The relationship between graft synovialization and graft revascularization after ACL reconstruction: Assessment using dynamic contrast enhanced-MRI and second-look arthroscopy

Abstract

Purpose: To assess graft vascularity via dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) at 1-year and 2-year postoperatively and to evaluate the relationship between the vascularity using DCE-MRI and the synovialization using second-look arthroscopy. Materials and methods: Fifty-four patients from prospective data included who underwent anterior cruciate ligament reconstruction (ACLR) and DCE-MRI. The graft was divided into proximal, middle, and distal zones; average of three zones was calculated. Signal/noise quotient (SNQ) was measured on proton-density image and normalized area under the curve (nAUC) was calculated from DCE-MRI. The results at 1-year (SNQ-1 and nAUC1) and 2-year (SNQ-2 and nAUC-2) postoperatively were compared between two time points. Forty-one patients underwent second-look arthroscopy were classified into three groups according to the synovialization: Excellent (n = 17), Fair (n = 16), and Poor (n = 8). The SNQs and nAUCs were compared between three groups. Results: Fifty-four and 23 patients underwent DCE-MRI at 1-year and 2-year, respectively. A significant decrease was observed from nAUC(average)-1 to nAUC(average)-2 (95 % confidential interval, 0.4-2.3; P = .007). Both SNQ(average-1) and SNQ(average)(-2) were significantly lower in the excellent than in the poor (SNQ(average-1), P < .001; SNQ(average)-(2), P = .003). Both SNQ(average-1) and SNQ(average)(-2) were significantly lower in the fair than in the poor (SNQ(average-1), P=.032; SNQ(average-2), P = .012). Both nAUC(average-1) and nAUC(average-2) were significantly higher in the excellent than in the poor (nAUC(average-1), P < .001; nAUC(average-2), P = .010). The nAUC(average-1 )was significantly higher in the excellent than the fair (nAUC(average-1), P < .001). Conclusion: Well-synovialized grafts showed significantly lower SNQs and significantly higher nAUCs than did poor-synovialized grafts based on the second-look arthroscopic findings. We can indirectly infer from this result that well-synovialized grafts may have better biomechanical properties.