal alignment. A quantitative analysis was also performed, with the mean (± SD) diameter of fibrils in the ALL and MCL being 80 ± 2.66 nm and 150 ± 3.35 nm, respectively (all P < .001). The VP-SEM highlighted that ALL and MCL morphology demonstrated arrangements of fiber bundles that are densely packed and organized, in contrast to the disorganized fibers of the joint capsule.

Conclusion:

The ALL and MCL have comparable ultrastructures that are distinctly different from the joint capsule, as visualized on LM, TEM, and VP-SEM.

Clinical Relevance:

The ALL should be considered a distinctive structure of the knee, although strictly connected to the surrounding capsule.

MRI-determined anterolateral capsule injury did not affect the pivot-shift in anterior cruciate ligament-injured knees

PURPOSE

The purpose of this study was to quantitatively compare the results of pivot-shift test between knees with anterior cruciate ligament (ACL) injury with and without anterolateral capsule (ALC) injury detected on MRI. ALC injury was hypothesized to worsen rotatory knee laxity.

METHODS

82 patients with unilateral ACL injury were enrolled in this study. The pivot-shift test was performed under anesthesia before ACL reconstruction. Two evaluations were conducted simultaneously: IKDC clinical grading and the quantitative evaluation using an electromagnetic measurement system that determined tibial acceleration (m/s²). Two examiners identified the ALC injury on magnetic resonance imaging (MRI) and stratified patients into two groups: ALC-injured (ALC+) and ALC-intact (ALC-). ALC injury was diagnosed if the signal intensity on coronal T2-weighted sequences is increased. After confirming the reliability of the MRI, the difference in the pivot-shift between two groups was assessed.

RESULTS

Because of the poor agreement between examiners with respect to the ALC evaluations (κ coefficient of 0.25 and 58.5% concordance), the result from each examiner was analyzed separately. Examiner 1 found ALC injury in 42/82 knees (51%). The two groups had similar clinical grading (glide/clunk/gross: ALC+ group 21/18/3cases vs. ALC- group 21/16/3cases) (n.s.). Tibial acceleration during pivot-shift was also similar in the ALC+ (1.4 ± 1.2 m/s²) and ALC- (1.7 ± 1.3 m/s²) groups (n.s.). Examiner 2 found ALC injury in 28/82 knees (34%). Differences in clinical grading were not observed (glide/clunk/gross: ALC+ group 16/9/3 vs. ALC- group 26/25/3) (n.s.). However, the tibial acceleration in the ALC+ group (1.2 ± 0.8 m/s²) was significantly lower than that in the ALC- group (1.7 ± 1.3 m/s², p = 0.03).

CONCLUSION

Concomitant ALC injury in knees with ACL injury was not consistently detected on MRI and did not affect rotatory knee laxity.

LEVEL OF EVIDENCE

Case-control study, level III.

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect

PURPOSE

The aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL-reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL-reconstructed knee.

METHODS

Twelve fresh-frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.0 N anterior tibial load; (b) 4.0 N m internal and external rotational torques. Anatomic single-bundle ACL reconstruction with a 7 mm-diameter bovine extensor tendon graft was performed. A massive, middle segment, lateral meniscus defect was created via arthroscopy, and arthroscopic centralization was performed with a 1.4 mm anchor with a #2 suture. The LM states with ACL reconstruction evaluated were: intact, massive middle segment defect and with the lateral meniscus centralization procedure.

RESULTS

The rotation of the ACL reconstructed knee with the lateral meniscus defect was significantly higher than with the centralized lateral meniscus under an external rotational torque at 30° of knee flexion, and under an internal rotational torque at 30° and 45° of knee flexion. There were no systematic and consistent effects of LM centralization under anterior tibial translation.

CONCLUSIONS

In this porcine model, the capsular support of middle segment of the lateral meniscus using arthroscopic centralization improved the residual rotational laxity of the ACL-reconstructed knee accompanied with lateral meniscus dysfunction due to massive meniscus defect. This study quantifies the benefit to knee kinematics of arthroscopic centralization by restoring the lateral meniscal function.

Anterolateral ligament injury has a synergic impact on the anterolateral rotatory laxity in acute anterior cruciate ligament-injured knees

PURPOSE

To investigate the prevalence of the anterolateral ligament (ALL) injuries and its role in rotatory laxity in acute anterior cruciate ligament (ACL)-injured knees.

METHODS

Two-hundred and ninety-six consecutive patients with acute ACL injuries were evaluated retrospectively, excluding those with other ligament injury and undetectable path of ALL in MRI. Patients were divided into two groups based on the degree of ACL injury in arthroscopy (complete versus partial group). Logistic regression and discriminant analysis were performed to assess the risk of pivot shift test.

RESULTS

A total of 169 patients were included (128 with complete and 41 with partial ACL rupture). Overall, 106/169 (62.7%) of ALL injuries were characterized, 87/128 (67.9%) in complete group, and 19/41 (46.3%) in partial group. The incidence of pivot shift was 120/128 (93.8%) and 14/41 (34.1%) in the complete and partial groups, respectively. The odds ratio in the pivot shift of combined ALL injury was found as 3.8 (95% CI 1.8-8.4) with the overall ACL injury, but higher as 17.1 (95% CI 3.1-96.4) with partial group. Higher grade of pivot shift showed a greater incidence of injury of ALL. Degree of ACL injury and ALL injury allowed 87.0% of correct classification of subsequent anterolateral rotatory laxity.

CONCLUSION

Injury to the ALL could have a synergetic effect on anterolateral rotatory laxity in acute ACL-injured knee, however, its effect might be minor in case of complete tear. Careful assessment about combined ALL injury should be considered, especially in knees with high-grade pivot shift in acute ACL-injured knees.

LEVEL OF EVIDENCE

Retrospective prognostic study, Level IV.

Distal femur morphology affects rotatory knee instability in patients with anterior cruciate ligament ruptures

PURPOSE

Distal femur morphology has been shown to influence knee joint kinematics and may affect rotatory knee laxity. The purpose of this study was to determine the relationship between rotatory knee laxity and distal femoral morphology in patients with complete anterior cruciate ligament (ACL) rupture. It was hypothesized that increased posterior femoral condylar depth on standard lateral radiographs, quantified as the "lateral femoral condyle ratio" would correlate with increased rotatory knee laxity, measured by a quantitative pivot shift test.

METHODS

Consecutive patients who underwent ACL reconstruction from 2014 to 2016 were retrospectively reviewed. A standardized pivot shift test was performed preoperatively on both knees and quantified using tablet technology. Using standard lateral radiographs of the knee, the ratio of posterior condylar distance over total condylar distance was defined as the lateral femoral condyle ratio.

RESULTS

Data sets were obtained for 57 patients. The mean anterior translation of the lateral knee compartment during a quantitative pivot shift test was found to be 4.0 ± 2.4 mm and 1.3 ± 0.9 mm for the injured and uninjured knees, respectively. The mean lateral femoral condyle ratio on X-ray was 63.2 ± 4.5%. There were significant correlations between the lateral femoral condyle ratio and the absolute quantitative (ρ = 0.370, p < 0.05) and side-to-side differences in anterior translation of the lateral knee compartment (ρ = 0.419, p < 0.05).

CONCLUSION

The most important finding from this study is that increased posterior femoral condylar depth, quantified as a lateral femoral condyle ratio, is associated with increased rotatory knee laxity in ACL-deficient patients. This suggests that distal femur morphology may influence rotatory knee laxity. This study may assist clinicians in evaluating ACL injuries and identifying patients at greater risk for persistent increased rotatory knee laxity after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Identification of Normal and Injured Anterolateral Ligaments of the Knee: A Systematic Review of Magnetic Resonance Imaging Studies

PURPOSE

To identify the normal and injured magnetic resonance imaging appearance of the anterolateral ligament (ALL).

METHODS

A systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed and Cochrane Library electronic databases were used to search for studies that reported the imaging outcomes of the appearance of the ALL. Two authors performed the searches in duplicate up to April 30, 2018, and interobserver agreement was calculated. The methodologic quality of included articles was assessed using an adaptation of the Arrivé methodologic quality scale for clinical studies of radiologic examinations.

RESULTS

From the original 270 records, a total of 24 studies (κ = 0.94) comprising 2,427 knees in 2,388 patients (mean age, 33.3 years; 66% male patients; 63% with anterior cruciate ligament [ACL] injury) were included. The ALL appeared in 51% to 100% of all assessed knees (71%-100% in ACL-injured knees and 64%-97% in uninjured knees) and was injured in 11% to 79% of ACL-injured knees. Reliability rates varied considerably (0.04-1.0 for intraobserver and 0.143-1.0 for interobserver agreement), and the entire portion of the ligament was often not seen. The tibial insertion was seen in 21% to 96% of cases, followed by the meniscal (range, 0%-100%) and femoral (range, 0%-90%) insertions. The mean methodologic quality score was 5.1 ± 1.8 out of a possible score of 9.

CONCLUSIONS

High variability was found in the identification of normal and injured ALL definition methods and the respective magnetic resonance imaging findings. Reliability rates varied considerably, and the entire portion of the ligament was often not seen.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to IV studies.

Editorial Commentary: Magnetic Resonance Imaging of the Knee Anterolateral Ligament: Does It Really Matter?

Great interest remains in the structures of the knee anterolateral complex and how they work synergistically with the anterior cruciate ligament to control anterolateral rotatory laxity. Many studies have now used magnetic resonance imaging to assess the degree of damage to the anterolateral ligament. The systematic review described in this commentary rigorously highlights the many deficiencies that exist within our current understanding of the imaging analysis of these structures. Marked variability in the definition of anterolateral ligament injury, significant methodological differences, and the lack of a gold standard reference make it very challenging to translate the findings of these imaging studies into clinical practice. More information is required to fully understand the injury pattern, and then clinical studies are needed to guide treatment. Hopefully we will then have the ability to better treat our patients with these challenging complex laxity patterns that exist over and above an isolated anterior cruciate ligament injury.