Incidence of Proximal Adjacent Failure in Adult Lumbar Deformity Correction

Adjacent segmental failure has been recognized as a problem in fusion of adult lumbar deformity. There are some papers about distal fusion level and its distal adjacent segmental failure in adult lumbar deformity. However there are few written reports concerning proximal adjacent segmental failure according to the level of proximal fusion in adult lumbar deformity.

Purpose: To review 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.

Materials and 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 apex of adult lumbar deformity was below L1 on coronal and/or sagittal planes. The level of distal fusion was either L5 or S1 in all patients. Patients who had distal instrumentation failure were excluded. Average age was 62 years (range 38-75). All patients had standing anteroposterior and lateral radiographs of the whole spine, preoperatively, immediately postoperatively, and at the most recent follow-up. Thirty-five 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. Coronal and sagittal magnitude of the deformity, rate of correction, loss of correction, coronal and sagittal balance, proximal adjacent segmental problem and clinical complications were assessed.

Results: The preoperative coronal curve of 28±14º was corrected to 9±7º immediately after surgery and was measured 9±6º at the final follow-up. The lumbar lordosis was 14±18º before surgery; 27±11º after surgery; and 16±12º 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. The parameters of sagittal balance at the most recent follow-up were significantly more aggravated than those preoperatively in 10 patients: 5(36%) in Group 1; 5(36%) in Group 2; and none in Group 3. Proximal adjacent segmental problems that consisted with proximal disc degeneration with kyphosis, compression fracture above the fusion and screw failure at the proximal end of the fusion were observed in 16 patients: 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.