Impaction bone grafting with milled human allograft is the gold standard for replacing lost bone stock during revision hip surgery. Problems surrounding the use of allograft include cost, availability, disease transmission and stem subsidence (usually due to shear failure of the surrounding allograft). Aims. To investigate various polymers for use as substitute allograft. The ideal graft would be a composite with similar mechanical characteristics as allograft, and with the ability to form de novo bone. High and low molecular weight (MW) forms of three different polymers (polylactic acid (PLA), poly (lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL)) were milled, impacted into discs, and then tested in a custom built shear testing rig, and compared to allograft. A second stage of the experiment involved the addition of skeletal stem cells (SSC) to each of the milled polymers, impaction, 8 days incubation, and then tests for cell viability and number, via fluorostaining and biochemical (WST-1, DNA) assays.Background
Methods
Skeletal stem cells (SSCs) have been used for the treatment of osteonecrosis of the femoral head to prevent subsequent collapse. In isolation SSCs do not provide structural support but an innovative case series in Southampton, UK, has used SSCs in combination with impaction bone grafting (IBG) to improve both the biological and mechanical environment and to regenerate new bone at the necrotic site. Analysis of retrieved tissue-engineered bone as part of ongoing follow-up of this translational case series.Background
Aims
Patients suffering from finger joint pain or dysfunction due to arthritis and traumatic injury may require arthroplasty and joint replacement. Single-part silicone-based implants remain the material of choice and most widely used option, although reports on their long-term clinical performance are variable. For trauma indications, patients have a high expectation of functionality necessitating the use of materials with high wear resistance and mechanical performance. A new proximal inter phalangeal (PIP) joint designed by Zrinski AG (Wurmlingen, Germany), comprising a self-mating carbon fibre reinforced polyetheretherketone (CFR-PEEK) coupling, may provide a suitable alternative. Here we describe the wear performance of the CFR-PEEK components in a PIP joint wear simulator and subsequent characterisation of the wear particles. Four proximal and distal PIP components were milled (Zrinski AG) from CFR-PEEK (Invibio Ltd, UK) and subjected to wear testing (Endo Lab ® GmbH, Germany). The test was conducted at 37°C over 5 million cycles in 25% bovine serum (refreshed every 0.5 million cycles). The load was a static force of 63N applied at a frequency of 1Hz with a flexion/extension angle of ±40°. Wear rate was determined by mass loss from each component. Pooled serum samples from the wear simulator were subjected to protein digest and the remaining particulate debris isolated by serial filtration through 10μm, 1μm and 0.1μm filters. Particle size and morphology was subsequently determined by scanning electron microscopy (SEM) (Continuum Blue, UK).Introduction
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