35. The clinical benefit of addressing the malalignment in revision surgery for proximal junctional kyphosis following ASD surgery

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) is a common cause of revision surgery for ASD patients. Surgeons may elect to perform a proximal extension of the fusion, or, also correct the source of the lumbo-pelvic mismatch. The goal was to determine if there is clinical benefit in addressing the root cause of PJK. PURPOSE To investigate the clinical benefit of addressing malalignment in revision surgery for PJK. STUDY DESIGN/SETTING Retrospective cohort study of a prospective multicenter ASD database. PATIENT SAMPLE A total of 137 ASD patients. OUTCOME MEASURES Complications, HRQLs (SF-36, ODI, SRS-22). METHODS ASD patients undergoing revision surgery for PJK with fusion to ilium and an upper instrumented vertebrae at C5 or below. Correction in sagittal alignment was identified by patients who went from under- or overcorrected prerevision in PI-LL, SVA or PT to an ideal matched alignment in the Schwab age-adjusted criteria. Improvement in PI-LL was defined by a decrease in SRS-Schwab deformity category. RESULTS A total of 137 ASD patients undergoing revision surgery for PJK. 12.6% (19) were anterior and 84% (127) were posterior approaches. Operative time was 309±137, EBL 1327±1519, 75% had osteotomies and 33% had 3-column osteotomies. Average number of levels fused was 11±5. A total of 46% of patients undergoing revision surgery for PJK were corrected in sagittal alignment as well. Specifically, 21% of patient were corrected in PT, 20% corrected in SVA, and 14% corrected in PILL. Patients corrected in SVA vs fusion extension only had similar rates of PJK by 2 years, with a lower ODI (p 0.05). Patients under corrected in SVA initially and overcorrected post-operatively had a greater development of recurrent PJK (86% vs 63%, p=.066). Patients undercorrected in PILL preoperatively and overcorrected postoperatively had a greater development of recurrent PJK (70% vs 56%, p=.184). Patients who were under/overcorrected in PILL and matched postoperatively, due to surgical realignment at revision, trended towards a lower NSR 2Y back pain (2.4 vs 3.9, p=.20). In a cohort of patients with 2Y follow-up (n=52), patients who improved in PI-LL had lower rates of PJF (8% vs 17%, p=.4) and reoperation (21% vs 32%, p= .4) than patients who only had an extension of fusion. Patient who were under/overcorrected and matched in T1PA showed lower rates of post-operative PJK (44% vs 55%, p=.6), 2Y PJK (67% vs 74%, p=.6) and proximal junctional failure (11% vs 15%, p=.7). CONCLUSIONS In patients undergoing revision surgery for PJK, those who maintained poor sagittal alignment showed worse clinical outcomes compared with patients who had their abnormal lumbo-pelvic mismatch corrected as well. While limited by sample size, these findings suggest addressing the root cause of surgical failure in addition to proximal extension of the fusion may be beneficial. Future studies with a larger cohort should be done to further investigate. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.