Objective To explore the correlation between different HLA‐B27 subgenotype and ankylosing spondylitis (AS ) . Methods The whole venous blood was collected from the outpatients and inpatients of the orthopedics ,acupuncture and rheuma‐tism departments and HLA‐B27 was qualitatively detected by using the gene analysis method .Among them ,380 cases of AS were HLA‐B27 positive ,and 50 cases of HLA‐B27 positive were selected as the healthy control group .Then the HLA‐B27 subgenotypes were detected by using the sequence specific primers PCR (PCR‐SSP) technology .Results Among 380 cases of AS ,217 cases (57 .1% ) of HLA‐AS B2704 subgenotype ,143 cases (37 .6% ) of HLA‐B2705 subgenotype ,11 cases (2 .9% ) of HLA‐B2707 sub‐genotype and 9 cases (2 .4% ) of HLA‐B2711 subgenotype were detected out ;among 50 cases of HLA‐B27 positive in the healthy control group ,23 cases (46 .0% ) of HLA‐B2706 subgenotype ,21 cases (42 .0% ) of HLA‐B2709 subgenotype ,4 cases (8 .0% ) of HLA B2704 subgenotype and 2 cases (4 .0% ) of HLA‐B2705 subgenotype were detected out ,the differences between the two groups were statistically significant (P=0 .002) .Conclusion The subgenotypes of HLA‐B27 among the AS patients in Baoji area are dominated by the genotype B2704 and B2705 ,which is strongly correlated with the occurrence of AS among Han population in Baoji area ;B2706 and B2709 are the protective subgenotypes in this area .

Objective: To evaluate the progress and influence factors of asymptomatic osteonecrosis of the femoral head(ONFH). Methods: MRI was performed on the contralateral hips of 174 patients with unilateral symptomatic ONFH who admitted at Department of Orthopaedics, the Second Affiliated Hospital of Xi′an Jiaotong University from January 2012 to December 2018. Eighty-three of 174 patients with unilateral ONFH were found suffering from contralateral ONFH(47.7%), of which 77 patients were followed up.There were 28 males and 49 females with age of 48.6 years (range: 21-73 years). The pathogenesis, ARCO classfication, areas and position of osteonecrosis were collected.Independent sample t test, χ² test, Fisher exact test, multivariate Logistic regression were used to analyze the potential influence factors. Results: Patients were followed up for 36.7 months. During the following up period, ARCO classification of 28 patients (36.4%) progressed.The progress of asymptomatic ONFH was not related to the gender, age and original ARCO classification, but related to the pathogenesis, position and area of osteonecrosis (all P<0.05). Conclusion The progress of asymptomatic osteonecrosis is related to the pathogenesis, position and area of osteonecrosis,but most of asymptomatic ONFH will not progress.