An expandable crescent shaped TLIF cage to improve segmental lordosis: Safety, efficacy, and early clinical outcomes

2013

Summary

An FDA approved hydraulic expandable TLIF cage increased disc height and segmental lordosis in 266 patients undergoing lumbar arthrodesis and TLIF at 4 centers. There were no cage-related complications, and early clinical results showed improved VAS and ODI at 1 year. Radiographic analysis of the first 15 patients was compared to a matched cohort treated with fixed height cages. Patients treated with the expandable cages showed significantly improved lumbar lordosis and disc height compared to fixed height control cages.

Introduction

Expanding TLIF cages have the potential to improve interspace fit and fill, disc height, and segmental lordosis. This is the first report of clinical safety, efficacy, outcomes and radiographic improvement of an EC that is FDA approved for use in TLIF.

Methods

266 consecutive adults undergoing primary or revision arthrodesis were treated with TLIF using 356 crescent shaped, hydraulic expanding cages by 4 surgeons at 4 centers. Age: 58 years (19-86 years); Diagnoses split between deformity, degenerative, and spondylolisthesis. Levels treated: single – 191; 2 levels – 63; 3 levels – 14. Posterior fusions averaged 3.5 levels (2-9 levels). Technique: Expanding cages were placed front and center in the disc, expanded an average 3.4mm (0-6mm) to lift the anterior interspace, to act as a fulcrum to increase segmental lordosis. Backfill bone graft was used in all cases. Radiographs from the first 15 expandable cages were compared to matched controls with fixed cages for comparison of disc height and lordosis data.

Results

Both expandable cage and control cage increased anterior, mid, and posterior disc height (p<0.001) from pre-op, and increased segmental lordosis (expanding cage p<0.001; control p=0.019). Regional lordosis was not affected in either group. The expanding cage group improved segmental lordosis, anterior and mid disc height more than control (p=0.002/0.002/0.001); Expanding cage posterior disc height also improved more than control but was not significant (p=0.14). Clinically, early complications included infection - 2, neurologic deficit -0, pulmonary embolus – 1, loss of cage expansion height – 0. Revision surgery was required in 3 for unrelated adjacent level fractures in the thoracolumbar spine in deformity patients. For 38 patients with more than 12 months follow-up, improvement was noted in VAS: pre- 7.0, 1 year – 3.8; ODI scores improved: pre – 48.5 (P<0.05), 1 year – 28.9(P<0.05).

Conclusions

This study supports the safety, efficacy, and ability to improve segmental lordosis with a new hydraulic expandable TLIF cage. Early clinical outcomes suggest similar improvements with VAS and ODI as with other TLIF cages, with the advantage of increase segmental lordosis at the levels the cage was used.