Etiological Study And Risk Factors Analysis On Osteonecrosis Of Femoral Head In Chinese Patients

ObjectiveOsteonecrosis of femoral head is a common disease with high morbidity. In recent years, there are great progressions concerning the diagnosis and treatment, thus brings benefit to the patient’s outcome. However, further understanding is still needed, especially reports about epidemiology of this disease in China, while in western countries there has been plenty of epidemiological reports. Therefore, exploring the constitution of the etiology and research on the clinical characteristics remains essential and valuable.MethodsData of this study was from the hospitalized patients of9large tertiary hospitals in China. This was so far one of the largest case investigation focusing on the etiology of osteonecrosis of femoral head. In this study I investigate and collected information using self-design questionnaire and medical records of the hospital. Age of the osteonecrosis of femoral head patients, gender, etiology,primary causes of the steroid-induced osteonecrosis of femoral head, correlation of the time when traumatic necrosis occurs and the removal of the internal fixation were carefully investigated and analyzed.Results1. A total of7224patients diagnosed with osteonecrosis of femoral head were primary included in this study. After confirming the medical records, only6352patients with complete medical records were finally included in the study.2. The mean±SD age of the patients is46.45±13.80(95%C.I.), in which45.44±12.83(95%C.I.) for men and48.84±15.59(95%C.I.) for women. Mean age of the women is3.4(95%C.I.2.67-4.14) years greater than men which indicates the early onset of the male patients comparing with the female. The results show that the age period of40to49is the most common age when osteonecrosis of femoral head occurs, this age period cover27%of the patients. 3. Male dominates in the osteonecrosis of femoral head patients with70.1%of male patients in all patients and29.9%of female patients.4. Among all the patient accepted total hip arthroplasty (THA) in hospital,35.9%of them were diagnosed as osteonecrosis of femoral head, more than one third.5. In all the osteonecrosis of femoral head patients,24.40%are steroid induced,30.49%are alcoholic,16.40%are traumatic and28.71%are idiopathic. The etiologic proportion among different hospital differs with region. There were obvious differences on etiology constituent ratio between different genders. Among male patients,40.4%of them are alcoholic osteonecrosis, while only5.9%of female patients are alcoholic osteonecrosis, among all the female patients,38.3%of them don’t have an obvious cause of osteonecrosis of the femoral head. Among all the1551steroid-induced osteonecrosis of femoral head patients,380patients’ has no records of primary disease. The most common cause among the rest1171patients is systemic lupus erythematosus which has217cases. According to the classification of all the primary causes,546patients has autoimmune disorder(46.63%), which is the most common etiology among steroid-induced osteonecrosis of femoral head.6. Among all the717patients who undergone surgeries for femoral neck bone fracture,273(38.1%) patients had the osteonecrosis of femoral head before the removal of the internal fixation,340(47.4%) patients after the removal. There are68(9.5%) patients who had the internal fixation for more than3years. There are also36(5.0) cases, which do not record the time of the removal surgery. The median time from the remove of internal fixation to the unset of osteonecrosis is1.56years; idiopathic osteonecrosis of femoral head is significantly related to the increased level of triglyceride (p<0.05).ConclusionThe most common age when osteonecrosis of femoral head occurs is between40to50years old. The mean age is about45years old, with male patients3-4years earlier than female patients. In the investigation of all the hospital, the number of the male patients is greater than the female, reaching the overall proportion of7:3in gender, while the gender proportion varies among different hospitals. Among all the etiologies of osteonecrosis of femoral head, trauma accounts for one sixth, steroid-induced necrosis accounts for one fourth. Systemic lupus erythematosus, SLE is the most common cause in the steroid-induced osteonecrosis of femoral head patients. Autoimmune disease is the primary cause of the steroid-induced osteonecrosis of femoral head, accounts for nearly half of the patients. Traumatic osteonecrosis of femoral head often occurs in patients underwent femoral neck bone fracture. Further research concerning the time of necrosis and the removal of the internal fixation is still needed.