Maintenance of intraoperative correction with multi-rod constructs in adult long construct spine fusion surgery

Objective

The purpose of this study was to evaluate the risk factors for loss of intraoperative correction, as measured by lumbar lordosis (LL), with an emphasis on rod characteristics.

Methods

A retrospective study identified patients at least 50 years of age who underwent instrumented fusion with an upper instrumented vertebrae (UIV) in the upper thoracic spine (T1-T6) or thoracolumbar junction (T10-L2) to the pelvis. Inclusion criteria included intraoperative x-rays that allowed for LL measurement, postop standing x-rays, and a minimum follow up of 24 months with the original rods still in place.

Results

One hundred and twelve patients (69 % women) were included with an average (SD) follow up of 58 months (29). Twenty-two patients (20 %) had a 10° change in LL from intraoperative to postoperative, and risk factors included a two-rod compared to multi rod (>2) construct (23 % vs 0 %, p = 0.04), male sex (34 % vs 13 %, p = 0.02), UIV near the thoracolumbar junction (28 % vs 8 %, p = 0.02), and higher L4-S1 intraoperative lordosis (41° vs 36°, p = 0.024). Forty-one patients (37 %) had a 10° change in LL at two years, and risk factors included male sex (60 % vs 26 %, p < 0.001) and a UIV near the thoracolumbar junction (48 % vs 21 %, p = 0.003).

Conclusions

Risk factors for loss of LL between intraoperative and postoperative alignment include two-rod constructs, male sex, lower UIV, and greater intraoperative LL. Multi-rod (3 +) constructs may be a modifiable surgical technique that better maintains the spinal alignment that was achieved in the operating room.