Evaluation of the surgical approach and treatment outcomes in patients with chronic osteomyelitis of the tibia classified as anatomic type 3 and 4, physiologic class B (Cierny-Mader).

Analysis of surgical treatment of 68 patients (average age of 45.6 years) with chronic osteomyelitis of the tibia covered the period from June 1, 2013 till January 1, 2015. There were 49 males (72%). The first (I) group included 39 patients with type 3 chronic osteomyelitis of the tibia, the second (II) group – 29 patients with type 4 osteomyelitis. The follow-up was for 1–18 months. Duration of the surgery, intraoperative blood loss, causes of osteomyelitis and the frequency of infection recurrence were evaluated.

In the group I, 33.3% of patients underwent debridement of the infected site and replacement of the bone defect with an antibiotic-laden cement spacer. In 28.2% of cases, a biodegradable antibiotic delivery system was used for the replacement. 23.1% of cases involved muscle flap coverage of the bone and tissue defect, while 15.4% – treatment with external fixation. In the group II, the proportion of cases treated with external fixation was 58.6%. It was higher than in group I (p<0.01). 27.6% of patients in this group had their defects replaced with an antibiotic-laden cement spacer, whereas 10.3% had muscle flap coverage. One patient had amputation of the tibia.

Duration of the surgery and blood loss in group II was 2.4 and 1.7 times higher than in group I. The frequency of infection recurrence in both groups was comparable (about 13%). The average time of its manifestation was 20.8 days in group II and 41.6 days in group I. Infection recurrence after muscle flap coverage was not observed. S.aureus was the most common pathogen in both groups (50–60%). Microbial associations were isolated in 28.3 and 38% of cases in groups I and II, respectively. 33.3% of patients experienced infection caused by P.аeruginosa.

Differences in the blood loss and duration of the surgery were due to the larger volume of the affected tissues in type 4 chronic osteomyelitis of the tibia. High frequency of infection recurrence was observed in patients with microbial associations and P.aeruginosa. The surgical treatment of choice for these patients might be muscle flap coverage. It is necessary to consider the type of a pathogen for systemic and local antimicrobial therapy.

To evaluate the proportion of microbial associations causing PJI, diversity of their strains and impact on treatment failure after the removal of the hip implant and insertion of a spacer.

Spectrum of pathogens in 189 cases of PJI was studied retrospectively. Strains were isolated from the joint aspirates, tissue samples and removed orthopedic devices. The cohort comprised 144 cases of PJI after primary THA and 45 cases after the hip replacement revision surgery. All patients underwent first stage of two-stage revision procedure which involves the removal of a hip implant, debridement of infected periprosthetic tissues and subsequent insertion of a bone cement spacer. There were 92 males and 97 females (median age of 57 yrs). Statistical analysis of the results was performed with GraphPad Prism 6.0 (California, USA).

Microbial associations were detected in 28.6% (n=54) of PJI cases. Gram-positive bacteria prevailed in both groups with mono- and polymicrobial etiology. There were 52.5% of S. aureus isolates in monomicrobial group and 25% isolates in polymicrobial group (p=0.0002). This also included 8.4 and 20.6% isolates of MRSA, respectively (p<0.0001). CNS were detected in 20.1% of mono- and 27.9% of polymicrobial infection isolates, including about 40% of MRSE in both groups. Gram-negative pathogens accounted for 25.7% of isolates in polymicrobial group and 14.1% in monomicrobial group (p=0.022). Non-fermenting bacteria prevailed among Gram-negative strains presented in associations. Acinetobacter sp. and P. aeruginosa were identified in 7.4% (p=0.043) and 5.1% (p=0.56) of polymicrobial isolates. The percentage of treatment failure after the removal of the hip implant and insertion of a spacer was considerably higher (p<0.0001) in patients with polymicrobial than monomicrobial infection: 72.2 vs 25.2%, respectively. The proportion of isolates in microbial associations involving Gram-negative pathogens was 61.5% in patients with infection recurrence and 26.7% in patients with a successful outcome of the surgery (p=0.033).

Microbial associations were found in 28.6% of PJI cases after hip arthroplasty. They posed a significant risk for treatment failure after removal of the hip implant and insertion of a spacer. The multidrug-resistant strains (MRSA, Acinetobacter sp. and P. aeruginosa) were often isolated in microbial associations. Our results suggest that further study of the risk factors for polymicrobial infection is necessary in patients with PJI. Identification of a patient group at high risk for developing polymicrobial PJI will allow prescription of empiric antimicrobial therapy in time, taking into account possible multi-resistant pathogens.