169. To prevent PJK in Scheuermann's Kyphosis restore kyphosis to patient's PI value and choose proximal UIV

BACKGROUND CONTEXT Surgical correction of Scheuermann's kyphosis is challenging with high rates of proximal junctional kyphosis (PJK). Historically an anterior release and posterior fusion was thought to optimize correction. However, pedicle screws treatment through an all-posterior approach is the norm. No comparison study exists on PJK risks between anterior/posterior fusion and posterior fusion utilizing pedicle screws or posterior hybrid fixation in the treatment of SK. PURPOSE To determine if choosing a more proximal UIV and matching the kyphosis to pelvic incidence will lower the presence of PJK in SK patients. STUDY DESIGN/SETTING Retrospective, multi institution. PATIENT SAMPLE A total of 84 operative Scheurmann's kyphosis patients. OUTCOME MEASURES Kyphosis, PJK, kyphosis correction, pelvic incidence, kyphosis minus pelvic incidence METHODS SK patients operated with pedicle screw (PS), hybrid fixation (HF), and anterior/posterior fusions with hybrid fixation (AP). Sagittal parameters, % correction, UIV, kyphosis minus PI, Lordosis minus PI, PI-LL at early postop and minimum 2-year FU were measured. T1/T2 UIV were grouped together and compared to T3 and distal. RESULTS Median preop kyphosis was significantly higher in AP (p -10° at postop). When correcting kyphosis-PI to > -10° and UIV was chosen to be T1/T2, PJK developed in 30% of patients. When fusing to T1/T2 and kyphosis-PI -10° but UIV chosen at T3 or below, 66% of patients developed PJK. When fusing to T3 or below and failing to correct kyphosis-PI > -10°, 90% of patients developed PJK. CONCLUSIONS Incidence of PJK is higher in SK compared to that reported in AIS and similar irrespective of instrumentation or approach. Use of hooks provides benefits in the early postop but not at later follow up. Fusing short and overcorrection of kyphosis contributes towards PJK. Target kyphosis should be PI >-10° and UIV at T1/2. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.