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

Revision total hip arthroplasty using the Zweymuller femoral stem

Background: A variety of femoral stem designs have been reported to be successful in revision total hip arthroplasty without consensus as to optimal design. We evaluated the clinical and radiographic outcomes in a consecutive series of femoral revisions using a wedge-shape, tapered-stem design at medium and long-term follow-up. Materials and methods: We performed a retrospective review of clinical and radiographic outcomes of twenty-eight consecutive femoral revisions arthroplasties, which were done using the Zweymuller femoral stem. Results: The mean follow-up was 7.4 years (range 2-15 years). No stem re-revision was necessary. All stems were judged to be stable by radiographic criteria at the most recent follow-up. The final mean Harris hip score was 90. There was no difference in Harris hip scores, implant stability, or radiological appearance (distal cortical hypertrophy or proximal stress shielding) of the implants between medium-term (mean 5.7 years) and long-term (mean 12.4 years) follow-up. Conclusions: We found the Zweymuller femoral stem design to be durable for revision hip arthroplasty when there is an intact metaphyseal-diaphyseal junction for adequate press-fit stability at surgery. © Springer-Verlag 2008

A systematic review of the evidence for single stage and two stage revision of infected knee replacement

BACKGROUND: Periprosthetic infection about the knee is a devastating complication that may affect between 1% and 5% of knee replacement. With over 79 000 knee replacements being implanted each year in the UK, periprosthetic infection (PJI) is set to become an important burden of disease and cost to the healthcare economy. One of the important controversies in treatment of PJI is whether a single stage revision operation is superior to a two-stage procedure. This study sought to systematically evaluate the published evidence to determine which technique had lowest reinfection rates. METHODS: A systematic review of the literature was undertaken using the MEDLINE and EMBASE databases with the aim to identify existing studies that present the outcomes of each surgical technique. Reinfection rate was the primary outcome measure. Studies of specific subsets of patients such as resistant organisms were excluded. RESULTS: 63 studies were identified that met the inclusion criteria. The majority of which (58) were reports of two-stage revision. Reinfection rated varied between 0% and 41% in two-stage studies, and 0% and 11% in single stage studies. No clinical trials were identified and the majority of studies were observational studies. CONCLUSIONS: Evidence for both one-stage and two-stage revision is largely of low quality. The evidence basis for two-stage revision is significantly larger, and further work into direct comparison between the two techniques should be undertaken as a priority

Validation of local anaesthetic hip arthrograms in the management of hip pain

Despite clinical history, examination and plain radiography it is occasionally difficult to locate the origin of hip pain. This is particularly relevant where the management will be a total hip arthroplasty. Local anaesthetic arthrogram of the hip may provide a simple, safe and reliable test to determine if the hip is the source of the patient’s symptoms. The aim of this study was to establish the use of this investigation in the management of hip pain. All local anaesthetic hip arthrograms were reviewed from 1999 to 2005. All patients had completed a pain questionnaire following the arthrogram. Patients were classified into 3 groups; 1) Mild osteoarthritic changes on plain radiographs with possible referred pathology; 2) Minimal radiological changes but no obvious other pathology to refer pain; 3) Previous hip arthroplasty with unexplained pain. Those who subsequently had a primary or revision hip arthroplasty were assessed post-operatively by means of the Oxford hip score. Fifty-seven patients in total underwent a local anaesthetic hip arthrogram. From all the groups 34 patients obtained pain relief and 24 proceeded to primary or revision hip arthroplasty. Twenty three (96%) had a satisfactory post-operative outcome at an average follow-up of 2 years (average Oxford score 28). The remaining 10 patients with positive arthrograms are still waiting for surgery. All negative arthrogram patients were successfully discharged. A positive response to local anaesthetic hip arthrogram predicts a successful response to surgery. This permits accurate information of the results of hip surgery to be given to patients and aids in a management plan for a group of patients that can be otherwise challenging