My name is Julia Retske and I'm going to be presenting our project looking at the impact of LET on signal intensity of the ACL grafts on MRI. My co-authors and I have no disclosures. Since 2015, Dr. Green and Dr. Kordasko have been adding a modified LAMARE lateral extra-articular tenodesis to primary ACL reconstruction in high-risk adolescents. They have demonstrated excellent clinical outcomes, low failure rate, and high return to sport using this technique. Several recent studies have described the use of MRI to evaluate the ACL graft signal intensity throughout the postoperative course. One recent study out of China found that ACL graft signal hyperintensity at two years postoperative was associated with increased risk of graft rupture. Therefore, ACL graft signal intensity may act as a surrogate for graft maturity. At our institution, routine postoperative protocol calls for MRI at 6 months, 1 year, and 2 years postoperative in skeletally immature patients for the purposes of FICL surveillance. So given this unique access to MRI scans in patients who are otherwise completely asymptomatic, two years ago our group looked at ACL graft signal intensity at 6 months and 1 year postoperatively in patients undergoing ACL reconstruction with either quadriceps or hamstring tendon autograft and found that the quadriceps tendon autograft had lower signal intensity ratios at 1 year postoperative compared to the hamstring grafts. The purpose of our study was to evaluate ACL graft maturity using signal intensity ratios on MRI at 6 months, 1 year, and 2 years postoperative for patients undergoing ACL reconstruction with quadriceps tendon autograft either with or without concomitant LET. We hypothesized that the addition of LET to an ACL reconstruction would be associated with lower average signal intensity ratio values compared to patients without LET. We included patients under the age of 18 with open distal femoral and proximal tibial FICEs who are undergoing ACL reconstruction with a quad autograft with or without LET and excluded patients with hamstring autografts, those undergoing revision ACL reconstruction if MRI were ordered due to a new injury or if no 2-year postoperative MRI were available. The signal intensity ratio was calculated as the average of three regions of interest along the ACL graft divided by the PCL signal at its insertion on the tibia. Of the 73 patients that we identified, 29 were included with an average age of 13 and average follow-up of just over 3 years. There were a greater proportion of females and patients undergoing transficial ACL reconstruction in the ACL with LET group compared to the ACL only group. Notably there are no differences with regard to BMI, age, concomitant procedures performed, timed MRI or follow-up time between these two groups. We found that signal intensity ratio values were lower at 2-years postoperative in the ACL with LET group compared to the ACL only group. Although the SIR values tended to be lower at 6 months and 1-year postoperative in the ACL with LET group, this finding was not significant. These are a couple of representative images of the ACL grafts used for the measurements. As you can see on the left, in the patient with the ACL and LET, the ACL graft itself is darker, closer to that of the PCL compared to the patient on the right who had an ACL only. So given that there were differences between the two groups, particularly with sex and surgical technique which may serve as confounding variables, we performed a multivariate linear regression analysis using the significant variables from our univariate analysis including the presence or absence of LET, surgical technique and sex as inputs to the model. And after controlling for both sex and surgical technique, we still found that LET was associated with lower SIR values at 2-years postoperative. So in conclusion, the addition of LET to an ACL reconstruction with quadriceps tendon autograft is associated with improved graft signal on MRI 2-years postoperatively compared to ACL reconstruction alone. We speculate that this may be due to protective effect of the LET on the ACL graft. Thank you.

Julia Retske

lateral extra-articular tenodesis

ACL grafts

MRI

ACL reconstruction