Comparison of single- and double-bundle anterior cruciate ligament reconstructions in restoration of knee kinematics and anterior cruciate ligament forces

Relooking at double-bundle versus single-bundle anterior cruciate ligament reconstruction: A biomechanical model to evaluate which can confer better rotatory stability

BACKGROUND

To treat anterior cruciate ligament (ACL) injuries, double-bundle ACL reconstruction has been proposed as a more anatomical approach relative to single-bundle reconstruction. However, controversy remains over which technique is superior in addressing knee instability, particularly rotational laxity. We hypothesize that double-bundle reconstruction better restores rotational knee laxity, while both methods are similar in restoring anterior knee laxity, to intact knee levels.

METHODS

A controlled laboratory study. Eight cadaveric knees were tested accordingly: (1) static anterior laxity testing under 150 N-anterior tibial loading at 20°, 60° and 90° knee flexion using a material testing machine, followed by (2) dynamic simulated pivot-shift with knee-specific loading involving iliotibial band forces, valgus and internal rotation torques, while the knee was brought from extension to 90° flexion on a 6°-of-freedom custom-designed rig. Tibiofemoral kinematics were recorded using an electromagnetic tracking system for the ACL-intact, ACL-deficient, single-bundle and double-bundle ACL-reconstructed knee conditions.

FINDINGS

Double-bundle reconstruction reduced internal rotation under pivot-shift to levels not significantly different from ACL-intact conditions (P > .173), unlike single-bundle that remained significantly higher at 10-40° flexion (P < .05). For anterior laxity, there was no significant difference between double-bundle, single-bundle, and ACL-intact conditions under static testing (P > .175) or pivot-shift (P = .219). The maximum extent of knee envelope laxity was significantly reduced for double-bundle relative to single-bundle, particularly for the rotatory component (P = .012).

INTERPRETATION

Double-bundle was biomechanically superior to single-bundle in addressing envelope of rotation, while both techniques restored anterior knee laxity to ACL-intact levels.

A Comparison of Central Anatomic Single-Bundle Reconstruction and Anatomic Double-Bundle Reconstruction in Anteroposterior and Rotational Knee Stability: Intraoperative Biomechanical Evaluation

Postoperative anterior and rotational stability are still controversial when compared with single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. This study aimed to compare the central anatomical SB and anatomical DB ACL reconstruction in intraoperative knee kinematics during continuous knee flexion-extension. A total of 34 patients who underwent ACL reconstruction using the hamstring tendon were evaluated intraoperatively before and immediately after ACL reconstruction using OrthoPilot ACL Navigation System Version 3.0. The patients were prospectively randomized into the central anatomical SB (17 knees) and the anatomical DB reconstruction (17 knees) groups. The tibial translation and rotation were continuously measured during knee flexion-extension under conventional knee motion, anterior tibial load (100N), and internal-external torque (3 N·m). The anterior tibial translation and total range of tibial rotation were calculated from the measurement values from 20 to 50 degrees at each 5-degree point. The anterior tibial translation (p = 0.59; two-factor repeated measures analysis of variance; η ²G = 0.0077) and total range of tibial rotation (p = 0.95; η ²G = 0.0001) at each knee flexion angle showed no significant difference between the central anatomical SB and anatomical DB reconstruction groups. It is suggested that the central anatomical SB reconstruction is comparable with the anatomical DB reconstruction in biomechanical anteroposterior and rotational knee stability at time 0.

Editorial Commentary: Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Makes More Sense Than Triple-Bundle: Three's a Crowd

Recent research reports impressive patient-reported and objective stability outcomes after triple-bundle anterior cruciate ligament (ACL) reconstruction with hamstring autograft. However, the results are similar to those reported in the orthopaedic literature for single-bundle ACL reconstruction. If the triple-bundle technique does not reduce graft failure rates, and bearing in mind that it is more complex, more expensive, and more difficult to revise, then an anatomically-positioned single-bundle ACL reconstruction makes more sense. If the data supporting double-bundle ACL reconstruction is inconclusive, then why add a third bundle?

Clinical and Radiological Outcomes of Anteromedial Portal Versus Transtibial Technique in ACL Reconstruction: A Systematic Review

Background:

The drilling technique used to make a femoral tunnel is critically important for determining outcomes after anterior cruciate ligament (ACL) reconstruction. The 2 most common methods are the transtibial (TT) and anteromedial (AM) techniques.

Purpose:

To determine whether graft orientation and placement affect clinical outcomes by comparing clinical and radiological outcomes after single-bundle ACL reconstruction with the AM versus TT technique.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Articles in PubMed, EMBASE, the Cochrane Library, ISI Web of Science, Scopus, and MEDLINE were searched from inception until April 25, 2020, using the following Boolean operators: transtibial OR trans-tibial AND (anteromedial OR trans-portal OR independent OR three portal OR accessory portal) AND anterior cruciate ligament.

Results:

Of 1270 studies retrieved, 39 studies involving 11,207 patients were included. Of these studies, 14 were clinical, 13 were radiological, and 12 were mixed. Results suggested that compared with the TT technique, the AM technique led to significantly improved anteroposterior and rotational knee stability, International Knee Documentation Committee (IKDC) scores, and recovery time from surgery. A higher proportion of negative Lachman (P = .0005) and pivot-shift test (P = .0001) results, lower KT-1000 arthrometer maximum manual displacement (P = .00001), higher Lysholm score (P = .001), a higher incidence of IKDC grade A/B (P = .05), and better visual analog scale score for satisfaction (P = .00001) were observed with the AM technique compared with the TT technique. The AM drilling technique demonstrated a significantly shorter tunnel length (P = .00001). Significant differences were seen between the femoral and tibial graft angles in both techniques. Low overall complication and revision rates were observed for ACL reconstruction with the AM drilling technique, similar to the TT drilling technique.

Conclusion:

In single-bundle ACL reconstruction, the AM drilling technique was superior to the TT drilling technique based on physical examination, scoring systems, and radiographic results. The AM portal technique provided a more reproducible anatomic graft placement compared with the TT technique.

Biomechanical comparison of single-bundle versus double-bundle anterior cruciate ligament reconstruction: a meta-analysis

BACKGROUND

Of the many issues regarding surgical techniques related to anterior cruciate ligament reconstruction (ACLR), single-bundle (SB) or double-bundle (DB) ACLR is one of the most debated topics. However, it is unclear which of the techniques yields better outcomes after ACLR for ACL injury. The purpose of this meta-analysis was to compare the benefits of SB versus DB ACLR in terms of biomechanical outcomes.

METHODS

The electronic databases MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and Scopus were searched for relevant articles comparing the outcomes of SB-ACLR versus DB-ACLR that were published until November 2019.

RESULTS

Seventeen biomechanical studies were included. The anterior laxity measured using the anterior drawer test showed significantly better results in DB-ACLR when compared with SB-ACLR. In addition, outcomes of the anterior tibial translation test under a simulated pivot shift presented with better results at low flexion and 30° in DB-ACLR, compared with SB-ACLR. However, there were no significant biomechanical differences between the groups in internal rotation.

CONCLUSIONS

The present study demonstrated that both techniques for ACLR are associated with restoration of normal knee kinematics. DB-ACLR is superior to SB-ACLR in terms of restoration of anteroposterior stability. However, which technique yields better improvement in internal rotation laxity, and internal rotation laxity under a simulated pivot shift at a specific angle, remains unclear.

LEVEL OF EVIDENCE

This is a level II meta-analysis.

Anteromedial Portal Double-Bundle Anterior Cruciate Ligament Reconstruction Yields Similar Outcomes to Non-AMP Femoral Drilling Double-Bundle Techniques: A Systematic Review of Comparative Studies

Background

Biomechanical studies have shown double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) to have increased anterior and rotational stability as compared with single-bundle ACLR. Various techniques exist to drill the femoral tunnel, such as anteromedial portal (AMP), outside-in (OI), and transtibial (TT) drilling. However, it is unclear whether one drilling technique is superior to others when a DB graft is used.

Purpose

To systematically assess the outcomes and complications in patients undergoing DB ACLR through an AMP technique as compared with other femoral drilling techniques.

Study Design

Systematic review; Level of evidence, 3.

Methods

PubMed, Medline, and EMBASE databases were searched in April 2018. Nonrandomized studies were assessed with the MINORS (Methodological Index for Nonrandomized Studies), whereas randomized studies were assessed with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.

Results

Ten studies comprising 722 patients satisfied the inclusion criteria. A total of 351 patients underwent DB ACLR with AMP drilling (mean ± SD age, 32.7 ± 4.7 years); 318 patients had DB ACLR with OI drilling (age, 31.9 ± 4.1 years); and 53 received a DB ACLR with TT drilling (age, 26.5 ± 2.0 years). Graft types used included hamstring autograft (74.1%; n = 247), tibialis anterior autograft (6.0%; n = 20) and unspecified grafts (19.8%; n = 66). No significant difference in postoperative Tegner and Lysholm scores was found between the AMP and OI groups postoperatively. The AMP group had a lower anterior and posterior graft bending angle as compared with the OI group. Four patients (1.1%) in the AMP group had graft reruptures, as compared with 9 reruptures (2.8%) in the OI group. There were no reports of rerupture in the TT group.

Conclusion

DB AMP ACLR results in significantly improved functional outcome scores postoperatively. AMP techniques yield similar functional outcomes to OI ACLR. No direct comparison in functional outcomes scores were available between the AMP and TT techniques. Low overall complication and revision rates were observed for patients undergoing DB AMP ACLR and were found to be similar to those of other femoral drilling techniques. Owing to a steeper graft bending angle in patients undergoing OI or TT ACLR relative to AMP ACLR, patients treated with OI or TT femoral drilling may have increased strain placed on the graft. Based on the various limitations in the available literature, it is not currently possible to make a definite conclusion of whether AMP is superior to non-AMP techniques in the setting of DB ACLR.

External loads associated with anterior cruciate ligament injuries increase the correlation between tibial slope and ligament strain during in vitro simulations of in vivo landings

BACKGROUND

The aim of the present study was to evaluate the relationship between tibial slope angle and ligament strain during in vitro landing simulations that induce ACL failure through the application of variable external loading at the knee. The hypothesis tested was that steeper posterior tibial slope angle would be associated with higher ACL strain during a simulated landing task across all external loading conditions.

METHODS

Kinetics previously derived from an in vivo cohort performing drop landings were reproduced on 45 cadaveric knees via the mechanical impact simulator. MRIs were taken of each specimen and used to calculate medial compartment posterior tibial slope, lateral compartment posterior tibial slope, and coronal plane tibial slope. Linear regression analyses were performed between these angles and ACL strain to determine whether tibial slope was a predictive factor for ACL strain.

FINDINGS

Medial and lateral posterior tibial slope were predictive factors for ACL strain during some landings with higher combined loads. Medial posterior slope was more predictive of ACL strain in most landings for male specimens, while lateral posterior and coronal slope were more predictive in female specimens, but primarily when high abduction moments were applied.

INTERPRETATION

Tibial slope has the potential to influence ACL strain during landing, especially when large abduction moments are present at the knee. Deleterious external loads to the ACL increase the correlation between tibial slope and ACL strain, which indicates that tibial slope angles are an additive factor for athletes apt to generate large out-of-plane knee moments during landing tasks.

Single-bundle versus double-bundle autologous anterior cruciate ligament reconstruction: a meta-analysis of randomized controlled trials at 5-year minimum follow-up

BACKGROUND

Both single-bundle (SB) and double-bundle (DB) techniques were widely used in anterior cruciate ligament (ACL) reconstruction recently. Nevertheless, up to now, no consensus has been reached on whether the DB technique was superior to the SB technique. Moreover, follow-up of the included studies in the published meta-analyses is mostly short term. Our study aims to compare the mid- to long-term outcome of SB and DB ACL reconstruction concerning knee stability, clinical function, graft failure rate, and osteoarthritis (OA) changes.

METHODS

This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed, Embase, and the Cochrane Library were searched from inception to October 2017. The study included only a randomized controlled trial (RCT) that compared SB and DB ACL reconstruction and that had a minimum of 5-year follow-up. The Cochrane Collaboration's risk of bias tool was used to assess the risk of bias for all included studies. Stata/SE 12.0 was used to perform a meta-analysis of the clinical outcome.

RESULTS

Five RCTs were included, with a total of 294 patients: 150 patients and 144 patients in the DB group and the SB group, respectively. Assessing knee stability, there was no statistical difference in side-to-side difference and negative rate of the pivot-shift test. Considering functional outcome, no significant difference was found in proportion with International Knee Documentation Committee (IKDC) grade A, IKDC score, Lysholm scores, and Tegner scores. As for graft failure rate and OA changes, no significant difference was found between the DB group and the SB group.

CONCLUSION

The DB technique was not superior to the SB technique in autologous ACL reconstruction regarding knee stability, clinical function, graft failure rate, and OA changes with a mid- to long-term follow-up.

An animal model of reconstruction of single femoral tunnel with single bone bi-quadruple ACL and internal fixation

We introduced several variables in an animal model of anterior cruciate ligament (ACL) reconstruction to determine the best parameters for surgery in humans. We divided 130 LYD pigs into two groups depending on whether the femoral tunnel goes through the medial tibial tunnel or through the medial fossa of the knee joint. Each subgroup was further divided. Four weeks after surgery the knee specimens were examined for passive flexion and extension test. No group showed a creep effect. In the biomechanical tests, we recorded maximal strength, maximum load, and stiffness parameters. The 100° + 1.0 mm, 1.5 mm, and 2.0 mm positions of the tibial tunnel group, and 10.5 (1.5) + 1.0 mm, 1.5 mm, and 2.0 mm positions of the knee joint cavity group had better biomechanical effects, histocompatibility and revascularization in ACL reconstruction. Overall, these results demonstrated significant differences in the effectiveness of ACL reconstruction based on several surgical parameters, which should contribute to establishing a gold standard for ACL surgery in patients.

A Novel Graft Fixation Technique for Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Grafts

This study evaluated the biomechanical efficacy of single-tunnel double-bundle anterior cruciate ligament (ACL) reconstruction technique. The graft construct is achieved using a novel fixation device that splits an ACL (SPACL) graft into two bundles, recreating the anteromedial (AM) and posterolateral (PL) bundles for ACL reconstruction. A pullout strength test of the SPACL was performed using a 7-mm bovine digital extensor tendon graft. The capability in restoration of knee kinematics after SPACL reconstruction was investigated using cadaveric human knees on a robotic testing system under an anterior tibial load of 134 N and a simulated quadriceps load of 400 N. The data indicated that the SPACL graft has a pullout strength of 823.7±172.3 N. Under the 134 N anterior tibial load, the anteroposterior joint laxity had increased constraint using the SPACL reconstruction but not significantly (p > 0.05) at all selected flexion angles. Under the 400 N quadriceps load, no significant differences were observed between the anterior tibial translation of intact knee and SPACL conditions at all selected flexion angles, but the SPACL graft induced a significant increase in external tibial rotation compared to the intact knee condition at all selected flexion angles with a maximal external rotation of −3.20 deg ±3.6 deg at 90 deg flexion. These data showed that the SPACL technique is equivalent or superior to existing ACL reconstruction techniques in restoration of knee laxity and kinematics. The new SPACL reconstruction technique could provide a valuable alternation to contemporary ACL reconstruction surgery by more closely recreating native ACL kinematics.

Knee Abduction Affects Greater Magnitude of Change in ACL and MCL Strains Than Matched Internal Tibial Rotation In Vitro

BACKGROUND

Anterior cruciate ligament (ACL) injures incur over USD 2 billion in annual medical costs and prevention has become a topic of interest in biomechanics. However, literature conflicts persist over how knee rotations contribute to ACL strain and ligament injury. To maximize the efficacy of ACL injury prevention, the effects of underlying mechanics need to be better understood.

QUESTIONS/PURPOSES

We applied robotically controlled, in vivo-derived kinematic stimuli to the knee to assess ligament biomechanics in a cadaver model. We asked: (1) Does the application of abduction rotation increase ACL and medial collateral ligament (MCL) strain relative to the normal condition? (2) Does the application of internal tibial rotation impact ACL strain relative to the neutral condition? (3) Does combined abduction and internal tibial rotation increase ligament strain more than either individual contribution?

METHODS

A six-degree-of-freedom robotic manipulator was used to position 17 cadaveric specimens free from knee pathology outside of low-grade osteoarthritis (age, 47 ± 8 years; 13 males, four females) into orientations that mimic initial contact recorded from in vivo male and female drop vertical jump and sidestep cutting activities. Four-degree rotational perturbations were applied in both directions from the neutral alignment position (creating an 8° range) for each frontal, transverse, and combined planes while ACL and MCL strains were continuously recorded with DVRT strain gauges implanted directly on each ligament. Analysis of variance models with least significant difference post hoc analysis were used to assess differences in ligament strain and joint loading between sex, ligament condition, or motion task and rotation type.

RESULTS

For the female drop vertical jump simulation in the intact knee, isolated abduction and combined abduction/internal rotational stimuli produced the greatest change in strain from the neutral position as compared with all other stimuli within the ACL (1.5% ± 1.0%, p ≤ 0.035; 1.8% ± 1.3%, p ≤ 0.005) and MCL (1.8% ± 1.0%, p < 0.001; 1.6% ± 1.3%, p < 0.001) compared with all other applied stimuli. There were no differences in mean peak ACL strain between any rotational stimuli (largest mean difference = 2.0%; 95% confidence interval [CI], -0.9% to 5.0%; p = 0.070). These trends were consistent for all four simulated tasks. Peak ACL strain in the intact knee was larger than peak MCL strain for all applied rotational stimuli in the drop vertical jump simulations (smallest mean difference = 2.1%; 95% CI, -0.4% to 4.5%; p = 0.047).

CONCLUSIONS

Kinematically constrained cadaveric knee models using peak strain as an outcome variable require greater than 4° rotational perturbations to elicit changes in intraarticular ligaments.

CLINICAL RELEVANCE

Because combined rotations and isolated abduction produced greater change in strain relative to the neutral position for the ACL and MCL than any other rotational stimuli in this cadaver study, hypotheses for in vivo investigations aimed toward injury prevention that focuses on the reduction of frontal plane knee motion should be considered. Furthermore, reduced strain in the MCL versus the ACL may help explain why only 30% of ACL ruptures exhibit concomitant MCL injuries.

Functional Brace in ACL Surgery: Force Quantification in an In Vivo Study

Background:

A need exists for a functional anterior cruciate ligament (ACL) brace that dynamically supports the knee joint to match the angle-dependent forces of a native ACL, especially in the early postoperative period.

Purpose/Hypothesis:

The purpose of this study was to quantify the posteriorly directed external forces applied to the anterior proximal tibia by both a static and a dynamic force ACL brace. The proximal strap forces applied by the static force brace were hypothesized to remain relatively constant regardless of knee flexion angle compared with those of the dynamic force brace.

Study Design:

Controlled laboratory study.

Methods:

Seven healthy adult males (mean age, 27.4 ± 3.4 years; mean height, 1.8 ± 0.1 m; mean body mass, 84.1 ± 11.3 kg) were fitted with both a static and a dynamic force ACL brace. Participants completed 3 functional activities: unloaded extension, sit-to-stand, and stair ascent. Kinematic data were collected using traditional motion-capture techniques while posteriorly directed forces applied to the anterior aspect of both the proximal and distal tibia were simultaneously collected using a customized pressure-mapping technique.

Results:

The mean posteriorly directed forces applied to the proximal tibia at 30° of flexion by the dynamic force brace during unloaded extension (80.2 N), sit-to-stand (57.5 N), and stair ascent (56.3 N) activities were significantly larger, regardless of force setting, than those applied by the static force brace (10.1 N, 9.5 N, and 11.9 N, respectively; P < .001).

Conclusion:

The dynamic force ACL brace, compared with the static force brace, applied significantly larger posteriorly directed forces to the anterior proximal tibia in extension, where the ACL is known to experience larger in vivo forces. Further studies are required to determine whether the physiological behavior of the brace will reduce anterior knee laxity and improve long-term patient outcomes.

Clinical Relevance:

ACL braces that dynamically restrain the proximal tibia in a manner similar to physiological ACL function may improve pre- and postoperative treatment.

Area of the tibial insertion site of the anterior cruciate ligament as a predictor for graft size

PURPOSE

To determine the distribution of different sizes of the area of the tibial insertion site among the population and to evaluate whether preoperative MRI measurements correlate with intraoperative findings to enable preoperative planning of the required graft size to cover the tibial insertion site sufficiently. The hypothesis was that the area of the tibial insertion site varies among individuals and that there is good agreement between MRI and intraoperative measurements.

METHODS

Intraoperative measurements of the tibial insertion site were taken on 117 patients. Three measurements were taken in each plane building a grid to cover the tibial insertion site as closely as possible. The mean of the three measurements in each plane was used for determination of the area. Two orthopaedic surgeons, who were blinded to the intraoperative measurements, took magnetic resonance imaging (MRI) measurements of the area of the tibial insertion site at two different time points.

RESULTS

The intraoperative measured mean area was 123.8 ± 21.5 mm². The mean area was 132.8 ± 15.7 mm² (rater 1) and 136.7 ± 15.4 mm² (rater 2) when determined using MRI. The size of the area was approximately normally distributed. Inter-rater (0.89; 95 % CI 0.84, 0.92; p < 0.001) and intrarater reliability (rater 1: 0.97; 95 % CI 0.95, 0.98; p < 0.001; rater 2: 0.95; 95 % CI 0.92, 0.96; p < 0.001) demonstrated excellent test-retest reliability. There was good agreement between MRI and intraoperative measurement of tibial insertion site area (ICCs rater 1: 0.80; 95 % CI 0.71, 0.87; p < 0.001; rater 2: 0.87; 95 % CI 0.81, 0.91; p < 0.001).

CONCLUSION

The tibial insertion site varies in size and shape. Preoperative determination of the area using MRI is repeatable and enables planning of graft choice and size to optimally cover the tibial insertion site.

LEVEL OF EVIDENCE

III.

Single-bundle versus double-bundle anterior cruciate ligament reconstruction: A comparative study with propensity score matching

BACKGROUND

Numerous studies have elucidated the functional anatomy and biomechanics of the anterior cruciate ligament (ACL), as a result, double-bundle (DB) ACL reconstruction has received much attention and has become a popular choice because it gives better rotational stability. Many other studies, however, found no differences with respect to stability, and/or other clinical outcomes between the DB and single-bundle (SB) techniques. There is still not enough evidence as to whether the anatomical DB anterior cruciate ligament reconstruction (ACLR) is superior to anatomical SB reconstruction. The purpose of this study is to compare various clinical and functional outcomes between SB and DBACLR at 2 years followup.

MATERIALS AND METHODS

Medical records of patients with ACLR available for at least 2 years followup were reviewed retrospectively. 191 patients (164 males and 25 females) for SB and 48 patients (40 males and 8 females) for DB were selected using the inclusion and exclusion criteria. The mean age of SB and DB was 29.9 and 24.8 years, respectively. Propensity score (PS) was calculated based on age, sex and Tegner activity score and 48 patients in each group were matched by the PS. Lysholm score, International Knee Documentation Committee (IKDC) subjective knee score and Tegneractivity score were investigated. Functional performance tests, isokinetic muscle strength test with Biodex system, pivot shift test and KT-2000 arthrometer test were performed.

RESULTS

At 2 years followup, there were no significant differences between SB and DB group in Lysholm score (92.9 vs. 90.6, P = 0.224), IKDC subjective knee score (88.7 vs. 87.0, P = 0.524), Tegner activity score (7.3 vs. 8.0, P = 0.059). No significant differences were also found in all functional performance tests, isokinetic muscle strength tests in 60° and 180°/s, KT-2000 arthrometer test and pivot shift test (P > 0.05).

CONCLUSIONS

There were no significant differences of clinical and functional outcomes between SB and DB ACLR at 2 years followup.

A new technique in double-bundle anterior cruciate ligament reconstruction with implant-free tibial fixation

PURPOSE

This case-series outcome study presents a surgical technique for anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with 4-tunnel using two interference screws. There was a 2-year minimum follow-up.

METHODS

From January to December 2009, an ACL 4-tunnel, anatomic, double-bundle reconstruction was performed on 27 patients. Double-strand hamstring tendon grafts were used in each femoral tunnel as well as two interference screws. Tibial fixation was insured through manual tension, by tying non-absorbable sutures on the bone bridge between the two tunnels at 20° of knee flexion. Clinical assessments included the International Knee Documentation Committee (IKDC) and Lysholm knee scores, range of motion (ROM), pivot-shift test, single-leg hop, and quadriceps-hamstrings strength tests using a hand-held dynamometer. Anterior knee laxity was also assessed using a rolimeter. A single examiner performed all testing pre-operatively at 6 months and during the 2-year follow-up.

RESULTS

All patients were assessed during the 2-year follow-up. At that time, 92 % of the patients presented normal anterior laxity (average, 1.3 ± 0.5 mm) and rotational knee stability. No statistical side-to-side difference was found for ROM, muscle strength, single-leg hop, and function (n.s.). All patients presented a normal knee function according to the IKDC and the Lysholm score. In addition, no infection, graft failure, or pain were observed at the harvesting site.

CONCLUSION

The study shows that satisfactory results in relation to knee laxity, function, and strength can be achieved with the implant-free tibial fixation in the ACL double-bundle reconstruction with two interference screws.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Anatomic Oblong Double Bundle Anterior Cruciate Ligament Reconstruction

Double-bundle anterior cruciate ligament (ACL) reconstruction using hamstring tendon grafts is a standard procedure for ACL injury. However, its clinical effectiveness is not always satisfactory. One cause of this was problems with the graft-tunnel healing of the posterolateral bundle (PLB) on the femur. To solve this problem, we devised a new anatomic ACL reconstruction technique to improve the graft-tunnel healing of the femoral PLB by using a single-bundle with one bone tunnel on the femoral side and a double-bundle on the tibial side. We have performed 40 procedures with excellent results and no cases of intra- or postoperative complication. This procedure can help improve the graft-tunnel healing around the femoral bone tunnel aperture for the PLB.

Arthroscopic anatomic double bundle anterior cruciate ligament reconstruction: Our experience with follow-up of 4 years

BACKGROUND

Double bundle (DB) anterior cruciate ligament (ACL) reconstruction has been proposed to recreate the natural anatomy of ACL. Reconstruction of the anatomy of both the bundles of ACL has been thought to be able to restore the rotational stability of the knee joint. Nevertheless, it remains unclear whether DB reconstruction has better functional outcome than single bundle (SB) ACL reconstruction.

PURPOSE

To evaluate the clinical outcomes, patient satisfaction and manual laxity tests of knee in patients treated with DB ACL reconstruction in Indian population.

METHODS

We prospectively followed 25 patients with an isolated ACL injury operated for DB ACL reconstruction after applying the inclusion and exclusion criteria. Patients were evaluated pre-operatively and in the post-operative period at regular intervals with the minimum follow up of 4 years. Clinical stability was assessed by anterior drawer test, Lachman test and pivot shift test. Functional outcome was assessed by IKDC, Lysholm and Modified Cincinnati scores.

RESULTS

At the end of 4 years, functional outcome in terms of all subjective scores was satisfactory. Graded stability results of the Lachman, Anterior drawer and pivot shift tests were almost near to that in normal knee. No complication occurred post-operatively.

CONCLUSION

Anatomical DB ACL reconstruction seems to offer satisfactory results in terms of subjective scores and stability tests to patients with ACL tear. It has been found to be associated with no obvious complications and no failures. However a larger patient pool is desired for conclusive results.

Anterior Cruciate Ligament Reconstruction: A 2015 global perspective of the Magellan Society

Background/objective

The Magellan Society is composed of > 150 high-volume fellowship-trained sports surgeons from four continents. These surgeons represent their regional sports organisations in travelling fellowships and are considered to be opinion leaders in their respective organisations. Prior to the 2014 Magellan Meeting in Arima, Japan, a survey was conducted to understand how Magellan members perform anterior cruciate ligament (ACL) reconstruction. This study aims to better understand how ACL reconstruction is performed by sports surgeons worldwide and to determine differences in surgical practice.

Methods

A survey was conducted prior to the Magellan Meeting in Arima, Japan. Information on ACL graft of choice for primary surgery and revision surgery, preferred surgical techniques, and femoral and tibial graft fixation methods was collected. The incidence of meniscal tears and the management of injuries in ACL surgery were also studied. The results of the survey are discussed in this article.

Results

A response rate of 51% (72 member respondents) was achieved for this survey. Hamstring autograft (58%) was the graft of choice for primary ACL reconstruction. The next most common autograft used was bone patella tendon bone autograft (28%). Allograft was the graft of choice in only 4% of respondents. The region of origin of surgeons and the age of surgeons were factors in the ACL graft of choice. Seventy-five percent of surgeons practised single-bundle ACL reconstructions only, 22% performed both single-bundle and double-bundle ACL reconstructions, and 3% performed double-bundle ACL reconstructions exclusively. Sixty-two percent of the respondents drilled femoral tunnels using the anteromedial portal technique. Meniscus repairs were performed in 25% of ACL reconstructions, on average.

Conclusion

Based on the survey, hamstring transportal anatomic single-bundle ACL reconstruction with meniscus preservation is the preferred ACL reconstruction technique of high-volume fellowship-trained sports surgeons.

Comparison of single-bundle versus double-bundle anterior cruciate ligament reconstruction after a minimum of 3-year follow-up: a meta-analysis of randomized controlled trials

Both single-bundle (SB) and double-bundle (DB) procedures have been widely used in the treatment of anterior cruciate ligament (ACL) rupture; however, the optimal repair strategy remains considerably controversial. In this meta-analysis of published studies, we compared the results of these two techniques. After systematic review of electronic databases and websites, a total of 8 RCTs reporting data on 941 subjects were included. The objective and subjective functional recovery outcomes were meta-analyzed. The methodological quality was evaluated using the CBRG scale. The overall pooled data showed superiority in rotational stability, the degree of osteoarthritis (OA) changes, and subjective function score postoperatively in patients managed with DB compared with the SB procedure (pivot shift test, P = 0.02; degree of OA, P = 0.02; Lysholm score, P = 0.04; and Tegner scale, P = 0.002, respectively). However, subgroup analysis suggested no difference between the treatment procedures at long-term follow-up. This meta-analysis demonstrated that the DB technique could result in better rotational stability and higher subjective function score and was effective in preventing OA compared to SB in the mid-term treatment of the injured ACL. Further studies with better design involving larger sample sizes and longer-term follow-up are required.

Biomechanical evaluation of knee kinematics after anatomic single- and anatomic double-bundle ACL reconstructions with medial meniscal repair

PURPOSE

To evaluate knee laxity after anatomic ACL reconstruction with additional suture repair of a medial meniscus tear.

METHODS

Kinematics of the intact knee were determined in 12 human cadaver specimens in response to a 134-N anterior tibial load (aTT) and a combined rotatory load of 10 Nm valgus and 4 Nm internal tibial rotation (aTTPS) using a robotic/universal force moment sensor testing system. Subsequently, the ACL was resected following the creation of a standardized tear of the medial meniscus, a standard meniscus repair and an ACL reconstruction using an anatomic single-bundle (6) or an anatomic double-bundle technique (6). Knee kinematics were determined following every sub-step.

RESULTS

Significant increase of aTT in the ACL-deficient knee was found (p ≤ 0.001) with a further increase in the ACL-deficient knee with additional medial meniscal rupture (p ≤ 0.001). ACL reconstructions significantly decreased aTT compared with the ACL and meniscus-ruptured knee. No significant differences were seen between the intact knee and the ACL-reconstructed knee with additional meniscal repair (p < 0.05). In response to a simulated pivot shift, aTTPS in the intact knee significantly increased in the ACL-deficient knee and meniscus-ruptured knee (p = 0.005). No significant differences in knee kinematics were found between SB as well as DB ACL reconstruction with additional medial meniscal repair compared with the intact knee. Comparison of SB versus DB ACL reconstruction did not reveal any significant differences in a simulated Lachman test or simulated pivot shift test (n.s.).

CONCLUSIONS

aTT as well as aTTPS significantly increased with ACL deficiency compared with the intact knee; additional medial meniscal rupture further increased aTT. Anatomic ACL reconstruction with medial meniscal repair did not reveal significant differences in knee kinematics compared with the intact knee. Comparison of anatomic SB versus DB ACL reconstruction with additional repair of the medial meniscus did not show significant differences neither in a simulated Lachman nor in a simulated pivot shift test.

Kinematic Analysis of Five Different Anterior Cruciate Ligament Reconstruction Techniques

Several anatomical anterior cruciate ligament (ACL) reconstruction techniques have been proposed to restore normal joint kinematics. However, the relative superiorities of these techniques with one another and traditional single-bundle reconstructions are unclear. Kinematic responses of five previously reported reconstruction techniques (single-bundle reconstruction using a bone-patellar tendon-bone graft [SBR-BPTB], single-bundle reconstruction using a hamstring tendon graft [SBR-HST], single-tunnel double-bundle reconstruction using a hamstring tendon graft [STDBR-HST], anatomical single-tunnel reconstruction using a hamstring tendon graft [ASTR-HST], and a double-tunnel double-bundle reconstruction using a hamstring tendon graft [DBR-HST]) were systematically analyzed. The knee kinematics were determined under anterior tibial load (134 N) and simulated quadriceps load (400 N) at 0°, 15°, 30°, 60°, and 90° of flexion using a robotic testing system. Anterior joint stability under anterior tibial load was qualified as normal for ASTR-HST and DBR-HST and nearly normal for SBR-BPTB, SBR-HST, and STDBR-HST as per the International Knee Documentation Committee knee examination form categorization. The analysis of this study also demonstrated that SBR-BPTB, STDBR-HST, ASTR-HST, and DBR-HST restored the anterior joint stability to normal condition while the SBR-HST resulted in a nearly normal anterior joint stability under the action of simulated quadriceps load. The medial-lateral translations were restored to normal level by all the reconstructions. The internal tibial rotations under the simulated muscle load were over-constrained by all the reconstruction techniques, and more so by the DBR-HST. All five ACL reconstruction techniques could provide either normal or nearly normal anterior joint stability; however, the techniques over-constrained internal tibial rotation under the simulated quadriceps load.

Biomechanical evaluation of anatomic single- and double-bundle anterior cruciate ligament reconstruction techniques using the quadriceps tendon

PURPOSE

Quadriceps tendon grafts have renewed interest for ACL reconstruction; however, biomechanical studies comparing anatomic single-bundle (SB) and double-bundle (DB) reconstruction techniques are rare. The purpose of this study was to compare the knee biomechanics in four different types of anatomic ACL reconstruction techniques, using the quadriceps tendon in a human cadaver.

METHODS

Four different tibial (T) and femoral (F) tunnel configurations, (a) DB-2F-2T, (b) DB-2F-1T, (c) SB-1F-1T and (d) DB-1F-2T, were used for ACL reconstruction using the split quadriceps tendon with patella bone. Ten cadaver knees were subjected to an 89 N anterior tibial load and combined 7 N m valgus and 5 N m internal torques. The anterior tibial translation (ATT) and in situ force were measured using a robotic system for the ACL-intact, ACL-deficient and ACL-reconstructed knees.

RESULTS

DB reconstructions mostly restored ATT to the intact ACL. The in situ forces under the anterior load in the DB reconstructions were similar to the intact ACL, but that of the SB reconstruction was different at 30°, 60° and 90° of flexion (P < 0.05). Under combined torques, the in situ force of the SB graft was less than that of intact ACL at 0°, 15° and 30° of knee flexion (P < 0.05), while that of the ACL DB reconstruction was similar to the intact ACL.

CONCLUSION

DB ACL reconstruction using quadriceps tendon can restore biomechanics of the knee to that of the intact ACL regardless of whether three or four tunnels are used, but SB reconstruction does not.

Effect of graft fixation sequence on knee joint biomechanics in double-bundle anterior cruciate ligament reconstruction

PURPOSE

To investigate the effect of graft fixation sequence in double-bundle anterior cruciate ligament (ACL) reconstruction on knee biomechanics.

METHODS

Twelve mature porcine knees underwent double-bundle ACL reconstruction with a randomized fixation order of the two graft bundles. The knees were subjected to external loadings of (1) an 89 N anterior tibial load at 30°, 60° and 90° of knee flexion and (2) 4 N-m internal and external tibial torques at 30° and 60° of knee flexion for ACL intact, deficient and reconstructed states. Knee kinematics and in situ graft forces were measured under the applied loads.

RESULTS

The anterior tibial translation of the two reconstructions was not different from each other but was significantly different from the intact ACL. There was no difference in internal and external rotations between the intact knees and the reconstructions. At lower flexion angles, the graft that was fixed last (whether anteromedial or posterolateral) tended to carry significantly higher in situ load under anterior tibial loading and tibial torques.

CONCLUSION

While a difference in knee kinematics may not be observable with different graft fixation sequences, fixation sequence can alter the in situ forces that the grafts bear under knee loading.

Anteromedial and posterolateral graft kinematics of a double-bundle ACL reconstruction: a 3D computer simulation

BACKGROUND

The posterolateral graft has been reported to fail more frequently than the anteromedial graft in double-bundle ACL reconstructions. This study investigated the graft kinematics using a 3D modelling technique.

METHODS

Twenty subjects performed a stair-ascending activity under dual fluoroscopy surveillance. A double-bundle ACL reconstruction was simulated on those healthy knees using an anteromedial portal technique. The graft-tunnel interaction was described using the graft-tunnel angle and the range of the graft-tunnel edge contact (GTEC).

RESULTS

The femoral graft-tunnel angle of the anteromedial/posterolateral graft was 97.6 ± 7.5/100.7 ± 7.7° and the tibial graft-tunnel angle was 158.8 ± 6.5/146.5 ± 8.9° at knee extension. The femoral GTEC ranges were 23.2 ± 5.3-28.1 ± 7.6° for both grafts and the tibial GTEC ranges were 27.3 ± 2.2-34.5 ± 2.1° during stair-ascending.

CONCLUSION

The femoral graft-tunnel angle was larger than on the tibial side and the GTEC angles influenced the PL graft more, implying that grafts may experience a less optimal biomechanical environment at the femoral tunnels.

Anterior cruciate ligament biomechanics during robotic and mechanical simulations of physiologic and clinical motion tasks: a systematic review and meta-analysis

Investigators use in vitro joint simulations to invasively study the biomechanical behaviors of the anterior cruciate ligament. The aims of these simulations are to replicate physiologic conditions, but multiple mechanisms can be used to drive in vitro motions, which may influence biomechanical outcomes. The objective of this review was to examine, summarize, and compare biomechanical evidence related to anterior cruciate ligament function from in vitro simulations of knee motion. A systematic review was conducted (2004 to 2013) in Scopus, PubMed/Medline, and SPORTDiscus to identify peer-reviewed studies that reported kinematic and kinetic outcomes from in vitro simulations of physiologic or clinical tasks at the knee. Inclusion criteria for relevant studies were articles published in English that reported on whole-ligament anterior cruciate ligament mechanics during the in vitro simulation of physiologic or clinical motions on cadaveric knees that were unaltered outside of the anterior-cruciate-ligament-intact, -deficient, and -reconstructed conditions. A meta-analysis was performed to synthesize biomechanical differences between the anterior-cruciate-ligament-intact and reconstructed conditions. 77 studies met our inclusion/exclusion criteria and were reviewed. Combined joint rotations have the greatest impact on anterior cruciate ligament loads, but the magnitude by which individual kinematic degrees of freedom contribute to ligament loading during in vitro simulations is technique-dependent. Biomechanical data collected in prospective, longitudinal studies corresponds better with robotic-manipulator simulations than mechanical-impact simulations. Robotic simulation indicated that the ability to restore intact anterior cruciate ligament mechanics with anterior cruciate ligament reconstructions was dependent on loading condition and degree of freedom examined.

Prediction of kinematic and kinetic performance in a drop vertical jump with individual anthropometric factors in adolescent female athletes: implications for cadaveric investigations

Anterior cruciate ligament injuries are common, expensive to repair, and often debilitate athletic careers. Robotic manipulators have evaluated knee ligament biomechanics in cadaveric specimens, but face limitations such as accounting for variation in bony geometry between specimens that may influence dynamic motion pathways. This study examined individual anthropometric measures for significant linear relationships with in vivo kinematic and kinetic performance and determined their implications for robotic studies. Anthropometrics and 3D motion during a 31 cm drop vertical jump task were collected in high school female basketball players. Anthropometric measures demonstrated differential statistical significance in linear regression models relative to kinematic variables (p-range <0.01-0.95). However, none of the anthropometric relationships accounted for clinical variance or provided substantive univariate accuracy needed for clinical prediction algorithms (r(2) < 0.20). Mass and BMI demonstrated models that were significant (p < 0.05) and predictive (r(2) > 0.20) relative to peak flexion moment, peak adduction moment, flexion moment range, abduction moment range, and internal rotation moment range. The current findings indicate that anthropometric measures are less associated with kinematics than with kinetics. Relative to the robotic manipulation of cadaveric limbs, the results do not support the need to normalize kinematic rotations relative to specimen dimensions.

ACL double bundle linked cortical-aperture tibial fixation: a technical note

INTRODUCTION

The purpose of this technical note is to describe the tibial fixation characteristics for an all-inside anatomic anterior cruciate ligament (ACL) reconstruction method that links extra-cortical button suspensory and aperture fixation replicating double bundle soft tissue graft function in single femoral and tibial sockets.

MATERIALS AND METHODS

A 55° drill guide aligned guidewires in the ACL footprint center of 8 porcine tibiae (mean apparent bone mineral density = 1.15 g/cm(2)). A Flipcutter created 27 mm sockets and 15 mm guidewire channels. Advancement sutures seated porcine soft tissue graft-PEEK implants to achieve both socket aperture and extra-cortical button suspensory fixation. Potted specimens were loaded into a 6º of freedom clamp with the servohydraulic loading vector in direct socket alignment. Constructs were pre-loaded to 25 N, underwent 10 pre-conditioning cycles (0-50 N, 0.5 Hz), and 500 submaximal loading cycles (50-250 N, 1 Hz) prior to load to failure testing (20 mm/min). Mode of failure was recorded. Descriptive statistical analysis was performed.

RESULTS

All specimens survived the biomechanical test protocol. Displacement during cyclic loading was 2.8 ± 0.9 mm, yield load was 475.2 ± 36 N, ultimate load at failure was 671.4 ± 98 N, stiffness was 127.5 ± 15 N/mm. The most common failure mode was suture pulling through the soft tissue graft.

CONCLUSIONS

This ACL reconstruction method combines the high ultimate load to failure and low graft slippage of extra-cortical button suspensory fixation with the high stiffness of aperture fixation. Biomechanical test findings were comparable or better to previous reports for displacement during submaximal loading, ultimate failure load, and construct stiffness. Based on current understanding of soft tissue graft ACL reconstruction biomechanics, this fixation method should enhance graft-bone socket integration during healing, facilitate long-term graft survival, and improve patient outcomes. Clinical studies are needed to confirm in vivo efficacy.

Functional bracing of ACL injuries: current state and future directions

PURPOSE

Functional braces are commonly prescribed to treat anterior cruciate ligament (ACL) injury. The results of the existing literature on functional brace use are mixed. The purpose of this study was to evaluate the history and current state of functional ACL bracing and to identify design criteria that could improve upon current bracing technologies.

METHODS

A literature search was performed through the PubMed MEDLINE database in April 2013 for the keywords "anterior cruciate ligament" and "brace". Articles published between January 1, 1980, and April 4, 2013, were retrieved and reviewed. Current functional braces used to treat ACL injury were identified. The function of the native ACL was carefully studied to identify design requirements that could improve upon current bracing technologies.

RESULTS

Biomechanical evaluations of functional brace effects at time zero have been mixed. Functional brace use reportedly does not improve long-term patient outcomes following ACL reconstruction, but has been shown to reduce subsequent injury rates while skiing in both ACL-deficient and reconstructed skiers. In situ force in the ACL varies with flexion angle and activity. Currently, no brace has been designed and validated to replicate the force-flexion behavior of the native ACL.

CONCLUSIONS

Biomechanical and clinical evidence suggests current functional bracing technologies do not sufficiently restore normal biomechanics to the ACL-deficient knee, protect the reconstructed ACL, and improve long-term patient outcomes. Further research into a functional brace designed to apply forces to the knee joint similar in magnitude to the native ACL should be pursued.

LEVEL OF EVIDENCE

III.

Biomechanical evaluation of the quadriceps tendon autograft for anterior cruciate ligament reconstruction: a cadaveric study

BACKGROUND

Recently, many surgeons have chosen the quadriceps tendon (QT) as an autograft for anterior cruciate ligament (ACL) reconstruction. However, there have not been biomechanical studies that quantitatively evaluated knee function after reconstruction using a QT autograft.

PURPOSE

To measure the 6 degrees of freedom knee kinematics and in situ graft forces after reconstruction with a QT autograft compared with a quadrupled semitendinosus and gracilis (QSTG) tendon autograft.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten human cadaveric knees (age, 54-64 years) were tested in 3 conditions: (1) intact, (2) ACL deficient, and (3) after ACL reconstruction using a QT or QSTG autograft. With use of a robotic/universal force-moment sensor testing system, knee kinematics and in situ forces in the ACL and autografts were obtained at 5 knee flexion angles under externally applied loads: (1) 134-N anterior tibial load, (2) 134-N anterior tibial load with 200-N axial compression, and (3) 10-N·m valgus and 5-N·m internal tibial torque.

RESULTS

Under the anterior tibial load, both autografts restored anterior tibial translation to within 2.5 mm of the intact knee and in situ forces to within 20 N of the intact ACL at 15°, 30°, and 60°. Adding compression did not change these findings. With the combined rotatory load, the anterior tibial translation and graft in situ forces were again not significantly different from the intact ACL. There were no significant differences between the grafts under any experimental condition.

CONCLUSION

Reconstruction of the ACL with a QT autograft restored knee function to similar levels as that reconstructed with a QSTG autograft under loads simulating clinical examinations.

CLINICAL RELEVANCE

The positive biomechanical results of this cadaveric study lend support to the use of a QT autograft for ACL reconstruction, as it could restore knee function immediately after surgery under applied loads that mimic clinical examinations.

Basic science of anterior cruciate ligament injury and repair

Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. Surgical reconstruction is the current standard of care for treatment of ACL injuries in active patients. The widespread adoption of ACL reconstruction over primary repair was based on early perception of the limited healing capacity of the ACL. Although the majority of ACL reconstruction surgeries successfully restore gross joint stability, post-traumatic osteoarthritis is commonplace following these injuries, even with ACL reconstruction. The development of new techniques to limit the long-term clinical sequelae associated with ACL reconstruction has been the main focus of research over the past decades. The improved knowledge of healing, along with recent advances in tissue engineering and regenerative medicine, has resulted in the discovery of novel biologically augmented ACL-repair techniques that have satisfactory outcomes in preclinical studies. This instructional review provides a summary of the latest advances made in ACL repair. Cite this article: Bone Joint Res 2014;3:20-31.

Progression of osteoarthritis after double- and single-bundle anterior cruciate ligament reconstruction

BACKGROUND

No consensus has been reached on the advantages of double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) over the single-bundle (SB) technique, particularly with respect to the prevention of osteoarthritis (OA) after ACLR.

PURPOSE

To evaluate whether DB ACLR has any advantages in the prevention of OA or provides better stability and function after ACLR compared with the SB technique.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A total of 130 patients with an ACL injury in one knee were prospectively randomized into a DB group (n = 65) or an SB group (n = 65). For the radiologic evaluation, we determined the degree of OA based on the Kellgren-Lawrence grade before the operation and at the time of the final follow-up and determined the number of patients with progression of OA more than one grade from pre- to postoperation. We evaluated the stability results using the Lachman and pivot-shift tests and stress radiography. We also compared the functional outcomes based on the Lysholm knee score, Tegner activity score, and International Knee Documentation Committee (IKDC) subjective scale.

RESULTS

Six patients (4 in the DB group and 2 in the SB group) suffered graft failure during the follow-up and had ACL revision surgery (P = .06). A total of 112 patients were observed for a minimum of 4 years (DB group, n = 52; SB group, n = 60). Five patients (9.6%) in the DB group and 6 patients (10%) in the SB group had more advanced OA at the final follow-up (P = .75). All patients recovered full range of motion within 6 months from surgery. Stability results of the Lachman test, pivot-shift test, and the radiographic stability test failed to reveal any significant intergroup differences (P = .37, .27, and .67, respectively). In the pivot-shift result, the DB group had 4 patients with grade 2 and the SB group had 3 patients with grade 2 (P = .27). Clinical outcomes, including Lysholm knee and Tegner activity scores, were similar in the 2 groups. Statistical significance was achieved only for the IKDC subjective scale (78.2 in DB group vs 73.1 in SB group; P = .03).

CONCLUSION

The DB technique, compared with SB, was not more effective in preventing OA and did not have a more favorable failure rate. Although the DB ACLR technique produced a better IKDC subjective scale result than did the SB ACLR technique, the 2 modalities were similar in terms of clinical outcomes and stability after a minimum 4 years of follow-up.

Biomechanical comparison of anatomic single- and double-bundle anterior cruciate ligament reconstructions: an in vitro study

BACKGROUND

Arthroscopic identification of the anteromedial (AM) and posterolateral (PL) bundle locations of the anterior cruciate ligament (ACL) has facilitated an improved quantitative description of ACL anatomy. Few studies have directly compared the biomechanical laxity of anatomic single-bundle (SB) versus anatomic double-bundle (DB) ACL reconstruction techniques based on precise anatomic descriptions.

HYPOTHESIS

Anatomic tunnel positioning for SB and DB reconstructions would produce comparable anterior-posterior and rotatory knee laxity.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine matched pairs of cadaveric knees were evaluated for the kinematics of intact, ACL-deficient, and either anatomic SB or anatomic DB ACL-reconstructed knees. Reconstruction tunnels were placed either centrally in the ACL footprint or within the AM and PL footprints. A 6 degrees of freedom robotic system was used to assess knee laxity with an 88-N anterior tibial load and a simulated pivot-shift test of combined 10-N · m valgus and 5-N · m internal tibial torques. Rotational motion was measured with internal and external torques of 5 N · m along with varus and valgus torques of 10 N · m. One-sample and 2-sample independent t tests were used to compare between groups (P < .05).

RESULTS

No significant differences were found between anatomic SB and DB reconstruction groups during anterior tibial loading. Anterior tibial translations during simulated pivot shift had no significant differences between anatomic reconstruction groups. Tibial rotation for internal/external and varus/valgus torques showed no significant differences between anatomic reconstructions, with the exception of small (<3°) but statistically significant differences in internal rotation at 20° and 30° of flexion. Despite the similar behavior between the 2 anatomic reconstruction groups, neither technique was able to reproduce the intact state during an anterior tibial load.

CONCLUSION

No significant differences in anterior translation were found between the anatomic SB and anatomic DB ACL reconstructions for simulated pivot shift or anterior tibial loading.

CLINICAL RELEVANCE

Although significant differences between reconstructions were observed for internal rotation, the small magnitude of these differences (<3°) may not have clinical significance.

A novel graft preparation technique of the quadriceps tendon for arthroscopic double-bundle anterior cruciate ligament reconstruction

Surgical reconstruction is a general approach for an anterior cruciate ligament rupture. Techniques have evolved from single-bundle to double-bundle reconstruction to restore the 2 anatomically and functionally different bundles as much as possible. However, there is controversy regarding which method yields superior clinical outcomes. The purpose of this article is to introduce our new graft preparation method, which will potentially address the limitations of currently available double-bundle anterior cruciate ligament reconstruction procedures using the quadriceps tendon. The proximal portion of the graft is preserved in our method, instead of completely being split into 2 distinct graft bundles as previously suggested. We believe that the preserved portion can act as a biofunctional "safety circuit" in case of overloading and also help some synergistic actions of the 2 bundles.

The kinematic analysis of female subjects after double-bundle anterior cruciate ligament reconstruction during single-leg squatting

BACKGROUND

The kinematic characteristics of female anterior cruciate ligament (ACL)-injured subjects were recognized in our previous study using an electromagnetic device comparing both female control groups and male ACL-injured subjects during single-leg squatting.

OBJECTIVE

To assess the kinematic characteristics of female subjects after double-bundle ACL reconstruction during single-leg squatting.

METHODS

Three-dimensional motion analysis was performed for single-leg squatting in female subjects after ACL reconstruction. We evaluated the relative angles between the pelvis, thigh, and lower leg using an electromagnetic device during single-leg squatting in 28 female subjects with ACL reconstruction. All patients included in this study restored their sports performance level to 90 % or higher.

RESULTS

Comparing the involved leg to the uninjured leg of female subjects after ACL reconstruction, the involved leg demonstrated significantly more hip adduction and less knee varus than the uninjured leg. Comparing the anterior cruciate ligament-reconstructed female subjects to the healthy female controls, the involved leg after ACL reconstruction demonstrated significantly less hip flexion, more hip external rotation, more hip adduction, and more knee flexion than the dominant leg of the control group.

CONCLUSION

This kinematic study exhibited kinematic characteristics of ACL-reconstructed knees of female subjects. Double-bundle anterior cruciate ligament reconstruction could not quite restore the normal kinematics of female-involved legs compared with both uninjured legs of female subjects and healthy female controls. In future studies, restoring the correct alignment of ACL reconstructed knee during single-leg squatting would be expected to reduce ACL re-injury and to assist a safe return to sport activities.

There is significant load sharing and physical interaction between the anteromedial and posterolateral bundles of the ovine ACL under anterior tibial loads

INTRODUCTION

The ovine stifle joint is an ideal preclinical model to test the ability of double-bundle reconstruction techniques in providing superior joint stability and less osteoarthritis (OA) compared with single-bundle techniques. However, knowledge of the normal ovine ACL and more specifically the load sharing and physical interaction between the two main bundles of the ovine ACL is currently limited.

METHODS

Six ovine stifle joints were tested using a robotic testing system. Each joint was cyclically loaded to 200N in the anterior tibial direction between 30° and 90° flexion and the force-displacement data were recorded for both the intact ACL, and when the anteromedial (AM, n=3) or the posterolateral bundle (PL, n=3) was transected.

RESULTS

The load shared by the AM bundle increased from 30° to 75° of flexion at all loading levels (25-200N); whereas, the load shared by the PL bundle decreased between full extension and mid flexion (60°) and then increased again. The load borne by the AM bundle did not change in response to increasing Anterior Tibial Loads (ATL) at each flexion angle, in contrast to the PL bundle (P=0.004). Physical interaction between bundles was greatest at 60° and under 50N ATL.

CONCLUSION

These data will help create double-bundle ACL reconstructions in sheep which are functionally similar to intact native ACL. In turn, this model can be used to examine the success of anatomically accurate double-bundle reconstructions to prevent the development of OA.

LEVEL OF EVIDENCE

III.

Failure of anterior cruciate ligament reconstruction

Failure after anterior cruciate ligament reconstruction is a potentially devastating event that affects a predominantly young and active population. This review article provides a comprehensive analysis of the potential causes of failure, including graft failure, loss of motion, extensor mechanism dysfunction, osteoarthritis, and infection. The etiology of graft failure is discussed in detail with a particular emphasis on failure after anatomic anterior cruciate ligament reconstruction.

The accuracy of bone tunnel position using fluoroscopic-based navigation system in anterior cruciate ligament reconstruction

PURPOSE

The first purpose of this study was to examine whether fluoroscopic-based navigation system contributes to the accuracy and reproducibility of the bone tunnel placements in single-bundle anterior cruciate ligament (ACL) reconstruction. The second purpose was to investigate the application of the navigation system for double-bundle ACL reconstruction.

METHODS

A hospital-based case-control study was conducted, including a consecutive series of 55 patients. In 37 patients who received single-bundle ACL reconstruction, surgeries were performed with this system for 19 knees (group 1) and without this system for 18 knees (group 2). The positioning of the femoral and tibial tunnels was evaluated by plain sagittal radiographs. In 18 patients who received double-bundle ACL reconstruction using the navigation system (group 3), the bone tunnel positions were assessed by three-dimensional computed tomography (3D-CT). Clinical assessment of all patients was followed with the use of Lysholm Knees Score and IKDC.

RESULTS

Taking 0% as the anterior and 100% as the posterior extent, the femoral tunnels were 74.9 ± 3.0% in group 1 and 71.5 ± 5.8% in group 2 along Blumensaat's line, and the tibial tunnels were 42.3 ± 1.4% in group 1 and 42.5 ± 4.6% in group 2 along the tibia plateau. The bone tunnel positions in group 1 were located significantly closer to the position planned preoperatively and varied less in both femur and tibial side, compared with those without navigation (group 2). (Femur: P < 0.05, Tibia: P < 0.001) 3D-CT evaluation of double-bundle ACL reconstruction (group 3) also demonstrated that the bone tunnel positions of both anteromedial (AM) and posterolateral (PL) were placed as we expected.

CONCLUSION

The fluoroscopic-based navigation system contributed to the more reproducible placement of the bone tunnel during single-bundle ACL reconstruction compared with conventional technique. Additionally, this device was also useful for double-bundle ACL reconstruction.

LEVEL OF EVIDENCE

Case-control study, Therapeutic study, Level III.

A tale of 10 European centres - 2010 APOSSM travelling fellowship review in ACL surgery

The purpose of ESSKA- APOSSM Travelling fellowship is to better understand the epidemiology, management and surgical techniques for sports across continents. There has been a progressive evolution in ACL reconstruction and there is variation in technique in ACL reconstruction amongst the most experienced surgeons in different continents. During this one month fellowship, we saw various ACL reconstruction techniques using different graft sources, with a variety of graft fixation methods, with the common aim of recreating an anatomical ACL reconstruction.

A matched pairs comparison of single- versus double-bundle anterior cruciate ligament reconstructions, clinical results and manual laxity testing

PURPOSE

To compare the subjective clinical results as well as manual anterior and rotational stability in patients treated with either single- (SB) or double-bundle (DB) anterior cruciate ligament (ACL) reconstructions.

METHODS

Sixty-four patients who had undergone SB or DB hamstring ACL reconstruction with hamstrings were included in a retrospective matched pair analysis. At follow-up IKDC subjective, CKS, KOOS, CKS and a visual analogue satisfaction scale was assessed. A blinded surgeon examined the joint laxity and completed the objective IKDC. The KT-1000 was used to bilaterally test anterior tibial translation. Patients with confounding variables, which statistically influenced the clinical outcome (passive flexion and extension deficits, persistent quadriceps deficit, tibiofemoral osteoarthritis and non-repairable medial meniscus injury), were identified and excluded from the statistical analysis (n = 10).

RESULTS

For all subjective scores, DB patients reported increased scores compared with SB patients. While consistently higher scores were demonstrated, statistical significance was only achieved for the IKDC subjective (P = 0.04) and VAS satisfaction (P = 0.02). Graded stability results of the Lachman, anterior drawer and pivot-shift tests were significantly higher in the DB group and KT-1000 side-to-side difference was significantly better for DB (P = 0.01).

CONCLUSION

DB ACL reconstruction appeared to more consistently result in significantly higher subjective outcome scores and manual tests of joint stability than SB ACL reconstruction. Besides the surgical technique, normal extension and quadriceps strength after surgery were identified to be an essential component in order to provide the patient with a successful outcome.

Relationship between thickness of the anteromedial bundle and thickness of the posterolateral bundle in the normal ACL

PURPOSE

Since the development of the anatomic double-bundle anterior cruciate ligament (ACL) reconstruction, many studies have focused on excursion and/or tension of each graft. However, no studies to date have adequately investigated thickness of the graft in anatomic double-bundle ACL reconstruction. To obtain basic knowledge from which an ideal graft thickness can be inferred, thicknesses of the anteromedial bundle (AMB) and posterolateral bundle (PLB) was measured in the normal ACL.

METHODS

The right knees of 50 cadavers donated for anatomy instruction were studied. Each ACL was separated into the AMB and PLB, and circumferences at the mid-substance and cross-sectional area at the femoral and tibial footprints were measured in each.

RESULTS

Cross-sectional areas of the AMB and PLB were 36 ± 10 and 32.1 ± 10.2 mm² at the femoral footprint, and 60.9 ± 21.8 and 52.2 ± 17.3 mm² at the tibial footprint, respectively. Circumferences at the mid-substance were 14.3 ± 3.3 mm for the ALB and 10.8 ± 3.1 mm for the PLB. A positive correlation was seen between AMB and PLB at each of the three sites.

CONCLUSION

The AMB is thicker than the PLB, showing a constant correlation in the normal ACL. This suggests that the anteromedial graft must be thicker than the posterolateral graft at least in actual operations.

Comparison of the clinical outcome of double-bundle, anteromedial single-bundle, and posterolateral single-bundle anterior cruciate ligament reconstruction using hamstring tendon graft with minimum 2-year follow-up

PURPOSE

The purpose of this study was to obtain more than 2 years' follow-up after surgery to investigate the effect of the difference in rotatory stability based on our previous data on the clinical outcome among 3 groups: double-bundle (DB) reconstruction group, anteromedial (AM) single-bundle reconstruction group, and posterolateral (PL) single-bundle reconstruction group.

METHODS

We randomly separated 55 patients with anterior cruciate ligament rupture into 3 groups: 18 in DB group, 18 in AM group, and 19 in PL group. The mean follow-up period is 33.7 months for the DB group, 31.9 months for the AM group, and 33.2 months for the PL group. We evaluated the Lysholm score, Tegner score, anterior laxity with the KT-1000 arthrometer (MEDmetric, San Diego, CA), rotator instability with the pivot-shift test, and muscle strength with knee extensor and flexor isokinetic peak torques at 60°/s.

RESULTS

There were no significant differences in postoperative Lysholm score and Tegner score. Anterior stability of the knee, as measured by the KT-1000 arthrometer, was significantly better in the DB group than the PL group (P < .05). The negative rate of the manual pivot-shift test in the DB group was significantly superior to the PL group (P < .05). Muscle strength of the extensor in the DB group was significantly superior to that in the AM group (P < .05), and muscle strength of the flexor in the PL group was significantly inferior to that in both the DB and AM groups (P < .05). Two patients in the PL group had rerupture; however, there was no graft failure in the other groups.

CONCLUSIONS

At 2 years' follow-up, patients undergoing DB anterior cruciate ligament reconstruction had greater extension strength than patients receiving an AM single-bundle reconstruction. The DB and AM groups had greater flexion strength than the PL group. The DB and AM groups had a similar rate of negative pivot-shift test results, whereas the PL group had fewer negative pivot-shift test results than the DB group. There were no KT-1000 side-to-side differences between the DB and AM groups, whereas the DB group had better results than the PL group. Overall, the clinical outcome as measured by Lysholm and Tegner scores was not different between groups.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

In vitro and intraoperative laxities after single-bundle and double-bundle anterior cruciate ligament reconstructions

PURPOSE

The purpose of this study was to objectively evaluate whether double-bundle anterior cruciate ligament (ACL) reconstruction can better restore the normal translational and rotational laxities than the conventional single-bundle ACL reconstruction among the reported biomechanical studies.

METHODS

A systematic literature search was conducted to identify in vitro and in vivo (intraoperative) biomechanical studies that compared the laxities (anterior or anteroposterior or rotational) between single- and double-bundle ACL reconstructions. Because of large variability among the loading conditions and testing methods used to determine the rotational laxities among the studies, a meta-analysis of rotational laxities was not feasible.

RESULTS

Seven in vitro and three in vivo studies were included in this analysis based on the predefined inclusion criteria. The overall mean differences calculated by the random effects model in anteroposterior laxity between the single-bundle and double-bundle ACL reconstruction techniques at 0°, 30°, 60°, and 90° of flexion were 0.99 mm, 0.38 mm, 0.34 mm, and 0.07 mm, respectively. No statistically significant difference was noted between the 2 treatments at all flexion angles. Among the 9 studies that compared the rotational laxity of single-bundle and double-bundle ACL reconstructions, 4 reported that double-bundle reconstruction can provide better rotational control than single-bundle reconstruction. The other 5 studies could not identify any significant difference between the 2 reconstructions in terms of rotational laxity.

CONCLUSIONS

Both single- and double-bundle treatment options for ACL injury result in similar anteroposterior knee joint laxity at time 0. No conclusive evidence on the superiority of 1 reconstruction technique over the other in terms of rotation laxity can be obtained because of several variations in the experimental protocol and the kinematics used to measure the rotational laxity among the studies.

LEVEL OF EVIDENCE

Level III, meta-analysis.

The effect of graft fixation sequence on force distribution in double-bundle anterior cruciate ligament reconstruction

PURPOSE

This paper investigated the effect of graft fixation sequence on knee joint biomechanics after a double-bundle ACL reconstruction.

METHOD

Two independently published biomechanical studies that investigated the biomechanics of double-bundle ACL reconstructions using similar robotic testing systems were compared. In each study, ten human cadaveric knees were tested under three different conditions: intact, ACL deficient, and ACL reconstructed using a double-bundle technique with the anteromedial (AM) graft fixed at 60° of flexion and the posterolateral (PL) graft fixed at full extension. In one study (Study A), the AM graft was fixed first; while in another study (Study B), the PL graft was fixed first. Knee kinematics, in situ forces of the ACL and the ACL grafts were measured under two loading conditions: an anterior tibial load of 134 N and a combined tibial torques (10 N·m valgus and 5 N·m internal tibial torques) in both studies.

RESULT

When AM graft was fixed first, the in situ force of the AM graft was lower than the native AM bundle at all flexion angles. The in situ force in the PL graft, however, was higher than the native PL bundle at all flexion angles. When the PL graft was fixed first, the in situ force of the AM graft was higher than the native AM bundle, while the in situ forces of the PL graft were lower than the native PL bundle at all flexion angles. Both studies demonstrated that the double-bundle ACL reconstructions can closely restore the normal knee joint kinematics.

CONCLUSION

Even though the grafts were fixed using similar initial tensions and at same flexion angles, the sequence of fixing the two grafts in a double-bundle ACL reconstruction could alter the in situ forces in the grafts and affect the knee kinematics. These data imply that in clinical application of a double-bundle ACL reconstruction, the sequence of graft fixation should be an important surgical parameter.

Double-bundle ACL reconstruction demonstrated superior clinical stability to single-bundle ACL reconstruction: a matched-pairs analysis of instrumented tests of tibial anterior translation and internal rotation laxity

PURPOSE

To compare objective measures of in vivo joint laxity between patients treated with single-bundle (SB) or double-bundle (DB) anterior cruciate ligament (ACL) reconstructions.

METHODS

Sixty-four patients matched by age, height, weight, and that had undergone unilateral SB or DB hamstring ACL reconstruction participated in this study. Bilateral anterior tibial translation (ATT) was recorded using the KT1000 arthrometer, and a robotic testing system was used to assess side-to-side differences in rotational characteristics. Each reconstruction was evaluated to determine how well it mimicked the anteroposterior (AP) and rotational biomechanics of the normal knee. A reconstruction was defined as mimicking the normal knee if ATT and internal rotation (IR) were within 3 mm and 3.5°, respectively.

RESULTS

Side-to-side differences in ATT were significantly higher for the SB group (2.2 ± 1.4 mm) than the DB group (1.1 ± 1.0 mm, P = 0.001). While relative side-to-side differences in IR did not differ between the SB (1.3°) and DB groups (1.1°, P = 0.82), absolute IR differences were significantly less with the DB reconstruction (2.1° vs. 4.7°, P = 0.001). A significantly greater percentage of DB patients (81%, P = 0.0003) had both ATT and IR similar to the normal knee, compared to 34% of the SB patients; however, IKDC subjective scores did not differ between groups. Regardless of technique, patients with the greatest rotational laxity of their non-operative knee demonstrated significantly worse IKDC scores.

CONCLUSION

DB reconstruction resulted in reduced side-to-side differences in both ATT and IR. The DB technique more consistently reproduced the biomechanical profile of the uninjured limb than did the SB technique without increasing the risk of over-constraining the knee.