Elective hip arthroplasty rates and related complications in people with diabetes mellitus.

BACKGROUND AND AIMS: Diabetes mellitus (DM), poor glycaemic control and raised body mass index (BMI) have been associated with postoperative complications in arthroplasty, although the relative importance of these factors is unclear. We describe the prevalence of DM in elective hip arthroplasty in a UK centre, and evaluate the impact of these factors. METHODS: We analysed retrospective data for DM patients undergoing arthroplasty over a 6-year period and compared with non-diabetic matched controls (1 DM patient: 5 controls). DM was present in 5.7% of hip arthroplasty patients (82/1443). RESULTS: Postoperative complications occurred in 12.2% of DM patients versus 12.9% of controls (p = 1.000); surgical complications were present in 6.1% of those with DM and 2.4% of controls (p = 0.087), while medical complications occurred in 8.5% of DM patients versus 10.7% of controls (p = 0.692). Complications developed in 23.1% of DM patients with poor glycaemic control (HbA1c > 53 mmol/mol) versus 9.8% with good control (p = 0.169). In DM patients and controls combined, complications occurred in 16.3% of obese patients versus 10.0% of non-obese patients (p = 0.043). In the DM cohort, 13.7% of overweight patients had complications versus 0% with a normal or low BMI (p = 0.587). CONCLUSIONS: DM rates were lower than expected, and glycaemic control was good. Overall complication rates were unrelated to the presence of DM or to glycaemic control, although surgical complications were observed more frequently in those with DM and poor glycaemic control was uncommon within our cohort. Complications were more frequent in those with a higher BMI. Whether some patients with DM but without an increased risk of complications are currently being excluded from surgery requires exploration.

Processed versus fresh frozen bone for impaction bone grafting in revision hip arthroplasty.

BACKGROUND: Impaction grafting is a technique to restore bone loss both in the femur and the acetabulum during revision hip arthroplasty surgery. Initially impaction grafting was undertaken using fresh frozen femoral head allografts that were milled to create morselized bone pieces that could be impacted to create a neo-cancellous bone bed prior to cementation of the new implant. Results of medium and long term outcome studies have shown variable results using this technique. Currently both processed and non-processed allograft bone are used and the purpose of this review was to analyse the evidence for both. OBJECTIVES: To determine the clinical effectiveness of processed (freeze dried or irradiated) bone in comparison to fresh frozen (unprocessed) bone. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1985 to 2008), EMBASE (1985 to 2008), CINAHL(1985 to 2008) and the National Research Register. Additional sources were also searched. Handsearching of relevant journals and conference abstracts was also undertaken. Searches were complete to 31 August 2008. SELECTION CRITERIA: Randomised controlled trials that compared different types of bone for impaction grafting. DATA COLLECTION AND ANALYSIS: Three hundred and sixty references were identified from the searches. Following detailed eligibility screening, three hundred and fifty nine references did not meet the eligibility criteria. Further details are required about one trial in order to determine it's eligibility. MAIN RESULTS: No trials were identified that met the criteria for inclusion in the review. AUTHORS' CONCLUSIONS: Good quality randomised controlled trials are required in this area so that a surgeon's choice of bone graft can be informed by evidence rather than personal preference.

Bone and cartilage differentiation of a single stem cell population driven by material interface.

Adult stem cells, such as mesenchymal stem cells, are a multipotent cell source able to differentiate towards multiple cell types. While used widely in tissue engineering and biomaterials research, they present inherent donor variability and functionalities. In addition, their potential to form multiple tissues is rarely exploited. Here, we combine an osteogenic nanotopography and a chondrogenic hyaluronan hydrogel with the hypothesis that we can make a complex tissue from a single multipotent cell source with the exemplar of creating a three-dimensional bone-cartilage boundary environment. Marrow stromal cells were seeded onto the topographical surface and the temperature gelling hydrogel laid on top. Cells that remained on the nanotopography spread and formed osteoblast-like cells, while those that were seeded into or migrated into the gel remained rounded and expressed chondrogenic markers. This novel, simple interfacial environment provides a platform for anisotropic differentiation of cells from a single source, which could ultimately be exploited to sort osteogenic and chondrogenic progenitor cells from a marrow stromal cell population and to develop a tissue engineered interface.

Nanopit-induced osteoprogenitor cell differentiation: The effect of nanopit depth.

We aimed to assess osteogenesis in osteoprogenitor cells by nanopits and to assess optimal feature depth. Topographies of depth 80, 220 and 333 nm were embossed onto polycaprolactone discs. Bone marrow-derived mesenchymal stromal cells were seeded onto polycaprolactone discs, suspended in media and incubated. Samples were fixed after 3 and 28 days. Cells were stained for the adhesion molecule vinculin and the osteogenic transcription factor RUNX2 after 3 days. Adhesion was lowest on planar controls and it was the shallowest, and 80-nm-deep pits supported optimal adhesion formation. Deep pits (80 and 220 nm) induced most RUNX2 accumulation. After 28 days, osteocalcin and osteopontin expression were used as markers of osteoblastic differentiation. Deep pits (220 nm) produced cells with the highest concentrations of osteopontin and osteocalcin. All topographies induced higher expression levels than controls. We demonstrated stimulation of osteogenesis in a heterogeneous population of mesenchymal stromal cells. All nanopit depths gave promising results with an optimum depth of 220 nm after 28 days. Nanoscale modification of implant surfaces could optimise fracture union or osteointegration.

Investigation of the limits of nanoscale filopodial interactions.

Mesenchymal stem cells are sensitive to changes in feature height, order and spacing. We had previously noted that there was an inverse relationship between osteoinductive potential and feature height on 15-, 55- and 90 nm-high titania nanopillars, with 15 nm-high pillars being the most effective substrate at inducing osteogenesis of human mesenchymal stem cells. The osteoinductive effect was somewhat diminished by decreasing the feature height to 8 nm, however, which suggested that there was a cut-off point, potentially associated with a change in cell-nanofeature interactions. To investigate this further, in this study, a scanning electron microscopy/three-dimensional scanning electron microscopy approach was used to examine the interactions between mesenchymal stem cells and the 8 and 15 nm nanopillared surfaces. As expected, the cells adopted a predominantly filopodial mode of interaction with the 15 nm-high pillars. Interestingly, fine nanoscale membrane projections, which we have termed 'nanopodia,' were also employed by the cells on the 8 nm pillars, and it seems that this is analogous to the cells 'clinging on with their fingertips' to this scale of features.

Scanning electron microscopical observation of an osteoblast/osteoclast co-culture on micropatterned orthopaedic ceramics.

In biomaterial engineering, the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. On contact with an implant, bone marrow-derived mesenchymal stromal cells demonstrate differentiation towards bone forming osteoblasts, which can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of bone marrow-derived mesenchymal stromal cells with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina ceramics with 30 µm diameter pits. The aim was to establish whether the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropatterns towards osteogenesis, with more nodule formation and less osteoclastogenesis compared to planar controls. In addition, we found that that macrophage and osteoclast-like cells did not interact with the pits and formed fewer full-size osteoclast-like cells on the pitted surfaces. This may have a role when designing ceramic orthopaedic implants.