Upper Thoracic versus Lower Thoracic as Site of Upper Instrumented Vertebrae for Long Fusion Surgery in Adult Spinal Deformity: A Meta-Analysis of Proximal Junctional Kyphosis.

OBJECTIVE: A meta-analysis was performed to compare incidence rates of radiographic and surgical proximal junctional kyphosis (PJK) between upper thoracic (UT) and lower thoracic (LT) vertebrae as site of upper instrumented vertebrae (UIV) endpoints for long fusion surgery in adult spinal deformity (ASD).

METHODS: MEDLINE, Embase, and Cochrane Library databases were searched for English-language articles that addressed UT versus LT fixation strategies. The division of the UT and LT groups was based on UIV. Two reviewers independently assessed the quality of the studies using the Newcastle-Ottawa Scale. Data on incidence rates of radiographic and surgical PJK were extracted from the included studies. RevMan 5.3 was used for data pooling and analysis.

RESULTS: Ten retrospective studies comprising 1230 patients were included. Pooled data on radiographic PJK were available in 9 studies comprising 1032 patients, and total radiographic PJK rate was 32.2%. Pooled data on surgical PJK were available in 6 studies comprising 732 patients, and total surgical PJK rate was 6.7%. Decreased radiographic PJK (95% confidence interval, 0.49-0.85; P = 0.002; I(2) = 48%) and surgical PJK (95% confidence interval, 0.18-0.76; P = 0.007; I(2) = 22%) were found in the UT group.

CONCLUSIONS: Radiographic PJK is a very common complication of long fusion surgery in adult spinal deformity with an incidence rate of 32.2%. Surgical PJK has an incidence rate of 6.7% and should be seriously considered. The pooled results indicate that choosing UT vertebrae as the site of UIV could decrease the incidence rates of radiographic and surgical PJK.