Introduction: There is extensive literature on the effect of vancomycin on the compression strength of plain cements, none however on antibiotic-loaded cements. The addition of vancomycin to antibiotic-loaded bone cement is common practice in revision joint replacement surgery for infection. The scope of this study was to record the effect of vancomycin addition on the compression strength of antibiotic-loaded bone cement and to compare the results with the international standard (ISO 5833–2) in order to evaluate safety in clinical use.

Materials & Methods: The formulations used were Palamed G, containing 0.55g of gentamicin; and Copal, containing 1g of gentamicin and 1g of clindamicin. Vancomycin concentrations of 2.5%, 5% and 10% per powder weight were added. The ISO requirements for the testing procedures were followed. Samples of Palamed G with 5% vancomycin and non-standardised mixing procedures were also tested, as well as samples of both bone cements without vancomycin, as controls.

Results: The mean compression strength of plain Palamed G was 91.08 MPa. With the addition of 2.5%, 5% and 10% vancomycin, the mean compression strengths were 79.82, 82.3 and 74.56 MPa respectively, a reduction of 12.36%, 9.64% and 18.13%. The mean strength of the Palamed G specimens with 5% vancomycin and non-standardised mixing was 72.88 MPa, a 19.9% reduction. The mean compression strength of the plain Copal was 86.27 MPa. With the addition of 2.5%, 5% and 10% vancomycin, the mean compression strengths were 76.59, 78.92 and 71.19 MPa respectively, a reduction of 11.22%, 8.52% and 17.48%. Copal with 10% and Palamed G with 5% vancomycin and non-standardised mixing, were the only cements with compression strengths not significantly exceeding the ISO standard of 70 MPa.

Conclusion: The addition of up to 5% vancomycin per powder weight to the antibiotic-loaded Copal and 10% to Palamed G bone cements can be considered safe. Care should be given to the mixing procedure of the cement, as it significantly affects its compression strength.

Purpose of the study: The Natural Knee (NK) SystemTM for cementless þxation, has been developed by A. Hofmann in the USA since 1988: aim of this study was to provide early results of this implant prospectively performed by a multicentre group of European surgeons. Material and Methods: Over a 2.6year period, 287 NKñs were implanted in 283 patients by 8 orthopaedic teams in 4 european countries. Mean age and body mass index was 69 years (35–91) and 29 (16–41), repectively. Diagnosis was primary arthrosis (87%), rheumatoid (9%) and post-traumatic arthritis (4%), with previous in 30%. Approach was sub-vastus in 58% and medial-patellar in 42%. Posterior cruciate ligament (PCL) was preserved in 94% of knees and patella was resurfaced in 56%: Cemented/ cementless þxation ratios were; femur, 14/86%; tibia, 24/76%; patella (160 resurfaced), 43/57%. 75.3% of knees were all cementfree. Lateral release was performed in 20% of knees. Regularly monitored clinical and radiographic follow-up data were prospectively collected with use of a FDA-Approved form with computer centralization for statistical analysis. Results: 275 knees (96% of index cohort) were clinically reviewed at 60 month average follow-up (range, 26–95 months). Radiographically (268 knees), aseptic loosening has been observed in 2 cementless TKAñs (0.7%). At 7 years, survivorship of the index group of 287 NKñs with reoperation for any cause (7 knees) and revision for aseptic loosening (2 knees) as end points was 95.7% and 97.65%, respectively. Conclusion: In non-originators orthopaedists hands, the Natural Knee system TM has provided thus far general satisfying early results as normally expected in primary TKR with such modern modular prosthesis.

Fifty-three ununited fractures with a median time since injury of 28 months were treated by electrical stimulation using pulsing electromagnetic fields. Union was achieved in 38 cases (71.7 per cent) in a median time of six months. For ununited fractures of the tibia the success rate was higher at 86.7 per cent. Previous or active sepsis, the presence of plates or nails, the age of the patient or the time since the injury did not affect the results. Analysis of the failures suggests that inadequate immobilisation, a fracture gap of more than five millimetres or the presence of a screw in the fracture gap was responsible. In four patients no cause of failure could be determined.