Distal femur Brucella osteomyelitis in infancy: A rare case report.

Brucella disease is an infectious disease caused by Brucella bacteria. It is transmitted through the consumption of unpasteurized dairy products and undercooked meat and penetration through the skin of individuals in contact with farm animals. A detailed medical history is of utmost importance in the diagnosis. Headache, cyclical fever, sweating, vomiting, abdominal pain, and wandering arthralgia are among the main clinical symptoms. Brucella infection is usually characterized by inflammation in the musculoskeletal system, and osteomyelitis is rarely seen. In this article, we report a case of osteomyelitis after neglected brucellosis.

RANKL-mediated osteoclast formation is required for bone loss in a murine model of Staphylococcus aureus osteomyelitis.

Staphylococcus aureus osteomyelitis leads to extensive bone destruction. Osteoclasts are bone resorbing cells that are often increased in bone infected with S. aureus. The cytokine RANKL is essential for osteoclast formation under physiological conditions but in vitro evidence suggests that inflammatory cytokines may by-pass the requirement for RANKL. The goal of this study was to determine whether RANKL-dependent osteoclast formation is essential for the bone loss that occurs in a murine model of S. aureus osteomyelitis. To this end, humanized-RANKL mice were infected by direct inoculation of S. aureus into a unicortical defect in the femur. Mice were treated with vehicle or denosumab, a human monoclonal antibody that inhibits RANKL, both before and during a 14-day infection period. The severe cortical bone destruction caused by infection was completely prevented by denosumab administration even though the bacterial burden in the femur was not affected. Osteoclasts were abundant near the inoculation site in vehicle-treated mice but absent in denosumab-treated mice. In situ hybridization demonstrated that S. aureus infection potently stimulated RANKL expression in bone marrow stromal cells. The extensive reactive bone formation that occurs in this osteomyelitis model was also reduced by denosumab administration. Lastly, there was a notable lack of osteoblasts near the infection site suggesting that the normal coupling of bone formation to bone resorption was disrupted by S. aureus infection. These results demonstrate that RANKL-mediated osteoclast formation is required for the bone loss that occurs in S. aureus infection and suggest that disruption of the coupling of bone formation to bone resorption may also contribute to bone loss in this condition.

Naringin exerts antibacterial and anti-inflammatory effects on mice with Staphylococcus aureus-induced osteomyelitis.

Osteomyelitis is an invasive bone infection that can lead to severe pain and even disability, posing a challenge for orthopedic surgery. Naringin can reduce bone-related inflammatory conditions. This study aimed to elucidate the function and mechanism of naringin in a Staphylococcus aureus-induced mouse model of osteomyelitis. Femurs of S. aureus-infected mice were collected after naringin administration and subjected to microcomputed tomography to analyze cortical bone destruction and bone loss. Bacterial growth in femurs was also assessed. Proinflammatory cytokine levels in mouse femurs were measured using enzyme-linked immunosorbent assays. Pathological changes and bone resorption were analyzed using hematoxylin and eosin staining and tartrate-resistant acid phosphatase staining, respectively. Quantitative reverse transcription polymerase chain reaction and western blot analysis were used to quantify the messenger RNA and protein expression of osteogenic differentiation-associated genes in the femurs. The viability of human bone marrow-derived stem cells (hBMSCs) was determined using cell counting kit-8. Alizarin Red S staining and alkaline phosphatase staining were performed to assess the formation of mineralization nodules and bone formation in vitro. Notch signaling-related protein levels in femur tissues and hBMSCs were assessed using western blot analysis. Experimental results revealed that naringin alleviated S. aureus-induced cortical bone destruction and bone loss in mice by increasing the bone volume/total volume ratio. Naringin suppressed S. aureus-induced bacterial growth and inflammation in femurs. Moreover, it alleviated histopathological changes, inhibited bone resorption, and increased the expression of osteogenic markers in osteomyelitic mice. It increased the viability of hBMSCs and promoted their differentiation and bone mineralization in vitro. Furthermore, naringin activated Notch signaling by upregulating the protein levels of Notch1, Jagged1, and Hes1 in the femurs of model mice and S. aureus-stimulated hBMSCs. In conclusion, naringin reduces bacterial growth, inflammation, and bone resorption while upregulating the expression of osteogenic markers in S. aureus-infected mice and hBMSCs by activating Notch signaling.

[Infected nonunion: diagnostic and therapeutic work-up]. / Infizierte Pseudarthrose: diagnostischer und therapeutischer Ablauf.

BACKGROUND: Septic nonunion is one of the major complications in fracture healing. The challenge is to identify the infection as the cause of nonunion first and then to achieve healing of the infection and the bone. OBJECTIVE: Because of the more heterogeneous appearance of an infected nonunion, the prevalence of germ detection in surgical nonunion revision is often underestimated. MATERIAL AND METHODS: In a retrospective study between 2010 and 2017, 86 patients with radiologically confirmed femoral shaft nonunion without clinical evidence and unremarkable medical history of a florid infection as the cause of nonunion, who had undergone primary single-stage surgical nonunion revision were analyzed. At least four intraoperatively obtained samples were evaluated for microbiological diagnosis. A distinction was made between tissue samples with subsequent 48­h short-term incubation and tissue samples with 14-day long-term cultivation. The finding "germ detection" was made if at least two of the samples demonstrated bacterial growth. RESULTS: In 18 of 86 patients with a nonunion preoperatively judged to be aseptic, positive bacterial evidence was obtained after short-term incubation. After long-term cultivation, positive bacterial detection was possible in 38 of 86 patients with a femoral shaft nonunion initially classified as aseptic. Regarding potential risk factors, the two groups demonstrated no relevant differences. In 29 patients, 1 pathogen was isolated from the obtained samples, whereas in the remaining 9 patients, a mixed culture with an average of 2.9 ± 0.5 different bacteria was detected. Identification revealed mainly low-virulence bacteria, most commonly Staphylococcus epidermidis. CONCLUSION: If the preoperative diagnostics including clinical, laboratory and radiological examination as well as a careful anamnesis reveal indications of a possible infectious event, the surgical nonunion revision should be performed in two stages with specimen collection before definitive nonunion revision. For microbiological diagnosis, several representative tissue samples should independently be obtained from the nonunion site and incubated for 14 days. Only in the absence of evidence of septic nonunion is a single-stage procedure suggested.

Paediatric infected femoral nonunion; mid-term results of a rare problem with a single-stage treatment and up to eleven and half years follow-up.

PURPOSE: Nonunion of femur fractures is a devastating disabling complication which is rare in children. The purpose of this study was to report the outcomes of treating infected femur nonunions in children by the Ilizarov fixator in one stage. PATIENTS AND METHODS: The study included 13 patients with unilateral infected nonunion of the femur with an average age of 9.1 years. The nonunion duration averaged 10.69 months. Ten cases were draining nonunions, and three patients had quiescent sinuses. Associated problems include shortening in all cases (mean 3.5 cm), joint stiffness (9 cases), and angular deformity (7 cases). The quiescent cases were treated by bloodless monofocal compression-distraction. Four draining cases were treated by debridement and compression with relengthening through nonunion site. The remaining six cases were treated by bifocal technique. RESULTS: The mean follow-up duration was 60.15 months. External fixation period averaged 5.3 months. Successful union was achieved in all patients. Recurrences of infection occurred in two cases including one with refracture and another one with late pathological fracture. Other complications included pin tract infections, one delayed union, two residual angular deformities, and 6 cm residual shortening in one patient. ASAMI bone results were excellent (8 patients), good (3 patients), fair (one patient), and poor (one patient). The functional results were excellent (9 cases), good (3cases), and fair (one case). CONCLUSIONS: The Ilizarov method provided a viable treatment option for treating paediatric infected femur nonunions in single stage of management with infection control in most cases and satisfactory outcomes.

Risk factors associated with recurrence of extremity osteomyelitis treated with the induced membrane technique.

INTRODUCTION: Our aim was to observe the efficacy of the induced membrane technique in the treatment of extremity osteomyelitis and to analyse the causes of infection recurrence and its risk factors. METHODS: We retrospectively analysed 424 cases of extremity osteomyelitis treated with the induced membrane technique in our department between May 2013 and June 2017. Infection recurrence time, recurrence sites and other relevant information were collected, summarized, and analysed. RESULTS: A total of 424 patients were considered as "cured" of osteomyelitis after the first stage and the induced membrane technique was performed to rebuild the bone defects. After a mean follow-up of 31.6 (16-63) months, 52 patients had recurrence of infection, including 42 tibias and 10 femurs. The recurrence rate was 12.26%. Symptoms were relieved in 16 patients after intravenous antibiotic treatment. In the remaining 36 cases (8.49%), the infection was uncontrolled by intravenous antibiotics and surgical debridement was performed. The recurrence rate of infection of the tibia (16.22%) was higher than that of the femur (8.70%). The recurrence rate of post-traumatic osteomyelitis (14.66%) was significantly higher than that of hematogenous osteomyelitis (2.41%). Patients in whom Pseudomonas aeruginosa was isolated at the first stage had a recurrence rate of 28% (7/25), which was higher than that with the other isolated bacteria. Logistic regression analysis showed that repeated operations (≥3), post-traumatic osteomyelitis, and internal fixation at the first stage were risk factors for recurrence of infection, with odds ratios (ORs) of 2.30, 5.53 and 5.28 respectively. CONCLUSIONS: The induced membrane technique is an effective method in the treatment of extremity osteomyelitis, although infection recurs in some cases. Repeated operations, post-traumatic osteomyelitis, and internal fixation at the first stage were risk factors for recurrence of infection. P. aeruginosa isolated at the first stage, tibia osteomyelitis, the presence of sinus, or flaps may also be associated with recurrence of infection.

Does the induced membrane have antibacterial properties? An experimental rat model of a chronic infected nonunion.

INTRODUCTION: The Masquelet procedure proved its efficiency in treating infected nonunion filling bony gaps up to 25 cm. Yet the use of local antibiotics is still questionable in the daily practice with lack of evidence regarding its usefulness in controlling infection. An experimental rat model is put in place to study the antibacterial properties of the induced membrane produced during the first stage of Masquelet. METHOD: Twenty-three-month-old wistar male rats are inoculated with a 0.5 mL solution of 10^8 CFU/mL MRSA over a critical fracture done on the right femur. Six weeks later, remaining 11 rats exhibiting signs of a chronic infection with a sinus tract and oozing pus along with radiological nonunion are used for a first stage Masquelet procedure. They are randomly divided into two groups with six rats having no local antibiotic in the cement mixture and five rats having 3 g of vancomycin mixed with gentamycin loaded cement. Six weeks later (twelve weeks from baseline), all eleven rats are euthanized and blood samples for C-reactive protein are withdrawn. The induced membrane is identified and resected along with bone fragments and sent for cultures and pathology. RESULTS: MRSA is isolated in the cultures of all six rats in the first group where no local antibiotic was added. Altered polymorphonuclears with abscess and pus are noted on four of six pathology samples. However in the second group where local antibiotics were added, three out of five rats exhibited eradication of MRSA (p = 0.034) and all samples did not exhibit clear infection signs on pathology. A pyo-epithelioid over a foreign body reaction is seen predominantly in this group demonstrating a regenerative process. DISCUSSION: The induced membrane does not have antimicrobial properties capable of overcoming an infected nonunion on its own. When local antibiotics were added during the first stage of the Masquelet procedure, new bone formation occurred indicating the need to control an infection in order for bone union to occur. CONCLUSION: Local antibiotics use in adjunction to extensive debridement is advisable during the first stage of a Masquelet procedure for an infected nonunion.

Osteomyelitis Caused by Bacillus Calmette-Guérin Vaccination in a Healthy Toddler.

Bacillus Calmette-Guérin (BCG) osteomyelitis in immunocompetent children is a rare complication of BCG immunization which presents with nonspecific findings and often leads to delayed diagnosis. We report a 1-year and 10-month-old male infant with complaining of knee pain and limping for 5 months. He received surgical debridement due to suspicion of malignancy but BCG osteomyelitis of the distal femur was diagnosed with the culture of the specimens which revealed to have Mycobacterium bovis-BCG strain. He was successfully treated with antituberculous therapy lasting for 1 year.

Actinomycotic osteomyelitis of a long bone in an immunocompetent adult: a case report and literature review.

BACKGROUND: Actinomycosis is a rare, chronic granulomatous disease caused by Gram-positive anaerobic bacteria that colonize the oral cavity. Cervicofacial actinomycosis is the most frequent clinical presentation of actinomycosis, but hematogenous osteomyelitis at distant sites can occur in rare instance in immunocompromised or pediatric patients, only a few cases have been reported in healthy patients. Here we described a new case of distal femur osteomyelitis caused by Actinomyces in an adult patient who was immunocompetent and had no predisposing factors. CASE PRESENTATION: A woman aged 52 years with no history of trauma presented with severe pain, swelling, and increased local heat in the proximal area of the right knee 3 weeks after she first noticed discomfort. Magnetic resonance imaging showed persistent osteomyelitis of the distal metaphysis and diaphysis of the femur with a multifocal intraosseous abscess pocket. An incision and drainage of the abscess were conducted. The tissue culture, fungus culture, acid fast bacillus (AFB) culture, AFB smear, and tuberculosis polymerase chain reaction test results were negative. A pathologic examination confirmed the presence of actinomycosis. The patient was successfully treated with intravenous penicillin G for 8 weeks followed by oral amoxicillin-clavulanate for 6 weeks with repeated surgical debridement and drainage. After a 5-year follow up, the patient had no signs of recurring infection or complications and she had full range of movement in the affected knee. CONCLUSIONS: Although rare, actinomycotic osteomyelitis can occur in healthy people. Furthermore, actinomycotic osteomyelitis is easily misdiagnosed as tuberculosis in areas with a high prevalence of tuberculosis. To detect and identify the bacteria accurately, pathologic examination should be performed as well as culture tests, because the probability for culture confirmation of actinomycosis is quite low. The initial treatment is vital to a successful outcome without ostectomy or amputation.

Bacterial DNA is associated with tunnel widening in failed ACL reconstructions.

PURPOSE: To determine if tunnel widening, defined as change in maximal tunnel diameter from the time of initial bone tunnel drilling to revision surgery is associated with bacterial deoxyribonucleic acid (DNA) presence and concentration in torn graft tissue from failed anterior cruciate ligament reconstructions (ACLRs). METHODS: Thirty-four consecutive revision ACLRs were included (mean age 27.3 years SD 10.9; median time to failure 4.9 years range 105 days-20 years). Graft selection of the failed reconstruction was 68% autograft, 26% allograft, and 6% autograft/allograft hybrid with a mean drilled tunnel diameter of 8.4 mm SD 0.8. Maximal tunnel diameters prior to revision were measured on pre-operative three-dimensional imaging and compared to drilled tunnel diameters at the time of the previous reconstruction. Tissue biopsies of the failed graft were obtained from tibial, femoral, and intraarticular segments. Sterile water left open to air during revision ACLRs and tissue from primary ACLRs were used as negative controls. Clinical cultures were obtained on all revision ACLRs and PCR with universal bacterial primer on all cases and negative controls. Fluorescence microscopy was used to confirm the presence and location of biofilms in two patients with retrieved torn graft tissue and fixation material. Amount of tunnel widening was compared to bacterial DNA presence as well as bacterial DNA concentration via Welch ANOVA. RESULTS: Bacterial DNA was present in 29/34 (85%) revision ACLRs, 1/5 (20%) of primary ACLR controls and 0/3 (0%) sterile water controls. Cultures were positive (coagulase negative Staphylococcus sp.) in one case, which also had the greatest degree of tunnel widening. Femoral widening was greater in cases with detectable bacterial DNA (mean widening 2.6 mm SD 3.0) versus without (mean 0.3 mm SD 0.6) (p = 0.003) but was unaffected by bacterial DNA concentration (p = 0.44). Tibial widening was not associated with the presence of bacterial DNA (n.s.); however, higher bacterial DNA concentrations were observed in cases with tibial widening ≥ 3.0 mm (median 2.47 ng bacterial DNA/µg total DNA) versus widening < 3.0 mm (median 0.97 ng bacterial DNA/µg total DNA) (p = 0.046). Tunnel widening was not associated with time to failure, graft selection, or number of prior surgeries (n.s., all comparisons). Fluorescence microscopy confirmed the presence of biofilms on ruptured tendon graft as well as fixation material in 2/2 cases. CONCLUSION: Bacterial DNA is commonly encountered on failed ACLR grafts and can form biofilms. Bacterial DNA does not cause clinically apparent infection symptoms but is associated with tunnel widening. Further research is needed to determine whether graft decontamination protocols can reduce graft bacterial colonization rates, ACLR tunnel widening or ACLR failure risk. LEVEL OF EVIDENCE: Therapeutic III.

Dual-functional 3D-printed composite scaffold for inhibiting bacterial infection and promoting bone regeneration in infected bone defect models.

Infection is one of the pivotal causes of nonunion in large bone defect after trauma or tumor resection. Three-dimensional (3D) composite scaffold with multifunctional-therapeutic properties offer many advantages over allogenic or xenogenic bone grafting for the restoration of challenging infected bone defects. In the previous study, we demonstrated that quaternized chitosan (HACC)-grafted polylactide-co-glycolide (PLGA)/hydroxyapatite (HA) scaffold (PLGA/HA/HACC) via 3D-printing technique exhibited significantly improved antimicrobial and osteoconductive property in vitro, together with good biocompatibility in vivo. Hence, the present study further investigated whether such an innovative bone substitute could effectively inhibit the bacterial biofilm formation and promote bone regeneration in vivo. To evaluate the bone repairing effects of the 3D-printed scaffolds on infected cortical and cancellous bone defects scenarios, eighty female Sprague Dawley rats and thirty-six female New Zealand white rabbits were used to establish infected femoral shaft defect and condyle defect model, respectively. X-ray, micro-CT, microbiological and histopathological analyses were used to assess the anti-infection and bone repairing potential of the dual-functional porous scaffolds. We observed that HACC-grafted PLGA/HA scaffolds exhibited significantly enhanced anti-infection and bone regeneration capability in different infected bone defect models. In addition, the degradation rate of the scaffolds appeared to be closely related to the progress of infection, influencing the bone repairing potential of the scaffolds in infected bone defects models. In general, this investigation is of great significance as it demonstrates promising applications of the 3D-printed dual-functional PLGA/HA/HACC scaffold for repairing different types of bone defect under infection. STATEMENT OF SIGNIFICANCE: Currently, it is clinically urgent to exploit bone substitutes with potential of bacterial inhibition and bone regeneration. However, bone scaffolds with relatively low risks of bacterial resistance and tissue toxicity used for combating infected bone defects remain to be developed. We have reported that quaternized chitosan (HACC)-grafted 3D-printed PLGA/HA composite scaffold had enhanced in vitro antimicrobial and osteoconductive property, and well cytocompatibility in our published study. This continuing study further confirmed that HACC-grafted PLGA/HA scaffolds exhibited significantly enhanced anti-infection and bone regeneration efficacy in both cortical bone defect in rat and cancellous bone defect in rabbit under infection. Meanwhile, we also found that the degradation rate of the scaffolds seemed to be closely related to the progress of infection, influencing the bone repairing potential of the scaffolds in infected bone defects models. In conclusion, this study provides significant opportunities to develop a 3D-printed bone scaffold with dual functions used for infected bone defects in future plastic and orthopaedic surgery.

The effect of storage delay and storage temperature on orthopaedic surgical samples contaminated by Staphylococcus Epidermidis.

BACKGROUND: Prosthetic Joint Infection (PJI) is a rare but devastating complications with high morbitity and mortality. The identification of the causal microorganism remains crucial and determines therapeutic strategies and success. Microbiology cultures remain the common method to diagnose PJI. Unfortunately, 14% of intra-articular punctures remain negative after culture. The microorganisms are best detected by inoculation of microbiology samples in blood culture bottles (Bactec), or after sonication of the implant and polymerase chain reaction (PCR). The identification of the causal microorganism remains crucial and determines therapeutic success. OBJECTIVES: This study was conducted to assess the effect of culture lead time and sample storage temperature on the detection of the pathogen. METHODS: We obtained bone fragments from femoral heads during primary arthroplasty. Bone fragments were contaminated with a strain of Staphylococcus epidermidis. Four set-ups with different combinations of storage delay and storage temperature were tested. RESULTS: Our study shows the need to cultivate as soon as possible and optimally within 2h after the completion of sampling. Temporary storage in a refrigerator at 4°C also appears to have a positive influence on bacterial viability. At present, these conclusions concern only the Staphylococcus Epidermidis. Others studies are requested to generalize this conclusion to other bacteria.

Case of femoral pseudarthrosis due to Scedosporium apiospermum in an immunocompetent patient with successful conservative treatment and review of literature.

Scedosporium apiospermum is a ubiquitous filamentous fungus, commonly found in soil, sewage and polluted waters. It is rarely pathogenic but can cause a broad spectrum of clinical diseases, which can be localised or disseminate to distant organs. The disseminated form of the disease is mostly seen among immunocompromised patients. However, some rare cases of disseminated disease have been reported in immunocompetent individuals. Treatment of these infections is challenging because of their natural resistance to many antifungal agents. Here, we report the case of a 57-year-old immunocompetent patient diagnosed with femoral pseudarthrosis due to S. apiospermum, despite having no obvious clinical sign of infection. Previously, the patient had undergone four iterative femoral surgeries following a road traffic accident which occurred 20 years before. During its last surgery for pseudarthrosis, no clinical or biological signs of infection were present. Per operative samples tested positive for S. apiospermum. The patient was successfully treated with oral voriconazole during 6 months with an excellent tolerance. We also provide a review of literature on bone and joint infections due to Scedosporium spp. (S. apiospermum, Scedosporium boydii and Scedosporium aurantiacum), discussing the evolution of their management and outcome which seems to improve since the use of voriconazole.

Clinical and diagnostic features of trochanteric tuberculosis.

Trochanteric tuberculosis is a very rare localization of musculo-skeletal tuberculosis. The diagnosis is difficult and is often made in a late stage. The authors describe five cases of trochanteric tuberculosis. The mean age of patients was 46.6 years. Time to diagnosis was long (7.6 months on average). The tuberculosis was plurifocal in all cases. Diagnosis was based on positive Lowenstein culture in one case, on the presence of caseum granuloma in one case and through a pathognommonic manifestation in one case. For the remaining two cases, diagnosis was established on clinical and paraclinical arguments. The patients recovered after medical treatment alone.

Spontaneous fracture of the femur due to osteomyelitis caused by the Streptococcus anginosus group.

A 57-year-old man was admitted because of pain in the right upper leg due to an osteolytic lesion of the femoral bone which was complicated by a spontaneous fracture. At first a malignancy was suspected. However, blood and bone cultures revealed the Streptococcus anginosus group. A diagnosis of acute osteomyelitis was made. In spite of extensive antibiotic and surgical treatment the patient developed severe septic shock with multiple organ failure and died. In the case of a pathological fracture, one should consider the broad differential diagnosis, including osteomyelitis, which should lead to a laboratory work-up and imaging studies. When bone biopsy for histological analysis is necessary, a microbiological culture to look for osteomyelitis should always be performed.

Covalent Immobilization of Enoxacin onto Titanium Implant Surfaces for Inhibiting Multiple Bacterial Species Infection and In Vivo Methicillin-Resistant Staphylococcus aureus Infection Prophylaxis.

Infection is one of the most important causes of titanium implant failure in vivo A developing prophylactic method involves the immobilization of antibiotics, especially vancomycin, onto the surface of the titanium implant. However, these methods have a limited effect in curbing multiple bacterial infections due to antibiotic specificity. In the current study, enoxacin was covalently bound to an amine-functionalized Ti surface by use of a polyethylene glycol (PEG) spacer, and the bactericidal effectiveness was investigated in vitro and in vivo The titanium surface was amine functionalized with 3-aminopropyltriethoxysilane (APTES), through which PEG spacer molecules were covalently immobilized onto the titanium, and then the enoxacin was covalently bound to the PEG, which was confirmed by X-ray photoelectron spectrometry (XPS). A spread plate assay, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM) were used to characterize the antimicrobial activity. For the in vivo study, Ti implants were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and implanted into the femoral medullary cavity of rats. The degree of infection was assessed by radiography, micro-computed tomography, and determination of the counts of adherent bacteria 3 weeks after surgery. Our data demonstrate that the enoxacin-modified PEGylated Ti surface effectively prevented bacterial colonization without compromising cell viability, adhesion, or proliferation in vitro Furthermore, it prevented MRSA infection of the Ti implants in vivo Taken together, our results demonstrate that the use of enoxacin-modified Ti is a potential approach to the alleviation of infections of Ti implants by multiple bacterial species.

Delayed Propionibacterium acnes surgical site infections occur only in the presence of an implant.

Whether Propionibacterium acnes (P. acnes) causes surgical-site infections (SSI) after orthopedic surgery is controversial. We previously reported that we frequently find P. acnes in intraoperative specimens, yet none of the patients have clinically apparent infections. Here, we tracked P. acnes for 6 months in a mouse osteomyelitis model. We inoculated P. acnes with an implant into the mouse femur in the implant group; the control group was treated with the bacteria but no implant. We then observed over a 6-month period using optical imaging system. During the first 2 weeks, bacterial signals were detected in the femur in the both groups. The bacterial signal completely disappeared in the control group within 28 days. Interestingly, in the implant group, bacterial signals were still present 6 months after inoculation. Histological and scanning electron-microscope analyses confirmed that P. acnes was absent from the control group 6 months after inoculation, but in the implant group, the bacteria had survived in a biofilm around the implant. PCR analysis also identified P. acnes in the purulent effusion from the infected femurs in the implant group. To our knowledge, this is the first report showing that P. acnes causes SSI only in the presence of an implant.

Gamma Radiation Sterilization Reduces the High-cycle Fatigue Life of Allograft Bone.

BACKGROUND: Sterilization by gamma radiation impairs the mechanical properties of bone allografts. Previous work related to radiation-induced embrittlement of bone tissue has been limited mostly to monotonic testing which does not necessarily predict the high-cycle fatigue life of allografts in vivo. QUESTIONS/PURPOSES: We designed a custom rotating-bending fatigue device to answer the following questions: (1) Does gamma radiation sterilization affect the high-cycle fatigue behavior of cortical bone; and (2) how does the fatigue life change with cyclic stress level? METHODS: The high-cycle fatigue behavior of human cortical bone specimens was examined at stress levels related to physiologic levels using a custom-designed rotating-bending fatigue device. Test specimens were distributed among two treatment groups (n = 6/group); control and irradiated. Samples were tested until failure at stress levels of 25, 35, and 45 MPa. RESULTS: At 25 MPa, 83% of control samples survived 30 million cycles (run-out) whereas 83% of irradiated samples survived only 0.5 million cycles. At 35 MPa, irradiated samples showed an approximately 19-fold reduction in fatigue life compared with control samples (12.2 × 10(6) ± 12.3 × 10(6) versus 6.38 × 10(5) ± 6.81 × 10(5); p = 0.046), and in the case of 45 MPa, this reduction was approximately 17.5-fold (7.31 × 10(5) ± 6.39 × 10(5) versus 4.17 × 10(4) ± 1.91 × 10(4); p = 0.025). Equations to estimate high-cycle fatigue life of irradiated and control cortical bone allograft at a certain stress level were derived. CONCLUSIONS: Gamma radiation sterilization severely impairs the high cycle fatigue life of structural allograft bone tissues, more so than the decline that has been reported for monotonic mechanical properties. Therefore, clinicians need to be conservative in the expectation of the fatigue life of structural allograft bone tissues. Methods to preserve the fatigue strength of nonirradiated allograft bone tissue are needed. CLINICAL RELEVANCE: As opposed to what monotonic tests might suggest, the cyclic fatigue life of radiation-sterilized structural allografts is likely severely compromised relative to the nonirradiated condition and therefore should be taken into consideration. Methods to reduce the effect of irradiation or to recover structural allograft bone tissue fatigue strength are important to pursue.

Cryptococcal infection of the femoral bone similar with pathologic features of vascular tumors: a case report and review of literature.

A rare case is presented of a 62-year-old man with primary isolated cryptococcal femoral osteomyelitis. Magnetic resonance imaging (MRI) revealed osteolytic destruction of his left femur. Biopsy was performed firstly. Under microscope, the lesion was compose of numerous large mononuclear cells, scattered multinucleated giant cells, a few lymphocytes and neutrophils, necrosis with serious artificial deformation. By immunohistochemistry (IHC), only CD31 and CD68 were positive, while CK, CK8/18, EMA, P63, CK7, CK20, PSAP, PSA, CD34 negative. It was considered a low grade vascularsarcoma, but not confirmed. Then the operation was done. Surgical specimen showed a lot of red-sphere materials in most cells cytoplasm. The Gomorra methenamine silver staining and PAS revealed the mucopolysaccharide-containing capsule of the Cryptococcus. Laboratory culture of lesion liquid grew a kind of yeast at 37°C. Cryptococcal femoral osteomyelitis was diagnosed at last. The patient is good now after the thorough debridement and anti-fungal treatment.

Subacute osteomyelitis of the femur due to Fusobacterium nucleatum in a 7-year-old boy.

Subacute hematogenous osteomyelitis is an insidious infection, which commonly has a delayed diagnosis. We describe the case of a 7-year-old boy with subacute osteomyelitis, which was initially considered to be a bone tumor. Infection should be considered in all cases of bone pain, especially in children, even in the absence of typical systemic features of inflammation.