The relationship between tunnel placement and clinical results after anterior cruciate ligament reconstruction

Revision anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) graft failure from rupture, attenuation, or malposition may cause recurrent subjective instability and objective laxity, and occurs in 3% to 22% of ACL reconstruction (ACLr) procedures. Revision ACLr is often indicated to restore knee stability, improve knee function, and facilitate return to cutting and pivoting activities. Prior to reconstruction, a thorough clinical and diagnostic evaluation is required to identify factors that may have predisposed an individual to recurrent ACL injury, appreciate concurrent intra-articular pathology, and select the optimal graft for revision reconstruction. Single-stage revision can be successful, although a staged approach may be used when optimal tunnel placement is not possible due to the position and/or widening of previous tunnels. Revision ACLr often involves concomitant procedures such as meniscal/chondral treatment, lateral extra-articular augmentation, and/or osteotomy. Although revision ACLr reliably restores knee stability and function, clinical outcomes and reoperation rates are worse than for primary ACLr.

Computer-assisted navigation in ACL reconstruction improves anatomic tunnel placement with similar clinical outcomes

BACKGROUND

While the use of navigation systems in anterior cruciate ligament (ACL) reconstruction theoretically improves tunnel placement accuracy and clinical outcomes, the existing literature remains inconclusive. We aimed to evaluate the potential benefits of navigated ACL reconstruction on tunnel placement and clinical outcomes.

METHODS

In this retrospective study, we evaluated a cohort of patients who underwent conventional or navigated (OrthoPilot system) primary ACL reconstruction at our institution from June 2004 to October 2009. Anteroposterior and lateral radiographic knee assessments were evaluated to assess postoperative tunnel positioning. Clinical outcomes, including the International Knee Documentation Committee classification, Lysholm score, and Tegner score, were evaluated preoperatively and 1-year postoperatively. Radiographic and clinical outcomes were compared and analysed using independent 2-sample t-tests and Chi-square tests.

RESULTS

Sixty patients met the inclusion criteria and were included for analysis, comprising of 26 navigated and 34 conventional reconstructions. Postoperative radiographs showed no differences in tibial tunnel position between both groups, but a significantly smaller deviation from the recommended position in the navigated group (navigated: 5.96 %; conventional: 7.92 %; p = 0.008). Femoral tunnel placements in the navigated group were significantly more perpendicularly away from the Blumensaat line (navigated: 38.90 %; conventional: 31.94 %; p = 0.001), with a greater deviation from recommended position (navigated: 11.00 %; conventional: 6.94 %; p = 0.009). There were no differences in 1-year postoperative clinical outcomes (p > 0.05).

CONCLUSION

Navigated ACL reconstruction resulted in a more anatomic femoral tunnel placement and similar clinical outcomes as conventional reconstruction. Further research should be conducted to clarify the potential biomechanical and clinical impacts of navigated ACL reconstruction.

Failure rate analysis and clinical outcomes of two different femoral tunnel positions using anteromedial portal technique in anterior cruciate ligament reconstruction

AIM

To analyze two different femoral tunnel positions and to evaluate their correlation with clinical, functional outcomes and surgical revision rate in patients who underwent primary arthroscopic anterior cruciate ligament (ACL) reconstruction with anteromedial (AM) portal technique.

METHODS

From January 2015 to October 2018, we recruited 244 patients that underwent primary single-bundle ACL reconstruction, using four strand-semitendinosus graft and AM portal technique for femoral tunnel placement. Patients were divided into two groups based on the different femoral tunnel positions: 117 patients of group A had ACL footprint center femoral tunnel position compared with 127 patients of group B, with femoral tunnel placement close to the AM bundle footprint. Preoperatively and at last follow up, all patients were assessed subjectively by Lysholm, Tegner, and International Knee Documentation Committee (IKDC) scores, while Lachman, Pivot-shift, and KT-1000 tests were performed to evaluate knee joint stability.

RESULTS

Group B patients showed significantly better results in Lysholm, objective, and subjective IKDC scores compared with patients of group A (P < 0.001). A significantly higher surgical failure rate was found in group A than in group B (10.26% vs. 2.3%; P < 0.001). A higher anterior knee laxity was recorded in patients of group A than in patients of group B (1.9 ± 1.1 vs. 1.3 ± 1 mm; P < 0.001); a reduction in mean anterior tibial translation from preoperative to final follow up was found in group B compared with group A (3.5 ± 1.2 vs. 2.7 ± 1.1 mm; P < 0.001). No significant differences in the Tegner scale were found between the two groups.

CONCLUSION

ACL reconstruction performed using the AM portal technique showed better and more satisfactory clinical and functional outcomes associated with a lower failure rate when the femoral tunnel had been placed more eccentrically in the footprint, in the AM bundle center position.

Posteriorly positioned femoral grafts decrease long-term failure in anterior cruciate ligament reconstruction, femoral and tibial graft positions did not affect long-term reported outcome

PURPOSE

To investigate the effect that femoral and tibial tunnel positions have on long-term reported and clinical outcome and to identify a safe zone based on favourable outcome.

METHODS

Seventy-eight patients from a previous randomised controlled trial were included and were followed with a mean follow-up of 11.4 years. All patients had primary trans-tibial anterior cruciate ligament reconstruction performed. The femoral and tibial tunnel positions were visualised and translated in percentages with three-dimensional computed tomography post-operatively. There were 3 separate outcome variables: patient-reported outcome measured with the IKDC Subjective Knee Form, overall failure, and radiographic osteoarthritis. The correlation between tunnel aperture positions and outcome was determined with multivariate regression. The area with best outcome was defined as the safe zone and was determined with Youden's index in conjunction with receiver operating characteristics.

RESULTS

No significant relationship was found between tunnel aperture positions and IKDC Subjective Knee Form at 10-year follow-up. The posterior-to-anterior femoral tunnel aperture position parallel to Blumensaat line showed a significant relationship (p = 0.03) to overall failure at 10-year follow-up. The mean posterior-to-anterior tunnel position of the group that did not fail was 37.7% compared to 44.1% in the overall failure group. Femoral tunnel apertures placed further anteriorly had more overall failures at long-term. The cut-off point lies at 35.0% from posterior-to-anterior parallel to Blumensaat. Of the 16 overall failures, 15 (93.8%) were placed further anteriorly than the cut-off point. No significant relationship was found between tunnel aperture positions and radiographic osteoarthritis.

CONCLUSION

Femoral and tibial tunnel positions were not associated with long-term patient-reported outcome and radiographic osteoarthritis. Long-term overall failure was more frequently seen in patients with a more anteriorly placed femoral tunnel. This study identified a safe zone located at the most posterior 35% of the femoral condyle parallel to Blumensaat. This knowledge offers guidance to surgeons to operate more precisely and accurately and reconstruct a long-lasting graft.

LEVEL OF EVIDENCE

Level III.

Biomechanical Effects of Aspect Ratio of the Knee during Outside-In Anterior Cruciate Ligament Reconstruction Surgery

We analyzed tunnel length, graft bending angle, and stress of the graft according to tunnel entry position and aspect ratio (ASR: ratio of anteroposterior depth to mediolateral width) of the articular surface for the distal femur during single-bundle outside-in anterior cruciate ligament reconstruction (ACLR) surgery. We performed multiflexible body dynamic analyses with four ASR (98, 105, 111, and 117%) knee models. The various ASRs were associated with approximately 1 mm changes in tunnel length. The graft bending angle increased when the entry point was far from the lateral epicondyle and was larger when the ASR was smaller. The graft was at maximum stress, 117% ASR, when the tunnel entry point was near the lateral epicondyle. The maximum stress value at a 5 mm distance from the lateral epicondyle was 3.5 times higher than the 15 mm entry position, and the cases set to 111% and 105% ASR showed 1.9 times higher stress values when at a 5 mm distance compared with a 15 mm distance. In the case set at 98% ASR, the low-stress value showed a without-distance difference from the lateral epicondyle. Our results suggest that there is no relationship between the ASR and femoral tunnel length. A smaller ASR causes a higher graft bending angle, and a larger ASR causes greater stress in the graft.

Novice Surgeon Portal Preference to Visualize the Femoral Anterior Cruciate Ligament Footprint: The Accessory Medial Portal Offers Improved Visualization

Purpose

To evaluate participant opinions on the appropriateness of different viewing angles by asking 8 questions, using visual content techniques.

Methods

Survey information from participants was used in this study. We used images of a patient who was operated on for symptomatic knee instability. Participants were asked whether the visual angle could determine the femoral tunnel entry point or evaluate anterior cruciate ligament (ACL) integrity.

Results

Questionnaires were completed by 40 participants. When all responses were evaluated, participant opinions on the accessory medial portal (AMP) were more positive than opinions on images taken from the anterolateral portal (ALP). These observations were statistically significant (P < .005). Both ACL integrity assessments and femoral tunnel entry site questions were evaluated, we observed that participant opinions on the AMP for both types of evaluation were more positive than opinions on the ALP. This observation was statistically significant (P < .005). When evaluations with photos and video transcripts were compared, no significant differences in terms of participant opinions were observed (P < .005).

Conclusions

AMP use may be a valuable tool for assistant and postgraduate education, as it offers a more suitable view angle for ACL reconstruction.

Level of evidence

Level V, survey study.

Influence of selected plane on the evaluation of tibial tunnel locations using a three-dimensional bone model in double-bundle anterior cruciate ligament reconstruction

BACKGROUND

The purpose of this study was to investigate the influence of a selected plane on the evaluation of tibial tunnel locations following anterior cruciate ligament reconstruction (ACLR) between two planes: the plane parallel to the tibial plateau (Plane A) and the plane perpendicular to the proximal tibial shaft axis (Plane B).

METHODS

Thirty-four patients who underwent double-bundle ACLR were included. Three-dimensional model of tibia was created using computed tomography images 2 weeks postoperatively, and tibial tunnels of the anteromedial bundle (AMB) and posterolateral bundle (PLB) were extracted. To evaluate tibial tunnel locations, two planes (Planes A and B) were created. The locations of the tibial tunnel apertures of each bundle were evaluated using a grid method and compared between Planes A and B. The difference in coronal alignment between Planes A and B were also assessed.

RESULTS

The AMB and PLB tunnel apertures in Plane A were significantly more laterally located than in Plane B (mean difference; AMB, 1.5%; PLB, 1.7%, P < 0.01). There were no significant differences in the anteroposterior direction between the planes. Coronal alignment difference between the planes was 16.8 ± 2.2°; Plane B was more valgus than Plane A.

CONCLUSION

Although tibial tunnel locations were not significantly influenced by the selected planes in the AP direction, subtle but statistically significant differences were found in the ML direction between the Planes A and B in double-bundle anterior cruciate ligament reconstruction. The findings suggest that both Planes A and B can be used in the assessment of tibial tunnel locations after anterior cruciate ligament reconstruction.

Inclination of Blumensaat's line influences on the accuracy of the quadrant method in evaluation for anterior cruciate ligament reconstruction

PURPOSE

The quadrant method is used to evaluate the bone tunnel position with the grid based on the Blumensaat's line in anterior cruciate ligament (ACL) reconstruction. This study aimed to clarify the influence of variation in the Blumensaat's line on the accuracy of the quadrant method measurements.

METHODS

A retrospective review of the radiological records of patients aged 18-30 years who underwent computed tomography (CT) scanning of the knee joint was conducted. The Blumensaat's line inclination angle (BIA), along with the most posterior point of the posterior condyle (point P) position using the quadrant method and morphology of the Blumensaat's line were measured on true lateral transparent three-dimensional CT images of the distal femoral condyle in 147 patients. Statistical analysis was conducted to determine associations among these measurements.

RESULTS

BIA was 37.5° (standard deviation 4.2°; range 27°-48°). The point P position was significantly correlated with BIA in the high/low (R² = 0.590, P < 0.0001) and deep/shallow (R² = 0.461, P < 0.0001) directions. The morphology of the Blumensaat's line was straight in 35 knees (23.8%); whereas, the remaining 112 knees (76.2%) were not straight but had some hill on the Blumensaat's line. No significant difference among the morphological variation of the Blumensaat's line was observed in BIA and the point P position.

CONCLUSION

There was a strong correlation between BIA and the point P measured using the quadrant method, suggesting the influence of the Blumensaat's line on the accuracy of the quadrant method measurements in ACL reconstruction. As for the clinical relevance, surgeons should be careful in application of the quadrant method for ACL reconstruction, because the variation of the Blumensaat's line inclination influences the accuracy of this method.

Techniques for Femoral Socket Creation in ACL Reconstruction

Anterior cruciate ligament (ACL) injury is common and affects a wide variety of individuals. An ACL reconstruction is the treatment of choice for patients with subjective and objective symptoms of instability and is of particular importance to cutting or pivoting athletes. With many variables involved in ACL reconstruction, femoral tunnel placement has been found to affect clinical outcomes with nonanatomic placement being identified as the most common technical error. Traditionally the femoral tunnel was created through the tibial tunnel or transtibial with the use of a guide and a rigid reaming system. Because of proximal, nonanatomic tunnel placement using the transtibial technique, the use of the anteromedial portal and outside-in drilling techniques has allowed placement of the tunnel over the femoral footprint. In this paper, we discuss the difference between the 3 techniques and the advantages and disadvantages of each. The authors then explore the clinical differences and outcomes in techniques by reviewing the relevant literature.

Comparison of Postoperative Tunnel Widening After Hamstring Anterior Cruciate Ligament Reconstructions Between Anatomic and Nonanatomic Femoral Tunnels

PURPOSE

To evaluate the effect of the location of the femoral tunnel on 3-dimensional (3D) computed tomography (CT) upon the postoperative tunnel widening after anterior cruciate ligament (ACL) reconstructions.

METHODS

Inclusion criteria were patients who underwent hamstring ACL reconstructions using an adjustable-loop cortical suspension device, underwent 3D CT at the day after surgery, and were followed for a minimum of 2 years after surgery. Exclusion criteria were patients with combined ligament injury and reinjury after reconstruction. Using 3D CT, the center of the femoral tunnel aperture was located on a standardized grid system. The center of the ACL footprint was defined from the literature. The femoral tunnel location was classified as anatomic if it located within 2 standard deviations of the center position. If it was outside the 2 standard deviations, the tunnel was classified as nonanatomic. The patients were divided into either anatomic or nonanatomic groups. Femoral tunnel angles on both sagittal and coronal planes were measured. Both femoral and tibial tunnels measured on anteroposterior and lateral radiographs at immediate postoperative day and at 2 years after surgery. Postoperative knee stability and patient-reported outcomes were evaluated.

RESULTS

There were 37 patients in anatomical group and 52 patients in nonanatomical group among enrolled 87 patients. There were no differences in demographics between the 2 groups. There were no differences in the femoral tunnel angles and postoperative tunnel widening between the 2 groups. A higher position correlated to the femoral tunnel widening at 2 years postoperatively. Postoperative knee stability and patient-reported outcomes showed no statistically significant differences between the 2 groups.

CONCLUSIONS

There was no significant difference in postoperative tunnel widening or clinical outcomes between anatomic and nonanatomic femoral tunnel location after hamstring ACL reconstructions. A higher position correlated to the femoral tunnel widening at 2 years postoperatively.

LEVEL OF EVIDENCE

Level III, Retrospective comparative study.

Biomechanical Evidence on Anterior Cruciate Ligament Reconstruction

Objective  Anterior cruciate ligament (ACL) reconstruction is recommended in athletes with high physical demands. Several techniques are used in reconstruction; however, the most relevant question still is the best biomechanical positioning for the graft. The present study aimed to analyze the biomechanical effect of the position of bone tunnels on load distribution and joint kinetics, as well as the medium-term functional outcomes after ACL reconstruction.

Methods  A biomechanical study using a finite element model of the original knee (without anterior cruciate ligament rupture) and reconstruction of the ACL (neoACL) was performed in four combinations of bone tunnel positions (central femoral-central tibial, anterior femoral-central tibial, posterosuperior femoral-anterior tibial, and central femoral-anterior tibial) using the same type of graft. Each neo-ACL model was compared with the original knee model regarding cartilaginous contact pressure, femoral and meniscal rotation and translation, and ligamentous deformation.

Results  No neo-ACL model was able to fully replicate the original knee model. When the femoral tunnel was posteriorly positioned, cartilage pressures were 25% lower, and the mobility of the meniscus was 12 to 30% higher compared with the original knee model. When the femoral tunnel was in the anterior position, internal rotation was 50% lower than in the original knee model.

Conclusion  Results show that the femoral tunnel farther from the central position appears to be more suitable for a distinct behavior regarding the intact joint. The most anterior position increases rotational instability.

Computed Tomography Assessment of Anatomic Graft Placement After ACL Reconstruction: A Comparative Study of Grid and Angle Measurements

Background:

The anatomic placement of anterior cruciate ligament (ACL) grafts is often assessed with postoperative imaging. In clinical practice, graft angles are measured to indicate anatomic placement on magnetic resonance imaging, whereas grid measurements are performed on computed tomography (CT). Recently, a study indicated that graft angle measurements could also be assessed on CT. No consensus has yet been reached on which measurement method is best suited to assess anatomic graft placement.

Purpose:

To compare the ability of grid measurements and angle measurements to identify anatomic versus nonanatomic tunnel placement on CT performed in patients undergoing ACL reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 100 knees undergoing primary reconstruction with a hamstring graft (HAM group), 91 undergoing reconstruction with a bone–patellar tendon–bone graft (BPTB group), and 117 undergoing revision ACL reconstruction (REV group) were assessed with CT. Grid measurements of the femoral and tibial tunnels and angle measurements of grafts were performed. Graft placement, rated as anatomic or nonanatomic, was assessed with both methods. Pearson chi-square, analysis of variance, Kruskal-Wallis, and weighted kappa tests were performed as appropriate.

Results:

The grid assessment classified 10% of the HAM group, 4% of the BPTB group, and 17% of the REV group as nonanatomic (P < .001). The angle assessment classified 37% of the HAM group, 54% of the BPTB group, and 47% of the REV group as nonanatomic. The weighted kappa between angle measurements and grid measurements was low in all groups (HAM: 0.009; BPTB: 0.065; REV: 0.041).

Conclusion:

The agreement between grid measurements and angle measurements was very low. The angle measurements seemed to overestimate nonanatomic tunnel placement. Grid measurements were better in identifying malpositioned grafts.

Single-tunnel anatomic double-bundle anterior cruciate ligament reconstruction has the same effectiveness as double femoral, double tibial tunnel: A prospective randomized study

PURPOSE

To investigate whether single femoral, single tibial tunnel anatomic double-bundle anterior cruciate ligament (ACL) reconstruction is equal to or superior to double femoral, double tibial tunnel ACL double-bundle anatomic reconstruction in terms of restoring the stability and functions of the knee joint.

METHODS

A prospective clinical study was performed to compare 30 cases of single-tunnel ACL double-bundle anatomic reconstruction to 28 cases of double-tunnel ACL double-bundle anatomic reconstruction, with average follow-up of 36 months. All graft tendons were hamstring tendon autografts. Tunnel placements in all the cases were made anatomically. Clinical results were collected after reconstruction. Graft appearance, meniscus status and cartilage state under arthroscopy were compared and analyzed.

RESULTS

Tunnel placements were in the anatomic positions in both groups. On the lateral pivot-shift test performed at 36 months postoperatively, there was no significant difference between groups. Clinical results such as International Knee Documentation Committee score, Tegner activity scale, and range of motion showed no significant differences between the groups. The mean thickness of anteromedial graft was reduced by 10.3% and that of the posterolateral graft was reduced by 11.1% from the original graft thickness evaluated by magnetic resonance imaging. No new meniscal tears were found either group; however, cartilage damage occurred in the double-tunnel group at 39.3%, and this rate was significantly higher than that in the single-tunnel group (10.0%).

CONCLUSION

Single femoral, single tibial tunnel anatomic double-bundle ACL reconstruction has the same effectiveness as the double femoral, double tibial tunnel in restoring the knee's stability and functions.

Radiological evaluation of tunnel position in single bundle anterior cruciate ligament reconstruction in the Indian population and their clinical correlation

BACKGROUND

Proper positioning of osseous tunnels during single bundle arthroscopic ACL reconstruction, which gives reproducibly good clinical outcome, is a matter of concern. Little evidence is there correlating tunnel position in arthroscopic ACL reconstruction with their clinical outcome in Indian population. Our aim in this study was to examine if the radiological tunnel-positions were significantly associated to the clinical outcomes.

METHODS

ACL reconstruction was performed in 147 young patients with an isolated ACL tear. They were followed up prospectively for the next two years. Clinical assessment of each patient was done using the International Knee Documentation Committee (IKDC) evaluation form before surgery and at two years later the surgery. At the same time, the radiological assessment was done on standard digital radiographs.

RESULTS

Considering the anterior and posterior-most points on the Blumensaat's line as 0% and 100% respectively the average position of the femoral tunnel was at 84.8%. Similarly, the tibial tunnel was at 46.8% along the tibial plateau. On the coronal plane the average position of the tibial tunnel was at 45.6% point along the tibial plateau (measured from the medial-most point towards laterally). The mean position of the femoral tunnel in the coronal plane was at 43.2% along the broadest part of the distal femur (measured from the lateral extent). The average inclination angle of the graft measured 19.6° (along the coronal plane).

CONCLUSION

Ideal clinical outcome was significantly associated with the placement of the femoral tunnel along the sagittal plane. Placement of the femoral tunnel should not be beyond the 85% mark along the Blumensaat's line from the anterior-most point. No correlation was established between clinical results and any of the remaining radiological parameters described above.

The posterior horn of the lateral meniscus is a reliable novel landmark for femoral tunnel placement in ACL reconstruction

PURPOSE

Femoral tunnel placement is essential for good outcome in anterior cruciate ligament (ACL) reconstruction. In the past, several attempts have been made to optimize femoral tunnel placement. It was observed that the posterior horn of the lateral meniscus was always located directly below to the desired femoral ACL tunnel position, when the knee was brought to deep flexion (> 120°). The goal of the present study was to verify the hypothesis that the posterior horn of the lateral meniscus can be used as a landmark for femoral tunnel placement.

METHODS

Out of a consecutive series of ACL reconstructions done by a single surgeon, 55 lateral radiographs were evaluated according to the quadrant method by Bernard and Hertel. Additionally, on anterior-posterior radiographs the femoral tunnel angle was determined.

RESULTS

In the present case series the posterior horn of the lateral meniscus could be identified and used as a landmark for femoral tunnel placement in all cases. The mean tunnel depth was 24 ± 5.1% and the mean tunnel height was 31.3 ± 5.7%. The mean femoral tunnel angle was 41 ± 4.9° using the anatomical axis as a reference. Compared to previous cadaver studies the data of the present study were within their anatomical range of the native ACL insertion site.

CONCLUSION

The suggested technique using the posterior horn of the lateral meniscus as a landmark for femoral tunnel placement showed reproducible results and matches the native ACL insertion site compared to previous cadaveric studies. In particular, non-experienced ACL surgeons will benefit from this apparent landmark and the corresponding easy-to-use ACL reconstruction method.

LEVEL OF EVIDENCE

IV.

Tibial tunnel placement in anatomic anterior cruciate ligament reconstruction: a comparison study of outcomes between patient-specific drill template versus conventional arthroscopic techniques

INTRODUCTION

Accurate anatomic graft tunnel positioning is essential for the successful application of anatomic anterior cruciate ligament (ACL) reconstruction. The accurate insertion of the tibial tunnel (TT) remains challenging. Here, we explored a novel strategy of patient-specific drill template (PDT) for the placement of TT in ACL reconstruction and assessed its efficacy and accuracy.

MATERIALS AND METHODS

TT placement was randomized and performed by use of the PDT technique in 40 patients (PDT group) and the conventional arthroscopic technique in 38 patients (Arthroscopic group). After surgery, the deviations at the center point of the ACL tibial attachment area and radiological TT positioning were assessed in both groups. The preoperative and follow-up examinations included pivot-shift testing, KT-1000 arthrometer testing, the Lysholm and International Knee Documentation Committee scales were used to compare the knee stability and the functional state.

RESULTS

The ideal center points achieved in the PDT group were more precise than that in the arthroscopic group (p < 0.001). Radiological TT positioning performed by use of the PDT technique was more accurate than that by the arthroscopic technique (p = 0.027). Statistical differences could not be found between the groups in terms of the pivot-shift test, KT-1000 arthrometer laxity measurements, the Lysholm or International Knee Documentation Committee scales. Both groups improved at follow-up compared with the preoperative assessment in terms of the pivot-shift test, the laxity tests, and scoring scales.

CONCLUSIONS

The novel PDT strategy could provide more accurate TT positioning than the traditional arthroscopic technique in ACL reconstruction. However, functional scales and stability tests gave similar results in the PDT and the standard techniques.

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.

Tunnel positioning assessment after anterior cruciate ligament reconstruction at 12months: Comparison between 3D CT and 3D MRI. A pilot study

BACKGROUND

Tunnel positioning assessment is a major issue after anterior cruciate ligament (ACL) reconstruction surgery. Historically, it used plain X-ray and, more recently, CT with 3D reconstruction. MRI is a reliable method of assessing ACL graft integrity and postoperative complications. To our knowledge, there have been no studies of efficacy in tunnel positioning assessment. The aim of this study was to assess the efficacy of 3D MRI in assessing femoral and tibial tunnel positioning after ACL reconstruction. The hypothesis was that 3D MRI sequences with reconstruction are as accurate as 3D CT for tunnel positioning assessment in ACL reconstruction.

METHODS

Twenty-two patients who underwent an arthroscopic ACL reconstruction using hamstring graft were included in a prospective study. All patients were examined on 3D CT and 3D MRI at 12months post-surgery. Tunnel positioning was assessed on both imaging systems by a musculoskeletal radiologist and an orthopedic surgeon specialized in knee arthroscopy, both blind to all clinical data.

RESULTS

No statistically significant difference was found between 3D CT and 3D MRI on coronal and sagittal reconstructions. For coronal assessment of tibial tunnel orifice, sagittal assessment of tibial tunnel orifice and sagittal assessment of femoral tunnel orifice, P-values ranged from 0.37 to 0.99, 0.051 to 0.64 and 0.19 to 0.59, respectively. For tibial and femoral tunnel angulation, P-values were respectively 0.52 and 0.29.

CONCLUSION

3D MRI is a reliable method to assess femoral and tibia tunnel positioning in ACL reconstruction, compared to 3D CT as gold standard. Indeed, in our opinion 3D MRI could in the future replace CT for ACL reconstruction assessment, concerning not only the meniscus and ligaments but also tunnel position.

LEVEL OF EVIDENCE

Level 3; comparative prospective study.

Factors That Predict Failure in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anatomic graft placement in anterior cruciate ligament (ACL) reconstruction has become the preferred technique for many surgeons. The predictive factors for graft failure in anatomic single-bundle ACL reconstruction are relatively unknown.

PURPOSE

To determine the risk factors for graft failure and the relative importance of those factors in anatomic single-bundle ACL reconstruction.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

All primary anatomic ACL reconstructions undertaken at a single institution over a 2-year period were evaluated for subjective and objective measures of graft failure. Risk factors evaluated included time since ACL rupture, age, sex, body mass index, intact or deficient medial and lateral meniscus, meniscal repair, hamstring graft size, and femoral and tibial tunnel position as assessed by 3D computed tomography (CT) scan. The significant factors predicting failure and the relative importance of those factors were determined.

RESULTS

At a median follow-up of 26 months, 123 patients were available for analysis. Ninety-seven patients underwent postoperative 3D CT for tunnel positions, including all 20 cases with graft failure. The significant predictors of graft failure were medial meniscal deficiency (hazard ratio [HR] 15.1; 95% CI, 4.7-48.5; P < .001), lateral meniscal deficiency (HR 9.9; 95% CI, 3-33; P < .001), shallow nonanatomic femoral tunnel positioning (HR 4.3; 95% CI, 1.6-11.6; P = .004), and younger patient age (HR 0.9; 95% CI, 0.9-1; P = .008).

CONCLUSION

Meniscal deficiency is the most significant factor to predict graft failure in single-bundle anatomic ACL reconstruction. Shallow nonanatomic femoral tunnel positioning and younger patient age are additional risk factors for failure, but their relative importance is less.

Influence of change of tunnel axis angle on tunnel length during double-bundle ACL reconstruction via the transportal technique

BACKGROUND

Commercially available flexible reamer and curved guide systems allow a certain degree of control over intra-articular tunnel orientation, therefore allows a wide range of intra-osseous femoral tunnel orientations, contrary to the femoral tunneling technique using a straight guide pin, which are determined by knee flexion angle. We sought to find the clinical relevance of intra-osseous femoral tunnel orientations in the respect of tunnel length. To evaluate the relationship between the tunnel axis angle in three orthogonal planes and tunnel length in the anteromedial (AM) and posterolateral (PL) femoral tunnels in patients who underwent anatomic double-bundle anterior cruciate ligament reconstruction (DB-ACLR) using the transportal (TP) technique with a 42^o curved guide.

METHODS

A total of 40 patients who underwent primary DB-ACLR with the TP technique using a curved guide were evaluated retrospectively. The tunnel axis angle in three orthogonal planes were evaluated on a three-dimensional surface model constructed using an axial computed tomography scan obtained after reconstruction. Then, correlations with tunnel length were analyzed.

RESULTS

In the AM tunnel, tunnel axis angles in the coronal (β = 0.0252, p = 0.022) and sagittal (β = 0.0168, p = 0.029) plane showed significant correlations with tunnel length, while the axial plane did not (p = 0.493) (adjusted R² = 0.801). In the PL tunnel, only tunnel axis angles in the axial plane (β = 0.0262, p = 0.008) showed a significant relationship with tunnel length (adjusted R² = 0.700).

CONCLUSION

Drilling at a higher angle in the coronal and sagittal planes in AM tunnels and at a higher angle in the axial plane in PL tunnels decreases the incidence of short femoral tunnels.

Three-Dimensional CT Evaluation of Tunnel Positioning in ACL Reconstruction Using the Single Anteromedial Bundle Biological Augmentation (SAMBBA) Technique

BACKGROUND

Remnant preservation may confer important advantages in the anterior cruciate ligament (ACL)-reconstructed knee. However, the presence of a large remnant may obscure visualization and impair the ability to correctly place tunnels during surgery.

PURPOSE

To determine whether tunnel placement during anatomic ACL reconstruction using the single anteromedial bundle biological augmentation (SAMBBA) technique is consistent and precise when a large native remnant is preserved.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Included in this study were 99 patients undergoing an ACL reconstruction during which at least 50% of the native ACL was preserved. The femoral tunnel was created using an outside-in specific guide. The tibial tunnel was positioned in the anteromedial region of the ACL footprint, and the remnant was carefully preserved while drilling and passing the semitendinosus graft through it. Postoperatively, 3-dimensional computed tomography (3D CT) was used to evaluate tunnel placement. The mean tunnel locations were calculated and the standard deviation was used to evaluate precision of positioning. Inter- and intrareader agreement were determined to assess reliability of evaluation of tunnel position.

RESULTS

The center of the femoral tunnel was positioned at a mean 19.4% (SD, 2%) of the depth of the notch and a mean 23.1% (SD, 3.5%) of the lateral wall height. The center of the tibial tunnel was positioned at a mean 36.3% (SD, 3.8%) of the anteroposterior length of the tibial plateau and at a mean 47.0% (SD, 2.7%) of the mediolateral width. The small standard deviations demonstrate that this technique allows precise tunnel placement. The tunnel positions achieved were consistent with previous anatomic studies of femoral and tibial anteromedial bundle insertion. Intra- and interobserver reliability were high.

CONCLUSION

Three-dimensional CT evaluation demonstrated that despite the presence of a large remnant, placement of femoral and tibial tunnels for anatomic ACL reconstruction using the SAMBBA technique is consistent and precise.

Anatomic ACL reconstruction: the normal central tibial footprint position and a standardised technique for measuring tibial tunnel location on 3D CT

PURPOSE

The aim of this study was to define the normal ACL central tibial footprint position and describe a standardised technique of measuring tibial tunnel location on 3D CT for anatomic single-bundle ACL reconstruction.

METHODS

The central position of the ACL tibial attachment site was determined on 76 MRI scans of young individuals. The central footprint position was referenced in the anterior-posterior (A-P) and medial-lateral (M-L) planes on a grid system over the widest portion of the proximal tibia. 3D CT images of 26 young individuals had a simulated tibial tunnel centred within the bony landmarks of the ACL footprint, and the same grid system was applied over the widest portion of the proximal tibia. The MRI central footprint position was compared to the 3D CT central footprint position to validate the technique and results.

RESULTS

The median age of the 76 MRI subjects was 24 years, with 32 females and 44 males. The ACL central footprint position was at 39 (±3 %) and 48 (±2 %), in the A-P and M-L planes, respectively. There was no significant difference in this position between sexes. The median age of the 26 CT subjects was 25.5 years, with 10 females and 16 males. The central position of the bony ACL footprint was at 38 (±2 %) and 48 (±2 %), in the A-P and M-L planes, respectively. The MRI and CT central footprint positions were not significantly different in relation to the medial position, but were different in relation to the anterior position (A-P 39 % vs. 38 %, p = 0.01). The absolute difference between the central MRI and CT reference positions was 0.45 mm.

CONCLUSIONS

The ACL's normal central tibial footprint reference position has been defined, and the technique of measuring tibial tunnel location with a standardised grid system is described. This study will assist surgeons in evaluating tibial tunnel position in anatomic single-bundle ACL reconstruction.

LEVEL OF EVIDENCE

III.

The effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in single-bundle anatomic ACL reconstruction

PURPOSE

The purpose of the current study was to investigate the potential effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in anatomic ACL reconstruction, using an ideal anatomic point as reference and evaluating postoperative tunnel placement based on 3D CT.

METHODS

An experienced ACL surgeon, using the anatomic approach for femoral tunnel placement, relying on intraarticular landmarks and remnants of the torn ACL-and novel to the fluoroscopic assist-was introduced to its use. A prospective series of patients was included where group 1 (without fluoroscopy) and group 2 (with fluoroscopy) both had postoperative CT scans so that femoral tunnel position could be evaluated and compared to an ideal tunnel centre based on anatomic studies by using the Bernard and Hertel grid.

RESULTS

Group 2, where fluoroscopy was used, had a mean femoral tunnel that was closer to the ideal anatomic centre than group 1. In the Bernard and Hertel grid, the distance in the high-low axis (y-axis) was found significantly closer (P = 0.001), whilst the deep-shallow axis (x-axis) and a total absolute distance were not significantly closer to the ideal described anatomic centre.

CONCLUSIONS

Intraoperative fluoroscopy was found effective as an aid for placing the femoral tunnel in a more accurate position, as compared to a desired anatomic centre. Although the concept of the "one-size-fits-all" approach for tunnel placement is debatable, the avoidance of grossly misplaced tunnels is the benefit of using fluoroscopy during ACL reconstruction. The authors hold that fluoroscopy is readily available, safe and easy to use and therefore a good aid in the anatomic approach for graft tunnel placement, for example, in a learning situation, in revision cases and when performing low volumes of such surgery.

LEVEL OF EVIDENCE

III.

Comparison of femur tunnel aperture location in patients undergoing transtibial and anatomical single-bundle anterior cruciate ligament reconstruction

PURPOSE

Although three-dimensional computed tomography (3D-CT) has been used to compare femoral tunnel position following transtibial and anatomical anterior cruciate ligament (ACL) reconstruction, no consensus has been reached on which technique results in a more anatomical position because methods of quantifying femoral tunnel position on 3D-CT have not been consistent. This meta-analysis was therefore performed to compare femoral tunnel location following transtibial and anatomical ACL reconstruction, in both the low-to-high and deep-to-shallow directions.

METHODS

This meta-analysis included all studies that used 3D-CT to compare femoral tunnel location, using quadrant or anatomical coordinate axis methods, following transtibial and anatomical (AM portal or OI) single-bundle ACL reconstruction.

RESULTS

Six studies were included in the meta-analysis. Femoral tunnel location was 18 % higher in the low-to-high direction, but was not significant in the deep-to-shallow direction, using the transtibial technique than the anatomical methods, when measured using the anatomical coordinate axis method. When measured using the quadrant method, however, femoral tunnel positions were significantly higher (21 %) and shallower (6 %) with transtibial than anatomical methods of ACL reconstruction.

CONCLUSION

The anatomical ACL reconstruction techniques led to a lower femoral tunnel aperture location than the transtibial technique, suggesting the superiority of anatomical techniques for creating new femoral tunnels during revision ACL reconstruction in femoral tunnel aperture location in the low-to-high direction. However, the mean difference in the deep-to-shallow direction differed by method of measurement.

LEVEL OF EVIDENCE

Meta-analysis, Level II.

Radiographic assessment of the postoperative knee

Radiologists often encounter postoperative knee radiographs lacking any adjunct clinical data which might hinder accurate image interpretation. Surgical techniques are constantly evolving with new devices being used which make it sometimes challenging for the radiologist to deduce the performed procedure and to look for associated complications. This article reviews commonly performed surgical procedures of the knee, highlights their expected postoperative radiographic appearance and describes the appearance of certain postoperative complications.

The cross-sectional shape of the fourfold semitendinosus tendon is oval, not round

BACKGROUND

The looped side of the semitendinosus tendon (ST) graft (i.e., the side inserted into the femoral tunnel during anterior cruciate ligament reconstruction) appears to be oval rather than round. The purpose of this study was to investigate the cross section of the fourfold semitendinosus tendon graft and, more specifically, the differences in pressure exerted by a rounded rectangular tunnel versus a round femoral tunnel.

METHODS

Seven STs were harvested from cadaveric knees and a fourfold ST graft was made. Aluminum cubes with round or rectangular tunnels containing four-way pressure-sensitive conductive sensors (vertically and bilaterally) were used. The area of both cubes was the same. The graft was inserted into the tunnels 15 mm from the looped edge. After measuring pressure, the graft was fixed using ultraviolet-curing acrylic resin and was cut at 7.5 mm and 15 mm from the lapel edge. The area, axes for the best fitting ellipse of the cross-section, and ellipticity of the axes were measured.

RESULTS

In the round tunnel, the mean contact pressure was 287.0 ± 136.7 gf at the bilateral sensor; there was no contact pressure detected by the vertical sensor. In the rounded rectangular tunnel, the mean contact pressure was 260.9 ± 186.4 gf at the bilateral sensor and 352.9 ± 49.5 gf at the vertical sensor. Ellipticity was 1.25 ± 0.13 at 7.5 mm, and 1.17 ± 0.07 at 15 mm from the lapel edge of the graft.

CONCLUSIONS

The cross-sectional shape of the fourfold ST graft was not round, but oval. Moreover, the rounded rectangular tunnel was more fitted to the graft than the round tunnel.

Evaluation of the semitendinosus tendon graft shift in the bone tunnel: an experimental study

PURPOSE

The purpose of this study was to measure the semitendinosus tendon graft shift at the tunnel aperture with graft bending using a simulated femoral bone tunnel.

METHODS

Eight semitendinosus tendon grafts were used in this study. The median age of the specimen was 53 years (range 46-63). After stripping excess soft tissue, the semitendinosus tendon was doubled over the loop of the EndoButton CL (Smith and Nephew Inc.). The diameter of the graft was measured using a graft-sizing tube (Smith and Nephew Inc.) and verified to be 7.0 mm. A custom-made aluminium fixture, the size was 40.0 mm(3), with 7.0-mm-diameter hole was used as a simulated femoral bone tunnel. The graft was inserted to the tunnel, and EndoButton was positioned to the outside of the tunnel on the fixture. The distal end of the graft was tensioned with 30 N at an angle of 15°, 30°, 45°, 60°, 75° that reproduced the graft bending angle during knee range of motion. The photograph of the tunnel aperture was taken at each graft bending angle using a digital camera, and the graft shift amount in the simulated tunnel was analysed using the computer software (ImageJ).

RESULTS

The amount of the graft shift significantly increased when the graft bending angle was increased (P < 0.05). The biggest shift was observed when the graft bending angle was 75° in all specimens, and the value was 1.10 mm ± 0.12.

CONCLUSION

The present study suggests that even if the femoral tunnel was created in the centre of the ACL insertion site, the graft shifted within the tunnel in the direction of the tension applied to the graft during knee range of motion. Surgeons may have to consider the graft shift within the bone tunnel as well as the tunnel position in the restoration of the native ACL anatomy.

Reliability of 3-Dimensional Computed Tomography for Application of the Bernard Quadrant Method in Femoral Tunnel Position Evaluation After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To validate whether the Bernard quadrant method, which was developed for application on simple lateral radiography, can be used with 3-dimensional computed tomography (3D CT) to localize the femoral insertion of the reconstructed anterior cruciate ligament (ACL).

METHODS

We analyzed 32 knees with ACL tears that were reconstructed using a metal interference screw for fixation at the femoral tunnel between March 2012 and May 2013. Postoperative lateral radiographs and 3D CT images were obtained 7 days after the operation. By use of the Bernard quadrant method, the location of the femoral tunnel was measured by 2 orthopaedic surgeons by locating the position of the metal interference screw using 3D CT imaging and simple lateral knee radiography. The correlation between the femoral tunnels on the 2 radiographic images was compared using the MedCalc statistical analysis program.

RESULTS

On the 3D CT image, the position of the femoral insertion of the ACL as measured by the position of the metal screw head was 36.3% ± 6.0% in the x-coordinate and 39.6% ± 9.1% in the y-coordinate compared with 37.6% ± 5.8% and 41.0% ± 11.6%, respectively, on the simple radiograph. The Pearson correlation coefficients between 3D CT and simple radiography were 0.840 for the x-coordinate and 0.858 for the y-coordinate. Intraobserver reliability and interobserver reliability for both coordinates were greater than 0.9 on 3D CT.

CONCLUSIONS

Application of the Bernard quadrant method on 3D CT showed high correlation to the originally described method using lateral radiographs and can be used reliably for localizing the reconstructed ACL.

LEVEL OF EVIDENCE

Level III, diagnostic study.

The influence of graft placement on clinical outcome in anterior cruciate ligament reconstruction

PURPOSE

the aim of the present study was to investigate the influence of graft tunnel position on both clinical outcome and instrumental knee stability in patients submitted to arthroscopic ACL reconstruction using a bone-patellar tendon-bone (BPTB) graft.

METHODS

thirty patients (24 men and 6 women) who underwent ACL reconstruction performed using an autologous bone-patellar tendon-bone graft were studied at a mean follow-up of 18 months. Clinical outcome was assessed on the basis of the Lysholm score, Tegner activity level, International Knee Documentation Committee (IKDC) subjective form and the Short Form-36. Clinical outcomes were correlated with both femoral and tibial tunnel placement measured on standard anteroposterior and lateral knee radiographs, in accordance with established guidelines.

RESULTS

tibial tunnel position on the lateral view correlated significantly with both the IKDC subjective form (r = -0.72; p<0.05) and the Lysholm score (r=-0.73; p<0.05). Tibial tunnel position on the lateral view also correlated with stability measured using a KT-1000 arthrometer at 30N of force (r=0.57; p<0.05). No correlation was found between α angle and anteroposterior (AP) laxity measured by KT-1000 arthrometer. No significant correlation was found between femoral tunnel position (on either view) and Lysholm score, IKDC score and Tegner activity level. Similarly, no correlation was found between AP laxity measured by KT-1000 arthrometer and femoral tunnel position.

CONCLUSIONS

these results suggest that the more anterior the placement of the tibial tunnel, the better the clinical outcome will be. On the basis of literature data and our findings, we discuss the hypothesis that there exists a "correct area" for tunnel placement, making it possible to obtain the best results.

LEVEL OF EVIDENCE

Level IV, case series.

Arthroscopic image distortion-part I: the effect of lens and viewing angles in a 2-dimensional in vitro model

PURPOSE

Arthroscopic images are subject to distortion, which may increase when using arthroscope lenses with greater reflecting angles and/or viewing structures at oblique angles. The purpose of this study was to determine the magnitude of image distortion experienced when using arthroscopes with different lens angles and when the line-of-sight (i.e., viewing angle) is not directly perpendicular to the target.

METHODS

A dot calibration target was captured through 0°, 30°, and 70° arthroscopes from straight (i.e., directly perpendicular) and 30° oblique viewing angles. Distortions in horizontal and vertical distances in deep (located at 87.5 % length of arthroscopic image diameter) or shallow (12.5 % diameter length) regions were calculated, from which a deformity ratio (horizontal/vertical distance) was determined.

RESULTS

From the straight viewing angle (0°), both horizontal and vertical distances were artificially reduced (i.e., <100 % magnification) in the shallow and deep regions. The deformity ratio was ~100 % in the central region, declining to ~80 % peripherally. From the oblique viewing angle (30°), magnification was below 100 % in the deep area but exceeded 100 % in the shallow area, with increasing distortion associated with increasing lens angle (0° < 30° < 70°). For all lens angles, the deformity ratio was ~50 % in the deep area but neared 100 % in the shallow region.

CONCLUSIONS

Arthroscopic image distortion in peripheral regions should be considered when using angled-lens arthroscopes, especially when the viewing angle is not straight. As viewing the femoral ACL footprint through the anterolateral portal involves using an oblique viewing angle, visualization through the anteromedial portal is recommended.

Transtibial technique versus two incisions in anterior cruciate ligament reconstruction: tunnel positioning, isometricity and functional evaluation

OBJECTIVE

To compare the transtibial and two-incision techniques for anterior cruciate ligament (ACL) reconstruction using a single band.

METHODS

A prospective and randomized study was conducted in blocks. Patients underwent ACL reconstruction by means of two techniques: transtibial (group 1: 20 patients) or two incisions (group 2: 20 patients). The radiographic positioning of the tunnel, inclination of the graft, graft isometricity and functional results (IKDC and Lysholm) were evaluated.

RESULTS

The positioning of the femoral tunnel on the anteroposterior radiograph, expressed as a mean percentage relative to the medial border of the tibial plateau, was 54.6% in group 1 and 60.8% in group 2 (p < 0.05). The positioning of the femoral tunnel on the lateral radiograph, expressed as a mean percentage relative to the anterior border of Blumensaat's line, was 68.4% in group 1 and 58% in group 2 (p < 0.05). The mean inclination of the graft was 19° in group 1 and 27.2° in group 2 (p < 0.05). The mean graft isometricity was 0.96 mm in group 1 and 1.33 mm in group 2 (p > 0.05). Group 2 had better results from the pivot-shift maneuver (p < 0.05).

CONCLUSION

The technique of two incisions allowed positioning of the femoral tunnel that was more lateralized and anteriorized, such that the graft was more inclined and there was a clinically better result from the pivot-shift maneuver. There was no difference in isometricity and no final functional result over the short follow-up time evaluated.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Cohort Study, Level III.

Knee stability, athletic performance and sport-specific tasks in non-professional soccer players after ACL reconstruction: comparing trans-tibial and antero-medial portal techniques

BACKGROUND

a wrong position of bone tunnels, in particular on the femur, is one of the most frequent causes of a failed anterior cruciate ligament (ACL) reconstruction. Several studies demonstrated that drilling the femoral tunnel through the antero-medial portal (AMP) allows a more anatomical placement on the lateral femoral condyle and higher knee stability, compared to trans-tibial (TT) technique. The aim of this study was to retrospectively evaluate two groups of soccer players operated on for ACL reconstruction according to either one of these two techniques.

METHODS

two groups of non-professional soccer players operated on for a single bundle ACL reconstruction with hamstrings autograft using either a TT (20 patients) or an AMP (23 patients) technique were retrospectively evaluated with KT-1000 arthrometer, manual pivot shift test, isokinetic test, the incremental treadmill-running test, athletic and sport specific tasks, and knee scores (IKDC, Lysholm and KOOS).

RESULTS

the AMP group showed better results at pivot shift test and KOOS, but lower flexion angles at single leg squat test. There were no differences in all the other considered outcomes.

CONCLUSIONS

the better rotational stability of the knee achieved in AMP group did not lead to significantly better clinical and functional results in our patients.

LEVEL OF EVIDENCE III TREATMENT STUDY

Case-control study.

Variability of tunnel positioning in fluoroscopic-assisted ACL reconstruction

PURPOSE

Intraoperative fluoroscopy has been proposed as a feasible method to improve the accuracy of anatomical tunnel positioning. However, it has so far not been determined, whether this technique reduces the variability of tunnel positioning in a clinical set-up. Therefore, the purpose of this study was to determine the variability of tunnel positions applying intraoperative fluoroscopy.

METHODS

Femoral and tibial tunnel positions of 112 fluoroscopic ACL reconstruction cases were determined according to validated radiological measurement methods. Mean positions, standard deviations and ranges were calculated to determine the variability of the tunnel positions. Subgroup variability analysis was performed to analyse cases in which tunnel positions were corrected.

RESULTS

Applying intraoperative fluoroscopy, the variability of tunnel positions was found to be 3 % at the femur (range 15.4 %) and 2.3 % at the tibia (9.7 %). In 34 cases (30.0 %), non-satisfactory tunnel positions were identified and could be corrected achieving more accurate positions regarding to radiological parameters (14× femur, 16× tibia, 4× femur and tibia).

CONCLUSIONS

The results of the presented study indicate that intraoperative fluoroscopy allows to identify non-accurate tunnel positions regarding to radiological criteria. The determined low variability indicates that fluoroscopic-based ACL reconstruction can be recommended as a feasible, easy and effective adjunct that enables surgeons to create more consistent and reliable tunnel positions in ACL reconstruction.

LEVEL OF EVIDENCE

IV.

Variability of landmark acquisition affects tunnel calculation in image-free ACL navigation

PURPOSE

The purpose of this study was to determine the inter- and intraobserver variability of intraarticular landmark identification for tunnel position calculation in image-free anterior cruciate ligament (ACL) navigation.

METHODS

In a test/retest scenario, thirteen experienced ACL surgeons (>50 reconstructions year) experienced in image-free ACL navigation were asked to identify the landmarks required for image-free ACL navigation in the same cadaver knee. Landmark positions were registered using a fluoroscopic ACL navigation system. Positions were determined using validated radiological measurement methods. For variability analysis, mean positions, deviations between the test/retest positions, standard deviations (SD) and range were calculated.

RESULTS

Interobserver analysis showed a mean variability (SD) for the tibial landmark positions of 3.0 mm with deviations of up to 24.3 mm (range). Mean femoral landmark variability was 2.9 mm (SD) with deviations of up to 11.3 mm (range). Intraobserver analysis showed a tibial reproducibility of 2.2 mm (SD 2.0 mm; range 10.9 mm) and a femoral of 1.9 mm (SD 1.9 mm; range 10.4 mm).

CONCLUSION

The data of the presented study suggest that a considerable inter- and intraobserver variability in intraarticular landmark identification exists. Reasonable ranges were found that have to be considered as a potential risk for miscalculation of tunnel positions in image-free ACL reconstruction.

CLINICAL RELEVANCE

Landmark acquisition affects tunnel calculation in image-free ACL.

LEVEL OF EVIDENCE

IV.

Can we use intraoperative femoral tunnel length measurement as a clue for proper femoral tunnel placement on coronal plane during ACL reconstruction?

INTRODUCTION

Successful anterior cruciate ligament (ACL) reconstruction is dependent on correct placement of both tibial and femoral tunnels. The purpose of this study is to investigate whether we can use intraoperative femoral tunnel length measurement to estimate the correct femoral tunnel placement on coronal plane.

METHODS

This prospective study comprised 164 consecutive patients who underwent ACL reconstruction surgery. Transtibial or anteromedial portal technique is used for drilling the femoral tunnels. The length of the femoral tunnel was measured during the operation. The femoral tunnel coronal plane angle was calculated on the postoperative tunnel radiographs. A statistical comparison was made of the lengths of the tunnel, the techniques used drilling and the femoral tunnel angles.

RESULTS

The far anteromedial portal was used in 81 (49%) cases and the transtibial technique in 83 (51%) cases. The mean femoral tunnel length was 42 ± 6.4 mm and the mean femoral tunnel coronal angle was 41.1° ± 11.6. The tunnel angle in the transtibial technique was determined as significantly low compared to the far anteromedial portal technique (32.6°:49.8°) and the tunnel length was significantly longer (45.8:38.1 mm) (p < 0.001). In the statistical analysis, it was found that a patient with a tunnel length of 41 mm and above had a 92.1% likelihood of femoral tunnel angle below 45°.

CONCLUSION

Femoral tunnel length can be used as a clue for intraoperative evaluation of the femoral tunnel position. If the femoral tunnel length is greater than 41 mm, the coronal plane orientation of the femoral tunnel will be improper and not at a desired position.

[Knee laxity in anterior cruciate ligament reconstruction : The influence of graft rotation using interference screw fixation]

BACKGROUND

The use of interference screws for femoral graft fixation in anterior cruciate ligament (ACL) reconstruction with hamstring grafts can result in rotation of the graft around the screw leading to changes in the final position of the graft within the bone tunnel.

MATERIAL AND METHODS

In a prospective study 107 patients (54 right and 53 left knees) underwent ACL reconstruction with a hamstring tendon autograft. Femoral fixation of the graft was performed with a standard right-thread screw in all cases. Patients were assessed at 6 months postoperatively with the international knee documentation committee (IKDC) standard evaluation including instrumented laxity measurements and the results were compared between right and left knees.

RESULTS

A significantly higher postoperative anterior laxity was observed in left knees with a negative Lachman test in only 64 % of the cases compared with 87 % in the group of right knees. Accordingly, instrumented laxity measurements of the reconstructed knee compared with the contralateral knee revealed significant differences between left and right knees (left knees 1.8±1.2 mm and right knees 1.0±1.4 mm).

CONCLUSIONS

This study demonstrates the importance of femoral graft positioning and its sensitivity to multiple influencing factors. The use of standard right-thread interference screws for femoral graft fixation in the mirrored situation of right and left knees may produce a systematic error in ACL reconstruction. Due to a possible rotation of the graft around the screw, the final position of the transplant may vary thus leading to significant changes in anterior translation of the operated knee.

Femoral marrow cavity bone harvesting used for arthroscopic refilling of misplaced or enlarged bone tunnels in revision ACL surgery: an arthroscopically supported technique with antegrade intramedullary bone harvesting by a reamer-irrigator-aspirator (RIA) system

PURPOSE

In anterior cruciate ligament (ACL) revision surgery, refilling of misplaced or enlarged tunnels frequently requires bone harvesting from the iliac crest. Unfortunately, donor-site pain displays a relevant complication. In order to optimize patients' comfort, we developed a procedure combining minimally invasive intramedullary bone harvesting from the femur with arthroscopic tunnel refilling.

METHODS

Patients with ACL reconstruction failure that were not eligible for one-step revision surgery but required tunnel refilling prior to the next ACL reconstruction were enrolled prospectively. Cancellous bone was harvested intramedullarily from the ipsilateral femur using the reamer-irrigator-aspirator system in a minimally invasive manner. Afterwards, the femoral and tibial tunnels were arthroscopically refilled using cones and push rods. Computer tomography (CT) analyses were carried out before and after the filling procedure. Pain levels were assessed during the entire follow-up. Patients undergoing iliac crest bone harvesting for other reasons served as a control group. Finally, the quality of the newly formed bone stock was evaluated in the subsequent ACL reconstruction procedure.

RESULTS

Five patients were included during a 6-month period. Prior to refilling, tunnel analysis revealed a mean tunnel volume of 7.9 cm(3) at the femur [SD ± 5.3 cm(3)] and of 6.7 cm(3) [SD ± 5.1 cm(3)] at the tibia. The CT analyses further revealed that graft failure was predominantly caused by tunnel misplacement. Post-operatively, pain levels due to intramedullary bone harvesting were significantly lower compared to iliac crest bone harvesting at every analysed time point. Three to five months after tunnel filling, CT analyses showed sufficiently incorporated bone stocks with filling rates of 75 % femoral and 94 % tibial. ACL revision surgery was performed 4-5 months after tunnel filling without any complication.

CONCLUSION

Intramedullary bone harvesting from the ipsilateral femur combined with arthroscopic refilling of the bone tunnels ensures a high-quality bone stock for further ACL reconstruction. The clinical relevance is shown by the feasibility of this technique and the significantly reduced pain levels during post-operative recovery.

Three-dimensional computed tomography evaluation of anterior cruciate ligament footprint for anatomic single-bundle reconstruction

PURPOSE

Femoral and tibial footprint coordinates have been well studied in double-bundle anterior cruciate ligament (ACL) reconstruction. However, in a single-bundle reconstruction approach, the central coordinate of femoral and tibial footprints have not been determined. The purpose of this study was to describe the central point locations of the ACL footprints visualized by three-dimensional computed tomography (3D CT) images and analysed by the quadrant method.

METHODS

Eight cadaveric knees were dissected, and the central points of ACL femoral and tibial footprints were marked and analysed using 3D CT images.

RESULTS

In the present study, the means (and standard deviation) of ACL femoral footprint dimensions were in the ventral-dorsal plane and in the cranial-caudal plane 9.4 ± 0.8 and 15.6 ± 0.9 mm, respectively. In the tibial side, the means of ACL footprint dimensions were in the anterior-posterior and in the medial-lateral 18.5 ± 1.9 and 15.5 ± 1.0 mm, respectively. In the tomographic analyses, the means of femoral central location coordinates in the ventral-dorsal (y) and in the cranial-caudal (x) axes were 35.3 ± 4.5 and 30.0 ± 1.6 %, respectively. The means of tibial central location coordinates were in the anterior-posterior (y) and in the medial-lateral (x) axes, respectively: 40.5 ± 5.3 and 50.2 ± 1.3 %, respectively.

CONCLUSIONS

These computed tomographic coordinates might help future studies as a reference on ACL single-bundle anatomic reconstruction, with respect to the management of ACL revision surgery or in symptomatic patients after ACL reconstruction. Improvements in three-dimensional image acquisition could facilitate its intraoperative applicability in the coming years.

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.

Trans-tibial guide wire placement for femoral tunnel in single bundle anterior cruciate ligament reconstruction

BACKGROUND

Femoral tunnel location is of critical importance for successful outcome of ACL reconstruction. The aim was to study the femoral tunnel created by placing free hand guide wire through tibial tunnel, using the toggle of the guide wire in the tibial tunnel to improve femoral tunnel location.

MATERIALS AND METHODS

30 cases of a single bundle quadrupled hamstring graft anterior cruciate ligament reconstruction by trans-tibial free hand femoral tunnel creation is studied in this prospective study. The side to side play of the guide wire in the tibial tunnel was used to improve the tunnel location on femoral wall. The coronal angle of the femoral tunnel was measured on the anteroposterior radiograph. The femoral tunnel location on the lateral radiograph of the knee was recorded according to Amis method. Lysholm scoring was done preoperative and at each follow up. Assessment of laxity was done by Rolimeter (Aircast(™)) and pivot shift test.

RESULTS

The mean coronal angle of the femoral tunnel in postoperative radiograph was 47°. In lateral radiograph, the femoral tunnel was found to be >60% posterior on Blumensaat line in 67% cases (n = 20) and in the 33% cases (n = 10) it was anterior. The mean Lysholm score improved from 74.6 preoperative to 93.17 postoperative with no objective evidence of laxity.

CONCLUSION

The free hand trans-tibial creation of the femoral tunnel leads to satisfactory coronal obliquity, but it is difficult to recreate anatomic femoral tunnel by this method as the tunnel is consistently anterior in the sagittal plane.

Variability of tunnel positioning in ACL reconstruction

INTRODUCTION

Since tunnel positioning is one of the key factors in anterior cruciate ligament (ACL) reconstruction and the variability of tunnel positioning in ACL reconstruction has so far never been analyzed, the objective of this study was to determine the inter- and intra-observer variability of tibial and femoral tunnel positioning in ACL reconstruction.

MATERIALS AND METHODS

In an operating room setup, 13 surgeons were asked to identify the tunnel positions in one and the same ACL-deficient cadaver knee. Using a fluoroscopic based ACL navigation system, tunnel positions were digitally measured in a test/re-test scenario. For variability analysis mean positions, standard deviations and range were calculated as well as differences between test/re-test positions.

RESULTS

The intraobserver analysis showed a tibial variability of 3.3 mm (SD 2.1, range 7.5 mm) and a femoral variability of 2.0 mm (SD 1.6 mm, range 6.8 mm). The interobserver variability of the tibial tunnel positions was 3.2 mm (SD) with a range of 18.3 mm and a femoral variability of 3.7 mm (SD) with a range of 13.2 mm.

CONCLUSIONS

This study demonstrates that a reasonable inter- and intra-observer variability in ACL tunnel positioning exists even among experienced surgeons. Although deviations of 2-3 mm may seem to be acceptable at first sight, a range of up to 18.3 mm indicates that outliers exist, which can cause graft failure. More reliable reconstruction techniques should be developed to reduce the variability in tunnel positioning.

The morphometry of soft tissue insertions on the tibial plateau: data acquisition and statistical shape analysis

This study characterized the soft tissue insertion morphometrics on the tibial plateau and their inter-relationships as well as variabilities. The outlines of the cruciate ligament and meniscal root insertions along with the medial and lateral cartilage on 20 cadaveric tibias (10 left and 10 right knees) were digitized and co-registered with corresponding CT-based 3D bone models. Generalized Procrustes Analysis was employed in conjunction with Principal Components Analysis to first create a geometric consensus based on tibial cartilage and then determine the means and variations of insertion morphometrics including shape, size, location, and inter-relationship measures. Step-wise regression analysis was conducted in search of parsimonious models relating the morphometric measures to the tibial plateau width and depth, and basic anthropometric and gender factors. The analyses resulted in statistical morphometric representations for Procrustes-superimposed cruciate ligament and meniscus insertions, and identified only a few moderate correlations (R2: 0.37-0.49). The study provided evidence challenging the isometric scaling based on a single dimension frequently employed in related morphometric studies, and data for evaluating cruciate ligament reconstruction strategies in terms of re-creating the native anatomy and minimizing the risk of iatrogenic injury. It paved the way for future development of computer-aided personalized orthopaedic surgery applications improving the quality of care and patient safety, and biomechanical models with a better population or average representation.

Radiological analysis on femoral tunnel positioning between isometric and anatomical reconstructions of the anterior cruciate ligament

OBJECTIVE

the aim of this study was to radiologically evaluate the femoral tunnel position in anterior cruciate ligament (ACL) reconstructions using the isometric and anatomical techniques.

METHODS

a prospective analytical study was conducted on patients undergoing ACL reconstruction by means of the isometric and anatomical techniques, using grafts from the knee flexor tendons or patellar tendon. Twenty-eight patients were recruited during the immediate postoperative period, at the knee surgery outpatient clinic of FCMMG-HUSJ. Radiographs of the operated knee were produced in anteroposterior (AP) view with the patient standing on both feet and in lateral view with 30° of flexion. The lines were traced out and the distances and angles were measured on the lateral radiograph to evaluate the sagittal plane. The distance from the center of the screw to the posterior cortical bone of the lateral condyle was measured and divided by the Blumensaat line. In relation to the height of the screw, the distance from the center of the screw to the joint surface of the lateral condyle of the knee was measured. On the AP radiograph, evaluating the coronal plane, the angle between the anatomical axis of the femur and a line traced at the center of the screw was measured.

RESULTS

with regard to the p measurement (posteriorization of the interference screw), the tests showed that the p-value (0.4213) was greater than the significance level used (0.05); the null hypothesis was not rejected and it could be stated that there was no statistically significant difference between the anatomical and isometric techniques. With regard to the H measurement (height of the screw in relation to the lower cortical bone of the knee), the p-value observed (0.0006) was less than the significance level used (0.05); the null hypothesis was rejected and it could be stated that there was a statistically significant difference between the anatomical and isometric techniques. It can be concluded that the latter difference occurred because the isometric technique generated greater values for the H measurement than the anatomical technique. With regard to the MED variable (position of the screw on the AP radiograph), the observed p-value (0.000) was less than the significance level (5%); the null hypothesis was rejected and it could be stated with 95% confidence that there was a significant difference between the anatomical and isometric techniques.

CONCLUSIONS

there were statistically significant differences in the radiological evaluations of the femoral tunnel, both in the sagittal and in the coronal plane, between the ACL reconstruction techniques.

The influence of femoral tunnel position in single-bundle ACL reconstruction on functional outcomes and return to sports

PURPOSE

The purpose of this study was to radiographically investigate the influence of femoral tunnel placement in ACL reconstruction on early outcomes and return to sports due to anatomic and nonanatomic positioning.

METHODS

A prospective study was conducted from 2008 to 2010, with 86 athletes who underwent ACL reconstruction between anteromedial (AM) footprint and high AM position. Knee functional outcomes (IKDC objective and subjective, Tegner score, and Lysholm scale) return to sports and complications were analyzed at 6- and 12-month follow-up.

RESULTS

At follow-up, it was observed that tunnel projection along Blumensaat's line was correlated with functional outcomes on Tegner scale (at 6 and 12 months) and IKDC subjective (at 12 months). There was a significant difference in mean tunnel projection along Blumensaat's line when analyzing return to sports (73 ± 1.4 and 79 ± 1.7 %, respectively, for projections on return vs. no return to sports, p = 0.02) and complications (73 ± 1.3 vs. 78 ± 1.6 %, respectively, for projections on no complications vs. complications, p = 0.03). No differences were stated on coronal view. These correlations between tunnel positioning on functional outcomes could not be explained by demographic or baseline characteristics.

CONCLUSION

The clinical relevance of this study is that tunnel positioning along AM footprint and high AM position represented by tunnel projection along Blumensaat's line is associated with early return to sports on previous Tegner level and better functional outcome in athletes.

How to read post-operative radiographs and CT scans after single-bundle anterior cruciate ligament reconstruction

Reconstruction of the anterior cruciate ligament (ACL) is a well-established surgical procedure. However, post-operative imaging in the early phase is not routinely performed. The rationale for performing such imaging is to provide a baseline examination for future controls, to provide immediate feedback to surgeons regarding tunnel placement, and to assess placement of fixation devices. The purpose of this paper is to enable the reader to accurately read post-operative radiographs and CT scans after single-bundle ACL reconstruction.