Recurrent Proximal Junctional Kyphosis: Incidence, Risk Factors, Revision Rates and Outcomes at 2 year minimum follow up.

Abstract

STUDY DESIGN\nRetrospective Comparative Cohort Study OBJECTIVE.: Assess the incidence, risk factors and outcomes of recurrent PJK (R-PJK) in PJK revision patients.\n\n\nSUMMARY OF BACKGROUND DATA\nSeveral studies have identified the incidence and risk factors for PJK after primary surgery. However, few studies have reported on PJK recurrence after revision for PJK.\n\n\nMETHODS\nA multicenter database of patients who underwent PJK revision surgery with minimum 2 year follow up was analyzed. Demographic, operative and radiographic outcomes were compared in patients with R-PJK and patients without recurrence (N-PJK). Post-operative SRS-22r, SF-36 and ODI were compared. Pre-operative and most recent spinopelvic, cervical and cervicothoracic radiographic parameters were compared. Univariate and multivariate analyses were used to determine R-PJK risk factors. A predictive model was formulated based on our logistic regression analysis.\n\n\nRESULTS\nA total of 70 patients met the inclusion criteria with an average follow up of 21.8 months. The mean age was 66.3\u200a±\u200a9.4 and 80% of patients were female. Prior to revision, patients had a PJA angle of -31.7\u200a±\u200a15.9°. The rate of recurrent PJK was 44.3%. Logistic regression showed that pre-revision TPA (OR: 1.060 95%CI [1.002; 1.121] p\u200a=\u200a0.042) and pre-revision C2-T3 SVA (OR: 1.040 95%CI [1.007; 1.073] p\u200a=\u200a0.016) were independent predictors of r-PJK. Classification with these parameters yielded an accuracy of 72.7%, precision of 80.6% and recall of 73.5%. When examining correction, or change in alignment with revision surgery, we found that change in SVA (OR: 0.981 95%CI [0.968; 0.994] p\u200a=\u200a0.005) was the only predictor of r-PJK with accuracy of 66.7%, precision of 74.2% and recall of 69.7%.\n\n\nCONCLUSION\nPatients after PJK revision surgery had a recurrence rate of 44%. Logistic regression based on the pre-revision variables showed that pre-revision TPA and pre-revision C2-T3 SVA were independent predictors of r-PJK.\n\n\nLEVEL OF EVIDENCE\n4.