Changes in the Cross-Sectional Profile of Treated Anterior Cruciate Ligament Within 2 Years After Surgery

Abstract

Background: The cross-sectional area (CSA) of the anterior cruciate ligament (ACL) and reconstructed graft has direct implications on its strength and knee function. Little is known regarding how the CSA changes along the ligament length and how those changes vary between treated and native ligaments over time. Hypothesis: It was hypothesized that (1) the CSA of reconstructed ACLs and restored ACLs via bridge-enhanced ACL restoration (BEAR) is heterogeneous along the length. (2) Differences in CSA between treated and native ACLs decrease over time. (3) CSA of the surgically treated ACLs is correlated significantly with body size (ie, height, weight, body mass index) and knee size (ie, bicondylar and notch width). Study Design: Cohort study; Level of evidence, 2. Methods: Magnetic resonance imaging scans of treated and contralateral knees of 98 patients (n = 33 ACL reconstruction, 65 BEAR) at 6, 12, and 24 months post-operation were used to measure the ligament CSA at 1% increments along the ACL length (tibial insertion, 0%; femoral insertion, 100%). Statistical parametric mapping was used to evaluate the differences in CSA between 6 and 24 months. Correlations between body and knee size and treated ligament CSA along its length were also assessed. Results: Hamstring autografts had larger CSAs than native ACLs at all time points ( P < .001), with region of difference decreasing from proximal 95% of length (6 months) to proximal 77% of length (24 months). Restored ACLs had larger CSAs than native ACLs at 6 and 12 months, with larger than native CSA only along a small midsubstance region at 24 months ( P < .001). Graft CSA was correlated significantly with weight (6 and 12 months), bicondylar width (all time points), and notch width (24 months). Restored ACL CSA was significantly correlated with bicondylar width (6 months) and notch width (6 and 12 months). Conclusion: Surgically treated ACLs remodel continuously within the first 2 years after surgery, leading to ligaments/grafts with heterogeneous CSAs along the length, similar to the native ACL. While reconstructed ACLs remained significantly larger, the restored ACL had a CSA profile comparable with that of the contralateral native ACL. In addition to size and morphology differences, there were fundamental differences in factors contributing to CSA profile between the ACL reconstruction and BEAR procedures. Registration: NCT 02664545 ( ClinicalTrials.gov identifier).

Can the ACL Cross-Sectional Area Be Predicted? Size Correlation and Proportion between the ACL Cross-Sectional Area and the Femoral Intercondylar Notch Area

“…Menghini et al reported that the reconstructed ACL was always larger than the native ACL at every time point within 2 years after ACL surgery. 18 As revealed in several studies, native ACL size is significantly correlated with knee size. 3,8,9,[11][12][13]17 Small knees have small ACL sizes, and large knees have large ACL sizes.…”

“…The range of previously reported ACL mid-substance cross-sectional sizes is 39.9 to 56.8mm. 2,3,5,8,10,18,19 However, in cadaveric studies the ACL is normally fixed with formalin, and the ACL mid-substance cross-sectional size tends to be underestimated. 8 Dienst et al reported that the ACL cross-sectional size in vivo was 54.4 to 56.8mm.…”

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how)

“…Recent work has also examined the impact of partial ACL injuries created via arthroscopy under multiple loading conditions 57 . Arthrotomy and arthroscopy can also be used for ACL repair and reconstruction procedures as reported previously in the literature 64,65 . Arthrotomy may be more appropriate for specific procedures, including those involving biologics in which a fluid environment may not be desired at the time of implantation 54 .…”

“…57 Arthrotomy and arthroscopy can also be used for ACL repair and reconstruction procedures as reported previously in the literature. 64,65 Arthrotomy may be more appropriate for specific procedures, including those involving biologics in which a fluid environment may not be desired at the time of implantation. 54 An arthroscopic approach allows similar techniques to modern ACL reconstruction in humans (Figure 5C).…”