Introduction

This study investigated the binding agent Calcium/Sodium Alginate fibre gel and the addition of autogenic bone marrow aspirate (BMA) on bone growth into a porous HA scaffold implanted in an ovine femoral condyle critical-sized defect. Our hypothesis was that Alginate fibre gel would have no negative effect on bone formation and osteoconduction within the scaffold and that BMA would augment the incorporation of the graft with the surrounding bone at 6 and 12 weeks post implantation.

The size selection of the outer metal shell to fit the acetabulum is a dilemma to the surgeons for the bipolar hemiarthroplasty. However, no body ever mentioned the final results of motion behaviour of bipolar hip endoprostheses by different size selections of outer metal shell. The purpose of this study was to evaluate the motion behaviour of bipolar hip endoprostheses under different sizes of outer metal shell.

A fresh cadaver of size of 50 mm and three different sizes of bipolar hip endoprostheses were used to evaluate the motion behaviour of bipolar hip endoprostheses under the MTS machine. Each size had six sets of bipolar hip endoprostheses to get statistical data. The single axial load scaled from 300 N to 3000 N with increment of 300 N was applied on both the inner bearing and outer bearing to obtain the frictional torque of two bearings randomly. The axis was rotated from 0° to 90° under the speed of 1 deg/sec. The motion behaviour of bipolar hip endoprostheses was predicted and verified by the comparison of the frictional torque of both bearings and repeat the experiments again.

The dynamic frictional torque of 48mm was larger than the dynamic frictional torque of the 50mm at the inner bearing. The size of 52mm had the largest value of dynamic frictional torque for the outer bearing under any load condition. The prosthesis that had larger outer metal shell than the acetabulum had the same relative motion behaviour as the design hypotheses, because the difference of frictional torque was much higher.

In conclusion, the motion of the bipolar hip endoprostheses is influenced by the frictional behaviour of the both bearings. The relative motion of bipolar hip endoprostheses with a larger outer shell size will have an idea relative motion behaviour, because the larger difference of frictional torque. The thickness of the UHMWPE has a positive effect to reduce the friction between the UHMWPE liner and metal head.

We have performed a prospective single-blinded randomised study to evaluate the role of antibiotic-impregnated cement in the prevention of deep infection at primary total knee arthroplasty (TKA) in patients with diabetes mellitus. We studied prospectively 78 arthroplasties performed for osteoarthritis in such patients. They were randomly separated into two groups. In group 1 (41 knees), cefuroxime-impregnated cement was used while in group 2 (37 knees) cefuroxime was not added to the cement. The preoperative, intraoperative and postoperative management was the same for both groups. The mean follow-up was 50 months (26 to 88).

There were no cases of deep infection in group 1, but five (13.5%) occurred in group 2 (p = 0.021). We conclude that cefuroxime-impregnated cement is effective in the prevention of deep infection at primary TKA in patients with diabetes mellitus.