420 - Complications with rhBMP-2 in Lateral Approach Spine Surgery...

#420 Complications with rhBMP-2 in Lateral Approach Spine Surgery

Oral Posters: MIS

Presented by: W. Smith

Author(s):

W.D. Smith (1)
C.R. Brown (2)
L. Pimenta (3)
L. Marchi (3)
J.S. Uribe (4)

(1) University Medical Center of Southern Nevada, Neurosurgery, Las Vegas, NV, USA
(2) Duke University Medical Center, Department of Orthopaedic Surgery, Durham, NC, USA
(3) Instituto de Patologia da Coluna, Sao Paulo, Brazil
(4) University of South Florida, Department of Neurosurgery and Brain Repair, Tampa, FL, USA

Abstract

Introduction: Recently, risks associated with the use of rhBMP-2 have been more closely examined in spine fusion. The risks have largely been attributed to an early inflammatory reaction (resorptive phase) which has led, in some studies, to increased rates of subsidence, osteolysis, and injury to neural structures. This work examines cases of profound rhBMP-2-related complications in anterior lumbar interbody fusion performed using a lateral approach.

Methods: Cases of severe rhBMP-2 complications following extreme lateral interbody fusion (XLIF®, NuVasive, Inc.) were collected from four institutions.

Results: Six (6) cases of severe complication specific to the lateral approach following fusion with rhBMP-2 were identified. Cases with subsidence or other radiographic findings which could have caused the complications were excluded. Three delayed-onset neurologic complications were observed. One patient developed a 1/5 strength quadriceps weakness following a L4-5 XLIF beginning between the 2- and 6-week follow-up visits, persisting to 5 years postoperative. Final diagnosis based on inflammatory MRI findings and EMG was chemical neuritis during rhBMP-2 inflammatory phase. The second case was a transient 2/5 left quadriceps weakness following L2-5 XLIF with BMP. MRI confirmed inflammation without hematoma or fluid collection. Resolved by thee months postoperative. The third case exhibited an anterior femoral cutaneous branch deficit beginning 1-week postoperatively following an L4-5 XLIF with BMP, with resolution at 6 months. Three cases of significant ectopic bone were observed following XLIF with BMP, two intrapsoas (one of which required revision) and one into the neural foramen contralateral to the approach which required a foraminotomy for revision.

Conclusions: These cases of rhBMP-2 complications are consistent with recent literature, especially in similar reports of emerging radicular symptoms within several weeks of surgery in PLIF and TLIF performed with rhBMP-2. The mechanism for extra-discal damage, in this case, is assumed to be by migration of rhBMP-2, in an overly-active inflammatory phase, to the surrounding soft tissue - in these cases to the adjacent psoas, lumbar plexus, and neural foramen.