Comparative study of high-frequency ultrasonography and MRI in diagnosis of medial patellofemoral ligament injury after acute lateral traumatic patellar dislocation

Abstract

Objective To compare high-frequency ultrasonography and MRI in diagnosis of medial patellofemoral ligament (MPFL) injury after acute lateral traumatic patellar dislocation(LTPD).Methods According to surgical data of 35 patients with acute LTPD,the incidence and sites of MPFL injury were analyzed.Further,based on high frequency ultrasonography and MRI data,the sensitivity,specificity and accuracy of high-frequency ultrasonography and MRI in different MPFL injuries were analyzed and compared.Results Among 35 patients,there were 21 cases with complete MPFL tear and 14 cases with partial MPFL tear.Tear of MPFL at the femoral attachment in 19 cases,at the patellar attachment in 15 cases,and at the mid-substance in 1 case.The sensitivity,specificity,accuracy of high-frequency ultrasonography diagnosis were 78.6％,95.2％,88.6％ respectively on partial MPFL tear and 95.2％,78.6 ％,88.6 ％ respectively on complete MPFL tear.The sensitivity,specificity,accuracy of MRI diagnosis were 85.7％,90.5％,88.6％ respectively on partial MPFL tear and 90.5％,85.7％,88.6％ respectively on complete MPFL tear.There were no significant difference between high-frequency ultrasonography and MRI in diagnosis of partial and complete MPFL injury (x2 =0.243,0.267; P =0.622,0.599).Conclusions MPFL formoral attachment is most vulnerable to damage,followed by patellar attachment.High-frequency ultrasonography,as well as MRI,can be used clearly to diagnose MPFL injury and accurately classify the damage,and it is also an easy,reliable,rapid method,which can be applied routinely to diagnose MPFL injury after actue LTPD. Key words: Ultrasonography; Magnetic resonance imaging; Patellar dislocation; Medial patellofemoral ligament