School of Public Health, North China University of Science and Technology, Bohai Road 21, Caofeidian Dis, Tangshan, 063210, People’s Republic of China

X.-l. Hou, Y.-y. Zhang, Y.-h. Yu, Y.-q. Tian & F.-m. Tian

The Second Hospital of Tangshan City, Tangshan, People’s Republic of China

J.-y. Liu

Kailuan General Hospital, Tangshan, People’s Republic of China

X.-h. Fan, N. Zhang & Z.-b. Guo

Gongren Hospital, Tangshan, People’s Republic of China

G.-l. Cao

Department of Orthopedic Surgery, Affiliated Hospital of North China University of Science and Technology, Jianshe South Road 73, Tangshan, 063000, People’s Republic of China

X.-x. Sun