Objective:

To explore the spine-pelvis-hip alignments in degenerative spinal deformity (DSD) patients, and compare the outcomes in the procedure of long-fusion with posterior lumbar inter-body fusion (PLIF) or single-level three-column osteotomy (STO) at lower lumbar level (LLL, L₃ -S₁ ) and thoracolumbar levels (TLL, T₁₀ -L₂ ) for those patients.

Methods:

This is a retrospective study. Following institutional ethics approval, a total of 83 patients (Female, 67; Male, 16) with DSD underwent long-fusion with PLIF or STO surgery between March 2015 and December 2017 were reviewed. All of those patients were assigned into LLL and TLL groups. The average age at surgery was 65.2 years (SD, 8.1). Demographic (age, gender, BMI, and comorbidities), radiographs (both coronal and sagittal parameters) and health-related quality of life (HRQOL) assessments were documented. The radiographic parameters and HRQOL-related measurements at pre- and post-operation were compared with paired-samples t test, and those variables in the two groups were analyzed using an independent-sample t test. The relationships between pelvic incidence (PI) and other sagittal parameters were investigated with Pearson correlation analysis. The Pearson χ² or Fisher’s exact was carried out for comparison of gender, incidence of comorbidities and post-operative complications.

Results:

There were 53 and 30 patients in the LLL and TLL groups respectively. Those spino-pelvic radiographic parameters had significant improvements after surgeries (P < 0.001). The patients in the two group with different pre-operative thoracolumbar kyphosis (TLK, P = 0.003), PI (P = 0.02), and mismatch of PI minus lumbar lordosis (PI-LL, P = 0.01) had comparable post-operative radiographic parameters except PI (P = 0.04) and pelvic-femur angle (PFA, P = 0.02). Comparing the changes of those spine-pelvic-hip data during surgeries, the corrections of TLK in TLL group were significant larger (P = 0.004). Pearson correlation analysis showed that there were negative relationship between PI and TLK (r = -0.302, P = 0.005), positive relationship between PI and LL (r = 0.261, P = 0.016) at pre-operation. Those patients underwent the surgical procedure that long-segment instrumentation and fusion with STO would have higher incidence of complications involving longer operative timing (P = 0.018), more blood loss (P < 0.001), revision surgery (P = 0.008), and cerebrospinal fluid leakage (P = 0.001). All the HRQOL scores significantly improved at final follow-up (P < 0.001), with no difference of intra-group.

Conclusion:

Patients suffered de-novo scoliosis or hyper-kyphosis with low PI would be vulnerable to significant thoracolumbar degeneration, and have more changes of spine-pelvis-hip data after long-fusion surgery, however, those with high PI would be closed to significant lumbar degeneration. Although spine-pelvis-hip alignments in DSD patients can be restored effectively after long-fusion with PLIF or STO, the incidence of complications in patients underwent STO was significant higher than that in patients performed multi-level PLIF.