Effect of surgical parameters on the biomechanical behaviour of bicondylar total knee endoprostheses - A robot-assisted test method based on a musculoskeletal model.

The complicated interplay of total knee replacement (TKR) positioning and patient-specific soft tissue conditions still causes a considerable number of unsatisfactory outcomes. Therefore, we deployed a robot-assisted test method, in which a six-axis robot moved and loaded a bicondylar cruciate-retaining (CR)-TKR in a virtual lower extremity emulated by a musculoskeletal multibody model. This enabled us to systematically analyse the impact of the posterior cruciate ligament (PCL), tibial slope, and tibial component rotation on TKR function while considering the physical implant components and physiological-like conditions during dynamic motions. The PCL resection yielded a decrease of femoral rollback by 4.5 mm and a reduction of tibiofemoral contact force by 50 N. A reduced tibial slope led to an increase of tibiofemoral contact force by about 170 N and a decrease of femoral rollback up to 1.7 mm. Although a higher tibial slope reduced the contact force, excessive tibial slopes should be avoided to prevent joint instability. Contrary to an external rotation of the tibial component, an internal rotation clearly increased the contact force and lateral femoral rollback. Our data contribute to improved understanding the biomechanics of TKRs and show the capabilities of the robot-assisted test method based on a musculoskeletal multibody model as a preoperative planning tool.

Surgery for lumbar disc herniation: Analysis of 500 consecutive patients treated in an interdisciplinary spine centre.

Surgical removal of a symptomatic herniated lumbar disc is performed either with or without the support of a microscope. Up to the time of writing, the literature has reported similar clinical outcomes for the two procedures. Five hundred consecutive patients, operated upon for primary single-level lumbar disc herniation in our University Spine Center between 2003-2011, with (n=275), or without (n=225), the aid of a microscope were included. Data were retrospectively analyzed, comparing the primary endpoint of clinical outcome and the secondary endpoints of complications, surgical time and length of hospitalization. Clinical outcomes and reoperation rates were comparable in both groups. Surgical time was significantly shorter with a mean time of 47minutes without use of the microscope compared to the mean time of 87minutes (p<0.001) with the use of the microscope. Mean length of hospitalization was shorter in those operated with the microscope (5.3days) compared to those without (6.1days, p=0.004). There was no difference in rates of complications. Microdiscectomy versus open sequestrectomy and discectomy for surgical treatment of lumbar disc herniation is associated with similar clinical outcomes and reoperation rates. Open sequestrectomy is associated with shorter operation times. Microdiscectomy is associated with shorter hospitalization stays.

Are preoperative sex-related differences of affective symptoms in primary brain tumor patients associated with postoperative histopathological grading?

Our objective was to explore the impact of the histopathological tumor type on affective symptoms before surgery among male and female patients with supratentorial primary brain tumors. A total of 44 adult patients were included in the study. Depression and anxiety were measured using the Beck Depression Inventory (BDI) and the State-Trait Anxiety Inventory. Additionally, clinical interviews, including the Hamilton Depression Rating Scale (HDRS), were conducted. The general function of patients was measured with the Karnofsky Performance Status scale (KPS). All measures were obtained before surgery and therefore before the final histopathological diagnosis. All self-rating questionnaires but not the HDRS, showed significantly higher scores in female patients. The functional status assessed with the KPS was lower in female patients and correlated to the somatic part of the BDI. We further found a tendency for higher HDRS scores in male patients with a WHO grade 4 tumor stage compared to female patients. This finding was supported by positive correlations between HDRS scores and WHO grade in male and negative correlations between HDRS scores and WHO grade in female patients. In conclusion the preoperative evaluation of affective symptoms with self-rating questionnaires in patients with brain tumors may be invalidated by the patient's functional status. Depression should be explored with clinical interviews in these patients. Sex differences of affective symptoms in this patient group may also be related to the malignancy of the tumor, but further studies are needed to disentangle this relationship.

Antibiotic-impregnated versus silver-bearing external ventricular drainage catheters: preliminary results in a randomized controlled trial.

BACKGROUND: Evaluation of antibiotic-impregnated (AI) and ionized silver particle coated external ventricular drainage catheters (EVD) in patients with subarachnoid (SAH) or intracranial hemorrhage (ICH). METHODS: Between February 2011 and June 2012, 40 patients with acute hydrocephalus due to SAH, ICH or intraventricular hemorrhage were enrolled in a prospective, randomized, mono-center pilot study. Primary endpoints were defined as: number of events of cerebrospinal fluid (CSF) infections. Secondary endpoints were defined as: neurosurgical complications following the placement of the EVD, number of revisions of EVD catheters, and cost effectiveness. RESULTS: Sixty-one EVD placements in 40 patients, 32 antibiotic-coated (Bactiseal(®)), 29 silver-bearing catheters (VentriGuard(®)), have been performed. Confirmed or high suspicion of CSF infections occurred in 11 out of 61 events (confirmed infection: p = 0.71, probable infection: p = 0.90). Revisions of EVD were needed in 13 cases (22 %) due to CSF infection, dysfunction, impaired healing, or malplacement (p = 0.37). CONCLUSION: Regarding CSF infection rate and dysfunction, no statistical significant differences between the two EVD catheters Bactiseal(®) versus VentriGuard(®) were found. The silver-bearing catheter might offer a safe and cost-conscious alternative to the AI catheter.

[Musculoskeletal modeling of the patellofemoral joint. Dynamic analysis of patellar tracking]. / Muskuloskelettale Modellierung des patellofemoralen Gelenks. Dynamische Analyse der patellaren Führung.

Numerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.

Acquired immunodeficiency syndrome in Alabama: special concerns for black women.

BACKGROUND: Among AIDS case reports from rural and small town areas of the United States, rates are higher in the South than in any other part of the country. METHODS: For this study, we analyzed AIDS surveillance statistics from the state of Alabama for trends, distributions, and populations affected. We aggregated Alabama AIDS surveillance data in 5-year intervals--1981 to 1985, 1986 to 1990, 1991 to 1995--and made comparisons based on geographic area of residence of people diagnosed with AIDS. RESULTS: Of the 3,558 cases of AIDS reported in Alabama in the period 1981 to 1995, 86% were men and 14% were women. Among women, 69.7% were black and 29.1% were white. Among men, 48.4% were black and 50.9% were white. We compared these figures with 1995 Alabama population estimates of 26.2% black, 73.7% white, and < 1% another race. The rates for black women and white women increased 170-fold and 23-fold, respectively, from the 1981 to 1985 period to the 1991 to 1995 period. For the same periods, case rates for black men and white men increased more than 80-fold and 50-fold, respectively. Black women showed a rise per 100,000 population-from 0.3 (1981 to 1985) in both northern and southern Alabama to 37 in northern Alabama and 64 in southern Alabama (1991 to 1995). CONCLUSIONS: Black women are at disproportionately high risk, particularly in the southern counties of Alabama. HIV is increasingly prevalent in rural and small town communities in Alabama and is more often transmitted heterosexually than it has been previously.

Control of epidemic early syphilis: the results of an intervention campaign using social networks.

BACKGROUND: During an epidemic of early syphilis, social networks were used for an intervention campaign. GOAL OF THIS STUDY: To characterize the epidemic and describe the yield of new cases from index-case interviews. METHODS: Analyses of morbidity data collected by the Montgomery County, Alabama, sexually transmitted disease program determined the course of the epidemic and characterized the new case yields from social networks identified via index-case interviews (partner notification investigations) and interviews with sex partners and their associates (cluster investigations). Results and costs were compared to a noncampaign period. RESULTS: The number of reported syphilis cases nearly doubled from 1990 to 1991 (201 to 348 per 100,000 residents). During the 21-week campaign, 373 case-patients had partner notification/cluster investigations; 113 (11%) of 984 sex partners and 41 (3%) of 1,146 high-risk associates (persons identified during cluster investigations) had syphilis. No subgroup of case-patients for which the partner notification/cluster investigation yielded more infected persons than other subgroups was identified. The cost per case detected was more than twice that during a noncampaign period ($1,627 vs. $771). CONCLUSION: Partner notification investigations yielded more infected persons than cluster investigations. Further evaluation is needed to determine the role of intense partner notification/cluster investigators' efforts in the control of epidemic syphilis.

Immune response to intramuscular revaccination after primary intradermal vaccination against hepatitis B.

We studied the immune response to (re)vaccination with three 1-mL doses of recombinant hepatitis B vaccine administered intramuscularly on days 0, 30, and 180 to 75 public safety workers (PSWs) who had not developed antibody to hepatitis B surface antigen (anti-HBs) after three intradermal doses of hepatitis B vaccine; to 45 PSWs who had initially developed antibody but did not have detectable levels 11 months after intradermal vaccination; and to 16 hepatitis B-susceptible PSWs. Levels of anti-HBs were measured on days 14 and 210 after the first intramuscular dose. Overall, 46 (61%) of 75 PSWs in the initial-nonresponse group, 43 (96%) of 45 PSWs in the lost-response group, and 5 (31%) of 16 PSWs in the new-vaccinee group had anti-HBs titers of > or = 10 mIU/mL on day 14. On day 210 (after three doses), the figures were 62 (89%) of 70 PSWs in the initial-nonresponse group, 43 (98%) of 44 PSWs in the lost-response group, and 15 (94%) of 16 PSWs in the new-vaccine group. We conclude that persons who do not seroconvert after intradermal vaccination should receive three doses of hepatitis B vaccine by the intramuscular route.

PMR study of mortality among Alabama workers and farmers.

Computerized records of all Alabama deaths occurring to persons 16 years of age and over for the 5-year period 1984-1988 were obtained from the Alabama Department of Public Health. Using proportionate mortality ratio (PMR) methodology and death certificate occupation, cause-specific mortality patterns were examined for all Alabama decedents (N = 182,178), for all Alabama workers (N = 125,369), and for the occupational group of "farm operators and managers" (N = 11,691). In comparison with the U.S. general population, little difference was found between cause-specific PMR results for the total Alabama population and those for all workers, suggesting the absence of a generalized "healthy worker effect." In comparison with the U.S. population, PMR results for farmers suggested lowered mortality from all malignant neoplasms and all heart disease, and elevated mortality from all external causes of death. In comparison with the Alabama population, PMR results for farmers continued to suggest lowered mortality from all malignant neoplasms, specifically for cancers of the respiratory, digestive and lymphopoietic systems. However, significantly elevated PMRs for external causes of death appeared only among nonwhite female farmers. Further investigation of these deaths suggested that this finding was more likely attributable to an increased risk of housefire deaths associated with rural lifestyle than with occupational factors.

Invasive group A streptococcus carriage in a child care centre after a fatal case.

After a fatal case of invasive group A streptococcal disease, serotype T-1, in a child care centre, group A streptococcal T-1 prevalence was measured and risk factors for carriage were determined. A total of 87% (224/258) had throat culture tests. Group A streptococcus was isolated from 57 (25%), and of the 50 isolates serotyped, 38 (76%) were T-1. Group A streptococcal T-1 prevalence was 18% (38/217) and six of nine rooms had children with group A streptococcal T-1 isolates. The risk of group A streptococcal T-1 carriage was increased for children who shared the index case's room (odds ratio (OR) = 2.7; 95% confidence interval (CI) = 0.8 to 9.4) and for each additional hour per week in child care (OR = 1.03; 95% CI = 1.001 to 1.061); and decreased in children taking antibiotics in the preceding four weeks (OR = 0.2; 95% CI = 0.1 to 0.9). Carriage of the invasive group A streptococcal strain could not be determined by identified risk factors alone.

Prevalence of illicit drugs detected in the urine of women of childbearing age in Alabama public health clinics.

Each year, it is estimated that from 350,000 to 739,000 U.S. infants are exposed in utero to one or more illicit drugs. To estimate the prevalence of and risk factors for illicit drug use by women of childbearing age in Alabama, during 2 months in 1991 the authors collected patient-reported histories, clinical histories, and urine specimens from 6,195 women statewide attending public health maternity clinics, family planning clinics, and a high-risk referral obstetrical clinic. Blind drug screening of urine specimens for marijuana, cocaine, opiates, barbiturates, and amphetamines was performed with the use of a fluorescent polarization immunoassay. The overall prevalence of positive results for drugs tested was 10.1 percent, including 8.4 percent of the 3,554 pregnant and 12.3 percent of the 2,571 nonpregnant women screened. The drugs most frequently detected were marijuana and cocaine. Characteristics of the subjects associated with a higher prevalence of positive results for any drug tested or for marijuana included white race, older age, being divorced, non student occupation, having 12 or less years of education, attending a clinic located in a suburban county, self-reported substance use, increased risk for human immunodeficiency virus infection, and reproductive history. Characteristics of women with positive screening for cocaine results were similar to those who tested positive for any drug, except that the prevalence of cocaine was higher among black women and those attending urban county clinics and did not vary by years of education. Patient-reported histories of drug use were insensitive in identifying women who had positive drug screening results (sensitivity, 6.3 percent; specificity, 98.2 percent). Thus, in this study,the use of illicit drugs among women of childbearing age attending public clinics in Alabama was common and emphasizes the need for targeted drug education and interventions to reduce the impact of drug use on this high-risk population.

Elevated blood lead levels associated with illegally distilled alcohol.

Whiskey produced in illegal stills (ie, "moonshine") remains an important and underappreciated source of lead toxicity in some rural counties of the Southeast. From March 5 through October 26, 1991, eight adult patients with elevated blood lead levels were identified at a rural county hospital in Alabama and were reported to the Alabama Department of Public Health notifiable disease surveillance system. A case-patient was defined as any person 17 years of age or more who presented to the hospital from January 1, 1990, through December 31, 1991, and had a blood lead level of 0.72 mumol/L or more (15 micrograms/dL or more). To identify cases and potential sources of lead exposure, we reviewed medical and laboratory records from the hospital, interviewed patients with elevated blood lead levels, and determined the lead content of moonshine samples. Nine patients met the case definition, including one patient who was not reported to the state. Patients ranged in age from 28 to 62 years; blood lead values ranged from 0.77 to 12.50 mumol/L (16 to 259 micrograms/dL). The most frequent signs of possible lead toxicity included seizures (six), microcytic anemia (five), and encephalopathy (two); one patient died. The only identified source of lead exposure for the nine patients was moonshine ingestion. Moonshine samples available from local stills contained sufficient amounts of lead (340 to 4600 mumol/L) to result in the observed blood lead levels. This investigation emphasizes the adverse health effects and ongoing public health impact of moonshine ingestion.

Outbreak of Pseudomonas cepacia bacteremia in oncology patients.

In 1991, an outbreak of Pseudomonas cepacia bacteremia (PCB) occurred among patients at an oncology clinic in Alabama. A case-patient was defined as any patient at Alabama Oncology Hematology Associates (AOHA) who had at least one blood culture positive for P. cepacia from 7 August through 31 October. Fourteen case-patients were identified; all required hospitalization (median duration, 17 days), but none died of PCB. A cohort study assessing risk factors for PCB focused on all patients who had been treated on the 8 days when case-patients had last visited AOHA during the period 7-21 August. Only patients with central venous catheters developed PCB (P < .001). Among patients with central venous catheters, PCB occurred only after visits to AOHA at which the catheters were flushed with heparin solution in the AOHA laboratory rather than in the treatment area (P < .001). P. cepacia was cultured from the only intravenous fluid bag used to prepare heparin flush solution in the laboratory during the interval 7-21 August. All outbreak-associated isolates of P. cepacia had an identical DNA ribotype pattern. These findings emphasize the importance of avoiding multiple use of single-use solutions, especially for high-risk patients with long-term indwelling central venous catheters.

An outbreak of acute nonbacterial gastroenteritis in a nursing home.

OBJECTIVE: To determine risk factors for and modes of transmission of an outbreak of acute nonbacterial gastroenteritis among residents and staff in a nursing home. DESIGN: Cohort study of residents and questionnaire survey of employees. SETTING: One hundred twenty-bed nursing home in Alabama. PATIENTS: From July 11, 1991, through July 25, 1991, 77 of 120 residents (attack rate = 64%) and at least 14 of 49 employees (minimum attack rate = 29%) developed acute gastroenteritis characterized by vomiting and diarrhea; few residents developed fever > 100 degrees F. Nine residents required intravenous rehydration, and 2 residents died. RESULTS: The risk of developing illness was greater for female residents (64/92 versus 13/28; relative risk [RR] = 1.5; 95% confidence interval [CI95] = 1.0-2.3) and for employees who reported handling residents' soiled linen, stools, or vomitus more frequently (> 5 times a shift versus < or = 5 times a shift: 7/13 versus 7/31; RR = 2.4; CI95 = 1.1-5.4). Direct transmission of infection, probably via person-to-person spread, sustained the outbreak. Temporal clustering analysis demonstrated that the risk of becoming ill 1 or 2 days after a roommate became ill was significantly greater than that of becoming ill at other times during the outbreak (RR = 2.2; CI95 = 1.3-3.8). No Salmonella or Shigella species, ova, or parasites were identified from 12 fecal specimens obtained from ill residents. CONCLUSIONS: Although stool and serum specimens were not available for viral studies, the clinical symptoms and incubation period were consistent with illness due to Norwalk-like viral agents. This outbreak emphasizes the severity of acute nonbacterial gastroenteritis among elderly and debilitated residents of nursing homes and the need for prompt use of enteric precautions in controlling outbreaks of gastroenteritis in these facilities.

Staff patterns of epidemiologists in the health departments of 12 southern states.

In November 1989, representatives from 12 States attending the Annual Convocation of Southern State Epidemiologists completed a survey to enumerate epidemiologists working in central offices of State health departments. Epidemiologists were classified according to education and program area. A total of 117 epidemiologists were identified, yielding a range among the States of 0.6 to 8.3 (median 1.9) epidemiologists per million population. The most common degree was a medical degree, followed by master's training in epidemiology or biostatistics; only 9 percent had doctoral training in epidemiology or biostatistics. More than one-third of the epidemiologists worked in infectious diseases, including acquired immunodeficiency syndrome (AIDS) and sexually transmitted diseases, and about one-fifth worked in environmental epidemiology. The areas of injuries, cancer, chronic diseases, maternal and child health, and occupational health collectively accounted for about one-fifth of epidemiologists. The results of the survey suggest room for further epidemiologic training among health department epidemiologists. The results also identify areas where additional epidemiologic input would be beneficial.

Surveillance for Lyme disease in Alabama.

To estimate the frequency of occurrence of Lyme disease in Alabama, in September 1988 the Department of Public Health requested physicians and laboratories to begin voluntary reporting of cases of Lyme disease. Thirteen cases, 5 confirmed, 1 probable, 4 presumptive and 3 possible, were reported for the years 1986-1988. Counties in which tick exposure likely occurred included Calhoun, Cleburne, Mobile, Monroe, Shelby, Talladega and Tallapoosa. Lyme disease occurs in Alabama but appears to be uncommon.

Human parvovirus B19 infection during pregnancy.

Human parvovirus B19 (B19) has been implicated as the cause of fifth disease and has been associated with fetal death. We identified pregnant women who were at risk of contracting B19 infection during an outbreak of fifth disease. The sera of 12 women classified at high risk of exposure and 19 classified at low risk were tested during prenatal care, at delivery, or at both times for IgG and IgM antibodies to B19. Four women at high risk but none at low risk were considered infected because they were IgM positive. One IgM-positive woman gave birth to a stillborn hydropic fetus whose tissues were positive for B19 DNA by a nucleic acid hybridization assay. The other three IgM-positive women gave birth to normal offspring, of whom one had IgM-positive cord serum. We conclude that B19 infection during pregnancy can lead to fetal infection with at least two associated outcomes--no adverse effect on the fetus or fetal death.