Standing and Sitting Lumbopelvic-Hip Alignments and Mobilities Predict Proximal Junction Kyphosis and Hip Osteoarthritis Following Spinopelvic Fusion Surgery.

BACKGROUND

This study evaluated spinal alignments and spine-hip mobilities between sitting and standing positions in the development of proximal junctional kyphosis (PJK) and hip osteoarthritis (HOA) in adult spinal deformity (ASD) surgery.

METHODS

This study included 90 patients (82 female, eight male; mean age=72.5 years) who underwent ASD surgery. Lumbo-pelvic parameters, including lumbar lordosis (LL), sacral slope (SS), and sacro-femoral angle (SFA), were measured in standing and sitting positions based on plain radiographs. The mobilities of each parameter were calculated between standing and sitting (ΔLL, ΔSS, ΔSFA). Proximal junctional angle (PJA) and Kellgren-Lawrence (KL) grade were compared between preoperative and postoperative values. The relationships between complications of ASD surgery and spinopelvic-hip alignments in standing and sitting positions were assessed.

RESULTS

The cut-off value of ΔLL for predicting PJK was 20 degrees and of ΔSFA for predicting HOA was 70 degrees, based on receiver operating curve parameters. We defined patients with a ΔLL of more than 20 degrees as spine users and a ΔSFA of more than 70 degrees as hip users. About 22 (24.4%) patients had PJK, and 16 (17.8%) patients developed progression of HOA. Being a spine user and the presence of PJA at pre-operation were statistically significant predictive factors for PJK. Progression of HOA was significantly related to being a hip user and the KL grade at pre-operation.

CONCLUSION

This study is the first to demonstrate that lumbar and hip mobilities before spinopelvic fixation in ASD patients may predict PJK and HOA postoperatively, respectively.