516 - A Modular Large Footprint Interbody in Adult Spinal Deformity Patients...

Oral Posters: Adult Spinal Deformity

Presented by: W. Lavelle - View Audio/Video Presentation (Members Only)

Author(s):

W. Lavelle(1), R. Tallarico(1)

(1) SUNY Upstate Medical University, Department of Orthopedic Surgery, Syracuse, NY, United States

Abstract

Introduction: Surgery for patients with adult spinal deformity (ASD) has become more common with the aging population. This is driving demand for surgical solutions that provide relief from the pain and disability associated with ASD. Improved implants and surgical techniques along with a better understanding of spinal biomechanics have helped improve the outcomes of long construct surgeries in patients with ASD. In spite of these improvements, surgery for ASD still carries a high risk of reoperation. In a recent report from the International Spine Study Group the reoperation rate was still over 28% at two years. Common causes of reoperation are infection, subsidence, pseudarthrosis, instrumentation breakage and adjacent segment disease. We hypothesized that a large footprint interbody inserted from a posterior approach at the base (L4-5, L5-S1) of a long construct ASD surgery would provide optimal support and stability and reduce the occurrence of some of the common causes of reoperation.

Methods: We present one year follow-up data on the initial 15 patients in a prospective, multicenter observational study to evaluate if the improved stability and end plate support of a large footprint interbody device will provide better fusion results and lower reoperation rates when compared with historical control patients from previously published series. All patients received a modular PEEK interbody implant with approximately 500 sq mm of surface area at L4-5 and/or L5-S1. Patients had a long construct fusion with an average of three more levels above the L4-5 level. Data on Visual Analog Scale (VAS) leg and back pain, Oswestry Disability Index (ODI), Short Form- 36 (SF-36), and the Zurich claudication questionnaire were collected by an onsite clinical coordinator and transmitted electronically to a central data repository. Lumbar spine CT scans were obtained at 12 and 24 months and read by and outside spine radiologist.

Results: The patient population consisted of 7 males and 8 females, age range 40 to 76, with an average body mass index (BMI) of 31.3. Six patients had BMIs over 33. At one year, VAS leg pain improved by an average of 49%, and VAS back pain improved by an average of 42%. The ODI, and the Zurich Claudication scale both improved about 30%. Two patients required reoperation; one for a loose screw cap and the other for a broken rod at L3-4 above the study implant level. No other SAE were observed. The reoperation rate was 13.3% in this small series. Without the loose screw cap the reoperation rate was 6.6% at one year. No patients showed evidence of infection. Bridging bone was seen forming at all study interbody levels. No evidence of implant loosening was seen other than noted above. Levels with the modular interbody showed good maintenance of disc height.

Conclusion: We show, in these early results, that a broad footprint modular posterior interbody implant functioned well at the base of long construct surgeries for ASD patients. Expansion of this study will be needed to confirm these initial observations.