Resorbable Polylactic Acid Interbody Spacers with Vertebral Autograft for Anterior Cervical Discectomy and Fusion

Abstract

Resorbable polylactic acid spinal implants have recently become commercially available. These spacers carry the advantages of allowing for clear visualization of new bone growth, eliminating the risk of pathogen transmission, and providing for consistent biomechanical quality. However, previously published reports on the use of these spacers have all utilized bone morphogenetic proteins to supplement the fusion. This report describes our early experience with the use of these devices for interbody reconstruction in anterior cervical discectomy with fusion. Twenty patients underwent an anterior cervical discectomy with fusion at 30 levels during an 18-month period. All patients were implanted with polylactic acid interbody spacers using the Smith-Robinson technique. Supplementary anterior cervical plating was applied using unicortical semiconstrained screws, and the spacers were filled with vertebral endplate autograft bone shavings. Seven of the patients were smokers, and three were diabetics. Radiographic fusion was determined with dynamic cervical spine x-rays, and clinical responses were determined using the Medical Outcomes Study Short-Form 36-Item Health Survey, Odom's criteria, Nurick scores, and functional outcome swallowing score dysphagia scores. Follow-up averaged 11.6 months. Of the 9 patients with myelopathy, all experienced clinical improvement, with the mean Nurick score improving from 2.7 to 1.3. Of the 14 patients who had radiculopathy, 9 had complete resolution of symptoms, 4 experienced some improvement, and 1 had no improvement. All 20 patients demonstrated radiographic fusion at last follow-up as demonstrated by bridging bone between the vertebral bodies and the absence of motion on dynamic x-rays. Resorbable polylactic acid interbody spacers are safe and effective for anterior cervical discectomy and fusion. Use of locally harvested vertebral endplate bone packed within the spacer is sufficient to promote fusion in anterior cervical discectomy with fusion.