Quantitative evaluation of regularized phase retrieval algorithms on bone scaffolds seeded with bone cells.

In the field of regenerative medicine, there has been a growing interest in studying the combination of bone scaffolds and cells that can maximize newly formed bone. In-line phase-contrast x-ray tomography was used to image porous bone scaffolds (Skelite(©)), seeded with bone forming cells. This technique allows the quantification of both mineralized and soft tissue, unlike with classical x-ray micro-computed tomography. Phase contrast images were acquired at four distances. The reconstruction is typically performed in two successive steps: phase retrieval and tomographic reconstruction. In this work, different regularization methods were applied to the phase retrieval process. The application of a priori terms for heterogeneous objects enables quantitative 3D imaging of not only bone morphology, mineralization, and soft tissue formation, but also cells trapped in the pre-bone matrix. A statistical study was performed to derive statistically significant information on the different culture conditions.

Nucleus disc arthroplasty with the NUBAC™ device: 2-year clinical experience.

Low back pain (LBP) due to degenerative disc disease (DDD) is a common condition that can be treated along a continuum of care: from conservative therapies to several surgical choices. Nucleus arthroplasty is an emerging technology that could potentially fill part of the gap in the spine continuum of care. The introduction of recent technologies that allow the replacement of the degenerated disc nucleus using prosthetic devices may be considered an additional therapeutic tool that can be used by the surgeon in selected cases of LBP due to DDD. Nucleus arthroplasties are designed to treat early stages of DDD, which are one of the most common spinal disorders in the population under 65 years of age. NUBAC™ is the first articulating nucleus disc prosthesis, designed to optimally respect the lumbar anatomy, kinematics, and biomechanics, constructed in unique two-piece manufactured from polyetheretherketone (PEEK) with an inner ball/socket articulation. The optimal indications for NUBAC™ implantation are: disc height >5 mm, degenerative disc changes at an early stage (Pfirmann 2, 3), single level affection, integrity of posterior facet joints, lack of local anatomical contraindication, failure of conservative treatment for at least 6 months. From December 2006 to January 2009, a total of 39 patients underwent nucleus disc arthroplasty with NUBAC™ device. 22 cases have 2-year follow up. There have been no major intra-operative or post-operative vascular or neurological complications in this series. The data showed that there were significant decreases in both Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) after the procedure, with a meaningful improvement of symptoms in all patients. Although preliminary, the initial results are encouraging. The absence of any major intra-operative and post-operative complications supports the design rationale of the NUBAC™, being less invasive comparing to total disc replacement (TDA) and with a low rate of surgical risk. The effectiveness of data as seen in 2-year follow-up on both VAS and ODI have also suggested that the NUBAC™ could be considered a viable treatment option for patients with LBP caused by DDD.