Three dimensionalCT analysis of femoral tunnel position after ACL reconstruction. A prospective study of one hundred and thirty five cases

3D assessment of graft malposition after ACL reconstruction: Comparison of native and 11o'clock ligament orientations

BACKGROUND

Femoral tunnel malposition makes up the majority of technical failures for ACL reconstructive surgery. The goal of this study was to develop adolescent knee models that accurately predict anterior tibial translation when undergoing a Lachman and pivot shift test with the ACL in the 11o'clock femoral malposition (Level of Evidence: IV).

METHODS

FEBio was used to build 22 subject-specific tibiofemoral joint finite element representations. To simulate the two clinical tests, the models were subject to loading and boundary conditions established in the literature. Clinical, historical control data were used to validate the predicted anterior tibial translations.

RESULTS

A 95% confidence interval showed that with the ACL in the 11o'clock malposition, the simulated Lachman and pivot shift tests produced anterior tibial translations that were not statistically different from the in vivo data. The 11o'clock finite element knee models resulted in greater anterior displacement than those with the native (approximately 10o'clock) ACL position. The difference in anterior tibial translation between the native and 11o'clock ACL orientations was statistically significant.

CONCLUSION

Clinically, by understanding the impact that ACL orientation has in anterior tibial displacement biomechanics, surgical interventions can be improved to prevent technical errors from occurring. The integration of this methodology into surgical practice not only allows for anatomical visualization prior to surgery, but also creates the opportunity to optimize graft placement, thus improving post-surgical outcomes.

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.

Femoral Intercondylar Notch: Gross Anatomy and Histology of the Connective Tissue Lining of its Roof: A Pilot Study

PURPOSE

We have consistently observed a connective tissue lining over the intercondylar notch's roof (CTLINR) during arthroscopic surgeries of the knee joint. As there is a strong association of the intercondylar fossa with the anterior cruciate ligament (ACL), we believe that this tissue must be having some role in the functioning of the ACL. The purpose of this pilot study was to investigate the anatomic characteristics of the CTLINR.

METHODS

In this observational anatomical study, we have investigated the gross anatomical and histological features of the CTLINR in four knees of two fresh frozen non-embalmed cadavers. We have also studied its ultrastructural characteristics by obtaining an arthroscopic biopsy of the tissue from a patient undergoing ACL reconstruction.

RESULTS

At gross examination, the CTLINR had a typical glistening white surface with transversely oriented fibres. It entirely covered the roof of the intercondylar notch and was soft to touch. Histological examination with haematoxylin-eosin stain revealed fibro-collagenous tissue with intervening blood vessels. Transmission electron microscopy manifested loosely arranged collagen fibres of variable diameter.

CONCLUSION

The histological and electron microscopic characteristics of the tissue differentiate it from the ACL and its femoral enthesis, suggesting that it was a distinct anatomical structure. As it entirely covered the roof of the intercondylar fossa and had a smooth surface and soft consistency, it may protect the reconstructed ACL from graft abrasion. Furthermore, as it had a characteristic arthroscopic appearance, future research can investigate its role in femoral tunnel positioning.

The sagittal cutting plane affects evaluation of the femoral bone tunnel position on three-dimensional computed tomography after anterior cruciate ligament reconstruction

PURPOSE

To investigate how the femoral sagittal cutting plane affects evaluation of the bone tunnel position after anterior cruciate ligament (ACL) reconstruction using the quadrant method in three-dimensional computed tomography (CT) imaging.

METHODS

Thirty patients who underwent primary anatomic double-bundle ACL reconstruction and CT 2 weeks after surgery were enrolled. Three sagittal cutting planes with respect to the condylar axis were created using the CT images: at the top of the intercondylar notch (C-plane), 5% medial (M-plane), and 5% lateral (L-plane). The center of the bone tunnel position regarding depth and height of the anteromedial (AMB) and posterolateral bundle (PLB) were quantitatively evaluated using the quadrant method on the three different planes.

RESULTS

The mean depths of AMB and PLB were 27.4 ± 4.4% and 39.7 ± 5.1%, 27.0 ± 4.2% and 37.6 ± 4.9%, and 27.4 ± 4.5% and 38.5 ± 6.0%, at the M, C and L planes, respectively. The mean heights of AMB and PLB were 30.8 ± 6.3% and 56.2 ± 5.6%, 30.4 ± 6.2% and 56.6 ± 5.6%, and 25.4 ± 7.0% and 52.9 ± 6.9% at the M, C, and L planes, respectively. Both AMB and PLB bone tunnels were evaluated as higher positions in the L-plane than the C-plane (p < 0.01, p = 0.02, respectively) and M-plane (p < 0.01, p = 0.04, respectively), but there were no significant differences between the C-plane and M-plane (n.s.). There was no significant difference in the anteroposterior direction for all planes.

CONCLUSION

In evaluations of the bone tunnel position with the quadrant method using three-dimensional CT, the bone tunnel position depends on the femoral sagittal cutting plane. A consistent evaluation method should be used when evaluating the bone tunnel position after ACL reconstruction to enable correct evaluation clinically.

LEVEL OF EVIDENCE

Case-control study, Level III.

Dual fluoroscopic imaging and CT-based finite element modelling to estimate forces and stresses of grafts in anatomical single-bundle ACL reconstruction with different femoral tunnels

PURPOSE

Little is known about the in vivo forces and stresses on grafts used in anterior cruciate ligament (ACL) reconstruction. The aims of this study were to evaluate and compare the forces and stresses on grafts used in anatomical single-bundle ACL reconstruction at different locations of the femoral footprint (anterior vs middle vs posterior; high vs middle vs low) during a lunge motion.

METHODS

Establish subject-specific finite element models with different graft's tunnel loci to represent the primary ACL reconstructions. A displacement controlled finite element method was used to simulate lunge motions (full extension to ~ 100° of flexion) with six-degree-of-freedom knee kinematics data obtained from the validated dual fluoroscopic imaging techniques. The reaction force of the femur and maximal principal stresses of the grafts were subsequently calculated during knee flexion.

RESULTS

Increased and decreased graft forces were observed when the grafts were located higher and lower on the femoral footprint, respectively; anterior and posterior graft placement did not significantly affect the graft force. Lower and posterior graft placement resulted in less stress on the graft at higher degrees of flexion; there were no significant differences in stress when the grafts were placed from 0° to 30° of flexion on the femoral footprint.

CONCLUSION

The proposed method is able to simulate knee joint motion based on in vivo kinematics. The results demonstrate that posterior to the centre of the femoral footprint is the strategic location for graft placement, and this placement results in anatomical graft behaviour with a low stress state.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The unhappy triad of the knee re-revisited

AIM OF THE STUDY

To describe the surgical findings of the anterolateral complex in patients with the "unhappy triad" lesion of the knee.

METHOD

One hundred and twenty-five consecutive patients presenting with acute anterior cruciate ligament (ACL) tears were selected for this study. Only cases, evaluated with a valgus stress test under fluoroscopy, with a medial opening more than 5 mm of the medial collateral ligament (MCL) were included in the study (11 patients). For the included cases, open MCL surgical repair was performed only in cases with a valgus stress test more than 10 mm as revealed by fluoroscopy (3 patients). All included cases (11 patients) underwent ACL reconstruction and exploration of the anterolateral complex that was then assessed, photographed, classified, and eventually repaired.

RESULTS

At clinical evaluation under anaesthesia, all patients presented a positive Lachman test and a pivot shift test graded as ++ in four cases and +++ in five cases, not valuable in two cases. At surgical exploration, the anterolateral complex was involved in all cases (11 patients): one case demonstrated a type I injury, eight cases a type II injury, two cases a type III injury, and no patient with a type IV injury (Segond's fracture). All anterolateral complex lesions were repaired by direct suture and re-tensioning.

DISCUSSION

On the basis of a recent analysis performed by other authors, we could speculate that injuries of ACL and anterolateral compartment occur in the very early phase of the injury when the knee is forced into internal rotation. The MRI evidence of bone bruising in the lateral compartment in most cases of the present series support the hypothesis of an internal rotation torque.

CONCLUSIONS

The unhappy triad of injuries to the knee is actually a tetrad involving not just the ACL, MCL, and medial/lateral meniscus but also involved the anterolateral complex.