[A hockey player with displacement of the wrist]. / Een hockeyer met een standsafwijking van de pols.

A 17-year-old boy had a painful left wrist after he fell while playing hockey. Examination showed volar displacement of the distal part of the ulna; the ulnar styloid prominence was absent. X-rays showed isolated volar displacement of the distal ulna. The diagnosis 'distal radio-ulnar joint dislocation' was made. Treatment consisted of K-wire fixation and an upper arm cast. He reached functional recovery.

In vivo release of the antimicrobial peptide hLF1-11 from calcium phosphate cement.

We studied the release of human lactoferrin 1-11 (hLF1-11), a potent antimicrobial peptide, in an animal model. Calcium phosphate cement with 50 mg/g hLF1-11 was injected into the femoral canal of 12 rabbits. One, 3, and 7 days later, four animals were terminated, and the femora excised. Sections of bone and cement were removed for histological analysis. We used liquid chromatography-mass spectrometry/mass spectrometry for semiquantitative determination of the hLF1-11 concentration. Blood samples were drawn for leukocyte count and differentiation to identify a potential immunomodulating effect of hLF1-11. After an initial burst release, the hLF1-11 concentration in cement and bone decreased steadily. This in vivo release profile is consistent with earlier in vitro studies. Tissue ingrowth into the cement, without signs of inflammation or necrosis, was observed. Leukocytosis or a shift in leukocyte differentiation did not occur. The carrier released over 99% of the hLF1-11, resulting in peak concentrations at the cement-bone interface. This indicates that hLF1-11 could become a valuable prophylactic agent in osteomyelitis treatment.

Antimicrobial peptides: review of their application in musculoskeletal infections.

Antimicrobial resistance is expected to increase the burden of osteomyelitis drastically. The rise in resistant bacterial strains is driving researchers to find new treatment options. As a potential new antibiotic class, antimicrobial peptides (AMPs) combine several attractive intrinsic properties. Their minimal propensity for inducing antimicrobial resistance could be of particular clinical significance. AMPs act as an essential part of the innate immune system and have been identified in virtually all forms of life. These short, positively charged peptides have a combined pore-forming and intracellular killing effect on a broad range of microorganisms. Their reported spectrum of action includes resistant bacterial strains, viruses, and fungi. Moreover, immunomodulating, antitumoric, and angiogenic mechanisms have been reported. We have designed degradable and nondegradable drug-release systems for local treatment with AMPs. In animal models of osteomyelitis, these systems reduced bone infection caused by both resistant and nonresistant strains. The systemic application of several peptides for experimental detection and treatment of bone and soft-tissue infection is also discussed in this review. Radioactive-labeled peptides have accurately discriminated sterile inflammation from active infection in imaging studies. Successful preclinical studies of AMPs indicate that clinical evaluation of these powerful antibiotic agents is in order.

In vitro gentamicin release from commercially available calcium-phosphate bone substitutes influence of carrier type on duration of the release profile.

BACKGROUND: Polymethyl-methacrylate (PMMA) beads releasing antibiotics are used extensively to treat osteomyelitis, but require surgical removal afterwards because they do not degrade. METHODS: As an alternative option, this report compares the in vitro gentamicin release profile from clinically used, biodegradable carrier-materials: six injectable cements and six granule-types. Cement cylinders and coated granules containing 3% gentamicin were submerged in dH2O and placed in a 48-sample parallel drug-release system. At regular intervals (30, 90, 180 min. and then every 24 h, for 21 days), the release fluid was exchanged and the gentamicin concentration was measured. The activity of released gentamicin was tested on Staphylococcus aureus. RESULTS: All combinations showed initial burst-release of active gentamicin, two cements had continuous-release (17 days). The relative release of all cements (36-85%) and granules (30-62%) was higher than previously reported for injectable PMMA-cements (up to 17%) and comparable to other biodegradable carriers. From the cements residual gentamicin could be extracted, whereas the granules released all gentamicin that had adhered to the surface. CONCLUSION: The high release achieved shows great promise for clinical application of these biodegradable drug-carriers. Using the appropriate combination, the required release profile (burst or sustained) may be achieved.

Histatin and lactoferrin derived peptides: antimicrobial properties and effects on mammalian cells.

In order to analyze the clinical potential of two antimicrobial peptides, human lactoferrin 1-11 (hLF1-11) and synthetic histatin analogue Dhvar-5, we measured the killing effect on bacteria, and the potential toxicity on erythrocytes and bone cells. The antimicrobial activity was determined in a killing assay on six strains, including methicillin resistant Staphylococcus Aureus. The effect on human erythrocytes and MC3T3 mouse bone cells was measured with a hemolysis assay and a viability assay, respectively. Both hLF1-11 and Dhvar-5 dose-dependently killed all bacterial strains, starting at concentrations of 6 microg/mL. hLF1-11 had no effect on mammalian cells at concentrations up to 400 microg/mL, but Dhvar-5 induced significant hemolysis (37% at 200 microg/mL) and bone cell death (70% at 400 microg/mL). This indicates that both peptides are able to kill various resistant and non-resistant bacteria, but Dhvar-5 may exert a cytotoxic effect on host cells at higher concentrations.

Comparable efficacies of the antimicrobial peptide human lactoferrin 1-11 and gentamicin in a chronic methicillin-resistant Staphylococcus aureus osteomyelitis model.

The therapeutic efficacy of an antimicrobial peptide, human lactoferrin 1-11 (hLF1-11), was investigated in a model of chronic methicillin-resistant Staphylococcus aureus (MRSA) (gentamicin susceptible) osteomyelitis in rabbits. We incorporated 50 mg hLF1-11/g or 50 mg gentamicin/g cement powder into a calcium phosphate bone cement (Ca-P) and injected it into the debrided tibial cavity, creating a local drug delivery system. The efficacy of hLF1-11 and gentamicin was compared to that of a sham-treated control (plain bone cement) (n=6) and no treatment (infected only) (n=5). The results were evaluated by microbiology, radiology, and histology. MRSA was recovered from all tibias in both control groups (n=11). On the other hand, hLF1-11 and gentamicin significantly reduced the bacterial load. Furthermore, no growth of bacteria was detected in five out of eight and six out of eight specimens of the hLF1-11- and gentamicin-treated groups, respectively. These results were confirmed by a significant reduction of the histological disease severity score by hLF1-11 and gentamicin compared to both control groups. The hLF1-11-treated group also had a significantly lower radiological score compared to the gentamicin-treated group. This study demonstrates the efficacy of hLF1-11 incorporated into Ca-P bone cement as a possible therapeutic strategy for the treatment of osteomyelitis, showing efficacy comparable to that of gentamicin. Therefore, the results of this study warrant further preclinical investigations into the possibilities of using hLF1-11 for the treatment of osteomyelitis.

Biodegradable X-ray markers of controlled radio-opacity. Temporary position measurements in bone.

In order to analyze X-ray markers for potential use in biodegradable implants or radiostereogrammatic analysis (RSA), we combined iopromide contrast fluid with biodegradable calcium phosphate cement. The radio-opacity of 10 x 10 mm markers containing different iodine concentrations (0, 120, 240, 360 and 720 mg per gram cement) was compared to an aluminium wedge of increasing (1-10 mm) thickness. The addition of iopromide increased the radio-opacity in a dose-dependent manner, which was comparable to 9-mm aluminium at concentrations of 240-720 mg/g. Radiographs of markers placed in explanted rabbit and in human femora were made to investigate the clinical accuracy for position determination. Markers of 1 x 1 mm (120 mg/g) were clearly discernable in all femora, and could be used to adequately measure distances of 5-45 mm (accuracy 0.10-2.19 mm). These markers might be embedded in biodegradable implants or used as temporary markers in the bone to analyze postoperative position on radiographs.

In vivo comparison of Dhvar-5 and gentamicin in an MRSA osteomyelitis prevention model.

OBJECTIVES: The continued rise in drug-resistant pathogens has led to global research efforts into new antimicrobial agents. A promising class of new agents are the antimicrobial peptides. The aim of the study was to investigate the efficacy of the antimicrobial peptide Dhvar-5 in a prophylactic, methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis model. METHODS: Dhvar-5 (12 mg or 24 mg/rabbit) was incorporated into polymethyl methacrylate (PMMA) beads as a local drug delivery system. For comparison, plain beads (control) and beads containing gentamicin as a sulphate (10 mg or 24 mg per rabbit) were also prepared. The beads were inserted into the inoculated femoral cavity of 36 rabbits, and 1 week later they were killed. The presence and severity of MRSA osteomyelitis was assessed by culture and histology. RESULTS: Both the 24 mg Dhvar-5 beads and the 24 mg gentamicin sulphate beads significantly reduced the bacterial load of the inoculated femora compared with the control chain. Although a 24 mg Dhvar-5 dose inhibited MRSA growth, it did not completely sterilize the femora. Sterilization occurred only in some of the gentamicin-treated specimens. CONCLUSION: We conclude that both the gentamicin beads and the Dhvar-5 beads were only partially effective at preventing MRSA infection in this model.

Osteomyelitis prevention in rabbits using antimicrobial peptide hLF1-11- or gentamicin-containing calcium phosphate cement.

OBJECTIVES: The efficacy of prophylactic treatment with human lactoferrin 1-11 (hLF1-11), a broad-spectrum antimicrobial peptide, was studied in a rabbit model of femur infection. METHODS: Calcium phosphate cement with 50 mg/g hLF1-11 or gentamicin was injected into the femoral canal, after inoculation with Staphylococcus aureus. Three weeks later, slices of the proximal femora were sawn for quantitative bacterial culture and histology. RESULTS: Treatment with hLF1-11 (P<0.038) or gentamicin (P<0.008) caused a reduction of cfu compared with the untreated control rabbits. The number of sterile cultures was higher in hLF1-11- (3/7) and gentamicin- (5/6) treated animals than in controls (1/7). Radiological and histological analysis showed early bone ingrowth into the cement cracks, and only moderate pathological changes in rabbits with positive cultures. CONCLUSIONS: Local prophylaxis with hLF1-11 effectively reduced development of osteomyelitis in a rabbit model, but gentamicin resulted in a larger number of sterile femora.

Continuous-release or burst-release of the antimicrobial peptide human lactoferrin 1-11 (hLF1-11) from calcium phosphate bone substitutes.

OBJECTIVES: In order to identify possible drug delivery systems against resistant bone infection, we determined the release of the antimicrobial peptide (AMP) human lactoferrin 1-11 (hLF1-11) from commercially available bone substitutes. METHODS: We combined six calcium phosphate cements and six granule-types with 5 mg/g hLF1-11 and measured its availability and release in vitro from cements (7 days) and granules (3 days). The integrity and antimicrobial activity of the hLF1-11 that was released during the first 24 h were measured, using mass spectrometry, and a killing assay on methicillin-resistant Staphylococcus aureus (MRSA). RESULTS: Most of the cements showed burst release followed by low-level continuous release, whereas the coated granules showed high burst release for 24 h. After release the peptide was active (in nine of 12 materials) and intact. CONCLUSIONS: Different release profiles may be obtained by choosing the appropriate carrier, which supports the feasibility of biodegradable carriers releasing AMPs against resistant infections.