A new study published in Spine examines bone union after lumbar interbody fusion with titanium or PEEK cages to evaluate vertebral endplate cysts as a predictor of nonunion.
The researchers examined 117 patients who underwent treatment from March 2005 to July 2012. The patients underwent transforaminal LIF at 144 levels. There were 77 patients who had 93 levels treated with a titanium cage and 40 patients that had 51 levels treated with PEEK cages. The researchers evaluated the vertebral endplate cyst at three months as well as union status at one and two years after surgery.
The researchers found:
1. There was a 75.2 percent bone union rate for titanium cages and 74.5 percent union rate for PEEK cages one year after surgery. Two years after surgery there was an 82.8 percent union rate among the titanium group and 80.4 percent union rate in the PEEK group.
2. The researchers reported a positive cyst sign in 17.2 percent of the titanium patients and 13.7 percent of the PEEK patients.
3. For both groups, the nonunion rate was 100 percent with patients who had a positive cyst sign one year after surgery. Two years after surgery, 56.2 percent of the titanium group and 71.4 percent of the PEEK group reported nonunion.
4. For the titanium group, the sensitivity was 69.6 percent and specificity was 100 percent when calculated for the cyst sign and union status. The PEEK group reported sensitivity at 53.8 percent and specificity at 100 percent.
5. There weren't any significant differences between the two groups in:
• Bone union rate
• Positive cyst sign rate
• Nonunion rate with positive cyst sign
• Sensitivity
• Specificity