Tibial Tunnel Position Research Articles

3D CT analysis of femoral and tibial tunnel positions after modified transtibial single bundle ACL reconstruction with varus and internal rotation of the tibia

IntroductionWe analyzed the location of femoral and tibial tunnels by three-dimensional (3D) CT reconstruction images after modified transtibial single bundle (SB) anterior cruciate ligament (ACL) reconstruction, creating a femoral tunnel with varus and internal rotation of the tibia. Material and methodsData from 50 patients (50 knees) analyzed by 3D CT after modified transtibial SB ACL reconstructions were evaluated. 3D CT images were analyzed according to the quadrant method by Bernard at the femur and the technique of Forsythe at the tibia. ResultsThe mean distance of the femoral tunnel center locations parallel to the Blumensaat's line was 29.6%±1.9% along line t measured from the posterior condylar surface. The mean distances perpendicular to the Blumensaat's line were 37.9%±2.5% along line h measured from the Blumensaat's line. At the tibia, the mean anterior-to-posterior distance for the tunnel center location was 37.8%±1.2% and the mean medial-to-lateral distance was 50.4%±0.9%. DiscussionThe femoral and tibial tunnels after modified transtibial SB ACL reconstruction creating a femoral tunnel with varus and internal rotation of the tibia (figure-of-4 position) were located between the anatomical anteromedial and posterolateral footprints.

SPECT/CT tracer uptake is influenced by tunnel orientation and position of the femoral and tibial ACL graft insertion site

SPECT/CT is a hybrid imaging modality, which combines a 3D scintigraphy (SPECT) and a conventional computerised tomography (CT). SPECT/CT allows accurate anatomical localisation of metabolic tracer activity. It allows the correlation of surgical factors such as tunnel position and orientation with mechanical alignment, clinical outcome and biological factors. The purpose of this study was to investigate whether the SPECT/CT tracer uptake (intensity and distribution) correlates with the stability and laxity of the knee joint and the position and orientation of the tibial and femoral tunnels in patients after anterior cruciate ligament (ACL) reconstruction. A consecutive series of knees (n=66), with symptoms of pain and/or instability after ACL reconstruction were prospectively evaluated using clinical examination and 99mTc-HDP-SPECT/CT. Clinical laxity testing was performed using the Rolimeter (Ormed, Freiburg, Germany) including Lachman testing (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), anterior drawer test (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), pivot shift test (positive versus negative) and patient-based subjective instability (yes versus no). For analysis of SPECT/CT tracer uptake a previously validated SPECT/CT localisation scheme consisting of 17 tibial, nine femoral and four patellar regions on standardised axial, coronal, and sagittal slices was used. The tracer activity on SPECT/CT was localised and recorded using a 3D volumetric and quantitative analysis software. Mean, standard deviation, minimum and maximum of grading for each area of the localisation scheme were recorded. The position and orientation of the tibial and femoral tunnel was assessed using a previously published method on 3D-CT. Correlation of instability, pivot shift as well as clinical laxity testing with 99mTc-HDP-SPECT/CT tracer uptake intensity and distribution showed no significant correlation. 99mTc-HDP-SPECT/CT tracer uptake correlated significantly with the position and orientation of the ACL graft. A more horizontal femoral graft position showed significantly increased tracer uptake within the superior and posterior femoral regions. A more posteriorly-placed femoral insertion site showed significantly more tracer uptake within the femoral and tibial tunnel regions. A more vertical or a less medial tibial tunnel orientation showed significant increased uptake within the tibial and femoral tunnel regions. A more anterior tibial tunnel position showed significantly more tracer uptake in the femoral and tibial tunnel regions as well as the entire tibiofemoral joint. SPECT/CT tracer uptake intensity and distribution showed a significant correlation with the femoral and tibial tunnel position and orientation in patients with symptomatic knees after ACL reconstruction. No correlation was found with stability or clinical laxity. SPECT/CT tracer uptake distribution has the potential to give us important information on joint homeostasis and remodelling after ACL reconstruction. It might help to predict ACL graft failure and improve our surgical ACL reconstruction technique in finding the optimal tunnel and graft position and orientation.

Arthroscopic Agreement Among Surgeons on Anterior Cruciate Ligament Tunnel Placement

Background: Little is known about surgeon agreement and accuracy using arthroscopic evaluation of anterior cruciate ligament (ACL) tunnel positioning. Purpose: To investigate agreement on ACL tunnel position evaluated arthroscopically between operating surgeons and reviewing surgeons. We hypothesized that operating and evaluating surgeons would characterize tunnel positions significantly differently. Study Design: Controlled laboratory study. Methods: Twelve surgeons drilled ACL tunnels on 72 cadaveric knees using transtibial (TT), medial portal (MP), or 2-incision (TI) techniques and then completed a detailed assessment form on tunnel positioning. Then, 3 independent blinded surgeon reviewers each arthroscopically evaluated tunnel position and completed the assessment form. Statistical comparisons of tunnel position evaluation between operating and reviewing surgeons were completed. Three-dimensional (3D) computed tomography (CT) scans were performed and compared with arthroscopic assessments. Arthroscopic assessments were compared with CT tunnel location criteria. Results: Operating surgeons were significantly more likely to evaluate femoral tunnel position (92.6% vs 69.2%; P = .0054) and femoral back wall thickness as “ideal” compared with reviewing surgeons. Tunnels were judged ideal by reviewing surgeons more often when the TI technique was used compared with the MP and TT techniques. Operating surgeons were more likely to evaluate tibial tunnel position as ideal (95.5% vs 57.1%; P < .0001) and “acceptable” compared with reviewers. The ACL tunnels drilled using the TT technique were least likely to be judged as ideal on the tibia and the femur. Agreement among surgeons and observers was poor for all parameters (κ = −0.0053 to 0.2457). By 3D CT criteria, 88% of femoral tunnels and 78% of tibial tunnels were placed within applied criteria. Conclusion: Operating surgeons are more likely to judge their tunnels favorably than observers. However, independent surgeon reviewers appear to be more critical than results of 3D CT imaging measures. When subjectively evaluated arthroscopically, the TT technique yields more subjectively poorly positioned tunnels than the TI and MP techniques. Surgeons do not agree on the ideal placement for single-bundle ACL tunnels. Clinical Relevance: This study demonstrates that surgeons do not currently uniformly agree on ideal single-bundle tunnel placement and that the TT technique may yield more poorly placed tunnels.

The use of intra-operative fluoroscopy for tibial tunnel placement in anterior cruciate ligament reconstruction.

ObjectivesOur aim was to assess the use of intra-operative fluoroscopy in the assessment of the position of the tibial tunnel during reconstruction of the anterior cruciate ligament (ACL).MethodsBetween January and June 2009 a total of 31 arthroscopic hamstring ACL reconstructions were performed. Intra-operative fluoroscopy was introduced (when available) to verify the position of the guidewire before tunnel reaming. It was only available for use in 20 cases, due to other demands on the radiology department. The tourniquet times were compared between the two groups and all cases where radiological images lead to re-positioning of the guide wire were recorded. The secondary outcome involved assessing the tibial interference screw position measured on post-operative radiographs and comparing with the known tunnel position as shown on intra-operative fluoroscopic images.ResultsOf the 20 patients treated with fluoroscopy, the imaging led to repositioning of the tibial guide wire before reaming in three (15%). The mean tourniquet time with intra-operative fluoroscopy was 56 minutes (44 to 70) compared with 51 minutes (42 to 67) for the operations performed without. Six patients (30%) had post-operative screw positions that were > 5% more posterior than the known position of the tibial tunnel.ConclusionIntra-operative fluoroscopy can be effectively used to improve the accuracy of tibial tunnel positions with minimal increase in tourniquet time. This study also demonstrates the potential inaccuracy associated with plain radiological assessment of tunnel position.

Clinical and Second-Look Arthroscopic Study Comparing 2 Tibial Landmarks for Tunnel Insertions During Double-Bundle ACL Reconstruction With a Minimum 2-Year Follow-up

Background: Few studies have reported the clinical results of tibial tunnel placement during double-bundle anterior cruciate ligament (ACL) reconstruction. It is important to recognize arthroscopic tibial landmarks during this procedure. Hypothesis: During arthroscopic double-bundle ACL reconstruction, anterior tibial landmarks such as the intermeniscal (transverse) ligament and the Parsons knob for the anteromedial (AM) tunnel provide better knee stability and clinical outcomes than do posterior tibial landmarks such as the fovea anterior to the tibial intertubercle ridge for the posterolateral (PL) tunnel. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 121 patients underwent primary unilateral double-bundle ACL reconstructions using autogenous medial hamstring tendons. Fifty-nine patients from December 2008 through July 2009 underwent reconstructions using posterior tibial landmarks (PL group), and 62 patients from August 2009 through February 2010 underwent reconstructions using anterior tibial landmarks (AM group). Forty-seven patients (follow-up rate, 79.7%) in the PL group and 52 patients (follow-up rate, 83.9%) in the AM group underwent second-look arthroscopy and clinical evaluations under anesthesia at 1 year postoperatively and 3-dimensional computed tomography (3-D CT) evaluations at 3 weeks postoperatively. Results: Lachman test results indicated no significant differences, and pivot-shift test results were significantly lower in the AM group (P = .007). Mean side-to-side differences using the Telos device at 130 N were significantly lower in the AM group (1.4 ± 1.6 mm) compared with the PL group (2.4 ± 2.5 mm) (P = .012). Results for lack of extension were not significantly different, while those for lack of flexion were significantly better in the AM group than in the PL group (P = .036). No significant differences were observed in the Lysholm scores between the groups. In measurements of the tibial tunnel position by 3-D CT, with regard to anteroposterior depth, the AM bundle of the PL group was 41.6% ± 7.4% and the AM group was 29.1% ± 5.3% (P < .001), and the PL bundle of the PL group was 55.6% ± 7.7% and the AM group was 46.4% ± 5.8% (P < .001). No significant differences were found in mediolateral width. In second-look arthroscopy, there were significant differences with respect to the synovial cover with regard to the AM bundle (P = .024). Conclusion: Patients in the AM group showed better knee stability and range of motion than those in the PL group. Transverse ligaments and Parsons knobs proved to be useful landmarks during ACL reconstruction.

How Isometric Are the Anatomic Femoral Tunnel and the Anterior Tibial Tunnel for Anterior Cruciate Ligament Reconstruction?

The purpose of this study was to evaluate the isometry of an anatomic femoral tunnel and anterior tibial tunnel positions. Tibial tunnels were made at 2 different locations in 10 cadaveric knees: the conventional tunnel and a more anterior position. Three-dimensional computed tomography (CT) scanning was then performed at 0°, 30°, 60°, 90°, and 120°. After removal of the anterior cruciate ligament from its femoral attachment, the 2 different femoral tunnels were marked at (1) the vertical femoral tunnel point and (2) the anatomic femoral tunnel point. After scans were repeated for coordinate transformation, the change in length between the tunnels was calculated with imaging software (OsiriX, version 3.2; Apple, Cupertino, CA) and the center of rotation for the femoral tunnels was calculated with a least squares fitting algorithm. The conventional tibial tunnel-vertical femoral tunnel combination showed the least excursion as knee flexion angle changed. The vertical femoral tunnel combination groups showed a trend toward increasing length as the knee flexion angle increased. In contrast, the anatomic femoral tunnel combination groups displayed a trend toward decreased length with increasing knee flexion. At less than 30° of flexion, the tibial anterior-anatomic femoral tunnel showed the least excursion. The anatomic femoral tunnel was nonisometric, and the differences in isometry for each tunnel type were explained primarily by differences in relations between the centers of rotation of tunnels and tunnel position. When a femoral anatomic tunnel is chosen for anterior cruciate ligament reconstruction, the anterior tibial tunnel offers greater isometric benefits than the conventional tibial tunnel, especially in near full extension. The distance between anatomic femoral and tibial tunnels is greatest in full extension and decreases with flexion. This would result in graft laxity. The surgeon should give consideration to a more anterior tibial tunnel position, which shows less excursion in early flexion.

Single photon emission computerized tomography and conventional computerized tomography (SPECT/CT) for evaluation of patients after anterior cruciate ligament reconstruction: a novel standardized algorithm combining mechanical and metabolic information

The purpose of this study was to introduce a novel standardized algorithm using SPECT/CT, which promises the potential combined assessment of the biology of the joint in particular the bone-graft-fixation complex and the 3D tunnel placement in patients after ACL reconstruction. Its clinical application and inter- and intra-observer reliability should be critically evaluated. A novel SPECT/CT localization scheme consisting of 13 tibial, 9 femoral and 4 patellar regions on standardized axial, coronal and sagittal slices is proposed. The tracer activity on SPECT/CT was localized and recorded in 25 consecutive patients using a 3D volumetric and quantitative analysis software. The inter- and intra-observer reliability was assessed for localization and tracer activity. The tunnel position was assessed in 3D-CT using standardized frames of reference. The inter- and intra-observer reliability (OR) of the measured distances were calculated (ICC). The localization scheme for tracer uptake analysis was useful and easily applicable in all 25 knees. It showed very high inter-OR and intra-ORs for all regions (ICC > 0.80). Tibial and femoral tunnel position measurements showed strong agreement between the readings of the two observers; the ICCs for the position, angulation, length and entry point of the femoral tunnel were >0.88 (intra-OR) and >0.86 (inter-OR). The ICC for the position of the tibial tunnel (angulation, length and entry point) was >0.79 (intra-OR) and >0.74 (inter-OR). The SPECT/CT algorithm presented is highly reliable and clinically feasible. Combining the 3D-mechanical information on tunnel placement and attachment areas and the 3D metabolic data will be helpful in evaluating patients with pain after ACL reconstruction.

Difference in Graft Maturity of the Reconstructed Anterior Cruciate Ligament 2 Years Postoperatively

Background: Currently, there is an ongoing debate regarding the optimal graft choice between autograft and allograft tendons in reconstruction of the anterior cruciate ligament (ACL). It has been reported that allograft tendons have a slower onset and rate of revascularization compared with autograft tendons. Hypothesis: Allograft tendons might have inferior graft maturity compared with autograft tendons in ACL reconstruction at 2 years postoperatively. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 52 participants with ACL reconstruction were recruited in this study, including 30 using allograft tendons and 22 using autograft tendons. All of them had unilateral ACL reconstruction and were followed up using 3.0-T magnetic resonance imaging (MRI) at least 2 years postoperatively. Clinical examination was performed on the same day when the MRI examination was performed, including subjective functional examinations (International Knee Documentation Committee [IKDC] and Tegner Lysholm Knee Scoring Scale [TLKS]) and physical examinations (anterior drawer test and Lachman test). Four measurements based on MRI were focused on graft orientation (including tibial tunnel position and graft angles), the edematous condition of the graft, intra-articular graft width at different sites, and signal intensity of the ACL graft using the signal/noise quotient (SNQ) from a region of interest analysis. Differences in each measurement were compared between the allograft group and the autograft group. Results: All the participants returned to normal sports activities at the follow-up time point, as all of them acquired full functional strength and stability. There was no significant difference between the autograft and the allograft group with respect to IKDC or TLKS score. The knees in both of the groups were confirmed stable by physical examination before MRI. On MRI measurements, the allograft group displayed no significant difference in graft orientation compared with the autograft group (P > .05). Moreover, there was also no significant difference between allograft group and autograft group in graft width of the distal site (P > .05), middle site (P > .05), and proximal site (P > .05). However, the mean SNQ value of the allograft group was significantly higher than that of the autograft group in the distal site (6.54 ± 6.58 vs 2.98 ± 5.48; P = .0173), the middle site (7.21 ± 6.31 vs 3.56 ± 4.62; P = .0149), and the proximal site (6.61 ± 8.08 vs 2.45 ± 8.12; P = .0018). Conclusion: The allograft group had a significantly higher SNQ value compared with the autograft group in this study, indicating that allograft tendons might have inferior graft maturity than autograft tendons in ACL reconstruction at 2 years postoperatively.

Long-term results of arthroscopically assisted anatomical single-bundle anterior cruciate ligament reconstruction using patellar tendon autograft: are there any predictors for the development of osteoarthritis?

The primary purpose of our study was to analyse the long-term outcome of patients treated for anterior cruciate ligament (ACL) tears by anatomical single-bundle ACL reconstruction with patellar tendon autograft. The secondary purpose was to identify predictive factors for good outcome and occurrence of osteoarthritis. Sixty-three patients (m:f = 54:9; mean age at surgery, 27 ± 7 years) treated by ACL reconstruction were evaluated with a mean follow-up of 16 ± 1 years using IKDC2000, the SF36, Lysholm and Tegner score, Knee Society score, visual analogue scale for pain and satisfaction and KOOS. The femoral tunnel position was evaluated according to Sommer. It was also assessed in percentage of the Blumensaat line and the tibial tunnel position in percentage of the total anterior-posterior plateau length. The extent of osteoarthritis was graded according to the Kellgren-Lawrence score. The total IKDC2000 was normal in 20 (32 %), nearly normal in 29 (46 %), abnormal in 12 (19 %) and severely abnormal in 3 (5 %) of patients. The mean total SF-36 was 89 ± 13, the Lysholm score 95 ± 12, the Knee Society score 191 ± 16 and the total KOOS 84 ± 19. The Tegner score decreased from pre-injury 7(4-10) to 6 (2-10) at follow-up. The Kellgren-Lawrence score was normal in 17 (27 %), suspected osteoarthritis in 25 (40 %), minimal osteoarthritis in 5 (8 %), moderate osteoarthritis in 9 (14 %) and severe osteoarthritis in 3 patients (5 %). The femoral tunnel was in zone A in 43 patients (68 %), in zone B in 16 (25 %) and in zone C in 4 patients (7 %). The femoral tunnel position in percentage of the Blumensaat line was 49 ± 3 (range, 44-57), and the tibial tunnel position in percentage of the total anterior-posterior plateau length was 32 ± 6 (range, 21-46). Patients with meniscal lesion at the time of ACL tear showed significantly less favourable outcomes than those without. Patients treated by the proposed ACL reconstruction technique showed on average good to excellent long-term results. A meniscal lesion at the time of ACL tear was highly predictive for less favourable outcome.

Long-Term Results of Anterior Cruciate Ligament Reconstruction Using Bone–Patellar Tendon–Bone: An Analysis of the Factors Affecting the Development of Osteoarthritis

To evaluate the clinical outcomes and incidence of knee osteoarthritis (OA) and the factors associated with the onset of OA in the 3 compartments of the knee joint separately after anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone autograft. Clinical and radiologic assessments were obtained from 117 patients (80.1%). At follow-up, knee function was evaluated with the Lysholm score, Hospital for Special Surgery (HSS) score, Tegner score, and International Knee Documentation Committee (IKDC) 2000 forms. We also evaluated stability and donor-site morbidity. On the follow-up radiographs, OA was assessed by IKDC grading. The factors affecting the onset of OA in the 3 compartments of the knee joint were evaluated. The mean follow-up period was 10.3 ± 1.0 years. The mean Lysholm and HSS scores significantly increased at final follow-up (P < .001). The mean IKDC subjective score was 90.6, and 93.9% of patients had grade A or grade B knees on the objective evaluation. The mean side-to-side difference measured by KT-2000 arthrometer (MEDmetric, San Diego, CA) was 1.6 ± 1.7 mm, with 82.0% of patients showing a difference of less than 3 mm. Discomfort from knee walking on hard ground and skin numbness were reported by 38.4% and 37.6% of patients, respectively. OA developed in the medial, lateral, and patellofemoral compartments in 30.7%, 9.3%, and 7.6% of patients, respectively. The onset of OA was associated with partial meniscectomy (odds ratio [OR], 20.73; P = .005) or sagittal tibial tunnel position (OR, 1.18; P = .02) in the medial compartment and body mass index (BMI) (OR, 1.56; P = .02) in the lateral compartment. ACL reconstruction with bone-patellar tendon-bone autograft showed satisfactory clinical results after a mean of 10.3 years. However, pain when walking on hard ground (38.4%) and numbness of the skin (37.6%) were reported. Moreover, the onset of OA appeared in over 40% of the patients. The onset of OA in the medial compartment was correlated with partial meniscectomy and sagittal tibial tunnel position, and the onset of OA in the lateral compartment was correlated with higher BMI. Level IV, therapeutic case series.

Predictors of Radiographic Knee Osteoarthritis After Anterior Cruciate Ligament Reconstruction

Background: Evidence suggests that single-bundle anterior cruciate ligament (ACL) reconstruction does not reliably prevent the development of knee osteoarthritis (OA). Purpose: This study was conducted to determine the overall prevalence of and risk factors for the development of radiographic knee OA after single-bundle ACL reconstruction. Study Design: Case control study; Level of evidence, 3. Methods: There were 249 individuals who had undergone primary single-bundle ACL reconstruction included in this retrospective cohort study. Follow-up radiographs were scored by a single orthopaedic surgery sports medicine fellow using the Kellgren-Lawrence (KL) scale to determine the degree of OA in the medial, lateral, and patellofemoral compartments. Radiographic OA of the involved knee was considered to be present if, compared with the noninvolved knee, there was at least a 2-grade difference in the KL score in at least 1 compartment or a 1-grade difference in at least 2 compartments. Predictors of OA that were explored included patient age, sex, body mass index (BMI), smoking status activity level, meniscectomy before or concurrent with ACL reconstruction, chondral injury present at the time of ACL reconstruction, graft type and source, tibial and femoral tunnel positions, need for revision, and length of follow-up. Univariable and stepwise multivariable logistic regressions were used to identify factors that were associated with radiographic knee OA. Results: Thirty-nine percent of the patients had radiographic OA an average of 7.8 years after surgery. Female sex, BMI, time from injury to surgery, medial and patellofemoral compartment chondrosis, prior medial or lateral meniscectomy, concurrent medial meniscectomy, and length of follow-up were associated with radiographic knee OA after ACL surgery. Stepwise multivariable logistic regression indicated that prior medial meniscectomy (95% confidence interval [CI], 1.39-6.85), grade 2 or greater medial chondrosis (95% CI, 1.27-6.73), length of follow-up (95% CI, 1.07-1.24), and BMI (overweight 95% CI, 1.08-3.84; obese 95% CI, 1.34-7.80) were the best set of predictors of knee OA. Conclusion: Despite reduced laxity and instability and improved activity and participation, individuals who have undergone ACL reconstruction are still at high risk for developing knee OA compared with the general population. The strongest predictors of knee OA after ACL reconstruction were obesity and grade 2 or greater chondrosis in the medial compartment. These results may aid in identifying patients at risk for OA after ACL reconstruction.

Visualization of postoperative anterior cruciate ligament reconstruction bone tunnels

Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed ACL reconstruction. Accurate and reproducible methods to visualize and document bone tunnel placement are therefore important. We evaluated the reliability of standard radiographs, CT scans, and a 3-dimensional (3D) virtual reality (VR) approach in visualizing and measuring ACL reconstruction bone tunnel placement.Methods 50 consecutive patients who underwent single-bundle ACL reconstructions were evaluated postoperatively by standard radiographs, CT scans, and 3D VR images. Tibial and femoral tunnel positions were measured by 2 observers using the traditional methods of Amis, Aglietti, Hoser, Stäubli, and the method of Benereau for the VR approach.Results The tunnel was visualized in 50–82% of the standard radiographs and in 100% of the CT scans and 3D VR images. Using the intraclass correlation coefficient (ICC), the inter- and intraobserver agreement was between 0.39 and 0.83 for the standard femoral and tibial radiographs. CT scans showed an ICC range of 0.49–0.76 for the inter- and intraobserver agreement. The agreement in 3D VR was almost perfect, with an ICC of 0.83 for the femur and 0.95 for the tibia.Interpretation CT scans and 3D VR images are more reliable in assessing postoperative bone tunnel placement following ACL reconstruction than standard radiographs.

Comparison of Anterior Cruciate Ligament Tunnel Position and Graft Obliquity With Transtibial and Anteromedial Portal Femoral Tunnel Reaming Techniques Using High-Resolution Magnetic Resonance Imaging

Using 3-dimensional high-resolution magnetic resonance imaging (MRI), we sought to compare femoral and tibial tunnel position and resultant graft obliquity with single-bundle anterior cruciate ligament (ACL) reconstruction using transtibial (TT) or anteromedial (AM) portal femoral tunnel reaming techniques. Thirty patients were prospectively enrolled after primary, autogenous bone-patellar tendon-bone ACL reconstruction by 2 groups of high-volume, fellowship-trained sports medicine surgeons. With the TT technique, an external starting point was used to maximize graft obliquity and femoral footprint capture. By use of high-resolution MRI and imaging analysis software, bilateral 3-dimensional knee models were created, mirrored, and superimposed. Differences between centroids for each femoral and tibial insertion, as well as corresponding ACL/graft obliquity, were evaluated with paired t tests and 2-sided Mann-Whitney nonparametric tests, with P < .05 defined as significant. No significant differences were observed between groups in position of reconstructed femoral footprints. However, on the tibial side, AM centroids averaged 0.8 ± 1.9 mm anterior to native ACL centroids, whereas the TT group centered 5.23 ± 2.4 mm posterior to native ACL centroids (P < .001). Sagittal obliquity was closely restored with the AM technique (mean, 52.2° v. 53.5° for native ACL) but was significantly more vertical (mean, 66.9°) (P = .0001) for the TT group. In this clinical series, AM portal femoral tunnel reaming more accurately restored native ACL anatomy than the TT technique. Although both techniques can capture the native femoral footprint with similar accuracy, the TT technique requires significantly greater posterior placement of the tibial tunnel, resulting in decreased sagittal graft obliquity. When a tibial tunnel is drilled without the need to accommodate subsequent femoral tunnel reaming, more accurate tibial tunnel position and resultant sagittal graft obliquity are achieved. Level III, retrospective comparative study.

PCL to graft impingement pressure after anatomical or non-anatomical single-bundle ACL reconstruction

Anterior cruciate ligament (ACL) graft impingement against the posterior cruciate ligament (PCL) has been postulated, but not thoroughly investigated. To evaluate PCL impingement pressure and biomechanical stability with different tibial and femoral tunnel positions in ACL reconstruction. In 15 porcine knees, the impingement pressure between ACL and PCL was measured using pressure sensitive film before and after ACL single-bundle reconstruction. ACL reconstructions were performed in each knee with three different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM-AM), (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL-High-AM) and (3) tibial AM tunnel to femoral High-AM tunnel (AM-High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. There was no significant difference of the impingement pressure between AM and AM, PL-High-AM reconstructed groups and intact ACL. Only AM-High-AM ACL reconstruction group showed significantly higher impingement pressure compared with intact ACL. With regard to ATT, AM-AM group had significantly higher stiffness than PL-High-AM group. Anatomical ACL reconstruction does not cause PCL impingement and it has biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in porcine knee. For the clinical relevance, in the anatomical ACL reconstruction, no ACL-PCL impingement is found.

The Transverse Ligament as a Landmark for Tibial Sagittal Insertions of the Anterior Cruciate Ligament: A Cadaveric Study

The purpose of this study was to determine the relation between the position of the transverse ligament, the anterior edge of the anterior cruciate ligament (ACL) tibial footprint, and the center of the ACL tibial insertion. We used arthroscopy for localization of the anatomic landmarks, followed by insertions of guide pins under direct visualization, and then the position of these guide pins was checked on plain lateral radiographs. The transverse ligament and the anterior aspect of the ACL tibial footprint were identified by arthroscopy in 20 unpaired cadaveric knees (10 left and 10 right). Guide pins were inserted with tibial ACL adapter drill guides under direct observation at the transverse ligament, the anterior aspect of the tibial footprint, and the center of tibial insertion of the ACL. Then, plain lateral radiographs of specimens were taken. The Amis and Jakob line was used to define the attachment of the ACL tibial insertion and the transverse ligament. A sagittal percentage of the location of the insertion point was determined and calculated from the anterior margin of the tibia in the anteroposterior direction. The transverse ligament averaged 21.20% ± 4.1%, the anterior edge of the ACL tibial insertion averaged 21.60% ± 4.0%, and the center of the ACL tibial insertion averaged 40.30% ± 4.8%. There were similar percent variations between the transverse ligament and the anterior edge of the ACL tibial insertion, with no significant difference between them (P = .38). Intraobserver and interobserver reliability was high, with small standard errors of measurement. This study shows that the transverse ligament coincides with the anterior edge of the ACL tibial footprint in the sagittal plane. The transverse ligament can be considered as a new landmark for tibial tunnel positioning during anatomic ACL reconstruction.

Tunnel position and graft orientation in failed anterior cruciate ligament reconstruction: a clinical and imaging analysis

It has been reported that technical error in positioning the graft tunnel is the most common problem in anterior cruciate ligament (ACL) reconstruction. The objective of this study was to quantitatively evaluate femoral and tibial tunnel positions and intra-articular graft orientation of primary ACL reconstruction in patients who had undergone revision ACL reconstruction. We postulated that this patient cohort had a nonanatomically positioned tunnel and graft orientation. Twenty-six patients who had undergone a revision ACL were investigated. Clinical magnetic resonance (MR) images prior to revision were analysed. Three-dimensional models of bones and tunnels on the femur and tibia were created. Intra-articular graft orientation was measured in axial, sagittal and coronal planes. Graft positions were measured on the tibial plateau as a percentage from anterior to posterior and medial to lateral; graft positions on the femur were measured using the quadrant method. Sagittal elevation angle for failed ACL reconstruction graft (69.6° ± 13.4°) was significantly greater (p < 0.05) than that of the native anteromedial (AM) and posterolateral (PL) bundles of the ACL (AM 56.2° ± 6.1°, PL 55.5° ± 8.1°). In the transverse plane, the deviation angle of the failed graft (37.3° ± 21.0°) was significantly greater than native ACL bundles. The tibial tunnel in this patient cohort was placed posteromedially and medially to the anatomical AM and PL bundles, respectively. The femoral tunnel was placed anteriorly to the anatomical AM and PL bundles. This study reveals that both the tibial and femoral tunnel positions and consequently the intra-articular graft orientation in this patient group with failed ACL reconstruction were nonanatomical when compared with native ACL values. The results can be used to improve tunnel placement in ACL reconstruction.

MR in the evaluation of new anterior cruciate ligament and tibial tunnel position: correlation with clinical and functional features

This study aimed to evaluate correlations between the position of the tibial tunnel, its alignment with the ligament-screw system, presence of intratunnel fluid, position of the tibial tunnel with respect to the Blumensaat line and clinical knee stability in patients who underwent arthroscopic reconstruction of the anterior cruciate ligament (ACL), by using magnetic resonance (MR) imaging. Forty-eight patients (40 men, eight women; mean age, 31 years) underwent arthroscopic reconstruction of the ACL using double-strand semitendinosus and gracilis tendons. The new ACL was fixed to the tibial tunnel using Bio-Intrafix (Mitek). All patients underwent MR imaging 12 months after surgery and clinical evaluation at 6 and 12 months using the International Knee Documentation Committee (IKDC) scoring system. MR imaging and clinical features were correlated using the Mann-Whitney U test for continuous variables and Fisher's exact test for categorical variables. Forty-one patients were clinically stable (groups A and B according to the IKDC test) and seven were unstable (group C). Mean values of tibial tunnel position in clinically unstable vs stable patients were, respectively, -3.6 ±3.8 mm vs. -2.8±3.8 mm in relation to the Blumensaat line (p=0.5712) and 77.3°±11.3 vs. 72.5°±5.5 as concerned the angle measured on the coronal view of the new ACL (p=0.3248); fluid was present in the tibial tunnel in 42.9% and 9.8% of cases, respectively (p=0.2104). MR imaging showed misalignment of ligament screw and tibial tunnel in 57.1% of patients in group C and in 12.2% in groups A and B (p=0.017). Misalignment of the ligament-screw system and the tibial tunnel and the presence of fluid in the tibial tunnel appear to be directly correlated with clinical instability.

Effect of Femoral Socket Position on Graft Impingement After Anterior Cruciate Ligament Reconstruction

Background: Despite improved biomechanical stability and kinematics with anatomic anterior cruciate ligament (ACL) reconstruction, concerns regarding notch impingement of the graft have persisted, particularly with increasingly anterior tibial tunnel position. The potentially mitigating effect of anatomic femoral socket position, however, has not been evaluated. Hypothesis: Placement of the femoral socket in the central or posterolateral bundle footprint reduces the risk and magnitude of graft impingement after ACL reconstruction compared with placement in the anteromedial bundle footprint. Study Design: Controlled laboratory study. Methods: This study employed computer-assisted navigation in a cadaveric model to evaluate the effect of tibial and femoral tunnel position on ACL graft impingement. Sixteen cadaveric knees were tested using the Praxim ACL Surgetics Navigation System, with the tibial tunnel positioned in the footprint of the anteromedial bundle and the femoral socket placed in the (1) anteromedial bundle footprint, (2) center of footprint, or (3) posterolateral bundle footprint. The amount of maximum impingement, angle of initial impingement, and location of graft impingement were documented through a full arc of knee motion. Results: Impingement occurred with all 3 femoral socket positions, but the mean angle of impingement with the anteromedial femoral position (42.8° ± 26.4°) was significantly greater (P < .003) than the mean angles of impingement with the central femoral position (19.4° ± 19.2°) and the posterolateral bundle femoral position (16.7° ± 13.3°). Conclusion: Although notch impingement was seen in all femoral socket locations with an anteromedial tibial socket position, femoral socket position in a central or posterolateral bundle location may reduce the risk and magnitude of graft impingement after ACL reconstruction. Additional studies are necessary to determine the influence of these different constructs on graft isometry and knee kinematics. Clinical Relevance: Anatomic femoral socket position in the center of the native ACL footprint may reduce the risk and magnitude of notch impingement compared with an anteromedial bundle position with ACL reconstruction.

Knee Laxity Control in Revision Anterior Cruciate Ligament Reconstruction Versus Anterior Cruciate Ligament Reconstruction and Lateral Tenodesis

Background: Rotational laxity control is one of the different options to improve functional results after anterior cruciate ligament reconstruction. Lateral extra-articular tenodesis has been proposed to reduce the rotational laxity, especially in challenging situations such as revision reconstruction after biological failure. We currently lack the practical clinical tools to objectively assess knee rotational laxities. Hypothesis: Addition of a lateral tenodesis to anatomic single-bundle anterior cruciate ligament reconstruction with hamstring tendon graft could improve the knee laxity control, particularly the internal rotation, compared with a standard single-bundle anterior cruciate ligament reconstruction. Study Design: Controlled laboratory study. Methods: Twenty patients underwent navigated anatomic anteromedial bundle revision anterior cruciate ligament reconstruction with addition of percutaneous extra-articular tenodesis using the same hamstring tendon graft. The navigation was used to optimize femoral and tibial tunnel positions and to measure the knee kinematics in response to the anterior drawer test, Lachman test, maximum internal/external rotation test, and pivot-shift test. All patients underwent revision after failure without any technical error found or new trauma. Two sequential reconstruction protocols were used to assess the contribution of the extra-articular tenodesis and single anteromedial bundle anterior cruciate ligament reconstruction to restrain tibial translations and coupled axial rotation occurring with the manually performed clinical laxity tests. In group A, the intra-articular reconstruction was fixed first and then the lateral tenodesis was fixed, and in group B, the protocol was reversed. Measurements were performed before the reconstruction, after the first part was fixed, and after the second part was fixed in each protocol. Results: At 90° of flexion, addition of lateral tenodesis had a significant effect on coupled internal rotation (P = .003). Addition of the intra-articular reconstruction to lateral tenodesis had a significant effect (P = .001) in reducing anterior tibial translation of the medial compartment, and the effect was also significant (P = .0001) in reduction of lateral compartment translation. For the rotational envelope, lateral tenodesis had a significant effect (P = .0001) in reducing maximum internal rotation at 90° of flexion. Conclusion: Addition of an extra-articular procedure provided no significant improvement to anterior tibial translation and improved internal tibial rotation control only at 90° of flexion.

Reliability of tunnel angle in ACL reconstruction: two-dimensional versus three-dimensional guide technique

To compare the reliability of tibial tunnel position and angle produced with a standard ACL guide (two-dimensional guide) or Howell 65° Guide (three-dimensional guide) in the coronal and sagittal planes. In the sagittal plane, the dependent variables were the angle of the tibial tunnel relative to the tibial plateau and the position of the tibial tunnel with respect to the most posterior aspect of the tibia. In the coronal plane, the dependent variables were the angle of the tunnel with respect to the medial joint line of the tibia and the medial and lateral placement of the tibial tunnel relative to the most medial aspect of the tibia. The position and angle of the tibial tunnel in the coronal and sagittal planes were determined from anteroposterior and lateral radiographs, respectively, taken 2-6 months postoperatively. The two-dimensional and three-dimensional guide groups included 28 and 24 sets of radiographs, respectively. Tibial tunnel position was identified, and tunnel angle measurements were completed. Multiple investigators measured the position and angle of the tunnel 3 times, at least 7 days apart. The angle of the tibial tunnel in the coronal plane using a two-dimensional guide (61.3 ± 4.8°) was more horizontal (P < 0.05) than tunnels drilled with a three-dimensional guide (64.7 ± 6.2°). The position of the tibial tunnel in the sagittal plane was more anterior (P < 0.05) in the two-dimensional (41.6 ± 2.5%) guide group compared to the three-dimensional guide group (43.3 ± 2.9%). The Howell Tibial Guide allows for reliable placement of the tibial tunnel in the coronal plane at an angle of 65°. Tibial tunnels were within the anatomical footprint of the ACL with either technique. Future studies should investigate the effects of tibial tunnel angle on knee function and patient quality of life. Case-control retrospective comparative study, Level III.