Biomimetic calcium phosphate coatings as bone morphogenetic protein delivery systems in spinal fusion.

BACKGROUND CONTEXT: Use of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to enhance spinal fusion rates. Case reports of soft-tissue swelling, ectopic bone formation, and osteolysis have recently surfaced. It is hypothesized that incorporation of rhBMP-2 within a calcium phosphate (CaP) coating may help to localize delivery and mitigate these complications. PURPOSE: To compare the characteristics of posterolateral fusion between rabbits receiving rhBMP-2 delivered via physical adsorption to a collagen sponge or rhBMP-2 incorporated within the physical structure of a CaP coating on a collagen sponge. STUDY DESIGN/SETTING: New Zealand white rabbit model of posterolateral lumbar fusion at L5-L6. METHODS: Eighteen (18) New Zealand white rabbits underwent posterolateral spinal fusion at L5-L6. Rabbits received bilateral collagen sponges that were either coated with CaP (n=3), coated with CaP and dipped in rhBMP-2 (n=3), coated with a hybrid CaP-rhBMP-2 film (n=6), or coated with a hybrid CaP-rhBMP-2 film and dipped in rhBMP-2 (n=6). Animals were followed weekly with radiographs and were sacrificed at 6 weeks. Fusion masses were further characterized by manual palpation, computed tomography, and histology. RESULTS: Radiographic evaluation showed that animals in Group 3 (incorporated BMP) fused at 4 weeks, whereas animals in Group 2 (adsorbed BMP) and Group 4 (incorporated and adsorbed BMP) fused by 6 weeks. Animals that received rhBMP-2 physically adsorbed to the collagen sponge showed extension of the fusion mass beyond the L5-L6 level in 56% of cases and bone resorption in 78%. Histology of fusion masses showed mature bone formation in animals belonging to Groups 2, 3, and 4 and extensive osteoclast recruitment in animals belonging to Groups 2 and 4. CONCLUSIONS: Delivery of rhBMP-2 via incorporation within CaP coatings results in increased rates of radiographic fusion. The burst release profile of rhBMP-2 adsorbed to surfaces, although effective in achieving fusion, may result in increased osteoclast recruitment.

Bilateral femoral artery ischemia detected by multimodality neuromonitoring during posterior scoliosis surgery: a case report.

STUDY DESIGN: Case report. OBJECTIVE: To report a case of a bilateral femoral artery ischemia detected by neuromonitoring during posterior scoliosis surgery and to review relevant literature regarding this rare complication. SUMMARY OF BACKGROUND DATA: Lower extremity ischemia is a potentially devastating risk of posterior spinal surgery. Ischemia can be a result of thrombotic occlusion or vascular compression during patient positioning. Multimodality neuromonitoring, increasingly used to prevent neurologic injury, can also detect hypoperfusion to the extremities. To date, there have been no reports of bilateral lower extremity ischemia detected by multimodality neuromonitoring during posterior spine surgery. METHODS: A 15-year-old boy with adolescent idiopathic scoliosis underwent posterior spinal fusion with instrumentation. Intraoperative changes in somatosensory-evoked potentials and motor-evoked potentials were noted 1 hour into the case, before instrumentation or the reduction maneuver. After trouble shooting methods did not localize a technical cause for the changes, the patient's lower extremities were noted to be hypoperfused and pulseless. RESULTS: The patients was repositioned and lower extremity perfused improved. Palpable distal pulses were detected. Neuromonitoring signals returned to baseline and the surgery completed. The patient had no postoperative neurologic or vascular deficits. CONCLUSION: Lower extremity ischemia secondary to prone positioning is a rare risk of posterior spinal surgery. This is the first case report of this potentially devastating, but preventable complication detected by multimodality neuromonitoring.

Detection of Epstein-Barr virus in rapidly growing fibroadenomas of the breast in immunosuppressed hosts.

Fibroadenomas are the most common benign tumors of the female breast and are associated with a slight increase in the risk of subsequent breast cancer. Multiple fibroadenomas have been described in patients after renal transplantation and are thought to be secondary to drug-related growth stimulation. Epstein-Barr virus (EBV) has been detected in many neoplasms, including breast cancer. We set out to investigate whether EBV plays a role in the development of rapidly growing fibroadenomas in immunocompromised patients. We studied 19 fibroadenomas and one invasive ductal carcinoma that developed after organ transplantation or treatment for lupus erythematosus. As a control group we included 11 fibroadenomas from non-immunocompromised patients. DNA was amplified using polymerase chain reaction (PCR) of the EBV-encoded small RNA (EBER-2) DNA sequence. EBV latent membrane protein 1 (LMP-1) transcripts were amplified using reverse transcription (RT) PCR. Immunohistochemical (IHC) staining for LMP-1 protein was performed. A total of 9 out of 20 tumors (45%) were concordantly positive by PCR and IHC. IHC stained exclusively the epithelial cells. All the fibroadenomas in non-immunocompromised patients were negative for LMP-1 (Fisher's exact test P =.0006). These data suggest that EBV is associated with fibroadenomas in this immunosuppressed population and that the infection is specifically localized to epithelial cells. This is the first study suggesting a role for EBV in the pathogenesis of fibroadenomas.