Early Diagnosis Of Osteonecrosis Of The Femoral Head After Femoral Neck Fracture With Usage Of MRI

ObjectivesOsteonecrosis of the femoral head (ONFH) is a severe complication of femoral neck fracture. The purpose of this retrospective study was to evaluate the usage of MR I and syndrome differentiation on early diagnosis of osteonecrosis, which is critical for clinical decision.Patients and MethodsBetween Jan 1st,2006 and Apr 30th,2011,50 hips of 50 patients of our hospital who underwent surgical treatment for femoral neck fracture were included in this retrospective study. The clinical information was evaluated in different stages such as stage of less than three months after trauma, stage of 4-6 months, stage of 7-9 months, stage of 10-12 months, stage of 13-18 months, and stage of more than 18 months. Radiology outcome was evaluated with use of magnetic resonance imaging and radiograph. All cases with osteonecrosis were classified according to ARCO classification. The syndrome differentiation of traditional Chinese medicine divided into syndrome type of kidney & liver insufficiency and syndrome type of jin mai stasis.ResultsThe average duration of follow-up was 20.9 months. The MRI outcome about osteonecrosis was the same in different stage(100%). The sensitivity of diagnosis by MRI and radiograph in early stages was different. MRI was more sensitive in stages less than 12 months(P<0.05). in stage of 13-18 months and more than 19 months, there was no significant difference between MRI and radio graph (P>0.05).The ARCO stage progressed with time went by. ARCO stage I appeared between 2 and 17 months after trauma,7.636±4.293 months on average; ARCO stage II 3-26 months,15.875±7.736 months on average; ARCO stage III and IV 9-34 months, 17.600±11.675 on average.The patients with ONFH had different syndrome types. Group of less than 3 months had more type of jin mai stasis than group of 4-6 months (P<0.05). Group of more than 7 months had more type of jin mai stasis than group of 4-6 months (P<0.05). There was no significant difference between group less than 3 months and more than 7 months (P>0.05).ConclusionsThis study demonstrates that within one year postoperatively, MRI has an advantage over radiograph on diagnosis of osteonecrosis after femoral neck fracture. For the patients of femoral neck fracture, MRI can diagnose and may rule out osteonecrosis two months postoperatively. MRI can find the osteonecrosis eight months on average earlier than radiograph. Syndrome differentiation after femoral neck fracture may be helpful on early diagnosis of osteonecrosis.