We present a review of 97 consecutive BioPro. ®. metallic hemiarthroplasties performed in 80 patients for end-stage hallux rigidus, with a minimum of five years follow-up. The mean age of the cohort was 55 (22 to 74) years. No patient was lost to follow-up. There were 15 revisions performed, one for infection, two for osteolysis, and 12 for pain. The all cause survival rate at five years was 85.6% (95% confidence interval (CI) 83.5 to 87.9). Younger age was a significant predictor of revision (odds ratio 1.09, 95% CI 1.02 to 1.17, p=0.014) on excluding infection and adjusting for confounding variables (Cox regression). Significant improvements were demonstrated at 5 years in the Manchester Oxford foot questionnaire (13.9, 95% CI 10.5 to 17.2) and in the physical component of the short form 12 score (6.5, 95% CI 4.1 to 8.9). The overall satisfaction rate was 72%. The cost per quality-adjusted-life-year at 5 years, accounting for a 3% per year revision rate, was £3,714. The BioPro offers good short to mid-term functional outcome and is a cost effective intervention. The relative high revision rate is associated with younger age and the use of this implant may be limited to older patients

Background. An improved understanding of intervertebral disc (IVD) structure and function is required for treatment development. Loading induces micro-fractures at the interface between the nucleus pulposus (NP) and the annulus fibrosus (AF), which is hypothesized to induce a cascade of cellular changes leading to degeneration. However, there is limited understanding of the structural relationship between the NP and AF at this interface and particularly response to load. Here, X-ray scattering is utilised to provide hierarchical morphometric information of collagen structure across the IVD, especially the interface region under load. Methodology. IVDs were imaged using the I22 SAXS/WAXS beamline at Diamond Light Source. Peaks associated with the D-banded structure of collagen fibrils were fitted to quantify their azimuthal distribution, as well the magnitude and direction of internal strains under static and applied strain (0–20%). Results. IVD tissue regions exhibited structural “AF-like” and “NP-like” fingerprints. Demonstrating high internal strains on collagen fibres particularly within the NP region of the disc. AF and NP regions showed distinct collagen orientation and internal strains with an apparent lack of bracing structure seen at the interface between the differential mechanical tissues. X-ray scattering under tensile strain provided structural information at high resolution, with clear differences observed between normal and degenerate discs under load. Conclusion. X ray scattering has been utilised to develop an improved understanding of collagen structure across the intervertebral disc which can be utilised to gain an increased understanding of load induced propagation of micro fissures and disc degeneration. Conflict of Interest: No conflict of interest. Funding: BioPro Network, UCL for funding this study through support from the MRC (MR/R025673/1)