Hironobu Koseki

Characterization of Individuals with Sacroiliac Joint Bridging in a Skeletal Population: Analysis of Degenerative Changes in Spinal Vertebrae

The aim of this study was to characterize the individuals with sacroiliac joint bridging (SIB) by analyzing the degenerative changes in their whole vertebral column and comparing them with the controls. A total of 291 modern Japanese male skeletons, with an average age at death of 60.8 years, were examined macroscopically. They were divided into two groups: individuals with SIB and those without bridging (Non-SIB). The degenerative changes in their whole vertebral column were evaluated, and marginal osteophyte scores (MOS) of the vertebral bodies and degenerative joint scores in zygapophyseal joints were calculated. SIB was recognized in 30 individuals from a total of 291 males (10.3%). The average of age at death in SIB group was significantly higher than that in Non-SIB group. The values of MOS in the thoracic spines, particularly in the anterior part of the vertebral bodies, were consecutively higher in SIB group than in Non-SIB group. Incidence of fused vertebral bodies intervertebral levels was obviously higher in SIB group than in Non-SIB group. SIB and marginal osteophyte formation in vertebral bodies could coexist in a skeletal population of men. Some systemic factors might act on these degenerative changes simultaneously both in sacroiliac joint and in vertebral column.

Effect of surface roughness of biomaterials on Staphylococcus epidermidis adhesion

BackgroundImplant-related infections are caused by adhesion of bacteria to the surface of biomaterials. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis (ATCC35984) to adhere to the surface of solid biomaterials at different levels of roughness below 30 nm Ra and investigated the minimum level of roughness required to promote bacterial adhesion on five kinds of biomaterials: oxidized zirconium-niobium alloy (Oxinium), cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4 V), commercially pure titanium (Cp-Ti) and stainless steel (SUS316L), samples of which were categorized into a fine group and a coarse group according to surface roughness. The test specimens were physically analyzed and the viable bacterial density of the adhered bacteria was quantitatively determined (n = 20).ResultsThe amount of bacteria that adhered to the biomaterials in the coarse group was higher than those in the fine group. Oxinium, Ti-6Al-4 V and SUS316L in particular demonstrated statistically significant differences between the two groups (P < 0.05). Of the materials, the Co-Cr-Mo specimens exhibited significantly lower amounts of adhered bacteria than the Ti-6Al-4 V, Cp-Ti and SUS316L specimens in the fine group. Similarly, the Co-Cr-Mo specimens in the coarse group exhibited significantly lower values than the other four materials.ConclusionsThese results suggest that minimum level of roughness affecting initial bacterial adherence activity differs according to the type of biomaterial used, and that even a surface roughness of below 30 nm Ra in Oxinium, Ti-6Al-4 V and SUS316L can promote bacterial adhesion. Relative hydrophobic Co-Cr-Mo surfaces were less susceptible to bacterial adherence.

Adherence ability of Staphylococcus epidermidis on prosthetic biomaterials: an in vitro study

Bacterial adhesion to the surface of biomaterials is an essential step in the pathogenesis of implant-related infections. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis to adhere to the surface of solid biomaterials, including oxidized zirconium-niobium alloy (Oxinium), cobalt-chromium-molybdenum alloy, titanium alloy, commercially pure titanium, and stainless steel, and performed a biomaterial-to-biomaterial comparison. The test specimens were physically analyzed to quantitatively determine the viable adherent density of the S. epidermidis strain RP62A (American Type Culture Collection [ATCC] 35984). Field emission scanning electron microscope and laser microscope examination revealed a featureless, smooth surface in all specimens (average roughness <10 nm). The amounts of S. epidermidis that adhered to the biomaterial were significantly lower for Oxinium and the cobalt-chromium-molybdenum alloy than for commercially pure titanium. These results suggest that Oxinium and cobalt-chromium-molybdenum alloy are less susceptible to bacterial adherence and are less inclined to infection than other materials of a similar degree of smoothness.

Early Staphylococcal Biofilm Formation on Solid Orthopaedic Implant Materials: In Vitro Study

Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4V), commercially pure titanium (cp-Ti) and stainless steel. A bacterial suspension of Staphylococcus epidermidis strain RP62A (ATCC35984) was added to the surface of specimens and incubated. The stained biofilms were imaged with a digital optical microscope and the biofilm coverage rate (BCR) was calculated. The total amount of biofilm was determined with the crystal violet assay and the number of viable cells in the biofilm was counted using the plate count method. The BCR of all the biomaterials rose in proportion to culture duration. After culturing for 2–4 hours, the BCR was similar for all materials. However, after culturing for 6 hours, the BCR for Co-Cr-Mo alloy was significantly lower than for Ti-6Al-4V, cp-Ti and stainless steel (P<0.05). The absorbance value determined in the crystal violet assay and the number of viable cells on Co-Cr-Mo were not significantly lower than for the other materials (P>0.05). These results suggest that surface properties, such as hydrophobicity or the low surface free energy of Co-Cr-Mo, may have some influence in inhibiting or delaying the two-dimensional expansion of biofilm on surfaces with a similar degree of smoothness.

Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins

Background: Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO2) for inhibition of infection was compared with that of stainless steel control pins in an in vivo study. Methods: Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples. Results: Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO2-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO2-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO2-coated pin group was significantly higher (71.4%) than in the control pin group (58.2%). The TiO2 was successful in decreasing infection both clinically and histomorphometrically. Conclusion: The photocatalytic bactericidal effect of TiO2 is thought to be useful for inhibiting pin site infection after external fixation.

Biofilm-Forming Staphylococcus epidermidis Expressing Vancomycin Resistance Early after Adhesion to a Metal Surface

We investigated biofilm formation and time of vancomycin (VCM) resistance expression after adhesion to a metal surface in Staphylococcus epidermidis. Biofilm-forming Staphylococcus epidermidis with a VCM MIC of 1 μg/mL was used. The bacteria were made to adhere to a stainless steel washer and treated with VCM at different times and concentrations. VCM was administered 0, 2, 4, and 8 hours after adhesion. The amount of biofilm formed was evaluated based on the biofilm coverage rates (BCRs) before and after VCM administration, bacterial viability in biofilm was visually observed using the fluorescence staining method, and the viable bacterial count in biofilm was measured. The VCM concentration required to decrease BCR significantly compared with that of VCM-untreated bacteria was 4 μg/mL, even in the 0 hr group. In the 4 and 8 hr groups, VCM could not inhibit biofilm growth even at 1,024 μg/mL. In the 8 hr group, viable bacteria remained in biofilm at a count of 104 CFU even at a high VCM concentration (1,024 μg/mL). It was suggested that biofilm-forming Staphylococcus epidermidis expresses resistance to VCM early after adhesion to a metal surface. Resistance increased over time after adhesion as the biofilm formed, and strong resistance was expressed 4–8 hours after adhesion.

Epidemiology of Kienböck’s Disease in Middle-aged and Elderly Japanese Women

Little research has been done on the prevalence of Kienböcks disease, and there is no consensus on the relationship between Kienböcks disease and negative ulnar variance. The goal of this cross-sectional study was to determine the prevalence of Kienböcks disease in middle-aged and elderly Japanese women and to clarify the relationship between Kienböcks disease and negative ulnar variance. The authors analyzed plain radiographs of both hands in women 40 years and older residing in the community to investigate the prevalence of Kienböcks disease and the relationship between Kienböcks disease and negative ulnar variance. Kienböcks disease was seen in 7 of the 572 participants. In the group with Kienböcks disease, ulnar variance did not differ significantly between affected (0.3 mm; SD, 1.5) and unaffected (0.3 mm; SD, 1.0; P=.285) sides. No significant difference was seen in ulnar variance values between the affected side in the group with Kienböcks disease and the normal group (P=.118). The number or proportion of participants with negative ulnar variance did not differ significantly between the affected side in the group with Kienböcks disease (3 of 7) and the unaffected side in the group with Kienböcks disease (1 of 7; P=.237) and between the affected side in the group with Kienböcks disease and the normal group (111 of 504; P=.189) by chi-square test. The prevalence of Kienböcks disease was 1.2% in middle-aged and elderly Japanese women. Negative ulnar variance is not a contributing factor to Kienböcks disease.

Multifocal osteonecrosis caused by traumatic pancreatitis in a child. A case report.

The main factors contributing to the development of secondary osteonecrosis are trauma, the habitual use of alcohol and steroid drugs, and medical conditions such as diabetes mellitus and hyperlipidemia1,2. Osteonecrosis is frequently seen in association with pancreatitis complicated by the alcohol factor but is rarely associated with uncomplicated pancreatitis1-4. We are aware of only one report of symptomatic osteonecrosis secondary to trauma-induced pancreatitis4. We treated a child in whom multifocal osteonecrosis developed following traumatic pancreatitis. The patients family was informed that data concerning the case would be submitted for publication and they consented. A ten-year-old girl was injured in a fall from an iron fence surrounding a swing set. She sustained a severe impact to the abdomen and was taken to our hospital. Her family history and medical history were unremarkable. On admission, the blood pressure was 120/87 mm Hg, the pulse was 82 beats/min, and the body temperature was 36.7°C. She reported intense abdominal pain and nausea. Upper abdominal muscle guarding was observed, and an abdominal computed tomography scan showed pancreatic trauma. The serum amylase level was 296 IU/L, and the white blood-cell count was 14,200/μL (14.2 × 109/L). She was diagnosed with traumatic pancreatitis. Peripancreatic drainage was performed, and conservative treatment consisting of fasting (including water), fluid management, administration of FOY (gabexate mesilate), and administration of antibiotics was initiated. Approximately ten days after the injury, polyarthralgia developed …

Effect of carbon ion implantation on the tribology of metal-on-metal bearings for artificial joints

Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses.

11. Bactericidal Activity of Photocatalytic TiO2 Excited by Low Intensity Pulsed Ultrasound (LIPUS): An In Vitro Study.

Photocatalysis with anatase-type titanium dioxide (TiO2) under ultraviolet has a well-recognized bactericidal effect. The purpose of the present study was to evaluate the photocatalytic bactericidal effects of TiO2 on Staphylococcus epidermidis (ATCC35984) caused by Low Intensity Pulsed Ultrasound (LIPUS) associated with bio-implant-related infections. The photocatalytic properties of the TiO2 films were confirmed by the degradation of an aqueous solution of methylene blue. The disks were seeded with cultured Staphylococcus epidermidis and irradiated by LIPUS. The bactericidal effect of the TiO2 films was evaluated by counting the surviving colonies. The viability of the bacteria on the photocatalytic TiO2 film coated titanium was suppressed significantly to 63% after 2 hours of LIPUS treatment (P < 0.05). The photocatalytic bactericidal effect of TiO2 under LIPUS is useful for sterilizing the contaminated and infected surfaces of metal bio-implants.