Quantitative MRI Biomarkers to Predict Risk of Reinjury Within 2 Years After Bridge-Enhanced ACL Restoration

Abstract

Background: Quantitative magnetic resonance imaging (qMRI) methods were developed to establish the integrity of healing anterior cruciate ligaments (ACLs) and grafts. Whether qMRI variables predict risk of reinjury is unknown. Purpose: To determine if qMRI measures at 6 to 9 months after bridge-enhanced ACL restoration (BEAR) can predict the risk of revision surgery within 2 years of the index procedure. Study Design: Cohort study; Level of evidence, 2. Methods: Originally, 124 patients underwent ACL restoration as part of the BEAR I, BEAR II, and BEAR III prospective trials and had consented to undergo an MRI of the surgical knee 6 to 9 months after surgery. Only 1 participant was lost to follow-up, and 4 did not undergo MRI, leaving a total of 119 patients for this study. qMRI techniques were used to determine the mean cross-sectional area; normalized signal intensity; and a qMRI-based predicted failure load, which was calculated using a prespecified equation based on cross-sectional area and normalized signal intensity. Patient-reported outcomes (International Knee Documentation Committee subjective score), clinical measures (hamstring strength, quadriceps strength, and side-to-side knee laxity), and functional outcomes (single-leg hop) were also measured at 6 to 9 months after surgery. Univariate and multivariable analyses were performed to determine the odds ratios (ORs) for revision surgery based on the qMRI and non-imaging variables. Patient age and medial posterior tibial slope values were included as covariates. Results: In total, 119 patients (97%), with a median age of 17.6 years, underwent MRI between 6 and 9 months postoperatively. Sixteen of 119 patients (13%) required revision ACL surgery. In univariate analyses, higher International Knee Documentation Committee subjective score at 6 to 9 months postoperatively (OR = 1.66 per 10-point increase; P = .035) and lower qMRI-based predicted failure load (OR = 0.66 per 100-N increase; P = .014) were associated with increased risk of revision surgery. In the multivariable model, when adjusted for age and posterior tibial slope, the qMRI-based predicted failure load was the only significant predictor of revision surgery (OR = 0.71 per 100 N; P = .044). Conclusion: Quantitative MRI-based predicted failure load of the healing ACL was a significant predictor of the risk of revision within 2 years after BEAR surgery. The current findings highlight the potential utility of early qMRI in the postoperative management of patients undergoing the BEAR procedure.

Anterior Cruciate Ligament Return to Play: Where Are We Now?

“…Predicted load to failure, as calculated from MRI evaluation of patients, can determine predicted revision risk within two years of surgery. 42 This was also true when machine learning was applied to MRIs of patients who were status post ACLR, with lower revision rates in patients with higher estimated load to failure. 44 Newer MRI sequences are allowing more standardized evaluation of the maturity of ACL grafts.…”

“…Ultimately, the predicted failure load, as calculated from a previously determined porcine model, was the only significant predictor of revision risk within 2 years of surgery for this cohort. 42 This was calculated directly from the MRI evaluation of these patients, making this an intriguing technology for the evaluation of graft healing and overall maturation.…”

“…Imaging modalities have garnered increased attention of late. A cohort study by Barnes et al, 42 sought to quantify magnetic resonance imaging (MRI) findings in patients who had undergone bridge-enhanced ACL restoration (BEAR) to determine whether these correlated with revision surgery incidence. The study included 119 patents and MRI was analyzed for cross-sectional area, normalized signal intensity, and a quantitative MRI (qMRI)-predicted failure load.…”

Comprehensive evaluation of magnetic resonance imaging sequences for signal intensity based assessment of anterior cruciate ligament healing following surgical treatment

“…We additionally evaluated the required sample size necessary for future studies to detect longitudinal changes in SI, depending on the sequence used. CISS is a gradient‐echo sequence available on common MRI platforms (Siemens: CISS, GE: FIECTA‐C, Philipps: BFFE‐XD) which offers high spatial resolution and has shown promises in quantifying the healing of the surgically treated ACLs/grafts and outcomes 14,15,31–33 . We hypothesized that CISS is a better sequence for capturing longitudinal remodeling in the surgically treated ACL compared to the common clinical sequences by capturing postoperative changes in SI texture parameters related to healing ligament maturation, and by estimating the required sample size to detect longitudinal changes in SI calculated from CISS versus other sequences.…”