Cambridge experience in spontaneous bone regeneration after traumatic segmental bone defect: a case series and review of literature.

High-energy traumatic long bone defects are some of the most challenging to reconstruct. Although cases of spontaneous bone regeneration in these defects have been reported, we are aware of no management guidelines or recommendations for when spontaneous bone regeneration should be considered a viable management option. We aim to identify how certain patient characteristics and surgical factors may help predict spontaneous bone regeneration. A total of 26 cases with traumatic segmental defects were treated at our institution, with eight cases (30.8%) undergoing spontaneous regeneration. We discuss four in detail. Six (75%) reported a degree of periosteal preservation, four (50%) were associated with traumatic brain injury and none were complicated by infection. The average time to spontaneous bone regeneration was 2.06 months. According to our cases, patients with favourable characteristics may benefit from delaying surgical treatment by 6 weeks to monitor for any signs of spontaneous bone formation.

Optimizing surface characteristics for cell adhesion and proliferation on titanium plasma spray coatings on polyetheretherketone.

BACKGROUND: Titanium plasma spray coating on polyetheretherketone (PEEK) is a recent innovation to interbody spacer technology. The inherent hydrophobic properties of standard, uncoated PEEK implants can hamper cell attachment and bone healing during fusion. The addition of titanium coating not only offers initial stability due to increased surface roughness but also long-term stability due to bony ongrowth created from osteoconductive microenvironment on the device surface. The previously established hydrophilic and osteophilic properties of commercially pure titanium (CPTi) can potentially provide an ideal environment promoting cell attachment and bony ongrowth when applied at the end plate level of the fusion site. Because the surface material composition and topography is what seems to directly affect cell adhesion, it is important to determine the ideal titanium coating for the highest effectiveness. PURPOSE: The purpose of the study is to determine whether there is an optimal surface roughness for the titanium coatings and whether different polishing methods have a greater effect than roughness or topography in mediating cell adhesion to the surface. STUDY DESIGN/SETTING: The study was divided into two phases. In Phase 1, the effects of varying surface roughnesses on identical polishing method were compared. In Phase 2, the effect of varying polishing methods was compared on identical surface roughnesses. METHODS: Coating thickness, porosity, and surface roughness were characterized using an optical microscope as per ASTM F 1854 standards. For both phases, PEEK coupons with plasma-sprayed CPTi were used, and human mesenchymal stem cells (hMSCs) at an initial density of 25,000 cells/cm2 were seeded and cultured for 24 hours before fixation in 10% formalin. The cultured hMSCs were visualized by 4',6-diamidino-2-phenylindole (DAPI) staining, a fluorescent stain that binds to the DNA of living cells. Samples were imaged using an environmental scanning electron microscope (eSEM) (Carl Zeiss Microscopy, Thornwood, NY, USA) using a backscattered detector. RESULTS: Image analysis of the CPTi coatings showed uniform and rough surfaces. For Phase 1, roughness was evaluated as fine, medium, and coarse. The eSEM image analysis and cell counting by DAPI demonstrated that hMSCs have a tendency to form stronger adhesion and greater pseudopodia extensions on fine roughness surfaces. Individual hMSCs were seen forming cytoplasmic processes extending across the width of a pore. There was a 4- and 20-fold reduction in adhered hMSCs with an increase to medium and coarse roughnesses, respectively. For Phase 2, studied groups are (1) medium CPTi coating with zirconia polishing, (2) medium CPTi coating with CPTi polishing, and (3) fine CPTi coating with CPTi polishing. The eSEM image analysis and cell counting by DAPI demonstrated that hMSCs have a tendency to form stronger adhesion and greater pseudopodia extensions on Group 3 over the other two groups. There was a twofold reduction in adhered hMSCs on medium roughness relative to fine. No difference in cell adhesion was found between Groups 1 and 2. Individual hMSCs were seen forming cytoplasmic processes extending across the width of a pore. CONCLUSIONS: Previously, it was accepted without much scrutiny that surface coatings were beneficial. This study begins to discover that surface topography directly affects the potential for cells to adhere and proliferate and lead to greater surgical efficacy.

Incidence of vascular complications during lateral lumbar interbody fusion: an examination of the mini-open access technique.

PURPOSE: This article examines the incidence and management of vascular injury during Lateral Lumbar Interbody Fusion (LLIF). The details of the mini-open access technique are presented. METHODS: A total of 900 patients who underwent a LLIF at an average 1.94 levels (range: 1-5 levels) by one of six fellowship trained surgeons on 1,754 levels from 2006 to 2013 were identified. The incidence of intraoperative vascular injury was retrospectively determined from the Operative Records. The management of vascular injury was evaluated. The mini-open access adapted by our institution for LLIF is described. RESULTS: The incidence of major vascular complication in our series was 1/900. The incidence of minor vascular injury was 4/900. The overall incidence of vascular injury was calculated to be 0.056 % per case and 0.029 % per level. All minor vascular injuries were identified to be segmental vessel lacerations, which were readily ligated under direct visualization without further extension of the incision with no clinical sequelae. The laceration of the abdominal aorta, the major vascular complication of this series, was emergently repaired through an exploratory laparotomy. None of the patients suffered long-term sequelae from their intraoperative vascular injuries. CONCLUSIONS: The mini-open lateral access technique for LLIF provides for minimal risk of vascular injury to the lumbar spine. In the rare event of minor vascular injury, the mini-open access approach allows for immediate visualization, confirmation and repair of the vessel with no long-term sequelae.