Department of Biochemistry,Faculty of Medicine,Chulalongkorn University;
King Chulalongkorn Memorial Hospital,Thai Red Cross Society;
Vinai Parkpian Orthopaedic Research Center,Department of Orthopaedics,Faculty of Medicine,Chulalongkorn University;
Hypovitaminosis; D; Outcome; Prevalence; Spine; surgery; Vitamin; D;