Bioactive glass S53P4 as bone graft substitute in treatment of osteomyelitis

Abstract

Bioactive glass (BAG)-S53P4 is an osteoconductive bone substitute with proven antibacterial and bone bonding properties. In a multicentre study 11 patients with verified chronic osteomyelitis in the lower extremity and the spine were treated with BAG-S53P4 as a bone substitute. The cavitary bone defect and the surrounding of a spinal implant were filled with BAG-S53P4. The most common pathogen causing the infection was Staphylococcus aureus. The mean follow-up was 24 months (range 10–38). BAG-S53P4 was well tolerated. Nine patients healed without complications. One patient who achieved good bone formation sustained a superficial wound infection due to vascular problems in the muscle flap, and one patient had an infection due to a deep haematoma. This study shows that BAG-S53P4 is a good and well-tolerated bone substitute, and can be used in treatment of osteomyelitis with good primary results.

Introduction

Osteomyelitis, first described by Chassaignac in 1852, is caused by infecting micro-organisms and defines a destructive inflammatory process in bone that is often accompanied by bone destruction [1]. The infection can arise from a variety of aetiologies [2]. Most often it is caused by trauma, but any kind of bone or soft tissue surgery where pathogens can enter the bone, may cause the infection. In diabetic patients, osteomyelitis may appear as a secondary manifestation due to vascular insufficiency and soft tissue infection [3]. Haematogenous osteomyelitis has been found in children, as well as in elderly patients [4].

Acute osteomyelitis is an infection characterized by oedema, locally decreased blood supply and pus formation. Untreated or due to treatment failure, the infection can progress to a more chronic phase, with formation of a large area of devascularized dead bone, a sequestrum. In treatment of chronic osteomyelitis, adequate debridement is mandatory. Unfortunately, this treatment often results in a poorly vascularized large bone defect, a dead space. Bacterial infection can also cause local acidosis, leading to dissolution of bone matrix mineral [5]. Many different methods have been used to treat the bone defect and the infection, including free vascularized bone grafts, local muscle flaps, antibiotic-impregnated polymethyl methacrylate (PMMA) beads, granulation formation according to the technique of Papineau and the Masquelet technique [6] or bone reconstruction based on Ilizarov technology [7].

Staphylococcus aureus and Gram-negative bacilli are the pathogens most commonly involved [7]. The bacterial colonization of host tissue or implanted materials is promoted by the ability of the bacteria to produce protein-specific adhesins on their surfaces, which is followed by interactions with host protein components, such as fibrinogen, fibronectin and collagen. Bacteria also have sophisticated methods for communication through hormone-like compounds in biofilms, making treatment with antimicrobial agents difficult [2]. Use of synthetic bone graft substitutes in treating osteomyelitis is, therefore, generally not recommended.

Bioactive glasses (BAGs) are synthetic biocompatible osteoconductive bone substitutes, with bone bonding capacity and documented antibacterial and angiogenesis-promoting properties [8], [9], [10], [11], [12], [13], [14], [15], [16]. Previous studies on atrophic rhinitis, a chronic purulent disorder often caused by Klebsiella ozaenae and difficult to treat, have shown that BAG-S53P4 does not favour adhesion or colonization of K. ozaenae on its surface. In addition, K. ozaenae cannot form biofilms on BAG-S53P4 [17].

The aim of this study was to apply the experimentally known antibacterial properties of BAG-S53P4 to clinical practice, evaluating the operative outcome using BAG-S53P4 as a bone graft substitute in treating osteomyelitis.