Evaluation of bone substitute material based on polyurethane polymers for treatment of chronic osteomyelitis (experimental morphological study)

Introduction Treatment of patients with post-osteomyelitic defects is one of the most challenging areas in traumatology and orthopedics.

Purpose To substantiate, on an experimental model, the potential of a partially bioresorbable material Rekost used to compensate for osteomyelitic cavities in combination with an antibiotic.

Materials and methods The study was performed on nine male Soviet Chinchilla rabbits (16–18 months old, 4.3–4.5 kg of weight), in which osteomyelitis was modeled in the proximal metaphysis of the tibia by producing a trepanation hole and installing an Osteolite™ containing a Staphylococcus aureus culture. The animals were divided into three groups. Animals in group 1 were withdrawn from the experiment after 21 days of osteomyelitis modeling. In groups 2 and 3, the second stage included sequestronecrectomy and substitution of the bone defect thus formed with Rekost material (OOO AikonLabGmbh, Nizhny Novgorod, RZN 2014/1646 dated 03.07.2014, for indefinite) impregnated with an antibiotic in group 3. After 21 days of implantation, the animals were withdrawn from the experiment. Clinical, radiological, biochemical and histological methods were used.

Results In Group 1, signs of osteomyelitis were recorded: necrotic fragments of bone trabeculae, inflammatory infiltrate, osteoclastic resorption and osteogenesis, bone marrow fibrosis, and pronounced CD15 expression. In groups 2 and 3, three weeks after implantation, a network of newly formed bone trabeculae at the bone-material interface was noted, and bone trabeculae were observed in the implant cavities. In the epiphysis of group 2, a HOES score of ≥ 6 points corresponded to active chronic osteomyelitis. In group 3, a median HOES score of 2 points indicated a remission of chronic osteomyelitis, and CD15 marker expression was less pronounced than in group 2. C-reactive protein levels continued to increase in Group 2 and significantly decreased in Group 3.

Discussion Bioresorbable implants, impregnated with antibiotics, provide gradual replacement of the material with bone tissue, eliminate the need for repeated surgeries, reduce the risk of chronic infection, and are biocompatible.

Conclusion In an in vivo experimental model, minimal degradation of the Rekost material was observed three weeks after implantation, manifested by highly frequent foreign-body-type giant multinucleated cells. Early data on the osteoplastic properties of the Rekost material and its ability to suppress infection and inflammation in combination with an antibiotic suggest the potential for further experimental studies of this product to be used in the treatment of patients with chronic osteomyelitis.

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