ORTHOPEDIC AREA   

Medicina dello Sport 2013 June;66(2):253-64

Copyright © 2013 EDIZIONI MINERVA MEDICA

language: English, Italian

Knee instability signs: preliminary comparison between conventional and weight-bearing MRI in patients with complete anterior cruciate ligament tear

Villosio N. ^{1, 2}, Piccazzo R. ¹, Paparo F. ¹, Muda A. ¹, Garlaschi G. ¹ ✉

¹ IRCCS Azienda Ospedaliera Universitaria San Martino-IST, Istituto Nazionale per la Ricerca sul Cancro; ² Centro Provinciale-Medicina dello Sport Città di Cuneo C.O.N.I. - F.M.S.I

Aim: Knee instability is a relevant issue in patients with a complete anterior cruciate ligament (ACL) tear. Magnetic resonance imaging (MRI) is effective in the evaluation of instability signs in such patients. However, conventional MRI cannot provide an effective analysis of knee instability in standing position. The purpose of our study was to evaluate indirect signs of knee instability comparing conventional and weight-bearing MRI in patients with ACL tear.
Methods: Ten patients (7 males, 3 females; mean age 38.4±13.19 standard
deviation) with previous clinical and MRI diagnosis of ACL complete tear were evaluated performing two SE T1-weighted sequences (TR=890 ms, TE=24 ms; slice thickness=4.5 mm) both on sagittal and coronal planes. Scans were performed both in standard supine position and in weight-bearing position, using a low-field rotating MRI system (G-Scan, Esaote Biomedica, Genoa, Italy). For each patient, we evaluated signs of knee instability, i.e., verticalization of lateral collateral ligament on coronal images, posterior cruciate ligament
buckling, and anterior displacement of the tibia on sagittal images. For each patient, one radiologist with 15 years experience in MSK MRI graded each item as follows: 0=not present; 1=low-grade; 2=mild; 3=relevant, considering both conventional and weight-bearing examinations. K statistics were used.
Results: Lateral collateral ligament verticalization was graded as a median number of 1 (0.25-1.75 25th-75th percentile) in standard position and 2 (1.25-2) in weight bearing position, posterior cruciate ligament buckling was 0.5 (0-1) and 1 (1-1.75), and anterior displacement of the tibia was 1.5 (0.25-2) and 2.5 (1.25-3), respectively.
Conclusion: Weight-bearing MRI allowed for an increase detection of knee
instability signs in patients with complete ACL tear, compared to conventional MRI. Further investigations on a larger sample are needed to confirm our preliminary data. Reproducing the physiological condition of standing, weight-bearing MRI could be more effective in the detection of knee instability compared to standard MRI in patients with complete ACL rupture