The use of RhBMP-2 in single-level transforaminal lumbar interbody fusion: a clinical and radiographic analysis

Abstract

The "off label" use of rhBMP-2 in the transforaminal lumbar interbody fusion (TLIF) procedure has become increasingly popular. Although several studies have demonstrated the successful use of rhBMP-2 for this indication, uncertainties remain regarding its safety and efficacy. The purpose of this study is to evaluate the clinical and radiographic outcomes of the single-level TLIF procedure using rhBMP-2. Patients who underwent a single-level TLIF between January 2004 and May 2006 with rhBMP-2 were identified. A retrospective evaluation of these patients included operative report(s), pre- and postoperative medical records, and dynamic and static lumbar radiographs. Patient-reported clinical outcome measures were obtained from a telephone questionnaire and included a modification of the Odom's criteria, a patient satisfaction score, and back and leg pain numeric rating scale scores. Forty-eight patients met the study criteria and were available for follow-up (avg. radiographic and clinical follow-up of 19.4 and 27.4 months, respectively). Radiographic fusion was achieved in 95.8% of patients. Good to excellent results were achieved in 71% of patients. On most recent clinical follow-up, 83% of patients reported improvement in their symptoms and 84% reported satisfaction with their surgery. Twenty-nine patients (60.4%) reported that they still had some back pain, with an average back pain numeric rating score of 2.8. Twenty patients (41.7%) reported that they still had some leg pain, with an average leg pain numeric rating score was 2.4. Thirteen patients (27.1%) had one or more complications, including transient postoperative radiculitis (8/48), vertebral osteolysis (3/48), nonunion (2/48), and symptomatic ectopic bone formation (1/48). The use of rhBMP-2 in the TLIF procedure produces a high rate of fusion, symptomatic improvement and patient satisfaction. Although its use eliminates the risk of harvesting autograft, rhBMP-2 is associated with other complications that raise concern, including a high rate of postoperative radiculitis.

Figures

Fig. 1

Anteroposterior (a) and lateral flexion (b) and extension (c) lumbar radiographs 16 months status post a L4–L5 TLIF procedure performed with rhBMP-2. Note the bridging interbody bone between the L4 and L5 vertebral bodies and the absence of motion when comparing the flexion and extension views. Because the interbody cage itself is radiolucent, metallic markers are used in the cage to allow visualization of its position on X-ray

Fig. 2

Coronal (a) and sagittal (b) reconstructions of a lumbar CT scan performed 14 months status post a L5–S1 TLIF procedure performed with rhBMP-2. There is bone bridging the L5 and S1 vertebral bodies that is evident on both the coronal and sagittal images