Evaluation of the effectiveness of biodegradable bone substitute with high doses of antibiotics in cavitary osteomyelitis and infected nonunions.

The authors evaluated 8 cases, 5 of them related to osteomyelitis with bone sequestration and other 3 regarding infected nonunions. All of them had in common the persistence of infection after antibiotic therapy.

All infections were confirmed by microbiological studies. In all cases the surgeons conducted a thorough surgical debridement and filling of bone defects with Herafill®. Later a tight clinical, analytical and imagiological control was performed.

Five of the cases were a success with simultaneous healing of the bone loss and treatment of the infection. These corresponded to the cases of cavitary osteomyelitis. In the remaining 3 cases, despite infection eradication, union was not achieved and additional surgical procedures were required for definitive treatment of nonunion.

In the treatment of bone infection, use of high doses of antibiotics at the site is a consensus as it allows eradication of the infection with lower systemic effects. With the emergence of biodegradable bone substitutes, the need for a new surgical intervention for their removal can be avoided. Properties of calcium sulfate and calcium carbonate stimulate osteogenesis at the site, allowing their absorption and replacement by bone matrix. These properties make them ideal to usage in cases of cavitary bone defects.

Our experience supports the idea that the use of high doses of antibiotics locally permits remission of the infection. However, when this is implemented through a bone substitute, it is possible to achieve osteogenesis in bony cavities. Nevertheless, when applied to infected nonunions, their role seems to be limited to the eradication of the infection.

Stored red blood cells (RBCs) undergo a variety of changes that impair their post-transfusion viability, but the detrimental effect of such lesion at the clinical level is a matter of debate (1) and there is no data about the incidence of postoperative infection, a complication frequently associated with transfusion of stored RBCs (2).

We reviewed 9906 patients who underwent a primary or revision arthroplasty between January 2000 and December 2012. Of these, 1153 (11.6%) received transfusion during surgery or within the first 6h after surgery (early transfusion, ET) and 920 (9.3%) received transfusion only between 24 and 96 hours after surgery (late transfusion, LT). Primary end-point was prosthetic joint infection (PJI) within the first year. Demographics, joint, type of surgery, duration of surgery, number and length of storage of transfused RBCs were collected. Ethical Committee approved the study.

The median age was 74.9 (IQR:68.3–80.1) years and 1546 (74.6%) were female. There were 914 (44.1%) hip and 1117 (53.9%) knee arthroplasties and 428 (20.6%) were revision surgeries. The median duration of surgery was 105 (IQR:80–145) minutes. A total of 100 (4.8%) patients had a PJI. Figure 1 shows the PJI rate according to the number of RBC units transfused and the proportion of such units that had been stored for more than 14 days, both in the ET-group (Fig. 1A) and the LT-group (Fig. 1B). In the ET-group, the fact that >50% of transfused RBCs had been stored >14 days was an independent predictor of PJI (OR:2.50, 95%CI:1.44–4.33, Hosmer-Lemeshow test P=0.972).

Stored RBC occlude the microcirculation (1), thereby precluding a good oxygenation of the surgical wound and the arrival of leukocytes and prophylactic antibiotics. Both factors are involved in the progression from wound bacterial contamination to wound infection and are particularly operative in the few hours following surgery (5). It is biologically plausible that transfusion of old RBC in this early, critical period results in more wound infections as compared to RBCs transfused later.