Knee laxity modifications after ACL rupture and surgical intra- and extra-articular reconstructions: intra-operative measures in reconstructed and healthy knees

Utility of three-dimensional proton density-weighted sequence MRI in knee for the assessment of Anterolateral complex in Anterior cruciate ligament injury

OBJECTIVES

To assess the proportion and pattern of injury of the anterolateral ligament (ALL) and the Kaplan fibre (KF) complex in knees with anterior cruciate ligament (ACL) injuries on MRI using three-dimensional (3D) proton density (PD) sequences.

METHODS

A total of 88 patients having ACL injury were included in this cross-sectional study. 3D PD sequences were used to assess injury of ALL and the KF complex and were graded on a scale of 0 to 3. MR images were evaluated by two radiologists. Interobserver agreement was determined using Cohen Kappa.

RESULTS

Femoral, meniscal, and tibial portions of ALL were visualized in 90.9%, 92%, and 94.3% of the study subjects, respectively. Proximal and distal KF were visualized in 92% and 93.2% of patients, respectively. Injury to ALL and KF was seen in 63.6% and 17% of the patients, respectively. Excellent interobserver agreement was noted for the identification and grading of ALL and KF complex injuries.

CONCLUSIONS

Oblique reformatted 3DPD MRI reliably detect ALC; however, ALL injury is better characterized than KF injury using this sequence.

ADVANCES IN KNOWLEDGE

Given the potential role of anterolateral complex (ALC) in maintaining the rotational stability of the knee, ALC assessment using the 3D PD sequences and their oblique reformatted images should be incorporated as routine review area of the knee MRI, particularly in the setting of ACL tear.

Knee Flexion Angle of Fixation During Anterolateral Ligament Reconstruction or Lateral Extra-articular Tenodesis: A Systematic Review and Meta-analysis of Lateral Extra-articular Reinforcement Techniques Performed in Conjunction With ACL Reconstruction

Background

Anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET) is being used more frequently in conjunction with anterior cruciate ligament reconstruction (ACLR). However, the knee flexion angle at which fixation of ALLR or LET is performed during the procedure is quite variable based on existing technique descriptions.

Purpose/Hypothesis

The purpose of this study was to identify whether flexion angle at the time of ALLR/LET fixation affected postoperative outcomes in a clinical population. It was hypothesized that ALLR/LET fixation at low versus high flexion angles would lead to no statistically significant differences in patient-reported outcome measures and graft failure rates.

Study Design

Systematic review; Level of evidence, 4.

Methods

The PubMed, Embase, and Cochrane Library databases were searched according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify published clinical studies of ACLR with ALLR/LET in which the knee flexion angle at the time of ALLR/LET was reported. A priori, low flexion was defined as 0° to 30°, and high flexion was defined as 60° to 90°. Studies were excluded if the flexion angle was between 31° and 59° because these angles constituted neither low nor high flexion angles and including them in an analysis of high versus low flexion angle at fixation would have biased the study results toward the null. The overall risk of bias was assessed using the Newcastle-Ottawa Scale. The pooled results of the studies were analyzed using the International Knee Documentation Committee (IKDC), Lysholm, and Tegner scores, along with reported graft failure rates.

Results

A total of 32 clinical studies (5230 patients) met inclusion criteria: 22 studies (1999 patients) in the low-flexion group and 10 studies (3231 patients) in the high-flexion group. The median Newcastle-Ottawa Scale score was 6. Comparisons of patients with a low flexion angle versus a high flexion angle demonstrated no differences in the IKDC (P = .84), Lysholm (P = .67), or Tegner (P = .44) scores or in graft failure (3.4% vs 4.1%, respectively; P = .69).

Conclusion

The results of this review indicated that ACLR performed in conjunction with ALLR/LET provides good to excellent patient-reported outcomes and low graft failure rates when ALLR/LET fixation is performed in either low or high knee flexion.

Arthroscopic Anatomic Anterior Cruciate Ligament Primary Repair Restores Anterior Tibial Translation Intraoperatively at Time Zero With No Additional Effect of Suture Augmentation

PURPOSE

To intraoperatively evaluate the ability of anterior cruciate ligament (ACL) primary repair (ACLPR) to restore anterior tibial translation (ATT) at time zero and to assess the influence of additional suture augmentation (SA) on ATT.

METHODS

Patients with proximal ACL tears undergoing arthroscopic ACLPR with dual-suture anchor fixation were included in this time-zero clinical study. Laxity measurements were taken with a digital arthrometer to evaluate ATT stability preoperatively in the office (T0) as a standardized diagnostic tool, preoperatively under anesthesia (T1), at time zero intraoperatively after ACLPR but prior to SA fixation (T2), and after SA fixation (T3).

RESULTS

A total of 27 patients (mean age ± standard deviation [SD], 35.1 ± 12.0 years) with proximal ACL tears and significant preoperative (T0) ATT side-to-side differences (SSDs) (mean ± SD, 4.1 ± 1.5 mm) were evaluated. ACLPR was shown to restore ATT SSD at time zero (mean ± SD, 0.2 ± 1.1 mm) given that a significant reduction in ATT SSD (mean difference ± standard error, -4.7 ± 0.21 mm; P < .001) was achieved when comparing preoperative and intraoperative measurements after separate refixation of both ACL bundles with suture anchors. Additional SA fixation did not further decrease ATT when comparing measurements of the ipsilateral leg after ACL refixation and after SA fixation (mean difference ± SD, 0.03 ± 0.22 mm; P = .496).

CONCLUSIONS

ACLPR with dual-suture anchor fixation restores time-zero ATT laxity in adults with proximal ACL tears. Additional SA fixation in full knee extension does not further decrease ATT.

CLINICAL RELEVANCE

This study provides important information about the effectiveness of ACLPR in restoring ATT. SA with the knee fixed in full knee extension does not further decrease ATT; therefore, augmentation may not lead to overconstraint of the knee or stress shielding of the repaired ACL.

Determining the relationship between tibiofemoral geometry and passive motion with partial least squares regression

Tibiofemoral geometry influences knee passive motion and understanding their relationship can provide insight into knee function and mechanisms of injury. However, the complexity of the geometric constraints has made characterizing the relationship challenging. The aim of this study was to determine the tibiofemoral bone geometries that explain the variation in passive motion using a partial least squares regression (PLSR) model. The PLSR model was developed for 29 healthy cadaver specimens (10 female, 19 male) with femur and tibia geometries retrieved from MRI images and six degree-of-freedom tibiofemoral kinematics determined during a flexion cycle with minimal medial pressure. The first 13 partial least squares (PLS) components explained 90% of the variation in the kinematics and accounted for 89% of the variation in geometry. The first three PLS components which shared geometric changes to particular surface congruencies of the tibial and femoral condyles explained the most amount of variation in the kinematics, primarily in anterior-posterior translation. Meanwhile, variations in femoral condyle width and the intercondylar space, tibia plateau size and conformity, and tibia eminences heights in PLS 2 and 4 explained the greatest amount of variation in internal-external rotation. PLS 4 exhibiting variation in overall size of the knee accounted for greatest amount of variation in geometry (50%) and had the greatest influence on the abduction-adduction motion and some on internal-external rotation but, overall, explained only a small proportion of the kinematics (10%). Elucidating the complex relationship between tibiofemoral bone geometry and passive kinematics may help personalize treatments for improved functional outcomes in patients.

Navigation in anterior cruciate ligament reconstruction: State of the art

Computer navigation (CN) for anterior cruciate ligament (ACL) surgery has been used mainly for two purposes: to enhance the accuracy of tunnel position and to evaluate the kinematics of the ACL reconstruction (ACLR) and the stability achieved by different surgical techniques. Many studies have shown that navigation may improve the accuracy of anatomical tunnel orientation and position during ACL reconstructive surgery compared with normal arthroscopic tunnel placement, especially regarding the femoral side. At the same time, it has become the gold-standard method for intraoperative knee kinematic assessment, as it permits a quantitative multidirectional knee joint laxity evaluation. CN in ACL surgery has been associated with diverse problems. First, in most optic systems additional skin incisions and drill holes in the femoral bone are required for fixation of a reference frame to the femur. Second, additional radiation exposure and extra medical cost to the patient for preoperative planning are usually needed. Third, CN, due to additional steps, has more opportunities for error during preoperative planning, intraoperative registration, and operation. Fourth, soft tissues, including the skin and subcutaneous tissues, are usually not considered during the preoperative planning, which can be a problem for kinematic and stability assessment. Many studies have concluded that ACLR using a CN system is more expensive than conventional surgery, it adds extra time to the surgery and it is not mitigated by better clinical outcomes. This, combined with costs and invasiveness, has limited the use of CN to research-related cases. Future technology should prioritize less invasive intra-operative surgical navigation.

Surgical intra- and extra-articular anterior cruciate ligament reconstruction: a meta-analysis

BACKGROUND

It is still controversial whether the combination of anterior cruciate ligament (ACL) reconstruction and extra-articular reconstruction (EAR) have good clinical efficacy. This meta-analysis aims systematically to compare the clinical effectiveness of ACL reconstruction and combined reconstruction.

METHODS

Electronic databases, including Medline/PubMed, Embase and the Cochrane Library, were systematically searched to identify targeted studies. A meta-analysis were performed to pool the outcome estimates of interest, such as the Lysholm, International Knee Documentation Committee (IKDC) and Tegner scores and the results from the KT-1000/2000 arthrometer test, the Lachman test and the pivot shift test.

RESULTS

Twelve studies involving 1146 knees were identified. Compared with single ACL reconstruction, combined reconstruction had better results for a pivot shift of grade 1 (relative ratio [RR] = 0.88, 95% CI: 0.83-0.94) and grade 2 (RR = 0.95, 95% CI: 0.91-0.99) rather than grade 3 (RR = 0.98, 95% CI: 0.90-1.06) and no statistically significant difference for both Lachman grade 1 (RR = 0.96, 95% CI: 0.89-1.05) and grade 2 (RR = 0.96, 95% CI: 0.90-1.03). Combined reconstruction resulted in significant improvements on the instrumented joint laxity test when considering a failure standard of more than 5 mm (a side-to-side arthrometric difference) (RR = 0.94, 95% CI: 0.89-0.98) rather than 3 mm (RR = 0.94, 95% CI: 0.86-1.03). Moreover, combined reconstruction increased the IKDC score at the 12-month (weighted mean difference [WMD] = - 6.38, 95% CI: - 9.66 to - 3.10), 24-month (WMD = - 5.60, 95% CI: - 8.54 to - 2.66) and 36-month follow-ups (WMD = - 4.71, 95% CI: - 7.59 to - 1.83) and the Tegner score at the 36-month follow-up (WMD = - 0.53, 95% CI: - 0.97 to - 0.09), but it did not increase the Lysholm score at the 36-month follow-up (WMD = - 0.84, 95% CI: - 2.02 to 0.34).

CONCLUSION

With the advances in reconstruction techniques, combined reconstructions were found to be effective in improving rotational stability and to lead to good functional scores. However, obviously, the combined reconstruction technique is more time-consuming and requires an additional incision, which is not suitable for all ACL-deficient patients. Therefore, programs should be personalized and customized for the specific situation of each patient.

ACL Reconstruction with Augmentation: a Scoping Review

PURPOSE OF REVIEW

We reviewed the recent literature to identify and summarize new research surrounding anterior cruciate ligament reconstruction (ACLR) with augmentation in the form of additional soft tissue procedures or biologic augmentation. Specifically, we wanted to review the failure rates of these procedures in both the primary and revision settings.

METHODS

The databases Embase, PubMed, and Medline were searched on August 13, 2018, for English-language studies that reported on the use of anterior cruciate ligament reconstruction (primary and revision) in conjunction with either soft tissue or biologic augmentation. The studies were systematically screened and data abstracted in duplicates.

RECENT FINDINGS

Advancements in ACLR surgery, including soft tissue augmentation, may decrease primary and revision surgery failure rates for high-risk patients. The use of biological augmentation has shown histologic and radiographic improvements. These differences, however, have failed to be statistically significant and have not resulted in clinically significant improvements in outcome. The limited body of evidence has shown that the addition of soft tissue procedures may in fact lower the risk of graft re-rupture rates particularly in revision or in patients wishing to return to high-risk sports and activities. The use of biologic augmentation although promising in laboratory studies has yet to show any significant clinical results and therefore will require further studies to prove any efficacy.

Percutaneous Medial Ligament Reconstruction for Valgus and Rotational Knee Instability

The following surgical technique is intended for patients with chronic valgus laxity and rotational knee instability. It is a percutaneous 2-bundle ligament reconstruction method that uses the semitendinosus tendon, allowing it to remain pedicled to its distal tibial insertion. The aim is to correct the laxity without otherwise limiting the motion of the knee.

Two Different Knee Rotational Instabilities Occur With Anterior Cruciate Ligament and Anterolateral Ligament Injuries: A Robotic Study on Anterior Cruciate Ligament and Extra-articular Reconstructions in Restoring Rotational Stability

PURPOSE

To determine the effect of 2 extra-articular reconstructions on pivot-shift rotational stability and tibial internal rotation as a basis for clinical recommendations.

METHODS

A robotic simulator tested 15 cadaver knees. Group 1 (anterior cruciate ligament [ACL] cut) underwent ACL bone-patellar tendon-bone reconstruction followed by sectioning the anterolateral structures and an extra-articular, manual-tension iliotibial band (ITB) tenodesis. Group 2 (ACL intact) tested the rotational stabilizing effect of a low-tension ITB tenodesis before and after sectioning the anterolateral ligament/ITB structures. Lateral and medial tibiofemoral compartment translations and internal-external tibial rotations were measured under Lachman, 5N·m tibial rotation, and 2 pivot-shift simulations using 4-degree-of-freedom loading. Statistical equivalence was defined within 2 mm tibiofemoral compartment translation and 2° tibial rotation at P < .05.

RESULTS

The bone-patellar tendon-bone ACL reconstruction (group 1) restored pivot-shift lateral compartment translation within 0.7 mm (95% confidence interval [CI], -0.6 to 1.9; P = .70) of normal. The internal rotation limit was not affected by ACL sectioning or reconstruction. After anterolateral ligament/ITB sectioning there was no change in pivot-shift lateral compartment translation, however internal rotation increased 2.9° (95% CI, 0.6-5.2; P = .99) at 90° flexion. The manual-tension ITB tenodesis (fixated 13-22 N tension) decreased pivot-shift lateral compartment translation 4.8 mm (95% CI, 1.4-8.1; P = .99) and internal rotation by 21.9° (95% CI, 13.2-30.6; P = .99) at 90° flexion. The ACL forces decreased 45.8% in the pivot-shift test. In group 2 knees, with the ACL intact, the anterolateral ligament/ITB sectioning had no effect on pivot-shift translations; however, the internal rotation limit increased by 4.3° (95% CI, 1.9-6.8; P = .99) at 60° flexion. The low-tension ITB tenodesis (fixated 8.9 N tension) had no effect on pivot-shift translations and corrected internal tibial rotation with a mild overconstraint of 4.2° (95% CI, 1.9-6.8; P = .99) at 60° flexion.

CONCLUSIONS

A low-tension ITB tenodesis, fixated at neutral tibial rotation to avoid constraining internal tibial rotation, has no effect in limiting abnormal pivot-shift subluxations.

CLINICAL RELEVANCE

A low-tension ITB tenodesis has limited clinical utilization as the pivot-shift subluxations are not affected, assuming appropriate tensioning to not overconstrain internal tibial rotation.

Percutaneous Medial Ligament Reconstruction for Valgus Knee Instability

Injuries to stabilizing elements on the medial side of the knee are one of the most common knee ailments. Because of the good healing capacity of these structures, acute injuries are typically treated conservatively. However, valgus laxity near full extension can persist in some patients. This laxity may be the source of instability due to medial joint space opening, which then requires surgical treatment. Various procedures have been described that aim to reproduce the anatomy of the medial collateral ligament (MCL) and the posterior oblique ligament (POL), which work together to stabilize the medial aspect of the knee. However, these are complex open surgical procedures, technically demanding to achieve the favorable isometry, which prevent joint contracture or recurrence of laxity. The purpose of this study was to describe a short construct that minimizes the risk of secondary loss of tension and complies with the principle of favorable anisometry. The graft is positioned in the joint opening axis, between the deep bundle of the MCL and the POL.

The Augmentation of Revision Anterior Cruciate Ligament Reconstruction With Modified Iliotibial Band Tenodesis to Correct the Pivot Shift: A Computer Navigation Study

BACKGROUND

Iliotibial band (ITB) tenodesis improves stability and functional outcomes when added to anterior cruciate ligament (ACL) reconstruction. Its precise indications are unknown. Persistence of the pivot shift after revision ACL reconstruction may be one indication.

HYPOTHESIS

The addition of ITB tenodesis for a persistent pivot shift after revision ACL reconstruction will improve stability and activity levels.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Adults with recurrent ACL ruptures underwent revision ACL reconstruction, followed by a pivot-shift test before the surgery ended. If the pivot shift was grade 0 or 1, no further surgery was performed (group 1). If it was grade 2 or 3, ITB tenodesis was performed (group 2). The pivot-shift test was performed, graded, and measured using computer navigation before revision ACL reconstruction and after revision ACL reconstruction with and without ITB tenodesis. Tegner activity scores were obtained 2 years after surgery. Groups were compared with regard to anterior translation and internal rotation during the pivot shift as well as Tegner activity scores ( P < .05).

RESULTS

There were 20 patients in group 1 and 18 in group 2. The mean anterior translation improved in group 1, from 17.7 ± 3.5 mm to 6.6 ± 1.9 mm, and group 2, from 18.5 ± 3.3 mm to 6.1 ± 1.2 mm, after revision ACL reconstruction ( P < .001), with no difference between the groups ( P = .15). After ITB tenodesis, the reduction in anterior translation in group 2 (5.3 ± 1.5 mm) became greater than that in group 1 (6.6 ± 1.9 mm) ( P = .03). In both groups after revision ACL reconstruction, there was a reduction in internal rotation (group 1: 24.2° ± 4.0° to 10.3° ± 1.1°; group 2: 25.4° ± 3.7° to 14.6° ± 2.8°; P < .001), but this change was less in group 2 ( P = .02). After ITB tenodesis, internal rotation in group 2 (8.3° ± 2.6°) became less than that in group 1 (10.3° ± 1.1°) ( P = .02). The mean Tegner activity scores in group 1 were 8.1 ± 1.1 before surgery and 7.4 ± 0.9 after surgery, while in group 2 they were 7.0 ± 1.3 and 7.2 ± 0.4, respectively, and not significantly different ( P = .29).

CONCLUSION

ITB tenodesis improved laxity, although it did not affect activity levels, when there was a persistent pivot shift after revision ACL reconstruction.

CLINICAL RELEVANCE

An indication to perform ITB tenodesis is the persistence of a grade ≥2 pivot shift after revision ACL reconstruction.

The Effects of Anterolateral Tenodesis on Tibiofemoral Contact Pressures and Kinematics

BACKGROUND

Anterolateral tenodeses are increasingly popular in combination with intra-articular anterior cruciate ligament reconstructions. Despite the perception of risk of overconstraint and lateral osteoarthritis, evidence is lacking regarding the effect of graft tensioning on knee kinematics and intra-articular compartmental joint pressures.

PURPOSE

To investigate tibiofemoral joint contact pressures and kinematics related to an anterolateral lesion and the effectiveness of a MacIntosh tenodesis in restoring these when varying (1) graft tension and (2) tibial rotation during graft fixation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric knees were tested in a customized rig with femur fixed and tibia free to move from 0° to 90° of flexion. The quadriceps and iliotibial band were loaded by means of a weighted pulley system. At 30° intervals of knee flexion, tibiofemoral contact pressures were measured with a Tekscan sensor and tibiofemoral kinematics were recorded by use of an optical tracking system. The knee was tested intact and then with an anterolateral soft tissue transection. MacIntosh tenodeses were then tested in a randomized order with 20 N or 80 N of graft tension, each with the tibia held in neutral intact alignment or free to rotate.

RESULTS

Tibial anterior translation and internal rotation were significantly increased and lateral contact pressures significantly reduced compared with the intact knee following anterolateral soft tissue cutting ( P < .05). Contact pressures were restored with fixed neutral tibial rotation combined with 20 N or 80 N of graft tension or by a free-hanging tibia with 20 N of graft tension (all P values > .5). Grafts tensioned with 80 N caused significant overconstraint both when the tibia was fixed and free hanging (all P values < .05). Increases in the lateral tibiofemoral contact pressures were also seen when the tibia was free hanging and 80 N was used for graft tension ( P < .05).

CONCLUSION

Anterolateral soft tissue injury caused reduced lateral tibiofemoral contact pressures and altered tibiofemoral kinematics; these were restored with a MacIntosh procedure performed with 20 N of graft tension. If 80 N of graft tension was used, increased lateral contact pressures and overconstraint in internal rotation were seen. With the tibia free hanging, intact contact biomechanics were restored when 20 N of graft tension was applied, but 80 N of graft tension significantly increased lateral tibiofemoral pressures and overconstrained internal rotation. The kinematic and contact pressure effects were significantly correlated: Changes in tibial rotation caused by increased graft tension correlated with elevated lateral articular contact pressure.

CLINICAL RELEVANCE

Controlling tibial position appears important when tensioning anterolateral tenodeses. However, the identified changes were subtle and may not be clinically significant in a fully loaded knee.

Varus-valgus instability in the anterior cruciate ligament-deficient knee: effect of posterior tibial load

Background

Anterior cruciate ligament (ACL) injury is often accompanied with medial collateral ligament (MCL) injury. Assessment of varus-valgus (V-V) instability in the ACL-deficient knee is crucial for the management of the concomitant ACL-collateral ligaments injury. We evaluated the V-V laxity and investigated the effect of additional posterior tibial load on the laxity in the ACL-deficient knee. Our hypothesis was that the V-V laxity in the ACL-deficient knee was greater than that in the intact knee and attenuated by additional posterior tibial load.

Methods

Eight fresh-frozen porcine knees were used, and a 6°-of-freedom (DOF) robotic system was utilized. A 5 Nm of V-V torque was applied to the intact knee, the ACL-deficient knee, and the ACL-deficient knee with 30 N of constant posterior tibial load, at 30° and 60° of flexion. Then, the 3D path in the intact knee was reproduced on the ACL-deficient knee. The total V-V angle under 5 Nm of V-V torque was assessed and compared among the three statuses. The in situ forces of the ACL under 5 Nm of varus and valgus torques, respectively, were also calculated.

Results

The total V-V angle in the ACL-deficient knee under 5 Nm of V-V torque was significantly greater than that in the intact knee, whereas the angle in the ACL-deficient knee with 30 N of posterior tibial load was significantly smaller than that in the ACL-deficient knee and approached that in the intact knee, at both 30° and 60° of flexion. The in situ force of the ACL was approximately 30 N at 30° and 16 N at 60° of flexion under 5 Nm of both varus and valgus torques.

Conclusions

The V-V laxity in the isolated ACL-deficient knee was greater than that in the intact knee. The increased laxity was attenuated and approached that in the intact knee by adding posterior tibial load. Application of posterior tibial load is necessary for accurate assessment of V-V instability in the ACL-deficient knee. Clinically, the V-V laxity in the combined ACL-MCL or ACL-LCL injured knee may be overestimated without posterior tibial load.

Is an Anterolateral Ligament Reconstruction Required in ACL-Reconstructed Knees With Associated Injury to the Anterolateral Structures? A Robotic Analysis of Rotational Knee Stability

BACKGROUND

The effect of an anterolateral ligament (ALL) reconstruction on rotational knee stability and corresponding anterior cruciate ligament (ACL) graft forces using multiple knee loading conditions including the pivot-shift phenomenon has not been determined.

PURPOSE

First, to determine the rotational stability and ACL graft forces provided by an anatomic bone-patellar tendon-bone ACL reconstruction in the ACL-deficient knee alone and with an associated ALL/iliotibial band (ITB) injury. Second, to determine the added rotational stabilizing effect and reduction in ACL graft forces provided by an ALL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

A 6 degrees of freedom robotic simulator was used to test 7 fresh-frozen cadaveric specimens during 5 testing conditions: intact, ACL-sectioned, ACL-reconstructed, ALL/ITB-sectioned, and ALL-reconstructed. Lateral and medial tibiofemoral compartment translations and internal tibial rotations were measured under Lachman test conditions, 5-N·m internal rotation, and 2 pivot-shift simulations. Statistical equivalence within 2 mm and 2° was defined as P < .05.

RESULTS

Single-graft ACL reconstruction restored central tibial translation under Lachman testing and internal rotation under 5-N·m internal rotation torque ( P < .05). A modest increase in internal rotation under 5-N·m internal rotation torque occurred after ALL/ITB sectioning of 5.1° (95% CI, 3.6° to 6.7°) and 6.7° (95% CI, 4.3° to 9.1°) at 60° and 90° of flexion, respectively ( P = .99). Lateral compartment translation increases in the pivot-shift tests were <2 mm. ALL reconstruction restored internal rotation within 0.5° (95% CI, -1.9° to 2.9°) and 0.7° (95% CI, -2.0° to 3.4°) of the ACL-reconstructed state at 60° and 90° of flexion, respectively ( P < .05). The ALL procedure reduced ACL graft forces, at most, 75 N in the pivot-shift tests and 81 N in the internal rotation tests.

CONCLUSION

Although the ALL reconstruction corrected the small abnormal changes in the internal rotation limit at high flexion angles, the procedure had no effect in limiting tibiofemoral compartment translations in the pivot-shift test and produced only modest decreases in ACL graft forces. Accordingly, the recommendation to perform an ALL reconstruction to correct pivot-shift abnormalities is questioned.

CLINICAL RELEVANCE

The small changes in rotational stability after ALL/ITB sectioning would not seem to warrant the routine addition of an ALL reconstruction in primary ACL injuries. Clinical exceptions may exist, as in grossly unstable grade 3 pivot-shift knees and revision knees. However, the concern exists of overconstraining normal tibial rotations.

Current use of navigation system in ACL surgery: a historical review

PURPOSE

The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years.

METHODS

A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery.

RESULTS

One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined.

CONLUSIONS

Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness.

LEVEL OF EVIDENCE

IV.

Isometric Characteristics of the Anterolateral Ligament of the Knee: A Cadaveric Navigation Study

PURPOSE

To measure the variations in length during flexion and internal tibial rotation of the 3 different femoral insertions of the anterolateral ligament (ALL) while maintaining a fixed tibia insertion.

METHODS

Twelve fresh-frozen cadaver knees were analyzed using a navigation system. Maximal distance variations of the 3 different anatomic femoral insertions of the ALL were measured during knee flexion and internal tibial rotation at 20° (IR20°) and 90° (IR90°). The 3 different femoral attachments were, as published, at the center of the lateral epicondyle, distal and anterior from this position, and proximal and posterior. Each of these 3 femoral insertions was coupled to the same tibial insertion at the tibial margin, halfway between the tip of the fibular head and the prominence of the Gerdy tubercle.

RESULTS

During IR20°, variation in the distance between paired points is not different between the proximal-posterior, epicondyle, and distal-anterior femoral insertions. These variations were statistically different during IR90° for the 3 different femoral locations. In increasing degrees of flexion, there was a length decrease between paired points observed with the proximal-posterior position. A length increase was observed for both the epicondyle location and the distal-anterior location.

CONCLUSIONS

The ALL did not reveal an isometric behavior at any of the femoral insertion locations but had different length change patterns during knee flexion and internal tibial rotation at 90°. The proximal and posterior to epicondyle femoral position is the only position with a favorable isometry, as shown by being tight in extension and in internal rotation at 20° and then relaxed when the knee goes to flexion at 120° and during internal rotation at 90°.

CLINICAL RELEVANCE

Clinical relevance is significant with respect to optimizing the femoral position of an ALL reconstruction.

In Vivo Length Changes of the Anterolateral Ligament and Related Extra-articular Reconstructions

BACKGROUND

Both anatomic anterolateral ligament (ALL) and nonanatomic anterolateral reconstructions are performed to improve the stability of anterior cruciate ligament (ACL)-deficient patients. However, the in vivo length change patterns and isometry of these anterolateral reconstructions are unknown.

PURPOSE

To measure the theoretical length change patterns of the ALL and various anterolateral extra-articular reconstructions in healthy and ACL-deficient knees during in vivo weightbearing flexion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten patients with an ACL injury in 1 knee and the contralateral side intact were included. By use of magnetic resonance and dual fluoroscopic imaging techniques, the changes in length of the ALL, modeled with its femoral attachment either anterior or posterior-proximal to the fibular collateral ligament (FCL) attachment, and nonanatomic extra-articular reconstructions were measured as a function of knee flexion and were compared between the intact and ACL-deficient knees.

RESULTS

The ALL, with its femoral attachment anterior to the FCL attachment, showed a consistent length increase of approximately 50% from 0° to 90° of knee flexion. The length change of the ALL was 20% ± 6% when its femoral attachment was placed posterior-proximal to the FCL. ACL deficiency did not affect ALL length. Even minor shifts in position around the rotational axis of the femur resulted in contrary ligament kinematic patterns. An extra-articular reconstruction with the femoral attachment proximal to the lateral epicondyle and the tibial attachment on the Gerdy tubercle increased 15% ± 4% in length from 0° to 60° and shortened at 90° of flexion. When the tibial fixation of the anatomic ALL with its femoral attachment posterior to the FCL was moved to the Gerdy tubercle, a 30% ± 4% length increase over 90° occurred, without the decrease in length at 90°. A significant length increase of both theoretical reconstruction grafts was seen at 0° in ACL-deficient knees.

CONCLUSION

An anatomic ALL reconstruction as modeled based on recent anatomic studies was not isometric during in vivo knee flexion and was not affected by ACL deficiency. The nonanatomic extra-articular reconstructions demonstrated more biomechanically favorable length change patterns with the smallest percentage increase in elongation during knee flexion.

CLINICAL RELEVANCE

This study presents the first in vivo biomechanical data on the ALL, in both healthy and ACL-deficient knees, and provides surgical information that may be valuable for restoring normal anterolateral stability.

Objective measures on knee instability: dynamic tests: a review of devices for assessment of dynamic knee laxity through utilization of the pivot shift test

Current reconstructive methods used after anterior cruciate ligament (ACL) injury do not entirely restore native knee kinematics. Evaluation of dynamic knee laxity is important to accurately diagnose ACL deficiency, to evaluate reconstructive techniques, and to construct treatment algorithms for patients with ACL injury. The purpose of this study is to present recent progress in evaluation of dynamic knee laxity through utilization of the pivot shift test. A thorough electronic search was performed and relevant studies were assessed. Certain dynamic knee laxity measurement methods have been present for over 10 years (Navigation system, Electromagnetic sensor system) while other methods (Inertial sensor, Image analysis system) have been introduced recently. Methods to evaluate dynamic knee laxity through the pivot shift test are already potent. However, further refinement is warranted. In addition, to correctly quantify the pivot shift test, the involved forces need to be controlled through either standardization or mechanization of the pivot shift test.