Oblique femoral tunnel placement can increase risks of short femoral tunnel and cross-pin protrusion in anterior cruciate ligament reconstruction

Robot-assisted anterior cruciate ligament reconstruction based on three-dimensional images

Background Tunnel placement is a key step in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the accuracy of bone tunnel drilling in arthroscopic ACL reconstruction assisted by a three-dimensional (3D) image-based robot system. Methods Robot-assisted ACL reconstruction was performed on twelve freshly frozen knee specimens. During the operation, three-dimensional images were used for ACL bone tunnel planning, and the robotic arm was used for navigation and drilling. Twelve patients who underwent traditional arthroscopic ACL reconstruction were included. 3D computed tomography was used to measure the actual position of the ACL bone tunnel and to evaluate the accuracy of the robotic and traditional ACL bone tunnel. Results On the femoral side, the positions of robotic and traditional surgery tunnels were 29.3 ± 1.4% and 32.1 ± 3.9% in the deep-to-shallow direction of the lateral femoral condyle (p = 0.032), and 34.6 ± 1.2% and 21.2 ± 9.4% in the high-to-low direction (p < 0.001), respectively. On the tibial side, the positions of the robotic and traditional surgical tunnels were located at 48.4 ± 0.9% and 45.8 ± 2.8% of the medial-to-lateral diameter of the tibial plateau (p = 0.008), 38.1 ± 0.8% and 34.6 ± 6.0% of the anterior-to-posterior diameter (p = 0.071), respectively. Conclusions In this study, ACL reconstruction was completed with the assistance of a robot arm and 3D images, and the robot was able to drill the bone tunnel more accurately than the traditional arthroscopic ACL reconstruction.

A Novel Predictor of the Length and Size of ACL Grafts in Chinese Han Adults for ACL Reconstruction: An MRI Study

OBJECTIVE

Currently, there is no simple and valid method to predict the length and size of the native anterior cruciate ligament (ACL) in each adult patient who will undergo ACL reconstruction. This study aimed to develop an imaging prediction method that can predict the length and size of ACL grafts using the intact posterior cruciate ligament (PCL), in order to enhance the graft preparation individualized sizing.

METHODS

Three hundred and nineteen patients aged 18 years or older who underwent magnetic resonance imaging (MRI) of the knee at an orthopaedic clinic between September 9, 2021, and February 5, 2023, were included. The length, sagittal diameter, and coronal diameter of the ACL and PCL were measured in all patients, and F-test were performed to explore linear relationship between ligament measurements.

RESULTS

Equations were established to predict a variable of the native ACL for the corresponding variable of the intact PCL (i.e., sagittal diameter of the ACL = 4.32 + 1.08 × sagittal diameter of the PCL, and coronal diameter of the ACL = 2.45 + 0.59 × coronal diameter of the PCL, length of the male ACL = 10.92 + 0.64 × length of the male PCL, length of the female ACL = 11.76 + 0.58 × length of the female PCL) (R2  = 0.532; R2  = 0.417; R2  = 0.488; R2  = 0.509; respectively).

CONCLUSIONS

The length and size of the intact PCL in cases without PCL buckling are predictors of the length and size of the native ACL in adults, respectively. The use of this information to optimize graft diameter may lower the rates of ACL graft failure in the future.

Research progress on preparation of lateral femoral tunnel and graft fixation in anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) injury is one of the most common types of sports injuries. People's need to participate in sports and desire for a high quality of life promotes the continuous development of ACL reconstruction technology. Arthroscopic ACL reconstruction has been recognized as an effective method for the treatment of ACL injuries. This review analyses and summarizes the advantages and limitations of each surgical procedure for arthroscopic ACL reconstruction reported in the relevant literature so as to promote the future development of more relevant techniques.

Freehand vs. Medial Portal Offset Aimer Technique for Accurate Femoral Tunnel Placement in Arthroscopic ACL Reconstruction

Purpose

In this study, our aim was to reveal the effect of the medial femoral offset aimer usage through the femoral tunnel entry and exit points and the tunnel length during femoral tunnel drilling in arthroscopic anterior cruciate ligament (ACL) reconstruction.

Methods

One hundred patients who underwent arthroscopic single-bundle ACL reconstruction were included in the study. Group 1 consisted of 50 patients who underwent femoral tunnel drilling using a medial portal offset aimer device, while Group 2 consisted of 50 patients who were operated on using the freehand technique. Both groups were compared in terms of femoral tunnel and graft tunnel lengths, femoral tunnel angle in the coronal plane, and the location of the femoral tunnel entry and exit points.

Results

The mean femoral tunnel and graft tunnel lengths were significantly longer in Group 2 (p = 0.000). There was no significant difference in terms of localization of the femoral tunnel entry point in both the axial and sagittal planes. The tunnel exit point was located significantly more posterior in Group 1 in the axial plane (p = 0.028). There was no significant difference in terms of the coronal plane femoral tunnel angle between the two groups.

Conclusion

In arthroscopic ACL reconstructions, more successful results may be obtained with the freehand technique compared to drilling with a femoral offset aimer. For an experienced orthopedic surgeon, using a medial portal offset aimer device during femoral tunnel drilling does not seem necessary.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-023-00929-z.

Influence of the Anteromedial Portal and Transtibial Drilling Technique on Femoral Tunnel Lengths in ACL Reconstruction: Results Using an MRI-Based Model

Background:

In anatomic anterior cruciate ligament (ACL) reconstruction, graft placement through the anteromedial (AM) portal technique requires more horizontal drilling of the femoral tunnel as compared with the transtibial (TT) technique, which may lead to a shorter femoral tunnel and affect graft-to-bone healing. The effect of coronal and sagittal femoral tunnel obliquity angle on femoral tunnel length has not been investigated.

Purpose:

To compare the length of the femoral tunnels created with the TT technique versus the AM portal technique at different coronal and sagittal obliquity angles using the native femoral ACL center as the starting point of the femoral tunnel. The authors also assessed sex-based differences in tunnel lengths.

Study Design:

Descriptive laboratory study.

Methods:

Magnetic resonance imaging scans of 95 knees with an ACL rupture (55 men, 40 women; mean age, 26 years [range, 16-45 years]) were used to create 3-dimensional models of the femur. The femoral tunnel was simulated on each model using the TT and AM portal techniques; for the latter, several coronal and sagittal obliquity angles were simulated (coronal, 30°, 45°, and 60°; sagittal, 45° and 60°), representing the 10:00, 10:30, and 11:00 clockface positions for the right knee. The length of the femoral tunnel was compared between the techniques and between male and female patients.

Results:

The mean ± SD femoral tunnel length with the TT technique was 40.0 ± 6.8 mm. A significantly shorter tunnel was created with the AM portal technique at 30° coronal/45° sagittal (35.5 ± 3.8 mm), whereas a longer tunnel was created at 60° coronal/60° sagittal (53.3 ± 5.3 mm; P < .05 for both). The femoral tunnel created with the AM portal technique at 45° coronal/45° sagittal (40.7 ± 4.8 mm) created a similar tunnel length as the TT technique. For all techniques, the femoral tunnel was significantly shorter in female patients than male patients.

Conclusion:

The coronal and sagittal obliquity angles of the femoral tunnel in ACL reconstruction can significantly affect its length. The femoral tunnel created with the AM portal technique at 45° coronal/45° sagittal was similar to that created with the TT technique.

Clinical Relevance:

Surgeons should be aware of the femoral tunnel shortening with lower coronal obliquity angles, especially in female patients.

Safe femoral condyle range for the reverse Rigidfix femoral fixation device in anterior cruciate ligament reconstruction

Background

To determine the characteristics of cross-pin protrusion in patients treated with the reverse Rigidfix femoral fixation device for femoral tunnel preparation through the anteromedial portal in Arthroscopic anterior cruciate ligament reconstruction (ACLR), analyse the reasons for this outcome, and identify safety hazards of this surgical technique for improvement.

Methods

A retrospective analysis of patients who underwent ACLR using this technology at our hospital in 2018 was conducted. Patients with and without cross-pin protrusion were included in the protrusion positive and negative groups, respectively. The sex, age and imaging characteristics of the patients with cross-pin protrusion were identified, and the reasons for cross-pin protrusion were analysed.

Results

There were 64 and 212 patients in the protrusion positive and negative groups, respectively. The proportion of cross-pin protrusion cases was 23.19% (64/276). There was a significant difference in the ratio of males to females (P < 0.001, χ2 = 185.184), the mediolateral femoral condyle diameter (protrusion positive group, 70.59 ± 2.51 mm; protrusion negative group, 82.65 ± 4.16 mm; P < 0.001, t = 28.424), and the anteroposterior diameter of the lateral femoral condyle (protrusion positive group, 58.34 ± 2.89 mm; protrusion negative group, 66.38 ± 3.53 mm; P < 0.001, t = 16.615). The cross-pins did not penetrate the lateral femoral condyle cortex in patients with a mediolateral femoral condyle diameter ≥ 76 mm, but the cross-pins definitely penetrated the cortex when the diameter was ≤ 70 mm. The cross-pins did not penetrate when the anteroposterior lateral femoral condyle diameter was ≥ 66 mm, but the cross-pins definitely penetrated it when the diameter was ≤ 59 mm.

Conclusion

The patients with cross-pin protrusion after reverse Rigidfix femoral fixation treatment to prepare the femoral tunnel through the anteromedial portal in ACLR were mainly females with small femoral condyles. For patients with a mediolateral femoral condyle diameter ≥ 76 mm and an anteroposterior lateral femoral condyle diameter ≥ 66 mm, there is no risk of cross-pin protrusion, so this technique can be used with confidence.

Levels of evidence

III.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05250-8.

Flexible Versus Rigid Reaming Systems for Independent Femoral Tunnel Reaming During ACL Reconstruction: Minimum 2-Year Clinical Outcomes

Background:

Radiographic and cadaveric studies have suggested that anatomic anterior cruciate ligament reconstruction (ACLR) femoral tunnel drilling with the use of a flexible reaming system through an anteromedial portal (AM-FR) may result in a different graft and femoral tunnel position compared with using a rigid reamer through an accessory anteromedial portal with hyperflexion (AAM-RR). No prior studies have directly compared clinical outcomes between the use of these 2 techniques for femoral tunnel creation during ACLR.

Purpose:

To compare revision rates at a minimum of 2 years postoperatively for patients who underwent ACLR with AM-FR versus AAM-RR. The secondary objectives were to compare functional testing and patient-reported outcomes between the cohorts.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were consecutive patients at a single academic institution between 2013 and 2018 who underwent primary ACLR without additional ligamentous reconstruction. Patients were separated into 2 groups based on the type of anatomic femoral tunnel drilling: AM-FR or AAM-RR. Graft failure, determined by revision ACLR, was assessed with a minimum 2 years of postoperative follow-up. The authors also compared patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]) and functional performance testing performed at 6 months postoperatively.

Results:

A total of 284 (AAM-RR, 232; AM-FR, 52) patients were included. The mean follow-up time was 3.7 ± 1.5 years, with a minimum 2-year follow-up rate of 90%. There was no significant difference in the rate of revision ACLR between the AAM-RR and AM-FR groups (10.8% vs 9.6%, respectively; P = .806). At 6 months postoperatively, there were no significant between-group differences in peak knee extension strength, peak knee flexion strength, limb symmetry indices, or hop testing, as well as no significant differences in IKDC (AAM-RR, 81.1; AM-FR, 78.9; P = .269) or KOOS (AAM-RR, 89.0; AM-FR, 86.7; P = .104).

Conclusion:

In this limited study, independent femoral tunnel drilling for ACLR using rigid or flexible reaming systems resulted in comparable rates of revision ACLR at a minimum of 2 years postoperatively, with no significant differences in strength assessments or patient-reported outcomes at 6 months postoperatively.

Effects of flexible reamer on the femoral tunnel characteristics in anterior cruciate ligament reconstruction

To compare the femoral tunnel characteristics using a rigid versus flexible reamer during anterior cruciate ligament reconstruction. It was hypothesized that the employment of a flexible reamer along with femoral tunnel would exhibit longer tunnel length and more acute femoral graft tunnel angle compared to the case of a rigid reamer.The study population included 28 patients who underwent anatomical single-bundle anterior cruciate ligament reconstruction using transportal technique and were able to take postoperative computed tomography (CT) evaluation. Of these, the femoral tunnel of 14 cases was drilled with a flexible reamer (group I) and in another 14 cases drill was performed with a conventional rigid reamer (group II). The femoral tunnel in group I was made at 90° of knee flexion. In group II, the femoral tunnel was created at 120° of knee flexion. The parameters of the femoral tunnels were compared in terms of the femoral tunnel length and femoral graft tunnel angle. Special software was used to create and manipulate (3-D) 3-dimensional knee models.The difference in the mean femoral tunnel locations expressed in percentage distance between the 2 groups was not significantly different. The mean femoral tunnel length of group I was significantly longer than that of group II, (P = .03, 36.7 ± 2.9 vs 32.9 ± 9.0 mm). The angle formed by the femoral tunnel and the graft in group I was significantly smaller than in group II (P = .01, 109.8° ± 9.4° vs 118.1° ± 7.2°).Our data suggest that the flexible reamer can provide sufficient tunnel length for the suspensory fixation with a fixed loop. Whereas, the femoral graft-tunnel angle through flexible reaming at 90° of knee flexion was more acute compared to rigid reaming at 120° of knee flexion.Study Design: level of evidence III.

Comparing the Use of Flexible and Rigid Reaming Systems Through an Anteromedial Portal for Femoral Tunnel Creation During Anterior Cruciate Ligament Reconstruction: A Systematic Review

Background

Recent studies have suggested that femoral tunnel drilling during anterior cruciate ligament (ACL) reconstruction (ACLR) with the use of a flexible reaming system through a standard anteromedial portal (AM-FR) may result in a different tunnel geometry compared with a rigid reamer through an accessory anteromedial portal with hyperflexion (AM-RR).

Purpose

To summarize radiologic, anatomic, and clinical outcomes from available studies that directly compared the use of AM-FR versus AM-RR for independent femoral tunnel creation during ACLR.

Study Design

Systematic review; Level of evidence, 4.

Methods

A literature search was performed using the MEDLINE (PubMed) and Web of Science databases to identify all studies that directly compared radiologic, anatomic, and clinical outcomes between the use of AM-FR and AM-RR. The literature search, data recording, and methodological quality assessment was performed by 2 independent reviewers. The outcomes analyzed included resultant ACL graft positioning and graft bending angle; femoral tunnel positioning, aperture morphology, length, and widening; posterior wall breakage; and distance from various posterolateral knee structures.

Results

A total of 13 studies met the eligibility criteria for inclusion. There was no difference in femoral tunnel aperture location between techniques. There were conflicting findings among studies regarding which technique resulted in a more acute graft bending angle. One study reported greater femoral tunnel widening upon follow-up with the use of AM-FR. AM-FR produced longer and more anteverted femoral tunnels than did AM-RR. The difference in tunnel length was significant and more prominent in lesser degrees of knee flexion. With AM-FR, femoral tunnels were farther from the lateral collateral ligament and peroneal nerve, and 1 of 5 studies had fewer reports of posterior wall breakage. There has been no literature comparing the clinical or functional outcomes of these techniques.

Conclusion

Although no clinical studies exist comparing AM-FR and AM-RR for femoral tunnel creation during ACLR, both systems allow for reproducible positioning of an anatomic femoral tunnel aperture. The use of AM-FR results in longer and more anteverted femoral tunnels than using AM-RR, with exit points on the lateral femur that are different but safe. Surgeons should be aware of the technical differences with each method; however, further study is needed to identify any clinically important difference that results.

Anterior cruciate ligament femoral-tunnel drilling through an anteromedial portal: 3-dimensional plane drilling angle affects tunnel length relative to notchplasty

Background

Notchplasty is a surgical technique often performed during anterior cruciate ligament reconstruction (ACLR) with widening of the intercondylar notch of the lateral distal femur to avoid graft impingement. The purpose of this study was to correlate femoral-tunnel length with 3-dimensional (3D) drilling angle through the anteromedial (AM) portal with and without notchplasty.

Materials and methods

Computer data were collected from an anatomical study using 16 cadaveric knees. The anterior cruciate ligament (ACL) femoral insertion was dissected and outlined for gross anatomical observation. The dissected cadaveric knees were scanned by computed tomography (CT). Three-dimensional measurements were calculated using software (Geomagic, Inc., Research Triangle Park, NC, USA) and included the center of the ACL footprint and the size of the ACL femoral footprint. The femoral-tunnel aperture centers were measured in the anatomical posterior-to-anterior and proximal-to-distal directions using Bernard’s quadrant method. The ACL tunnel was created 3-demensionally in the anatomical center of femoral foot print of ACL using software (SolidWorks®, Corp., Waltham, MA, USA). The 8-mm cylinder shaped ACL tunnel was rested upon the anatomical center of the ACL footprint and placed in three different positions: the coronal plane, the sagittal plane, and the axial plane. Finally, the effect of notchplasty on the femoral-tunnel length and center of the ACL footprint were measured. All the above-mentioned studies performed ACLR using the AM portal.

Results

The length of the femoral tunnels produced using the low coronal and high axial angles with 5-mm notchplasty became significantly shorter as the femoral starting position became more horizontal. The result was 30.38 ± 2.11 mm on average at 20° in the coronal plane/70° in the axial plane/45° in the sagittal plane and 31.26 ± 2.08 mm at 30° in the coronal plane/60° in the axial plane/45° in the sagittal plane, respectively, comparing the standard technique of 45° in the coronal/45° in the axial/45° in the sagittal plane of 32.98 ± 3.04 mm (P < 0.001). The tunnels made using the high coronal and low axial angles with notchplasty became longer than those made using the standard technique: 40.31 ± 3.36 mm at 60° in the coronal plane/30° in the axial plane/45° in the sagittal plane and 50.46 ± 3.13 mm at 75° in the coronal plane/15° in the axial plane/45° in the sagittal plane (P < 0.001).

Conclusions

Our results show that excessive notchplasty causes the femoral tunnel to be located in the non-anatomical center of the ACL footprint and reduces the femoral-tunnel length. Therefore, care should be taken to avoid excessive notchplasty when performing this operation.

Femoral tunnel length has no correlation with graft rupture: A retrospective cohort study

BACKGROUND

Literature is controversial on femoral tunnel length as a risk factor for graft injury if the graft length in the tunnel is kept constant at ≥15 mm.

METHODS

A total of 1079 sportspersons, meeting our inclusion criteria, were assessed for graft rupture. Patients with femoral tunnel length (FTL) ≤30 mm were labeled as Group 1, while those with FTL > 30 mm were labeled as Group 2. Both groups were compared for potential risk factors for graft injury keeping graft length in the tunnel at ≥15 mm and statistical analysis was performed to study whether the femoral tunnel length acted as an additional risk factor.

RESULTS

Of 1079 sportspersons, 37 suffered from graft rupture. Patients with FTL > 30 mm were included in Group 1(n = 22) and patients with FTL ≤ 30 mm (n = 15) were included in Group 2. Both groups were comparable for risk factors for ACL injury: age (P = 0.37), gender (P = 0.53), mode of re-injury (P = 0.38), graft diameter (P = 0.71), level of sports activity (P = not significant), duration from injury to index surgery (P = 0.74), duration from index surgery to re-injury (P = 0.52), timing of return to sports after index surgery (P = 0.30), duration of sporting activity before second injury (P = 0.31), Tegner's level (P = not siginificant), Notch width index (P = 0.12) posterior slope (P = 0.77) and height (P = 0.41).

CONCLUSION

Because the graft length in the tunnel was kept at optimum and the risk factors for ACL injury were comparable in both groups at a follow up period, we suggest that femoral tunnel length is not a risk factor for graft failure.

Comparison of clinical results of anteromedial and transtibial femoral tunnel drilling in ACL reconstruction

BACKGROUND

A femoral bone tunnel in ACL reconstruction can be constructed from the outside in or from the inside out. When doing it inside out, the approach can be via the anteromedial (AM) portal or through the tibial bone tunnel. It has been suggested that better results might be expected by doing it anteromedially. Clinical results after femoral tunnel drilling via the AM or transtibial (TT) techniques in reconstruction of anterior cruciate ligament (ACL) are presented.

METHODS

Three hundred patients with ACL injuries were chosen for this study from previously collected data on ACL reconstructions. They were divided into two groups: 150 patients treated with AM drilling and 150 treated with TT drilling. In the AM group, the reconstructions were performed using a semitendinosus graft with the Tape Locking Screw (TLS™) technique (n = 87) or Retrobutton™ femoral and BioScrew™ tibial fixation with a semitendinosus-gracilis graft (n = 63). In the TT group, the fixation method used was Rigidfix™ femoral and Intrafix tibial fixation with a semitendinosus-gracilis graft. The evaluation methods were clinical examination, knee scores (Lysholm, Tegner and IKDC) and instrumented laxity measurements (KT-2000™). Our aim was to evaluate if there was better rotational stability and therefore better clinical results when using AM drilling compared to TT drilling.

RESULTS

After excluding revision ACL reconstructions, there were 132 patients in the AM group and 133 in the TT group for evaluation. At the 2-year follow-up, there were 60 patients in the AM group (45.5%) and 58 in the TT group (43.6%). There were no statistically significant differences between the groups in any of the evaluation methods used.

CONCLUSION

Both drilling techniques resulted in improved patient performance and satisfaction. We found no data supporting the hypothesis that the AM drilling technique provides better rotational stability to the knee.

TRIAL REGISTRATION

ISRCTN registry with study ID ISRCTN16407730. Retrospectively registered Jan 9th 2020.

Assessment of fixation for anterior cruciate ligament reconstruction using oversized suspensory devices on full-length femoral tunnels

BACKGROUND

In ACL repair, full-length single-diameter tunnels facilitate anatomic femoral fixation with suspensory devices, especially with outside-in techniques, and are required after accidental cortical perforation. With tunnel diameters over 6 mm, fixation resistance using regular suspensory devices may not suffice. Oversized cortical footprint devices could be a solution to guarantee fixation performance in larger tunnel diameters. This study aims to assess the biomechanical properties of ACL femoral fixation provided by two enlarged suspensory devices of similar characteristics, a fixed loop (G-Lok™ with G-Lok-XL™) and an adjustable loop (ProCinch™ with G-Lok-XL™), resting on a full-length 9 mm diameter tunnel compared to the widely accepted regular fixed-loop device (G-Lok™) on a socket tunnel.

METHODS

Twenty-seven fresh frozen porcine femurs and flexor digitorum profundus tendons were randomly assigned to a study group depending on the fixation method used (N = 9). Graft-femur constructs were subjected to a traction cyclic test (5000 cycles, [50-250]N load, 1 Hz) followed by a load-to-failure test (v = 1 mm/s). Residual displacement during the cyclic test and stiffness, displacements at physiological loads, ultimate load and corresponding displacement during the load-to-failure test were determined.

FINDINGS

No significant differences could be established for any parameter measured in the comparison between the control with the socket tunnel and the oversized fixations with full-length tunnels.

INTERPRETATION

ACL femoral fixation achieved in full-length single diameter tunnels by using an enlarged suspension device, both with a fixed or an adjustable loop, provide similar biomechanical properties to the gold-standard fixed-loop device in a socket tunnel. Therefore, its clinical use may be safe.

Comparison of femoral tunnel length and obliquity of anatomic versus nonanatomic anterior cruciate ligament reconstruction: A meta-analysis

Purpose

Theoretical considerations suggest that femoral tunnel length might cause graft mismatch, and femoral tunnel obliquity could be related to the longevity of graft in anterior cruciate ligament (ACL) reconstruction. However, controversy still exists regarding these issues in the context of the comparison of anatomic and nonanatomic ACL reconstructions. The purpose of this meta-analysis was to compare the length and obliquity of the femoral tunnel created by drilling through either anatomic or nonanatomic ACL reconstructions.

Materials and method

In this meta-analysis, we reviewed studies that compared femoral tunnel length and femoral tunnel obliquity in the coronal plane with the use of anatomic or nonanatomic ACL reconstruction. The major databases were reviewed for appropriate studies from the earliest available date of indexing through December 31, 2018. No restrictions were placed on the language of publication.

Results

Twenty-seven studies met the criteria for inclusion in this meta-analysis. The femur tunnel length of anatomic ACL reconstruction was significantly shorter compared with that of nonanatomic ACL reconstruction by 8.66 mm (95% CI: 7.10–10.22 mm; P<0.001), while the femur tunnel obliquity in the coronal plane of anatomic ACL reconstruction was significantly more oblique versus that of nonanatomic ACL reconstruction by 15.29° (95% CI: 8.07°–22.52°; P<0.001). Similar results in terms of femoral tunnel length were found for the subgroup with cadaveric (7.15 mm; 95% CI: 2.69–11.61 mm; P = 0.002) and noncadaveric (8.96 mm; 95% CI: 7.24–10.69 mm; P<0.001) studies, whereas different results in terms of femoral tunnel obliquity were noted for the subgroup with cadaveric (10.62°; 95% CI: −6.12° to 27.37°; P = 0.21) and noncadaveric (15.86°; 95% CI: 8.11°–23.60°; P<0.001) studies.

Conclusion

Anatomic ACL reconstruction resulted in the femoral tunnel length and femoral tunnel obliquity in the coronal plane being shorter and more oblique, respectively, as compared with nonanatomic ACL reconstruction.

Level of evidence

Therapeutic study, Level III.

Anteromedial Portal Drilling Yielded Better Survivorship of Anterior Cruciate Ligament Reconstructions When Comparing Recent Versus Early Surgeries With This Technique

PURPOSE

To compare anteromedial (AM) and transtibial (TT) femoral drilling hole techniques in primary anterior cruciate ligament reconstruction, using the Danish Knee Ligament Reconstruction Register, comparing revision rates and clinical outcomes from 2 time periods, 2007 to 2010 and 2012 to 2015.

METHODS

A total of 8,386 primary anterior cruciate ligament reconstructions were registered between January 2007 to December 2010 and 8,818 in the period January 2012 to December 2015. Revision ACL was the primary endpoint. Secondary endpoints were the objective and subjective clinical outcomes. Crude and adjusted relative risks (RRs) with 95% confidence interval (CIs) were calculated.

RESULTS

The adjusted RR for revision surgery in the AM (2007-10) group compared with the TT (2007-10) group was 1.45 (95% CI, 1.17-1.78; P < .05), but when comparing the AM (2012-15) group with TT (2012-15) group, the RR was 0.99 (95% CI, 0.68-1.45; P = .96). One-year postoperative objective stability testing showed an RR = 1.38 (95% CI, 1.19-1.60; P < .01) for rotational stability and an RR = 1.37 (95% CI, 0.99-1.89; P < .01) for sagittal stability when comparing AM (2007-10) to TT (2007-10). No significant difference in objective stability was found in the more recent period. Lastly, comparing the subjective scores, the AM (2012-15) had a significantly higher Tegner score 1 year postoperatively compared with the TT-group (2012-15).

CONCLUSIONS

This study found an increased RR of revision anterior cruciate ligament and rotational and sagittal instability 1 year postoperatively for the AM technique in the period from 2007 to 2010. However, there was no significant difference in revision surgery and objective measures between the techniques from 2012 to 2015. Nevertheless, a higher activity level was found in the AM group. The results could indicate that the results found in the period 2007 to 2010 may have been caused by a learning curve when introducing a new and more complex procedure (AM).

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Comparison of Modified Transtibial and Outside-In Techniques in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE

To compare the bending angle of anterior cruciate ligament (ACL) graft at femoral tunnel, graft maturation, and tunnel positions and the clinical outcomes of the modified transtibial (mTT) and outside-in (OI) techniques.

METHODS

Patients who met the inclusion criteria were divided into the mTT group (n = 50) and the OI group (n = 50). Using 3-dimensional computed tomography (3-D CT), tunnel placement and femoral tunnel bending angle were analyzed. The 3.0-T magnetic resonance imaging (MRI) was used to assess the graft signal intensity (indicative of maturation) with signal/noise quotient (SNQ). Graft tension and synovialization were evaluated with second-look arthroscopy in all cases. Clinical and functional tests were completed at 36 months of follow-up.

RESULTS

When tunnel placements were analyzed using the quadrant method, no significant differences were found between the mTT group and the OI group. The femoral graft bending angle was reduced in the mTT group, and the total mean of SNQ values and mean SNQ values at the femoral intraosseous and proximal graft of the mTT group were significantly lower than in the OI group (P < .001), respectively. The femoral graft bending angle on the coronal and axial planes showed moderate-to-strong correlation with the SNQ values at the femoral intraosseous and proximal graft. Second-look arthroscopy revealed better synovialization in the mTT group than in the OI group (P = .040), with no significant difference in graft tension between the 2 groups (P = .328).

CONCLUSIONS

Anatomic tunnel placements did not vary between the mTT group and the OI group. However, the mTT group had more benefits in femoral graft bending angle and showed higher graft maturity and better synovial coverage than the OI group, although there were no significant differences in clinical outcomes. The acute femoral graft bending angle might negatively affect the maturation of proximal graft. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Radiological evaluation of the femoral tunnel positioning in anterior cruciate ligament reconstruction

OBJECTIVE

To evaluate the inclination and the length of the femoral tunnel in patients submitted to anterior cruciate ligament reconstruction (ACL) surgery by transtibial and anatomical techniques.

METHODS

This is an analytical observational study in patients with ACL injury that underwent arthroscopic reconstruction through transtibial and anatomical surgical techniques. In the immediate postoperative period, computed tomography (CT) and anteroposterior (AP) view digital radiographs (X-rays) were performed to evaluate the inclination and length of the femoral tunnel.

RESULTS

Forty-two patients were analyzed: 27 underwent anatomical reconstruction and 15, transtibial reconstruction. The inclination angle and tunnel length by the transtibial technique are always greater than by the anatomical technique. The mean inclination angles were 59.75° (53.9-66.1°) in the X-rays and 54.17° (43.5-62.3°) in CT for the transtibial technique, and 42.91° (29.3-57.4°) in the X-rays and 39.10° (23.8-50.6°) in CT for the anatomical technique. Regarding the length of the femoral tunnel, the transtibial technique promotes longer tunnels: mean 55.7 mm (40.0-70.2 mm) in the transtibial and 35.5 mm (24.5-47 mm) in the anatomical technique. No statistically significant correlation was observed between the length and the inclination of the tunnel, regardless of the technique used. Thus, these variables can be considered as independent.

CONCLUSION

The anatomical reconstruction technique presented shorter femoral tunnels and lower angle of inclination than the transtibial technique. The CT showed smaller inclination angle than the X-rays, regardless of the surgical technique.

Drilling through anteromedial portal with a femoral aiming device ensures a sufficient length and a proper graft position, and prevents posterior wall breakage during anterior cruciate ligament reconstruction

OBJECTIVE

The aim of this study was to evaluate the characteristics of the femoral tunnel (FT) which was drilled through the AM portal by using a femoral aimer device and AP stability of the knee.

METHODS

Thirty-eight patients, with the mean age 29.6 (range: 20-43) years, were evaluated after ACL reconstruction. The mean follow-up time was 31.9 (range: 16-57) months. The FT was drilled using a femoral aimer with different offset according to the graft size measured, through the AM portal. The semitendinous and gracilis tendon autograft was used for reconstruction. The angles of FT and the exit point on the lateral condyle were measured on AP views of the knee. AP stability of the knee was measured with the KT-2000.

RESULTS

The mean angle of FT was 46.5° (± 8.4°), on the AP view. The mean distance between the exit point of FT and the most distal end of the femoral condyles was 46.7 (± 4.9) mm. The mean FT length was 36.1 (± 3.1) mm. The mean difference of anterior translation compared to the intact knee was 1.9 (± 1.6) mm. Except the three patients, with "one positive" pivot shift test, in the remaining 35 knees stability was equal to the healthy knee.

CONCLUSIONS

Femoral drilling by using a femoral aimer device through AM portal provided long enough FT for safe graft fixation and appropriate coronal plan obliquity. The exit point was far proximal from the insertion site of the popliteus tendon and lateral collateral ligament. Furthermore, the AM portal technique significantly improved AP stability of the knee.

Influence of the different anteromedial portal on femoral tunnel orientation during anatomic ACL reconstruction

Objective

The purpose of this study was to evaluate the effect of femoral tunnel orientation, drilled through the accessory anteromedial (AAM) portal or the high AM portal in anatomic anterior cruciate ligament (ACL) reconstruction.

Methods

In 16 cadaver knees, using o'clock method, centers of the ACL femoral footprint were drilled with an 8-mm reamer via an AAM portal (eight knees) or a high AM portal (eight knees). Computed tomography (CT) scans were taken of each knee. Three-dimensional (3D) models were constructed to identify the femoral tunnel orientation and to create femoral tunnel virtual cylinders for measuring tunnel angles and length.

Results

In two of the 16 specimens, we observed a posterior femoral cortex blowout (PFCB) when drilling through a high AM portal. When drilled through the high AM portal, the femoral tunnel length was significantly shorter than when using an AAM portal (30.3 ± 3.8 mm and 38.2 ± 3.1 mm, p < 0.001). The femoral tunnel length was significantly shorter in the group with PFCB compared to the group with no PFCB (25.9 ± 0.6 mm and 35.5 ± 4.5 mm, p = 0.011). The axial obliquity of the high AM portal was significantly higher than that of the AAM portal (52.2 ± 5.9° and 43.0 ± 2.3°, p = 0.003).

Conclusions

In anatomic ACL reconstruction, a mal-positioned AM portal can cause abnormal tunnel orientation, which may lead to mechanical failure during ACL reconstruction. Therefore, it is important to select accurate AM portal positioning, and possibly using an AAM portal by measuring an accurate position when drilling a femoral tunnel in anatomic ACL reconstruction.

Optimization of Anteromedial Portal Femoral Tunnel Drilling With Flexible and Straight Reamers in Anterior Cruciate Ligament Reconstruction: A Cadaveric 3-Dimensional Computed Tomography Analysis

PURPOSE

To use 3-dimensional custom CAD technology to evaluate how knee flexion angle affects femoral tunnel length and distance to the posterior wall when using curved and straight guides for drilling through the anteromedial portal (AMP).

METHODS

Six cadaveric knees were placed in an external fixator at various degrees of flexion (90°, 110°, 125°, and maximum 135° to 140°). Computed tomography scans were obtained at all flexion points for 3-dimensional point-cloud models. Using custom CAD software, surgical guides through the AMP were replicated along with virtual tunnels at each flexion angle. Distance from the posterior cortex and tunnel dimensions were collected after 8-mm and 10-mm tunnel creation.

RESULTS

At 90° of flexion, the average tunnel length down the posterior aspect of 8-mm tunnel was 25.0 mm (95% confidence interval [CI] 16.2-33.8) and 12.0 mm (95% CI 7.3-16.7) for curved and straight guides, respectively; 31.0 mm (95% CI 26.8-35.2) and 28.6 mm (95% CI 24.8-32.4) at 110°; 33.8 mm (95% CI 30.1-37.5) and 31.1 mm (95% CI 26.8-35.4) at 125°; and 35.0 mm (95% CI 34.1-35.9) and 35.5 mm (95% CI 34.2-36.8) with maximal flexion. Values between curved and straight guides are significantly different (P < .001), with straight guides breaching the posterior wall at 90° and 110° of flexion in some specimens. The average distance to the posterior wall cortex was 0.9 mm (95% CI -1.5 to 3.3) and -0.6 mm (95% CI -2.3 to 1.1) for curved and straight guides, respectively, at 90° of flexion (P = .014); 2.3 mm (95% CI -0.2 to 4.8) and -0.1 mm (95% CI -2.4 to 2.2) at 110° (P = .001); 4.4 mm (95% CI 2.8-6.0) and 3.9 mm (95% CI 1.9-5.9) at 125° (P = .299); and 6.7 mm (95% CI 6.2-7.2) and 8.3 mm (95% CI 6.1-10.5) at maximal flexion (P = .184). Posterior wall blowout was noted when using 10-mm straight guides at both 90° (2 specimens) and 110° (3 specimens). Using 10-mm curved guides posterior blowout was noted in 1 specimen at 90°. Maximum footprint coverage occurred at 110° for straight guides and 90° for curved guides.

CONCLUSIONS

When using the AMP, flexible guides and reamers result in a greater distance of the tunnel to the femoral cortex while preserving adequate tunnel length at lower knee flexion angles. To create long femoral tunnels without breaching the posterior cortex, the knee should be flexed to at least 110° for curved reamers and 125° for straight.

CLINICAL RELEVANCE

Femoral tunnel drilling through the AMP using curved and straight reamers requires different degrees of knee flexion to achieve optimal tunnel dimensions.

Comparison of tunnel variability between trans-portal and outside-in techniques in ACL reconstruction

PURPOSE

Although trans-portal and outside-in techniques are commonly used for anatomical ACL reconstruction, there is very little information on variability in tunnel placement between two techniques.

METHODS

A total of 103 patients who received ACL reconstruction using trans-portal (50 patients) and outside-in techniques (53 patients) were included in the study. The ACL tunnel location, length and graft-femoral tunnel angle were analyzed using the 3D CT knee models, and we compared the location and length of the femoral and tibial tunnels, and graft bending angle between the two techniques. The variability in each technique regarding the tunnel location, length and graft tunnel angle using the range values was also compared.

RESULTS

There were no differences in the average of femoral tunnel depth and height between the two groups. The ranges of femoral tunnel depth and height showed no difference between two groups (36 and 41 % in trans-portal technique vs. 32 and 41 % in outside-in technique). The average value and ranges of tibial tunnel location also showed similar results in two groups. The outside-in technique showed longer femoral tunnel than the trans-portal technique (34.0 vs. 36.8 mm, p = 0.001). The range of femoral tunnel was also wider in trans-portal technique than in outside-in technique. Although the outside-in technique showed significant acute graft bending angle than trans-portal technique in average values, the trans-portal technique showed wider ranges in graft bending angle than outside-in technique [ranges 73° (SD 13.6) vs. 53° (SD 10.7), respectively].

CONCLUSIONS

Although both trans-portal and outside-in techniques in ACL reconstruction can provide relatively consistent in femoral and tibial tunnel locations, trans-portal technique showed high variability in femoral tunnel length and graft bending angles than outside-in technique. Therefore, the outside-in technique in ACL reconstruction is considered as the effective method for surgeons to make more consistent femoral tunnel.

LEVEL OF EVIDENCE

III.

Arthroscopic Control for Safe and Secure Seating of Suspensory Devices for Femoral Fixation in Anterior Cruciate Ligament Reconstruction Using Three Different Techniques

Purpose

The purpose of this study was to evaluate the efficacy of our technique that allows direct visualization of seating of suspensory devices in anterior cruciate ligament (ACL) reconstruction.

Materials and Methods

Three different suspensory devices (TightRope RT, RetroButton, and EndoButton) were used in ACL reconstruction using 3 different techniques (outside-in, anteromedial [AM] portal, and transtibial techniques). Positioning of a guiding material and seating pattern of the suspensory devices were evaluated according to the surgical technique and suspensory device used.

Results

On the transtibial technique, 21 of total 26 cases (81%) of single bundle reconstructions and 22 of total 22 cases (100%) of double bundle reconstructions required superolateral capsulotomy where buttons were found in 21 of total 21 cases (100%) and 17 of 22 cases (77%), respectively. On the AM portal technique, all patients required capsulotomy and the button was found in only 18 of total 32 cases (56%) even after capsulotomy. On the outside-in technique, all patients required capsulotomy and the button was found in 86 of total 86 cases (100%).

Conclusions

Our technique for direct visualization of seating of the suspensory devices was more effective in outside-in and single bundle transtibial ACL reconstruction. However, it was less effective in double bundle transtibial and AM portal ACL reconstructions.

Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Using the Modified Transtibial Technique

We present a technique for anterior cruciate ligament (ACL) reconstruction using hamstring tendon autograft with a modified transtibial technique. Our modified transtibial technique has the advantages of the conventional transtibial technique that is familiar to surgeons and that allows the press-fit fixing and enables us to make a relatively long femoral tunnel. To make the femoral tunnel at the anatomic position, the triangular, funnel-shaped bony trough was made to slip the eccentrically positioned guide pin into the anticipated anatomic center with a free-hand technique after marking the anatomic ACL footprint using a microfracture awl through the anteromedial portal. Gradual femoral reaming was performed with knee angle changes, which reduces the chances of posterior wall blowout, increases the femoral tunnel length, and avoids breakage of guide pin at the bending point. Our modified transtibial technique is anticipated to provide a more anatomic placement of the femoral tunnel during ACL reconstruction than the previous traditional transtibial techniques.

Drill wobble - effect on femoral tunnel aperture during anterior cruciate ligament reconstruction

BACKGROUND

In anterior cruciate ligament reconstruction performed using cortical button fixation on the femur, we have observed a "wobble" effect that can occur when a cannulated femoral drill is used over a guide pin that is not securely fixed in bone. Our study assessed the effect of drill "wobble" on femoral tunnel aperture in sawbones.

METHODS

Femoral tunnels were drilled in sawbones, which had been divided in two groups of 10 each, per drilling technique. The "wobble" technique group had the smaller cortical button drill passed before drilling the graft socket with the bigger diameter femoral drill. In contrast, in the "non-wobble" technique group, the smaller cortical button drill was passed after drilling the graft socket. The aperture dimensions: antero-posterior, proximo-distal and oblique, as well as the length of each tunnel, were measured.

RESULTS

While the average dimensions of the tunnels were similar between the two techniques, there was significantly more variation in the antero-posterior measurements for the wobble technique as compared to the non-wobble technique (mean 7.3 mm, SD 0.28 mm, and mean 7.3 mm, SD 0.11 mm, respectively; Brown-Forsythe test, p 0.02).

CONCLUSION

We conclude that using the "socket first" "non-wobble" technique is a single surgical technical step surgeons can employ to decrease variability in tunnel aperture and size.

Anterior cruciate ligament - updating article

This updating article on the anterior cruciate ligament (ACL) has the aim of addressing some of the most interesting current topics in this field. Within this stratified approach, it contains the following sections: ACL remnant; anterolateral ligament and combined intra and extra-articular reconstruction; fixation devices; and ACL femoral tunnel creation techniques.

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.

Reconstruction of the anterior cruciate ligament by means of an anteromedial portal and femoral fixation using Rigidfix

Objective

To evaluate a series of patients who underwent surgery for reconstruction of the anterior cruciate ligament with flexor tendons, by means of the anteromedial transportal technique using Rigidfix for femoral fixation, and to analyze the positioning of the pins by means of tomography.

Methods

Thirty-two patients were included in the study. The clinical evaluation was done using the Lysholm, subjective IKDC and Rolimeter. All of them underwent computed tomography with 3D reconstruction in order to evaluate the entry point and positioning of the Rigidfix pins in relation to the joint cartilage of the lateral condyle of the femur.

Results

The mean Lysholm score obtained was 87.81 and the subjective IKDC was 83.72. Among the 32 patients evaluated, 43% returned to activities that were considered to be very vigorous, 9% vigorous, 37.5% moderate and 12.5% light. In 16 patients (50%), the distal entry point of the Rigidfix pin was located outside of the cartilage (extracartilage); in seven (21.87%), the distal pin injured the joint cartilage (intracartilage); and in nine (28.12%), it was at the border of the lateral condyle of the femur.

Conclusion

The patients who underwent ACL reconstruction by means of the anteromedial transportal using the Rigidfix system presented satisfactory clinical results over the length of follow-up evaluated. However, the risk of lesions of the joint cartilage from the distal Rigidfix pin needs to be taken into consideration when the technique via an anteromedial portal is used. Further studies with larger numbers of patients and longer follow-up times should be conducted for better evaluation.

Over-the-Top Anterior Cruciate Ligament Reconstruction Using Single- or Double-Strand Hamstrings Autograft

The purpose of this study is to (1) report the long-term clinical and radiographic outcomes of a nonanatomical anterior cruciate ligament (ACL) reconstruction using an over-the-top (OTT) femoral route and (2) compare single-strand (1SHG) and double-strand (2SHG) hamstrings graft reconstruction. Fifty-one consecutive patients (mean age, 29.2±3.8 years) underwent nonanatomical ACL reconstruction using OTT femoral passage. Twenty patients underwent 1SHG reconstruction and 31 underwent 2SHG reconstruction. International Knee Documentation Committee (IKDC) score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner score, and KT-1000 (Medmetric Corporation, San Diego, California) evaluation were recorded at a mean follow-up of 12.1±1.6 years. At final follow-up, radiographic evaluation was performed according to the IKDC grading system. Mean IKDC subjective score at follow-up was 76.6±21.9 in the 1SHG group and 88.9±10.0 in the 2SHG (P=.009). Average KOOS was 82.6±18.7 in the 1SHG group and 92.4±9.2 in the 2SHG group (P=.016). Objective IKDC evaluation showed a higher percentage of normal knees in the 2SHG group (P=.018). Pivot shift testing revealed a significantly higher number of normal knees in the 2SHG group (P=.001). Radiographs showed fewer degenerative changes in the 2SHG group at final follow-up in the medial (P=.01) and lateral (P=.037) compartments. Nonanatomical ACL reconstruction using the OTT technique provided satisfactory results in terms of control of both static and dynamic instability at long-term follow-up, thus preventing degenerative joint disease. The 2SHG group showed better subjective and functional outcomes with fewer degenerative changes compared with the 1SHG group at long-term follow-up.

Farmedial versus anteromedial portal drilling of the femoral tunnel in ACL reconstruction: a computed tomography analysis

INTRODUCTION

The success of ACL reconstruction is predicated on a variety of factors. Tunnel placement plays one of the most significant roles in achieving knee kinematics and function. The purposes of this study were to compare femoral tunnel position, angle, length and posterior wall blow-out after ACL reconstruction with hamstring tendons autograft through either a farmedial portal or an anteromedial portal technique.

MATERIALS AND METHODS

We evaluated 36 patients who underwent ACL reconstruction between January 2014 and July 2014 in our institute, in a prospective, randomised cohort study. All the surgical procedures were performed by a sports fellowship-trained orthopaedic surgeon with experience in both portal reaming. The operated knees were evaluated with 0.5 mm fine CT scans of 3-D CT between days 3 and 5 postoperatively.

RESULTS

According to the 3-D CT measurements, the mean femoral tunnel length was significantly longer (p < 0.05) in the FAM group compared with the AM group. The femoral bone tunnel length averaged 34.2 ± 3.6 mm versus 36.6 ± 3.0 mm (p = 0.042) in AM and the FAM groups, respectively. The femoral tunnel position, as evaluated with use of the quadrant method, was more anterior in the FAM transportal technique group, and the difference between the two groups was significant (p < 0.05).

CONCLUSION

FAM tranportal drilling of the femoral tunnel creates longer and anterior femoral tunnels with regard to the AM portal drilling techniques. Additional studies with clinical outcomes are required for the clinical relevance of these techniques and to show which one is superior.

LEVEL OF EVIDENCE

Level I, prospective randomised comparative cohort study.

The sagittal plane angle and tunnel-related complications in double-bundle anterior cruciate ligament reconstruction using the transportal technique: an in vivo imaging study

PURPOSE

To evaluate the relation between the tunnel angle in the 3 orthogonal planes, especially the sagittal plane, which can be influenced by knee flexion during drilling, and the incidence of complications from the transportal technique using in vivo imaging data.

METHODS

Fifty-one patients who underwent anatomic double-bundle anterior cruciate ligament reconstruction by the transportal technique were evaluated retrospectively. A 3-dimensional surface model was made using an axial computed tomography scan obtained after anterior cruciate ligament reconstruction. The tunnel length, posterior cortical damage, proximity between the outer orifice of the tunnel and lateral collateral ligament (LCL) origin, and medial femoral condyle cartilage damage were evaluated on a 3-dimensional computed tomography scan and 3-T magnetic resonance imaging. Correlations between those parameters and the tunnel angle in the coronal, axial, and sagittal planes were analyzed.

RESULTS

A tunnel length of less than 30 mm developed in 4 cases (8%) in the anteromedial tunnel and in 1 case (2%) in the posterolateral (PL) tunnel. Posterior cortical damage developed in 12 cases (23%). A distance from the outer orifice of the tunnel to the LCL origin of less than 3 mm occurred in 18 cases (35.2%) in the PL tunnel. Medial femoral condyle cartilage damage was detected in 3 cases (6%). A positive correlation was observed between the sagittal angle and anteromedial tunnel length (P = .002, r = 0.547). The sagittal angle in the group with posterior cortical damage was lower than that in the group with no posterior cortical damage (P = .002). A negative correlation was observed between the distance from the outer orifice of the PL tunnel to the LCL origin and the sagittal angle (P = .002, r = -0.55).

CONCLUSIONS

Drilling at a higher angle in the sagittal plane decreased the incidence of posterior cortical damage and a short anteromedial tunnel. However, drilling at a higher angle shortened the distance to the LCL origin for the PL tunnel.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

The relation between knee flexion angle and anterior cruciate ligament femoral tunnel characteristics: a cadaveric study comparing a standard and a far anteromedial portal

PURPOSE

The purpose of this study was to compare the anterior cruciate ligament (ACL) femoral tunnel characteristics between 2 common arthroscopic portals used for ACL reconstruction, a standard anteromedial portal and a far anteromedial portal.

METHODS

Seven cadaveric knees were used. A 1.25-mm Kirschner wire was drilled through the center of the ACL femoral footprint and through the distal femur from the standard anteromedial and far anteromedial portals at knee flexion angles of 100°, 120°, and 140°. No formal tunnels were drilled. Each tunnel exit point was marked with a colored pin. After all tunnels were created, the specimens were digitized with a MicroScribe device (Revware, Raleigh, NC) to measure the tunnel length; distance to the posterior femoral cortical wall (posterior cortical margin); and tunnel orientation in the sagittal, coronal, and axial planes.

RESULTS

The standard anteromedial portal resulted in a longer tunnel length, a less horizontal tunnel in the coronal plane, and a greater posterior cortical margin compared with the far anteromedial portal at all knee flexion angles. For both portal locations, the tunnel length and posterior cortical margin increased, and the tunnel position became more horizontal in the coronal plane, more anterior in the sagittal plane, and less horizontal in the transverse plane as knee flexion increased.

CONCLUSIONS

Portal position affects femoral tunnel characteristics, with results favoring the more laterally positioned standard anteromedial portal at all flexion angles. Increasing the knee flexion angle leads to a longer femoral tunnel length and posterior femoral cortical margin with either portal position.

CLINICAL RELEVANCE

Understanding how portal positioning and knee flexion angle affect femoral tunnel orientation and characteristics may lead to improved surgical outcomes after ACL reconstruction.

Effect of anteromedial portal entrance drilling angle during anterior cruciate ligament reconstruction: a three-dimensional computer simulation

PURPOSE

The object of this study was to evaluate entrance angle effects on femoral tunnel length and cartilage damage during anteromedial portal drilling using three-dimensional computer simulation.

MATERIALS AND METHODS

Data was obtained from an anatomic study performed using 16 cadaveric knees. The anterior cruciate ligament femoral insertion was dissected and the knees were scanned by computer tomography. Tunnels with different of three-dimensional entrance angles were identified using a computer simulation. The effects of different entrance angles on the femoral tunnel length and medial femoral cartilage damage were evaluated. Specifically, tunnel length and distance from the medial femoral condyle to a virtual cylinder of the femoral tunnel were measured.

RESULTS

In tunnels drilled at a coronal angle of 45°, an axial angle of 45°, and a sagittal angle of 45°, the mean femoral tunnel length was 39.5±3.7 mm and the distance between the virtual cylinder of the femoral tunnel and the medial femoral condyle was 9.4±2.6 mm. The tunnel length at a coronal angle of 30°, an axial angle of 60°, and a sagittal angle of 45°, was 34.0±2.9 mm and the distance between the virtual cylinder of the tunnel and the medial femoral condyle was 0.7±1.3 mm, which was significantly shorter than the standard angle (p<0.001).

CONCLUSION

Extremely low and high entrance angles in both of axial plane and coronal plane produced inappropriate tunnel angles, lengths and higher incidence of cartilage damage. We recommend that angles in proximity to standard angles be chosen during femoral tunnel drilling through the anteromedial portal.

Reliability and reproducibility of several methods of arthroscopic assessment of femoral tunnel position during anterior cruciate ligament reconstruction

PURPOSE

To assess interobserver and intraobserver agreement of estimating anterior cruciate ligament (ACL) femoral tunnel positioning arthroscopically using circular and linear (noncircular) estimation methods and to determine whether overlay template visual aids improve agreement.

METHODS

Standardized intraoperative pictures of femoral tunnel pilot holes (taken with a 30° arthroscope through an anterolateral portal at 90° of knee flexion with horizontal being parallel to the tibial surface) in 27 patients undergoing single-bundle ACL reconstruction were presented to 3 fellowship-trained arthroscopists on 2 separate occasions. On both viewings, each surgeon estimated the femoral tunnel pilot hole location to the nearest half-hour mark using a whole clock face and half clock face, to the nearest 15° using a whole compass and half compass, in the top or bottom half of a linear quadrant, and in the top or bottom half of a linear trisector. Evaluations were performed first without and then with an overlay template of each estimation method.

RESULTS

The average difference among reviewers was quite similar for all 4 circular methods with the use of visual aids. Without overlay template visual aids, pair-wise κ statistic values for interobserver agreement ranged from -0.14 to 0.56 for the whole clock face and from 0.16 to 0.42 for the half clock face. With overlay visual guides, interobserver agreement ranged from 0.29 to 0.63 for the whole clock face and from 0.17 to 0.66 for the half clock face. The quadrant method's interobserver agreement ranged from 0.22 to 0.60, and that of the trisection method ranged from 0.17 to 0.57. Neither linear estimation method's reliability uniformly improved with the use of overlay templates. Intraobserver agreement without overlay templates ranged from 0.17 to 0.49 for the whole clock face, 0.11 to 0.47 for the half clock face, 0.01 to 0.66 for the quadrant method, and 0.20 to 0.57 for the trisection method. Use of overlay templates did not uniformly improve intraobserver agreement for any estimation method.

CONCLUSIONS

There does not appear to be any advantage of using a half clock face or compass for estimating femoral tunnel position compared with a whole clock-face analogy. Visual reference aids appear to improve interobserver agreement (reliability) of circular analogies. The linear quadrant appears to be the most reliable method (fair to moderate agreement) for estimating femoral tunnel position without a visual aid for reference, but even better reliability, ranging from fair to good agreement, may be obtained by using the whole clock-face analogy with a visual aid.

CLINICAL RELEVANCE

Increasing femoral tunnel position reliability may improve outcomes of ACL reconstruction surgery.

Graft-bending angle and femoral tunnel length after single-bundle anterior cruciate ligament reconstruction: comparison of the transtibial, anteromedial portal and outside-in techniques

We used immediate post-operative in vivo three-dimensional computed tomography to compare graft bending angles and femoral tunnel lengths in 155 patients who had undergone single-bundle reconstruction of the anterior cruciate ligament using the transtibial (n = 37), anteromedial portal (n = 72) and outside-in (n = 46) techniques. The bending angles in the sagittal and axial planes were significantly greater but the coronal-bending angle was significantly less in the transtibial group than in the anteromedial portal and outside-in groups (p < 0.001 each). The mean length of the femoral tunnel in all three planes was significantly greater in the transtibial group than the anteromedial portal and outside-in groups (p < 0.001 each), but all mean tunnel lengths in the three groups exceeded 30 mm. The only significant difference was the coronal graft- bending angle in the anteromedial portal and outside-in groups (23.5° vs 29.8°, p = 0.012). Compared with the transtibial technique, the anteromedial portal and outside-in techniques may reduce the graft-bending stress at the opening of the femoral tunnel. Despite the femoral tunnel length being shorter in the anteromedial portal and outside-in techniques than in the transtibial technique, a femoral tunnel length of more than 30 mm in the anteromedial portal and outside-in techniques may be sufficient for the graft to heal.

Popliteal artery pseudoaneurysm after anterior cruciate ligament re-revision using a rigidfix cross pin

Popliteal artery injury is a very rare complication of anterior cruciate ligament (ACL) reconstruction. The authors experienced a case of popliteal arterial pseudoaneurysm after re-revision of ACL reconstruction using Rigidfix for femoral tunnel fixation. Pseudoaneurysm was detected in knee magnetic resonance imaging, which caused pain, limit of motion, common peroneal nerve palsy, leg swelling and symptoms similar to compartment syndrome. After excision and re-anastomosis of the popliteal artery using a greater saphenous vein graft, all symptoms were resolved within 3 months except for common peroneal nerve palsy. So we report on this case with a review of the literature.

Correlation between femoral tunnel length and tunnel position in ACL reconstruction

BACKGROUND

The position of the femoral tunnel affects the osseous geometry available for drilling during anterior cruciate ligament (ACL) reconstruction. The length of the tunnel changes with changes in the tunnel position and may have implications for femoral fixation.

METHODS

Forty-seven patients with a single-bundle ACL reconstruction underwent computed tomography (CT) evaluation to generate three-dimensional (3D) CT bone models. With use of a previously described anatomic coordinate system, the center of the femoral tunnel was quantified in the posterior-anterior and proximal-distal dimensions on 3D CT. Tunnel length was defined as the distance between the centers of the intra-articular and extra-articular tunnel apertures. The reconstructed knees were dichotomized by anatomy and technique into anatomic (n = 20) and nonanatomic (n = 27) groups as well as according to whether they had undergone medial portal drilling (n = 20) or transtibial drilling (n = 27) for analysis. In addition, a review of the literature on the relationship between tunnel length and tendon-to-bone healing was performed.

RESULTS

Femoral tunnels drilled with nonanatomic footprints were longer (mean [and standard deviation], 43.6 ± 8.5 mm; range, 28.2 to 60.7 mm) than tunnels drilled with anatomic footprints (31.0 ± 6.3 mm; 21.2 to 42.5 mm) (p &lt; 0.001). Tunnels drilled transtibially (44.4 ± 7.6 mm; 32.5 to 60.7 mm) were significantly longer than tunnels drilled through the medial portal (29.8 ± 5.0 mm; 21.2 to 40.3 mm) (p &lt; 0.001). There was a strong correlation between tunnel length and posterior-anterior femoral tunnel position (r = 0.78, p &lt; 0.05), with more anterior tunnel positioning associated with greater tunnel length. There was no correlation between posterior-distal femoral tunnel position and tunnel length (r = -0.05; p = 0.74). There was no consensus in the literature regarding adequate tunnel length for biologic fixation.

CONCLUSIONS

Femoral tunnels drilled with anatomic footprints had sufficient length for adequate femoral fixation. Femoral tunnels positioned anterior to the native insertion of the ACL were longer than those in anatomic position.

CLINICAL RELEVANCE

The results of this study can help the surgeon to consider the relationship between tunnel position and subsequent tunnel length in ACL reconstruction.

Transtibial versus independent drilling techniques for anterior cruciate ligament reconstruction: a systematic review, meta-analysis, and meta-regression

BACKGROUND

While numerous cadaveric, in vivo, and clinical studies have compared transtibial and independent drilling of femoral tunnels during anterior cruciate ligament reconstruction, there is no evidence-based consensus on which technique affords the best outcome.

HYPOTHESIS

There is no difference in clinical outcome between transtibial and independent drilling of femoral tunnels.

STUDY DESIGN

Systematic review with meta-analysis and meta-regression.

METHODS

Cadaveric, in vivo, and clinical studies comparing transtibial and independent drilling techniques were systematically identified. A qualitative synthesis of nonrandomized studies and meta-analysis of randomized controlled trials (RCTs) were performed. In addition, a meta-regression analysis of RCTs that did not directly compare drilling techniques was performed.

RESULTS

A total of 49 studies were included in the qualitative review, and 15 were included in the meta-analysis; 22 studies were included in the meta-regression. In biomechanical studies, independent drilling placed the center of the femoral tunnel closer to the center of the femoral footprint (mean difference, 2.69 mm; 95% CI, 0.46-4.92; P < .00001). Independent drilling reduced anterior tibial translation with the Lachman examination (mean difference, 2.2 mm; 95% CI, 0.34-4.07; P = .02), 134 N of anterior load (mean difference, 1 mm; 95% CI, 0.29-1.71; P = .006), and simulated pivot shift (mean difference, 3.36 mm; 95% CI, 1.88-4.85; P < .00001). The meta-analysis showed improved Lysholm scores with independent drilling (mean difference, -0.62 points; 95% CI, -1.09 to -0.55; P = .009), although the clinical relevance of this small difference is questionable. There were no significant differences in International Knee Documentation Committee (IKDC) objective scores or Tegner scores between groups. With the meta-regression, there were no significant differences in failure rates or IKDC objective scores.

CONCLUSION

While there are biomechanical data suggesting improved knee stability and more anatomic graft placement with independent drilling, no significant clinical differences were found between the 2 techniques.

CLINICAL RELEVANCE

The current evidence shows that transtibial and independent drilling techniques have equivalent clinical outcomes at short-term to midterm follow-up. The long-term effects of subtle differences in tunnel position and postoperative knee kinematics should be further studied in dedicated, prospective cohort and randomized studies.

Anteromedial portal versus outside-in technique for creating femoral tunnels in anatomic anterior cruciate ligament reconstructions

PURPOSE

To determine whether the anteromedial (AM) portal and outside-in techniques in anterior cruciate ligament reconstruction differ (1) in the coronal femoral tunnel position, (2) in the femoral tunnel length, and (3) in the incidence of femoral tunnel-related complications, such as femoral socket blowout.

METHODS

We examined 63 knees undergone primary anterior cruciate ligament reconstructions using the AM portal technique (AM portal group) and 54 knees using the outside-in technique (outside-in group). Coronal femoral tunnel positions between the 2 groups were assessed on postoperative tunnel-view radiographs and compared. Comparisons of femoral tunnel lengths, proportions of knees with a femoral tunnel length of less than 30 mm, and incidences of femoral tunnel-related complications were performed between the 2 groups.

RESULTS

There were no significant differences in coronal femoral tunnel positions between the AM portal and outside-in groups (56.6° v 56.4°, P > .99). Differences in femoral tunnel lengths between the AM portal and outside-in groups did not reach statistical significance (37.6 mm and 39.0 mm, respectively; P = .097), but the tunnel length of the outside-in group showed smaller variation than that of the AM portal group in terms of standard deviation (2.7 v 6.0). In addition, the AM portal group had a significantly greater proportion of knees with a femoral tunnel length of less than 30 mm than the outside-in group (14% v 0%, P = .004). There were 2 tunnel-related complications (3%) (highly suspicious cortical blowouts) in the AM portal group and none in the outside-in group (P = .499).

CONCLUSIONS

This study shows that compared with the AM portal technique, the outside-in technique can achieve a similar femoral tunnel position in the coronal plane with a reduced chance of a femoral tunnel length of less than 30 mm.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Comparison of tunnel locations of double bundle ACL reconstruction using the conventional transtibial technique with anatomic tunnel locations using a 3D CT model

INTRODUCTION

The purposes of this study were: (1) to compare tunnel locations using the conventional transtibial technique with reference data, and (2) to identify factors that make it difficult to position the femoral tunnel correctly or contribute to breakage of the bone bridge between the two tibial tunnels.

MATERIALS AND METHODS

A prospective study was performed on 28 patients who underwent double bundle ACL reconstruction. Locations of each tunnel were determined using an anatomic coordinate axes method (ACAM). Measurements included: thickness of the bone bridge between tibial two tunnels (BB), height from the union (HU) point to expected joint surface, the ratio between the length of Blumensaat's line and the anterior-posterior length of the lateral femoral condyle (RBL), and the ratio between anterior-posterior and proximal-distal lengths of the medial wall of the lateral femoral condyle (RAPPD).

RESULTS

The posterior-anterior direction of femoral AM tunnel, the proximal-distal direction of femoral PL tunnel, and the posterior-anterior direction of femoral PL tunnel were statistically significantly different from the reference data. In correlation analyses between BB or HU and other variables, the AM tibial tunnel and RBL showed a moderate negative correlation. The cutoff point for tunnel breakage was an RLB of 1.14, meaning that the possibility of bone bridge breakage would increases for RBL values of >1.14.

CONCLUSIONS

It seems that conventional transtibial drilling technique used during double bundle ACL reconstruction does not reproduce correct tunnel locations compared with reference data. This problem was found to be related to the bony geometry of the medial wall of the lateral femoral condyle or the bone bridge between the two tibial tunnels. Our results indicate that RBL should be determined by pre-operative CT or plain lateral radiography, and that transtibial single bundle reconstruction or double bundle reconstruction using other methods should be attempted when the RBL exceeds 1.14.

Anteromedial versus transtibial tunnel drilling in anterior cruciate ligament reconstructions: a systematic review

PURPOSE

Failure to anatomically reconstruct the femoral footprint can lead to rotational instability and clinical failure. Thus we sought to compare femoral tunnel drilling techniques, specifically anteromedial (AM) and transtibial (TT) methods, with respect to rotational stability.

METHODS

In this study we evaluated available scientific support for the ability of both techniques to achieve rotational stability of the knee through a systematic review of the literature for directly comparative biomechanical and clinical studies.

RESULTS

We identified 9 studies (5 clinical Level II or III studies and 4 cadaveric studies) that directly compared AM and TT techniques. Three cadaveric and 2 clinical studies showed superior rotational stability with the AM technique as compared with the TT technique, whereas 2 cadaveric studies and 1 clinical study were unable to show any similar differences. Two studies showed superior clinical outcomes with the AM technique, whereas 3 studies were unable to show any difference.

CONCLUSIONS

In this systematic review of clinical and biomechanical studies directly comparing AM and TT techniques for anterior cruciate ligament reconstruction (ACLR) in the literature, there are mixed results, with some studies finding superior rotational stability and clinical outcomes with the AM technique and some finding no difference. No studies showed significantly better results with the TT technique. This study shows that the AM portal technique for ACLR may be more likely to produce improved clinical and biomechanical outcomes but that the TT technique is capable of producing similar outcomes.

LEVEL OF EVIDENCE

Level III, systematic review of Level II and III studies plus cadaver studies.

Comparison of femoral tunnel length between transportal and retrograde reaming outside-in techniques in anterior cruciate ligament reconstruction

PURPOSE

To evaluate the accuracy of intraoperative femoral tunnel length measurement and to compare this between the transportal (TP) and outside-in (OI) techniques for double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

METHODS

Eighty patients underwent a DB ACL reconstruction using either the TP or the OI technique. The participants were randomized to either a TP group (I, 40 cases) or a OI group (II, 40 cases). The intraoperatively measured femoral tunnel length was recorded, and the postoperative femoral tunnel length was measured using computed tomography with OsiriX(®) imaging software.

RESULTS

The mean femoral tunnel lengths measured intraoperatively in Group II (38.9 ± 3.0 mm for anteromedial [AM], 39.3 ± 3.4 mm for posterolateral [PL]) were significantly longer than those of Group I (34.8 ± 2.7 mm for AM, 36.0 ± 3.2 mm for PL) (P < 0.001). The mean AM femoral tunnel length measured postoperatively in Group II (33.3 ± 3.8 mm) was significantly longer than that in Group I (31.1 ± 2.9 mm) (P = 0.006). The mean intraoperatively measured femoral tunnel length was significantly longer than that measured postoperatively in Groups I and II (P < 0.001).

CONCLUSION

After anatomic DB ACL reconstruction, the femoral tunnel length of the OI technique measured intraoperatively (AM/PL) and postoperatively (AM) was longer than those of the TP technique. The femoral tunnel length measured intraoperatively was longer than that measured postoperatively in both TP and OI technique. This study may help surgeons to measure femoral tunnel length accurately in anatomic DB ACL reconstruction with suspensory fixation device.

Transtibial versus low anteromedial portal drilling for anterior cruciate ligament reconstruction: a radiographic study of femoral tunnel position

PURPOSE

The purpose of this study is to compare femoral tunnel positions after ACL reconstruction by the transtibial (TT) approach versus the low anteromedial approach using radiographs from a single surgeon.

METHODS

The standard postoperative knee radiographs of 50 patients with an ACL reconstruction were studied. Two groups were determined according to the technique used. The low anteromedial portal group and the transtibial portal group. The femoral bone tunnel was identified radiographically, and its position determined in the lateral and A-P view. Coronal and sagittal obliquity of the tunnel was measured and compared among both groups.

RESULTS

In the sagittal plane, femoral bone tunnels averaged 54° ± 6° for the TT technique and 59° ± 12° (p = 0.07) for the low anteromedial portal technique. In the coronal plane, the bone tunnels drilled through the low anteromedial portal showed a significantly more oblique femoral tunnel position (50° ± 6°) compared to TT drilling (58° ± 9°), p ≤ 0.05.

CONCLUSION

Drilling the femoral tunnel through the low anteromedial portal resulted in a more oblique femoral tunnel position compared to the TT technique. Clinically, the low anteromedial portal may allow to better restore the anatomic orientation of the ACL.

Increased risk of revision after anteromedial compared with transtibial drilling of the femoral tunnel during primary anterior cruciate ligament reconstruction: results from the Danish Knee Ligament Reconstruction Register

PURPOSE

The goal was to study revision rates and clinical outcome after anterior cruciate ligament (ACL) reconstruction using the anteromedial (AM) technique versus the transtibial (TT) technique for femoral drill hole placement.

METHODS

A total of 9,239 primary ACL reconstruction procedures were registered in the Danish Knee Ligament Reconstruction Register between January 2007 and December 2010. The failure of the 2 different femoral drilling techniques was determined using revision ACL reconstruction as the primary endpoint. As secondary endpoints, we used the pivot-shift test and instrumented objective test as well as patient-reported outcome, registered in the Danish Knee Ligament Reconstruction Register. Relative risks (RRs) with 95% confidence intervals (CI) were calculated.

RESULTS

We identified 1,945 AM and 6,430 TT primary ACL procedures. The cumulative revision rates for ACL reconstruction after 4 years with the AM and TT techniques were 5.16% (95% CI: 3.61%, 7.34%) and 3.20% (95% CI: 2.51%, 4.08%), respectively. The adjusted overall RR for revision ACL surgery in the AM group was 2.04 (95% CI: 1.39, 2.99), compared with the TT group. Use of the AM technique increased from 13% of all operations in 2007 to 40% in 2010. AM technique was further associated with increased RRs of positive pivot shift of 2.86 (95% CI: 2.40, 3.41) and sagittal instability of 3.70 (95% CI: 3.09, 4.43), compared with the TT technique.

CONCLUSIONS

This study found an increased risk of revision ACL surgery when using the AM technique for femoral drill hole placement, compared with the TT technique, in the crude data as well as the stratified and adjusted data. Our finding could be explained by technical failures resulting from introduction of a new and more complex procedure or by the hypothesis put forward in prior studies that compared with a nonanatomic graft placement, a greater force is carried by the anatomic ACL reconstruction and, hence, there is a concomitant higher risk of ACL rupture.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Femoral cross-pin breakage and its effects on the results of anterior cruciate ligament reconstruction using a hamstring autograft

PURPOSE

The primary aim was to determine the rate and risk factors of double biodegradable femoral cross-pin breakage after anterior cruciate ligament reconstruction using a hamstring autograft. In addition, we compared clinical outcomes and magnetic resonance imaging (MRI) findings related to grafts for knees with and without a broken cross-pin.

METHODS

A retrospective review of 53 knees (53 patients) was performed. Cross-pin breakage was determined by follow-up MRI. Age, sex, weight, height, presence of a posterior transcortical cross-pin breach, time between surgery and follow-up MRI, graft diameter, and cross-pin position (superior or inferior) were included in the analysis. Differences in Lysholm knee scores, International Knee Documentation Committee grades, anterior laxity, and pivot-shift test results were examined in relation to cross-pin breakage. In addition, anterior cruciate ligament graft integrity and osseous graft integration by MRI were assessed and compared between knees with broken cross-pins and knees with intact cross-pins.

RESULTS

A cross-pin was broken in 25 of 53 knees. A cross-pin posterior transcortical breach was the only factor found to be significantly correlated with cross-pin breakage (odds ratio, 6.117; P = .033) by univariate analysis. No significant differences in clinical outcomes were found to be related to cross-pin breakage, but femoral tunnel enlargement was more frequent in knees with breakage than in those without (P = .002).

CONCLUSIONS

Breakage of biodegradable cross-pins used for femoral fixation is relatively common but did not affect clinical outcomes. However, femoral tunnel enlargement was found to be greater in knees with a broken cross-pin. The only significant relation found was between a cross-pin posterior transcortical breach and breakage, which suggests that pin breakage is related to a technical error. These findings should be borne in mind when a double biodegradable cross-pin is being considered for femoral fixation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Femoral graft bending angle and femoral tunnel geometry of transportal and outside-in techniques in anterior cruciate ligament reconstruction: an in vivo 3-dimensional computed tomography analysis

PURPOSE

To compare femoral graft bending angles and femoral tunnel geometries between the transportal (TP) and outside-in (OI) techniques after anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

METHODS

Thirty-nine patients underwent DB ACL reconstruction with the TP and OI techniques. They were randomized on the day of surgery to either the TP group (group I, 21 cases) or the OI group (group II, 18 cases). Femoral graft bending angle, femoral tunnel geometry, posterior wall breakage, and tunnel communication were assessed by computed tomography imaging with OsiriX imaging software (Pixmeo, Geneva, Switzerland).

RESULTS

The mean anteromedial (AM) and posterolateral (PL) femoral graft bending angles of group II (97.3° ± 8.3° and 97.4° ± 8.6°, respectively) were significantly more acute than those of group I (108.2° ± 8.4° and 109.9° ± 8.8°, respectively) (P < .001). The mean AM femoral tunnel length of group II (34.3 ± 3.9 mm) was significantly longer than that of group I (31.9 ± 2.7 mm) (P = .02). However, the mean PL femoral tunnel lengths did not differ between groups. In 7 cases-4 cases (19.0%) in group I and 3 cases (16.6%) in group II-the femoral tunnel communication was found around the intra-articular aperture. Posterior wall breakage was observed in 5 cases (23.8%), which were all in AM femoral tunnels of group I.

CONCLUSIONS

The OI technique resulted in more acute femoral graft bending angles (difference of 10.9° and 12.5° for AM and PL, respectively) and longer mean AM femoral tunnel lengths (difference of 2.4 mm) than the TP technique after anatomic DB ACL reconstruction, even though these small differences might be unlikely to be of clinical significance. Femoral tunnel communication was found in both groups, and posterior wall breakage was observed in AM femoral tunnels with the TP technique.

LEVEL OF EVIDENCE

Level I, prospective randomized trial.