P97. The varus knee phenomenon in spine deformity patients

Abstract

BACKGROUND CONTEXT There is a paucity in the literature describing coronal compensatory mechanisms of the lower extremities in spine deformity patients. This study aims to report the prevalence of the varus knee phenomenon in spine deformity patients and assess the changes in the lower extremity mechanical axis after deformity correction surgery. PURPOSE Spine deformity patients are predisposed to having varus knees that will self-correct postoperatively with restoration of global spine alignment. STUDY DESIGN/SETTING Retrospective cohort. PATIENT SAMPLE A total of 361 patients undergoing spinal deformity surgery between July 2015 and July 2018. OUTCOME MEASURES The prevalence of varus knees on pre- and postoperative standing films was adjusted for patient demographics and diagnosis. METHODS A single center radiographic review of all patients undergoing spinal deformity surgery between July 2015 and July 2018 were included. All patients had full-length standing spine pre- and post-operative films with an identifiable lower extremity mechanical axis. The prevalence of varus knees on pre- and postoperative standing films was adjusted for patient demographics and diagnosis. RESULTS A total of 361 patients met the inclusion criteria. There was 268 adult (>18 years) and 93 pediatric ( CONCLUSIONS The adult spine deformity patients, particularly those with ADS, are predisposed to having preoperative varus knee posture compared to the pediatric patients. Spine deformity correction surgery corrected the lower extremity mechanical malalignment in more than half of the adult patients with preoperative varus knee postures and all of the pediatric patients with varus knees. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.