Incidence of Proximal Adjacent Failure in Adult Lumbar Deformity Correction Based on Proximal Fusion Level

STUDY DESIGN: Retrospective study. PURPOSE: To review the results and proximal adjacent problems of long fusion (more than 4 levels) according to the level of proximal fusion (L2~T9) in adult lumbar deformity using pedicle screw fixation. OVERVIEW OF LITERATURE: There are few written reports concerning proximal adjacent segmental failure according to the level of proximal fusion in adult lumbar deformity. METHODS: The radiographs and clinical records of thirty-five patients (30 females, 5 males) of adult lumbar deformity with more than 2-year follow-up after surgery were analyzed. The average age was 62 years (range, 38~75). All patients were divided into three groups according to the level of proximal fusion: Group 1 (n=14) fusion up to L1 or L2; Group 2 (n=14) fusion up to T11 or T12; and Group 3 (n=7) fusion up to T9 or T10. RESULTS: The preoperative coronal curve of 28±14° was corrected to 9±7° immediately after surgery and 11±7° at the final follow-up. The preoperative local kyphosis of 24±12° was corrected to -1±10° immediately after surgery and 1±11° at the final follow-up. The lumbar lordosis was 14±18° before surgery; 27±11° after surgery; and 16±12° at the final follow- up. The parameters of coronal and sagittal balance were improved in all patients after surgery, except one patient in group 2 who showed coronal imbalance due to over-correction. Sagittal imbalance at the most recent follow-up was detected in 10 patients with significant difference between the groups; 5 (36%) in Group 1, 5 (36%) in Group 2, and none in Group 3. Proximal adjacent segmental problems that are consisted with proximal disc degeneration with kyphosis, compression fractures above the fusion and screw failure proximal to the end of the fusion were observed in 15 patients with significant difference between the groups; 7 (50%) in Group 1, 7 (50%) in Group 2, and 1 (14%) in Group 3. There was 1 superficial infection and 2 transient neurologies. CONCLUSIONS: Fusion up to throacolumbar junction (L2~T11) in surgical treatment of adult lumbar deformity had more proximal adjacent problems with poorer results. Fusion higher than T10 is recommended for adult lumbar deformity.