In vivo three-dimensional imaging analysis of femoral and tibial tunnel locations in single and double bundle anterior cruciate ligament reconstructions

Ideal Combination of Anatomic Tibial and Femoral Tunnel Positions for Single-Bundle ACL Reconstruction

Background:

Anatomic anterior cruciate ligament reconstruction (ACLR) is preferred over nonanatomic ACLR. However, there is no consensus on which point the tunnels should be positioned among the broad anatomic footprints.

Purpose/Hypothesis:

To identify the ideal combination of tibial and femoral tunnel positions according to the femoral and tibial footprints of the anteromedial (AM) and posterolateral (PL) anterior cruciate ligament bundles. It was hypothesized that patients with anteromedially positioned tunnels would have better clinical scores, knee joint stability, and graft signal intensity on follow-up magnetic resonance imaging (MRI) than those with posterolaterally positioned tunnels.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 119 patients who underwent isolated single-bundle ACLR with a hamstring autograft from July 2013 to September 2018 were retrospectively investigated. Included were patients with clinical scores and knee joint stability test results at 2-year follow-up and postoperative 3-dimensional computed tomography and 1-year postoperative MRI findings. The cohort was divided into 4 groups, named according to the bundle positions in the tibial and femoral tunnels: AM-AM (n = 33), AM-PL (n = 26), PL-AM (n = 29), and PL-PL (n = 31).

Results:

There were no statistically significant differences among the 4 groups in preoperative demographic data or postoperative clinical scores (Lysholm, Tegner, and International Knee Documentation Committee subjective scores); knee joint stability (anterior drawer, Lachman, and pivot-shift tests and Telos stress radiographic measurement of the side-to-side difference in anterior tibial translation); graft signal intensity on follow-up MRI; or graft failure.

Conclusion:

No significant differences in clinical scores, knee joint stability, or graft signal intensity on follow-up MRI were identified between the patients with anteromedially and posterolaterally positioned tunnels.

Systematic Review of Surgical Technique and Tunnel Target Points and Placement in Anatomical Single-Bundle ACL Reconstruction

The purpose of this systematic review was to reveal the trend in surgical technique and tunnel targets points and placement in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, data collection was performed. PubMed, EMBASE, and Cochran Review were searched using the terms "anterior cruciate ligament reconstruction," "anatomic or anatomical," and "single bundle." Studies were included when they reported clinical results, surgical technique, and/or tunnel placement evaluation. Laboratory studies, technical reports, case reports, and reviews were excluded from this study. From these full article reviews, graft selection, method of creating the femoral tunnel, and femoral and tibial tunnel target points and placement were evaluated. In the 79 studies included for data evaluation, the selected grafts were: bone patella tendon bone autograft (12%), and hamstring autograft (83%). The reported methods of creating the femoral tunnel were: transportal technique (54%), outside-in technique (15%), and transtibial technique (19%). In the 60 studies reporting tunnel target points, the target point was the center of the femoral footprint (60%), and the center of the anteromedial bundle footprint (22%). In the 23 studies evaluating tunnel placement, the femoral tunnel was placed in a shallow-deep direction (32.3%) and in a high-low direction (30.2%), and the tibial tunnel was placed from the anterior margin of the tibia (38.1%). The results of this systematic review revealed a trend in anatomical single-bundle ACL reconstruction favoring a hamstring tendon with a transportal technique, and a tunnel target point mainly at the center of the ACL footprint. The level of evidence stated is Systematic review of level-III studies.

3D CT evaluation of femoral and tibial tunnels in anatomic double bundle anterior cruciate ligament reconstruction

BACKGROUND

An anatomical double bundle ACL reconstruction replicates the anatomy of native ACL as the tunnels are made to simulate the anatomy of ACL with AM and PL bundle foot prints. The goal of anatomic ACL reconstruction is to tailor the procedure to each patient's anatomic, biomechanical and functional demands to provide the best possible outcome. The shift from single bundle to double bundle technique and also from transtibial to transportal method has been to provide near anatomic tunnel positions.

PURPOSE

To determine the position of femoral and tibial tunnels prepared by double bundle ACL reconstruction using three dimensional Computed tomography.

STUDY DESIGN

A prospective case series involving forty patients with ACL tear who underwent transportal double bundle ACL reconstruction.

METHOD

Computed tomography scans were performed on forty knees that had undergone double bundle anterior cruciate ligament reconstruction. Three-dimensional computed tomography reconstruction models of the knee joint were prepared and aligned into an anatomical coordinate axis system for femur and tibia respectively. Tibial tunnel centres were measured in the anterior-to-posterior and medial-to-lateral directions on the top view of tibial plateau and femoral tunnel centres were measured in posterior to anterior and proximal-to-distal directions with anatomic coordinate axis method. These measurements were compared with published reference data.

RESULTS

Analysing the Femoral tunnel, the mean posterior-to-anterior distances for anteromedial and posterolateral tunnel centre position were 46.8% ± 7.4% and 34.5% ± 5.0% of the posterior-to-anterior height of the medial wall and the mean proximal-to-distal distances for the anteromedial and posterolateral tunnel centre position were 24.1% ± 7.1% and 61.6% ± 4.8%. On the tibial side, the mean anterior-to-posterior distances for the anteromedial and posterolateral tunnel centre position were 28.8% ± 4.3% and 46.2% ± 3.6% of the anterior-to posterior depth of the tibia measured from the anterior border and the mean medial-to-lateral distances for the anteromedial and posterolateral tunnel centre position were 46.5% ± 2.9% and 50.6% ± 2.8% of the medial-to-lateral width of the tibia measured from the medial border. There is high Inter-observer and Intra-observer reliability (Intra-class correlation coefficient).

DISCUSSION AND CONCLUSION

Femoral AM tunnel was positioned significantly anterior and nearly proximal whereas the femoral PL tunnel was positioned significantly anterior and nearly distal with respect to the anatomic site. Location of tibial AM tunnel was nearly posterior and nearly medial whereas the location of tibial PL tunnel was very similar to the anatomic site Evaluation of location of tunnels through the anatomic co-ordinate axes method on 3D CT models is a reliable and reproducible method. This method would help the surgeons to aim for anatomic placement of the tunnels. It also shows that there is scope for improvement of femoral tunnel in double bundle ACL reconstruction through transportal technique.

[Histological properties of autogenous hamstring grafts after anterior cruciate ligament reconstruction]

Objective

To investigate the histological characteristics of autogenous hamstring grafts after anterior cruciate ligament (ACL) reconstruction.

Methods

The patients who underwent arthroscopic single-bundle ACL reconstruction with autogenous hamstring tendons and were followed up at least 4 years and also underwent second-look arthroscopy between March 2017 and December 2017 and met the selection criteria were considered for enrollment. Graft quality under arthroscopy was evaluated as good remodeling group (GRG, the total scores were 4-6) and poor remodeling group (PRG, the total scores were 1-3) according to synovial and vascular coverage, the apparent tension of the grafts, the thickness and retear of the grafts. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues harvested from the patients under 60 years old who underwent total knee arthroplasty were designated as normal controls. Graft vascularity, cellular morphology, cellular metabolism, and collagen fibril distribution were analyzed.

Results

The 18 specimens (11 cases of GRG group and 7 cases of PRG group) and 9 native ACL biopsied tissue sample were enrolled into the study. Arthroscopy scores were 2-6 (mean, 4.7). The biology under light microscopy of GRG group was similar to that of native ACL in control group. There was no significant difference in the scores of graft vascularity and cellular morphology between GRG group and control group ( P>0.05), while PRG group was significantly lower than the other two groups ( P<0.05). Transmission electron microscope evaluation showed that GRG group and control group had better collagen fibril distribution and lower levels of cellular metabolism than PRG group ( P<0.05). There was no significant difference in cellular metabolism between GRG and control groups ( P>0.05), while collagen fibril distribution score of GRG group was significantly lower than that of control group ( P<0.05).

Conclusion

While good remodeling grafts under arthroscopy in histological maturation period was proved to be more similar to normal ACL on ultrastructure properties under light and electron microscope, ultra structural differences regarding collagen fibril distribution still persist.

How to evaluate bone tunnel widening after ACL reconstruction - a critical review

Background

Comparing different imaging modalities and methods for assessment tunnel widening after ACL reconstruction and providing a detailed evidence-based literature overview.

Methods

PubMed was searched from 1970 to 2016 using the terms "ACL reconstruction" and "tunnel" and "imaging" or "CT" or "computerized tomography" or "MRI" or "magnetic resonance imaging" or "radiographs". 647 studies were found. 575 articles were excluded due to absence of specific radiological measurement methods of tunnel widening and 40 due to repetition of a previously published radiological measurement method. 32 articles were included reporting interand intraobserver reliabilities of tunnel measurement methods after ACL reconstruction.

Results

A variety of different algorithms and measurement methods using radiographs, magnetic resonance imaging, computed tomography or SPECT/CT evaluating tunnel position and bone tunnel enlargement have been described. Tunnel delination restricts an exact analysis using X-ray. Measurements using CT or MR were mostly obtained perpendicular to the tunnel axis or using specialized software for tunnel volume calculation in 3D.Based on the review the width of the femoral and tibial tunnels should be assessed perpendicular to the tunnel axis at different levels in relation to the joint. At least one measurement should be performed at the tunnel entrance, exit and midpoint of the tunnel.

Conclusion

CT should be considered the gold standard assessing tunnel widening in patients after ACL reconstruction. If specialized software is available calculating the tunnel volume, measurements should be preferably performed in 3D CT.

Level of evidence

II.

Femoral Tunnel Positioning in Anterior Cruciate Ligament Reconstruction: Anteromedial Portal versus Transtibial Technique-A Randomized Clinical Trial

Purpose  The purpose of this study was to investigate, through three-dimensional computed tomography (3D-CT), the accuracy of femoral tunnel positioning in patients undergoing anterior cruciate ligament (ACL) reconstruction, comparing transtibial (TT) and anteromedial (AM) techniques.

Methods  We evaluated postoperative 3D-CT scans of 26 patients treated with ACL reconstruction with hamstrings autograft using a low accessory AM portal technique and 26 treated with the TT technique. The position of the femoral tunnel center was measured with the quadrant method.

Results  Using quadrant method on CT scans, femoral tunnels were measured at a mean of 32.2 and 28.1% from the proximal condylar surface (parallel to Blumensaat line) and at a mean of 31.2 and 15.1% from the notch roof (perpendicular to Blumensaat line) for the AM and TT techniques, respectively.

Conclusion  The AM portal technique provides more anatomical graft placement than TT techniques.

Level of Evidence  Level I, randomized clinical study.

The Relationship Between ACL Femoral Tunnel Position and Postoperative MRI Signal Intensity

BACKGROUND

The purpose of this study was to find the ideal femoral tunnel position in single-bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT) by comparing clinical scores, stability of the knee joint, and graft signal intensity on follow-up magnetic resonance imaging (MRI). We hypothesized that positioning the femoral tunnel near the anteromedial bundle or center would lead to better results in terms of clinical outcomes and graft signal intensity on follow-up MRI than would positioning the tunnel near the posterolateral bundle.

METHODS

Two hundred patients underwent arthroscopic single-bundle ACL reconstruction with a soft-tissue graft; all patients had the same surgeon, surgical technique (anteromedial transportal technique), and rehabilitation protocol. Each patient underwent 3D-CT within 1 week after the operation and MRI at 1 year after the operation. Outcomes were evaluated in terms of clinical scores and the stability of the knee joint. We classified patients into three groups based on the femoral tunnel position: the anteromedial position group, the posterolateral position group, and the center position group. We evaluated graft signal intensity on follow-up MRI.

RESULTS

This study included 77 patients: 25 patients in the anteromedial position group, 15 patients in the posterolateral position group, and 33 patients in the center position group. Four patients had an eccentric tunnel position and were excluded. The 3 groups did not differ significantly (p > 0.05) in preoperative demographic characteristics. There were no significant differences (p > 0.05) between groups in clinical outcomes. However, patients in the anteromedial position group and in the center position group had better graft signal intensity on follow-up MRI than those in the posterolateral position group.

CONCLUSIONS

Positioning the femoral tunnel near the anteromedial bundle and center led to better graft signal intensity on follow-up MRI in anatomic single-bundle ACL reconstruction than did positioning the femoral tunnel near the posterolateral bundle. There were no differences in clinical scores or stability of the knee joint among the three groups.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Imaging the Anterior and Posterior Cruciate Ligaments

The anterior and posterior cruciate ligaments are important stabilizers of the knee joint function. Although they are both similar in their native appearance, they possess slightly different properties and complement each other's function. The imaging findings differ between the anterior and posterior cruciate ligaments. While MRI is the main imaging modality, radiographs and CT have a role in pre- and post-operative imaging. The aim of this review is to present pre-and post-operative imaging findings of injured cruciate ligaments. A special emphasis will be placed on the potential pitfalls in cruciate ligament imaging.

Remnant-Preserving Tibial Tunnel Positioning Using Anatomic Landmarks in Double-Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE

To assess (1) if 6 anatomic landmarks (ALs) could be arthroscopically confirmed with remnant preservation and (2) if creating tibial tunnels using these landmarks reduces individual variation and improves reproducibility in double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

We retrospectively reviewed data of patients who chronologically underwent double-bundle ACL reconstruction by either referencing the footprint after remnant dissection (non-AL group) or subsequently with the ALs (AL group). Using operative videos, 3 independent observers judged whether they could confirm 6 ALs (medial intercondylar ridge, medial and lateral intercondylar tubercles, anterior horn of lateral meniscus, Parsons' knob, and L-shaped ridge) in 20 patients randomly selected from the AL group. We then compared tunnel positions between the 2 groups, measured from the anterior and medial borders of the proximal tibia and expressed as percentage of the total depth and width of the proximal tibia using 3-dimensional computed tomography.

RESULTS

One hundred four patients (non-AL group, n = 54; AL group, n = 50) were included. All 6 ALs were arthroscopically confirmed in most cases (89.7% to 100%). The mean percentages of the anteroposterior (AP) depth for anteromedial (AM) tunnel, mediolateral (ML) width for AM tunnel, AP depth for posterolateral (PL) tunnel, and ML width for PL tunnel, respectively, were 27.8% ± 6.6%, 46.7% ± 2.8%, 41.4% ± 7.3%, and 46.1% ± 2.6% for the non-AL group and 30.7% ± 4.5%, 45.7% ± 2.2%, 45.2% ± 4.5%, and 46.9% ± 2.1% for the AL group, revealing significantly less variation in the AL group compared with the non-AL group, excluding the ML width of the PL tunnel (P = .007, .046, .002, .209, respectively).

CONCLUSIONS

Six landmarks could be reliably confirmed in cases with remnant preservation, and creating tibial tunnels using these landmarks were reproducible and resulted in less individual variation.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The effect of feedback from post-operative 3D CT on placement of femoral tunnels in single-bundle anatomic ACL reconstruction

PURPOSE

To evaluate the effect of feedback from post-operative 3D CT in the learning process of placing the femoral graft tunnel anatomically using the anteromedial (AM)-portal technique in single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

An experienced knee surgeon converting from transtibial to AM-portal technique was offered post-operative feedback on tunnel placement. Three groups of patients were included: transtibial drilling, (AM1) anteromedial drilling without feedback and (AM2) anteromedial drilling with post-operative CT feedback. Intra-articular landmarks were used as the only guidance for tunnel placement. Tunnel position was compared to an ideal anatomical ACL position using the Bernard and Hertel grid and visual feedback was given on tunnel placements. The effect of feedback was measured as the distance from the anatomical centre, and spread of tunnel placements on post-operative CT performed feedback was initiated.

RESULTS

When comparing the femoral tunnel placement to an ideal anatomical centre, there was an improvement in the mean tunnel position after (A) changing from a transtibial to an anatomical technique and a further improvement after (B) initializing the radiological feedback. There was a great variation of femoral tunnel localizations when initially only using intra-articular landmarks as guidance for tunnel placement--this variation, however, converged towards the anatomical centre throughout the feedback period and the AM2 group had a femoral tunnel closer (P = 0.001) to the anatomical centre than the AM1 group.

CONCLUSIONS

Post-operative 3D CT is effective in the learning process of placing femoral tunnels anatomically by giving post-operative feedback on tunnel placement. Bony landmarks and ACL remnants were found unreliable as the only guidance for femoral tunnel placement in the AM-portal technique-therefore, the use of an aid is recommended to reduce unwanted tunnel variations in a learning phase.

LEVEL OF EVIDENCE

Cohort Study, Level III.

Functional and computed tomography correlation of femoral and tibial tunnels in single-bundle anterior cruciate ligament reconstruction: Use of accessory anteromedial portal

BACKGROUND

An accessory anteromedial portal (AAMP) has been shown to be effective in placing an anatomically ideal femoral tunnel. It is well known that this is due to the independent femoral drilling which is possible with the AAMP. However very little is known regarding the significance of this reconstruction technique in influencing the functional outcomes of anatomic anterior cruciate ligament reconstruction (ACLR). This study documents the influence of tibial and femoral tunnel positions on functional outcomes of anatomic ACLR using the AAMP.

MATERIALS AND METHODS

41 patients who underwent anatomic ACLR between 2011 and 2013 were included in this prospective cohort study. The primary outcome involved the documentation of femoral and tibial tunnel positions with volume rendering imaging using a three-dimensional computed tomography (3D-CT) done at the end of 1 year. The tunnel position evaluations from the CT images were performed by an independent observer specializing in radiodiagnosis. Functional outcome measures included preoperative and postoperative Lysholm and International Knee Documentation Committee (IKDC) scores (subjective) documented by an independent investigator who was not involved with the surgical procedure, at the end of 1 year.

RESULTS

The minimum followup was 1 year. All patients achieved good clinical and functional outcomes postoperatively with no reported complications. Tunnel position evaluations with 3D-CT revealed the average tibial tunnel distance to be 15.5 mm (standard deviation [SD] =2.52) from the anterior border of the tibial plateau and the average femoral tunnel distance to be 14.33 mm (SD = 2.6) from the inferior margin of the medial surface of lateral femoral condyle and 13.72 mm (SD = 2.8) from the posterior margin of the medial surface of lateral femoral condyle. The average tunnel diameters were found to be 7.9 mm (SD = 0.72) for the tibial tunnels and 8.6 mm (SD = 1.07) for the femoral tunnels. Statistically significant correlation between the tibial tunnel distance and the IKDC scores with anterior placement of tibial tunnel were found; however, no such statistical relationship were found between the femoral tunnel positions and the functional outcome measures.

CONCLUSION

AAMP gives an ideal approach to drill the femoral tunnel independently. However, the influence of this tunnel placement on long term functional outcomes of ACLR needs to be assessed on larger cohort of patients.

Anatomic Placement of the Femoral Tunnels in Double-Bundle Anterior Cruciate Ligament Reconstruction Correlates With Improved Graft Maturation and Clinical Outcomes

PURPOSE

To compare maturation of reconstructed graft on second-look arthroscopy and clinical outcomes between 2 groups: the provisional anatomic (PA) group, with both the anteromedial (AM) and posterolateral (PL) femoral tunnels in their anatomic location, and the nonanatomic (NA) group, with either 1 of the 2 femoral tunnels beyond its anatomic location after double-bundle anterior cruciate ligament reconstruction.

METHODS

We enrolled 154 patients who underwent 3-dimensional computed tomography scanning and second-look arthroscopy after double-bundle anterior cruciate ligament reconstruction. All of the patients were divided into the PA and NA groups according to the femoral tunnel position determined by the quadrant method. Graft maturation was evaluated with 3 subsections, including integrity, tension, and synovial coverage with revascularization, on second-look arthroscopy. We also compared Lachman test, pivot-shift test, KT-2000 (MEDmetric, San Diego, CA), and International Knee Documentation Committee grades at the last follow-up.

RESULTS

Of the 154 patients, 88 were classified as the PA group and 66 as the NA group by the quadrant method. A difference existed between groups for the AM tunnel position but not for the PL tunnel position. The PA group showed a higher graft maturation score (P < .001 for all comparisons) and better results according to the International Knee Documentation Committee knee rating, Lachman test, pivot-shift test, and KT-2000 assessment (P < .001 for all comparisons).

CONCLUSIONS

The PA group with anatomic femoral tunnel placement showed a higher graft maturation score on second-look arthroscopy, along with better clinical outcomes, than the NA group. There was a significant difference in the AM femoral tunnel position but not in the PL tunnel position between the 2 groups.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Screw-Home Movement of the Tibiofemoral Joint during Normal Gait: Three-Dimensional Analysis

Background

The purpose of this study was to evaluate the screw-home movement at the tibiofemoral joint during normal gait by utilizing the 3-dimensional motion capture technique.

Methods

Fifteen young males and fifteen young females (total 60 knee joints) who had no history of musculoskeletal disease or a particular gait problem were included in this study. Two more markers were attached to the subject in addition to the Helen-Hayes marker set. Thus, two virtual planes, femoral coronal plane (P_f) and tibial coronal plane (P_t), were created by Skeletal Builder software. This study measured the 3-dimensional knee joint movement in the sagittal, coronal, and transverse planes of these two virtual planes (P_f and P_t) during normal gait.

Results

With respect to kinematics and kinetics, both males and females showed normal adult gait patterns, and the mean difference in the temporal gait parameters was not statistically significant (p > 0.05). In the transverse plane, the screw-home movement occurred as expected during the pre-swing phase and the late-swing phase at an angle of about 17°. However, the tibia rotated externally with respect to the femur, rather than internally, while the knee joint started to flex during the loading response (paradoxical screw-home movement), and the angle was 6°.

Conclusions

Paradoxical screw-home movement may be an important mechanism that provides stability to the knee joint during the remaining stance phase. Obtaining the kinematic values of the knee joint during gait can be useful in diagnosing and treating the pathological knee joints.

Ligamentization of Autogenous Hamstring Grafts After Anterior Cruciate Ligament Reconstruction: Midterm Versus Long-term Results

BACKGROUND

In previous studies, unimodal, small-diameter collagen fibrils have been commonly observed as the final collagen ultrastructure of the implanted grafts used in anterior cruciate ligament (ACL) reconstruction. However, the native ACL and hamstring tendon show bimodal collagen fibril distribution, consisting of both large- and small-diameter collagen fibrils.

HYPOTHESIS

Bimodal collagen fibril distribution of the graft is a common phenomenon after ACL reconstruction with hamstring tendon grafts and is time dependent.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 52 patients who underwent double-bundle ACL reconstruction using autogenous hamstring tendons and who also underwent second-look arthroscopic surgery were enrolled. The patients were divided into 2 groups according to the time interval between the 2 operations: the midterm group (27 patients), with a 13- to 30-month time interval between operations, and the long-term group (25 patients) with a 31- to 62-month interval. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues were harvested from 9 patients who underwent total knee replacement, and biopsy specimens of the to-be-grafted semitendinosus tendon tissues were also harvested from another 9 patients who underwent ACL reconstruction with hamstring tendons, which were designated as normal controls. Graft vascularity, cellularity, metaplasia, cellular metabolism, and collagen fibril distribution were analyzed.

RESULTS

Large-diameter (>100 nm) collagen fibrils were detected in 81.5% of the specimens in the midterm group and in 68.0% of the specimens in the long-term group. A typical bimodal distribution mode was observed in 62.6% of the specimens in the midterm group and in 52.0% of the specimens in the long-term group. There was no significant difference between groups with respect to the presence of large-diameter collagen fibrils, bimodal distribution, graft vascularity, cellularity, metaplasia, or cellular metabolic status.

CONCLUSION

Graft ultrastructural maturation, characterized by large-diameter collagen fibrils and a bimodal collagen fibril distribution, is a common phenomenon and is not time dependent in the midterm to long term.

CLINICAL RELEVANCE

After hamstring tendon ACL reconstruction, the implanted grafts can transform into ACL-like tissue with a similar ultrastructure and metabolism, implying their usefulness as grafts.

Volume and contact surface area analysis of bony tunnels in single and double bundle anterior cruciate ligament reconstruction using autograft tendons: in vivo three-dimensional imaging analysis

Background

Regarding reconstruction surgery of the anterior cruciate ligament (ACL), there is still a debate whether to perform a single bundle (SB) or double bundle (DB) reconstruction. The purpose of this study was to analyze and compare the volume and surface area of femoral and tibial tunnels during transtibial SB versus transportal DB ACL reconstruction.

Methods

A consecutive series of 26 patients who underwent trantibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft from January 2010 to October 2010 were included in this study. Three-dimensional computed tomography (3D-CT) was taken within one week after operation. The CT bone images were segmented with use of Mimics software v14.0. The obtained digital images were then imported in the commercial package Geomagic Studio v10.0 and SketchUp Pro v8.0 for processing. The femoral and tibial tunnel lengths, diameters, volumes and surface areas were evaluated. A comparison between the two groups was performed using the independent-samples t-test. A p-value less than the significance value of 5% (p < 0.05) was considered statistically significant.

Results

Regarding femur tunnels, a significant difference was not found between the tunnel volume for SB technique (1,496.51 ± 396.72 mm³) and the total tunnel volume for DB technique (1,593.81 ± 469.42 mm³; p = 0.366). However, the total surface area for femoral tunnels was larger in DB technique (919.65 ± 201.79 mm²) compared to SB technique (810.02 ± 117.98 mm²; p = 0.004). For tibia tunnels, there was a significant difference between tunnel volume for the SB technique (2,070.43 ± 565.07 mm³) and the total tunnel volume for the DB technique (2,681.93 ± 668.09 mm³; p ≤ 0.001). The tibial tunnel surface area for the SB technique (958.84 ± 147.50 mm²) was smaller than the total tunnel surface area for the DB technique (1,493.31 ± 220.79 mm²; p ≤ 0.001).

Conclusions

Although the total femoral tunnel volume was similar between two techniques, the total surface area was larger in the DB technique. For the tibia, both total tunnel volume and the surface area were larger in DB technique.