Alexandre Hardy1, Shahnaz Klouche2, Pierre Szarzynski1, Etienne Charpentier1, Jean Sebastien Beranger1, Thomas Bauer1,3, Benoit Rousselin1, Olivia Judet1, Philippe Hardy1,3. 1. Hôpital Ambroise Paré, Service de Chirurgie Orthopédique et Traumatologie, Hôpitaux Universitaires Paris Ile de France Ouest, Assistance Publique-Hôpitaux de Paris, 9, avenue Charles de Gaulle, 92100, Boulogne-Billancourt, France. 2. Hôpital Ambroise Paré, Service de Chirurgie Orthopédique et Traumatologie, Hôpitaux Universitaires Paris Ile de France Ouest, Assistance Publique-Hôpitaux de Paris, 9, avenue Charles de Gaulle, 92100, Boulogne-Billancourt, France. klouche_shahnaz@yahoo.fr. 3. Université de Versailles Saint-Quentin-en-Yvelines, UFR des Sciences de la Santé, 78180, Montigny-le-Bretonneux, France.
Abstract
PURPOSE: To identify and quantify passive anterior tibial subluxation on MRI using a standardized measurement protocol and determine the diagnostic threshold of subluxation for complete anterior cruciate ligament tears. METHODS: A retrospective case-control study was performed. Patients who underwent surgery for a complete isolated ACL tear between 2009 and 2015 were matched for age and gender to controls with an intact ligament on knee MRI. All subjects underwent 1.5 T closed field MR imaging with the same protocol. Measurements were performed on axial sequences to evaluate translation of the medial and lateral condyles compared to the tibial plateau. Each compartment was measured between the vertical tangent to the posterior femoral condyles and the most posterior part of the tibial plateau. The main criterion was global passive subluxation measurements on MRI, corresponding to mean medial and lateral compartment subluxation. The reproducibility and diagnostic value of passive subluxation were calculated. RESULTS: Sixty (30/30) subjects were included, mean age 27.1 ± 1.7 years, 20 women and 40 men. Patients had a significantly higher global passive subluxation than controls (3.3 ± 0.6 mm vs 0.6 ± 0.2 mm, respectively p < 0.00001). Reproducibility was excellent and the diagnostic value of passive subluxation for a complete ACL tear was fair. A passive subluxation threshold of 3.5 mm had a sensitivity of 55.2%, a specificity of 100% and 77.6% of well-classified subjects. CONCLUSION: The calculated cutoff value for global passive subluxation to identify patients with a complete ACL tear was 3.5 mm, with excellent specificity and a high positive likelihood ratio. Suboptimal clinical results following ACL reconstruction could be partially due to failure to restore an anatomical femorotibial relationship. LEVEL OF EVIDENCE: III.
PURPOSE: To identify and quantify passive anterior tibial subluxation on MRI using a standardized measurement protocol and determine the diagnostic threshold of subluxation for complete anterior cruciate ligament tears. METHODS: A retrospective case-control study was performed. Patients who underwent surgery for a complete isolated ACL tear between 2009 and 2015 were matched for age and gender to controls with an intact ligament on knee MRI. All subjects underwent 1.5 T closed field MR imaging with the same protocol. Measurements were performed on axial sequences to evaluate translation of the medial and lateral condyles compared to the tibial plateau. Each compartment was measured between the vertical tangent to the posterior femoral condyles and the most posterior part of the tibial plateau. The main criterion was global passive subluxation measurements on MRI, corresponding to mean medial and lateral compartment subluxation. The reproducibility and diagnostic value of passive subluxation were calculated. RESULTS: Sixty (30/30) subjects were included, mean age 27.1 ± 1.7 years, 20 women and 40 men. Patients had a significantly higher global passive subluxation than controls (3.3 ± 0.6 mm vs 0.6 ± 0.2 mm, respectively p < 0.00001). Reproducibility was excellent and the diagnostic value of passive subluxation for a complete ACL tear was fair. A passive subluxation threshold of 3.5 mm had a sensitivity of 55.2%, a specificity of 100% and 77.6% of well-classified subjects. CONCLUSION: The calculated cutoff value for global passive subluxation to identify patients with a complete ACL tear was 3.5 mm, with excellent specificity and a high positive likelihood ratio. Suboptimal clinical results following ACL reconstruction could be partially due to failure to restore an anatomical femorotibial relationship. LEVEL OF EVIDENCE: III.