title: Response to the Letter.
authors.affiliation: Department of Orthopedic Surgery, Beijing Key Laboratory of Arthritic and Rheumatic Diseases, China-Japan Friendship Hospital, National Health Commission of the People's Republic of China, Beijing, China.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: Gao
authors.affiliation: Department of Orthopedic Surgery, China-Japan Friendship clinical medical school, Peking University Health Science Center, Beijing, China.
authors.forename: Tianli
authors.initials: T
authors.lastname: Mao
authors.affiliation: Department of Orthopedic Surgery, Beijing Key Laboratory of Arthritic and Rheumatic Diseases, China-Japan Friendship Hospital, National Health Commission of the People's Republic of China, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Department of Orthopedic Surgery, Beijing Key Laboratory of Arthritic and Rheumatic Diseases, China-Japan Friendship Hospital, National Health Commission of the People's Republic of China, Beijing, China.
authors.forename: Zirong
authors.initials: Z
authors.lastname: Li