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Local prophylaxis with antibiotic-loaded bone cement is a successful method to prevent post-operative infections in patients receiving orthopaedic implants. No comparable method is available for uncemented implants. Therefore, a hydrogel consisting of hyaluronic and polylactic acids was evaluated in a rabbit model for delivery of antimicrobial agents to prevent post-operative infections. In a pilot study, the suitability of the in vivo model was assessed by testing the hydrogel as carrier material for antimicrobial agents.In the main study, the antimicrobial-agent-loaded hydrogel was evaluated for infection prophylaxis. Rabbits received a titanium rod intramedullary in the tibia after contamination with Staphylococcus aureus. The rods were coated with unloaded hydrogel (Gel), hydrogel loaded with 2 % (Van2) or 5 % vancomycin (Van5), bioactive glass (BAG) or N-acetyl-L-cysteine (NAC). To analyse the infection severity after 28 d, histopathological, bacteriological, micro-computed tomographic and haematological analyses were performed. In the pilot study, the Van5 group had less infection (0/6 infected) as compared to the Gel group (5/5, p = 0.000) and the in vivo model was deemed suitable. In the main study, in the Van2 and Van5 groups, the number of infected animals was lower [1/6 (p = 0.006) and 2/6 (p = 0.044) infected, respectively]. In contrast, BAG and NAC groups showed no infection reduction (5/6 both groups, p = 0.997). The hydrogel can be used as a local carrier of vancomycin for prophylaxis of implant-related infections.The present study showed promising results for local delivery of antibacterial agents by hydrogel to prevent implant-related infections.

Background In youngsters with haemophilia most intra-articular bleedings occur in the ankle joint. Already during adolescence haemophilic arthropathy restricts their activities and participation in society. Joint distraction, an effective treatment in ankle osteoarthritis [1], has the advantage of preservation of the original joint without compromising subsequent conservative surgeries like arthrodesis. Three cases evaluated in retrospect, showed good clinical and structural efficacy in haemophilic ankle arthropathy [2]. Objectives To gather prospective data on both clinical effectiveness and tissue structure changes of ankle joint distraction in patients with haemophilic arthropathy of the ankle. Methods Haemophilia patients (n=10; ≥18 and Results A 12 months follow-up is available in 3 patients. Age at time of surgery ranged from 22 to 33 years. During distraction, none of the patients experienced bleeding. Pin tract infection, commonly seen with external frame use, occurred in 2 patients, and was treated effectively with oral antibiotics. Pain scored on the visual analogue scale decreased from 65 (47-76)mm at inclusion to 9 (7-84)mm at 6 months and 12 (1-43)mm at 12 months follow-up. Functional limitations, measured by the Haemophilia Activities List and the Ankle Osteoarthritis Scale, improved in two patients at 6 months, and in all three patients at 12 months. Functional tests improved considerably in all patients at 1-year follow up. MRI revealed a decrease in volume of subchondral cysts and bone edema in all patients, and slight improvement of the joint space width in one patient (see figure). Conclusions In this first prospective study investigating the efficacy of joint distraction in haemophilic ankle arthropathy, all three patients showed clinical and structural improvement. Although preliminary results in 3 patients, these data suggest a clear efficacy. As such, joint distraction, although a major surgical procedure, may be a promising treatment in those patients not benefitting from conservative therapy postponing more rigorous surgery. In case results appear disappointing, ankle arthrodesis is not compromised in any way. References Mastbergen SC, Saris DB, Lafeber FP. Functional articular cartilage repair: here, near, or is the best approach not yet clear? Nat Rev Rheumatol. 2013 May; 9(5):277-290. Van Meegeren ME, Van VK, de KP, Van Roermund PM, Biesma DH, Lafeber FP, et al. Joint distraction results in clinical and structural improvement of haemophilic ankle arthropathy: a series of three cases. Haemophilia. 2012 Sep; 18(5):810-817. Acknowledgements This work is supported by the Dutch Arthritis Association and the World Federation of Hemophilia. Disclosure of Interest None declared