Catastrophic Failure of a MiniHip Femoral Stem: A Case Report.

CASE: The patient is a 63-year-old man who previously underwent a right total hip arthroplasty with the Corin MiniHip femoral stem. Within the first few months postoperatively, he had a fall that resulted in subsidence of his femoral prosthesis and subsequent revision shortly thereafter with a 10-mm skirted cobalt chrome femoral head. Eight years after the index procedure, the patient heard a crack and then collapsed while putting on bicycle shorts. Workup demonstrated a fracture of the stem at the base of the neck of the implant. Femoral stem revision with a diaphyseal engaging, modular implant, and dual mobility hip construct was performed. CONCLUSION: Atraumatic catastrophic failure of the femoral stem implant may be associated with long skirted femoral heads that create excessive bending moments on the stem and revision surgery.

Asymptomatic spread of huanglongbing and implications for disease control.

Huanglongbing (HLB) is a bacterial infection of citrus trees transmitted by the Asian citrus psyllid Diaphorina citri. Mitigation of HLB has focused on spraying of insecticides to reduce the psyllid population and removal of trees when they first show symptoms of the disease. These interventions have been only marginally effective, because symptoms of HLB do not appear on leaves for months to years after initial infection. Limited knowledge about disease spread during the asymptomatic phase is exemplified by the heretofore unknown length of time from initial infection of newly developing cluster of young leaves, called flush, by adult psyllids until the flush become infectious. We present experimental evidence showing that young flush become infectious within 15 d after receiving an inoculum of Candidatus Liberibacter asiaticus (bacteria). Using this critical fact, we specify a microsimulation model of asymptomatic disease spread and intensity in a grove of citrus trees. We apply a range of psyllid introduction scenarios to show that entire groves can become infected with up to 12,000 psyllids per tree in less than 1 y, before most of the trees show any symptoms. We also show that intervention strategies that reduce the psyllid population by 75% during the flushing periods can delay infection of a full grove, and thereby reduce the amount of insecticide used throughout a year. This result implies that psyllid surveillance and control, using a variety of recently available technologies, should be used from the initial detection of invasion and throughout the asymptomatic period.

Cartilage Status at Time of Arthroscopy Predicts Failure in Patients With Hip Dysplasia.

The purpose of our study was to determine whether chondral damage at the time of arthroscopy predicted conversion to THA in patients with dysplasia. We identified 166 patients with dysplasia who underwent hip arthroscopy. Forty-seven went on to receive THA. The articular cartilage of three regions of the acetabulum and femoral head were assessed for signs of chondral damage (absent, mild, or severe]). A stepwise multivariable logistic regression analysis revealed mild damage on the posterior femoral head (P=0.001) and severe damage on the anterior acetabulum (P=0.007) made a significant contribution to the predictor. The presence of mild posterior femoral head chondral changes was indicative of more global cartilage damage in this series of patients. Our findings show that chondral damage on the posterior femoral head and anterior acetabulum is a strong predictor of ultimate conversion to THA in dysplastic patients.

A flexible simulation platform to quantify and manage emergency department crowding.

BACKGROUND: Hospital-based Emergency Departments are struggling to provide timely care to a steadily increasing number of unscheduled ED visits. Dwindling compensation and rising ED closures dictate that meeting this challenge demands greater operational efficiency. METHODS: Using techniques from operations research theory, as well as a novel event-driven algorithm for processing priority queues, we developed a flexible simulation platform for hospital-based EDs. We tuned the parameters of the system to mimic U.S. nationally average and average academic hospital-based ED performance metrics and are able to assess a variety of patient flow outcomes including patient door-to-event times, propensity to leave without being seen, ED occupancy level, and dynamic staffing and resource use. RESULTS: The causes of ED crowding are variable and require site-specific solutions. For example, in a nationally average ED environment, provider availability is a surprising, but persistent bottleneck in patient flow. As a result, resources expended in reducing boarding times may not have the expected impact on patient throughput. On the other hand, reallocating resources into alternate care pathways can dramatically expedite care for lower acuity patients without delaying care for higher acuity patients. In an average academic ED environment, bed availability is the primary bottleneck in patient flow. Consequently, adjustments to provider scheduling have a limited effect on the timeliness of care delivery, while shorter boarding times significantly reduce crowding. An online version of the simulation platform is available at http://spark.rstudio.com/klopiano/EDsimulation/. CONCLUSION: In building this robust simulation framework, we have created a novel decision-support tool that ED and hospital managers can use to quantify the impact of proposed changes to patient flow prior to implementation.

Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis.

PURPOSE: This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects. METHODS: With a definition of safe zone of abduction (30-50°) and anteversion (5-25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects. RESULTS: There were 24 cups (71%) for abduction and 26 cups (76%) for anteversion located in the safe zone. Nineteen cups (56%) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening. CONCLUSIONS: The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.

Muscavirus (MdSGHV) disease dynamics in house fly populations--how is this virus transmitted and has it potential as a biological control agent?

The newly classified family Hytrosaviridae comprises several double-stranded DNA viruses that have been isolated from various dipteran species. These viruses cause characteristic salivary gland hypertrophy and suppress gonad development in their hosts. One member, Muscavirus or MdSGHV, exclusively infects adult house flies (Musca domestica) and, owing to its massive reproduction in and release from the salivary glands, is believed to be transmitted orally among feeding flies. However, results from recent experiments suggest that additional transmission routes likely are involved in the maintenance of MdSGHV in field populations of its host. Firstly, several hours before newly emerged feral flies begin feeding activities, the fully formed peritrophic matrix (PM) constitutes an effective barrier against oral infection. Secondly, flies are highly susceptible to topical virus treatments and intrahemocoelic injections. Thirdly, disease transmission is higher when flies are maintained in groups with infected conspecifics than when flies have access to virus-contaminated food. We hypothesize that interactions between flies may lead to cuticular damage, thereby providing an avenue to viral particles for direct access to the hemocoel. Based on our current knowledge, two options seem plausible for developing Muscavirus as a sterilizing agent to control house fly populations: The virus may either be formulated with PM-disrupting materials to facilitate oral infection from a feeding bait system, or amended with abrasive materials to enhance infection through a damaged cuticle after topical aerosol applications.

A Mathematic Model That Describes Modes of MdSGHV Transmission within House Fly Populations.

In this paper it is proposed that one potential component by which the Musca domestica salivary gland hypertrophy virus (MdSGHV) infects individual flies is through cuticular damage. Breaks in the cuticle allow entry of the virus into the hemocoel causing the infection. Male flies typically have a higher rate of infection and a higher rate of cuticular damage than females. A model for the transmission of MdSGHV was formulated assuming several potential and recognized means of transmission. The model yields results that are in agreement with field data that measured the infection rate in house flies on dairy farms in Florida. The results from this model indicate that MdSGHV will be maintained at a stable rate within house fly populations and support the future use of MdSGHV as a birth control agent in house fly management.

History of hip arthroscopy: challenges and opportunities.

Hip arthroscopy began with resection of pathologies and later progressed to repair of different tissues. There is an increasing impetus for reconstruction of biologic joints; although this has occurred with other joints, hip arthroscopic procedures are now headed in this direction. Thus, despite considerable initial challenges, multiple opportunities are now available in this fertile field.

What factors influence long-term survivorship after hip arthroscopy?

BACKGROUND: Hip arthroscopy is an evolving procedure. One small study suggested that a low modified Harris hip score and arthritis at the time of surgery were predictors of poor prognosis. QUESTIONS/PURPOSES: We therefore intended to confirm those findings with a large patient cohort to (1) determine the long-term nonarthritic hip score; (2) determine survivorship; (3) identify risk factors that increase the likelihood of THA; and (4) use those factors to create a usable risk assessment algorithm. PATIENTS AND METHODS: We retrospectively reviewed 324 patients (340 hips) who underwent arthroscopy for pain and/or catching. Of these, 106 patients (111 hips or 33%) had a minimum followup of 10 years (mean, 13 years; range, 10-20 years). The average age was 39 years (± 13) with 47 men and 59 women. We recorded patient age, gender, acetabular and femoral Outerbridge grade at surgery, and the presence of a labral tear. Followup consisted of a nonarthritic hip score or the date of a subsequent THA. We determined survivorship with the end point of THA for the acetabular and femoral Outerbridge grades. RESULTS: Overall survivorship among the 111 hips was 63% at 10 years. The average nonarthritic hip score for non-THA patients was 87.3 (± 12.1). Survivorship was greater for acetabular and femoral Outerbridge grades normal through II. Age at arthroscopy and Outerbridge grades independently predicted eventual THA. Gender and the presence of a labral tear did not influence long-term survivorship. CONCLUSIONS: The long-term survivorship of labral tears with low-grade cartilage damage indicates hip arthroscopy is reasonable for treating labral tears. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The role of arthroscopy in evaluation of painful hip arthroplasty.

UNLABELLED: Unexplained pain after hip arthroplasty is frustrating for patients and surgeons. We describe the use of hip arthroscopy in management of the painful hip arthroplasty, critically evaluate the outcomes of these patients, and refine indications for hip arthroscopy in this setting. We retrospectively reviewed 14 patients (16 hips) who underwent hip arthroscopy after joint replacement. One patient had suspected septic arthritis despite negative aspiration and one had known septic arthritis but was not a candidate for open arthrotomy; two had intraarticular migration of hardware. The remaining 10 patients (11 hips) had persistent pain despite negative diagnostic studies. The two patients (two hips) with infection were successfully treated with arthroscopic lavage and débridement plus intravenous antibiotics. Intraarticular metal fragments and a loose acetabular screw were successfully removed in two patients (three hips). Findings in the remaining 11 hips included a loose acetabular component (one); corrosion at the head-neck junction of a metal-on-metal articulation (one); soft tissue-scar impingement at the head/cup interface (four); synovitis with associated scar tissue (four); and capsular scarring with adhesions (one). Arthroscopy represented a successful treatment or directly led to a successful treatment in 12 of 16 hips. We observed no complications as a result of the arthroscopy. Arthroscopy may be of value in selected patients undergoing hip arthroplasty with unexplained pain after an inconclusive standard workup. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

A proximally coated beaded stem minimum 5-year follow-up.

This study reports the minimum 5-year clinical and radiographic outcome of a proximally beaded stem. A consecutive series of 159 primary uncemented total hip arthroplasties in 153 patients were evaluated clinically and radiographically by prospectively determined criteria. Radiographic results showed 97% of the femoral stems are bone ingrown and stable by Engh criteria. There have been 5 femoral revisions (2 for subsidence, 2 for loosening, and 1 broken trunion). At minimum 5-year follow-up, this femoral stem has demonstrated reliable clinical function, bone ingrowth, and proximal bone preservation.

Complex revision total hip arthroplasty with modular stems at a mean of 14 years.

We retrospectively reviewed 87 patients (92 hips) who had revision hip surgery to determine whether a proximally coated, modular femoral component would remain stably fixed at long-term followup. Thirteen patients died and 12 patients were lost to followup leaving 62 patients (67 hips) available for review with minimum followup of 8 years (mean, 14 years; range, 8-17 years). Preoperative radiographs were reviewed using Paprosky's classification. Postoperative radiographs were reviewed for osteolysis, endosteal hypertrophy, cortical hypertrophy, distal pedestals, component breakage, and loosening. Thirty-seven hips underwent femoral allografting, 10 of which were proximal femurs. With revision as the endpoint the Kaplan-Meier survivorship (including deaths and loss to followup) was 60% at 14 years. Forty-seven of the 57 (82%) noncemented stems were bone ingrown. All had relative proximal bone preservation and 33 of 57 (58%) had bone hypertrophy in the diaphysis around zones 2 and 6. There were five aseptic failures (9%). Each of those was Paprosky Class IIIB or IV preoperatively. There were no long-term failures in Paprosky Class II or IIIA. The aseptic failures have been re-revised. This modular stem resulted in reliable fixation with relative preservation of proximal bone stock at this intermediate interval in complex revisions in Paprosky Class II and IIIA. Paprosky Class IIIB and IV defects may need additional component fixation options.

Hip arthroscopy: indications, outcomes, and complications.

Hip arthroscopy is technically demanding, with a steep learning curve, and requires special distraction tools and operating equipment. Access to the hip joint is difficult because of the resistance to distraction resulting from the large muscular envelope, the strength of the iliofemoral ligament, and the negative intra-articular pressure. This operation should not be done without specific education in its methods.

Constrained acetabular components in complex revision total hip arthroplasty.

UNLABELLED: We retrospectively reviewed 39 consecutive hips in 38 patients to examine the outcome of acetabular fixation and stability in patients with the tripolar constrained acetabular component who had complex revision surgery at 2 to 5 years of followup. Preoperative indications included recurrent dislocation, loose acetabular component with instability, migrated bipolar, resection arthroplasty conversions, and primary arthroplasty. Postoperative radiographs were reviewed for radiolucencies, loosening, migration, or breakage. The patients' average age was 65 years (range, 44-83 years). Thirty-five of the 39 acetabular components (91%) are well fixed and bony ingrown. There were no dislocations. One patient was involved in an motor vehicle accident 1 year postoperatively and sustained a fracture of the ilium and a 2 mm radiolucency about the component which is now stable. Three patients had acetabular revisions. Two patients were revised to a tripolar cemented into a cage and are doing well. The tripolar constrained acetabular component offers reliable fixation and joint stability in patients at high risk for dislocation in this short term followup. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for s complete description of levels of evidence.

Factor structure of organizational commitment: differences between U.S. and South Korean samples.

The current study compared the factor structures of the construct of organizational commitment between two samples of financial employees, one from the U.S. (n = 103) and one from South Korea (n = 109). Participants completed a 26-item questionnaire. Two factors (an affective component and a normative component) emerged for the U.S. sample; only one factor for the Koreans. Results suggest that culture should be considered when trying to assess organizational commitment.

Arthroscopic intervention in early hip disease.

Advancement in diagnostic and therapeutic applications for hip arthroscopy have dispelled previous myths about early hip disease. Arthroscopic findings have established the following facts: Acetabular labral tears do occur; acetabular chondral lesions do exist; tears are most frequently anterior and often associated with sudden twisting or pivoting motions; and labral tears often occur in association with articular cartilage lesions of the adjacent acetabulum or femoral head, and if present for years, contribute to the progression of delamination process of the chondral cartilage. Magnetic resonance arthrography represents an improvement over conventional magnetic resonance imaging, it does have limitations when compared with direct observation. Although indications for hip arthroscopy are constantly expanding, the most common indications include: labral tears, loose bodies, chondral flap lesions of the acetabular or femoral head, synovial chondromatosis, foreign body removal, and crystalline hip arthropathy (gout, pseudogout, and others). Contraindications include conditions that limit the potential for hip distraction such as joint ankylosis, dense heterotopic bone formation, considerable protrusio, or morbid obesity. Complication rates have been reported between 0.5 and 5%, most often related to distraction and include sciatic or femoral nerve palsy, avascular necrosis, and compartment syndrome. Transient peroneal or pudendal nerve effects and chondral scuffing have been associated with difficult or prolonged distraction. Meticulous consideration to patient positioning, distraction time and portal placement are essential. Judicious patient selection and diagnostic expertise are critical to successful outcomes. Candidates for hip arthroscopy should include only those patients with mechanical symptoms (catching, locking, or buckling) that have failed to respond to conservative therapy. The extent of articular cartilage involvement has the most direct relationship to surgical outcomes. Improvements in technique and instrumentation have made hip arthroscopy an efficacious way to diagnose and treat a variety of intra-articular problems.

Factor structure of the strong interest inventory with a Chinese high school sample.

D. S. Goh and J. Yu (2001) translated the Strong Interest Inventory (SII; L. W. Harmon, J-I. Hansen, F. H. Borgen, & A. L. Hammer, 1994) into Chinese and identified a 6-factor structure of the new instrument that showed both similarities and differences with J. L. Holland's personality types (1966, 1985, 1997). The present study was undertaken to further investigate the construct validity of the SII-Chinese for a sample of 247 high school students in China. Confirmatory factor analyses did not find a good fit of the Goh and Yu (2001) model or the Holland hexagonal model to the present data. Exploratory factor analysis extracted a 3-factor solution accounting for 59.2% of the variance. The authors offer interpretations of the obtained factors and discuss implications for the use of the SII-Chinese as an assessment tool.

Reasons for use of the family and medical leave act by sex and age.

Applications (completed between 1995 and 2000) for leave by full-time staff employees working for a southeastern university of moderate size were examined by sex and age. Chi-square tests for frequencies of requests by reason (care for others vs own health condition) for taking leave were not associated with sex but were associated with age. The Family and Medical Leave Act may help both men and women assume dual roles of worker and family caregiver. Older workers were more likely to take leave to care for their own health condition than to care for others.

Anatomy, pathologic features, and treatment of acetabular labral tears.

There is an evolving body of knowledge regarding the acetabular labrum. Labral tears are most frequently anterior and often are associated with sudden twisting or pivoting motions. High clinical suspicion in association with positive physical findings are fundamental for the clinician to properly determine treatment for the suspected tear. Labral tears, especially those present for years, may contribute to the progression of hip osteoarthritis. Patients at risk include those with developmental dysplasia, those with tears greater than 5 years, and those with associated chondral full-thickness lesions. Chondral injuries may occur in association with a multitude of hip conditions including labral tears, loose bodies, osteonecrosis, slipped capital femoral epiphysis, dysplasia, and degenerative arthritis. Labral tears occurring at the watershed zone may destabilize the adjacent acetabular conditions. Arthroscopic observations support the concept that labral disruption, acetabular chondral lesions, or both frequently are part of a continuum of degenerative joint disease.