Search

BACKGROUND CONTEXT Synthetic bone grafts are a promising alternative for the treatment of degenerative spine conditions and are available without the added drawbacks associated autografts including limited availability and donor-site morbidity. Of these synthetic materials, calcium phosphate (CaP) with a characteristic needle-shaped submicron surface topography (BCP PURPOSE This study was to evaluate the efficacy of a novel synthetic bone graft using a clinically-relevant “Boden” rabbit posterolateral spine fusion model. The synthetic bone graft comprised of CaP granules with a needle-shaped submicron surface structure (BCP STUDY DESIGN/SETTING The novel synthetic bone graft was first mixed in a 1:1 volume ratio with autologous bone (ABG). Subsequently, grafts were implanted in the rabbit posterolateral spine environment for 3 days, 6, 9 and 12 weeks. An autologous bone graft group was used as a positive control in this study. Outcomes for the test article were additionally compared to historical data for the same material (BCP OUTCOME MEASURES Spinal fusion was determined by manual palpation (MP), X-ray and µCT imaging (based on the Lenke scale), mechanical testing (range of motion testing at 12 weeks only) and histology (decalcified and undecalcified). METHODS Forty skeletally mature New Zealand white rabbits were divided into two groups and underwent single-level bilateral posterolateral intertransverse process spine arthrodesis at L4-5. Animals were euthanized after 3 days, 6, 9 and 12 weeks. RESULTS Based on all endpoints, the test group and positive control group showed an equivalent and gradual progression in bone formation and implant resorption over time, leading to mature fusion masses at 12 weeks. No adverse reactions were observed in any of the groups. Bilateral fusion rates by MP were consistent with the literature (0-40% at 6 weeks; 60-70% at 12 weeks) and similar trends were seen by histological and radiographic assessment (both X-ray and µCT). Flexion-extension and lateral bending results at 12 weeks demonstrated fusion of the treated level consistent with the MP results. The results observed for the test group were consistent with those seen historically for the same material implanted without the fibrillar collagen carrier. CONCLUSIONS These results show that BCP with needle-shaped submicron-scale surface topography (BCP FDA DEVICE/DRUG STATUS Col-BCP

BACKGROUND CONTEXT Delivery and handling of graft material during surgery can be challenging often due to the particulate nature of materials, irrigation and risk of migration. Resorbable mesh pouches (RMP) offer a simple and effective way to handle and implant particulate grafts, maintain host bone contact and avoid migration. The current RMP was composed of a PLGA mesh. Two studies were performed using a well reported single level posterolateral rabbit spinal fusion model. Study 1 evaluated the RMP prefilled with demineralized bone matrix (DBM) and used as an extender with autograft while Study 2 evaluated the RMP filled with corticocancellous iliac crest autograft. An Autograft alone group was used as a positive control group in each study. PURPOSE To confirm that a porous resorbable mesh pouch, used to facilitate placement and containment of graft material does not impede bone formation. STUDY DESIGN/SETTING Preclinical in vivo study. PATIENT SAMPLE Not applicable. OUTCOME MEASURES Not applicable. METHODS Eighty skeletally mature female New Zealand White rabbits were enrolled following ethical approval in two studies. The transverse processes were exposed and decorticated with a pneumatic high-speed burr. The implant groups were 2cc of autograft, 2cc of autograft inside the RMP, or RMP pre-filled with 2cc DBM placed on top of 1cc of autograft bilaterally in the posterolateral gutters. Fusion assessment at 3 days (n=2 per group), 4 and 8 weeks (n=5 per group) and 12 weeks (n=8 per group) included manual palpation, X-rays, Faxitron radiographs, micro CT, histology and histomorphometry for bone formation as well as polymer resorption and reaction using polarized light. Statistical analyses were performed using a non-parametric Kruskal Wallis test for manual palpation, radiographs and micro CT grading while an ANOVA was used for histomorphometry and non-destructive range of motion testing. RESULTS All animals recovered uneventfully following surgery. No adverse reactions were noted macroscopically. The positive control groups performed consistently with the model and literature. Manual palpation at 12 weeks for RMP groups was 6/8 in both studies. Radiograph and micro computed tomographic grading and pmMA histomorphometry did not detect any differences between the groups at any time point. Paraffin histology revealed no adverse reactions associated with the RMP. The RMP pre-filled with DBM and combined with autograft or filled with autograft alone remodeled in the same manner as the positive control. The RMP progressively resorbed with time and was nearly completely resorbed by 8 weeks with no adverse cellular or tissue reactions. CONCLUSIONS The RMP facilitated graft placement and handling and did not impede the biology of healing and remodeling of autograft in the single-level rabbit spine model. FDA DEVICE/DRUG STATUS Resorbable Mesh Bag (Ballast) (Approved for this indication)

BACKGROUND CONTEXT Implant design, material, surfaces, graft and surgical techniques play important roles in the success of interbody fusions and the ability to radiographically assess. PEEK's positive attributes of mechanical properties and radiolucency are maintained using a molecularly bonded submicron deposition of titanium to improve bone on-growth. Novel macroscale topography features on the endplate surfaces and inside the aperture were hypothesized to allow early bone integration and mechanical stability. PURPOSE To evaluate the effect of macroscale topography on a PEEK/Titanium composite cage in a large animal model of interbody fusion. STUDY DESIGN/SETTING Preclinical large animal model. PATIENT SAMPLE Not applicable. OUTCOME MEASURES Not applicable METHODS Lateral L45 interbody fusions were performed in 4-5-year-old ewes using a PEEK/titanium composite cage (Control group) compared to the same cage with macro 3D features on the endplate and inside the aperture (Test group). Iliac crest autograft was placed in the aperture and bilateral pedicle screws and rods for posterior stabilisation. Fusion assessment at 6 and 12 weeks (n=10 per group) included manual palpation, X-rays, mCT, tensile testing and pmMA histology. RESULTS The Test group's manual palpation was 9/10 and 10/10 at 6 and 12 weeks while the control was 4/10 and 7/10 at 6 and 12 weeks. Radiographs and mCT confirmed new bone formation in the aperture of the Control group cages with time while some areas of aperture radiolucency were present. Radiographs and mCT of the Test group cages revealed new bone formation and integration within the topography features on the endplates and inside the aperture which progressed with time. Histology confirmed the radiographic findings in the control group and integration with the host endplates and remodeled bone within the apertures in the Test group. Tensile testing demonstrated nearly a 3-fold statistically significant increase in mechanical properties at both time points for the Test group vs the control group. CONCLUSIONS The macroscale features in the Test group provided multiple opportunities for bone integration between the host endplates and graft within the aperture. Early bony integration translated to a statistically significant increase in mechanical strength compared to the control cage which did not include the same geometric features. Promising data in this clinically relevant animal model warrants further study in humans. FDA DEVICE/DRUG STATUS Shoreline RT (Approved for this indication).