Infection after primary anatomic versus primary reverse total shoulder arthroplasty.

BACKGROUND: Deep periprosthetic infection is a serious complication after total shoulder arthroplasty (TSA) and is associated with suboptimal clinical results. This retrospective study aimed to determine whether a difference in infection rate existed after primary anatomic TSA (aTSA) and primary reverse TSA (rTSA). METHODS: A TSA database was retrospectively reviewed to identify primary TSAs performed from 2004 to 2012 and isolate cases of confirmed deep periprosthetic infection. Data collected included age, sex, preoperative diagnosis, previous nonarthroplasty operative history, implant type, and infecting organism. RESULTS: From 814 primary TSAs performed, deep periprosthetic infections were confirmed in 16 shoulders. Infections occurred in 6 aTSAs and 10 rTSAs, with no significant difference among the prosthesis types. Pathogens included Staphylococcus spp, Propionibacterium acnes, and Escherichia coli. In the subgroup of shoulders with no previous operations, no significant difference in infection rate was found among the prosthesis types. Shoulders with previous nonarthroplasty operations undergoing primary TSA exhibited a significantly higher (P = .016) infection rate compared with shoulders with no operative history. Both aTSA and rTSA performed in previously operated-on shoulders demonstrated higher infection rates compared with shoulders with no prior operative intervention. The infection rate was significantly higher (P = .016) in the rTSA group. CONCLUSIONS: There is no difference in infection rate after primary aTSA and primary rTSA in shoulders that have not undergone previous operative interventions. Infection is more likely to develop in shoulders undergoing primary rTSA that have had one or more nonarthroplasty operative procedures.

RADIOGRAPHIC ASSESSMENT OF EXTREMITY OSSEOINTEGRATION FOR THE AMPUTEE.

Osseointegration (OI) is a bone-anchoring procedure that allows the direct skeletal attachment of a prosthesis through the use of an implant. Transcutaneous OI implants are similar to subcutaneous intramedullary joint implants with some exceptions. Particularly, OI implants are inserted at the distal aspect of the femur, while intramedullary implants are inserted at the proximal aspect of the femur. In this report, an additional adaptation of the radiographic zonal analysis used for intramedullary implants, known as Gruen zones, is introduced to include OI implants of extremity prosthetics. Radiographic zonal analyses and interpretations are proposed. Gruen zones are used for intramedullary implants, which are generally inserted from the proximal aspect of the bone. OI extremity implants are inserted from the distal end of the bone. Therefore, the zonal analysis is inverted. A radiographic zonal analysis has been introduced by the Osseointegration Group of Australia (OGA). This analysis is needed specifically for the clinical evaluation of extremity OI, as significant changes to the bone and OI implant have been reported and need to be clinically described. A classification technique is necessary for establishing treatment guidelines for the extremity osseointegrated implant. The OGA Zonal analysis addresses this need by adapting a common reference standard to osseointegration of the extremity amputee.

Burch-Schneider cage fracture: a case report.

In this report, we present the case of a 64-year-old woman who sustained a Burch-Schneider cage fracture. Prior to this event, she underwent repeated acetabular reconstructions, but in the end prosthesis removal was performed as a salvage procedure. We believe that the primary cause of the fracture was metal fatigue facilitated by intraoperative re-contouring of the flange, as well as reuse of the cage. Based on this case we caution against repetitive or excessive flange bending during implantation of Burch-Schneider cages and do not recommend their reuse.

In vitro testing of gentamicin-vancomycin loaded bone cement to prevent prosthetic joint infection.

Sepsis is a greatly feared complication of total joint arthroplasty. One key question is how to prevent perioperative bacterial adherence, and therefore the potential for infectious complications. The objective of our study was to appraise the emerging capacity of staphylococcal survival on prosthetic materials and to analyze the in vitro effects of gentamicin and vancomycin loaded polymethylmethacrylate (PMMA) cement on bacterial adherence and growth. Hospital acquired staphylococcal strains were systematically inoculated on four orthopedic materials (ultrahigh molecular weight polyethylene, PMMA without antibiotic, commercially produced PMMA loaded with gentamicin, and manually mixed PMMA loaded with gentamicin and vancomycin). Staphylococci were identified using culture and biochemical tests. The inoculated material was allowed to incubate in a liquid broth growth media and subsequently prepared for scanning electron microscopy and bacterial growth quantification. Materials without antibiotics showed evidence of staphylococcal growth. PMMA loaded with only gentamicin grew methicillin-resistant Staphylococcus aureus. Gentamicin-vancomycin loaded PMMA completely inhibited any bacterial growth. Low-dose gentamicin-vancomycin loaded PMMA prevents staphylococcal colonization better than commercially manufactured PMMA loaded with gentamicin. We recommend this combination in high-risk procedures and revision surgeries requiring bone cement.

Capturing orthopaedic surgical site infection data and assessing dental recommendations with respect to total joint arthroplasty.

Greater documentation of patient history and clinical course is crucial for identifying factors that can influence surgical outcomes. The Centers for Medicare and Medicaid Services have already begun public reporting of hospital data on readmission, complication, and infection rates and will soon launch a website to make physician-specific outcomes data public. The orthopaedic community has the opportunity to lead the way in ensuring that adequate and accurate data is collected to facilitate appropriate comparisons that are based on patients' true risk of complications and the complexity of treatment. Several studies have reported a link between oral pathogens and periprosthetic infection, although it remains unclear whether organisms unique to dental tissues are also present in osteoarthritic joints and tissues affected by periprosthetic joint infection. The American Academy of Orthopaedic Surgeons and the American Dental Association are aware of these concerns and have created guidelines for antibiotic prophylaxis in patients who have undergone total hip or knee arthroplasty and require high-risk dental procedures. Because these guidelines have received considerable criticism, recommendations that are based on scientific and case-controlled clinical studies and provide effective guidance on this important subject are needed.

Plating of femoral neck fractures: when and how?

Intracapsular femoral neck fractures are common in the elderly population after a simple fall. However, femoral neck fractures in the physiologically young are less common. Regardless, femoral neck fractures can be a source of significant morbidity and mortality if not treated correctly. Multiple management strategies have been described. The decision for the ideal treatment involves careful consideration of the patient's age, activity, and medical comorbidities. Plating techniques of femoral neck fractures continue to evolve. The authors describe the current indications and plating options for the treatment of femoral neck fractures.

Surgical site infection risk factors and risk stratification.

Preoperative identification of the risk factors for surgical site infection and patient risk stratification are essential for deciding whether surgery is appropriate, educating patients on their individual risk of complications, and managing postoperative expectations. Early identification of these factors is also necessary to help guide both patient medical optimization and perioperative care planning. Several resources are currently available to track and analyze healthcare-associated infections, including the Centers for Disease Control and Prevention's National Healthcare Safety Network. In addition, the Centers for Disease Control and Prevention and the American Academy of Orthopaedic Surgeons are exploring collaborative opportunities for the codevelopment of a hip and/or knee arthroplasty national quality measure for periprosthetic joint infection.

Femoral neck fractures: current management.

Femoral neck fractures are a commonly encountered injury in orthopaedic practice and result in significant morbidity and mortality. It is essential that surgeons are able to recognize specific fracture patterns and patient characteristics that indicate the use of particular implants and methods to effectively manage these injuries. Use of the Garden and Pauwels classification systems has remained the practical mainstay of femoral neck fracture characterization that help dictate appropriate treatment. Operative options include in situ fixation, closed or open reduction and internal fixation, hemiarthroplasty, and total hip arthroplasty. Recent reports demonstrate diversity among orthopaedic surgeons in regard to the optimal treatment of femoral neck fractures and changing trends in management. The present discussion focuses on the current indications and methods for femoral neck fracture management to provide direction with respect to appropriate and effective care of these injuries.

Molecular diagnosis of prosthetic joint infection. A review of evidence.

Prosthetic joint infection (PJI) diagnosis includes several classes of verification. Among them, only a few have a stronger independent value, namely intraarticular purulence and communicating fistulas. Other diagnostic methods require careful test combinations, analysis, and interpretation. Molecular based techniques using the polymerase chain reaction (PCR) seem to be a promising PJI diagnostic modality due to its excellent sensitivity, specificity, positive predictive value, and speed. Most of the recent reviewers are in agreement that molecular diagnosis has enough potential for future application in orthopaedics even if there are only a few heterogeneous studies fully supporting this concept. Conversely, at least one study has been published with significantly worse results (sensitivity and specificity less than 0.75). The lack of supporting evidence in the published studies may be closely related to varying PCR laboratory procedures, inappropriate reference standards, and other methodological shortcomings among research centers. It is not yet justifiable to firmly include molecular methods into the present PJI diagnostic schemes. The orthopaedic community must await the results of well-organized ongoing studies before considering inclusion of molecular diagnostics as a PJI diagnostic method. The aim of this paper was to make a survey of current PJI molecular diagnostic techniques in orthopaedics.

Effect of autologous bone marrow stromal cell seeding and bone morphogenetic protein-2 delivery on ectopic bone formation in a microsphere/poly(propylene fumarate) composite.

A biodegradable microsphere/scaffold composite based on the synthetic polymer poly(propylene fumarate) (PPF) holds promise as a scaffold for cell growth and sustained delivery vehicle for growth factors for bone regeneration. The objective of the current work was to investigate the in vitro release and in vivo bone forming capacity of this microsphere/scaffold composite containing bone morphogenetic protein-2 (BMP-2) in combination with autologous bone marrow stromal cells (BMSCs) in a goat ectopic implantation model. Three composites consisting of 0, 0.08, or 8 microg BMP-2 per mg of poly(lactic-co-glycolic acid) microspheres, embedded in a porous PPF scaffold, were combined with either plasma (no cells) or culture-expanded BMSCs. PPF scaffolds impregnated with a BMP-2 solution and combined with BMSCs as well as empty PPF scaffolds were also tested. The eight different composites were implanted subcutaneously in the dorsal thoracolumbar area of goats. Incorporation of BMP-2-loaded microspheres in the PPF scaffold resulted in a more sustained in vitro release with a lower burst phase, as compared to BMP-2-impregnated scaffolds. Histological analysis after 9 weeks of implantation showed bone formation in the pores of 11/16 composites containing 8 microg/mg BMP-2-loaded microspheres with no significant difference between composites with or without BMSCs (6/8 and 5/8, respectively). Bone formation was also observed in 1/8 of the BMP-2-impregnated scaffolds. No bone formation was observed in the other conditions. Overall, this study shows the feasibility of bone induction by BMP-2 release from microspheres/scaffold composites.

A novel simplified ultra-rapid freezing technique for cryopreservation of tissue slices.

Cryopreservation offers the potential to maximize the use and availability of biological materials that have a limited supply. This study demonstrates an enhanced technique for the parallel cryopreservation of a series of liver tissue slices using a tray modeled from aluminium foil and low concentrations of a cryoprotectant. Cooling and warming rates of approximately 2000 and 3900 degrees C min(-1), respectively, were achieved as the thermal capacity of the foil-tray was significantly reduced compared to the aluminium sandwich device introduced by Day et al. [S.H. Day, D.A. Nicoll-Griffith, J.M. Silva, Cryopreservation of rat and human liver slices by rapid freezing, Cryobiology 38 (1999) 154-159]. Additionally, the two critical steps involved in the sandwich approach, i.e., clamping the plates and complete filling of the entire space between the plates with liquid, can be omitted using the foil tray. The viability of the slices was verified by measuring tetrazolium salt reduction capacity, cytosolic enzyme lactate dehydrogenase leakage, and ethoxycoumarin metabolism.