Can the Interspinous Device, SPIRE TM , be an Alternative Fixation Modality in Posterior Lumbar Fusion Instead of Pedicle Screw?

AIM: Although conventional posterior lumbar interbody fusion (PLIF) using pedicle screws provides successful outcomes, pedicle screw related complications are sometimes noted. SPIRE? was invented as an interspinous fixation device (ISD) to replace pedicle screw. The aim of this study is to evaluate the clinical and radiological outcomes in patients who underwent unilateral PLIF using SPIRE? compared with a pedicle screw.

MATERIAL AND METHODS: All consecutive patients who show medically intractable lumbar degenerative disease with unilateral radiculopathy and mild instability were enrolled. Thirteen patients who underwent the PLIF using SPIRE? (ISD group), and age, gender, and index level matched patients who underwent the PLIF using pedicle screw (PS group) were recruited in a 1:1 ratio. Pain, Oswestry Disability Index (ODI), disc height, and slippage were evaluated.

RESULTS: Both PS and ISD groups revealed significant improvement and there was no significant difference between them (back pain, p=0.18; leg pain, p=0.51; ODI, p=0.82). Although the ISD group showed spondylolisthesis for the first 3 months after the surgery, there was no significant difference compared with the PS group (p=0.65). Disc height decreased in both the ISD group (10.8 mm?7.7 mm) and the PS group (12.8 mm?10.8 mm), and this difference had statistical significance (p < 0.01). In aspect of perioperative outcomes, the ISD group displayed better outcomes than the PS group (blood loss, p < 0.001; surgery time, p=0.017).

CONCLUSION: SPIRE? fixation for PLIF demonstrates comparable clinical outcomes with pedicle screw. It may provide weak fixation but it is acceptable. This technique may be an alternative for the patients with unilateral radiculopathy and mild instability.