Anterior Cruciate Ligament Tibial Attachment Research Articles

Femoral intercondylar notch: Accuracy of a novel MRI measurement protocol

ObjectiveThe most common mechanical complication following an anterior cruciate ligament (ACL) reconstruction is joint stiffness, due in part to cyclops syndrome. A narrow intercondylar notch is an anatomical risk factor. A reliable preoperative notch measurement would help anticipate proper graft size, or plan a notchplasty during the ligament reconstruction, if necessary. No study has yet assessed the accuracy of the methods used to measure notch size. HypothesisThe novel measurement protocol proposed in this study would be more reproducible than the reference technique. MethodsA total of 20 preoperative knee MRIs performed during the assessment of an ACL rupture were randomly selected. The notch size was measured using 2 methods: traditional (ratio of the notch and metaphyseal widths measured on a line drawn through the popliteal groove) and novel. The latter was measured using the same ratio but took into account the notch width in its proximal third, according to a coronal slice that passes through the ACL tibial attachment. Three orthopedic surgeons with different levels of experience (senior surgeon, junior surgeon and surgical resident) performed these measurement protocols twice on anonymized MRI scans, 10days apart. Spearman's rank correlation coefficient was used to assess the intraobserver correlations and a concordance index was used to assess the interobserver correlations. The influence of the second MRI reading was analyzed with a bootstrap test. ResultsThe mean intraobserver reliability was 0.73 for the reference method and 0.83 for the proposed method. The values of the bootstrap tests were higher for the proposed method (0.45 vs. 0.45 and 0.70; p<05 for interobserver; 0.49 vs. 0.69 and 0.62; p<05 for intraobserver). ConclusionThe proposed measurement protocol showed a higher reproducibility in assessing notch size than the traditional method. This technique therefore provides a reliable assessment of the intercondylar notch width. Level of evidenceIV; retrospective study.

A novel arthroscopically assisted reduction technique for three patterns of posterolateral tibial plateau fractures

BackgroundPosterolateral tibial plateau fractures (PTPF) remain a challenge for orthopedics surgeons because the special anatomical structures of the posterolateral corner of knee joint including the fibular head, the lateral collateral ligament, and the peroneal nerve, which impedes the exposure of the fracture fragments and need irregular implants to get a stable fixation. The purpose of present study was to introduce a new articular fracture fragments restoration technique for three patterns of PTPF and investigate the relationship between associated soft injuries and fracture patterns.MethodsFrom May 2016 to April 2018, 31 patients with PTPF who had undertaken arthroscopically assisted reduction and fixation (AARF) were enrolled in present study. Demographic data, pre-operation, and post-operation X plan films, three-dimensional computed tomography (CT) scans and magnetic resonance imaging (MRI) were reviewed. Present samples were divided into three patterns with lateral inclination (LI), posterior inclination (PI), and parallel compression (PC) according to the orientation of the articular fragment inclination. Rasmussen anatomical score was used to assess the radiological results. Rasmussen functional score, Hospital for Special Surgery knee-rating Score (HSS), and range of motion (ROM) of the knee joint at the final follow-up were measured to evaluate the clinical outcomes.ResultsIn this series, the post-operation tibial plateau angle (TPA) was 9.7° ± 3.5°(range 4.0°–15.8°) and the Rasmussen anatomical score was 17.7 ± 0.7(range 16–18); clinical outcomes showed that the HSS score was 92.7 ± 21.8 (range 90–96) and the Rasmussen functional score was 27.9 ± 1.0 (range 26–30). Of all the patients, the anterior cruciate ligament (ACL) injuries including the ACL tibial attachment ruptures occurred in 16 patients (51.6%), meniscus lesions happened in 19 patients (61.3%), medial collateral ligament (MCL) injuries were founded in 13 patients (41.9%). The number of ACL injuries including the ACL tibial attachment ruptures in the PI fracture pattern (12 cases) is significantly higher than LI (2 cases) and PC (2 cases) fracture pattern (p < 0.05).ConclusionProfound understanding the different patterns of PTPF and using our reduction technique will facilitate to restore the main articular fracture fragments. The PI fracture patterns have a significant high incidence of the ACL ruptures.Level of evidenceTherapeutic study, Level IV.

ACL Growth With Age in Pediatric Patients: An MRI Study.

There is limited knowledge of morphologic changes of the anterior cruciate ligament (ACL) during childhood. The purpose of the study is to describe normal ACL growth in pediatric patients. We performed retrospective review of patients under 19 years of age with at least 2 serial magnetic resonance imaging (MRI) examinations of the same knee without ACL tear. The parameters measured included length of the ACL, width of the ACL in sagittal and coronal planes, physeal status, ACL-tibial inclination angle, Notch Width Index, ACL tibial attachment width and midpoint, and anterior to posterior length and height of the tibial epiphysis. Pearson correlation coefficients were calculated to determine the strength of correlation of each parameter relative to age. Growth curves were calculated for individual parameters, producing a predictive model for growth of the ACL over time. One hundred forty-seven patients (365 MRIs) were included. The average age at initial MRI was 12.2 years (range: 1.2 to 18.4 y). The Pearson correlation coefficient for each parameter was statistically significant relative to age. Younger patients had more oblique, anteriorly attached ACLs. Three distinct phases of growth were observed: patients age 1.5 to 5.75 years average 2.25 mm of growth per year; patients aged 6 to 11.5 average 1.46 mm of growth per year; growth slows at age 11.75, stopping by 18.5 years. The growth model for ACL sagittal width increased 0.45 mm/y from age 1.5 to 14.5 after which it plateaus, whereas coronal width increased 0.22 mm/y from age 1.5 to 18.75. In the pediatric patient, the ACL grows in length and width in a predictable manner until age 18. This model aids clinicians in predicting normal ACL parameters for anatomic reconstruction procedures in the skeletally immature patient. Level IV.

The Role of Fibers Within the Tibial Attachment of the Anterior Cruciate Ligament in Restraining Tibial Displacement

To evaluate the load-bearing functions of the fibers of the anterior cruciate ligament (ACL) tibial attachment in restraining tibial anterior translation, internal rotation, and combined anterior and internal rotation laxities in a simulated pivot-shift test. Twelve knees were tested using a robot. Laxities tested were: anterior tibial translation (ATT), internal rotation (IR), and coupled translations and rotations during a simulated pivot-shift. The kinematics of the intact knee was replayed after sequentially transecting 9 segments of the ACL attachment and fibers entering the lateral gutter, measuring their contributions to restraining laxity. The center of effort (COE) of the ACL force transmitted to the tibia was calculated. A blinded anatomic analysis identified the densest fiber area in the attachment of the ACL and thus its centroid (center of area). This centroid was compared with the biomechanical COE. The anteromedial tibial fibers were the primary restraint of ATT (84% across 0° to 90° flexion) and IR (61%) during isolated and coupled displacements, except for the pivot-shift and ATT in extension. The lateral gutter resisted 28% of IR at 90° flexion. The anteromedial fibers showed significantly greater restraint of simulated pivot-shift rotations than the central and posterior fibers (P < .05). No significant differences (all <2mm) were found between the anatomic centroid of the C-shaped attachment and the COE under most loadings. The peripheral anteromedial fibers were the most important area of the ACL tibial attachment in the restraint of tibial anterior translation and internal rotation during isolated and coupled displacements. These mechanical results matched the C-shaped anteromedial attachment of the dense collagen fibers of the ACL. The most important fibers in restraining tibial displacements attach to the C-shaped anteromedial area of the native ACL tibial attachment. This finding provides an objective rationale for ACL graft position to enable it to reproduce the physiological path of load transmission for tibial restraint.

Relationship between anterior cruciate ligament and anterolateral meniscal root bony attachment: High-resolution 3-T MRI analysis

BackgroundThe tibial bony attachments of the anterior cruciate ligament (ACL) and the anterolateral meniscal root (ALMR) are very close, and drilling the tibial tunnel in ACL reconstruction may damage the ALMR attachment. This study investigated the relationship between the tibial attachment of the ACL and ALMR using high-resolution 3-T magnetic resonance imaging (MRI). MethodsTwenty healthy subjects (35.8 ± 13.0 years) had 20 knees scanned using high resolution 3-T MRI. The tibial bony attachments of ACL, ALMR, and the tibia were segmented and three-dimensional models were created. The shape, area, and location of each attachment were evaluated using this model. ResultsThe ACL tibial attachment was elliptical in nine knees (45%), C-shaped in nine knees (45%) and triangle in two knees (10%). The mean values of the ACL vs ALMR tibial attachments were as follows: area, 106.2 ± 21.3 vs 56.2 ± 21.3 mm2; length, 16.8 ± 2.0 vs 11.0 ± 1.8 mm; and width, 6.9 ± 1.3 vs 6.6 ± 1.0 mm. The location of the ACL vs ALMR attachment centres was 46.5 ± 1.7% vs 56.5 ± 1.9% in the medial-lateral direction and 36.3 ± 3.6% vs 36.7 ± 3.5% in the anterior–posterior direction. The distance between the ACL and ALMR centres was 8.1 ± 1.3 mm. ConclusionsACL and ALMR tibial attachments were individually distinguished using high resolution 3-T MRI. The short distance between both centres of the attachments may suggest that ALMR can be damaged when the tibial tunnel is drilled in ACL reconstruction.

ACL GROWTH WITH AGE IN PEDIATRIC PATIENTS: AN MRI STUDY

BackgroundThe incidence of anterior cruciate ligament (ACL) injury is steadily increasing in skeletally immature patients [1-7]. As a result, surgical approaches to reconstruction of the ACL withou...

Stereophotogrammetric surface anatomy of the anterior cruciate ligament's tibial footprint: Precise osseous structure and distances to arthroscopically-relevant landmarks

BackgroundWhile femoral tunnel malposition is widely recognized as the main technical error of failed anterior cruciate ligament (ACL) surgery, tibial tunnel malposition is likely underrecognized and underappreciated. PurposeTo describe more precisely the qualitative and quantitative anatomy of the ACL's tibial attachment in vitro using widely available technology for stereophotogrammetric surface reconstruction, and to test its applicability in vivo. MethodsStereophotogrammetric surface reconstruction was obtained from fourteen proximal tibias of cadaver donors. Measurements of areas and distances from the center of the ACL footprint and the footprint of the obtained bundles to selected arthroscopically-relevant anatomic landmarks were carried out using a three-dimensional design software program, and means and 95% confidence intervals were calculated for these measurements. Reference landmarks were tested in three-dimensional models obtained with arthroscopic videos. Main findingsThe osseous footprint of the ACL was described in detail, including its precise elevated limits, size, and shape, with its elevation pattern described as a quarter-turn-staircase-like ridge. Its internal indentations were related to inter-spaces identified as bundle divisions. Distances from the footprint center to arthroscopically relevant landmarks were obtained and compared to its internal structure, yielding a useful X-like landmark pointing to the most accurate placeholder for the ACL footprint's “anatomic” center. Certain structures and reference landmarks described were readily recognized in three-dimensional models from arthroscopic videos. ConclusionsStereophotogrammetric surface reconstruction is an accessible technique for the investigation of anatomic structures in vitro, offering a detailed three-dimensional depiction of the ACL's osseous footprint.

A study on associated injuries of anterior cruciate ligament tear

Introduction: Over the last decade, reconstruction of the anterior cruciate ligament (ACL) has evolved from a surgical technique in which the objectives were ‘isometric’ femoral tunnel placement and avoidance of inter-condylar notch roof impingement, towards an ‘anatomic’ surgical technique which attempts to restore the native ACL. Achieving the goals of isometric ACL graft placement and avoidance of roof impingement often resulted in the ACL femoral tunnel extending into the roof of the notch, outside of the native ACL femoral attachment site and the tibial tunnel being positioned in the posterior half of the native ACL tibial attachment site. Methodology: All patients admitted with clinico-radiological diagnosis of ACL tear with h/o injury (trauma) who met the inclusion criteria. This was a Prospective observational study with the minimum follow up 12 months. The sample size was 30. Results: A Total of 90% (27 cases) (n=27) patients had associated injuries usually the meniscal tear. Isolated medial meniscal tear were found in 33.3% (10 cases) (n=10) while isolated lateral meniscus tear were found in 33.3% (10 patients) (n=10) of cases. Combined medial and lateral meniscus tear were found in 23%% (7 cases) (n=7). Conclusion: Chondral changes were found in 30% (9 cases) (n=9) MCL, LCL and posterior cruciate ligament tear was found in none.

Arthroscopic treatment of avulsion fracture of tibial attachment of anterior cruciate ligament using double Endobutton plates

Objective To explore the feasibility and curative effect of arthroscopic treatment of avulsion fracture of the tibial attachment of anterior cruciate ligament (ACL) using Ethibood line plus double Endobutton plates. Methods From May 2014 to January 2016, 26 cases of acute ACL tibial attachment fracture were treated surgically. They were 16 males and 10 females, aged from 9 to 45 years (average, 26.6 years). By the Meyers-McKeeve classification, there were 17 cases of type Ⅱ and 9 ones of type Ⅲ. In preoperative examina-tion, their Lachman test and Anterior Drawer Test were all positive. All their bone blocks were fixated using Ethibond line plus double Endobutton plates. Results Their operative time ranged from 50 to 70 min, averaging 57 min. On average, the 26 patients obtained a follow-up of 8 months (from 6 to 13 months). X-rays at 3 months after operation showed all fractures united. At the last follow-up, their Lachman test and Anterior Drawer Test were all negative. The range of motion of the knee joint was larger than 120° in all; their Lysholm score of the knee joint averaged 90.6±2.9 points, significantly higher than their preoperative value (43.6±4.7 points) (t=7.583, P=0.026); their International Knee Documentation Committee (IKDC) scores averaged 93.1±4.2 points, significantly higher than their preoperative value (46.3±5.1 points) (t=8.162, P=0.021). No such complications as reflexive neural dystrophy, avascular necrosis or weak knee extension occurred during follow-ups. Conclusion The avulsion fractures of ACL tibial attachment can be treated arthroscop-ically using Ethibood line plus double Endobutton plates, because this technique has such advantages as simple operation, limited invasion, good fracture reduction, strong fixation, and possibility of early functional rehabil-itation of the knee joint. Key words: Arthroscopy; Anterior cruciate ligament; Tibial fractures; Fracture fixation, inter-nal; Bone plates

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

Background:Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement.Purpose:To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling.Study Design:Controlled laboratory study.Methods:Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement.Results:Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof.Conclusion:The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement.Clinical Relevance:Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Femoral and Tibial Graft Tunnel Parameters After Transtibial, Anteromedial Portal, and Outside-In Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation. Purpose/Hypothesis: The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site. Study Design: Cohort study; Level of evidence, 3. Methods: The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites. Results: There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques. Conclusion: The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

MRI Anatomy of the Tibial ACL Attachment and Proximal Epiphysis in a Large Population of Skeletally Immature Knees

Background: To aid in performing anatomic physeal-sparing anterior cruciate ligament (ACL) reconstruction, it is important for surgeons to have reference data for the native ACL attachment positions and epiphyseal anatomy in skeletally immature knees. Purpose: To characterize anatomic parameters of the ACL tibial insertion and proximal tibial epiphysis at magnetic resonance imaging (MRI) in a large population of skeletally immature knees. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The ACL tibial attachment site and proximal epiphysis were examined in 570 skeletally immature knees with an intact ACL (age, 6-15 years) using 1.5-T proton density–weighted sagittal MRI; also measured were the tibial anteroposterior diameter; anterior, central, and posterior ACL attachment positions; vertical height of the epiphysis; and maximum oblique epiphyseal depth extending from the ACL tibial attachment center to the tibial tuberosity. Results: In adolescents (11-15 years of age), the center of the ACL’s tibial attachment was 51.5% ± 5.7% of the anteroposterior diameter of the tibia, with no significant differences between sexes or age groups (P > .05 in all cases). Mean vertical epiphyseal height was 15.9 ± 1.7 mm in the adolescent group, with significant differences between 11-year-olds (15.2 ± 1.5 mm) and 15-year-olds (16.6 ± 1.6 mm), P < .001, and between males (16.6 ± 1.5 mm) and females (14.8 ± 1.4), P < .001. Mean maximum oblique depth was 30.0 ± 5.3 mm, with a significant difference between 11-year-olds (26.7 ± 4.9 mm) and 15-year-olds (32.7 ± 5.1 mm), P < .001, and between males (29.7 ± 6.4 mm) and females (27.8 ± 5.2 mm), P < .001. The maximum oblique depth occurred at a mean angle of ~50°, and this angle did not change with age or sex. There was a significant moderate correlation (r = 0.39, P < .001) between epiphyseal vertical height and maximum oblique depth. Conclusion: The center of the ACL tibial attachment was consistently near 51% of the anteroposterior diameter, regardless of age or sex. The vertical depth of the tibial epiphysis was ~16 mm in adolescents. Maximum oblique depth from ACL attachment was ~30 mm, occurring at a mean angle ~50° regardless of age or sex. The normative values for tibial ACL attachment and epiphyseal anatomy presented here may be helpful in selecting candidates for surgery and in planning surgical approaches for pediatric ACL reconstruction.

Reliability of Estimates of ACL Attachment Locations in 3-Dimensional Knee Reconstruction Based on Routine Clinical MRI in Pediatric Patients

Background: Current techniques of anterior cruciate ligament (ACL) reconstruction focus on the placement of femoral and tibial tunnels at anatomic ACL attachments, which can be difficult to identify intraoperatively. Purpose: To determine whether the 3-dimensional (3D) center of ACL attachments can be reliably detected from routine magnetic resonance imaging (MRI) in patients with intact ACLs and whether the reliability of this technique changes if the ACL is torn. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A computer technique was developed in which users identify points along ACL attachments on routine clinical MRI of preoperative knees. These attachments are then displayed on a 3D MRI reconstruction, which can be used as a visual guide for the surgeon during arthroscopic surgery. Thirty-seven pediatric patients (age range, 10-17 years) with ACL tears and 37 controls with intact ACLs were examined. Two blinded observers identified cruciate ligament attachments on routine clinical 1.5-T MRI of knees. From the resulting 3D model, the location of the center of each ligament attachment site and its area were calculated and reliability assessed. Results: Mean interobserver variation of the centers of ACL attachments for the intact versus torn ACL was 1.7 ± 0.9 mm versus 1.8 ± 1.1 mm (femoral) and 1.4 ± 0.9 mm versus 1.7 ± 1.0 mm (tibial), respectively (P > .05). The 95% confidence interval for the center location was at most 4 mm. The identified ACL attachment areas were more variable, with interobserver reliability ranging from fair to excellent by the intraclass correlation coefficient. Overlap of ligament areas between observers for the intact versus torn ACL was 70% ± 15% versus 73% ± 12% (femoral) and 79% ± 9% versus 78% ± 10% (tibial), respectively (P > .05). In all cases, intraobserver reliability was superior to interobserver reliability. Conclusion: The 3D locations of ACL tibial and femoral attachment centers were identified from routine clinical MRI with variability averaging less than 2 mm between 2 observers. The margin of error was at most 4 mm, representing the thickness of a single axial MRI slice, whether the ACL was intact or torn. Remnant tissue at attachments allows a reliable assessment even of torn ligaments. Identification of the ligament attachment areas was more user dependent than was identification of the attachment centers.

Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction

The aim of the paper is to describe the medial portal technique for anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Placement of an ACL graft within the anatomical femoral and tibial attachment sites is critical to the success and clinical outcome of ACL reconstruction. Non-anatomical ACL graft placement is the most common technical error leading to recurrent instability following ACL reconstruction. ACL reconstruction has commonly been performed using a transtibial tunnel technique in which the ACL femoral tunnel is drilled through a tibial tunnel positioned in the posterior half of the native ACL tibial attachment site. ACL reconstruction performed using a transtibial tunnel technique often results in a vertical ACL graft, which may fail to control the combined motions of anterior tibial translation and internal tibial rotation which occur during the pivot-shift phenomenon. The inability of a vertically oriented ACL graft to control these combined motions may result in the patient experiencing continued symptoms of instability due to the pivot-shift phenomenon. The medial portal technique in which the ACL femoral tunnel is drilled through an anteromedial or accessory anteromedial portal allows consistent anatomical ACL tunnel placement. This paper describes the advantages of the medial portal technique, indications for the technique, patient positioning, proper portal placement, anatomical femoral and tibial tunnel placement, graft tensioning and fixation.

Anatomic attachment of the ACL. Comparison between radiological and CT analysis

The following hypothesis was tested: the location of the tibial and femoral anterior cruciate ligament (ACL) attachments will differ according to the measurement technique (plain radiographs or CT-scan) in relation to the anatomic frame of reference. 10 gross specimens were studied. The location of metallic reference pins implanted around the tibial and femoral ACL attachments was recorded with reference to the bone contours with a caliper on the anatomic preparation, with standard plain AP and lateral radiographs and with a CT-scan. Results were compared with appropriate statistical tests at a 0.05 level of significance. The mean ratio between the antero-posterior tibia measurement and the center of the ACL tibial attachment varied from 50 to 52%. The mean ratio between the medio-lateral tibia measurement and the center of the ACL tibial attachment varied from 49 to 51%. The mean ratio between the antero-posterior femur measurement and the center of the ACL femoral attachment varied from 74 to 80%. The results were significantly different between the three techniques (respectively P=0.003, P=0.02 and P=0.045). The paired differences were small (3% at the tibia, 6% at the femur). There was a strong correlation and a good agreement between the three techniques. It is likely that the small differences on the tibia have few, if any, clinical relevance. Both radiographic and CT-scan measurement techniques used during the present study have the potential to be used as quality control after ACL replacement. Diagnostic study-investigating a diagnostic test. Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Prevalence of Nonanatomical Graft Placement in a Series of Failed Anterior Cruciate Ligament Reconstructions

Background Anterior cruciate ligament reconstruction employing transtibial tunnel techniques may result in less than ideal femoral and tibial vertical graft placement, with a residual pivot shift and instability symptoms. Hypothesis Nonanatomical graft placement is highly prevalent among knees with failed primary and revision anterior cruciate ligament grafts. Study Design Case series; Level of evidence, 4. Methods A total of 122 consecutive patients presented to the authors’ center with a failed anterior cruciate ligament reconstruction. Radiographs, magnetic resonance imaging, and operative reports were used to define graft placement. Arthroscopic confirmation of graft placement was obtained in 92 knees during subsequent revision surgery. A nonanatomical graft placement was assigned when ≥50% of the graft was outside of the native tibial and femoral insertions. All patients prospectively completed Cincinnati Knee Rating System questionnaires. Results A nonanatomical graft placement occurred in 107 of 122 (88%) knees; 61% of the grafts were entirely on the intercondylar femoral roof, and 35% extended posterior to the anterior cruciate ligament tibial attachment. A transtibial technique had been used in 83%. The mean values for the coronal and sagittal graft placement showed a significantly increased vertical orientation in comparison with a control group (P < .01). Forty-two of the 107 nonanatomical grafts had undergone 1 or more revisions without correction of the misplaced graft tunnels, and these subsequently failed. Conclusion The occurrence of nonanatomical graft placement in primary and revision knees may represent an inadequacy of transtibial tunnel drilling techniques to obtain graft placement within the native femoral and tibial footprints. In revision cases, the prior graft location requires close scrutiny so the new graft tunnels are placed at the native anterior cruciate ligament attachments. Independent drilling of tibial and femoral tunnels is recommended using either 2-incision or anteromedial portal techniques.

Anatomy of Normal Human Anterior Cruciate Ligament Attachments Evaluated by Divided Small Bundles

Background Double-bundle anterior cruciate ligament (ACL) reconstruction has several potential advantages over single-bundle reconstruction with hamstring tendons. However, there are still controversies regarding tunnel placement in tibial and femoral attachments. Hypothesis The macroscopically normal ACL consists of small bundles about 1 mm in diameter. Detailed observation of the divided smaller bundles will achieve better understanding of the tunnel placement in anatomic ACL reconstruction. Study Design Descriptive laboratory study. Methods This study used 20 cadaveric knees. The ACL was divided into anteromedial and posterolateral bundles, then separated into 10 small bundles of 2-mm diameters, with preservation of their attachment sites marked with color markers. The positional relationship between the femoral and tibial attachments of each small bundle was investigated. Results A layered positional correlation of small bundles was found between the tibial and femoral attachments. Small bundles aligned in the anterior-posterior direction in the tibia corresponded to the bundles aligned in a high-low direction in the femur in flexion. The femoral attachment pattern was relatively similar in each specimen; however, the tibial attachment showed 2 patterns: an oblique type (12 of 20) and a transverse type (8 of 20). The posterior portion of the posterolateral bundle was separately attached to the medial and lateral portions of the tibial attachment. There was no fibrous insertion in the center of the posterior portion of the ACL tibial attachment in any specimen. In this bare area, there was fat tissue and vascular bundles. Conclusion Small bundles constituting the ACL showed a relatively layered arrangement between 2 attachments. The tibial attachment showed 2 patterns of oblique and transverse types, and the vascular bundles were located in the center of the posterolateral bundle. Clinical Relevance The results of this study of the normal ACL will provide insights for surgeons when placing grafts during anatomic ACL reconstruction.