Atomic-Scale Mapping and Quantification of Local Ruddlesden-Popper Phase Variations.

The Ruddlesden-Popper (An+1BnO3n+1) compounds are highly tunable materials whose functional properties can be dramatically impacted by their structural phase n. The negligible differences in formation energies for different n can produce local structural variations arising from small stoichiometric deviations. Here, we present a Python analysis platform to detect, measure, and quantify the presence of different n-phases based on atomic-resolution scanning transmission electron microscopy (STEM) images. We employ image phase analysis to identify horizontal Ruddlesden-Popper faults within the lattice images and quantify the local structure. Our semiautomated technique considers effects of finite projection thickness, limited fields of view, and lateral sampling rates. This method retains real-space distribution of layer variations allowing for spatial mapping of local n-phases to enable quantification of intergrowth occurrence and qualitative description of their distribution suitable for a wide range of layered materials.

An articulating antibiotic spacer controls infection and improves pain and function in a degenerative septic hip.

BACKGROUND: Treating septic arthritis of the hip with coexisting advanced degenerative disease is challenging. The use of primary total hip arthroplasty (THA) has led to postoperative infection rates as high as 22%. Insertion of antibiotic spacers with subsequent reimplantation of a THA controls infection and improves pain and function in patients with periprosthetic infections. QUESTIONS/PURPOSES: We asked whether two-stage exchange for patients with degenerative joint disease (DJD) and coexisting septic arthritis would control infection and improve pain relief and function both during the period after insertion of the spacer and after conversion to THA. METHODS: We retrospectively reviewed 14 patients with severe DJD and either active or recent septic arthritis treated with débridement and insertion of a primary antibiotic-loaded cement spacer between 1996 and 2008. Ten patients underwent subsequent exchange to a permanent hip arthroplasty. Four patients did not undergo exchange to a permanent THA: two died from unrelated causes and two elected not to proceed with exchange because their spacer provided adequate function. We obtained a modified Harris hip score. The minimum clinical followup was 7 months (average, 28 months; range, 7-65 months) after insertion of the spacer. RESULTS: Mean pain scores improved from 6 to 34, and overall Harris hip scores improved from 11 to 67 at last followup with the spacer. Those who underwent definitive THA had further improvement in their mean Harris hip scores to 93. CONCLUSIONS: Articulating antibiotic spacers offer acceptable pain relief and function while the infection is treated in this unique group of patients. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.