This report describes a case of mechanically assisted crevice corrosion and secondary adverse local tissue reaction in a patient following a total hip arthroplasty, utilizing a modular neck (bi-modular) femoral component. Radiographic evaluation demonstrated a well-positioned, stable, cementless arthroplasty. Upon further evaluation, the patient had elevated serum cobalt and chromium levels, and magnetic resonance imaging demonstrated a periprosthetic pseudotumor. Corrosion of both the neck-stem and head-neck junctions was suspected. At the time of surgery, the neck-body junction was pristine; however, the head-neck junction of the implant demonstrated severe corrosive wear, a problem that has been reported only once previously with this particular bi-modular implant. This serves as a reminder that any modular junction may be susceptible to corrosion and not all bi-modular designs behave similarly.
Seroma formation in a knee arthroplasty surgery is a rare complication. When seromas occur, they act as a nidus for bacterial growth and create an optimal environment for surgical site infections. In this case report, a 52-year-old woman presented with a seroma after multiple revision operations on the left knee. Owing to multiple failures of standard irrigation and drainage procedures to resolve the seroma, an orthoplastic colleague was consulted. Over five-and-a-half months, the patient underwent multiple procedures that failed to treat the seroma. However, in a final exploratory procedure, 3000 mg of urinary bladder matrix and negative pressure wound vacuum were placed. Seven months after the intervention, the patient had complete resolution.
OBJECTIVE:To use finite element analysis (FEA) for evaluation of the biomechanics of plates used for the repair of mandibular fractures. METHODS:Computerized tomography (CT) data for the normal human mandible were obtained from a patient's craniofacial region imaged in the axial plane at 1.5 mm intervals.These data were then imported into Mimics 7.3 (Materialise, Glen Burnie, MD, USA) in image format. Masks for cortical bone, cancellous bone and dentin were designated separately with tools available in Mimics.The masks for each entity were approximated by IGES curves and imported into ANSYS 8.0 (Ansys Inc., Canonsburg, PA, USA).The volumes created for these entities were meshed using tetrahedral shaped solid elements. Each entity was modeled as elastic and isotropic. Data for ultimate tensile strength, Poisson's ratio and Young's modulus for each entity were taken from information on the material properties of the mandible available in the literature.An artificial gap was created in the symphysis of the mandible to mimic a fracture. Plates were created and shaped to the contour of the mandible overlying the region of the fracture using Solid Works 2001 Plus (Solid Works Corporation, Concord, MA, USA).The plates were then exported in IGES format into the pre-existing model of the mandible in ANSYS. Four plate configurations were compared for fitness of use ( Fig. 1): ladder; large/small band; small bands; and large band. Unicortical and bicortical screws were simulated as solid cylinders.The force of the unilateral molar clench used for FEA was 150 N (Fig. 2). RESULTS:All bone-screw-plate constructs showed peak Von Mises stress surrounding the superior border of the screw proximal to the fracture on the side ipsilateral to the clench. Stresses did not exceed the ultimate stress for bone (120 MPa) in the region surrounding the screws on the anterior cortical surface. Stresses along the screw decayed towards the cancellous bone along the screw-bone interface.All configurations tested showed little or no stress in cancellous bone or lingual cortex.All configurations showed maximal tensile stress on the lower border of the mandible and maximal compression on the superior border. CONCLUSION:On the basis of FEA, we conclude that all plate configurations tested are suitable to repair mandibular fractures. Unicortical screw fixation is adequate for fixation.Time required for contouring and fixation along with other ancillary features should be the principal criteria in selection of specific types of plates for mandibular fracture reduction.
Introduction: Differentiating septic arthritis from aseptic arthritis (AA) of the knee is difficult without arthrocentesis. Although procalcitonin (PCT) has shown diagnostic value in identifying bacterial infections, it has not been established as a reliable marker for identifying septic arthritis (SA). Recent studies have shown promise in the use of PCT as a useful systemic marker for identifying septic arthritis versus AA. This observational retrospective review compares PCT with routine inflammatory markers as a tool for differentiating septic arthritis versus AA in patients with acute, atraumatic knee pain. Methods: Fifty-three consecutive patients (24 SA, 29 AA) were retrospectively reviewed at one institution with concern for SA. SA was diagnosed based on a physical examination, laboratory markers, and arthrocentesis. Laboratory indices were compared between the septic arthritis and AA groups. Data analysis was conducted to define sensitivity and specificity. Receiver operator characteristic curve analysis and regression were conducted to determine the best marker for acute SA of the knee. Results: Using multiple logistic regression, bacteremia (OR 6.75 ± 5.75) was determined to be the greatest predictor of SA. On linear regression, concomitant bacteremia (coef 3.07 ± 0.87), SA (coef 2.18 ± 0.70), and the presence of pseudogout crystals (coef 1.80 ± 0.83) on microscopy predicted an increase in PCT. Using a PCT cutoff of 0.25 ng/mL yields a sensitivity of 91.7% and specificity of 55.2% for predicting SA; however, the ideal cutoff in our series was 0.32 ng/mL with a sensitivity of 79.2% and specificity of 72.4%. PCT was superior to the white blood cell count, erythrocyte sedimentation rate, and C-reactive protein in the area under the receiver-operating characteristic curve analysis. Discussion: Procalcitonin seems to be the most sensitive and specific systemic marker in differentiating septic from AA.
Lemierre Syndrome (LS) is a rare, potentially life-threatening infection that typically develops from invasion of bacteria through pharyngeal mucosal tissue, followed by septic thrombophlebitis, most often involving the internal jugular vein.1 The primary complication of concern is the formation of septic emboli to the lungs or other organs. Fusobacterium necrophorum is the most common causative pathogen of LS.1 Typically, patients present with high fevers, sore throat, neck pain, and pulmonary symptoms. Though LS diagnosis is often overlooked because the initial manifestations may be subtle and non-specific, prompt diagnosis and treatment with antibiotics are imperative to prevent disease progression and promote quick recovery.
with spinal anesthesia, and whether this leads to falsely decreased temperature readings in the OR setting. In our hospital, the anesthesia team will sometimes obtain oral temperatures in patients with laryngeal mask airway or spinal anesthesia and enter these in the EHR, and these are often inaccurate (often a degree or more lower) when used as a proxy for core temperatures.We too found cooling during transition from the preoperative holding area to the OR and from OR to postoperative recovery area (Fig. 1) and agree with the other conclusions outlined in the manuscript. However, using a single validated temperature gauge throughout the OR experience in our smaller, prospective sample, we found no hypothermia. Ambient room temperature was 19 C during our study.In conclusion, I am concerned that use of a retrospective analysis of patient temperatures from the EHR, and comparing core temperatures obtained with different measurement devices, has led to the incorrect conclusion that hypothermia is rampant in total joint surgery. Furthermore, the investigators' solution of increasing the ambient temperature the OR may not be warranted or advisable and may have unintended consequences. Further research in this area should be considered before making this recommendation universal.
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