In vivo evaluation of resorbable bone graft substitutes in a rabbit tibial defect model.

Calcium sulfate as a bone graft substitute is rapidly resorbed in vivo releasing calcium ions but fails to provide long-term three-dimensional framework to support osteoconduction. The setting properties of calcium sulfate however allow it to be applied in a slurry form making it easier to handle and apply in different situations. This study examines the in vivo response of calcium sulfate alone and as a carrier for a coralline hydroxyapatite in an established bilateral corticocancellous defect model in rabbits. Defects were filled flush to the anterior cortex with a resorbable porous ceramic alone and in combination with calcium sulfate slurry, calcium sulfate slurry alone or calcium sulfate pellets and examined at time points up to 52 weeks. Specimens where assessed using Faxitron X-ray, light and electron microscopy. Calcium sulfate in either slurry or pellet form does indeed support new bone formation alone however, complete filling of the bone defect is not observed. Calcium sulfate in slurry form does however improve the surgical handling of particulate bone graft substitutes such as Pro Osteon 200 R, which remained as an osteoconductive scaffold for up to 52 weeks and may have played an important role in the ultimate closure of the cortical windows.

Arthroplasty of the elbow in haemophilia.

Total elbow replacement can be a valuable option for the treatment of the elbow in haemophilia where there are associated arthropathic changes. We describe the outcome of seven elbow replacements in five consecutive patients with severe haemophilia A (native factor levels < 1%) at a mean of 42 months (25 to 65) after operation. All the patients had excellent relief of pain and improvement in function. One failure was due to infection in an immunocompromised patient with both HIV and Hepatitis C antibodies who was on anti-retroviral chemotherapy. The implant was revised at 30 months in a one-stage procedure and showed no evidence of loosening or infection 35 months later.

In vitro assessment of proximal polyethylene contact surface areas and stresses in mobile bearing knees.

Wear of the polyethylene (PE) insert in total knee arthroplasty remains a significant problem. The generation of biologically active wear particles may ultimately affect implant longevity through osteolysis or premature/catastrophic PE failure. The rate and pattern of wear is influenced by many factors, including component geometry and individual loading conditions, which determine the contact surface area and kinematics of the reconstructed knee. Contact areas and stresses at the proximal femoral-PE insert interface and distal PE-tibial interface contact surface areas were measured in nine mobile bearing total knee designs at 0, 30, 60, 90 and 110 degrees of flexion at 3600 N (5 x body weight) using a standardized test method. Proximal and, to a lesser degree, distal interface contact area footprints decreased significantly with increasing flexion angle based on the conformity of the designs, resulting in a corresponding increase in the mean and peak stresses.

A resorbable porous ceramic composite bone graft substitute in a rabbit metaphyseal defect model.

The success of converted corals as a bone graft substitute relies on a complex sequence of events of vascular ingrowth, differentiation of osteoprogenitor cells, bone remodeling and graft resorption occurring together with host bone ingrowth into and onto the porous coralline microstructure or voids left behind during resorption. This study examined the resorption rates and bone infiltration into a family of resorbable porous ceramic placed bilaterally in critical sized defects in the tibial metaphyseal-diaphyseal of rabbits. The ceramics are made resorbable by partially converting the calcium carbonate of corals to form a hydroxyapatite (HA) layer on all surfaces. Attempts have been made to control the resorption rate of the implant by varying the HA thickness. New bone was observed at the periosteal and endosteal cortices, which flowed into the centre of the defect supporting the osteoconductive nature of partially converted corals. The combination of an HA layer and calcium carbonate core provides a composite bone graft substitute for new tissue integration. The HA-calcium carbonate composite demonstrated an initial resorption of the inner calcium carbonate phase but the overall implant resorption and bone ingrowth behaviour did not differ with HA thickness.

Surface roughness of the proximal and distal bearing surface of mobile bearing total knee prostheses.

Proximal and distal articulations surface roughness measurements were done on 8 mobile bearing knee designs immediately after removal from sterile packaging. Roughness parameters Ra and Rp based on ISO 97, representing mean deviation from the smooth surface line and mean peak to smooth surface line, were recorded using a contact surface profilometer at 10 random sites in the anteroposterior and mediolateral direction on the femoral and tibial metal components and the proximal and distal surface of the ultra-high molecular weight polyethylene (PE) inserts. No differences were found for surface roughness values for the metal components. Surface roughness values were greater for the distal PE bearing surfaces compared with the proximal PE bearing surfaces for each design tested. The roughness values for the PE inserts showed a directional dependence. Complex kinematics of mobile bearing knees coupled with this rougher distal interface could influence the rate of generation of wear particles and total volume of particles produced especially in the early postoperative period.

The function of the posterior cruciate ligament in an anteroposterior-gliding rotating platform total knee arthroplasty.

Knee kinematics after total knee arthroplasty is dictated primarily by implant geometry and native soft tissue constraints. This study highlights the importance of a functioning posterior cruciate ligament in limiting excessive anteroposterior translation in a mobile bearing knee design that relies on native posterior cruciate ligament integrity and postarthroplasty tensioning for stability rather than any inherent mechanical design stability, such as anterior rails or stops.

A model curriculum vitae: what are the trainers looking for?

In this new era of Calman, the curriculum vitae (CV) still remains the most important document in furthering the careers of doctors. A survey of postgraduate deans and college regional training advisors opinions on CVs was undertaken. The results have allowed a model CV to be compiled expressing the layout and most of the features which senior trainers feel are important when producing a CV.

A simple technique for harvesting autogenous morcellized bone-graft during primary hip arthroplasty.

A technique for producing morcellized bone-graft from the femoral head for reconstituting the acetabulum in primary hip arthroplasty is described. The method is simple to perform, requires no additional equipment, and is effective.

Symmetrical Brodie's abscess.

Chronic recurrent multifocal osteomyelitis is often confused with symmetrical Brodie's abscess as it has a similar pathogenesis. We report an otherwise healthy 17-year-old boy presenting with a true symmetrical Brodie's abscess. We conclude that a symmetrical Brodie's abscess presenting in an otherwise healthy patient is a separate clinical condition with a different management protocol.