Computed tomography analysis of the femoral tunnel position and aperture shape of transportal and outside-in ACL reconstruction: do different anatomic reconstruction techniques create similar femoral tunnels?

It is challenging to reproduce both anatomical and functional aspects of anterolateral reconstruction: postoperative 3D-CT analysis of the femoral tunnel position

BACKGROUND

This study aimed to evaluate the femoral tunnel position and fiber length of the anterolateral ligament (ALL) reconstruction compared with the natural anatomy of the ALL. We also evaluated whether the femoral tunnel position would affect residual pivot shift.

METHODS

This study was a retrospective review of 55 knees that underwent ALL reconstruction considering the anatomical and functional aspects, during primary anterior cruciate ligament (ACL) reconstruction in the presence of a high-grade pivot shift or revisional ACL reconstruction. We determined the position of the femoral tunnel and the length of graft using a three-dimensional (3D)-computed tomography (CT) model after ALL reconstruction. We also measured graft excursion during surgery and examined pivot shift 2 years after surgery. We conducted a subgroup analysis of femoral tunnel position, fiber length, isometricity, and residual pivot shift depending on whether the tunnel was anterior or posterior to the lateral epicondyle (LE). We also performed a subgroup analysis depending on whether the ACL reconstruction was primary or revisional.

RESULTS

The mean femoral tunnel position was 2.04 mm posterior and 14.5 mm proximal from the center of the LE. The mean lengths of the anterior and posterior fibers were 66.6 and 63.4 mm, respectively. The femoral tunnel was positioned more proximally than the anatomical position, and both anterior and posterior ALL fibers were longer than the natural anatomy. The anteroposterior femoral tunnel position was significantly correlated with anterior (p = 0.045) and posterior (p = 0.037) fiber excursion. In the subgroup analysis, there was no significant difference in the residual pivot shift between the posterior and anterior tunnel positions. However, there were significant differences for proximal position (p < 0.001) and fiber length (p = 0.006). There was no significant difference between primary and revisional ACL regarding femoral tunnel position and fiber lengths.

CONCLUSION

It is challenging to reproduce both anatomical and functional aspects of ALL reconstruction in both primary and revision ACL reconstruction. Especially for functional reconstruction, the femoral tunnel tended to be positioned more proximally than the anatomical position. However, the femoral tunnel position did not affect functional clinical outcomes at the 2-year follow-up.

LEVEL OF EVIDENCE

Level IV Case series.

Posteromedial Portal Technique With Bone-Patellar Tendon-Bone Graft for Inside-Out Revision of Anterior Cruciate Ligament Reconstruction

Bone-patellar tendon-bone (BTB) is a graft material used in anterior cruciate ligament (ACL) reconstruction. We describe creating a femoral tunnel using an inside-out posteromedial (PM) portal technique during anatomic double-bundle ACL reconstruction with a hamstring graft. We hypothesized that applying this femoral tunnel creation method to the revision ACL reconstruction using BTB would enable reconstruction in 1 stage. In this technique, an anteromedial, an anterolateral, and a PM portal are created to confirm the original ACL footprint and location and direction of the bone tunnel during primary reconstruction. The surgeon then drills from the PM portal, so that the femoral tunnel opening touches the posterior proximal articular cartilage margin in the ACL footprint. Even if the opening partially overlaps with the primary tunnel, it is possible to create a new tunnel with a different direction. Finally, the BTB graft is guided from the tibial tunnel to the femoral tunnel and fixed with interference screws. Intraoperative PM arthroscopic views can confirm that the femoral tunnel has been created, avoiding overlap, and that the revision ACL has been reconstructed. This procedure may be useful for 1-stage revision ACL reconstruction for reinjury after primary ACL reconstruction by other conventional procedures.

Transportal versus all-inside techniques of anterior cruciate ligament reconstruction: a systematic review

Background

Transportal (TP) and all-inside techniques (AIT) are the most commonly used anterior cruciate ligament (ACL) reconstruction procedures in current clinical practice. However, there is an ongoing debate over which procedure is superior. Therefore, the purpose of this systematic review was to evaluate and compare the clinical outcomes and complications of these two techniques to propose recommendations for future application. Our primary hypothesis was that AIT is a superior ACLR technique compared to TP.

Methods

A systematic literature review, using PRISMA guidelines, was conducted using PubMed, Medline, Google Scholar, and EMBASE, up to February 2021 to identify studies focusing on AIT and TP techniques of ACL reconstruction. We excluded animal experiments, cadaveric studies, retrospective studies, case reports, technical notes, and studies without quantitative data. Patients’ characteristics, surgical technical features, along with postoperative follow-up and complications were extracted and reported accordingly. Methodological quality of the included studies was assessed using the Modified Coleman Methodology Score (MCMS).

Results

A total of 44 studies were selected for this review, of which four were comparative studies. A total of 923 patients underwent AIT and 1678 patients underwent the TP technique for ACLR. A single semitendinosus graft was commonly used in the AIT compard to combined semitendinosus and gracilis graft in the TP group. The postoperative increase in International Knee Documentation Committee (IKDC), Lysholm, KT-1000, and Short Form-12 (physical and mental) scores were similar in the AIT group and the TP group. Contrastingly, the VAS pain score was significantly lower in the AIT group compared to the TP group. Furthermore, the pooled complication rates from all studies were similar between the two groups (AIT: 54 patients, 8.26% vs. PT: 55 patients, 6.62%). However, the four studies that prospectively compared AIT and TP techniques showed lesser complications in the AIT group than the TP group.

Conclusion

Since the future trend in orthopedic surgery is toward less invasive and patients’ satisfaction with good outcomes, AIT is a good alternative method considering preserving bony tissue and gracilis tendon with less post-operative pain, along with more knee flexor strength and equal outcomes compared to conventional ACL reconstruction surgery.

Level of Evidence II.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02872-x.

A Systematic Review of Randomized Controlled Trials in Anterior Cruciate Ligament Reconstruction: Standard Techniques Are Comparable (299 Trials With 25,816 Patients)

PURPOSE

To provide an overview of all published randomized controlled trials (RCTs) in anterior cruciate ligament reconstruction (ACLR) summarizing the available evidence.

METHODS

Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched the Cochrane FIGCentral Register of Controlled Trials, Ovid MEDLINE, and Embase for RCTs of ACLR from their inception to August 26, 2020. Outcome measure was whether RCTs reported statistically significant findings. RCTs were then classified according to their intervention groups in a narrative synthesis of the evidence.

RESULTS

In total, 299 RCTs met the inclusion criteria and were included with a total number of 25,186 patients. Only 30 RCTs (10%) reported significant differences between the intervention and the control groups. These included 101 RCTs on grafts, 20 RCTs on tunnel placements, 48 RCTs on graft fixation, 42 RCTs on single-bundle compared with double-bundle reconstructions, 11 RCTs on additional procedures, 11 RCTs on graft tensioning, 5 RCTs on timing of surgery, 25 RCTs on technical variations from standard techniques, 6 RCTs on ACL repair, 5 RCTs on navigation, 16 RCTs on perioperative management, and 9 RCTs on other aspects of ACLR. Only 14 RCTs (4.7%) reported outcomes beyond 10 years with greater allograft failures compared with autografts, high incidence of osteoarthritic changes in reconstructed knees (22%-100%), with no significant differences in outcomes between bioabsorbable or metal screws for graft fixation, patellar versus hamstrings or single- versus double-bundle reconstructions.

CONCLUSIONS

The evidence indicates that a standard arthroscopic single- or double-bundle ACLR with hamstrings/patella autografts, transportal technique, and fixation techniques familiar to the surgeon leads to comparable results. This evidence offers surgeons the flexibility to use standard and cost-effective techniques and achieve comparable outcomes.

LEVEL OF EVIDENCE

Level II; systematic review of Level I-II randomized controlled trials.

Remnant-Tensioning Single-Bundle Anterior Cruciate Ligament Reconstruction Provides Comparable Stability to and Better Graft Vascularity Than Double-Bundle Anterior Cruciate Ligament Reconstruction in Acute or Subacute Injury: A Prospective Randomized Controlled Study Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging

PURPOSE

To compare the clinical, second-look arthroscopic, magnetic resonance imaging (MRI), and dynamic-contrast-enhanced MRI (DCE-MRI) findings between remnant-tensioning single-bundle (RT-SB) and double-bundle (DB) anterior cruciate ligament reconstruction (ACLR).

METHODS

Sixty-seven patients with acute or subacute anterior cruciate ligament (ACL) injury were randomized to undergo RT-SB or DB ACLR. Twenty-six patients in the RT-SB group and 28 in the DB group were evaluated using stability tests (Lachman test, pivot-shift test, and KT-2000 arthrometer) and multiple clinical scores. One year postoperatively, all 54 patients underwent MRI for evaluation of graft continuity and graft signal/noise quotient and DCE-MRI for the calculation of normalized area under the curve (nAUC) as a marker of graft vascularity. Among them, 41 patients underwent second-look arthroscopy for the evaluation of graft continuity, graft tension, and synovialization. The results were compared between the 2 groups.

RESULTS

At the minimum 2-year follow-up (28.7 ± 6.4 months), the stability tests, clinical scores, second-look arthroscopic findings, and MRI findings were not significantly different between the groups. However, the mean nAUC values on DCE-MRI for the ACL graft were significantly higher in the RT-SB group than those in the DB group in all 3 zones (nAUC_proximal, P = .005; nAUC_middle, P = .021; nAUC_distal, P = .027; and nAUC_average, P = .008).

CONCLUSION

For acute or subacute ACL injury, the RT-SB ACLR showed an outcome comparable to that of DB ACLR in terms of knee stability, clinical scores, MRI findings, and second-look arthroscopic findings. Moreover, RT-SB ACLR showed better graft vascularity 1 year postoperatively than DB ACLR using DCE-MRI.

LEVEL OF EVIDENCE

II, prospective randomized controlled trial.

A comparison of femoral tunnel placement in ACL reconstruction using a 70° arthroscope through the anterolateral portal versus a 30° arthroscope through the anteromedial portal: a pilot 3D-CT study

Background

Graft malposition is a risk factor for failure of anterior cruciate ligament reconstruction. A 70° arthroscope improves visualisation of the medial wall of the lateral femoral condyle without switching portals. We investigated whether the use of this arthroscope affected the accuracy and precision of femoral tunnel placement.

Methods

Fifty consecutive adult patients were recruited. Following one withdrawal and two exclusions, 47 patients (30 in group 1 (70° arthroscope), 17 in group 2 (30° arthroscope)) underwent three-dimensional computed tomography imaging using a grid-based system to measure tunnel position.

Results

No difference was found in the accuracy or precision of tunnels (mean position: group 1 = 33.3 ± 6.0% deep–shallow, 27.2 ± 5.2% high–low; group 2 = 31.7 ± 6.9% deep–shallow, 29.0 ± 6.2% high–low; not significant). A post-hoc power analysis suggests a study of 106 patients would be required.

Conclusions

This pilot study suggests that tunnel position is not affected by the arthroscope used. An appropriately powered study could investigate this finding alongside other potential benefits of using a 70° arthroscope for this procedure.

Trial registration

ClinicalTrials.gov, NCT02816606. Registered on 28 June 2016.

Anatomic femoral tunnel placement is difficult by the transtibial technique: comparison of three different femoral tunnel drilling techniques in double-bundle anterior cruciate ligament reconstructions

PURPOSE

To compare the position and direction of femoral and tibial tunnels for both the anteromedial bundle (AMB) and posterolateral bundle (PLB) among three different femoral tunnel drilling techniques, transtibial (TT), transportal (TP), and outside-in (OI) techniques, in anatomic double-bundle ACL reconstruction to clarify advantages and disadvantages of each technique.

METHODS

One-hundred and thirty-nine patients underwent primary ACL reconstruction with an autologous semitendinosus tendon in our institution between 2014 and 2016. Thirteen patients were excluded according to the exclusion criteria. Of the 126 patients, 98 patients agreed to be included in this study. Patients were then randomized into three groups according to the femoral tunnel drilling technique; the TT, TP, and OI groups. Femoral and tibial tunnel angles and positions were measured using three-dimensional computed tomography.

RESULTS

Of patients who agreed to be included in this study, eight patients (seven in TT and one in OI) were excluded since the femoral tunnel could not be created at the intended position. Eighty-six patients (29 in TT, 29 in TP, and 28 in OI) were included for the analyses. Tunnel angles, as well as tunnel lengths, had significant differences among different techniques depending on each technique's characteristics. In terms of tunnel position, femoral tunnel positions of both the AMB and PLB in the TT group were significantly higher than those in the TP group (AMB: p = 0.003, PLB: p = 0.001), and the PLB tunnel position in the TP group had significantly smaller vaciance than that in the TT group (p = 0.004) and OI group (0.002).

CONCLUSIONS

The femoral tunnel positions created by the TT technique were significantly higher, with larger variance, than the TP technique in double-bundle ACL reconstruction, although the positions seemed to be within anatomical footprint. In addition, there were several cases in which femoral tunnels could not be created at the intended position by the TT technique.

LEVEL OF EVIDENCE

I.

Significant anterior enlargement of femoral tunnel aperture after hamstring ACL reconstruction, compared to bone-patellar tendon-bone graft

PURPOSE

This study aimed to retrospectively compare the enlargement and migration of the femoral tunnel aperture after anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction with a bone-patella tendon-bone (BTB) or hamstring tendon (HT) graft using three-dimensional (3-D) computer models.

METHODS

Thirty-two patients who underwent ACL reconstruction and postoperative computed tomography (CT) at 3 weeks and 6 months were included in this study. Of these, 20 patients underwent ACL reconstruction with a BTB graft (BTBR group), and the remaining 12 with an HT graft (HTR group). The area of the femoral tunnel aperture was extracted and measured using a 3-D computer model generated from CT images. Changes in the area and migration direction of the femoral tunnel aperture during this period were compared between the two groups.

RESULTS

In the HTR group, the area of the femoral tunnel aperture was significantly increased at 6 months compared to 3 weeks postoperatively (P < 0.05). The average area of the femoral tunnel aperture at 6 months postoperatively was larger by 16.0 ± 12.4% in the BTBR group and 41.9 ± 22.2% in the HTR group, relative to that measured at 3 weeks postoperatively (P < 0.05). The femoral tunnel aperture migrated in the anteroinferior direction in the HTR group, and only in the inferior direction in the BTBR group.

CONCLUSIONS

The femoral tunnel aperture in the HTR group was significantly more enlarged and more anteriorly located at 6 months after ACL reconstruction, compared to the BTBR group.

LEVEL OF EVIDENCE

IV.

Comparison of three approaches for femoral tunnel during double-bundle anterior cruciate ligament reconstruction: A case controlled study

BACKGROUND

It is still controversial whether which femoral tunnel creation technique is best during anterior cruciate ligament reconstruction (ACLR). We aimed to clarify the features of three different techniques based on the femoral tunnel position created with the same tunnel-creating concept and the measurement data.

METHODS

The femoral tunnel of double-bundle (DB) ACLR was created using the behind-remnant approach in a remnant preserved manner following the policy of our institute. The trans-tibial approach (TT) was applied for all primary ACL injured cases until December 2012. The trans-portal approach (TP) was applied from January to September 2013, and the outside-in approach (OI) was indicated from October 2013 to March 2014. We compared the femoral tunnel aperture positions with the postoperative three-dimensional computed tomography (3D-CT). Additionally, the femoral tunnel length and the septum distance of each anteromedial (AM) and posterolateral (PL) tunnel were analyzed.

RESULTS

The AM tunnel aperture position of TT was significantly higher and shallower than that of TP in knee flexion position. The femoral tunnel length of TP was significantly shorter than that of TT and OI. The septum between each tunnel of OI trended wider than that of TT and TP.

CONCLUSIONS

The AM tunnel aperture position of TT runs the risk of a high and shallow position. TP runs the risk of insufficiently short tunnel length. It is important to apply each method flexibly to each case because no single best approach was found.

Optimal Condition to Create Femoral Tunnel Considering Combined Influence of Knee Flexion and Transverse Drill Angle in Anatomical Single-Bundle ACL Reconstruction Using Medial Portal Technique: 3D Simulation Study

There has been no previous study using three-dimensional (3D) measurement on femoral tunnel characteristics according to the combined influence of various flexion angles of knee and transverse drill angles in single-bundle ACL reconstruction with transportal technique. The purpose of this study was to determine optimal condition of knee flexion angle and transverse drill angle to create secure femoral tunnel in single-bundle ACL reconstruction with transportal technique considering tunnel length, tunnel wall breakage, and graft bending angle. This study was conducted using simulation of 3D computed tomography of thirty subjects. Three variables of femoral tunnel changed according to combined influence of four flexion angles of knee and three transverse drill angles were measured: tunnel length, wall breakage, and graft bending angle. There was no case of short femoral tunnel less than 25 mm at 120° and 130° of flexion. There was no case of breakage of femoral tunnel at 120° of flexion with maximum transverse drill angle (MTA) and MTA-10° and at 130° of flexion. Considering effect on graft bending angle, decrease of flexion angle and transverse drill angle could be appropriate in creating femoral tunnel. Increased flexion angle and transverse drill angle secured femoral tunnel having sufficiently long length without wall breakage. However, avoiding excessive flexion angle and maximum transverse drill angle could be recommended because they tended to cause more acute graft bending angle.

Location of the femoral tunnel aperture during single-bundle posterior cruciate ligament reconstruction: outside-in versus inside-out techniques

PURPOSE

Placement of the femoral tunnel is critical to graft function after posterior cruciate ligament (PCL) reconstruction. To date, however, the location of the femoral tunnel aperture has not been compared by in vivo 3-dimensional computed tomography (3D-CT) during PCL reconstruction with the outside-in (OI) and inside-out (IO) techniques. This study used 3D-CT analysis to compare the location of the femoral tunnel aperture in patients who underwent PCL reconstruction with the OI and IO techniques.

METHODS

A total of 77 patients underwent single-bundle PCL reconstruction using the OI (n = 46) or IO (n = 31) technique. The location of the femoral tunnel aperture was assessed by 3D-CT and measured by the anatomic coordinate axis method to construct 3D surface models.

RESULTS

The mean location of the femoral tunnel aperture in the low-to-high direction did not differ significantly in the OI and IO groups (75.0 vs. 75.2%, P = 0.869). However, in the deep-to-shallow direction, the femoral tunnel aperture was positioned more shallowly in the IO than in the OI group (75.7 vs. 81.1%, P < 0.001).

CONCLUSION

The IO technique of single-bundle PCL reconstruction yielded a shallower femoral tunnel in the deep-to-shallow direction than did the OI technique. However, femoral tunnel location in the low-to-high direction was similar using the two techniques.

Comparison of Clinical Results, Second-Look Arthroscopic Findings, and MRI Findings Between the Transportal and Outside-In Techniques for Double-Bundle Anatomic Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized Controlled Trial With a Minimum 2-Year Follow-up

BACKGROUND

Although image analysis has shown that the outside-in (OI) technique is associated with different femoral tunnel geometry than the transportal (TP) technique in anatomic anterior cruciate ligament (ACL) reconstruction, it is not known whether clinical results differ between the 2 techniques.

PURPOSE

To compare clinical results, second-look arthroscopic findings, and magnetic resonance imaging (MRI) findings between the TP and OI techniques in anatomic double-bundle (DB) ACL reconstruction.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

From November 2010 to March 2013, 128 patients were enrolled in this study and were randomly assigned to either the TP group (64 patients) or the OI group (64 patients), and DB ACL reconstructions were performed. At the minimum 2-year follow-up (34.9 ± 10.9 months), 111 patients (86.7%) were evaluated with multiple clinical scores and stability tests (KT-2000 arthrometer, Lachman test, and pivot-shift test). Ninety-three knees were evaluated for graft continuity, graft tension, and synovialization by use of second-look arthroscopy. Seventy-eight knees were evaluated on MRI for graft continuity, femoral graft tunnel healing, and graft signal/noise quotient (SNQ). The primary outcome was KT-2000 arthrometer results. Results were compared between the TP and OI groups.

RESULTS

No significant differences were found between the 2 groups in terms of KT-2000 arthrometer results, which was the primary outcome, and other clinical results, with the exception of the postoperative functional test of International Knee Documentation Committee (IKDC) objective score. The ratio of grade A and B on the postoperative functional test of IKDC objective score was significantly larger for the OI group (51/58) than the TP group (36/53) ( P = .005). The second-look arthroscopic findings were not significantly different between the 2 groups in either bundle ( P > .05). In addition, MRI findings did not differ significantly between the 2 groups ( P > .05).

CONCLUSION

With the exception of the functional test of IKDC objective score, we found that clinical results, second-look arthroscopic findings, and MRI findings did not differ significantly between the OI and TP techniques for anatomic ACL reconstruction, although femoral tunnel geometries differed significantly between the 2 techniques.

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis

PURPOSE

To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft.

METHODS

Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12^®. 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations.

RESULTS

In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture.

CONCLUSION

In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture.

CLINICAL RELEVANCE

the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively.

LEVEL OF EVIDENCE

I.

Plain radiographs can be used for routine assessment of ACL reconstruction tunnel position with three-dimensional imaging reserved for research and revision surgery

PURPOSE

The position of the osseous tunnels and graft during anterior cruciate ligament (ACL) reconstruction has been the subject of multiple studies aiming for either anatomical placement or an alternative. The assessment of these positions, using post-operative imaging, is therefore of interest to the surgeon in both the evaluation of surgical performance and surveillance of potential complications. The purpose of this review is to identify the optimal use of imaging in both the surveillance of clinical practice and in planning revision surgery.

METHODS

A comprehensive systematic review was performed using Medline and Pubmed searches to identify radiological methods used to assess ACL reconstruction tunnel position. Commonly used methods were identified with correlation to either native anatomy or clinical results.

RESULTS

The findings suggest that plain radiographs can be used to assess tunnel position and identify grafts that are positioned non-anatomically and may be at increased risk of complications. Computer tomography (CT) offers additional information about the tunnel aperture shape and size that is of importance for revision surgery and research projects whilst magnetic resonance imaging (MRI) provides further assessment of both graft integrity and associated soft tissue damage.

CONCLUSION

In the surveillance of routine clinical practice, plain radiographs are sufficient to define tunnel position. The additional information provided by three-dimensional imaging is only required in revision surgery or research studies.

LEVEL OF EVIDENCE

IV.

Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis

BACKGROUND

The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique.

METHODS

Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed.

RESULTS

Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles.

CONCLUSION

Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle.

One-incision versus two-incision techniques for arthroscopically assisted anterior cruciate ligament reconstruction in adults

BACKGROUND

Anterior cruciate ligament (ACL) tears are serious knee injuries that are frequently treated surgically in the form of arthroscopically assisted reconstruction with grafts from the patella or hamstrings tendons. We reviewed the evidence for the choice of arthroscopically assisted ACL reconstruction technique in terms of whether it should involve one incision (femoral tunnel drilled from inside the knee joint under arthroscopic visualisation) or two incisions (femoral tunnel drilled from outside to inside the knee joint).

OBJECTIVES

To assess the effects (benefits and harms) of one-incision versus two-incision techniques for arthroscopically assisted ACL reconstruction in adults.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Latin American and Caribbean Health Sciences (LILACS), the World Health Organization International Clinical Trials Registry Platform, ClinicalTrials.gov, reference lists, and conference abstracts. The date of the search was 16 August 2017.

SELECTION CRITERIA

Randomised and quasi-randomised controlled clinical trials evaluating one-incision versus two-incision techniques for arthroscopically assisted ACL reconstruction in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched and selected studies, and extracted data and assessed the risk of bias of the eligible studies. We undertook limited pooling of data using the fixed-effect model.

MAIN RESULTS

We included five trials (four randomised and one quasi-randomised) evaluating a total of 320 participants who were mainly in their 20s. All participants underwent ACL reconstruction with patella tendon grafts. All five included trials were at a high risk of bias, particularly performance bias. Based on these limitations and the insufficiency of the available data resulting in imprecision of effect estimates, we judged the quality of the evidence as very low for all outcomes. This means that we are uncertain of the findings of the review.We found very low-quality evidence of no clinically important differences between the two techniques in self reported knee function, measured using the Lysholm knee score (scale 0 to 100: best outcome), at short-term (3 months) (mean difference (MD) 2.73 favours one-incision technique, 95% confidence interval (CI) -2.70 to 8.15; 79 participants, 2 studies), intermediate-term (12 months) (MD -3.68 favours two-incision technique, 95% CI -6.61 to -0.75; 79 participants, 2 studies), and long-term follow-up. The data available for long-term follow-up (2 to 5 years) was expressed in terms of the numbers of participants with excellent Lysholm scores (90 points or more); we found no difference between the two groups (42/45 versus 36/40; risk ratio (RR) 1.04, 95% CI 0.91 to 1.18; 1 study). There were no data for quality of life measures or for overall numbers of participants incurring an adverse event. We found very low-quality evidence of little between-group differences in individual adverse events such as infection, knee stiffness, reoperation, and graft failure.We found very low-quality evidence from one study (59 participants) of little difference between the two groups in activity levels measured using Tegner scores (scale 0 to 10: highest sport activity) at two years (MD -0.80 favours two-incision technique, 95% CI -1.90 to 0.30). There was very low-quality evidence from four studies of minimal between-group difference in the number of participants with normal or nearly normal objectively measured knee function (International Knee Documentation Committee objective assessment grading) at intermediate follow-up (means 12 to 28 months): 56/78 versus 63/89; RR 1.01, 95% CI 0.85 to 1.21; 167 participants).

AUTHORS' CONCLUSIONS

The very low-quality and often absent evidence means that we are uncertain whether one-incision arthroscopically assisted ACL reconstruction techniques yield better, worse, or equivalent results compared with two-incision techniques in terms of short-, intermediate-, or long-term subjective function, quality of life, adverse outcomes, activity levels, and objectively rated knee function. The evidence was available only for single-bundle ACL reconstruction using patella tendon grafts.When considering priorities for high-quality randomised trials on techniques for ACL reconstruction, it is important to note the insufficiency of the evidence available to inform this key comparison.

Comparison of anterior cruciate ligament volume after anatomic double-bundle anterior cruciate ligament reconstruction

BACKGROUD

To determine whether anatomic double-bundle anterior cruciate ligament reconstruction (DB-ACLR) can restore the native ACL volume, and whether the volume change after reconstruction affects clinical outcomes and re-rupture rates following the contemporary techniques.

METHODS

Eighty patients undergoing anatomic DB-ACLR using transportal or outside-in technique were prospectively evaluated with magnetic resonance imaging (MRI) before and after surgery. The ACL volumes were determined from 3-D models constructed by applying reverse engineering software. In all participants, measured reconstructed ACL volume were compared with the ACL on the opposite uninjured side. Participants were divided into two groups according to the volume of reconstructed graft; larger volume than native ACL of contra-lateral side (Group 1) or smaller (Group 2).

RESULTS

The mean ACL volume on the reconstructed side (1726.5mm³, 982.1 - 2733.8) was significantly smaller than that on the uninjured opposite side (1857.6mm³, 958.2 - 2871.5) (P<0.001). A total of 31 patients in Group 1 and 49 in Group 2 showed no significant difference of improvement in the clinical outcome scales at the postoperative two-year follow-up (Lysholm knee score, P=0.830, Tegner activity score, P=0.848). Four patients with ACL re-rupture during the two-year follow-up after reconstruction had smaller reconstructed ACL volumes than native ligament on the opposite site.

CONCLUSION

Anatomic DB-ACLR technique restored the graft volume rather smaller than the volume of the native ACL. Based on the volumetric consideration, graft reconstructed by anatomic DB-ACLR might have increased probability of re-rupture due to its smaller volume related to native ACL on the contralateral side.

Comparison of transportal and outside-in techniques for posterolateral femoral tunnel drilling in double-bundle ACL reconstruction -three-dimensional CT analysis of bone tunnel geometry

PURPOSE

To comparatively analyze the geometry of the posterolateral femoral (PL) tunnel in double-bundle ACL reconstruction between far anteromedial transportal (TP) and outside-in (OI) drilling techniques based on three-dimensional computed tomography (3DCT) image analysis.

METHODS

Forty patients who underwent anatomic double-bundle hamstring ACL reconstruction using the TP (n: 20) or OI (n: 20) method with postoperative CT data available were included in the study. The analyzed parameters were as follows: location of the intraarticular tunnel aperture, tunnel length, bending angle (angulation of the graft at the intraarticular tunnel aperture), and long axis of the tunnel aperture/drill diameter ratio as a parameter of ellipsoidal geometry.

RESULTS

Anatomical tunnel placement was achieved in both groups. Coalition of the AM and PL tunnel apertures was found in 3 knees in the TP group and 1 knee in the OI group, though no significant difference in the rate of this problem was demonstrated between the groups (P: 0.30). The tunnel length was not significantly different between the groups, while the graft bending angle at the tunnel aperture was significantly larger in the OI group than the TP group (99.4° vs. 63.6°). The long axis/drill diameter ratio averaged 1.23 in the TP group and 1.13 in the OI group with significant intergroup difference.

CONCLUSION

When drilling the PL femoral tunnel in double-bundle ACL reconstruction, anatomic placement of the intraarticular tunnel aperture was feasible in both the TP and OI techniques. The tunnel aperture was rounder and the graft bending angle in knee extended position at the intraarticular aperture was more acute in the OI technique than the TP technique.

LEVEL OF EVIDENCE

Level IV (retrospective comparison of the two patient groups treated at different hospitals).

Three-Dimensional Reconstruction Computed Tomography Evaluation of the Tunnel Location and Angle in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction: A Comparison of the Anteromedial Portal and Outside-in Techniques

Purpose

The purpose of this study was to compare the geometry and position of the femoral tunnel between the anteromedial portal (AMP) and outside-in (OI) techniques after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction.

Materials and Methods

We evaluated 82 patients undergoing single-bundle ACL reconstruction with hamstring autografts using either the AMP (n=40) or OI (n=42) technique. The locations of the tunnel apertures were assessed by postoperative 3-dimensional computed tomography imaging. The femoral graft bending angle, femoral tunnel aperture shape, femoral tunnel length, and posterior wall breakage were also measured.

Results

The mean femoral tunnel position parallel to the Blumensaat line was more caudally positioned in the AMP group than in the OI group (p=0.025) The mean femoral graft angle in the OI group (99.6°±7.1°) was significantly more acute than that of the AMP group (108.9°±10.2°, p<0.001). The mean height/width ratio of the AMP group (1.21±0.20) was significantly more ellipsoidal than that of the OI group (1.07±0.09, p<0.001).

Conclusions

The mean femoral tunnel position was significantly shallower in the AMP technique than in the OI technique. The OI technique might be more disadvantageous than the AMP technique in terms of the more acute bending angle.

Clinical and arthrometric outcomes of an anatomic outside-in single-bundle anterior cruciate ligament reconstruction using a retrodrill

BACKGROUND

The main option to perform an anatomic anterior cruciate ligament (ACL) reconstruction is the anteromedial portal (AMP) technique. It has several reported complications (iatrogenic chondral injury, posterior-wall blowout, short sockets, increased risk of injury to common peroneal nerve). In an attempt to avoid these complications the outside-in (OI) technique was revived with the addition of a retrodrill. The aim of this study is to evaluate the clinical and arthrometric outcomes of a series of anatomical OI single bundle ACL reconstruction using a retrodrill.

METHODS

Prospective case series. KT-1000 and Pivot Shift Test were done at 24 months follow-up. International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scores preoperatively and at final follow-up. Complications were reported. Statistical analysis was done with t-test.

RESULTS

275 knees of 200 (73%) males and 75 (27%) females were enrolled in the study. Mean age 29.1 years (15-54). Mean follow-up 34.5 months (24-49). Mean preoperatively Lysholm Score 62 (25-95) versus 95 (76-100) at final follow-up (p<0.001) Mean preoperatively IKDC score 60 (26.4-90.8) versus 92 (59.8-100) at final follow-up (p<0.001) Mean Tegner activity Score pre injury 5 versus 5 at final follow-up. (p=0.59) Mean KT-1000 side-to-side difference 2mm (1-6). Pivot Shift test negative in 243 patients (90%); positive in 32 (10%) patients. 13 (5%) ACL re-ruptures. 2 (0.7%) infections. No other complications were reported.

CONCLUSION

OI single bundle anatomic ACL reconstruction using a retrodrill is a valid and safe option that avoids the complications reported with the AMP technique.

Clinical advantages of image-free navigation system using surface-based registration in anatomical anterior cruciate ligament reconstruction

PURPOSE

To evaluate the clinical advantages of a navigation system developed with an emphasis on attaining an appropriate femoral tunnel length and posterior wall margin with no posterior wall blowout, as well as having accurate tunnel positioning, in anatomical anterior cruciate ligament reconstruction (ACLR).

METHODS

Ten freshly frozen human knees were transected at mid-femur and mid-tibia. Each knee specimen underwent arthroscopic single-bundle anterior cruciate ligament reconstruction using the outside-in technique, with two knees by manual ACLR (control group) and another eight knees by only the navigational ACLR without arthroscopic assistance (experimental group). The position/orientation information of tunnel entry point, tunnel length, and posterior wall distance of pre-, intra-, and postoperative tunnel were recorded, and the reliability and errors among them were evaluated.

RESULTS

From comparison of the 3D models for preoperative planning and postoperative reconstruction, the mean differences for navigational femoral tunnelling and arthroscopic-assisted femoral tunnelling were recorded, respectively: (1) tunnel entry position, 1.4 mm (SD 0.3) versus 4.9 mm; (2) tunnel length, 0.7 mm (SD 0.2), similar to 0.6 mm in arthroscopic-assisted femoral tunnelling, and (3) posterior wall distance, 0.5 mm (SD 0.2), much smaller than 4.7 mm for arthroscopic-assisted femoral tunnelling. The intraclass correlation coefficients, calculated to determine the accuracy and reliability of navigational femoral tunnelling, showed excellent internal consistency that ranged from 0.965 to 0.989 for tunnel length and from 0.810 to 0.953 for posterior wall distance.

CONCLUSION

Navigation systems with enhancement of the registration accuracy by the developed system are feasible in anatomical ACLR, in reducing surgical failures such as short tunnel length or posterior wall breakage of distal femur. The present study revealed that computer navigation could aid in avoiding major mistakes in exact positioning and posterior wall blowout and help in attaining appropriate length for femoral tunnelling in anatomical ACLR.

Comparison of Femoral Tunnel Length and Obliquity Between Transtibial, Anteromedial Portal, and Outside-In Surgical Techniques in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Meta-analysis

PURPOSE

It is unclear whether femoral tunnel length and obliquity differ after transtibial and independent femoral drilling techniques of anterior cruciate ligament (ACL) reconstruction. This meta-analysis therefore compared femoral tunnel length and obliquity in patients who underwent ACL reconstruction by the transtibial, anteromedial (AM) portal, and outside-in (OI) techniques.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, all studies comparing femoral tunnel length and obliquity with various measurement tools-from direct measurement to imaging methods such as plain radiography, computed tomography, or magnetic resonance imaging-in patients who underwent reconstruction by the transtibial or independent femoral drilling (AM portal or OI) techniques were included.

RESULTS

Fourteen studies were included in the meta-analysis. The femoral tunnel length was 7.8 to 11.0 mm longer (P < .05) and coronal obliquity was 7.5° to 29.1° more vertical (P < .05) with the transtibial technique than with the AM portal or OI technique. Femoral tunnel and graft obliquity in the sagittal plane, however, did not differ significantly (P > .05).

CONCLUSIONS

ACL reconstruction using the AM portal and OI femoral drilling techniques resulted in a shorter length and greater coronal obliquity of the femoral tunnel than did the transtibial technique. However, these 3 femoral drilling techniques resulted in similar obliquities of the femoral tunnel and graft in the sagittal plane.

LEVEL OF EVIDENCE

Level III, meta-analysis.

Morphological changes in femoral tunnels after anatomic anterior cruciate ligament reconstruction

PURPOSE

Few studies investigated the enlargement inside the tunnel as well as the morphological change at the aperture after anterior cruciate ligament (ACL) reconstruction, whereas the tunnel enlargement has been well documented. The purposes were to evaluate the change in the cross-sectional area along the femoral tunnel and to morphologically clarify the enlargement at the femoral tunnel aperture after anatomic triple-bundle (ATB) ACL reconstruction.

METHODS

The study included 15 patients with unilateral ACL rupture. ATB ACL reconstruction was performed using semitendinosus tendon autografts. Three-dimensional computer models of the femur and bone tunnels were reconstructed from computed tomography images obtained 3 weeks and 1 year postoperatively. The cross-sectional area at the aperture as well as inside the tunnel was compared between the two periods. Likewise, the location of tunnel walls and center in the tunnel footprint were evaluated.

RESULTS

The cross-sectional area enlarged by 22.7 % for anteromedial/intermediate graft (P = 0.002) and 28.6 % for posterolateral graft (P = 0.002) at the aperture, while decreased by 36.2 % at 10 mm from the aperture for anteromedial/intermediate graft (P = 0.004). Both the anterior and posterior walls shifted anteriorly, while the distal wall shifted distally in both tunnels. Consequently, the center in the footprint significantly shifted anteriorly (4.9-6.6 %) and distally (2.2-2.6 %) in both tunnels.

CONCLUSIONS

The femoral tunnel enlargement occurred at the aperture after ATB ACL reconstruction, but did not occur in the middle of the femoral tunnel. The morphology at the aperture changed with time after surgery as the tunnel walls translated anteriorly and distally.

LEVEL OF EVIDENCE

Case series, Level IV.

Evaluating the distance between the femoral tunnel centers in anatomic double-bundle anterior cruciate ligament reconstruction using a computer simulation

Purpose

We aimed to clarify the distance between the anteromedial (AM) bundle and posterolateral (PL) bundle tunnel-aperture centers by simulating the anatomical femoral tunnel placement during double-bundle anterior cruciate ligament reconstruction using 3-D computer-aided design models of the knee, in order to discuss the risk of tunnel overlap. Relationships between the AM to PL center distance, body height, and sex difference were also analyzed.

Patients and methods

The positions of the AM and PL tunnel centers were defined based on previous studies using the quadrant method, and were superimposed anatomically onto the 3-D computer-aided design knee models from 68 intact femurs. The distance between the tunnel centers was measured using the 3-D DICOM software package. The correlation between the AM–PL distance and the subject’s body height was assessed, and a cutoff height value for a higher risk of overlap of the AM and PL tunnel apertures was identified.

Results

The distance between the AM and PL centers was 10.2±0.6 mm in males and 9.4±0.5 mm in females (P<0.01). The AM–PL center distance demonstrated good correlation with body height in both males (r=0.66, P<0.01) and females (r=0.63, P<0.01). When 9 mm was defined as the critical distance between the tunnel centers to preserve a 2 mm bony bridge between the two tunnels, the cutoff value was calculated to be a height of 160 cm in males and 155 cm in females.

Conclusion

When AM and PL tunnels were placed anatomically in simulated double-bundle anterior cruciate ligament reconstruction, the distance between the two tunnel centers showed a strong positive correlation with body height. In cases with relatively short stature, the AM and PL tunnel apertures are considered to be at a higher risk of overlap when surgeons choose the double-bundle technique.

An in Vivo 3D Computed Tomographic Analysis of Femoral Tunnel Geometry and Aperture Morphology Between Rigid and Flexible Systems in Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique

PURPOSE

The aim of this study was to compare femoral tunnel length, femoral graft-bending angle, posterior wall breakage, and femoral aperture morphologic characteristics between rigid and flexible systems after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using the transportal (TP) technique.

METHODS

We evaluated 3-dimensional computed tomography (3D-CT) results for 54 patients who underwent DB ACL reconstruction using the TP technique with either a flexible system (n = 27) or a rigid system (n = 27). The femoral tunnel length, femoral graft-bending angle, posterior wall breakage, femoral tunnel aperture height to width (H:W) ratio, aperture axis angle, and femoral tunnel position were assessed using OsiriX Imaging Software and Geomagic Qualify 2012 (Geomagic, Cary, NC).

RESULTS

The mean anteromedial (AM) femoral tunnel length of the flexible group was significantly longer than that of the rigid group (P = .009). The mean femoral graft-bending angles in the flexible group were significantly less acute than those in the rigid group (AM, P < .001; posterolateral [PL], P = .003]. Posterior wall breakage was observed in both groups (P = 1.00). The mean H:W ratios in the rigid group were significantly larger (more elliptical) than those of the flexible group (AM, P < .001; PL, P = .006). The mean aperture axis angle of the PL femoral tunnel in the rigid group was more parallel to the femoral shaft axis than that in the flexible group (P < .001). There were no significant differences in femoral tunnel position between the 2 groups.

CONCLUSIONS

The AM femoral tunnel length and the AM/PL femoral graft-bending angle of the flexible system were significantly longer and less acute than those of the rigid system. However, the aperture morphologic characteristics of the AM/PL femoral tunnel and the aperture axis angle of the PL femoral tunnel in the rigid system were significantly more elliptical and closer to parallel to the femoral shaft axis than those of the flexible system.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Eccentric graft positioning within the femoral tunnel aperture in anatomic double-bundle anterior cruciate ligament reconstruction using the transportal and outside-in techniques

BACKGROUND

Ellipticity of the femoral tunnel aperture, which is considered to better restore the native anterior cruciate ligament (ACL) footprint after ACL reconstruction, is different according to the femoral tunneling technique used. How much of the femoral tunnel aperture is filled with graft in different tunneling techniques has yet to be evaluated.

PURPOSE

The aim of this study was to evaluate and compare the graft filling area and graft position within the femoral tunnel aperture in ACL reconstruction using the transportal (TP) and outside-in (OI) techniques.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 70 patients were randomized to undergo double-bundle ACL reconstruction using either the TP (n=35) or OI (n=35) technique. The aperture filling was evaluated by calculating the ratio of the cross-sectional area of the graft to that of the femoral tunnel, and the graft center position within the tunnel was assessed using immediate postoperative magnetic resonance imaging.

RESULTS

The cross-sectional area of the femoral anteromedial (AM) tunnel aperture in the TP group (605.5±112.7 mm2) was larger than that in the OI group (537.9±126.8 mm2). The cross-sectional area of the femoral posterolateral (PL) tunnel aperture in the TP group (369.9±88.3 mm2) did not differ significantly from that of the OI group (387.9±87.0 mm2). The grafts filled only 52.0% of the AM tunnel and 55.3% of the PL tunnel in the TP group, compared with 54.9% of the AM tunnel and 54.4% of the PL tunnel in the OI group, but there was no statistically significant difference (P>.05). The AM graft center was positioned 1.7±0.6 mm from the center of the tunnel aperture in the TP group and 1.6±0.5 mm in the OI group, and the PL graft center was positioned 1.4±0.4 mm from the center in the TP group and 1.3±0.4 mm in the OI group, with no significant intergroup differences (P=.406 and P=.629, respectively). In the OI group, the PL graft center was positioned more perpendicular to the Blumensaat line in relation to the tunnel aperture center (-10.8°±7.6°) compared with the TP group (-4.0°±11.8°) (P=.04).

CONCLUSION

The grafts did not fill the tunnel aperture area in either group, and the centers of the grafts differed slightly from the centers of the tunnel apertures. The finding of eccentric graft positioning in the tunnel with condensation in a particular direction in each technique might suggest the necessity of an underreamed femoral tunnel for graft. In addition, it may be useful to standardize the starting position of the femoral tunnel according to anatomic landmarks.

Anatomic single-bundle anterior cruciate ligament reconstruction using the outside-in femoral tunnel drilling technique: a prospective study and short- to mid-term results

INTRODUCTION

Anatomic positioning of the femoral and tibial tunnels in the native ACL femoral and tibial footprints requires an independent drilling either via an accessory medial portal (trans-portal drilling) or using an outside-in drilling technique. Conventional trans-tibial drilling (dependant drilling) was found to lack the ability to accurately position the femoral tunnel in the native ACL footprint. The purpose of the current study was to evaluate the functional outcome results of anatomic single-bundle ACLR using the OI femoral tunnel drilling technique.

MATERIALS AND METHODS

Single surgeon single center prospective case series study. 64 patients having complete ACL tears were included in the current study. Average follow-up was 15.8 months (range 8-25). Objective and subjective IKDC scores, Lysholm knee score, SF-36 score, VAS for patients' satisfaction, VAS for pain and Kellgren and Lawrence (K/L) classification of osteoarthritis were used for follow-up evaluation.

RESULTS

Objective IKDC score revealed that 60 patients had grade ''A'' and 4 had grade ''B'', while no single patient had neither grade ''C'' nor ''D''. The average Lysholm Score was 92.4, average subjective IKDC was 91.5. Average SF-36 score was 96.7. The average VAS for operation satisfaction was 9.7. Average VAS for pain was 0.3. Forty-nine patients were classified as normal K/L classification, 7 were grade ''1'', 8 were grade ''2''. Comparing pre-operative and follow-up Objective IKDC, Subjective IKDC, Lysholm, SF-36 and VAS for pain scores revealed statistically significant differences (P value <0.05).

CONCLUSION

Arthroscopic-assisted ACL reconstruction using the outside-in femoral tunnel drilling technique shows a good and satisfactory functional outcome results at short- to mid-term follow-up.

LEVEL OF EVIDENCE

Level IV.

Comparison of femoral tunnel geometry, using in vivo 3-dimensional computed tomography, during transportal and outside-in single-bundle anterior cruciate ligament reconstruction techniques

PURPOSE

To compare the transportal (TP) and outside-in (OI) techniques regarding femoral tunnel position and geometry after anatomic single-bundle (SB) anterior cruciate ligament (ACL) reconstruction.

METHODS

This study included 51 patients who underwent anatomic SB ACL reconstruction with the TP (n = 21) or OI (n = 30) technique. All patients underwent 3-dimensional computed tomography 3 days after the operation. The femoral tunnel position (quadrant method), femoral graft bending angle, femoral tunnel length, and posterior wall breakage were assessed by immediate postoperative 3-dimensional computed tomography with OsiriX imaging software.

RESULTS

The OI technique had a shallower femoral tunnel position (arthroscopic position) than did the TP technique (P = .005). The mean femoral graft bending angle was significantly more acute with the OI technique (101.3° ± 8.2°) than with the TP technique (107.9° ± 10.0°) (P = .02). The mean femoral tunnel length was significantly greater with the OI technique (33.0 ± 3.5 mm) than with the TP technique (29.6 ± 3.9 mm) (P = .003). Posterior wall breakage occurred in 7 cases (33.3%) with the TP technique and 1 case (3.3%) with the OI technique (P = .02).

CONCLUSIONS

The mean femoral tunnel position was significantly shallower (arthroscopic position) with the OI technique than with the TP technique. The OI technique resulted in a more acute femoral graft bending angle, longer femoral tunnel length, and lower incidence of posterior wall breakage than did the TP technique. These results might be helpful for anatomic SB ACL reconstruction using TP and OI techniques.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.