Antibiotic-loaded bone cements are used to decrease occurrence of bone infections in cemented arthroplasties and actually being considered as a more cost-effective procedure when compared to cementless implants [1]. However, considering the challenge of treating device-associated infections there is a reduced number of formulations in the market. Response from the industry to medical need is still slow considering the rapid change in the infecting microbial profile and the emergence of multiresistant strains [2]. In this context, the aim of the work is to evaluate the role of lactose (L), as a porogen, on the antibiotic release from bone cement (BC). Levofloxacin (Lev) and minocycline (M) were the selected antibiotics to be individually loaded into BC due to their low cost and potential application in bone infections [3,4].

Two types of matrices were prepared: 1) Loaded with 2.5% of antibiotics (controls) and 2) Loaded with 10% lactose and 2.5% antibiotic. In vitro drug release and microbiological tests against representative strains causative of bone infections were assessed.

Lactose significantly increased the release of both antibiotics. Complete minocycline release after one-week was observed (Fig.1A). Also, lactose increased 3.5-fold the levofloxacin released from BC (Fig.1B).

Furthermore, microbiological studies showed that no interaction was observed between lactose and antibiotic as no decrease in drugs antimicrobial activity was observed (Table 1).

Considering the results, L-BC matrix appears to be a valuable alternative to available formulations. Future work will include testing other antibiotics as well as mixtures of drugs.

Fundação para a Ciência e Tecnologia (Portuguese government) for financial support: EXCL/CTM-NAN/0166/2012 and strategic project PEst-OE/SAU/UI4013/2011.

Because life expectancy is increasing, the number of primary knee arthroplasties performed is projected to increase 673% by 2030, according to Westrich et al. Also, Toulson et al. in a recent study predict that the incidence of deep infection associated with primary total knee arthroplasty ranges from 1% to 2%. Periprosthetic knee infection is one of the most dramatic and difficult to manage complications following total knee arthroplasty. Therefore, periprosthetic knee infection will continue to be a significant complication and an economic burden in the future. Our objective was to identify the risk factors that may provide greater likelihood of infection and thus select high-risk patients and to take maximum prevention strategies.

Case-control study, between infected and non infected patients, undergoing primary total knee arthroplasty between January 2008 and January 2013. The risk factors evaluated were: duration of hospital stay, surgery duration, prophylactic antibiotics and timing for administration, volume of blood transfusion, autologous blood recovery system use, anesthetic technique, ASA classification, Diabetes Mellitus, Obesity (BMI>30), immunosuppression and history of any infection in the month preceding surgery. The presence of infection was defined by the criteria of the Center for Disease Control for Nosocomial Surgical Site Infections1. Statistical analysis IBM SPSS Statistics 20 (Fisher's exact test, Mann-Whitney U test and Student's t-test). Statistical significance for p ≤ 0.05.

We evaluated 540 patients with a mean follow-up of 56 months. We identified 21 deep infections (3,8%), and 35 superficial wound infections and found a positive correlation between infection and obesity (p <0.01), immunosuppression (p <0.01), volume of blood transfusion (p=0.02), history of any infection in the month preceding surgery (p <0.01). We found a negative correlation with the use of a autologous blood recovery system (p <0.01). Other factors, commonly referred in the literature, showed no association or did not reach statistical significance.

The incidence of periprosthetic knee infection after primary total knee arthroplasty stays high. The presence of obesity, immunosuppression, blood transfusion, history of any infection in the month preceding surgery were identified as significant risk factors for infection to occur. The identification, modification or eviction of the risk factors implied are essential to reduce and prevent infection in arthroplasty.

The purpose of this study is to report a unique overgrowth syndrome and discuss the insights into the complex orthopaedic management.

Written consent to report this case was granted. The patient's condition, wrongly diagnosed as Proteus syndrome, is characterised by a genetic mutation in PIK3CA, a critical regulator of cell growth. This lead to unregulated cellular division of fibroblasts isolated to the lower limbs. The legs weighed 117 kg, with a circumference of >110 cm. In addition to lower limb overgrowth, numerous musculoskeletal and organ pathologies have been encountered since birth requiring treatment from a wide variety of healthcare specialists and basic scientists. At 32 years, the patient developed septicaemia secondary to an infected foot ulcer. Amputation had been discussed in the elective setting, however the presence of sepsis expedited surgery. The above knee amputation took 9 hours and four assistants including a plastic surgeon. A difficult dissection revealed a deep subcutaneous fatty layer that integrated with deep muscle, massive hypertrophy of cutaneous nerves and the sciatic nerve and ossification within the distal quarter of the quadriceps muscles requiring osteotomy. The lower limb osteology was grossly aberrant. The size of the amputated limb did not permit use of a tourniquet and cell salvage reintroduced 10.5 litres of blood with a further 6 units of red cells intra-operatively. The leg stump successfully took to a split-skin graft. A unique phenomenon was witnessed post-operatively whereby the stump continued to grow due to upregulation of fibroblasts secondary to trauma. Targeted genetic therapies have been successfully developed to suppress this stump growth.

This unique and unclassified overgrowth syndrome was caused by a mutation in the PIK3CA gene. Orthopaedic management of the oversized limb was complex requiring multiple surgeons and prolonged general anesthetic. A multi-disciplinary approach to this condition is required for optimizing outcomes in these patients.