Abstract
BackgroundRevision anterior cruciate ligament (ACL) reconstruction requires a precise evaluation of previous tunnel locations and diameters. Enlargement of the tunnels, despite not usually affecting primary reconstruction outcomes, plays an important role in revision ACL management. Three dimensional (3D) computed tomography (CT) models are reported to be the most accurate method for identifying the tunnel position and possible conflicts with a revision tunnel placement. However, the ability of 3D CT to measure the tunnel size is still not proven. The goal of this study was to evaluate the ability of measuring the size of the bone tunnels in ACL reconstructed knees with 3D CT compared to the traditional two dimensional (2D) CT method.MethodsTwenty-four patients had CT scans performed immediately following ACL reconstruction surgery. Their femoral tunnels size were measured by a standard 2D CT measurement and then compared with three novel 3D CT measuring methods: the best transverse section method, the best fit cylinder method and the wall thickness method. The drill size used during surgery was used as a control measure for the tunnel width. Intra-class correlation coefficients were obtained.ResultsThe intra-class correlation coefficient and respective 95% confidence interval range (ICC [95%CI]) for the three methods compared with the drill sizes were 0.899 [0.811-0.947] for the best transverse section method, 0.745 [0.553-0.862] for the best fit cylinder method, −0.004 [−0.081 to −0.12] for the wall thickness method and 0.922 [0.713-0.97] for the 2D CT method. The mean differences compared to the drill size were 0.02 mm for the best fit transverse section method, 0.01 mm for the best fit cylinder diameter method, 3.34 mm for the wall thickness method and 0.29 mm for the 2D CT method. The intra-rater agreement (ICC [95%CI]) was excellent for the best transverse section method 0.999 [0.998-0.999] and the 2D CT method 0.969 [0.941-0.984].ConclusionsThe 3D best transverse section method presented a high correlation to the drill sizes and high intra-rater agreement, and was the best method for ACL tunnel evaluation in a 3D CT based model.
Highlights
Revision anterior cruciate ligament (ACL) reconstruction requires a precise evaluation of previous tunnel locations and diameters
Patients were excluded from the study if they presented with ACL revision reconstruction, ACL lesion of the contralateral knee, concomitant PCL, lateral or medial instability at the time of the surgery, established osteoarthritis with Kellgren-Lawrence classification grades 3 or 4 or hamstring grafts unable to have a minimum diameter of 5 mm for each bundle
Tunnel size The drill size range used for the ACL reconstructions in this study was from 5.0 to 9.0 mm and the difference between the average of the drill sizes and the measurements means and respective standard deviation were 0.29 ± 0.4 mm for the Two dimensional (2D) computed tomography (CT) method, 0.02 ± 0.6 mm for the best fit transverse section method, 0.01 ± 0.8 mm for the best fit cylinder diameter method and 3.34 ± 2.1 mm for the wall thickness method (Figure 7)
Summary
Revision anterior cruciate ligament (ACL) reconstruction requires a precise evaluation of previous tunnel locations and diameters. Three dimensional (3D) computed tomography (CT) models are reported to be the most accurate method for identifying the tunnel position and possible conflicts with a revision tunnel placement. The goal of this study was to evaluate the ability of measuring the size of the bone tunnels in ACL reconstructed knees with 3D CT compared to the traditional two dimensional (2D) CT method. No Different methods for measuring tunnel width have been described in the literature using two dimensional (2D) radiography, computed tomography (CT) and magnetic resonance imaging (MRI) [12,13,14,15,16]. Interobserver and intraobserver reliability have been reported to be inconsistent [12,17]
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