Search

Chronic osteomyelitis has always been a therapeutic challenge for patient and surgeon due to the specific problems related with bone infection and bacterial biofilm eradication. Other than being the cause of infection or facilitating spread or persistence of infection, biomaterials are also becoming a tool in the treatment of infection. Certain novel biomaterials have unique and ideal properties that render them perfectly suited to combat infection and are therefore used more and more in the treatment of chronic bone infections. In case of infection treatment, there is still debate whether these properties should be focused on bone regeneration and/or their antimicrobial properties. These properties will be of even greater importance with the challenge of emerging antimicrobial resistance. This review highlights indications for use and specific material properties of some commonly used contemporary biomaterials for this indication as well as clinical experience and a literature overview.

Seating a cementless acetabular cup via impaction is a balancing act; good cup fixation must be obtained to ensure adequate bone in‐growth and cup apposition, while acetabular fracture must be avoided. Good impaction technique is essential to the success of hip arthroplasty. Yet little guidance exists in the literature to inform surgeons on ‘how hard’ to hit. A drop rig and synthetic bone model were used to vary the energy of impaction strikes in low and high density synthetic bone, while key parameters such as dynamic strain (quantifying fracture risk), implant fixation and polar gap were measured. For high energy impaction (15 J) in low density synthetic bone a peak tensile strain was observed during impaction that was up to 3.4x as large as post‐strike strain, indicating a high fracture risk. Diminishing returns were observed for pushout fixation with increasing energy. 85% of the pushout fixation achieved using a 15 J impaction strike was attained by using a 7.5 J strike energy. Similarly polar gap was only minimally reduced at high impaction energies. Therefore it is suggested that higher energy strikes increase fracture risk, but do not offer large improvements to fixation or implant‐bone apposition. It may difficult be for surgeons to accurately deliver specific impaction energies, suggesting there is scope for operative tools to manage implant seating.

Wear of metal-on-metal (cobaltchromium, CoCr particles) and metal-on-polyethylene (ultra-high-molecular-weight polyethylene, UHMWPE particles) bearing surfaces in hip prostheses is a major problem in orthopedics. This study aimed to compare the influence of CoCr and UHMWPE particles on the persistence of infection. Bioluminescent Staphylococcus aureus Xen36 were injected in air pouches prepared in subcutaneous tissue of immuno-competent BALB/c mice (control), as a model for the joint space, in the absence or presence of CoCr or UHMWPE particles. Bioluminescence was monitored longitudinally up to 21 days, corrected for absorption and reflection by the particles and expressed relative to the bioluminescence found in the presence of staphylococci only. After termination, air pouch fluid and air pouch membrane were cultured and histologically analyzed. Bioluminescence was initially lower in mice exposed to UHMWPE particles with staphylococci than in mice injected with staphylococci only, possibly because UHMWPE particles initially stimulated a higher macrophage presence in murine air pouch membranes. For mice exposed to CoCr particles with staphylococci, bioluminescence was observed to be higher in two out of six animals compared to the presence of staphylococci alone. In the majority of mice, infection risk in the absence or presence of CoCr and UHMWPE particles appeared similar, assuming that the longevity of an elevated bioluminescence is indicative of a higher infection risk. However, the presence of CoCr particles yielded a higher bioluminescence in two out of six mice, possibly because the macrophage degradative function was hampered by the presence of CoCr particles. (C) 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:341347, 2012

Bacterial adhesion to and transfer between surfaces is a complicated process. With regard to the success of biomaterials implants, studies on bacterial adhesion and transfer should not be confined to biomaterials surfaces in the human body, but also encompass surfaces in the operating room, where the origin of many biomaterials related infections is found. The purpose of this study was to quantify the transfer of Staphylococcus aureus, Staphylococcus epidermidis, and Propionibacterium acnes from one operating room material to another, while accounting for surface hydrophobicity and roughness, moistness and application of friction during transfer. The tested operating room materials were gloves, broaches (orthopaedic drills), theatre gowns, and light handles. As a possible clinical intervention method to prevent transfer, it was investigated whether dipping the gloves in a chlorhexidine splash-basin affected the viability of the transferred bacteria. Transfer (moist and without friction) was demonstrated to some extent with all bacterial strains and with every material, ranging from 17% to 71%, and was influenced by the bacterial strain, moistness of the inoculum, the application of friction, and the characteristics of both the donating and the receiving surface. Dipping the glove material in 4% or 0.4% chlorhexidine solutions killed all bacteria present, regardless of whether surfaces were dried or moist and thus prevented transfer. (c) 2006 Wiley Periodicals, Inc.

The increasing gentamicin resistance among bacteria in septic joint arthroplasty has stimulated interest in adding a second antibiotic into gentamicin-loaded bone cement. A first aim of this in vitro study is to investigate whether addition of fusidic acid or clindamycin to gentamicin-loaded bone cement has an additional antimicrobial effect against a collection of 38 clinical isolates, including 16 gentamicin-resistant strains. A modified Kirby-Bauer test, involving measurement of the inhibition zone around antibiotic-loaded bone cement discs on agar plates, was used to investigate whether adding a second antibiotic has an additional antimicrobial effect. Second, a selected number of strains was used to study their survival in an interfacial gap made in the different bone cements to mimic the gap between bone and cement as existing near a prosthesis. Gentamicin loaded bone cement had an antimicrobial activity against 58% of the 38 bacterial strains included in this study, while 68% of the strains were affected by bone cement loaded with a combination of gentamicin and clindamycin. Bone cement loaded with the combination of gentamicin and fusidic acid had antimicrobial activity against 87% of the bacterial strains. In the prosthesis-related gap model, there was a clear trend toward less bacterial survival for gentamicin-loaded bone cement after adding clindamycin or fusidic acid. Addition of clindamycin or fusidic acid into gentamicin-loaded bone cement yields an additional antimicrobial effect. The combination gentamicin and fusidic acid was effective against a higher number of clinical isolates than the combination of gentamicin with clindamycin, including gentamicin-resistant strains. (c) 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.