Middle patellar tendon to posterior cruciate ligament (PT–PCL) and normalized PT–PCL: New magnetic resonance indices for tibial tubercle position in patients with patellar instability

• Published in: The knee Vol. 25; no. 5; pp. 799 - 806
• Main Authors: Pozzi, Grazia, Al-Mnayyis, Asma'a, Almolla, Joan, Albano, Domenico, Messina, Carmelo, Merli, Ilaria, Mesquita, Romeu Duarte, Sconfienza, Luca Maria
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2018; Elsevier Limited
• Subjects: Adolescent; Adult; Age; Female; Humans; Image Processing, Computer-Assisted; Joint Instability - diagnostic imaging; Joint Instability - pathology; Knee; Magnetic Resonance Imaging; Male; Medical imaging; Middle Aged; NMR; Nuclear magnetic resonance; Patellar dislocation; Patellar instability; Patellar Ligament - diagnostic imaging; Patellar Ligament - pathology; Patellar tendon; Patellofemoral Joint; Patients; Posterior cruciate ligament; Posterior Cruciate Ligament - diagnostic imaging; Posterior Cruciate Ligament - pathology; Reproducibility of Results; ROC Curve; Tibia - diagnostic imaging; Tibia - pathology; Tibial tubercle; Work stations; Knee; Patellar instability; Tibial tubercle; Patellar dislocation; Posterior cruciate ligament; Patellar tendon
• ISSN: 0968-0160; 1873-5800
• DOI: 10.1016/j.knee.2018.05.018

To demonstrate whether the distance between the middle point of the patellar tendon and posterior cruciate ligament (PT–PCL) calculated on a single axial MR image could be an alternative measure to tibial tubercle–PCL (TT–PCL) distance for TT lateralization without the need of imaging processing. To show that normalization of PT–PCL (nPT-PCL) against the maximum diameter of the tibial plateau may help to identify patients with patellar instability (PI). MR scans of 30 patients (13 females, age 32 ± 13 years) with known PI and 60 patients (31 females, age 39 ± 19 years) with no history of PI were reviewed. Two operators calculated TT–PCL, and PT–PCL nPT-PCL. Intraclass correlation coefficient, Student's t-test, Receiver Operator Characteristic curves, Spearman's Rho and McNemar's test were used. Interobserver reproducibility was 0.894 for PT-PCL for TT-PCL (95% CI = 0.839–0.930) and 0.866 for TT-PCL (95% CI = 0.796–0.912). The PT–PCL was 23.5 ± 3.8 mm in patients and 20.0 ± 2.7 mm in controls (P < 0.001). The TT–PCL was 22.9 ± 3.9 mm in patients and 20.5 ± 2.7 mm in controls (P = 0.002). Correlation between the PT–PCL and TT–PCL was R = 0.838, P < 0.001. The PT–PCL had 66.6% (95% CI = 0.542–0.790) diagnostic yield. The nPT–PCL was significantly higher in patients (0.302 ± 0.03) than controls (0.271 ± 0.03; P < 0.001) with 73.9% (95% CI = 0.628–0.851) diagnostic yield. The PT–PCL correlated with TT–PCL, with 66.6% diagnostic yield. The nPT–PCL may represent an additional index, with 73.9% diagnostic yield.