Imaging analysis of spiral fractures of distal third of the tibia fracture with occult posterior malleolar fracture / 中华放射学杂志

ABSTRACT

Objective To analyze the diagnostic value of MSCT and MRI in detecting the distal third of tibia shaft fracture complicated with occult posterior malleolar fracture.Methods One hundred and fifty-one patients with the distal third of tibia shaft spiral fracture underwent X-ray examination.For patients without posterior malleolar fracture on X-ray,MSCT and MR imaging were further performed.A binomial test was used to evaluate the significance of the differences between MSCT and MRI in the detection of posterior malleolar fractures and cortical involvement.Results A total of 126 (83.4％) in 151tibia shaft fracture were found to be associated with posterior malleolar fracture.Twenty-seven ( 21.4％ ) cases with posterior malleolar fracture were detected on X-ray.MSCT and MR examination were performed in 124 cases.Ninety-nine posterior malleolar occult fractures were detected on MRI,which included 81cases showed on MSCT.The sensitivity,specificity and accuracy of posterior malleolar occult fracture on MRI were 100％ (99/99),100％ (25/25) and 100％ ( 124/124),while they were 81.8％ (81/99),100％ (25/25)and 85.5％ (106/124) for MSCT respectively.The accuracy of posterior malleolar occult fracture on MRI was significant higher than MSCT ( Z =2.56,P =0.01).Seventy-eight cortical fractures were found on MSCT among 99 posterior malleolar occult fractures,while 51fractures were found on MRI.The sensitivity,specificity and accuracy of cortical fracture involvement were 100％ (78/78),100％ (21/21) and 100％ ( 99/99) for MSCT,while they were 65.4％ (51/78),100％ (21/21) and 72.7％ (72/99) for MRI respectively.The accuracy of cortical fracture involvement on MSCT was significant higher than MRI ( Z =4.02,P =0.00).Conclusions MRI has a higher accuracy than MSCT in detecting the distal third of tibia shaft fracture complicated with occult posterior malleolar fracture,while MSCT has a higher accuracy than MRI in detecting cortical fracture involvement.