Biomechanics of rotational instability and anatomic anterior cruciate ligament 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.

Is combined robotically assisted unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction a good solution for the young arthritic knee?

PURPOSE

Anterior cruciate ligament (ACL) deficiency can be a consequence or a cause of femoro-tibial osteoarthritis (OA). Several studies have published satisfactory outcomes of unicompartimental knee arthroplasty (UKA) and combined ACL reconstruction despite its absence classically being considered a contraindication. A major challenge in the ACL deficient knee is obtaining appropriate gap balancing and limb axis. Robotically assisted UKA allows for precise control of these factors; however, it's utilisation as a tool with combined ACL reconstruction and UKA has not been described. The purpose of this study was to evaluate the clinical and radiological outcomes of robotically assisted UKA with combined ACL reconstruction.

METHODS

This was a retrospective single-centre study of ten patients operated by a single surgeon from 2016 to 2020. All surgery was performed using a cemented fixed bearing UKA prosthesis (Journey uni, Smith and Nephew®) (8 medial, 2 lateral) inserted with the assistance of an image-free robotic-assisted system (BlueBelt, Navio, Smith and Nephew®). All ACL reconstructions were performed using hamstring autograft. Clinical assessment included International Knee Score (IKS) score, Tegner score and patient satisfaction. Radiological assessment was performed to assess radiolucent lines, progression of OA in the other compartments, Hip-Knee-Ankle angle and Posterior Tibial Slope.

RESULTS

There were eight females (80%), mean age was 57 ± 7 [48-70], mean BMI was 26 ± 3 [22-31]. The mean follow-up was 45 months ± 13 months [24-66]. Mean post-operative IKS knee and function score were respectively 96 ± 4.5 [88-100] and 93 ± 8.2 [74-100], mean Tegner score was 4.5 ± 1.4 [3-6]. Nine patients (90%) returned to sport; one patient (10%) was dissatisfied because of residual pain preventing a return to a desired level of sport. 100% of the radiological objectives were achieved. No radiolucent lines were seen at the last follow-up. There were two re-operations (20%) for stiffness requiring arthroscopic arthrolysis at two and three months respectively following surgery, with full recovery of the flexion at the last follow-up in both cases. No other complications were observed.

CONCLUSION

Robotic UKA associated with ACL reconstruction provides satisfactory early patient outcomes and accurate implant positioning. The first results in terms of return to sports were promising.

Towards a validated musculoskeletal knee model to estimate tibiofemoral kinematics and ligament strains: comparison of different anterolateral augmentation procedures combined with isolated ACL reconstructions

BACKGROUND

Isolated ACL reconstructions (ACLR) demonstrate limitations in restoring native knee kinematics. This study investigates the knee mechanics of ACLR plus various anterolateral augmentations using a patient-specific musculoskeletal knee model.

MATERIALS AND METHODS

A patient-specific knee model was developed in OpenSim using contact surfaces and ligament details derived from MRI and CT data. The contact geometry and ligament parameters were varied until the predicted knee angles for intact and ACL-sectioned models were validated against cadaveric test data for that same specimen. Musculoskeletal models of the ACLR combined with various anterolateral augmentations were then simulated. Knee angles were compared between these reconstruction models to determine which technique best matched the intact kinematics. Also, ligament strains calculated by the validated knee model were compared to those of the OpenSim model driven by experimental data. The accuracy of the results was assessed by calculating the normalised RMS error (NRMSE); an NRMSE < 30% was considered acceptable.

RESULTS

All rotations and translations predicted by the knee model were acceptable when compared to the cadaveric data (NRMSE < 30%), except for the anterior/posterior translation (NRMSE > 60%). Similar errors were observed between ACL strain results (NRMSE > 60%). Other ligament comparisons were acceptable. All ACLR plus anterolateral augmentation models restored kinematics toward the intact state, with ACLR plus anterolateral ligament reconstruction (ACLR + ALLR) achieving the best match and the greatest strain reduction in ACL, PCL, MCL, and DMCL.

CONCLUSION

The intact and ACL-sectioned models were validated against cadaveric experimental results for all rotations. It is acknowledged that the validation criteria are very lenient; further refinement is required for improved validation. The results indicate that anterolateral augmentation moves the kinematics closer to the intact knee state; combined ACLR and ALLR provide the best outcome for this specimen.

Anterior Cruciate Ligament Reconstruction with Autologous Hamstring Single- versus Double-Bundle Graft: A Prospective Study with 10-Year Follow-up

The purpose of the present study was to compare the clinical and subjective outcomes of anterior cruciate ligament (ACL) reconstruction using an autologous hamstring double bundle (DB) with a single bundle (SB) after a 10-year follow-up. A prospective comparative cohort study was performed of 47 consecutive patients with ACL rupture included between May 2006 and March 2008. Inclusion criteria were less than 2 years since the injury date, no previous surgery on the affected knee, and having closed growth plates. Patients were divided into two groups: (1) SB group (n = 25) and (2) DB group (n = 22). Patients underwent evaluation before surgery and at 1 and 10 years postoperatively. The clinical evaluation included the International Knee Documentation Committee (IKDC) Questionnaire, pivot shift test, and single hop test, as well as X-rays (anterior drawer X-rays on a Telos stress radiography). Range of motion (ROM) was assessed at 10-year follow-up. Both groups were similar in terms of baseline characteristics. Post hoc power analysis showed that among 30 and 226 patients would be needed for statistical significance, depending on the outcome. With the numbers available, no significant differences were observed in subjective IKDC, anterior stability (measured with Telos), and functional test outcomes (single hop test) between both groups at 1 and 10 years postoperatively. Regarding rotational instability (pivot-shift test), DB group was significantly superior (p = 0.002). Regarding ROM, no significant differences were observed between groups. No failure was registered in any of the groups. ACL reconstruction (ACLR) with an autologous hamstring, both with bundles and DB, shows overall better outcomes compared with the status before surgery. DB ACLR provides better rotational control of the knee, an outcome that is maintained after 10 years.

Anterolateral Extraarticular Stabilisation of the Knee: Modified Lemaire Procedure

The anterolateral aspect of the knee is prone to laxity or symptomatic instability, if the anterior cruciate ligament (ACL) is torn. It is necessary to address this issue in patients with general joint hyperlaxity, overextension of the knee, massive anterolateral instability, or re-tear of the ACL with chronic instability. In these cases, and in addition to a preoperative bony workup and revision ACL reconstruction, anterolateral stabilisation should be considered to avoid persistent anterolateral rotation instability and failure of the ACL reconstruction.To stabilise the anterolateral corner of the knee, the modified Lemaire procedure as presented and illustrated here is a straight forward surgical technique that can be performed right after standard ACL reconstruction surgery, if indicated. It is independent from the graft choice for the ACL reconstruction, and the surgical setting in the operating room remains unchanged.

Tunnel Convergence Rate in Combined Anteromedial Portal Anterior Cruciate Ligament and Anterolateral Structure Reconstructions Is Influenced by Anterior Cruciate Ligament Knee Flexion Angle, Tunnel Position, and Direction

PURPOSE

The goal of the present study was to evaluate a potential tunnel convergence in combined anterior cruciate ligament (ACL) reconstruction using the anteromedial portal technique and lateral extra-articular tenodesis (LET).

METHODS

Ten fresh frozen femora were dissected and a K-wires were inserted into the middle of the ACL stump, according to an ACL reconstruction at 110° and 140° knee flexion. ACL reconstruction at 120° and 130° was simulated. Seven K-wires with different femoral insertion sites and angulations were drilled into the lateral femoral condyle relative to the lateral epicondyle (E3: 8 mm proximal and 4 mm posterior; E1: 5 mm proximal and 5 mm anterior and E2: over-the-top position). Tunnel conflict rate was evaluated using a measuring arm and a metrology software.

RESULTS

Drilling the femoral ACL tunnel in low knee flexion (110°-120°) significantly (P < .001) reduced the tunnel conflict rate compared to the ACL drilled in high knee flexion (130°-140°). Changing the insertion point from proximal and posterior (E3) to proximal and anterior (E1) showed a reduced tunnel conflict rate from 40 ± 21.2% to 15 ± 26% and no tunnel conflict for an ACL drilled at 110°-130° knee flexion.

CONCLUSION

A possible tunnel conflict in simultaneous ACL reconstruction using the AMP technique and LET was dependent on ACL knee flexion angle, LET insertion site, and angulation. This posed the dilemma that no generally applicable LET configuration could be recommended to avoid a tunnel conflict. However, it appears that an insertion point located proximal and anterior to the lateral epicondyle results in less tunnel conflicts than an insertion point located proximal and posterior.

CLINICAL RELEVANCE

An insertion point located proximal and anterior to the lateral epicondyle with a 30° proximal and 30° anterior angulation could reliably avoid a tunnel conflict when the ACL was drilled between 110 and 130° using a low anteromedial portal.

The superficial medial collateral ligament is the major restraint to anteromedial instability of the knee

PURPOSE

The purpose of the present study was to determine how the medial structures and ACL contribute to restraining anteromedial instability of the knee.

METHODS

Twenty-eight paired, fresh-frozen human cadaveric knees were tested in a six-degree of freedom robotic setup. After sequentially cutting the dMCL, sMCL, POL and ACL in four different cutting orders, the following simulated clinical laxity tests were applied at 0°, 30°, 60° and 90° of knee flexion: 4 Nm external tibial rotation (ER), 4 Nm internal tibial rotation (IR), 8 Nm valgus rotation (VR) and anteromedial rotation (AMR)-combined 89 N anterior tibial translation and 4 Nm ER. Knee kinematics were recorded in the intact state and after each cut using an optical tracking system. Differences in medial compartment translation (AMT) and tibial rotation (AMR, ER, IR, VR) from the intact state were then analyzed.

RESULTS

The sMCL was the most important restraint to AMR, ER and VR at all flexion angles. Release of the proximal tibial attachment of the sMCL caused no significant increase in laxity if the distal sMCL attachment remained intact. The dMCL was a minor restraint to AMT and ER. The POL controlled IR and was a minor restraint to AMT and ER near extension. The ACL contributed with the sMCL in restraining AMT and was a secondary restraint to ER and VR in the MCL deficient knee.

CONCLUSION

The sMCL appears to be the most important restraint to anteromedial instability; the dMCL and POL play more minor roles. Based on the present data a new classification of anteromedial instability is proposed, which may support clinical examination and treatment decision. In higher grades of anteromedial instability an injury to the sMCL should be suspected and addressed if treated surgically.

Plantaris tendon: a novel graft for anterolateral ligament reconstruction and additional reinforcement for anterior cruciate ligament autografts in combined reconstructive procedures

The anterolateral ligament is recently recognized as an important structure in restoring rotational stability of the anterior cruciate ligament-deficient knee. Biomechanical and clinical studies confirmed the benefits of concurrent anterior cruciate ligament and anterolateral ligament reconstruction. However, present techniques mostly use hamstring tendons autografts and therefore additionally disrupt the knee biomechanics. The plantaris tendon is a well known and accessible graft and has excellent biomechanical properties for anterolateral ligament reconstruction. The present paper describes a new combined anterior cruciate ligament and anterolateral ligament reconstruction technique using plantaris tendon and semitendinosus tendon.Level of evidence V (Case report).

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).

Side Variations of Anterior Cruciate Ligament Coronal Angles: Implications for ACL Reconstruction

Current literature has shown a biomechanical advantage of recreating the native coronal obliquity of the anterior cruciate ligament (ACL) during grating procedures; however, the majority of studies on ACL morphological variation have been performed unilaterally. This cadaveric study aimed to evaluate sided ACL coronal angle of inclination variation including trend analysis with sex, age, height, and femoral condyle width. The ACLs of 57 embalmed cadaveric specimens were evaluated bilaterally for a total of 114 ACLs. The knees were flexed to 110°. A 0.70-mm wire measured coronal angulation through the lateral tibial plateau and the medial ACL border. An image taken of the wire allowed digital measurement with the ImageJ software. IBM SPSS was utilized for statistical analysis. Bilateral measurements demonstrated a difference in an individual's sided ACL angulation (P < 0.001). Right-sided angulation was greater in 61.4% (35/57). In cadavers with greater right-side angulation, right ACLs averaged 66.2° versus left ACLs averaged 60.9° (P < 0.001). Cadavers with greater left-sided ACL angles demonstrated average left ACLs measuring 65.5° versus right ACLs measuring 60.6° (P < 0.001). Right-sided angles were greater in 69.7% of females. Understanding the anatomy of the ACL's native coronal angle and variations between a patient's knees is imperative during reconstruction surgery to aid in anatomic tunnel placement for improved knee motion and rotational knee kinematics following surgery. A statistically significant difference exists between an individual's right and left ACL coronal angles of inclination. Clin. Anat. 32:1102-1106, 2019. © 2019 Wiley Periodicals, Inc.

Contribution of Additional Anterolateral Structure Augmentation to Controlling Pivot Shift in Anterior Cruciate Ligament Reconstruction

BACKGROUND

Several types of anterolateral structure (ALS) augmentation procedures in anterior cruciate ligament (ACL) reconstruction have been reported. However, information is limited regarding the effect of additional ALS augmentation on rotatory stability in a clinical setting.

PURPOSE/HYPOTHESIS

This study aimed to investigate the contribution of additional ALS augmentation in ACL reconstruction in cases with a high risk of residual pivot shift. The 2 hypotheses were as follows. First, additional ALS augmentation would improve rotatory stability as compared with solely reconstructing the ACL. Second, graft tension changes would be different between the ACL and ALS during knee range of motion and against anterior or rotatory loads.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifteen patients who met at least 1 of the following criteria were included: (1) revision ACL reconstruction, (2) preoperative high-grade pivot shift, or (3) hyperextended knee. The pivot-shift test was performed preoperatively and during surgery after ACL reconstruction and after additional ALS augmentation with acceleration measurements from a triaxial accelerometer. The tension changes of the ACL and ALS grafts were also measured during knee range of motion and against manual maximum anterior tibial translation, internal rotation, and external rotation.

RESULTS

After ACL reconstruction, the pivot-shift acceleration was still greater than that of the uninjured knee. However, additional ALS augmentation further reduced acceleration when compared with ACL reconstruction alone in both primary and revision cases (P < .05 vs preoperative, P < .05 vs ACL). During knee flexion-extension, the tension of the ACL increased as the knee was extended, whereas that of the ALS did not change. Graft tension of the ACL and ALS became higher with internal rotation and lower with external rotation as compared with the neutral position. Tension of the ACL was significantly increased against anterior tibial translational loads, whereas that of the ALS was not.

CONCLUSION

Additional ALS augmentation further improved the rotatory stability during ACL reconstruction in patients with a high risk of residual pivot shift at the time of surgery. Significant differences in graft tension changes were also observed between the ACL and ALS against different loads. Additional ALS augmentation may be considered to eliminate the pivot shift in patients with a high risk of residual pivot shift.

Lateral extra-articular reconstruction length changes during weightbearing knee flexion and pivot shift: A simulation study

INTRODUCTION

Variations in the length of lateral extra-articular reconstruction (LER) have been widely investigated during knee flexion but there is no information about length changes during pivot shift. This study sought to assess the changes in LER tension during weightbearing knee flexion in a normal knee and in a computer-simulated pivot-shift scenario.

HYPOTHESIS

Placing the femoral tunnel posterior and proximal to the lateral femoral epicondyle allows the LER to tighten early in the flexion range during weightbearing (squatting motion) and simulated pivot-shift.

MATERIAL AND METHODS

A computer model was used to simulate weightbearing knee flexion and pivot shift scenarios. Changes in LER tension were calculated in both scenarios by estimating the distance between six femoral attachment sites (posterior and proximal to the lateral femoral epicondyle) and two tibial tunnel locations: Gerdy's tubercle (GT) and the anterolateral ligament (ALL) anatomic attachment site.

RESULTS

Independent of the location of the femoral and tibial tunnels, the LER tightened by up to 22% of its resting length during the early portion of weightbearing knee flexion and then relaxed from 40° to 60° of knee flexion. The ALL tibial tunnel position allowed complete LER relaxation at 60° flexion whereas LER using the GT tibial tunnel position remained tighter. In the simulated pivot-shift test, and for all femoral tunnel locations, the LER tightened by 20% to 34% of its resting value for the GT tibial tunnel position and by 11% to 26% for the ALL tibial tunnel position.

DISCUSSION

During weightbearing knee flexion, placing the femoral tunnel proximal and posterior to the femoral epicondyle was associated with LER tightening in the early degrees of flexion and LER relaxation between 40 and 60° flexion. LER tightening occurred during a simulated pivot-shift test supporting the concept that a posterior and proximal femoral LER tunnel position is most effective during weightbearing knee flexion and altered knee kinematics.

Anterolateral ligament as a main stabilizing structure оf rotational stability оf the knee joint

Currently, anterior cruciate ligament grafting is one of the most popular operations on the knee joint, but despite the fact that the technique has been used for years, there is a high percentage of unsatisfactory long-term postoperative results, reaching 25%, according to various authors. The concern over this problem has led to an increase in the number of studies aimed at the understanding of the causes of these failures. Most researchers have concluded that the unsatisfactory results are associated with instability in the knee joint, which is caused by the damage of a ligamentous structure found in many dissections, namely, anterolateral ligament (ALL). In this literature review, we have analyzed the articles dedicated to the ALL, its anatomical and histological structure, its biomechanics, as well as its role in the anterolateral stability of the joint. Also in this review we consider the existing surgical methods for the correction of anterolateral instability associated with the ALL damage.

Single-tunnel anatomic double-bundle anterior cruciate ligament reconstruction has the same effectiveness as double femoral, double tibial tunnel: A prospective randomized study

PURPOSE

To investigate whether single femoral, single tibial tunnel anatomic double-bundle anterior cruciate ligament (ACL) reconstruction is equal to or superior to double femoral, double tibial tunnel ACL double-bundle anatomic reconstruction in terms of restoring the stability and functions of the knee joint.

METHODS

A prospective clinical study was performed to compare 30 cases of single-tunnel ACL double-bundle anatomic reconstruction to 28 cases of double-tunnel ACL double-bundle anatomic reconstruction, with average follow-up of 36 months. All graft tendons were hamstring tendon autografts. Tunnel placements in all the cases were made anatomically. Clinical results were collected after reconstruction. Graft appearance, meniscus status and cartilage state under arthroscopy were compared and analyzed.

RESULTS

Tunnel placements were in the anatomic positions in both groups. On the lateral pivot-shift test performed at 36 months postoperatively, there was no significant difference between groups. Clinical results such as International Knee Documentation Committee score, Tegner activity scale, and range of motion showed no significant differences between the groups. The mean thickness of anteromedial graft was reduced by 10.3% and that of the posterolateral graft was reduced by 11.1% from the original graft thickness evaluated by magnetic resonance imaging. No new meniscal tears were found either group; however, cartilage damage occurred in the double-tunnel group at 39.3%, and this rate was significantly higher than that in the single-tunnel group (10.0%).

CONCLUSION

Single femoral, single tibial tunnel anatomic double-bundle ACL reconstruction has the same effectiveness as the double femoral, double tibial tunnel in restoring the knee's stability and functions.

Between-Limb Symmetry during Double-Leg Vertical Hop Landing in Males an Average of Two Years after ACL Reconstruction is Highly Correlated with Postoperative Physiotherapy Supervision Duration

This study investigates whether double-leg and single-leg vertical hops (VH) landing between-limb symmetry in males, an average of two years after anterior cruciate ligament (ACL) reconstruction (ACLR), is associated with postoperative physiotherapy supervision duration. Thirty-eight healthy controls and thirty-eight males after primary unilateral ACLR, with the use of ipsilateral semitendinosus and gracilis tendon autograft, on average two years before, underwent bilateral peak vertical ground reaction force (vGRF) measurements during double-leg and single-leg VH landing, using two force plates. The vGRF was normalized to the body mass (vGRF BM). The vGRF BM limb symmetry index (LSI) was calculated. Tests for dependent and independent samples and linear Pearson’s correlation coefficient (r) calculations were performed. There were significant between-leg differences in the double-leg (p < 0.001) vGRF BM values. The longer the postoperative physiotherapy supervision duration was, the higher the double-leg VH LSI values (r = 0.727; p < 0.001). There was also a significant but weak positive association between the single-leg VH landing LSI value and the physiotherapy supervision duration (r = 0.333; p = 0.041). Between-limb symmetry during double-leg VH landing in males, an average of two years after ACLR, was correlated with postoperative physiotherapy supervision duration. Fully supervised postoperative physiotherapy for a minimum of six months is more effective for improving VH landing limb symmetry in patients after ACLR.

Development and validation of a robotic system for ankle joint testing

Ankle sprains are the most common sports injury. Gaining a better understanding of ankle mechanics will help improve current treatments, enabling a better quality of life for patients following surgery. In this paper, the development of a robotic system for ankle joint testing is presented. It is composed of an industrial robot, a universal force/torque sensor and bespoke holders allowing high repositioning of specimens. A specimen preparation protocol that uses optical tracking to register the ankle specimens is used. A registration technique is applied to define and calibrate the task related coordinate system needed to control the joint's degrees of freedom and to simulate standardised, clinical ankle laxity tests. Experiments were carried out at different flexion angles using the robotic platform. Optical tracking was used to record the resulting motion of the tibia for every simulated test. The measurements from the optical tracker and the robot were compared and used to validate the system. These findings showed that the optical tracking measurements validate those from the robot for ankle joint testing with interclass coefficients equal to 0.991, 0.996 and 0.999 for the anterior-posterior translations, internal-external and inversion-eversion rotations.

Influence of the Anterolateral Ligament on Knee Laxity: A Biomechanical Cadaveric Study Measuring Knee Kinematics in 6 Degrees of Freedom Using Dynamic Radiostereometric Analysis

Background:

An anterior cruciate ligament (ACL) rupture often occurs during rotational trauma to the knee and may be associated with damage to extracapsular knee rotation–stabilizing structures such as the anterolateral ligament (ALL).

Purpose:

To investigate ex vivo knee laxity in 6 degrees of freedom with and without ALL reconstruction as a supplement to ACL reconstruction.

Study Design:

Controlled laboratory study.

Methods:

Cadaveric knees (N = 8) were analyzed using dynamic radiostereometry during a controlled pivotlike dynamic movement simulated by motorized knee flexion (0° to 60°) with 4-N·m internal rotation torque. We tested the cadaveric specimens in 5 successive ligament situations: intact, ACL lesion, ACL + ALL lesion, ACL reconstruction, and ACL + ALL reconstruction. Anatomic single-bundle reconstruction methods were used for both the ACL and the ALL, with a bone-tendon quadriceps autograft and gracilis tendon autograft, respectively. Three-dimensional kinematics and articular surface interactions were used to determine knee laxity.

Results:

For the entire knee flexion motion, an ACL + ALL lesion increased the mean knee laxity (P < .005) for internal rotation (2.54°), anterior translation (1.68 mm), and varus rotation (0.53°). Augmented ALL reconstruction reduced knee laxity for anterior translation (P = .003) and varus rotation (P = .047) compared with ACL + ALL–deficient knees. Knees with ACL + ALL lesions had more internal rotation (P < .001) and anterior translation (P < .045) at knee flexion angles below 40° and 30°, respectively, compared with healthy knees. Combined ACL + ALL reconstruction did not completely restore native kinematics/laxity at flexion angles below 10° for anterior translation and below 20° for internal rotation (P < .035). ACL + ALL reconstruction was not found to overconstrain the knee joint.

Conclusion:

Augmented ALL reconstruction with ACL reconstruction in a cadaveric setting reduces internal rotation, varus rotation, and anterior translation knee laxity similar to knee kinematics with intact ligaments, except at knee flexion angles between 0° and 20°.

Clinical Relevance:

Patients with ACL injuries can potentially achieve better results with augmented ALL reconstruction along with ACL reconstruction than with stand-alone ACL reconstruction. Furthermore, dynamic radiostereometry provides the opportunity to examine clinical patients and compare the recontructed knee with the contralateral knee in 6 degrees of freedom.

Anatomic and non-anatomic anterior cruciate ligament posterolateral bundle augmentation affects graft function

PURPOSE

The purpose of this study is to compare knee laxity and graft function (tissue force) between anatomic and non-anatomic posterolateral (PL) bundle augmentation.

METHODS

Twelve (n = 12) fresh-frozen mature, unpaired porcine knees were tested using a robotic testing system. Four knee states were compared: (a) intact anterior cruciate ligament (ACL), (b) deficient PL and intermediate bundles, (c) anatomic PL augmentation, and (d) non-anatomic PL augmentation. Anterior tibial translation (ATT), internal rotation (IR) and external rotation (ER), and the in situ tissue force were measured under an 89.0-N anterior tibial load and 4.0-N m internal and external tibial torques.

RESULTS

Both anatomic and non-anatomic PL augmentation restored the ER, IR, and ATT of the intact knee at all knee flexion angles (n.s.). Both anatomic and non-anatomic PL augmentation restored the in situ tissue force of the ACL during ER and IR loading and ATT loading at all knee flexion angles except at 60° of knee flexion, where the non-anatomic PL augmentation did not restore the in situ tissue force of the ACL during external rotation loading and the anatomic PL augmentation did not restore the in situ tissue force of the ACL during IR loading. Furthermore, there were no differences in ATT, IR, ER, and in situ tissue force under anterior tibial loading, IR and ER loading between the two reconstruction groups.

CONCLUSION

There were no significant differences between anatomic and non-anatomic PL augmentation using the porcine knee model.

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.

Clinical outcomes of extra-articular tenodesis/anterolateral reconstruction in the ACL injured knee

PURPOSE

The role of concomitant extra-articular procedures in improving the outcome of ACL reconstruction has experienced a recent resurgence in interest. The aim of this article is to highlight the differences in philosophies and outcomes of historical lateral extra-articular tenodesis (LET) and contemporary, anterolateral reconstruction.

METHODS

A narrative review was performed using PubMed/MEDLINE using the keywords "lateral extra-articular tenodesis" and "anterolateral ligament reconstruction".

RESULTS

Results of search strategy: Thirty-seven studies [13 reporting clinical outcomes of isolated LET in ACL deficient knees and 24 comparing isolated anterior cruciate ligament reconstruction (ACLR) with ACLR + LET] and 1 study on anterolateral ligament (ALL) reconstruction were identified as relevant and included in the review. Results of literature review: Isolated extra-articular reconstructions are rarely performed in contemporary practice. They are associated with a high rate of persistent anterior instability and early degenerative change. Combined ACL reconstruction and lateral extra-articular tenodeses results in a significant reduction in the prevalence of residual pivot shift, but the majority of the studies do not demonstrate any significant difference with respect to patient-reported outcome measures and return to sport. Although several authors report a trend towards decreased graft rupture rates, significant differences were not demonstrated in most studies. In a single clinical study, combined anatomic ACL and anterolateral ligament reconstruction was reported to be associated with a threefold reduction in graft rupture rates and improved return to sport compared to isolated ACL graft choices.

CONCLUSIONS

Historically performed, combined ACL reconstruction and lateral extra-articular tenodeses are associated with improved knee kinematics. Although trends towards decreased graft rupture rates are reported by several authors, the majority did not demonstrate a significant difference, likely as a result of small and underpowered studies using post-operative immobilisation and delayed rehabilitation protocols. More recently, combined ACLR and ALL reconstruction has been shown to be associated with significant improvements in graft failure and return to sport rates when compared to isolated ACLR. However, these results are from a single clinical series with only medium-term follow-up.

LEVEL OF EVIDENCE

IV.

Activation of biceps femoris long head reduces tibiofemoral anterior shear force and tibial internal rotation torque in healthy subjects

The anterior cruciate ligament (ACL) provides resistance to tibial internal rotation torque and anterior shear at the knee. ACL deficiency results in knee instability. Optimisation of muscle contraction through functional electrical stimulation (FES) offers the prospect of mitigating the destabilising effects of ACL deficiency. The hypothesis of this study is that activation of the biceps femoris long head (BFLH) reduces the tibial internal rotation torque and the anterior shear force at the knee. Gait data of twelve healthy subjects were measured with and without the application of FES and taken as inputs to a computational musculoskeletal model. The model was used to investigate the optimum levels of BFLH activation during FES gait in reducing the anterior shear force to zero. This study found that FES significantly reduced the tibial internal rotation torque at the knee during the stance phase of gait (p = 0.0322) and the computational musculoskeletal modelling revealed that a mean BFLH activation of 20.8% (±8.4%) could reduce the anterior shear force to zero. At the time frame when the anterior shear force was zero, the internal rotation torque was reduced by 0.023 ± 0.0167 Nm/BW, with a mean 188% reduction across subjects (p = 0.0002). In conclusion, activation of the BFLH is able to reduce the tibial internal rotation torque and the anterior shear force at the knee in healthy control subjects. This should be tested on ACL deficient subject to consider its effect in mitigating instability due to ligament deficiency. In future clinical practice, activating the BFLH may be used to protect ACL reconstructions during post-operative rehabilitation, assist with residual instabilities post reconstruction, and reduce the need for ACL reconstruction surgery in some cases.

ACL-reconstructed and ACL-deficient individuals show differentiated trunk, hip, and knee kinematics during vertical hops more than 20 years post-injury

PURPOSE

Little is known regarding movement strategies in the long term following injury of the anterior cruciate ligament (ACL), and even less about comparisons of reconstructed and deficient knees in relation to healthy controls. The present purpose was to compare trunk, hip, and knee kinematics during a one-leg vertical hop (VH) ~20 years post-ACL injury between persons treated with surgery and physiotherapy (ACL_R), solely physiotherapy (ACL_PT), and controls (CTRL). Between-leg kinematic differences within groups were also investigated.

METHODS

Sixty-six persons who suffered unilateral ACL injury on average 23 ± 2 years ago (32 ACL_R, 34 ACL_PT) and 33 controls performed the VH. Peak trunk, hip, and knee angles during Take-off and Landing phases recorded with a 3D motion capture system were analysed with multivariate statistics.

RESULTS

Significant group effects during both Take-off and Landing were found, with ACL_PT differing from CTRL in Take-off with a combination of less knee flexion and knee internal rotation, and from both ACL_R and CTRL in Landing with less hip and knee flexion, knee internal rotation, and greater hip adduction. ACL_R also presented different kinematics to ACL_PT and CTRL in Take-off with a combination of greater trunk flexion, hip flexion, hip internal rotation, and less knee abduction, and in Landing with greater trunk flexion and hip internal rotation. Further, different kinematics and hop height were found between legs within groups in both Take-off and Landing for both ACL groups, but not for CTRL.

CONCLUSION

Different kinematics for the injured leg for both ACL groups compared to CTRL and between treatment groups, as well as between legs within treatment groups, indicate long-term consequences of injury. Compensatory mechanisms for knee protection seem to prevail over time irrespective of initial treatment, possibly increasing the risk of re-injury and triggering the development of osteoarthritis. Detailed investigation of movement strategies during the VH provides important information and a more comprehensive evaluation of knee function than merely hop height. More attention should also be given to the trunk and hip in clinics when evaluating movement strategies after ACL injury.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Biomechanics of the Anterolateral Structures of the Knee

This article describes the complex anatomic structures that pass across the lateral aspect of the knee, particularly the iliotibial tract and the underlying anterolateral ligament and capsule. It provides data on their strength and roles in controlling tibiofemoral joint laxity and stability. These findings are discussed in relation to surgery to repair or reconstruct the anatomic structures, or to create tenodeses with similar effect.

Reoperation Rates After Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction: A Series of 548 Patients From the SANTI Study Group With a Minimum Follow-up of 2 Years

BACKGROUND

Early clinical results of anterolateral ligament (ALL) reconstruction are promising, but concerns exist due to high rates of complications after other types of lateral extra-articular tenodesis. The rate of surgery after combined anterior cruciate ligament (ACL) and ALL reconstruction is not known.

PURPOSE

To determine the rate of reoperation after combined ACL and ALL reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective analysis of prospectively collected data from the Scientific ACL Network International (SANTI) Study Group database was performed to include all patients who had undergone combined ACL and ALL reconstruction between January 2012 and June 2014. At the end of the study period, all patients were contacted by telephone, and the operative notes of those who stated that they had undergone reoperation were reviewed to determine the type and rates of the subsequent procedures performed. Descriptive data were analyzed for the entire patient cohort.

RESULTS

The study population comprised 548 quadruple hamstring graft (4HT)+ALL reconstructions. The mean age (±SD) was 24.3 ± 7.9 years (range, 11.9-55.7 years), and 70.3% of subjects were male. The mean duration of follow-up was 35.5 ± 8.0 months (range, 24-54 months). Seventy-two patients (13.1%) underwent ipsilateral reoperation. This comprised a total of 77 procedures. Graft revision occurred in 14 knees (2.6%) at a mean of 18.3 months (±7.4 months) after the index procedure. There were 63 reoperations for ipsilateral, non-graft rupture-related indications (meniscus, n = 30; arthrofibrosis, n = 22; removal of hardware, n = 4; deep infection, n = 3; arthroscopic lavage without infection, n = 4). The only specific complications related to the ALL procedure (n = 3) were all related to femoral hardware that required removal. In both univariate and multivariate analyses, only the presence of a medial meniscal lesion at the index procedure was significantly associated with ipsilateral reoperation (odds ratio, 2.58; 95% CI, 1.43-4.76; P = .002).

CONCLUSION

The reoperation rate after combined ACL and ALL reconstruction in this series is broadly comparable to the reoperation rate after isolated ACL reconstruction as reported in previous studies. In addition, the high rates of knee stiffness and reoperation reported in historical series of nonanatomic, lateral extra-articular tenodesis were not observed in the current series.

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

PURPOSE

Quantifying the effects of anterior cruciate ligament (ACL) deficiency on knee joint laxity is fundamental for understanding the outcomes of its reconstruction techniques. The general aim of this study was to determine intra-operatively the main modifications in knee laxity before and after standard isolated intra-articular and additional extra-articular anterolateral reinforcement. Our main hypothesis was that laxity abnormalities, particularly axial rotation, can still result from these ACL reconstruction techniques.

METHODS

Thirty-two patients with primary ACL deficiency were analysed by a navigation system immediately before and after each of the two reconstructions. Laxity measurements in terms of knee translations and rotations were taken during the anteroposterior drawer test, with internal-external rotation at 20° and 90° of flexion, and varus-valgus and pivot-shift tests. All these laxity measures were also taken originally from the contralateral healthy knee.

RESULTS

With respect to the contralateral healthy knee, in the ACL-deficient knee significantly increased laxity (expressed in %) was found in the medial compared with that of the lateral compartment, respectively, 115 and 68 % in the drawer test at 20° flexion, and 55 and 46 % at 90° flexion. In the medial compartment, a significant 35 % increment was also observed for the coupled tibial anteroposterior translation during axial knee rotation at 20° of flexion. After isolated intra-articular reconstruction, normal values of anteroposterior laxity were found restored in the pivot-shift and drawer tests in the lateral compartment, but not fully in the medial compartment. After the reinforcement, laxity in the medial compartment was also found restored in the axial rotation test at 20° flexion.

CONCLUSION

In ACL reconstruction, with respect to the contralateral knee, intra-articular plus additional anterolateral reinforcement procedures do not restore normal joint laxity. This combined procedure over-constrained the lateral compartment, while excessive laxity still persists at the medial one.

LEVEL OF EVIDENCE

III.

Incidence and MRI characterization of the spectrum of posterolateral corner injuries occurring in association with ACL rupture

OBJECTIVE

To determine the incidence and MRI characteristics of the spectrum of posterolateral corner (PLC) injuries occurring in association with anterior cruciate ligament (ACL) rupture.

MATERIALS AND METHODS

We carried out a level IV, retrospective case series study. All patients clinically diagnosed with an ACL rupture between July 2015 and June 2016 who underwent MRI of the knee were included in the study. In addition to standard MRI knee reporting, emphasis was placed on identifying injury to the PLC and a description of involvement of these structures by two musculoskeletal radiologists. Association with PLC involvement was sought with concomitant injuries using correlation analysis and logistic regression.

RESULTS

One hundred sixty-two patients with MRI following ACL rupture were evaluated. Thirty-two patients (19.7%) had an injury to at least one structure of the PLC, including the inferior popliteomeniscal fascicle (n = 28), arcuate ligament (n = 20), popliteus tendon (n = 20), superior popliteomeniscal fascicle (n = 18), lateral collateral ligament (n = 8), popliteofibular ligament (n = 7), biceps tendon (n = 4), iliotibial band (n = 3), and fabellofibular ligament (n = 1). Seventy-five percent of all patients with combined ACL and PLC injuries had bone contusions involving the lateral compartment of the knee. The presence of these contusions strongly correlated with superior popliteomeniscal fascicle lesions (p < 0.05). There was no correlation between injuries to other structures of the PLC and other intra-articular lesions.

CONCLUSION

Missed injuries of the PLC lead to considerable morbidity. The relevance of this study is to highlight that these injuries occur more frequently than previously described and that an appropriate index of suspicion, clinical examination, and MRI are all required to reduce the risk of missed diagnoses. The results of this study support previous suggestions that the rate of concomitant PLC injury in the ACL-deficient knee is under-reported. The rate of combined injuries in this series was 19.7%. The key message of this paper is that PLC injury is common in the presence of ACL injury and should be sought both clinically and radiologically.

The effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in single-bundle anatomic ACL reconstruction

PURPOSE

The purpose of the current study was to investigate the potential effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in anatomic ACL reconstruction, using an ideal anatomic point as reference and evaluating postoperative tunnel placement based on 3D CT.

METHODS

An experienced ACL surgeon, using the anatomic approach for femoral tunnel placement, relying on intraarticular landmarks and remnants of the torn ACL-and novel to the fluoroscopic assist-was introduced to its use. A prospective series of patients was included where group 1 (without fluoroscopy) and group 2 (with fluoroscopy) both had postoperative CT scans so that femoral tunnel position could be evaluated and compared to an ideal tunnel centre based on anatomic studies by using the Bernard and Hertel grid.

RESULTS

Group 2, where fluoroscopy was used, had a mean femoral tunnel that was closer to the ideal anatomic centre than group 1. In the Bernard and Hertel grid, the distance in the high-low axis (y-axis) was found significantly closer (P = 0.001), whilst the deep-shallow axis (x-axis) and a total absolute distance were not significantly closer to the ideal described anatomic centre.

CONCLUSIONS

Intraoperative fluoroscopy was found effective as an aid for placing the femoral tunnel in a more accurate position, as compared to a desired anatomic centre. Although the concept of the "one-size-fits-all" approach for tunnel placement is debatable, the avoidance of grossly misplaced tunnels is the benefit of using fluoroscopy during ACL reconstruction. The authors hold that fluoroscopy is readily available, safe and easy to use and therefore a good aid in the anatomic approach for graft tunnel placement, for example, in a learning situation, in revision cases and when performing low volumes of such surgery.

LEVEL OF EVIDENCE

III.

The Involvement of the Anterolateral Ligament in Rotational Control of the Knee

BACKGROUND

Rotational control of the knee is crucial for knee stability. The anterolateral ligament (ALL) has been identified as a potentially important structure involved in rotational control of the knee.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine, utilizing a navigation system, the involvement of the anterior cruciate ligament (ACL), the iliotibial band (ITB), and the ALL in tibial internal rotational control of the knee. The hypothesis was that the ALL would be involved in rotational control of the knee at varying degrees of knee flexion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve fresh-frozen cadaveric knees were tested in internal rotation at 20° and 90° of flexion and then subsequently tested using a simulated pivot-shift test consisting of coupled axial rotation at 30° of flexion. Serial sectioning of the ACL, ALL, and ITB was performed. On the contralateral knee, sectioning was performed in the reverse order. Measurements were collected using a surgical navigation system before and after each sectioning.

RESULTS

After ACL sectioning, an incision of the ALL induced a significant increase in internal rotation (+19.2% [P = .0002] at 20°; +21.8% [P = .0029] at 90°) and in coupled axial rotation (+43.0%; P = .0035) compared with the intact knee as well as a significant increase in internal rotation at 90° (+13.4%; P = .009) and in coupled axial rotation (+30.8%; P = .0124) compared with the ACL-deficient knee. After ITB sectioning, an additional ALL section caused a significant increase in internal rotation (+39.0% [P = .002] at 20°; +63.0% [P = .0147] at 90°) and in coupled axial rotation (+59.7%; P = .0003) compared with the intact knee as well as a significant increase in internal rotation at 90° (+14.8%; P = .0067) in comparison to the ITB-deficient knee.

CONCLUSION

The ALL is involved in rotational control of the knee at varying degrees of knee flexion and during a simulated pivot shift. Concomitant to an ACL or ITB transection, sectioning the ALL further increased rotational laxity.

CLINICAL RELEVANCE

This laboratory study demonstrated that the ALL provides rotational control of the knee in combination with the ACL and/or ITB.

Biomechanics of the anterior cruciate ligament: Physiology, rupture and reconstruction techniques

The influences and mechanisms of the physiology, rupture and reconstruction of the anterior cruciate ligament (ACL) on kinematics and clinical outcomes have been investigated in many biomechanical and clinical studies over the last several decades. The knee is a complex joint with shifting contact points, pressures and axes that are affected when a ligament is injured. The ACL, as one of the intra-articular ligaments, has a strong influence on the resulting kinematics. Often, other meniscal or ligamentous injuries accompany ACL ruptures and further deteriorate the resulting kinematics and clinical outcomes. Knowing the surgical options, anatomic relations and current evidence to restore ACL function and considering the influence of concomitant injuries on resulting kinematics to restore full function can together help to achieve an optimal outcome.

The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee

BACKGROUND

Anterolateral rotatory instability (ALRI) may result from combined anterior cruciate ligament (ACL) and lateral extra-articular lesions, but the roles of the anterolateral structures remain controversial.

PURPOSE

To determine the contribution of each anterolateral structure and the ACL in restraining simulated clinical laxity in both the intact and ACL-deficient knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 16 knees were tested using a 6 degrees of freedom robot with a universal force-moment sensor. The system automatically defined the path of unloaded flexion/extension. At different flexion angles, anterior-posterior, internal-external, and internal rotational laxity in response to a simulated pivot shift were tested. Eight ACL-intact and 8 ACL-deficient knees were tested. The kinematics of the intact/deficient knee was replayed after transecting/resecting each structure of interest; therefore, the decrease in force/torque reflected the contribution of the transected/resected structure in restraining laxity. Data were analyzed using repeated-measures analyses of variance and paired t tests.

RESULTS

For anterior translation, the intact ACL was clearly the primary restraint. The iliotibial tract (ITT) resisted 31% ± 6% of the drawer force with the ACL cut at 30° of flexion; the anterolateral ligament (ALL) and anterolateral capsule resisted 4%. For internal rotation, the superficial layer of the ITT significantly restrained internal rotation at higher flexion angles: 56% ± 20% and 56% ± 16% at 90° for the ACL-intact and ACL-deficient groups, respectively. The deep layer of the ITT restrained internal rotation at lower flexion angles, with 26% ± 9% and 33% ± 12% at 30° for the ACL-intact and ACL-deficient groups, respectively. The other anterolateral structures provided no significant contribution. During the pivot-shift test, the ITT provided 72% ± 14% of the restraint at 45° for the ACL-deficient group. The ACL and other anterolateral structures made only a small contribution in restraining the pivot shift.

CONCLUSION

The ALL and anterolateral capsule had a minor role in restraining internal rotation; the ITT was the primary restraint at 30° to 90° of flexion.

CLINICAL RELEVANCE

The ITT showed large contributions in restraining anterior subluxation of the lateral tibial plateau and tibial internal rotation, which constitute pathological laxity in ALRI. In cases with ALRI, an ITT injury should be suspected and kept in mind if an extra-articular procedure is performed.

Posteromedial Meniscocapsular Lesions Increase Tibiofemoral Joint Laxity With Anterior Cruciate Ligament Deficiency, and Their Repair Reduces Laxity

BACKGROUND

Injury to the posteromedial meniscocapsular junction has been identified after anterior cruciate ligament (ACL) rupture; however, there is a lack of objective evidence investigating how this affects knee kinematics or whether increased laxity can be restored by repair. Such injury is often overlooked at surgery, with possible compromise to results.

HYPOTHESES

(1) Sectioning the posteromedial meniscocapsular junction in an ACL-deficient knee will result in increased anterior tibial translation and rotation. (2) Isolated ACL reconstruction in the presence of a posteromedial meniscocapsular junction lesion will not restore intact knee laxity. (3) Repair of the posteromedial capsule at the time of ACL reconstruction will reduce tibial translation and rotation to normal. (4) These changes will be clinically detectable.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine cadaveric knees were mounted in a test rig where knee kinematics were recorded from 0° to 100° of flexion by use of an optical tracking system. Measurements were recorded with the following loads: 90-N anterior-posterior tibial forces, 5-N·m internal-external tibial rotation torques, and combined 90-N anterior force and 5-N·m external rotation torque. Manual Rolimeter readings of anterior translation were taken at 30° and 90°. The knees were tested in the following conditions: intact, ACL deficient, ACL deficient and posteromedial meniscocapsular junction sectioned, ACL deficient and posteromedial meniscocapsular junction repaired, ACL patellar tendon reconstruction with posteromedial meniscocapsular junction repair, and ACL reconstructed and capsular lesion re-created. Statistical analysis used repeated-measures analysis of variance and post hoc paired t tests with Bonferroni correction.

RESULTS

Tibial anterior translation and external rotation were both significantly increased compared with the ACL-deficient knee after posterior meniscocapsular sectioning (P < .05). These parameters were restored after ACL reconstruction and meniscocapsular lesion repair (P > .05).

CONCLUSION

Anterior and external rotational laxities were significantly increased after sectioning of the posteromedial meniscocapsular junction in an ACL-deficient knee. These were not restored after ACL reconstruction alone but were restored with ACL reconstruction combined with posterior meniscocapsular repair. Tibial anterior translation changes were clinically detectable by use of the Rolimeter.

CLINICAL RELEVANCE

This study suggests that unrepaired posteromedial meniscocapsular lesions will allow abnormal meniscal and tibiofemoral laxity to persist postoperatively, predisposing the knee to meniscal and articular damage.

Tibial rotation influences anterior knee stability--a robot-aided in-vitro study

BACKGROUND

Anterior cruciate ligament rupture can lead to symptomatic instability, especially during pivoting activities, which are often associated with increased anterior and rotational tibial loading. Therefore, the purpose of our robot-aided in-vitro study was to analyze the influence of tibial rotation on anterior knee stability under three anterior cruciate ligament conditions.

METHODS

Ten human knee specimens were examined using a robotic system. Anterior tibial translations were measured during anterior force application at internally and externally rotated positions of the tibia (5° steps until 4 Nm was reached) at 20°, 60°, and 90° of flexion. The native knee was compared with the knee with deficient and replaced anterior cruciate ligament.

FINDINGS

Tibial rotation significantly influenced anterior tibial translation (P<0.001), with differences of up to 12 mm between the largest and smallest anterior translation in the deficient knee. The largest influence of the anterior cruciate ligament on anterior translation was found in slightly externally rotated positions of the tibia (5°-10° at 20° of flexion; 0°-5° at 90° of flexion). Significantly increased anterior tibial translation (up to 7 mm) was measured after anterior cruciate ligament resection, which could be almost completely restored by the replacement (remaining difference<1mm) over a wide range of tibial rotations.

INTERPRETATION

Tibial rotation clearly influences anterior tibial translation. Because the greatest effect of the anterior cruciate ligament was found in slightly externally rotated positions of the tibia, increased attention to tibial rotation should be paid when performing the Lachman and anterior drawer tests.

Outcome of a Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction Technique With a Minimum 2-Year Follow-up

BACKGROUND

The anterolateral ligament has recently been identified as an important structure involved in rotational laxity after anterior cruciate ligament (ACL) rupture. Results of a combined ACL and anterolateral ligament (ALL) reconstruction technique have never been reported.

PURPOSE

To report subjective and objective outcomes after combined ACL and minimally invasive ALL reconstruction with a minimum 2-year follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 92 patients underwent a combined ACL and ALL reconstruction. Indications for a combined procedure were associated Segond fracture, chronic ACL lesion, grade 3 pivot shift, high level of sporting activity, pivoting sports, and radiographic lateral femoral notch sign. Patients were assessed pre- and postoperatively with objective and subjective International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity scale. Instrumented knee testing was performed with the Rolimeter arthrometer. The Knee injury and Osteoarthritis Outcome Score (KOOS) was obtained at the last follow-up. Complications including graft failure or contralateral ACL rupture were also recorded.

RESULTS

The mean follow-up time was 32.4 ± 3.9 months. One patient (1.1%) was lost to follow-up, 1 patient (1.1%) suffered an ACL graft rupture, and 7 patients (7.6%) had a contralateral ACL rupture, leaving 83 patients for final evaluation. At the last follow-up, all patients had full range of motion. The Lysholm, subjective IKDC, and objective IKDC scores were significantly improved (all P < .0001). The Tegner activity scale at the last follow-up (7.1 ± 1.8) was slightly lower than before surgery (7.3 ± 1.7) (P < .01). The mean differential anterior laxity was 8 ± 1.9 mm before surgery and significantly decreased to 0.7 ± 0.8 mm at the last follow-up (P < .0001). Preoperatively, 41 patients had a grade 1 pivot shift, 23 had a grade 2, and 19 had a grade 3 according to the IKDC criteria. Postoperatively, 76 patients had a negative pivot shift (grade 0), and 7 patients were grade 1 (P < .0001).

CONCLUSION

This study demonstrates that a combined reconstruction can be an effective procedure without specific complications at a minimum follow-up of 2 years. Longer term and comparative follow-up studies are necessary to determine whether these combined reconstructions improve the results of ACL treatment.

Anterior cruciate ligament tears: reconstruction and rehabilitation

Tears of the anterior cruciate ligament (ACL) are common knee injuries experienced by athletes and people with active lifestyles. It is important for members of the healthcare team to take an evidence-based approach to the diagnosis, surgical management, and postoperative rehabilitation of patients with an ACL-deficient knee. Mechanism of ACL injury and diagnostic testing is consistent throughout the literature. Patients frequently opt for ACL reconstruction, and many surgical techniques for ACL reconstruction are available with no clear consensus regarding superiority. Surgeon preference dictates the type of reconstruction and graft choice utilized. No standardized pre- and postoperative rehabilitation protocol exists. However, rehabilitation plays an important role in functional outcomes. A comprehensive rehabilitation program is needed pre- and postoperatively to produce positive patient outcomes.

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.

Anterior cruciate ligament: an anatomical exploration in humans and in a selection of animal species

PURPOSE

Many anatomical anterior cruciate ligament (ACL) studies have indicated that the human ACL is composed of two functional bundles: the antero-medial (AM) and postero-lateral (PL). The purpose of this study is to compare the ACL anatomy among human and assorted animal species.

METHODS

Twenty fresh-frozen knees specimen were used: five humans, ten porcine, one goat, one Kodiak bear, one African lion, one Diana monkey and one Gazelle antelope. All the specimens were dissected to expose the ACL and to visualize the number of bundles and attachment patterns on the tibia and femur. Following the fibre orientation of the individual bundles, a wire loop was used to bluntly separate the bundles starting from the tibial insertion site to the femoral insertion site. In the human and porcine ACL, each bundle was separated into approximately 2 mm diameter segments and then tracked in order to establish the individual bundle's specific pattern of insertion on the femur and tibia.

RESULTS

It appeared that all human and animal knee specimens had three bundles that made up their ACL. In addition, it was noted that among the various specimens species, all viewed with an anterior view, and at 90° knee flexion, the ACL bony insertion sites had similar attachment patterns.

CONCLUSION

In all the specimens, including human, the ACL had three distinct bundles: AM, intermediate (IM) and PL. The bundles were composed of multiple fascicles arranged in a definite order and similar among the different species.

Failure modes and fracture toughness in partially torn ligaments and tendons

Ligaments and tendons are commonly torn during injury, yet the likelihood that untreated initial tears could lead to further tearing or even full rupture has proven challenging to predict. In this work, porcine Achilles tendon and human anterior longitudinal ligament samples were tested using both standard fracture toughness methods and complex loading conditions. Failure modes for each of 14 distinct testing cases were evaluated using a total of 131 soft tissue tests. Results showed that these soft tissues were able to completely resist any further crack propagation of an initial tear, regardless of fiber orientation or applied loading condition. Consequently, the major concern for patients with tendon or ligament tears is likely not reduction in ultimate tissue strength due to stress risers at the tip of the tear, but rather a question of whether or not the remaining cross-section is large enough to support the anticipated loading.

Effect of perturbing a simulated motion on knee and anterior cruciate ligament kinetics

Current surgical treatments for common knee injuries do not restore the normal biomechanics. Among other factors, the abnormal biomechanics increases the susceptibility to the early onset of osteoarthritis. In pursuit of improving long term outcome, investigators must understand normal knee kinematics and corresponding joint and anterior cruciate ligament (ACL) kinetics during the activities of daily living. Our long term research goal is to measure in vivo joint motions for the ovine stifle model and later simulate these motions with a 6 degree of freedom (DOF) robot to measure the corresponding 3D kinetics of the knee and ACL-only joint. Unfortunately, the motion measurement and motion simulation technologies used for our project have associated errors. The objective of this study was to determine how motion measurement and motion recreation error affect knee and ACL-only joint kinetics by perturbing a simulated in vivo motion in each DOF and measuring the corresponding intact knee and ACL-only joint forces and moments. The normal starting position for the motion was perturbed in each degree of freedom by four levels (-0.50, -0.25, 0.25, and 0.50 mm or degrees). Only translational perturbations significantly affected the intact knee and ACL-only joint kinetics. The compression-distraction perturbation had the largest effect on intact knee forces and the anterior-posterior perturbation had the largest effect on the ACL forces. Small translational perturbations can significantly alter intact knee and ACL-only joint forces. Thus, translational motion measurement errors must be reduced to provide a more accurate representation of the intact knee and ACL kinetics. To account for the remaining motion measurement and recreation errors, an envelope of forces and moments should be reported. These force and moment ranges will provide valuable functional tissue engineering parameters (FTEPs) that can be used to design more effective ACL treatments.

ACL tear

Anterior cruciate ligament (ACL) reconstruction has evolved considerably over the past 30 years. This has largely been due to a better understanding of ACL anatomy and in particular a precise description of the femoral and tibial insertions of its two bundles. In the 1980s, the gold standard was anteromedial bundle reconstruction using the middle third of the patellar ligament. Insufficient control of rotational laxity led to the development of double bundle ACL reconstruction. This concept, combined with a growing interest in preservation of the ACL remnant, led in turn to selective reconstruction in partial tears, and more recently to biological reconstruction with ACL remnant conservation. Current ACL reconstruction techniques are not uniform, depending on precise analysis of the type of lesion and the aspect of the ACL remnant in the intercondylar notch.

Application of a computerised navigation technique to assist arthroscopic anterior cruciate ligament reconstruction

PURPOSE

Based on biomechanical cadaver studies, anatomical double-bundle reconstruction of the anterior cruciate ligament (ACL) was introduced to achieve better stability in the knee, particularly in respect of rotatory loads. Previously, the success of ACL reconstruction was believed to be mainly dependent on correct positioning of the graft, irrespective of the number of bundles for which computer-assisted surgery was developed to avoid malpositioning of the tunnel. The aim of this study was to compare rotational and translational stability after computer-navigated standard single-bundle and anatomical double-bundle ACL reconstruction.

METHODS

The authors investigated 42 consecutive patients who had undergone the single-bundle or double-bundle ACL reconstruction procedure using autogenous hamstring tendon grafts and ENDOBUTTON fixation in patients who had been followed up for a minimum of 24 months. Post-operative anteroposterior and rotational laxity was measured with the KT3000 and compared between groups.

RESULTS

Both surgical procedures significantly improve rotational and translational stability compared to the preoperative ACL-deficient knee (P<0.05). No significant differences were registered between groups with regard to anteroposterior displacement of the tibia. The International Knee Documentation Committee (IKDC) and Lysholm scores were significantly higher in the double-bundle group. However, the results were excellent in both groups.

CONCLUSIONS

The use of computer-assisted ACL reconstruction, which is a highly accurate method of graft placement, could be useful for inexperienced surgeons to avoid malposition. Long-term results of at least five years are needed to determine whether double-bundle ACL reconstruction, which was associated with improved rotational laxity and significantly better IKDC and Lysholm scores compared to the standard single-bundle ACL reconstruction procedure, exerts an influence in terms of avoiding osteoarthritis or meniscus degeneration.

Innovative technology for knee laxity evaluation: clinical applicability and reliability of inertial sensors for quantitative analysis of the pivot-shift test

There has been an increased interest in the quantification of the knee laxity secondary to anterior cruciate ligament (ACL) injury. In clinical practice, the diagnosis is performed by clinical examination and magnetic resonance imaging analysis and confirmed arthroscopically. The pivot shift phenomenon has been identified as one of the essential signs of functional ACL insufficiency. A reliable system to adequately assess patients with ACL injury, quantifying the pivot shift test outcome, is needed. Several studies have been conducted in this regard but the proposed methods remain confined to a research area. The goal of this article is to summarize the actual knowledge and current concepts.

Knee rotational laxity: an investigation of bilateral asymmetry for comparison with the contralateral uninjured knee

BACKGROUND

Instability associated with anterior cruciate ligament injury is commonly evaluated against the patient's contralateral knee. The objectives of this study were, therefore, to assess symmetry of rotational knee laxity in vivo under passive torsional loading in uninjured subjects, and to compare mean rotation of this control group with the contralateral, intact knees of anterior cruciate ligament deficient patients.

METHODS

Axial knee rotation was measured in 29 patients with unilateral anterior cruciate ligament injury and 15 uninjured age and gender-matched control subjects using an imaging-compatible torsional loading device. Side-to-side differences in internal, external, and range of knee rotation were assessed in the control group and mean bilateral knee rotation was compared to the patients' contralateral knee data at both full extension and 30° of flexion.

FINDINGS

Statistically significant differences in symmetry were found in three of the six measures of transverse plane rotation in the uninjured knees; a mean side-to-side difference of 2.2° in range of rotation was detected in the flexed position. No significant differences were observed between the mean values of the healthy control group and the contralateral knees of the anterior cruciate ligament deficient patients.

INTERPRETATION

Bilateral asymmetry of rotational laxity occurs in healthy individuals. Nevertheless, comparability of rotational knee laxity between the contralateral limbs of patients and the uninjured population was evidence that rotational laxity was not inherent or developed in the contralateral knees of the anterior cruciate ligament deficient participants.