Jeffrey M. Toth, Mei Wang, Joshua Lawson, Jeffrey M. Badura and Kimberly Bailey DuBose
The objective of this study was to evaluate bone grafts consisting of rhBMP-2 on an absorbable collagen sponge with a ceramic composite bulking agent, rhBMP-2, directly on a ceramic-collagen sponge carrier or iliac crest bone graft (ICBG) in combination with local bone graft to effect fusion in a multisegmental instrumented ovine lumbar intertransverse process fusion model.
Thirty-six sheep had a single treatment at 3 spinal levels in both the right and left intertransverse process spaces. Group 1 sheep were treated with 7.5 cm3 of autograft consisting of ICBG plus local bone for each intertransverse process space. For Groups 2–4, 4 cm3 of local bone was placed within the intertransverse process space followed by 4.5–5 cm3 of the rhBMP-2 graft material. Group 2 animals received 1.5 mg/cm3 rhBMP-2 on an absorbable collagen sponge with a commercial bone void filler consisting of Type I lyophilized collagen with a biphasic hydroxyapatite/β-tricalcium phosphate ceramic with local bone. Group 3 animals received 0.75 mg/m cm3 of rhBMP-2 on a collagen ceramic sponge carrier with local bone. Group 4 animals received 1.35 mg/cm3 of rhBMP-2 on the same collagen ceramic sponge carrier with local bone. Sheep were euthanized 6 months postoperatively. Manual palpation, biomechanical testing, CT, radiography, and undecalcified histology were performed to assess the presence of fusion associated with the treatments.
All animals in Groups 2–4 that received grafts containing rhBMP-2 achieved radiographic and CT fusion at all 3 levels. In Group 1 (bone autograft alone), only 19% of the levels demonstrated radiographic fusion, 14% resulted in possible radiographic fusion, and 67% of the levels demonstrated radiographic nonfusion. Biomechanical testing showed that Groups 2–4 demonstrated similar stiffness of the L2–5 segment in all 6 loading directions, with each of the 3 groups having significantly greater stiffness than the autograft-only group. In Group 1, only 2 of 18 levels were rated as achieving bilateral histological fusion, with an additional 3 levels showing a unilateral fusion. The majority of the treated levels (13/18) in Group 1 were scored as histological nonfusions. There were no histological nonfusions in Groups 2 through 4. All 18 levels in Group 2 were rated as bilateral histological fusions. A majority (34/36) of the levels in Group 3 were rated as bilateral histological fusions, with 2 levels showing a unilateral fusion. A majority (35/36) of the levels in Group 4 were rated as bilateral histological fusions, with 1 level showing a unilateral fusion.
In the ovine multilevel instrumented intertransverse process fusion model, rhBMP-2 was able to consistently achieve CT, radiographic, biomechanical, and histological fusion. Compared with ICBG, the gold standard for bone grafting, rhBMP-2 was statistically superior at achieving radiographic and histological fusion.
R. Michael Meyer, M. Benjamin Larkin, Nicholas S. Szuflita, Chris J. Neal, Jeffrey M. Tomlin, Rocco A. Armonda, Jeffrey A. Bailey and Randy S. Bell
Traumatic brain injury (TBI) is independently associated with deep vein thrombosis (DVT) and pulmonary embolism (PE). Given the numerous studies of civilian closed-head injury, the Brain Trauma Foundation recommends venous thromboembolism chemoprophylaxis (VTC) after severe TBI. No studies have specifically examined this practice in penetrating brain injury (PBI). Therefore, the authors examined the safety and effectiveness of early VTC after PBI with respect to worsening intracranial hemorrhage and DVT or PE.
The Kandahar Airfield neurosurgery service managed 908 consults between January 2010 and March 2013. Eighty of these were US active duty members with PBI, 13 of whom were excluded from analysis because they presented with frankly nonsurvivable CNS injury or they died during initial resuscitation. This is a retrospective analysis of the remaining 67 patients.
Thirty-two patients received early VTC and 35 did not. Mean time to the first dose was 24 hours. Fifty-two patients had blast-related PBI and 15 had gunshot wounds (GSWs) to the head. The incidence of worsened intracranial hemorrhage was 16% after early VTC and 17% when it was not given, with the relative risk approaching 1 (RR = 0.91). The incidence of DVT or PE was 12% after early VTC and 17% when it was not given (RR = 0.73), though this difference was not statistically significant.
Early VTC was safe with regard to the progression of intracranial hemorrhage in this cohort of combat-related PBI patients. Data in this study suggest that this intervention may have been effective for the prevention of DVT or PE but not statistically significantly so. More research is needed to clarify the safety and efficacy of this practice.
Cheng H. Lo, Denis Spelman, Michael Bailey, D. James Cooper, Jeffrey V. Rosenfeld and John E. Brecknell
The authors explored the relationship among the duration of external ventricular drainage, revision of external ventricular drains (EVDs), and cerebrospinal fluid (CSF) infection to shed light on the practice of electively revising these drains.
In a retrospective study of 199 patients with 269 EVDs in the intensive care unit at a major trauma center in Australasia, the authors found 21 CSF infections. Acinetobacter accounted for 10 (48%) of these infections. Whereas the duration of drainage was not an independent predictor of infection, multiple insertions of EVDs was a significant risk factor. Second and third EVDs in previously uninfected patients were more likely to become infected than first EVDs. An EVD infection was initially identified a mean of 5.5 ± 0.7 days postinsertion (standard error of the mean); these data—that is, the number of days—were normally distributed.
This pattern of infection is best explained by EVD-associated CSF infections being acquired by the introduction of bacteria on insertion of the drain rather than by subsequent retrograde colonization. Elective EVD revision would be expected to increase infection rates in light of these results, and thus the practice has been abandoned by the authors' institution.
Phoenix, Arizona • March 6–9, 2013