Proximal Kyphosis, “Topping Off Syndrome”, and Retrolisthesis Secondary to Multilevel Lumbar Fusion in the Elderly Patients

Summary: The relationship between sagittal configuration of the proximal segments and the number of lumbar fusion segments in patients older than 60 years was studied. The fusion rate was 88%. Fusion of L1-L5 or S1 caused more kyphotic changes and "topping off syndrome"; Fusion of L2-L5 or S1 had less severe adjacent degeneration; Retrolisthesis is a significant problem in fusion L3-L5 or S1. The least adjacent level degenerative changes were seen in L4-S1 fusion.

Introduction: The aim of this study was to radiographically analyze the relationship between abnormal sagittal plane configuration of the proximal segments and the number of lumbar fusion segments in patients older than 60 years age.

Methods: Since January 1997, there were 52 consecutive patients with an average age of 70 years who have undergone multilevel lumbar decompression and posterolateral fusion with pedicle screw-rod instrumentation, and have reached a minimum 2-year follow up. The preoperative diagnoses are degenerative lumbar disorders. Postoperative radiographs of lumbar fusion were classified into group A (L1-L5 or S1), group B (L2-L5 or S1), group C (L3-L5 or S1) and group D (L4-S1).

Results: Solid fusion was seen in 46 (88%) patients. There were 10 patients in group A, and 2 (20%) had vertebral compression fractures in the most cranial vertebrae and 4 (40%) focal kyphosis. Of 15 patients in group B, 1 (6%) had compression fracture, 5 (33%) retrolisthesis, and 2 (13%) focal kyphosis. Of 18 patients in group C, retrolisthesis was seen in 7 (39%) patients. Group D had 9 patients with only 1 patient having retrolisthesis and 2 having disc height loss.

Discussion: The fusion rate of 88% in this study is comparable with those of the younger patients reported in literature. It appears that lumbar fusion up to L1 cause more kyphotic changes and "topping off syndrome". Fusion from L2 down to L5 or S1 seems having less severe adjacent degeneration. Retrolisthesis is a significant problem in fusion L3-L5 or S1. The least adjacent level degenerative changes were seen in L4-S1 fusion.

Conclusion: Mismatch in elastic modulus between the instrumented segments and adjacent native bone is poorly tolerated in the elderly with osteoporotic spine. Selected limited instrumentation avoiding kyphotic segments or extending the fusion above the thoracolumbar junction may be the option.