The relationship between graft intensity on MRI and tibial tunnel placement in anatomical double-bundle ACL reconstruction

Quadriceps Tendon With Bone Autograft Has Better Stability and Magnetic Resonance Imaging Maturation Than Hamstring Tendon Autograft After Anterior Cruciate Ligament Reconstruction in Patients With Knee Hyperextension

PURPOSE

To compare the clinical outcomes of anterior cruciate ligament (ACL) reconstruction between methods using quadriceps tendon with bone (QTB) and hamstring tendon (HT) in patients with hyperextension of the knee.

METHODS

The medical records of patients with knee hyperextension greater than 8° who underwent arthroscopic ACL reconstruction between October 2010 and October 2020 with follow-up for at least 2 years (median, 3 years; interquartile range [IQR], 2.0-4.6 years) were retrospectively reviewed. Side-to-side difference in anterior translation, pivot-shift test grade, Lysholm score, and graft intensity using the Howell grade on magnetic resonance imaging at final follow-up were compared between the QTB and HT groups.

RESULTS

The HT and QTB groups consisted of 42 patients and 21 patients, respectively. The overall mean age was 21.5 years (range, 14-48 years), and the median Tegner Activity Scale score was 6 (range, 3-9). Postoperatively, the median side-to-side difference in anterior translation was 1.75 mm (IQR, 1-3 mm) in the HT group and 1.0 mm (IQR, 0-1.75 mm) in the QTB group (P = .01). Pivot-shift testing showed grade 0 in 74.7%, grade 1 in 18.7%, and grade 2 in 6.6% of patients in the HT group and grade 0 in 85.7% and grade 1 in 14.3% of those in the QTB group (P = .03). The median postoperative Lysholm score was 99 in both groups. Graft signal intensity showed a significant between-group difference: grade I in 52%, grade II in 36%, and grade III in 12% of patients in the HT group versus grade I in 85.7%, grade II in 9.5%, and grade III in 4.8% of those in the QTB group (P = .03).

CONCLUSIONS

In patients who underwent ACL reconstruction for hyperextension of the knee, QTB yielded better clinical outcomes than HT with respect to anterior stability, rotational stability, and graft signal intensity on median 2-year follow-up magnetic resonance imaging.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Graft impingement increases anterior cruciate ligament graft signal more than acute graft bending angle: magnetic resonance imaging-based study in outside-in anterior cruciate ligament reconstruction

PURPOSE

In this study, the relationship between patient-specific geometric factors and tunnel placement in graft impingement was identified by using magnetic resonance imaging (MRI) signal intensity of anterior cruciate ligament (ACL) grafts.

METHODS

Ninety-two patients, who were treated between 2014 and 2020, were included retrospectively. These patients underwent primary remnant-preserving outside-in ACL reconstruction (ACLR) and were followed up with postoperative MRI at least one year after surgery. Plain radiographs and computed tomography (CT) were used to analyze tibial and femoral tunnel positions. Postoperative MRI was performed, at 32.8 ± 17.5 months after surgery, to evaluate the graft signal intensity, the ACL/posterior cruciate ligament (PCL) ratio (APR), ACL/muscle ratio (AMR), tunnel positions, and graft impingement. Clinical and stability outcomes were analyzed using the International Knee Documentation Committee (IKDC) subjective and objective scores, Lysholm scores, and side-to-side differences (SS-D).

RESULTS

The mean APR and AMR of the proximal third of the grafts were significantly lower than those of the middle third of the grafts (p = 0.017 and p = 0.045, respectively). Multivariate regression analysis showed that there was a negative association between the mean APR and AMR of entire intra-articular ACL graft and the distance from the anterior end of the intercondylar roof to the center of the tibial tunnel in the sagittal plane (p < 0.001 and p < 0.001, respectively) and the notch width index (p < 0.001 and p = 0.002, respectively). No significant correlations were found between tunneling and geometric factors, and clinical scores or SS-D.

CONCLUSIONS

Graft impingement on the anterior tibial tunnel relative to the end of the intercondylar roof and narrow notch was a more significant contributing factor on increased signal intensities of the ACL graft, compared with the acute femoral bending angle in remnant-preserving outside-in ACLR. Therefore, surgeons should focus on intercondylar notch anatomy during tibial tunnel placement to avoid roof impingement.

LEVEL OF EVIDENCE

Level III.

Use of oblique sagittal and coronal weighted images for diagnosis and grading of ACL graft injury

Background

This study was done to evaluate the value of adding the oblique sagittal and oblique coronal MRI to the standard MRI knee protocol for evaluation of suspected ACL graft injuries.

Results

This was a cross-sectional analytic study where we reviewed 36 MRI knee examinations of 36 patients (30 males, 6 females, age range: 17–60 years, mean age: 26 years) who were subjected to ACL reconstruction and follow-up arthroscopy. Two experienced radiologists, blinded to the results of each other, evaluated the status and the severity of the ACL graft injury using the routine knee MRI (protocol A) and using the routine MRI after adding the oblique sagittal and coronal imaging (protocol B). Weighted kappa statistics were used to evaluate the diagnostic accuracies of the knee MRI before and after the addition of the oblique sagittal and coronal weighted images (protocol A and protocol B, respectively) and to assess the interobserver agreement. The weighted kappa values according to the routine knee MRI were 0.357 (reader 1) and 0.399 (reader 2). The inclusion of additional oblique coronal imaging increased the weighted kappa values to 0.505 (reader 1) and 0.528 (reader 2). The interobserver agreement weighted kappa value also increased from 0.606 to 0.759 by adding the oblique sagittal and coronal imaging to the routine knee MRI examination.

Conclusion

The additional use of oblique sagittal and coronal MRI of the knee improves the diagnostic accuracy for diagnosing and grading ACL graft injury with the arthroscopy used as a gold standard.

Increased Posterior Tibial Slope Is Associated With Greater Risk of Graft Roof Impingement After Anatomic Anterior Cruciate Ligament Reconstruction

BACKGROUND

Increased posterior tibial slope (PTS) has been reported to be associated with irreducible anterior tibial subluxation in extension after anatomic anterior cruciate ligament (ACL) reconstruction (ACLR), which raises concerns about the greater risk of graft roof impingement (GRI) although the tibial tunnel is positioned anatomically.

HYPOTHESIS

Increased PTS would be associated with greater risk of GRI after anatomic ACLR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Between January 2016 and December 2017, a total of 418 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary anatomic ACLR. Among them, 26 patients had ≥1 of the following features during the second-look arthroscopy: fractured/guillotined bundles at the tibial insertion or cyclops lesion. These patients were confirmed to have GRI and were allocated to the study group. They were also matched 1:2 to 52 control participants without GRI. PTS was measured on true lateral whole-leg radiographs. Intra-articular ACL graft signal intensity was evaluated on postoperative magnetic resonance imaging scans (mean, 32.8 months; range, 26-38 months) and divided into 3 grades (I, good; II, moderate; III, poor) based on degree of GRI. Moreover, anterior subluxation of the lateral compartment (ASLC) and medial compartment (ASMC) in extension relative to the femoral condyles were measured on postoperative magnetic resonance imaging scans and compared between the groups. In addition, predictors of GRI were evaluated using multivariate logistic regression analysis and included body mass index, PTS, pivot-shift test, KT-1000 side-to-side difference, and concomitant meniscal tears.

RESULTS

PTS in the study group was significantly higher than that in control group (mean ± SD, 13.8°± 1.5° vs 9.5°± 1.8°; P < .05). In the study group (n = 26), patients with grade III (poor) graft signal intensity (n = 9) showed significantly higher PTS than those with grade II (moderate; n = 17) (16.4°± 1.7° vs 12.4°± 1.3°; P < .05). Moreover, the mean postoperative ASLC and ASMC in extension were significantly larger in the study group than the control group (ASLC, 4.1 ± 1.3 vs 0.8 ± 0.4 mm; ASMC, 4.3 ± 1.5 vs 0.9 ± 0.3 mm; P < .05). Furthermore, the abnormal degree of PTS (≥12°) was determined to be an independent risk factor associated with GRI after anatomic ACLR (odds ratio, 9.0 [95% CI, 3.7-30.2]; P < .001), whereas body mass index, grade of pivot-shift test, KT-1000 side-to-side difference, and concomitant meniscal tears were not.

CONCLUSION

Increased PTS (≥12°) was associated with greater risk of GRI after anatomic ACLR. This may provide additional information for counseling patients with greater risk of GRI.

Hamstring grafts for anterior cruciate ligament reconstruction show better magnetic resonance features when tibial insertion is preserved

PURPOSE

Comparing the MRI features of the grafts between a group of patients treated with an over-the-top anterior cruciate ligament reconstruction technique that preserves the hamstring attachment and a control group with a classical reconstruction technique.

METHODS

Patients were assigned to a standard reconstruction technique or an Over-the-top plus lateral plasty technique. All patients underwent preoperative, 4-months and 18-months MRI; together with a clinical evaluation with KOOS and KT1000 laxity assessment. MRI study involved different parameters: the "Graft" was evaluated with the continuity, Howell Grading system, presence of liquid and signal noise quotient. The "Tibial Tunnel" was evaluated with the signal noise quotient, presence of edema or liquid and tunnel widening. All points assigned to each parameter formed a composite score ranging from 0-10. Tunnel and graft positioning were evaluated.

RESULTS

At 18-month 20 MRIs (10 each group) were available, demographics were not significantly different between groups. The non-detached group showed significantly less liquid within the graft at 4-months (p = 0.008) and 18-months (p = 0.028), the tunnel was significantly smaller (p < 0.05) and less enlarged at both follow-ups (p < 0.05), signal noise quotient of the intra-tunnel graft was lower at 18-months (p < 0.05). The total score of the non-detached group saw a significant improvement at 4-months (p = 0.006) that remained stable at 18-months (n.s.).

CONCLUSIONS

Hamstring grafts, which tibial insertions were preserved, showed better MRI features at 4-and 18-months follow-up, especially in terms of liquid effusion, tunnel enlargement and signal noise quotient.

LEVEL OF EVIDENCE

IV.

Risk factors for postoperative graft laxity without re-injury after double-bundle anterior cruciate ligament reconstruction in recreational athletes

BACKGROUND

Although high activity is a risk factor for graft failure after anterior cruciate ligament (ACL) reconstruction, the risk factors for postoperative laxity after ACL reconstruction in recreational athletes are unknown.

METHODS

We enrolled 91 patients (40 males, 51 females; mean age 29.2 years; mean follow-up 4.3 years) who scored ≤ 6 on the Tegner activity scale, underwent double-bundle ACL reconstruction between 2010 and 2018, and did not experience re-injury. In the stable group (75 patients, <3.0 mm side-to-side difference (SSD) in anterior translation, grade 0 or 1 pivot shift 1 year after surgery) and unstable group (16 patients, ≥3.0 mm SSD, ≥grade 2 pivot shift), multivariate logistic regression analyses adjusted for factors showing P ≤ 0.3 on univariate analysis assessed risk factors for graft laxity. Lysholm score and graft intensity on MRI (Howell grade) were compared at final follow-up.

RESULTS

Mean SSD in anterior translation was 0.7 mm (stable group) and 3.3 mm (unstable group). Pivot shift grades were 0 (88%) and 1 (12%) in the stable group, and 0 (12.5%), 1 (50%), and 2 (37.5%) in the unstable group. Multivariate regression analyses showed that younger age and knee hyperextension were significant risk factors for graft laxity (P = 0.018 and 0.0016; cutoffs 18 years old and 8°, respectively). Lysholm scores in both groups were comparable, but graft intensity on MRI demonstrated significantly worse Howell grade in the unstable group (P = 0.002).

CONCLUSION

Younger age and knee hyperextension were risk factors for postoperative graft laxity without re-injury in recreational athletes.