Anatomic single- and double-bundle anterior cruciate ligament reconstruction, part 1: Basic science

Anterior cruciate ligament reconstruction is a frequently performed orthopaedic procedure. Although short-term results are generally good, long-term outcomes are less favorable. Thus, there is renewed interest in improving surgical techniques. Recent studies of anterior cruciate ligament anatomy and function have characterized the 2-bundle structure of the native ligament. During non-weightbearing conditions, the anteromedial (AM) and posterolateral (PL) bundles display reciprocal tension patterns. However, during weightbearing, both the AM and PL bundles are maximally elongated at low flexion angles and shorten significantly with increasing knee flexion. Conventional single-bundle reconstruction techniques often result in nonanatomic tunnel placement, with a tibial PL to a femoral "high AM" tunnel position. In vitro studies have demonstrated that these nonanatomic single-bundle reconstructions cannot completely restore normal anterior-posterior or rotatory laxity. Cadaveric studies suggest that anatomic single-bundle and anatomic double-bundle reconstruction may better restore knee stability. Although many cadaver studies suggest that double-bundle reconstruction techniques result in superior stability when compared with single-bundle techniques, others failed to demonstrate a clear benefit of this more complex procedure. Cadaver studies generally do not apply physiologically relevant loads and provide only a "time-zero" assessment that ignores effects of healing and remodeling after anterior cruciate ligament reconstruction. In vivo, dynamic studies offer the most comprehensive assessment of knee function after injury or reconstruction, as they can evaluate dynamic stability during functional joint loading. Studies of knee kinematics during activities such as gait and running suggest that nonanatomic single-bundle anterior cruciate ligament reconstruction fails to restore preinjury knee function under functional loading conditions. Similar studies of more anatomic single- and double-bundle surgical approaches are in progress, and preliminary results suggest that these anatomic techniques may be more effective for restoring preinjury knee function. However, more extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction.     

Anatomical double-bundle anterior cruciate ligament reconstruction

A careful review of the literature suggests that a significant number of patients undergoing anterior cruciate ligament (ACL) reconstruction have less than optimal results. Although overall outcomes of ACL reconstruction are favourable, there remains considerable room for improvement. Anatomically, the ACL consists of two major functional bundles, the anteromedial and the posterolateral bundle. Biomechanically, both bundles contribute significantly to the anterior and the rotational stability of the knee. Therefore, anatomical double-bundle ACL reconstruction techniques may further improve the outcomes in ACL surgery. Our preferred technique for arthroscopic double-bundle ACL reconstruction includes the use of two femoral and two tibial tunnels to restore both the anteromedial and the posterolateral bundle of the ACL and their anatomical footprints at their tibial and femoral insertion site. We use two tibialis anterior tendon allografts for the restoration of the two ACL bundles. Clinical long-term outcome studies may focus on the evaluation of functional outcomes, restoration of anterior and rotational knee stability, and the risk of degenerative osteoarthritis of the knee joint following anatomical double-bundle ACL reconstruction versus single-bundle ACL reconstruction.     

Avoiding pitfalls in anatomic ACL reconstruction

As interest in double-bundle anterior cruciate ligament (ACL) reconstruction grows, we continue to refine our technique to perform the most anatomic reconstruction possible. Our experience has brought to our attention the potential mistakes that should be avoided when performing an anatomic double-bundle ACL reconstruction. These mistakes include (1) failure to visualize the femoral insertion completely, (2) use of the clock face to reference femoral tunnel positioning, (3) nonanatomic tunnel placement leading to graft impingement, (4) mismatching tibial and femoral tunnels, and (5) failure to restore the native tension pattern of the ACL. It is also important to recognize that a double-bundle ACL reconstruction is not necessarily equivalent to an anatomic double-bundle reconstruction. This article reviews potential mistakes in DB ACL reconstruction and describes our way of avoiding them.     

前交叉韧带解剖重建理念与方法

前交叉韧带(Anterior Cruciate Ligament,ACL)解剖重建技术是基于ACL解剖理论发展起来的一项手术技术。ACL解剖重建是根据ACL的解剖特点进行功能重建,恢复ACL原有的尺寸、韧带胶原走行方向和止点位置。解剖重建不仅包括双束和单束重建,而且包括以此理论为基础的ACL重建术后的翻修与加固。本文对ACL的解剖重建技术进行介绍,针对在关节镜下如何观察原ACL的止点位置,测量止点长宽,选择骨道位置,如何利用影像学进行评价进行了详细的阐述和解释,并介绍了该技术目前的临床评价结果。同时,本文对ACL解剖重建和传统"经典"重建方法的区别进行了重点说明与解释,为提高国内医师对ACL解剖重建技术的认识提供参考和帮助。     

Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis

Purpose

To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero–posterior (A–P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction.

Methods

An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I–II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A–P laxity measures using navigation and total internal–external (IRER) laxity measured using navigation, as well as graft failure frequency.

Results

A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95 % CI 0.214–0.513, p < 0.001) and less A–P laxity measured with navigation (SMD = 0.29 95 % CI 0.01–0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction.

Conclusion

Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A–P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain.

Level of evidence

II.     

ACL Reconstruction with Double-Bundle Technique: A Review of Clinical Results

Abstract

Anatomical and biomechanical studies have shown that the anterior cruciate ligament (ACL) primarily consists of 2 distinct bundles, the anteromedial (AM) and posterolateral (PL), which act separately during the knee's range of motion. Conventional ACL reconstruction techniques have focused on restoration of the AM bundle only, while giving limited attention to the PL bundle. The outcomes of these single-bundle techniques have been relatively good in ACL reconstruction. In recent years, many authors have developed double-bundle ACL reconstruction techniques to better replicate ACL anatomy and its 2 bundles. The purpose of this article is to analyze the clinical results of the double-bundle ACL reconstruction according to the current literature. The review focuses primarily on randomized controlled trials. According to the 14 randomized controlled trials published in the literature and included in this review, 4 (29%) trials did not find any significant differences in the results between double-bundle and single-bundle ACL reconstruction. Ten (71%) trials reported significantly better results with double-bundle technique than with single-bundle technique, of which 7 (50%) reported better rotational stability, 6 (43%) reported better anterior stability, 3 (21%) reported better objective knee scores, 3 (21%) reported better subjective knee scores, 2 (14%) reported fewer graft failures, and 1 (7%) reported less degenerative changes of the knee. In addition, none of the trials found the single-bundle technique to have better results in any of these evaluations when compared with the double-bundle technique. However, 13 (93%) of the 14 trials had only a short-term follow-up (1–3 years), and only 1 (7%) trial conducted long-term follow-up (8–10 years). Therefore, only through long-term follow-up studies will we be able to determine whether the double-bundle reconstruction is really better than the single-bundle technique.     

Dynamic knee laxity measurement devices

Purpose  

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

Stability evaluation of single-bundle and double-bundle reconstruction during navigated ACL reconstruction

Recently, anatomic double-bundle anterior cruciate ligament (ACL) reconstructions, which reproduce the anteromedial and posterolateral bundles, have been developed to improve knee laxity. However, there are little data on the in vivo biomechanics after such reconstructions. In this paper, we will review biomechanical and clinical studies that have compared single-bundle and double-bundle reconstruction, and introduce our intraoperative evaluation of double-bundle reconstruction using a navigation system. In the navigation evaluation, knee kinematics before and after ACL reconstruction were assessed, and functions of the anteromedial and posterolateral bundles were evaluated. Although the posterolateral bundle has an important role in the knee extension position, the anteromedial bundle improved knee laxity during the more knee flexion positions. Furthermore, double-bundle reconstruction improved knee laxity compared with either posterolateral or anteromedial bundle reconstruction throughout knee range of motion. Although traditional single-bundle reconstruction, reproducing the anteromedial bundle, is a reasonable procedure, double-bundle reconstruction has the potential to improve knee stability after ACL reconstruction.     

The anatomic approach to primary, revision and augmentation anterior cruciate ligament reconstruction

The anatomic approach is gaining popularity in anterior cruciate ligament (ACL) reconstruction. It is predominantly applied during primary ACL reconstruction. However, following the same principles as during primary surgery, the anatomic approach can also be applied during revision and augmentation surgery. This paper discusses the surgical technique for anatomic single- and double-bundle ACL reconstruction, for primary, revision and augmentation surgery. During primary reconstruction, the choice for single- or double-bundle reconstruction and graft size should be based on ACL insertion site and femoral intercondylar notch dimensions. When there is an isolated anteromedial (AM) or posterolateral (PL) bundle rupture, augmentation of a single-bundle can be performed while protecting the integrity of the intact bundle. Especially during revision surgery, there are many potential situations the surgeon may encounter when entering the knee. There are multiple possible solutions for all of these different situations leading to an anatomic end result. Three-dimensional computed tomography (CT) scanning should be used to evaluate the current tunnel positions and determine the operative strategy.     

Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a prospective,randomize clinical study

Anatomical observation and biomechanical studies have shown that the anterior cruciate ligament (ACL) mainly consists of two distinct bundles, the anteromedial (AM) bundle and posterolateral (PL) bundle. Conventional single-bundle ACL reconstruction techniques have focused on the restoration of the AM bundle while giving limited attention to the PL bundle. The purpose of this prospective, randomized clinical study is to compare the outcomes of ACL reconstruction when using either double-bundle or single-bundle technique and bioabsorbable interference screw fixation, and similar rehabilitation with both techniques. Sixty-five patients were randomized into either double-bundle (n = 35) or single-bundle (n = 30) ACL reconstruction with hamstring tendons and bioabsorbable screw (Hexalon, Inion Company, Tampere, Finland) fixation in both groups. The evaluation methods were clinical examination, KT-1000 arthrometer measurements, radiographic evaluation, as well as International Knee Documentation Committee and Lysholm knee scores. There were no differences between the study groups preoperatively. For an average of 14 months of follow-up (range 12–20 months), 30 patients of the double-bundle group and 29 patients of the single-bundle group were available (91%). At the follow-up, the rotational stability, as evaluated by pivot shift test, was significantly better in the double-bundle group than in the single-bundle group. However, in anterior stability of the knee, there was no significant difference between the groups. None of the patients in the double-bundle group had graft failure, while four patients in the single-bundle group had. In addition, knee scores were equal at the follow-up, and all the results were significantly better at the follow-up than preoperatively, in both groups.     

ACL reconstruction with double-bundle technique: a review of clinical results

Anatomical and biomechanical studies have shown that the anterior cruciate ligament (ACL) primarily consists of 2 distinct bundles, the anteromedial (AM) and posterolateral (PL), which act separately during the knee's range of motion. Conventional ACL reconstruction techniques have focused on restoration of the AM bundle only, while giving limited attention to the PL bundle. The outcomes of these single-bundle techniques have been relatively good in ACL reconstruction. In recent years, many authors have developed double-bundle ACL reconstruction techniques to better replicate ACL anatomy and its 2 bundles. The purpose of this article is to analyze the clinical results of the double-bundle ACL reconstruction according to the current literature. The review focuses primarily on randomized controlled trials. According to the 14 randomized controlled trials published in the literature and included in this review, 4 (29%) trials did not find any significant differences in the results between double-bundle and single-bundle ACL reconstruction. Ten (71%) trials reported significantly better results with double-bundle technique than with single-bundle technique, of which 7 (50%) reported better rotational stability, 6 (43%) reported better anterior stability, 3 (21%) reported better objective knee scores, 3 (21%) reported better subjective knee scores, 2 (14%) reported fewer graft failures, and 1 (7%) reported less degenerative changes of the knee. In addition, none of the trials found the single-bundle technique to have better results in any of these evaluations when compared with the double-bundle technique. However, 13 (93%) of the 14 trials had only a short-term follow-up (1-3 years), and only 1 (7%) trial conducted long-term follow-up (8-10 years). Therefore, only through long-term follow-up studies will we be able to determine whether the double-bundle reconstruction is really better than the single-bundle technique.     

Rotational and translational laxity after computer-navigated single- and double-bundle anterior cruciate ligament reconstruction

Based on biomechanical cadaver studies, anatomic 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 reconstructed bundles for which computer-assisted surgery was developed to avoid malpositioning of the tunnel. The aim of the present study is to compare rotational and translational stability after computer-navigated standard single-bundle, and anatomic double-bundle ACL reconstruction. The authors investigated 55 consecutive patients who had undergone the single-bundle or double-bundle ACL reconstruction procedure with the use of autogenous hamstring tendon grafts and EndoButton^® fixation, and the patients had been followed for a minimum period of 24 months. Intraoperative, anteroposterior and rotational laxity was measured with the computer navigation system, and compared between groups. Both surgical procedures significantly reduced anteroposterior displacement (AP) and internal rotation (IR) of the tibia compared to the pre-operative ACL-deficient knee (P < 0.05). No significant differences were registered between groups with regard to anteroposterior displacement of the tibia. A significantly greater reduction in internal rotation was noted in the double-bundle group (15.6°) compared to the single-bundle group (7.1°). The IKDC and Lysholm score were significantly higher in the double-bundle group. However, the results were excellent in both groups. The use of a computer-assisted ACL reconstruction, which is a highly accurate method of graft placement, could be useful for inexperienced surgeons to avoid malposition. 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, provide an influence in terms of avoiding osteoarthritis or meniscus degeneration, long-term results of at least 5 years are needed.     

Prospective randomized comparison of anatomic single- and double-bundle anterior cruciate ligament reconstruction

Purpose

To determine if anatomic double-bundle anterior cruciate ligament (ACL) reconstruction is superior to anatomic single-bundle reconstruction in restoring the stabilities and functions of the knee joint.

Methods

A prospective randomized clinical study was done to compare the results of 32 cases of anatomic single-bundle ACL reconstruction and 34 cases of anatomic double-bundle ACL reconstruction with average follow-up of 16.3 ± 3.1 months. Tunnel placements of all the cases were measured on 3D CT. Clinical results were collected after reconstruction; graft’s appearance, meniscus status and cartilage state under arthroscopy were compared and analysed too.

Results

Tunnel placements, confirmed with 3D CT, were in the anatomic positions as described in literature both in SB and DB group. No differences were found between SB and DB groups in clinical outcome scores, pivot shift test and KT 1000 measurements (average side-to-side difference for anterior tibial translation was 0.7 mm in SB group and 1.0 mm in DB group). More than 70 % of the single-bundle graft and AM bundle graft in DB group appeared excellent, but only 44.1 % of PL bundle grafts in DB group were excellent and 11.8 % were in poor state. No new menisci tear was found either in SB or DB group, however, in DB group cartilage damages in medial patella-femoral joint occurred in 38.2 % cases. This rate was significantly higher than in the SB group which is only 9.3 %.

Conclusion

Both single- and double-bundle anatomic ACL reconstruction can restore the knee’s stability and functions very well. However, more incidences of poor PL status and medial patellar-femoral cartilage damage may occur in double-bundle ACL reconstruction.

Level of evidence

Randomized controlled trial, Level I.     

Anatomic double-bundle versus single-bundle ACL reconstruction: a comparative biomechanical study in rabbits

Thirty New Zealand white rabbits underwent anterior cruciate ligament (ACL) reconstruction in their right knees; 15 animals underwent a double-bundle anatomic ACL reconstruction using the medial third of the patellar tendon and the semitendinosus tendon. Additionally, 15 animals underwent ACL reconstruction, using a single-bundle semitendinosus tendon autograft. The knees of both groups were evaluated with a device similar to the KT1000 arthrometer onto which a dial indicator was attached (Mitutoyo dial indicator 2050) in 30° and 90° of flexion, preoperatively, after ACL resection and 3 months postoperatively. Statistical analysis of the results revealed that for 90° of knee flexion, the mean estimated anterior shift for the double-bundle technique was 1.92 mm lesser than that of the single-bundle technique (P = 0.006). For 30° of knee flexion, the mean anterior shift was again lesser than that of the single-bundle technique by 0.66 mm, but this difference was not statistically significant. The described double-bundle ACL reconstruction technique resulted in a more stable knee as far as the anterior tibial shift was concerned as compared to a single-bundle ACL reconstruction. This animal model may be potentially useful in the future for the study of other parameters influencing the outcome of the double-bundle ACL reconstruction.     

Increased odds of patient-reported success at 2 years after anterior cruciate ligament reconstruction in patients without cartilage lesions: a cohort study from the Swedish National Knee Ligament Register

Purpose

To investigate whether the surgical technique of single-bundle anterior cruciate ligament (ACL) reconstruction, the visualization of anatomic surgical factors and the presence or absence of concomitant injuries at primary ACL reconstruction are able to predict patient-reported success and failure. The hypothesis of this study was that anatomic single-bundle surgical procedures would be predictive of patient-reported success.

Methods

This cohort study was based on data from the Swedish National Knee Ligament Register during the period of 1 January 2005 through 31 December 2014. Patients who underwent primary single-bundle ACL reconstruction with hamstring tendons were included. Details on surgical technique were collected using an online questionnaire comprising essential anatomic anterior cruciate ligament reconstruction scoring checklist items, defined as the utilization of accessory medial portal drilling, anatomic tunnel placement, the visualization of insertion sites and pertinent landmarks. A univariate logistic regression model adjusted for age and gender was used to determine predictors of patient-reported success and failure, i.e. 20th and 80th percentile, respectively, in the Knee injury and Osteoarthritis Outcome Score (KOOS), 2 years after ACL reconstruction.

Results

In the 6889 included patients, the surgical technique used for single-bundle ACL reconstruction did not predict the predefined patient-reported success or patient-reported failure in the KOOS₄. Patient-reported success was predicted by the absence of concomitant injury to the meniscus (OR = 0.81 [95% CI, 0.72–0.92], p = 0.001) and articular cartilage (OR = 0.70 [95% CI, 0.61–0.81], p < 0.001). Patient-reported failure was predicted by the presence of a concomitant injury to the articular cartilage (OR = 1.27 [95% CI, 1.11–1.44], p < 0.001).

Conclusion

Surgical techniques used in primary single-bundle ACL reconstruction did not predict the KOOS 2 years after the reconstruction. However, the absence of concomitant injuries at index surgery predicted patient-reported success in the KOOS. The results provide further evidence that concomitant injuries at ACL reconstruction affect subjective knee function and a detailed knowledge of the treatment of these concomitant injuries is needed.

Level of evidence

Retrospective cohort study, Level III.

     

Anatomic single- and double-bundle anterior cruciate ligament reconstruction, part 2: clinical application of surgical technique

The anterior cruciate ligament has been and is of great interest to scientists and orthopaedic surgeons worldwide. Anterior cruciate ligament reconstruction was initially performed using an open approach. When the approach changed from open to arthroscopic reconstruction, a 2- and, later, 1-incision technique was applied. With time, researchers found that traditional arthroscopic single-bundle reconstruction did not fully restore rotational stability of the knee joint and a more anatomic approach to reconstruct the anterior cruciate ligament has been proposed. Anatomic anterior cruciate ligament reconstruction intends to replicate normal anatomy, restore normal kinematics, and protect long-term knee health. Although double-bundle anterior cruciate ligament reconstruction has been shown to result in better rotational stability in both biomechanical and clinical studies, it is vital to differentiate between anatomic and double-bundle anterior cruciate ligament reconstruction. The latter is merely a step closer to reproducing the native anatomy of the anterior cruciate ligament; however, it can still be done nonanatomically. To evaluate the potential benefits of reconstructing the anterior cruciate ligament in an anatomic fashion, accurate, precise, and reliable outcome measures are needed. These include, for example, T2 magnetic resonance imaging mapping of cartilage and quantification of graft healing on magnetic resonance imaging. Furthermore, there is a need for a consensus on which patient-reported outcome measures should be used to facilitate homogeneous reporting of outcomes.     

Anterior cruciate ligament reconstruction after unicompartmental knee arthroplasty

Purpose  

ACL deficiency may cause abnormal knee kinematics and is associated with a tenfold increase in surgical failures after unicompartmental knee arthroplasty, such as aseptic loosening of the tibial compartment and medial bearing instability. The current investigators hypothesized that in a knee with UKA, single-bundle ACL reconstruction would restore tibiofemoral translation to levels similar to those of the intact ACL.     

Effect of meniscal loss on knee stability after single-bundle anterior cruciate ligament reconstruction

Purpose

The menisci are known to be important secondary constraints to anterior translation of the tibia in the ACL-deficient knee. The effect of meniscal loss on knee stability as measured by the magnitude of the pivot shift following ACL reconstruction is unknown. The objective of this investigation was to determine the effect of meniscectomy on knee stability following two single-bundle ACL reconstruction strategies.

Materials and Methods

A mechanized pivot shift was performed on cadaveric specimens in the ACL-intact and ACL-deficient state. Tibiofemoral translation was recorded using a surgical navigation system. The ACL was reconstructed utilizing a nonanatomic graft (n = 10) extending from the posterolateral tibial footprint to the anteromedial femoral footprint, or an anatomic anteromedial single-bundle graft extending from the anteromedial tibial footprint to the anteromedial femoral footprint (n = 10) and testing repeated. The medial or lateral meniscus was sectioned and the examination repeated. The other meniscus was sectioned and the examination subsequently repeated.

Results

Lateral compartment translation during the pivot shift was significantly reduced following anatomic ACL reconstruction. In the nonanatomic group, lateral compartment translation increased by 9.1 mm (P < 0.001) after unicomparmental meniscectomy and 11.5 mm (P < 0.001) after bicompartmental meniscectomy. In the anatomic reconstruction group, lateral compartment translation increased by 7.6 mm (P < 0.001) after bicompartmental meniscectomy.

Conclusion

With isolated ACL injury, anatomic single-bundle ACL reconstruction controlled the pivot shift during time zero testing. However, significant increases in lateral compartment translation during the pivot shift are seen following bicompartmental meniscectomy. Nonanatomic ACL reconstruction was less effective in controlling the pivot shift at time zero testing, and significant increases in lateral compartment translation during the pivot shift were seen following both unicomparmental and bicompartmental meniscectomy.

     

The effects of limb alignment on anterior cruciate ligament graft tunnel positions estimated from plain radiographs

Purpose  

The aims of this study were (1) to evaluate the femoral tunnel position after anatomic double-bundle and nonanatomic single-bundle reconstruction; (2) to evaluate the influence of rotation of the femur caused by limb malalignment on measurements of the position of the femoral ACL tunnel aperture relative to Blumensaat’s line.