RhBMP-2 in transforaminal lumbar interbody fusion (TLIF) in 328 patients: Dose related outcomes
TLIF with BMP done in 328 adults (559 discs), followed 4yrs. Complications:6 nonunions, 2 seromas, 3 bony overgrowth, all resolving with decompression. No complications occurred at 4mgBMP/disc.
Off-label use of rhBMP-2 with TLIF is common, with sporadic reports of complications (largest series: 86 patients followed 27mo). This is the largest report of TLIF with BMP, with analysis of complications and outcomes by dose, diagnosis, and surgical procedure.
We retrospectively reviewed prospectively collected outcomes on 328 consecutive adults undergoing open posterior instrumented fusion (PSF) with TLIF, PEEK cage, rhBMP-2 average 8.2mg/disc (4-12mg/disc) in 559 discs, and followed 4 years (24-83mo). Diagnosis: degenerative-141, spondy-110, scoliosis-73, kyphosis-4. Age avg 60 years (19-90 yrs), 34 smokers, 126 had prior decompression/fusion. PSF avg 3.4 levels (1-17 levels); TLIF avg 1.7 levels (1-4 levels), 1 level-149, 2 levels-127, 3 levels-48, 4 levels-4. Outcomes: VAS pain scores, Oswestry Disability Index (ODI), pain medication records, and radiographic imaging pre-op, 1 year, 2 years, and latest follow-up. Fusion was defined as bridging interspace bone, no loosening of instrumentation, no motion on flex-ext radiographs.
Nonunions: 6 patients (6/559 discs; 4 scoliosis, 1 spondy, 1 degenerative), 4/6 at L5-S1. Nonunion BMP dose: 8mg-4, 6mg-1, 4mg-1. Revision surgery for BMP-related problems: seroma-2, bony overgrowth-3, all used 6-8mgBMP/disc, all resolved. Other complications: adjacent degeneration-109 (17 revised), adjacent fracture-19 (9 scoliosis, 7 revised), infection-6, late instrumentation removal-7. Osteolysis and cage subsidence were not seen. Significant improvement was noted in VAS (pre-op-6.3, 1 yr-2.9, 2 yr-3.0, P<.001) and ODI (pre-49, 1 yr-25, 2 yr-29, P<.001), and pain medication requirements.
Instrumented PSF with TLIF, PEEK cage, and rhBMP-2 produces reliable fusion (98%) and improved outcomes in adults requiring arthrodesis. Most complications occurred in deformity patients; BMP related complications were uncommon, none at 4mg/disc dose.