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

Correlation of Magnetic Resonance Imaging With Knee Anterolateral Ligament Anatomy: A Cadaveric Study

BACKGROUND

Anatomic and magnetic resonance imaging (MRI) studies have recently characterized the knee anterolateral ligament (ALL). So far, no study has focused on confirming whether the evaluated MRI parameters truly correspond with ALL anatomy.

PURPOSE

To assess the validity of MRI in detecting the ALL using an anatomic evaluation as reference.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 13 cadaveric knees were subjected to MRI and then to anatomic dissection. Dissection was performed according to previous anatomic study methodology. MRIs were performed with a 0.6- to 1.5-mm slice thickness and prior saline injection. The following variables were analyzed: distance from the origin of the ALL to the origin of the lateral collateral ligament (LCL), distance from the origin of the ALL to its bifurcation point, maximum length of the ALL, distance from the tibial insertion of the ALL to the articular surface of the tibia, ALL thickness, and ALL width. The 2 sets of measurements were analyzed using the Spearman correlation coefficient (ρ) and Bland-Altman plots.

RESULTS

The ALL was clearly observed in all dissected knees and MRI scans. It originated anterior and distal to the LCL, close to the lateral epycondile center, and showed an anteroinferior path toward the tibia, inserting between the Gerdy tubercle and the fibular head, around 5 mm under the lateral plateau. The ρ values tended to increase together for all studied variables between the 2 methods, and all were statistically significant, except for thickness (P = .077). Bland-Altman plots showed a tendency toward a reduction of ALL thickness and width by MRI compared with anatomic dissection.

CONCLUSION

MRI scanning as described can accurately assess the ALL and demonstrates characteristics similar to those seen under anatomic dissection.

CLINICAL RELEVANCE

MRI can accurately characterize the ALL in the anterolateral region of the knee, despite the presence of structures that might overlap and thus cause confusion when making assessments based on imaging methods.

Characterization of the anatomy of the anterolateral ligament of the knee using magnetic resonance imaging

OBJECTIVE

The anterolateral ligament (ALL) may limit tibial internal rotation and pivot-shift following anterior cruciate ligament reconstruction. Previous studies, using magnetic resonance imaging (MRI) to identify this structure, have been inconsistent. We aimed to further characterize the anatomy of this ligament with reference to previous work.

MATERIALS AND METHODS

Institutional Review Board approval was gained and a retrospective study of 154 consecutive 1.5-T MRI studies was performed by a consultant musculoskeletal radiologist. Cases with a lateral compartment or cruciate injury and patients under 16 years were excluded. A total of 100 MRIs (98 patients; 63 males: 35 females; mean age, 45.3 years, range, 16-85 years) were included in the study.

RESULTS

The ALL was visualized partially in 94 (94.0%) of the cases and fully with distinct femoral and tibial fibers in 57 (57.0%) of the cases. Although the femoral origin was discreet in only 57 (57.0%) of cases, the tibial insertion (7.64 ± 1.26 mm below the joint-line) and meniscal attachment were demonstrated in all cases where the ligament was seen. Where the femoral origin was not seen, a broad expansion of the ligament was noted. We identified four types of meniscal attachment (complete, central, bipolar, and inferior-only). The thickness of the ALL, at the level of the joint-line, was 1.75 ± 0.57 mm.

CONCLUSIONS

The ALL is a consistent structure with meniscal and tibial portions identifiable in the majority of MRI studies of the uninjured knee. There is an attachment to the lateral meniscus with anatomical variation described by our subclassification.

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament

PURPOSE

The purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics.

METHODS

Three different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation.

RESULTS

The ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role.

CONCLUSION

From this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics.

Anterolateral rotatory instability of the knee

Recent publications have generated renewed interest in the anatomy of the anterolateral capsule. Knowledge of the biomechanical function of the anterolateral components is lacking. Further research is required to evaluate the influence of the anterolateral capsule on rotatory laxity of the knee. The role of surgical procedures, such as an extra-articular tenodesis or lateral plasty, has to be defined based on quantification of the injury. This article seeks to summarize the current literature and discusses the role of the anterolateral capsule and reconstructive techniques in combined ligamentous knee trauma. Level of evidence V.

Anatomic Single-Graft Anterior Cruciate Ligament Reconstruction Restores Rotational Stability: A Robotic Study in Cadaveric Knees

PURPOSE

First, we aimed to investigate the ability of a single bone-patellar tendon-bone graft placed in the anatomic center of the femoral and tibial attachment sites to restore normal tibiofemoral compartment translations and tibial rotation. Second, we aimed to investigate what combination of anterior load and internal rotation torque applied during a pivot-shift test produces maximal anterior tibiofemoral subluxations.

METHODS

We used a 6-df robotic simulator to test 10 fresh-frozen cadaveric specimens under anterior cruciate ligament (ACL)-intact, ACL-sectioned, and ACL-reconstructed conditions measuring anterior translations of the medial, central, and lateral tibiofemoral compartments and degrees of tibial rotation. Specimens were loaded under Lachman, anterior limit, and internal rotation conditions, as well as 3 different pivot-shift conditions.

RESULTS

On ACL sectioning, compartment translations in the Lachman and 3 pivot-shift tests increased significantly and were restored to ACL-intact values after single-graft ACL reconstruction. In the pivot-shift tests, the single graft restored lateral and medial compartment translations (e.g., group 3, within 1.3 ± 0.6 mm and 0.8 ± 0.6 mm, respectively, of the ACL-intact state and internal rotation within 0.7° ± 1.2°). Anterior subluxation of the medial compartment during pivot-shift loading was reduced when internal rotation torque was increased from 1 to 5 Nm (P < .0001).

CONCLUSIONS

A single-graft ACL reconstruction performed at the central femoral and tibial ACL attachment sites restored anterior-posterior translation and tibial rotation motion limits. In addition, rotational knee stability as defined by tibiofemoral compartment translations was restored under all simulated pivot-shift testing conditions.

CLINICAL RELEVANCE

This study provides in vitro evidence to support the clinical use of single-graft ACL reconstructions in restoring tibiofemoral compartment translations. It also shows the advantage of describing ACL insufficiency in terms of medial and lateral compartment subluxations as compared with the common approach of describing changes in central tibial translations and rotations.

Length Changes of the Anterolateral Ligament During Passive Knee Motion: A Human Cadaveric Study

BACKGROUND

Persistent rotatory instability after anterior cruciate ligament (ACL) reconstruction may be a result of unaddressed insufficiency of the anterolateral structures. Recent publications about the anatomy of the anterolateral ligament (ALL) have led to a renewed interest in lateral extra-articular procedures, and several authors have proposed ALL reconstruction to supplement intra-articular ACL reconstruction. However, only limited knowledge about the biomechanical characteristics of the ALL exists.

PURPOSE/HYPOTHESIS

The purpose of this study was to analyze length changes of the ALL during passive knee motion. The study hypothesis was that the ALL lengthens with knee flexion and internal tibial rotation.

STUDY DESIGN

Controlled laboratory study.

METHODS

The ALL of 6 cadaveric knees was dissected. Specimens were mounted in a specifically designed test rig that allowed unconstrained passive flexion/extension movement between 0° and 90° as well as external/internal tibial rotation of 25° at various flexion angles. Highly elastic, capacitive polydimethylsiloxane strain gauges were attached to the insertion sites of the ALL. Length changes were recorded continuously at flexion angles between 0° and 90° and during internal/external tibial rotation at 0°, 15°, 30°, 45°, 60°, 75°, and 90°. All measurements were calculated as the relative length change (%) of the ALL compared with 0° of flexion and neutral rotation.

RESULTS

The mean relative length of the ALL significantly increased with increasing knee flexion (P < .001), with an estimated mean length change of +0.15% per degree. Both internal and external tibial rotation were independent determinants for length change; internal rotation significantly increased the length of the ALL (P < .001), whereas external rotation significantly decreased its length (P < .001). The mean length change with internal rotation increased with knee flexion, with a significantly greater length change at 90° compared with 0° (P = .048), 15° (P = .033), and 30° (P = .015). The maximum mean length change was +33.77% ± 9.62%, which was observed at 25° of internal rotation and 90° of flexion.

CONCLUSION

The ALL is a nonisometric structure that tensions with knee flexion and internal tibial rotation. Length changes with internal rotation were greater at higher flexion angles, with the greatest length change of the ALL observed at 90° of flexion.

CLINICAL RELEVANCE

The ALL can be considered a stabilizer against internal tibial rotation, especially at deep flexion angles. With regard to ALL reconstruction procedures, tensioning and fixation of the graft should be performed near 90° of flexion because graft tensioning near extension may cause excessive ligament strain with increasing knee flexion.

Does Combined Intra- and Extraarticular ACL Reconstruction Improve Function and Stability? A Meta-analysis

BACKGROUND

ACL reconstruction aims to restore knee function and stability; however, rotational stability may not be completely restored by use of standard intraarticular reconstruction alone. Although individual studies have not shown the superiority of combined ACL reconstruction compared with isolated intraarticular reconstruction in terms of function and stability, biomechanical principles suggest a combined approach may be helpful, therefore pooling (meta-analyzing) the available randomized clinical studies may be enlightening.

QUESTIONS/PURPOSES

We performed a meta-analysis to determine whether combining extraarticular with intraarticular ACL reconstruction would lead to: (1) similar knee function measured by the IKDC evaluation, return-to-activity, and Tegner Lysholm scores, compared with isolated intraarticular reconstruction; (2) increased stability measured by pivot shift and instrumented Lachman examination; and (3) any differences in complications and adverse events?

METHODS

To identify randomized controlled trials (RCTs) comparing combined intra- and extrarticular ACL reconstruction (combined reconstruction) with intraarticular ACL reconstruction only, we searched MEDLINE, EMBASE, SPORTDiscus, Latin American and Caribbean Health Sciences (LILACS), and the Cochrane Central Register of Controlled Trials, and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The main outcomes we sought were patient function and stability and complications after ACL reconstruction. Of 386 identified studies, eight RCTs were included (n=682 participants; followup, 12-84 months; men to women ratio, 2.17:1) in our meta-analysis. Study quality (internal validity) was assessed using the Cochrane risk-of-bias tool; in general, we found a moderate quality of evidence of the included studies.

RESULTS

When functional outcomes were compared, we found no difference between patients who underwent intraarticular ACL reconstruction only and those who underwent combined reconstruction (IKDC, return-to-activity, and Tegner Lysholm scores). However, patients who underwent combined reconstruction were more likely to show improved stability based on the pivot shift test (risk ratio [RR], 0.95; 95% CI, 0.91-0.99; p=0.02) and Lachman test (RR, 0.93; 95% CI, 0.88-0.98; p=0.01). In addition, our meta-analysis found no difference between the two treatments in terms of general complications or adverse events (RR, 1.31; 95% CI, 0.70-2.34; p=0.40) and the proportion of patients whose reconstructions failed (RR, 2.88; 95% CI, 0.73-11.47; p=0.13).

CONCLUSION

Combined intra- and extraarticular ACL reconstruction provided marginally improved knee stability and comparable failure rates but no difference in patient-reported functional outcomes scores. Complications and adverse events such as knee stiffness may be underreported and technical factors such as graft placement were difficult to evaluate. Future studies are needed to determine whether the small differences in additional stability warrant the potential morbidity of the additional extraarticular procedure and to determine long-term failure rates.

Isolated lateral collateral ligament complex injury in rock climbing and Brazilian Jiu-jitsu

We report two occurrences of high-grade tears of the lateral collateral ligament complex (LCLC), consisting of the anterolateral ligament (ALL) and fibular collateral ligament (FCL). One injury occurred in a rock climber and the other in a martial artist. Increasing awareness of isolated injuries of the LCLC will allow for appropriate diagnosis and management. We review and discuss the anatomy of the LCLC, the unique mechanism of isolated injury, as well as physical and imaging examination findings.

Anterolateral Ligament of the Knee: Back to the Future in Anterior Cruciate Ligament Reconstruction

Although the importance of the anterolateral stabilizing structures of the knee in the setting of anterior cruciate ligament (ACL) injuries has been recognized since many years, most of orthopedic surgeons do not take into consideration the anterolateral structures when performing an ACL reconstruction. Anatomic single or double bundle ACL reconstruction will improve knee stability, but a small subset of patients may experience some residual anteroposterior and rotational instability. For this reason, some researchers have turned again towards the anterolateral aspect of the knee and specifically the anterolateral ligament. The goal of this review is to summarize the existing knowledge regarding the anterolateral ligament of the knee, including anatomy, histology, biomechanics and imaging. In addition, the most common anterolateral reconstruction/tenodesis techniques are described together with their respective clinical outcomes.

Evaluation of the anterolateral ligament of the knee by means of magnetic resonance examination

OBJECTIVE

To evaluate the presence of the anterolateral ligament (ALL) of the knee in magnetic resonance imaging (MRI) examinations.

METHODS

Thirty-three MRI examinations on patients' knees that were done because of indications unrelated to ligament instability or trauma were evaluated. T1-weighted images in the sagittal plane and T2-weighted images with fat saturation in the axial, sagittal and coronal planes were obtained. The images were evaluated by two radiologists with experience of musculoskeletal pathological conditions. In assessing ligament visibility, we divided the analysis into three portions of the ligament: from its origin in the femur to its point of bifurcation; from the bifurcation to the meniscal insertion; and from the bifurcation to the tibial insertion. The capacity to view the ligament in each of its portions and overall was taken to be a dichotomous categorical variable (yes or no).

RESULTS

The ALL was viewed with signal characteristics similar to those of the other ligament structures of the knee, with T2 hyposignal with fat saturation. The main plane in which the ligament was viewed was the coronal plane. Some portion of the ligament was viewed clearly in 27 knees (81.8%). The meniscal portion was evident in 25 knees (75.7%), the femoral portion in 23 (69.6%) and the tibial portion in 13 (39.3%). The three portions were viewed together in 11 knees (33.3%).

CONCLUSION

The anterolateral ligament of the knee is best viewed in sequences in the coronal plane. The ligament was completely characterized in 33.3% of the cases. The meniscal portion was the part most easily identified and the tibial portion was the part least encountered.

Evaluation of the Length and Isometric Pattern of the Anterolateral Ligament With Serial Computer Tomography

BACKGROUND

Recent anatomical studies have identified the anterolateral ligament (ALL). Injury to this structure may lead to the presence of residual pivot shift in some reconstructions of the anterior cruciate ligament. The behavior of the length of this structure and its tension during range of motion has not been established and is essential when planning reconstruction.

PURPOSE

To establish differences in the ALL length during range of knee motion.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten unpaired cadavers were dissected. The attachments of the ALL were isolated. Its origin and insertion were marked with a 2 mm-diameter metallic sphere. Computed tomography scans were performed on the dissected parts under extension and 30°, 60°, and 90° of flexion; measurements of the distance between the 2 markers were taken at all mentioned degrees of flexion. The distances between the points were compared.

RESULTS

The mean ALL length increased with knee flexion. Its mean length at full extension and at 30°, 60°, and 90° of flexion was 37.9 ± 5.3, 39.3 ± 5.4, 40.9 ± 5.4, and 44.1 ± 6.4 mm, respectively. The mean increase in length from 0° to 30° was 3.99% ± 4.7%, from 30° to 60° was 4.20% ± 3.2%, and from 60° to 90° was 7.45% ± 4.8%. From full extension to 90° of flexion, the ligament length increased on average 16.7% ± 12.1%. From 60° to 90° of flexion, there was a significantly higher increase in the mean distance between the points compared with the flexion from 0° to 30° and from 30° to 60°.

CONCLUSION

The ALL shows no isometric behavior during the range of motion of the knee. The ALL increases in length from full extension to 90° of flexion by 16.7%, on average. The increase in length was greater from 60° to 90° than from 0° to 30° and from 30° to 60°. The increase in length at higher degrees of flexion suggests greater tension with increasing flexion.

CLINICAL RELEVANCE

Knowledge of ALL behavior during the range of motion of the knee will allow for fixation (during its reconstruction) to be performed with a higher or lower tension, depending on the chosen degree of flexion.

"Anatomic" single-bundle anterior cruciate ligament reconstruction reduces both anterior translation and internal rotation during the pivot shift

BACKGROUND

The ability of single-bundle anterior cruciate ligament (ACL) reconstruction to restore rotational control has been questioned by proponents of the double-bundle technique. The term anatomic positioning has become popularized in recognition of the incorrect positioning sometimes used in the past, which may have contributed to the lack of rotation control. The pivot-shift test remains the most clinically useful measure of ACL deficiency, and it is now possible to measure it both accurately and objectively using computer navigation.

HYPOTHESIS

Single-bundle ACL reconstruction will reduce anterior translation and internal rotation of the tibia during the pivot-shift test when compared with the contralateral uninjured knee.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 20 patients with an acute isolated ACL rupture underwent reconstruction with a single-bundle autologous hamstring graft. Computer navigation was used intraoperatively to plot the pivot shift before and after reconstruction. The opposite uninjured knee was used as a control. Statistical analysis was used to compare the pivot shifts before and after surgery.

RESULTS

Single-bundle ACL reconstruction produced a significant reduction in anterior translation, from a mean ± SD of 17.4 ± 3.80 mm to 6.4 ± 1.95 mm (P < .001), as well as in internal rotation, from 22.9° ± 5.91° to 7.5° ± 2.96° (P < .001). The anterior translation in the reconstructed knees was similar to the control knees, 6.4 ± 1.95 mm versus 5.6 ± 1.23 mm (P < .148), while the internal rotation was significantly less in the reconstructed knees, 7.5° ± 2.96° versus 11.9° ± 3.36° (P < .05). The values for the coupled movements were used to calculate the length of the radius of curvature, about which the tibia rotates relative to the femur, during the pivot shift. In the control knees, the mean value was 28.9 ± 8.21 mm, while there was extreme variability in the operated knee both before and after surgery.

CONCLUSION

It is possible to reduce both anterior translation and internal rotation, which occur during the pivot-shift test in the ACL-deficient knee, using single-bundle ACL reconstruction, when measured at the time of surgery. However, normal motion is not fully restored.

Radiographic landmarks for locating the femoral origin and tibial insertion of the knee anterolateral ligament

BACKGROUND

Recent anatomic studies have confirmed the presence of a true ligament structure, the anterolateral ligament (ALL), in the anterolateral region of the knee. This structure is involved in the rotatory instability of the knee and might explain why some isolated reconstructions of the anterior cruciate ligament result in a residual pivot shift. Therefore, when considering the least invasive method for reconstruction of this structure, it is important to identify the corresponding bony landmarks on radiographic images.

PURPOSE

To establish radiographic femoral and tibial landmarks for the ALL in frontal and lateral views.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten unpaired cadaver knees were dissected. The attachments of the ALL were isolated and its anatomic parameters were quantified. Its origin and insertion were marked with a 2-mm-diameter metallic sphere, and radiographs were taken from frontal and lateral views. The obtained images were analyzed and the ALL parameters established.

RESULTS

The origin of the ALL in the lateral view was found at a point an average ± SD of 47.5% ± 4.3% from the anterior edge of the femoral condyle and about 3.7 ± 1.1 mm below the Blumensaat line. In the frontal view, the origin was about 15.8 ± 1.9 mm from the distal condyle line. The ALL insertion was an average of 53.2% ± 5.8% from the anterior edge of the lateral tibial plateau in the lateral view and 7.0 ± 0.5 mm below the lateral tibial plateau in the frontal view. In anatomic dissections, the origin of the ALL was 1.9 ± 1.4 mm anterior and 4.1 ± 1.1 mm distal to the lateral collateral ligament, and the insertion was 4.4 ± 0.8 mm below the lateral tibial plateau cartilage.

CONCLUSION

The ALL origin on an absolute lateral radiograph of the knee is approximately 47% of the anterior-posterior size of the condyle and 3.7 mm caudal to the Blumensaat line. In a frontal radiograph, the ALL is 15.8 mm from the posterior bicondyle line. The ALL insertion is approximately 53.2% of the anterior-posterior size of the plateau in the lateral view and 7.0 mm below the articular line in the frontal view.

CLINICAL RELEVANCE

Knowledge of the anatomic landmarks of the ALL on radiography will permit minimally invasive surgical reconstruction with lower morbidity.

MRI evaluation of the anterolateral ligament of the knee: assessment in routine 1.5-T scans

OBJECTIVE

This study evaluated the ability of routine 1.5-T MRI scans to visualize the anterolateral ligament (ALL) and describe its path and anatomic relations with lateral knee structures.

MATERIALS AND METHODS

Thirty-nine 1.5-T MRI scans of the knee were evaluated. The scans included an MRI knee protocol with T1-weighted sequences, T2-weighted sequences with fat saturation, and proton density (PD)-weighted fast spin-echo sequences. Two radiologists separately reviewed all MRI scans to evaluate interobserver reliability. The ALL was divided into three portions for analyses: femoral, meniscal, and tibial. The path of the ALL was evaluated with regard to known structural parameters previously studied in this region.

RESULTS

At least a portion of the ALL was visualized in 38 (97.8%) cases. The meniscal portion was most visualized (94.8%), followed by the femoral (89.7%) and the tibial (79.4%) portions. The three portions of the ALL were visualized in 28 (71.7%) patients. The ALL was characterized with greater clarity on the coronal plane and was visualized as a thin, linear structure. The T1-weighted sequences showed a statistically inferior ligament visibility frequency. With regard to the T2 and PD evaluations, although the visualization frequency in PD was higher for the three portions of the ligament, only the femoral portion showed significant values.

CONCLUSION

The ALL can be visualized in routine 1.5-T MRI scans. Although some of the ligament could be depicted in nearly all of the scans (97.4%), it could only be observed in its entirety in about 71.7% of the tests.

Extra-articular ACL Reconstruction and Pivot Shift: In Vivo Dynamic Evaluation With Navigation

BACKGROUND

The pivot-shift test is considered a reliable examination to evaluate the results of anterior cruciate ligament (ACL) reconstruction, as it strongly correlates with patient satisfaction, giving-way episodes, and activity level. The addition of lateral tenodesis (LT) to current techniques of intra-articular reconstruction with a hamstring graft could potentially improve knee laxity in cases of severe rotational instability.

PURPOSE

To biomechanically investigate the effect of intra- and extra-articular ACL reconstructions on knee laxity and the pivot-shift phenomenon.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty patients underwent anatomic single-bundle ACL reconstruction with doubled semitendinosus and gracilis tendons with the addition of extra-articular reconstruction. In patients in group A, intra-articular reconstruction was performed first and LT thereafter; in patients in group B, LT was performed first and intra-articular reconstruction thereafter. A navigator equipped with software designed for both static and dynamic evaluations was used to measure maximum anterior tibial translation (ATT) and axial tibial rotation (ATR) at 30° of flexion (static evaluation) and during the pivot-shift test (dynamic evaluation). Measurements were performed before reconstruction, after the first procedure, and after the second procedure.

RESULTS

For the static evaluation, in group A, the mean ATT significantly decreased from 14.1 ± 3.7 mm in the preoperative (ACL-deficient) condition to 6.0 ± 1.9 mm after ACL reconstruction and to 5.3 ± 1.6 mm after LT. The mean ATR at 30° of knee flexion significantly decreased from 35.7° ± 4.8° to 28.9° ± 4.1° and to 20.9° ± 4.8°, respectively. In group B, the mean ATT significantly decreased from 13.5 ± 6.5 mm in the preoperative (ACL-deficient) condition to 10.2 ± 3.2 mm after LT and to 4.0 ± 1.6 mm after ACL reconstruction. The mean ATR at 30° of knee flexion significantly decreased from 36.7° ± 4.8° to 26.2° ± 6.2° and to 23.5° ± 4.9°, respectively. For the dynamic evaluation (pivot-shift test), in group A, the mean ATT significantly decreased from 15.0 ± 6.8 mm in the preoperative (ACL-deficient) condition to 9.4 ± 6.4 mm after ACL reconstruction and to 8.5 ± 5.4 mm after LT. The mean ATR significantly decreased from 16.9° ± 4.7° to 11.6° ± 4.1° and to 6.1° ± 2.2°, respectively. In group B, the mean ATT significantly decreased from 12.5 ± 3.3 mm in the preoperative (ACL-deficient) condition to 9.1 ± 5.9 mm after LT and to 8.1 ± 5.4 mm after ACL reconstruction. The mean ATR significantly decreased from 16.0° ± 4.5° to 9.2° ± 4.3° and to 7.5° ± 4.0°, respectively.

CONCLUSION/CLINICAL RELEVANCE

Extra-articular reconstruction had little effect in reducing the anterior displacement of the tibia at 30° of flexion, but it was more effective than intra-articular reconstruction in reducing ATR. Anatomic ACL reconstruction and LT were synergic in controlling the pivot-shift phenomenon.

Human knee laxity in ACL-deficient and physiological contralateral joints: intra-operative measurements using a navigation system

Background

The comprehension of human knee laxity and of the failures of relevant surgical reconstructions of the anterior cruciate ligament (ACL) can be enhanced by the knowledge of the laximetric status of the contralateral healthy knee (CHK). Rarely this is available in patients, directly from the skeletal structures, and for a number of the standard clinical tests. The general aim of this study was to measure the extent to which laxity occurs immediately before surgery in the ACL deficient knee (ADK) with respect to CHK, in a number of standard clinical evaluation tests.

Method

Thirty-two patients with ACL deficiency were analyzed at ADK and at CHK by a navigation system immediately before reconstructions. Knee laxity was assessed based on digitized anatomical references during the antero-posterior drawer, Lachman, internal-external rotation, varus-valgus, and pivot-shift tests. Antero-posterior laxity was normalized based on patient-specific length of the tibial plateau.

Results

In the drawer test, statistical significance (p < 0.05) was found for the larger antero-posterior laxity in ADK than in CHK, on average, of 54' in the medial and 47' in the lateral compartments, when measured in normalized translations. In the Lachman test, these were about 106' and 68'. The pivot-shift test revealed a significant 70' larger antero-posterior central laxity and a 32' larger rotational laxity. No statistically relevant differences were observed in the other tests.

Conclusion

The first conclusion is that it is important to measure also the antero-posterior and rotational laxity of the uninjured contralateral knee in assessing the laxity of the injured knee. A second is that the Lachman test shows knee laxity better than the AP drawer, and that the pivot-shift test was the only one able to reveal rotational instability. The present original measurements and analyses contribute to the knowledge of knee joint mechanics, with possible relevant applications in biomedical and clinical research.

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament

PURPOSE

The purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics.

METHODS

Three different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation.

RESULTS

The ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role.

CONCLUSION

From this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics.

Anatomy and Histology of the Knee Anterolateral Ligament

BACKGROUND

Reconstruction of the anterior cruciate ligament (ACL) is one of the most common procedures in orthopaedic surgery. However, even with advances in surgical techniques and implants, some patients still have residual anterolateral rotatory laxity after reconstruction. A thorough study of the anatomy of the anterolateral region of the knee is needed.

PURPOSE

To study the anterolateral region and determine the measurements and points of attachments of the anterolateral ligament (ALL).

STUDY DESIGN

Descriptive laboratory study.

METHODS

Dissections of the anterolateral structures of the knee were performed in 20 human cadavers. After isolating the ALL, its length, thickness, width, and points of attachments were determined. The femoral attachment of the ALL was based on the anterior-posterior and proximal-distal distances from the attachment of the lateral collateral ligament (LCL). The tibial attachment point was based on the distance from the Gerdy tubercle to the fibular head and the distance from the lateral tibial plateau. The ligaments from the first 10 dissections were sent for histological analysis.

RESULTS

The ALL was found in all 20 knees. The femoral attachment of the ALL at the lateral epicondyle averaged 3.5 mm distal and 2.2 mm anterior to the attachment of the LCL. Two distal attachments were observed: one inserts into the lateral meniscus, the other between the Gerdy tubercle and the fibular head, approximately 4.4 mm distal to the tibial articular cartilage. The mean measurements for the ligament were 37.3 mm (length), 7.4 mm (width), and 2.7 mm (thickness). The histological analysis of the ligaments revealed dense connective tissue.

CONCLUSION

The ALL is consistently present in the anterolateral region of the knee. Its attachment to the femur is anterior and distal to the attachment of the LCL. Moving distally, it bifurcates at close to half of its length. The ALL features 2 distal attachments, one at the lateral meniscus and the other between the Gerdy tubercle and the fibular head.

CLINICAL RELEVANCE

The ALL may be important in maintaining normal rotatory limits of knee motion; ALL rupture could be responsible for rotatory laxity after isolated intra-articular reconstruction of the ACL.

Anatomical study on the anterolateral ligament of the knee

Objective

Describe the knee anterolateral ligament (ALL) and establish its anatomical marks of origin and insertion.

Methods

Dissection of the anterolateral aspect of the knee was performed in six cadavers. After isolation of the ALL, its lenght, width and thickness were measured as its places of origin and insertion. The ALL origin was documented in relation to the lateral collateral ligament (LCL) origin and the insertion was documented in relation to the Gerdy tubercle, fibullar head and lateral meniscus. After the first two dissections, the ligament was removed and sent to histologycal analysis.

Results

The ALL was clearly identified in all knees. Its origin in the lateral epycondile was on average 0.5 mm distal and 2.5 mm anterior to the LCL. In the tibia, two insertions were observed, one in the lateral meniscus and another in the proximal tibia, about 4.5 mm distal to the articular cartilage, between the Gerdy tubercle and the fibullar head. The average measures obtained were: 35.1 mm lenght, 6.8 mm width and 2.6 mm thickness. In the ligament histological analysis, dense connective tissue was observed.

Conclusion

The ALL is a constant structure in the knee anterolateral region. Its origin is anterior and distal to the LCL origin. In the tibia, it has two insertions, one in the lateral meniscus and another in the proximal tibia between the Gerdy tubercle and the fibullar head.

Effect of partial medial meniscectomy on anterior tibial translation in stable knees: a prospective controlled study on 32 patients

BACKGROUND

Quantitative measurement of anterior translation of the tibia (ATT) by KT 1000 is used mainly to provide an objective assessment of knee laxity after anterior cruciate ligament (ACL) tears or ACL reconstructions. Only few papers described its use after menisectomies in knees with intact ACL. The objective of this paper is to determine whether partial medial meniscectomies could induce significant immediate post-operative ATT.

METHODS

Thirty-two patients with a diagnosis of partial medial meniscal tear limited to the posterior horn and documented with magnetic resonance imaging (MRI) were assessed under anesthesia before and immediately after arthroscopic meniscectomy. The assessment was performed by the same examiner by means of the MEDmetric(R) KT-1000 instrument using manual maximum (MM) force. The opposite knees were also assessed.

RESULTS

There is a significant difference between pre and post-operative KT MM mean values for the operated knees (CI: -3.933953 to -2.947297, p < 0.0001). No significance was found between the mean values for the contralateral knees before and after the completion of the menisectomy on the operated knees (p = 0.4). For the operated knees, 14 (43.75%) had a side-to-side difference between pre-and post-operative values of more than 3 mm, whereas for the contralateral knees, only 2 (6%) had the same.

CONCLUSION

Less than half of operated knees showed significant side-to-side difference values of ATT (>3 mm), immediately after meniscectomies in unconscious patients. Our values might reflect a temporarily increase of anterior laxity under specific conditions but whether a significant laxity remains in some knees, such changes may lead to higher cartilage loading and early osteoarthritis.

Rotatory instability of the knee after ACL tear and reconstruction

Although ACL reconstructions provide satisfactory clinical results nowadays, regardless of the type of graft or the surgical technique used (out-in vs in-out or single- vs double-bundle), the residual rotatory instability which is often detected at clinical follow-ups is still a matter of concern among surgeons. In this paper we try to analyze all the aspects which might contribute to this phenomenon by summarizing the biomechanical functions of the two bundles of the ACL, and by evaluating all the other factors strictly related to the rotatory instability of a reconstructed knee, such as the anatomical positioning of the single- or double-bundle new ACL, or the importance of a valid lateral compartment (LCL, ALTFL). Clinical, biomechanical and cadaver studies are discussed in order to contribute to better understanding of the origin of post-operative residual rotatory instability.

Do pre-operative knee laxity values influence post-operative ones after anterior cruciate ligament reconstruction?

The objective of this study was to verify whether pre-reconstruction laxity condition effects post-reconstruction outcome. A total of 100 patients who underwent navigated Anterior Cruciate Ligament (ACL) reconstruction were included in the study and knee laxity analysed retrospectively. The knee was assessed in six different laxity tests before and after ACL reconstruction, namely antero-posterior (AP) and internal-external (IE) at 30° and 90°, and varus-valgus (VV) rotations at 0° and 30° of flexion. For each test, the least square (LS) fitting line based on pre-operative-to-post-operative laxity value was calculated. To what degree the post-operative laxity value is explainable by the corresponding pre-operative condition was evaluated by the LS line slope. Post-operatively, for each single patient, the grade of laxity decreased at any evaluated test. The strongest influence of pre-operative-to-post-operative laxity values was found during IE30 and IE90 tests. While AP30 and VV0 tests seem to be those in which the post-reconstruction laxity was barely affected by the pre-surgery condition. The analysis of the global laxity reduction confirms the previous results. Following this hypothesis, our study remarks on the importance of combined lesions to secondary restraints and the importance of fully understanding the residual laxity to optimize the surgical technique.

Does the posterolateral bundle influence rotational movement more than the anteromedial bundle in anterior cruciate ligament reconstruction?

The biomechanical function of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) remains controversial. Some studies report that the AM bundle stabilises the knee joint in anteroposterior (AP) translation and rotational movement (both internal and external) to the same extent as the PL bundle. Others conclude that the PL bundle is more important than the AM in controlling rotational movement.

The objective of this randomised cohort study involving 60 patients (39 men and 21 women) with a mean age of 32.9 years (18 to 53) was to evaluate the function of the AM and the PL bundles of the ACL in both AP and rotational movements of the knee joint after single-bundle and double-bundle ACL reconstruction using a computer navigation system. In the double-bundle group the patients were also randomised to have the AM or the PL bundle tensioned first, with knee laxity measured after each stage of reconstruction. All patients had isolated complete ACL tears, and the presence of a meniscal injury was the only supplementary pathology permitted for inclusion in the trial. The KT-1000 arthrometer was used to apply a constant load to evaluate the AP translation and the rolimeter was used to apply a constant rotational force. For the single-bundle group deviation was measured before and after ACL reconstruction. In the double-bundle group deviation was measured for the ACL-deficient, AM- or PL-reconstructed first conditions and for the total reconstruction.

We found that the AM bundle in the double-bundle group controlled rotation as much as the single-bundle technique, and to a greater extent than the PL bundle in the double-bundle technique. The double-bundle technique increases AP translation and rotational stability in internal rotation more than the single-bundle technique.

Dynamic knee laxity measurement devices

PURPOSE

Studies have reported that knee kinematics and rotational laxity are not restored to native levels following traditional anterior cruciate ligament (ACL) reconstruction. This has led to the development of anatomic ACL reconstruction, which aims to restore native knee kinematics and long-term knee health by replicating normal anatomy as much as possible. The purpose of this review is to give an overview of current dynamic knee laxity measurement devices with the purpose of investigating the significance of dynamic laxity measurement of the knee. Gait analysis is not included.

METHODS

The subject was discussed with experts in the field in order to perform a level V review. MEDLINE was searched according to the discussions for relevant articles using multiple different search terms. All found abstracts were read and scanned for relevance to the subject. The reference lists of the relevant articles were searched for additional articles related to the subject.

RESULTS

There are a variety of techniques reported to measure dynamic laxity of the knee. Technical development of methods is one important part toward better understanding of knee kinematics. Validation of devices has shown to be difficult due to the lack of gold standard. Different studies use various methods to examine different components of dynamic laxity, which makes comparisons between studies challenging.

CONCLUSION

Several devices can be used to evaluate dynamic laxity of the knee. At the present time, the devices are continuously under development. Future implementation should include primary basic research, including validation and reliability testing, as well as part of individualized surgery and clinical follow-up.

LEVEL OF EVIDENCE

Diagnostic study, Level V.

What does it take to have a high-grade pivot shift?

The pivot shift is the most specific clinical test to assess pathological knee joint rotatory laxity following ACL injury. This article attempts to describe the anatomic structures responsible for creating a high-grade pivot shift and their potential role in customizing ACL reconstruction. A review of the literature demonstrates that disruption of the secondary stabilizers of anterior translation of the lateral compartment including the lateral meniscus, anterolateral capsule, and IT band contributes to a high-grade pivot shift in the ACL-deficient knee. The morphology of the lateral tibial plateau, including increased posteroinferior tibial slope and small size, can also contribute to high-grade pivot shift. Factors that may decrease the grade of the pivot shift include medial compartment injury, MCL injury, patient guarding, and osteoarthritis. In conclusion, a high-grade pivot shift in the ACL-deficient knee is often associated with incompetence of the lateral soft tissue envelope. Rotatory laxity as assessed by the pivot shift may also be falsely underestimated by concomitant injuries.

LEVEL OF EVIDENCE

IV.