Do Rotation and Measurement Methods Affect Reliability of Anterior Cruciate Ligament Tunnel Position on 3D Reconstructed Computed Tomography?

Proximally positioned femoral grafts decrease passive anterior tibial subluxation in anterior cruciate ligament reconstruction using a posterior trans-septal portal

PURPOSE

To compare the anterior and posterior trans-septal (TS) portal approaches in anterior cruciate ligament reconstruction (ACLR) by evaluating femoral tunnel positioning and passive anterior tibial subluxation (PATS).

METHODS

A total of 205 patients who underwent primary ACLR using the outside-in technique between March 2018 and December 2021 were retrospectively enrolled. Patients were classified into two groups based on the viewing techniques: the anterior group was treated using anteromedial or anterolateral portals (n = 155), and the TS group was treated using posterior TS portal (n = 55). The relative locations of the femoral tunnel were evaluated using the deep-shallow planes (X-axis) and superior-inferior planes (Y-axis) with the quadrant method in the lateral femoral condyle on a 3-dimensional computed tomography image. Anterior tibial subluxation for the lateral and medial compartments relative to the femoral condyles was evaluated as measured on magnetic resonance imaging. Knee laxity was assessed using the pivot-shift test and stress radiography.

RESULTS

In the posterior TS group, the femoral tunnel was usually located deeper on the X-axis and more superior on the Y-axis, which corresponds to a more proximal position, than in the anterior group (deeper on the X-axis and superior on the Y-axis). Moreover, the femoral tunnel locations in this group were more compactly distributed than those in the anterior group. The TS group showed significantly better reduction of postoperative PATS in the lateral compartments than the anterior group (anterior group vs. TS group: lateral compartment, 3.2 ± 3.1 vs. 4.5 ± 3.2 mm; p = .016). Significantly better results were found in the TS group for knee stability as assessed by the pivot-shift grade (p = .044); however, there were no significant differences between the two groups with respect to patient-reported outcome measures (p > .05) and other complications (p = .090).

CONCLUSION

Our results suggest that positioning the femoral tunnel using the posterior TS portal approach may lead to better outcomes in terms of PATS and rotational stability compared to the anterior portal approach in ACLR.

Combined Anterolateral Ligament Reconstruction Results in Better Knee Stability and More Satisfactory Subjective Outcomes in Non-Athlete Patients Undergoing Revision Anterior Cruciate Ligament Reconstruction

Background: Consensus has not yet been reached regarding combined anterior cruciate ligament reconstruction (ALLR) with revisional anterior cruciate ligament reconstruction (RACLR). We aimed to compare the clinical outcomes between patients who underwent isolated RACLR and those who underwent RACLR combined with ALLR. Methods: Between June 2010 and June 2021, 49 patients who underwent RACLR were retrospectively reviewed over a 24-month follow-up. Patients were categorized into the isolated RACLR (n = 37, group 1) or combined ALLR group (n = 12, group 2). Clinical outcomes were evaluated with several patient-reported outcome measures (PROMs) and minimal clinically important differences (MCIDs) for each PROM. The side-to-side difference (SSD) of the anterior instability was measured. The pivot-shift test was performed. Results: Baseline characteristics showed no differences between the groups. PROMs showed no significant differences between the groups at the 2-year follow-up. Group 2 was superior to group 1 in the MCID achievement rate for Lysholm knee and International Knee Documentation Committee (IKDC) subjective scores at 24 months postoperatively. At the final follow-up, the proportion of IKDC grade A in SSD for anterior laxity was higher in group 2 than in group 1 (58.3% versus [vs.] 18.3%, p = 0.009), and the proportion of pivot-shift grade 0 was also higher in group 2 (66.7% vs. 27.0%, p = 0.013). The "near return to activity" rate was also higher in group 2 than in group 1 (83.3% vs. 45.9%, p = 0.043). Conclusions: Combining ALLR with RACLR in non-athletes results in a higher proportion of patients with less mechanical graft failure and satisfactory clinical outcomes.

Development of an Original Three-Dimensional Computed Tomography Scan Method and Imaging Process for Surgical Support of the Anterior Cruciate Ligament

Three-dimensional computed tomography (3D CT) scan images are useful as they can provide information essential for surgical support, particularly in orthopedic surgery. In the case of anterior cruciate ligament (ACL) reconstruction, a 3D CT scan is important in preoperative simulation. Furthermore, it is associated with a reduced risk of revision surgery because the angle of the foramen magnum changes with the femoral muscle mass. However, the CT scan system geometry has several limitations. For example, the patient's posture is limited during the procedure. Herein, we report an original CT scan method and 3D imaging process for surgical support of the ACL.

Small Intercondylar Notch Size Is Not Associated with Poor Surgical Outcomes of Anatomical Single-Bundle Anterior Cruciate Ligament Reconstructions

Background

Although many studies have been conducted on the association between the intercondylar notch size and the risk of anterior cruciate ligament (ACL) injury, few studies have examined its relationship with the condition after surgical treatment. Therefore, this study aimed to investigate the surgical outcomes of anatomical single-bundle ACL reconstruction according to intercondylar notch volumes.

Methods

Medical records of patients who underwent anatomical single-bundle ACL reconstruction using a tibialis anterior allograft between 2015 and 2019 were retrospectively reviewed. For each sex, eligible patients were classified into two groups based on their percentile of intercondylar notch volumes, which were measured using postoperative three-dimensional computed tomography images (group S, ≤ 50th percentile of included patients; group L, > 50th percentile of included patients). Additional grouping was performed based on the group's percentiles of normalized values of intercondylar notch volumes to body heights. Between-group comparative analyses were performed on the perioperative data and surgical outcomes in both objective and subjective aspects.

Results

One hundred patients were included in the study. For male patients, there were no differences in the overall surgical outcomes between groups, whereas group L showed a significantly greater knee anteroposterior (AP) laxity than group S at the final follow-up (p = 0.042 for the side-to-side differences [SSD] at the maximum manual force). Similarly, there were no differences in the female patients in the overall surgical results between the groups, whereas group L showed a significantly greater knee AP laxity at the final follow-up (p = 0.020 for the SSD at 134 N; p = 0.011 for the SSD at the maximum manual force). Additional analyses based on the normalized values of the intercondylar notch volume showed consistent results for male patients, and additional grouping for female patients was identical to the existing grouping.

Conclusions

The surgical outcomes of anatomical single-bundle ACL reconstruction in patients with relatively small intercondylar notch volumes were comparable to those with large notch volumes, but rather showed favorable outcomes in postoperative knee AP laxity.

Distribution of bone tunnel positions and treatment efficacy of bone landmark positioning method for anatomical reconstruction of the anterior cruciate ligament: a case control study

BACKGROUND

This study aimed to investigate the distribution of femoral tunnel and explore the influences of bone tunnel positions on knee functions. The bone landmark positioning method was used to position the femoral tunnel during the anatomical reconstruction surgery in patients with anterior cruciate ligament (ACL) rupture.

METHODS

Data of patients who underwent anatomical reconstruction of the ACL between January 2015 and July 2018, were retrospectively analyzed. The distribution of the femoral tunnel was recorded on 3-D CT after surgery. The tunnel positions were classified into good and poor position groups based on whether the position was in the normal range (24-37% on the x-axis and 28-43% on the y-axis). The Lysholm and IKDC scores, KT-1000 side-to-side difference, pivot shift test and Lachman test results of the knee joints were recorded, and then the differences in knee joint functions between the two groups were analyzed.

RESULTS

84 eligible patients (84 knees) were finally included in this study. Twenty-two and 62 of the patients were categorized in the good and poor position groups, respectively, and the rate of good position was 26.2%. The distribution of bone tunnel was as follows: (x-axis) deep position in 10 patients (12%), normal position in 58 patients (69%), and shallow position in 16 patients (19%); (y-axis) high position in 54 patients (64%), normal position in 26 patients (31%), and low position in 4 patients (5%). 1 year later, the Lysholm and IKDC scores were significantly better in the good position group (P < 0.05), the KT-1000 side to side difference, the pivot shift test and Lachman test results were better in the good position group (P < 0.05).

CONCLUSIONS

The bone tunnels were found to be distributed in and beyond the normal range using the bone landmark method to position the femoral tunnel in the single-bundle anatomical reconstruction of ACL, while the rate of good bone tunnel position was low. The knee joint function scores and stability were lower in patients with poor position of the femoral tunnel.

The apex of the deep cartilage is a stable landmark to evaluate the femoral tunnel position in ACL reconstruction

PURPOSE

To develop a simple and effective method for evaluating the femoral tunnel position using the apex of the deep cartilage (ADC) as the landmark.

METHODS

A total of 52 patients who underwent arthroscopic ACL reconstruction were recruited between June and September 2021. The femoral tunnel was placed on the central point of the anteromedial footprint with an accessory anteromedial and a high anterolateral portal. Then, the length from the ADC to the shallow cartilage margin (L₁) and to the center of the femoral tunnel (l₁), as well as the center to the low cartilage margin (H₁, intraoperative height), was measured under arthroscopy and on postoperative CT scans (L₂, l₂ and H₂). Moreover, intraoperative and postoperative cartilage ratios were equivalent to l₁/L₁ and l₂/L₂, respectively. Linear regression, Pearson correlation and Bland-Altman analysis were performed to evaluate the consistency between these two measurements of cartilage ratio (l/L) and height (H).

RESULTS

The mean age at the time of surgery was 28.7 years; 42 patients were male, and 17 patients were hurt in the left knee among 52 patients. The intraoperative cartilage ratio was 0.37 ± 0.04, and the height was 8.1 ± 1.1 mm with almost perfect inter-observer reproducibility. After the surgery, the cartilage ratio and height were measured as 0.39 ± 0.04 and 8.2 ± 1.3 mm on 3D-CT, respectively, with almost perfect intra- and inter-observer reproducibility. Significant positive correlations and linear regression were detected in the cartilage ratio (r = 0.844, p < 0.001), and height (r = 0.926, p < 0.001) intraoperatively and postoperatively. The Bland-Altman plot also showed excellent consistency between arthroscopy and 3D-CT.

CONCLUSIONS

The ADC is a good landmark in the assessment of femoral tunnel position, with excellent consistency between intraoperative arthroscopic measurements and postoperative 3D-CT.

CLINICALTRIALS

gov Identifier: NCT04937517.

LEVEL OF EVIDENCE

Level III.

The orientation of the ALL femoral tunnel to minimize collision with the ACL tunnel depends on the need or not of far-cortex drilling

PURPOSE

To (1) evaluate the optimal drill orientation of the anterolateral ligament (ALL) femoral tunnel to minimize collision with the anterior cruciate ligament (ACL) femoral tunnel during anatomical ACL reconstruction according to the need for far-cortex drilling and (2) investigate the geometric factors that affect tunnel collision secondary to drill orientation of the ALL femoral tunnel.

METHODS

A three-dimensional femoral model of patients who underwent anatomical single-bundle ACL reconstruction between 2015 and 2016 was constructed, and the geometric factors were evaluated. Virtual ALL femoral tunnels were created to simulate 45 drilling conditions. For each condition, whether the virtual ALL femoral tunnel and its trajectory violated the femoral cortex and the minimum distance between tunnels was investigated.

RESULTS

Thirty-nine subjects were included. Overall violation rates of the femoral cortex by the ALL tunnels and its trajectories were 11.1% (195 of 1755 conditions) and 40.7% (714 of 1755 conditions), respectively. A drilling angle of axial 0° and coronal - 40° showed the longest minimum distance between tunnels without femoral cortex violation by the ALL tunnel (6.3 ± 4.0 mm; collision rate 2.6% [1 of 39 subjects]). With simultaneous consideration of the ALL tunnel's trajectory representing far-cortex drilling, a drill angle of axial 40° and coronal 10° showed the longest minimum distance between tunnels without femoral cortex violation (0.6 ± 3.9 mm; collision rate 38.5% [15 of 39 subjects]). For surgical techniques requiring far-cortex drilling, regression analyses were performed on geometric factors that could affect tunnel collision, which revealed that the sagittal inclination angle of the ACL and the distance between the ACL femoral tunnel's outlet and ALL's femoral attachment were associated with tunnel collision.

CONCLUSION

The optimal drill orientations of the ALL femoral tunnel to minimize collision with the ACL femoral tunnel were axial 0° and coronal - 40° for surgical techniques not requiring far-cortex drilling and axial 40° and coronal 10° for techniques requiring far-cortex drilling. For techniques requiring far-cortex drilling, additional adjustment for orientation of the ACL femoral tunnel is required to reduce the risk of tunnel collision. Therefore, an individualized surgical strategy should be applied according to the graft fixation method of the ALL femoral tunnel.

Eccentrically widened bone tunnels after all-inside anterior cruciate ligament reconstruction: a computed tomography and three-dimensional model-based analysis

PURPOSE

To evaluate the extent of tunnel widening after anterior cruciate ligament reconstruction (ACLR) using the all-inside technique and to establish its correlation with patient-reported clinical outcomes and femoral graft bending angle (GBA).

METHODS

Tunnel widening was evaluated using computed tomography (CT)-based three-dimensional (3D) models, and the femoral GBA was directly measured on CT images using the Picture Archiving and Communication System (PACS) software. Clinical follow-up was routine procedure, and patient-reported clinical outcomes mainly included International Knee Documentation Committee (IKDC), Lysholm, and Knee Injury and Osteoarthritis Outcome Scores (KOOS) scores, and subjective knee stability assessment.

RESULTS

Fifty-two patients received standard all-inside ACLR, with a median follow-up of 6 months. Reconstructed anterior cruciate ligaments (ACLs) were scanned during the first 3 days and 6 months after surgery. On both the femoral and tibial sides, bone tunnels were most significantly enlarged at the articular aperture segment; the femoral tunnel was 9.2 ± 1.3 mm postoperatively and was significantly enlarged by 32% to a mean tunnel diameter of 12.1 ± 2.0 mm at 6 months after surgery. Moreover, the extent of tunnel enlargement gradually decreased as the measured levels approached those of the bone cortex. The femoral tunnel center was shifted into the anterior and distal direction, and the tibial tunnel center was shifted into the posterior and lateral direction. Additionally, the mean femoral GBA was 105.9° ± 8.1° at the 6-month follow-up. Tunnel enlargement and GBA were not significantly correlated with patient-reported outcomes.

CONCLUSIONS

Femoral and tibial tunnels were significantly greater and eccentrically shifted at the 6-month follow-up after all-side ACLR. However, the extent of tunnel widening does not markedly affect the short-term clinical outcomes. Meanwhile, the femoral GBA was not significantly correlated with femoral tunnel widening or patient-reported outcomes. Although the tunnel widening following all-inside ACLR was not associated with clinical outcomes, it potentially caused difficulties in revision ACLR.

LEVEL OF EVIDENCE

Level IV.

Graft isometry during anatomical ACL reconstruction has little effect on surgical outcomes

PURPOSE

To investigate the surgical outcomes of anatomical anterior cruciate ligament (ACL) reconstruction according to the graft isometry measured during surgery.

METHODS

Electrical medical records of patients who underwent an arthroscopic ACL reconstruction through the transportal technique using hamstring tendon autograft between 2012 and 2016 were retrospectively reviewed. The patients were classified into two groups based on the graft length change throughout the knee range of motion measured just before graft fixation (Group 1, graft length change ≤ 2 mm; Group 2, graft length change > 2 mm). Comparative analyses, including a non-inferiority trial, were performed regarding the clinical scores, knee laxity, and radiographic parameters between the groups.

RESULTS

A total of 67 patients were included in the study. The total change in the length of ACL graft throughout the knee range of motion was 1.4 ± 0.4 mm in Group 1 (range, 0.2-2.0 mm), and 3.0 ± 0.7 mm in Group 2 (range, 2.2-5.0 mm). Group 1 showed a relatively high (proximal) femoral tunnel and shallow (anterior) tibial tunnel compared to Group 2 (P < 0.001 and P = 0.028, respectively), but there were no apparent differences in the macroscopic view. There were no statistically significant differences in the clinical outcomes between groups at 2 years after surgery, which satisfied the non-inferiority criterion of Group 1 in terms of clinical scores and knee laxity compared to Group 2.

CONCLUSION

The surgical outcomes of anatomical ACL reconstruction in patients with non-isometric ACL graft were not inferior in terms of clinical scores and knee laxity, compared to those with nearly-isometric ACL graft. The graft tunnel placement in the isometric position during anatomical ACL reconstruction, which is technically challenging in the clinical setting, is not a crucial factor in terms of clinical outcomes.

LEVEL OF EVIDENCE

Level IV.

What Is the Maximum Tibial Tunnel Angle for Transtibial PCL Reconstruction? A Comparison Based on Virtual Radiographs, CT Images, and 3D Knee Models

BACKGROUND

To minimize the killer turn caused by the sharp margin of the tibial tunnel exit in transtibial PCL reconstruction, surgeons tend to maximize the angle of the tibial tunnel in relation to the tibial plateau. However, to date, no consensus has been reached regarding the maximum angle for the PCL tibial tunnel.

QUESTIONS/PURPOSES

In this study we sought (1) to determine the maximum tibial tunnel angle for the anteromedial and anterolateral approaches in transtibial PCL reconstruction; (2) to compare the differences in the maximum angle based on three measurement methods: virtual radiographs, CT images, and three-dimensional (3D) knee models; and (3) to conduct a correlation analysis to determine whether patient anthropomorphic factors (age, sex, height, and BMI) are associated with the maximum tibial tunnel angle.

METHODS

Between January 2018 and December 2020, 625 patients who underwent CT scanning for knee injuries were retrospectively reviewed in our institution. Inclusion criteria were patients 18 to 60 years of age with a Kellgren-Lawrence grade of knee osteoarthritis less than 1 and CT images that clearly showed the PCL tibial attachment. Exclusion criteria were patients with a history of tibial plateau fracture, PCL injuries, tumor, and deformity around the knee. Finally, 104 patients (43 males and 61 females, median age: 38 [range 24 to 56] years, height: 165 ± 9 cm, median BMI: 23 kg/cm2 [range 17 to 31]) were included for analysis. CT data were used to create virtual 3D knee models, and virtual true lateral knee radiographs were obtained by rotating the 3D knee models. Virtual 3D knee models were used as an in vitro standard method to assess the true maximum tibial tunnel angle of anteromedial and anterolateral approaches in transtibial PCL reconstruction. The tibial tunnel's entry was placed 1.5 cm anteromedial and anterolateral to the tibial tubercle for the two approaches. To obtain the maximum angle, a 10-mm- diameter tibial tunnel was simulated by making the tibial tunnel near the posterior tibial cortex. The maximum tibial tunnel angle, tibial tunnel lengths, and perpendicular distances of the tunnel's entry point to the tibial plateau were measured on virtual radiographs, CT images, and virtual 3D knee models. One-way ANOVA was used to compare the differences in the maximum angle among groups, and correlation analysis was performed to identify the relationship of the maximum angle and anthropomorphic factors (age, sex, height, and BMI).

RESULTS

The maximum angle of the PCL tibial tunnel relative to the tibial plateau was greater in the anteromedial group than the anterolateral group (58° ± 8° versus 50° ± 8°, mean difference 8° [95% CI 6° to 10°]; p < 0.001). The maximum angle of the PCL tibial tunnel was greater in the virtual radiograph group than the CT image (68° ± 6° versus 49° ± 5°, mean difference 19° [95% CI 17° to 21°]; p < 0.001), the anteromedial approach (68° ± 6° versus 58° ± 8°, mean difference 10° [95% CI 8° to 12°]; p < 0.001), and the anterolateral approach (68° ± 6° versus 50° ± 8°, mean difference 18° [95% CI 16° to 20°]; p < 0.001), but no difference was found between the CT image and the anterolateral groups (49° ± 5° versus 50° ± 8°, mean difference -1° [95% CI -4° to 1°]; p = 0.79). We found no patient anthropomorphic characteristics (age, sex, height, and BMI) that were associated with the maximum angle.

CONCLUSION

Surgeons should note that the mean maximum angle of the tibial tunnel relative to the tibial plateau was greater in the anteromedial than anterolateral approach in PCL reconstruction, and the maximum angle might be overestimated on virtual radiographs and underestimated on CT images.

CLINICAL RELEVANCE

To perform PCL reconstruction more safely, the findings of this study suggest that the PCL drill system should be set differently for the anteromedial and anterolateral approaches, and the maximum angle measured by intraoperative fluoroscopy should be reduced 10° for the anteromedial approach and 18° for the anterolateral approach. Future clinical or cadaveric studies are needed to validate our findings.

The Graft Insertion Length in the Femoral Tunnel During Anterior Cruciate Ligament Reconstruction With Suspensory Fixation and Tibialis Anterior Allograft Does Not Affect Surgical Outcomes but Is Negatively Correlated With Tunnel Widening

PURPOSE

To investigate the surgical outcomes of anterior cruciate ligament (ACL) reconstruction using a low-dose irradiated tibialis anterior allograft with a fixed-loop cortical suspension device for the femur based on the graft insertion length (GIL) in the femoral tunnel.

METHODS

Between January 2010 and January 2018, the medical records of consecutive patients who underwent arthroscopic ACL reconstruction with a tibialis anterior allograft fixed with the EndoButton CL for the femur and who had at least 2 years of follow-up were retrospectively evaluated. Patients were classified into 3 groups based on the GIL in the femoral tunnel (group 1, GIL < 15 mm; group 2, GIL of 15-20 mm; and group 3, GIL > 20 mm), and their functional scores, knee laxity, and radiographic parameters were evaluated.

RESULTS

A total of 91 patients were analyzed. There were no statistically significant differences in the functional scores and knee laxity between the 3 groups at 2 years postoperatively. However, significant differences were observed in tunnel widening at 1 year postoperatively in the femur (P = .045 for absolute value and P = .004 for relative value) and the tibia (P = .014 for absolute value and P = .012 for relative value), revealing that both the femoral and tibial tunnels widened as the GIL decreased. Additional linear regression analyses were performed to identify whether the GIL independently affects tunnel widening. Consequently, the femoral tunnel depth, tunnel diameter, and GIL were found to independently influence femoral tunnel widening (P = .008, P = .019, and P < .001, respectively), whereas the tunnel diameter and GIL affected tibial tunnel widening (P < .001 and P = .004, respectively).

CONCLUSIONS

The GIL in the femoral tunnel during ACL reconstruction using a tibialis anterior allograft with a fixed-loop cortical suspension device for the femur has no significant association with the postoperative functional outcomes and knee laxity, but it has a negative correlation with tunnel widening in the femur and the tibia.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Does radiological evaluation of endobutton positioning in the sagittal plane affect clinical functional results in single-bundle anterior cruciate ligament reconstruction?

INTRODUCTION

Sports injuries are increasing today due to the increased interest in sports. The most common injured knee ligament is the anterior cruciate ligament (ACL) in sport injuries. Accordingly, surgical treatment of the ACL is performed frequently. In this study, it was aimed to retrospectively evaluate whether the location of an endobutton on lateral knee radiography was effective on knee functional scores in patients who underwent ACL reconstruction.

MATERIALS AND METHODS

One hundred thirty patients who underwent ACL reconstruction between January 2015 and February 2019 were identified. The patients were divided into three groups according to the location of the endobutton on lateral radiographs taken in the postoperative period. Group 1 patients were classified as anterior, group 2 as middle, and group 3 as posterior according to the location of the endobutton. Functional scoring, physical examination tests, comparative thigh diameter measurements, and single-leg hop tests were compared between the groups. It was evaluated as to whether there was a statistically significant difference between the groups.

RESULTS

There were 38 patients in group 1, 63 patients in group 2, and 29 patients in group 3. The mean age was 29.1 in group 1, 29.1 in group 2, and 29.7 in group 3. The mean follow-up period of the patients was 18.4 months in group 1, 19.1 months in group 2, and 21.4 months in group 3. The average Lysholm score was 92.9 in group 1, 93.3 in group 2, and 91.7 in group 3. The mean modified Cincinnati scores were 27.0, 27.1, and 26.6, respectively, in the groups. The mean IKDC score of the subjective knee assessments was 92.5, 92.8, and 91, respectively, according to the groups. The average thigh atrophy value was 1 cm, 1 cm, and 1.2 cm, respectively, in the groups. In the single-leg hop test, 34 patients in group 1 jump to over 85% of the distance compared with the intact side, while 58 patients in group 2, and 23 patients in group 3 were successfully able to jump this distance. The effect of the placement of the endobutton in the anterior, middle or posterior was not statistically significant on functional scores and physical examination results. In patients with endobuttons in the middle, functional scores were found better than in those with anterior or posterior placement.

CONCLUSIONS

No statistically significant differences were found in clinical functional results when comparing patients' endobutton location on femur. For this reason, surgical time should not be extended using unnecessary extra effort to change the orientation of the exit hole during surgery.

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.

The location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology

PURPOSE

The purpose of this study was to evaluate the difference in the center point of the femoral ACL footprint according to the morphological variations of the Blumensaat's line.

METHODS

Fifty-nine non-paired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. Digital images were evaluated using the Image J software. The periphery of the femoral ACL footprint was outlined and the center point was measured automatically. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill types (small and large hill types). The center of the femoral ACL footprint and hilltop placement were evaluated using the quadrant method. A quadrant grid was placed uniformly, irregardless of hill existence, and not including the articular cartilage. A correlation analysis was performed between the center point of the femoral ACL footprint and hilltop placement.

RESULTS

The straight type consisted of 19 knees, and the hill type 40 knees (small hill type 13 knees and large hill type 27 knees). The center of the femoral ACL footprint (shallow-deep/high-low) in the straight and hill type knees was 33.7/47.6%, and 37.2/50.3%, respectively. In the hill type, the ACL footprint center was significantly more shallow when compared to the straight type. Significant correlation was observed between the center point of the femoral ACL footprint and hilltop placement of the Blumensaat's line.

CONCLUSION

The center point of the femoral ACL footprint was significantly more shallow in the hill type knees when compared to the straight type. For clinical relevance, considering that the location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology, to perform accurate ACL reconstruction, femoral ACL tunnel placement should be made based on Blumensaat's line morphological variations.