Biomedical subjects

K L Armstrong

Publications and source records attributed to K L Armstrong.

At least 19 recordsLinked to original sources

PubMed2006

Living with congenital adrenal hyperplasia in Vietnam: a survey of parents.

OBJECTIVE: Congenital adrenal hyperplasia (CAH) has the potential to place an enormous burden on families in resource-poor countries, and the aim of this survey was to provide more specific insights into the difficulties faced by families living with CAH in Vietnam. It is hoped that this information will be used to ensure that future efforts to reduce the burden of CAH are as effective, sustainable and appropriate as possible. DESIGN AND METHODS: A questionnaire-based needs assessment survey was offered to parents of children with CAH who were attending the Annual CAH Support Group Meeting held at the National Hospital of Pediatrics (NHP) in Hanoi, Vietnam, on 10th June 2005. RESULTS: Fifty-three families responded to the questionnaire. Information pertaining to the purchase and use of medication to treat CAH, access to medical care, surgical treatment for girls, and a wide range of parental concerns was collected. CONCLUSIONS: This survey highlights the heavy burden that CAH places on families in Vietnam, and provides significant insights into various initiatives that could well help ease this suffering. In particular, efforts must be made to ensure essential medication is affordably available, communication of important messages to parents is enhanced, local support groups encouraged, and early diagnosis and medical treatment of CAH optimized so as to reduce morbidity and mortality.

Adolescent↗

PubMed2002

Professional telephone advice to parents with sick children: time for quality control!

OBJECTIVE: To assess the quality of professional telephone advice given to parents with sick children. METHODS: All hospitals with an emergency department and a paediatric ward and a designated child health telephone advice line in the greater Brisbane region were invited to participate in the study. Case scenarios involving a febrile baby, a 14-month-old with gastroenteritis and an 18-month-old with a head injury were used three times with each institution. Each of the cases should have elicited a response indicating the need for urgent medical attention. A research assistant presented the symptoms in accordance with the questions of the telephone advice-giver. Aspects of the call were recorded, including time between call made and access to advice-giver, profession of advice-giver, identifying details sought by advice-giver, questions asked about the case presented, length of call, and advice-given. RESULTS: Of the 10 hospitals asked, six agreed to participate. Included in the study were two paediatric hospitals, two general public hospitals, one private hospital, and a Statewide-designated child health telephone advice line. Calls were generally attended to promptly. Only 37 (68.5%) of the advisers recognized the urgency of the case scenarios, with the febrile infant having the least likelihood of eliciting the correct advice (39%). Doctors gave more reliable advice than nurses in the fever scenario, but not in the other cases. CONCLUSIONS: Telephone advice to parents with sick children is easily accessible, but is often dangerously inappropriate. There is a need for tighter quality control and/or for a centralised telephone advice line to prevent inappropriate advice being given to parents.

Child↗

PubMed2001

Comparative fecundity and survival rates of phlebotomus papatasi sandflies membrane fed on blood from eight mammal species.

Female sandflies, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae), were fed via chicken membrane on heparinized blood from eight species of mammal (human, horse, cow, pig, dog, rabbit, guinea-pig, hamster) and their reproductive success rates were compared. No appreciable differences between those fed on human and animal blood were detected with respect to the proportion of flies that fed successfully, mortality-rate within 24h, number of eggs laid per blood-fed female or egg viability. When mass-rearing sandflies for research purposes, membrane-feeding avoids practical difficulties encountered if sandflies are allowed to feed on live hosts (i.e. anaesthesia, distress from handling and postfeeding inflammation) and reduction of sandfly fecundity due to host antibody interference. Use of animal blood also eliminates risks of accidental transmission of human blood-borne pathogens, e.g. hepatitis B and human immunodeficiency virus (HIV), and is less expensive than maintenance of animals and their preparation for sandfly feeding.

Animals↗

PubMed2001

Role of dispersion of atrial refractoriness in the recurrence of clinical atrial fibrillation; a manifestation of atrial electrical remodelling in humans?

AIMS: The mechanism of atrial fibrillation recurrence following cardioversion is unknown, although experimental studies have indicated that changes in dispersion of atrial refractoriness may play a role. The aims of this study were to assess (1) if dispersion of atrial refractoriness is relevant to atrial fibrillation recurrence and (2) if dispersion of refractoriness is part of the atrial electrical remodelling process in humans. METHODS AND RESULTS: Thirty-seven consecutive patients underwent internal cardioversion (CV1) of persistent atrial fibrillation. Patients were monitored by daily transtelephonic recordings following discharge and if there was spontaneous atrial fibrillation recurrence they were rapidly admitted for repeat cardioversion (CV2). We used the 5th percentile of 100 consecutive atrial fibrillation cycle lengths (AFCL(P5)) and the atrial effective refractory period (AERP) as measures of atrial refractoriness at four different atrial sites. Dispersion of AFCL(P5)at CV1 was significantly higher in those who had subsequent recurrence of atrial fibrillation than in those who remained in sinus rhythm for at least 1 month after cardioversion (35+/-17 ms vs 9+/-13 ms;P<0.02). Dispersion of AFCL(P5)measured at CV2 was significantly lower than that measured in the same patients at CV1 (19+/-8 ms vs 35+/-11 ms;P=0.02). i.e. dispersion of AFCL(P5)had reduced following a period of sinus rhythm. In contrast, there was no difference in dispersion of AERP between the recurrers and non-recurrers. Dispersion of AERP between CV1 and CV2 did not change following a period of sinus rhythm. CONCLUSION: Dispersion of AFCL is relevant to atrial fibrillation recurrence and may represent a manifestation of atrial electrical remodelling in humans. Treatment directed at AFCL dispersion may be useful in the suppression of atrial fibrillation recurrence following cardioversion.

Adult↗

PubMed2000

Antioxidant loading reduces oxidative stress induced by high-energy impulse noise (blast) exposure.

Detonation of explosives, firing of large caliber weapons and occupational explosions, professional or accidental, produce high-energy impulse noise (blast) waves characterized by a rapid rise in atmospheric pressure (overpressure) followed by gradual decay to ambient level. Exposure to blast waves causes injury, predominantly to the hollow organs such as ears and lungs. We have previously reported that blast exposure can induce free radical-mediated oxidative stress in the lung characterized by antioxidant depletion, lipid peroxidation, and hemoglobin (Hb) oxidation. In this study, we examined whether pre-loading, adequately fed rats, with pharmacological doses of antioxidants would reduce the response to blast. Sprague-Dawley rats weighing 300-350 g were loaded with either 800 IU vitamin E (VE), 1000 mg vitamin C (VC) or 25 mg lipoic acid (LA) for 3 consecutive days by gavage before exposure to blast. Both VE, and LA were dissolved in 2 ml corn oil, but VC in 2 ml water. After the 3-day antioxidant loading, the rats were divided into six groups (five rats per group), deeply anesthetized with sodium pentobarbital (60 mg/kg body weight), then exposed to a low-level blast (62+/-2 kPa peak pressure and 5 ms duration). A matched number of groups were sham exposed and served as controls. One hour after exposure, all rats were euthanized then blood, and lung tissue was analyzed. We found that antioxidant loading resulted in restored Hb oxygenation, and reduced lipid peroxidation. Lung tissue VE content was elevated after loading but VC did not change possibly due to their different bioavailability and saturation kinetics. These observations, suggest that brief antioxidant loading with pharmacological doses can reduce blast-induced oxidative stress, and may have occupational and clinical implications.

Animals↗

PubMed2000

Home visiting intervention for vulnerable families with newborns: follow-up results of a randomized controlled trial.

OBJECTIVE: This study aimed to: (1) Assess the community utility of a screening tool to identify families with child abuse or neglect risk factors in the immediate postnatal period (2) Determine the social validity and effectiveness of a home visiting program using community child health nurses and offering social work services for identified families, and (3) Identify factors in the immediate postnatal period associated with the child's environment that predict poor adjustment to the parenting role. METHOD: A randomized controlled trial using a cohort of 181 families was undertaken to evaluate the impact of a home visiting program. Mothers were recruited in the immediate postnatal period and allocated either into the home visiting program or into a comparison group. The research design required self-identification into the study by providing positive responses to a range of risk factors. A repeated measures design was used to test parenting stress and maternal depression from the immediate postnatal period to 12-month follow-up and physical child abuse potential to 18-month follow-up. To test whether measures taken in the immediate postnatal period were predictive for poor adjustment to the parenting role, a linear regression model was used. RESULTS: The screening procedure was shown to have utility in the context of recruitment to a research trial and mothers were willing to accept the home visiting program examined by this study from the immediate postnatal period. From as early as 6 weeks the program demonstrated ability to impact positively on maternal, infant, family, and home environment variables (testing 90 randomly allocated intervention vs. 91 comparison families). At follow-up, parental adjustment variables were not significantly different between groups (testing the remaining 68 (75.5%) intervention vs. 70 (76.9%) comparison families) and home environment assessment scores had converged. Predictive analysis of factors measured in the immediate postnatal period revealed an absence of any predictive value to demographic characteristics, which secondary prevention efforts typically target. CONCLUSIONS: Follow-up evaluation did not demonstrate a positive impact on parenting stress, parenting competence, or quality of the home environment confirming the need to test early program success on longer term outcomes. Further, thestudy not only demonstrated that there was a relationship between maternal, family and environmental factors identified in the immediate postnatal period. and adjustment to the parenting role, but also challenged demographic targeting for child abuse and neglect risk. At the same time, the immediate postnatal period presented an exciting window of opportunity to access high-risk families who may otherwise have become marginalized from traditional services.

Adaptation, Psychological↗

PubMed2000

Rib fractures in infants: red alert! The clinical features, investigations and child protection outcomes.

OBJECTIVE: To examine clinical features, investigation methods and outcomes of infants with rib fractures. METHODOLOGY: All infants aged 2 years or younger who presented over a 5-year period with documented rib fractures were identified from the medical records database of a tertiary referral paediatric hospital and data collected by retrospective chart review. Additional data regarding notifications and placements were obtained from the Department of Families Youth and Community Care, Queensland. RESULTS: Rib fractures were attributed to child abuse in 15 of 18 infants identified. The initial presentation in the abused infants was most often as a result of intracranial pathology and limb fractures. In four cases the rib fractures were incidental findings when abuse had not been suspected. Bone scintigraphy revealed eight previously undetected rib injuries in four cases. In three cases of abuse, the rib fractures were an isolated finding. Three of the infants with inflicted rib injuries were discharged home. In one such infant a significant re-injury occurred. Three returned home with implicated adults no longer in residence, and nine spent a mean period of 12 months in foster care. CONCLUSIONS: Rib fractures in infancy are usually caused by severe physical abuse. Accidental rib fractures are rare in infants and result from massive trauma. Rib fractures, multiple or single, may occur in isolation in abused infants. The implications of such injuries must be recognized to ensure appropriate, safe and consistent child protection outcomes. Bone scintigraphy is more sensitive than radiographs in the detection of acute rib fractures and should be performed in all cases of suspected infant abuse.

Acute Disease↗

PubMed2000

Promoting secure attachment, maternal mood and child health in a vulnerable population: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy of an early home-based intervention on the quality of maternal-infant attachment, maternal mood and child health parameters in a cohort of vulnerable families. METHODOLOGY: A total of 181 families were recruited to the study in the immediate postnatal period on the basis of a self report questionnaire relating to known family vulnerability factors. Families were assigned randomly to intervention (90), or control (91) groups. The intervention group received a series of home visits from a child health nurse (weekly to 6 weeks, fortnightly to 3 months), with a subgroup receiving home based short-term dynamic therapy from a social worker. Parent/family function was assessed at inception and at 4 months by the Parenting Stress Index and the Edinburgh Post Natal Depression Scale. At 4 months the quality of the home environment was assessed, utilizing the Home Observation for Measurement of the Environment Inventory, as were child and family health parameters and satisfaction with the community child health service. RESULTS: At 4 month follow-up, 160 families (80 intervention, 80 control) were available for assessment. The intervention improved family functioning at 4 months. All aspects of the home environment, including the quality of maternal-infant attachment and mothers' relationship with their child, were significantly enhanced. In particular, significant and positive differences were found in parenting with the intervention group feeling less restrictions imposed by the parenting role, greater sense of competence in parenting, greater acceptability of the child, and the child being more likely to provide positive reinforcement to the parent. Early differences in maternal mood were not maintained at 4 months. Various child health parameters were enhanced including immunization status, fewer parent-reported injuries and bruising, and researcher confirmed lack of smoking in the house or around the infant. The families were consistently more satisfied with their community health service. CONCLUSIONS: This form of early home based intervention targeted to vulnerable families promotes an environment conducive for infant mental and general health and hence long-term psychological and physical well-being, and is highly valued by the families who receive it.

Adult↗

PubMed1999

Stressed parents with infants: reassessing physical abuse risk factors.

OBJECTIVE: This study aimed to examine the relationship between a range of potentially adverse psychosocial and demographic characteristics identified in the immediate postpartum period and child physical abuse potential at 7 months. METHOD: Data collected as part of a randomized controlled trial of a nurse home visiting programme for vulnerable families with newborns was used. Women (181) were recruited in the immediate postpartum period. At 7 months, 151 participants were available for evaluation. Potential for child physical abuse was assessed using the Child Abuse Potential (CAP) Inventory. RESULTS: Significant risk indicators identified by univariate analysis were financial stress, elevated Edinburgh Postnatal Depression Scale (EPDS) scores, education level less than 10 years, concern regarding the provision of housing, and domestic violence characterized by verbal and social abuse. There was no association between child abuse potential and sole parenthood, poverty, young maternal age, history of childhood abuse, or psychiatric history. Two variables were found to be of independent significance using a logistic regression model; elevated EPDS and perceived difficulty "making ends meet." CONCLUSIONS: The findings indicate that perceived stress relating to finances, accommodation and relationships in the immediate postpartum period are associated with heightened child physical abuse potential at 7 months. Elevated EPDS in the early postpartum period is also a risk indicator. The outcome of this study suggests that perinatal assessment of child abuse risk is possible and simple and is related to perceived stressors at the time surrounding delivery. This is independent of a range of demographic variables traditionally thought to predict high risk.

Adult↗

PubMed1999

A randomized, controlled trial of nurse home visiting to vulnerable families with newborns.

OBJECTIVE: This project aimed to evaluate the impact of a home visiting programme that targeted families where the child, for environmental reasons, was at great risk of poor health and developmental outcomes. METHODOLOGY: Women in the immediate postpartum period were recruited to a randomized double-blind controlled trial on the basis of self-reported vulnerability factors and were randomly assigned to receive either a structured programme of nurse home visiting, supported by a social worker and paediatrician (n = 90), or assigned to a comparison group receiving standard community child health services (n = 91). Parenting stress and maternal depression were measured at enrollment and at 6 weeks. Preventive health behaviour, service satisfaction and home environment outcomes were tested at 6 weeks, as were child health outcomes. RESULTS: At six weeks, women receiving the home-based programme had significant reductions in postnatal depression screening scores as well as improvements in their experience of the parental role and improvement in the ability to maintain their own identity. Maternal-infant interactions were more likely to be positive, with significantly higher (better) scores in aspects of the home environment related to optimal development in children, particularly maternal-infant secure attachment. Intervention group mothers were significantly more satisfied with the community child health service. CONCLUSIONS: This form of intervention for families is effective in promoting secure maternal-infant attachment, preventing maternal mood disorder and is welcomed by the families receiving it. These findings may predict long-term benefits for the healthy development of children otherwise at risk of a range of poor health and development outcomes.

Analysis of Variance↗

PubMed1998

Vitamin E and lipoic acid, but not vitamin C improve blood oxygenation after high-energy IMPULSE noise (BLAST) exposure.

Exposure to high energy impulse noise (BLAST) caused by explosions, result in structural and functional damage to the hollow organs, especially to the respiratory and auditory systems. Lung damage includes alveolar wall rupture, edema and hemorrhage, and may be fatal. Previous observations at the molecular level using the rat model, suggested that secondary free radical-mediated oxidative stress occurs post exposure resulting in antioxidant depletion and hemoglobin (Hb) oxidation. This study examined whether a short period of pre-exposure supplementation with antioxidants would protect Hb from the effects of BLAST exposure. Six groups of male Sprague-Dawley rats (8/group) were gavaged with 800 IU vitamin E (VE) in 2 ml corn oil, 1000 mg vitamin C (VC) in 2 ml distilled water or 25 mg or (-lipoic acid (LA) in 2 ml corn oil for 3 days. Matched control groups were gavaged with the respective vehicles. On day 4, rats were deeply anesthetized and exposed to a simulated BLAST wave with an average peak pressure of 62 +/- 2 kPa. Rats were euthanized one hour post exposure and blood samples were obtained by cardiac puncture and analyzed using a hemoximeter. Post exposure oxygenation states (HbO2, O2 saturation, and O2 content) were markedly decreased, while reduced-Hb was increased. Supplementation with VE and LA reversed the trend and increased Hb oxygenation, but VC did not. This suggests that a brief dietary loading with pharmacological doses of VE or LA, but not VC shortly before BLAST exposure may be beneficial. Moreover, measurement of blood oxygenation may function as a simple semi-invasive biomarker of BLAST-induced injury applicable to humans.

Animals↗

PubMed1998

Experimental African HEV infection in cynomolgus macaques (Macaca fascicularis).

Experimental infection with hepatitis E virus (HEV) from Africa has not been investigated. Our purpose was to study hepatitis E produced by HEV from Chad (North Africa) and to analyze the genetic sequence of the HEV obtained after animal passage. An HEV-containing fecal sample from Chad was intravenously inoculated in four cynomolgus macaques. When serum Alanine Amino Transferase (ALT) levels rose, open liver biopsy and bile aspiration were performed. In all the monkeys, an ALT rise occurred 25 to 32 days after inoculation and new anti-HEV was detected by Enzyme Immuno Assay (EIA). Hepatic histopathology was consistent with acute viral hepatitis. HEV was detected by polymerase chain reaction (PCR) in bile (3/4 animals) and feces (2/4 animals) and by imunoelectron microscopy (IEM) in the inoculum and one bile specimen. A genetic variant HEV was identified in one monkey. The Chad HEV produced hepatitis E with pathophysiologic and histopathologic findings similar to those observed with HEV from other geographic origins. A genomic variant HEV population was produced after one passage in a macaque.

Alanine Transaminase↗

PubMed1998

The child abuse lottery--will the doctor suspect and report? Physician attitudes towards and reporting of suspected child abuse and neglect.

OBJECTIVE: To assess the responsiveness and attitudes of medical practitioners to the reporting of suspected child abuse or neglect. To determine whether characteristics of the medical practitioner (specialist or generalist, rural or urban based, age since graduation, gender, having children of their own) influenced the responsiveness to reporting. METHOD: A survey of all members of the Australian College of Pediatrics in Queensland (Australia) and pediatric registrars at a tertiary training hospital in Brisbane (n = 124) and a random sample of Queensland general practitioners (n = 100). The survey requested demographic details, responses to three case vignettes suggestive of possible physical abuse or neglect, and details of suspected child abuse or neglect reporting behavior. RESULTS: There were a wide range of responses to the case vignettes, but responses did not vary between specialties. Forty-three percent of all doctors had at some stage considered a case as suspected child abuse or neglect and decided not to report despite a legal mandate to do so. General practitioners were more cautious towards reporting. The reasons for not reporting were multiple but highlighted perceived problems in the services available for the child and family once a report was made. CONCLUSIONS: There is need for continuing education of medical practitioners regarding symptoms and signs of physical abuse and the role of doctors in the multidisciplinary management of child abuse. To some extent children's outcome when presenting to medical practitioners as a result of child abuse or neglect is no better than a lottery, dependent on which doctor they happen to see.

Adult↗

PubMed1998

The sleep patterns of infants and young children with gastro-oesophageal reflux.

OBJECTIVE: Sleep disturbance in gastro-oesophageal reflux disease (GORD) in infants and young children has not been systematically studied nor has this manifestation been compared with population norms. METHODS: Sleep patterns of 102 infants and children aged 1 to 36 months with and without GORD, defined by pH monitoring, were analysed using the same questionnaire as in recent studies of normal sleep behaviour in this age range. Main outcome measures included time taken to settle at night, the number of night time wakenings requiring parental intervention, day time sleep patterns and parents problems with their childs' sleep behaviour. RESULTS: Compared with the population norms (n=3102), those with GORD (n=76) had greater prevalence of night time waking >3/night (50% vs 13% aged 3-12 months; 60% vs 10% aged 12-24 months, P<0.001), requirement of parental intervention (82% vs 55% aged 3-12 months, P<0.05; 92% vs 55% aged 12-24 months, P<0.001), significantly delayed onset of sleeping through the night, and greater prevalence of daytime sleep beyond 24 months. Similar but less striking differences were seen comparing those with (n=76) and without GORD (n=26). CONCLUSIONS: Sleep interruption occurs more frequently in infants and children with GORD than population norms. Objective evaluation of infants and children with sleep disturbance after the age of 3 months may avoid unnecessary over or under diagnosis of GORD. Systematic investigation of the contribution of GORD to sleep disturbance in infants and young children is warranted.

Child, Preschool↗

PubMed1998

Sleep deprivation or postnatal depression in later infancy: separating the chicken from the egg.

OBJECTIVES: To explore the association between maternal distress and depression in the first years of a newborn's life and the child's sleeping behaviour and problems associated with this behaviour. To asses the effectiveness of an outpatient-based individualised behaviour modification programme to modify children's sleep behaviour and to decrease levels of maternal distress and depression. METHOD: Families were referred to an outpatient childhood sleep problems clinic. Intervention consisted of an individualised management programme including recognised modes of child sleep behaviour management ('controlled crying', 'cold turkey,' rewards) together with occasional use of short-term (less than 2 weeks) tapering dose sedating medication for the child. Two months after the initial contact with the clinic, families completed a second questionnaire collating similar data to that collected at time of enrolment. RESULTS: A total of 114 consecutive families referred to the clinic provided initial data. Follow-up questionnaires were returned by 70 (61%). Significant change was recorded in children's sleep parameters including reduction in mean number of night time awakenings (4.1-1.3, P < 0.001), proportion of children requiring longer than 30 min to settle at night (49% to 21%, P < 0.01) and in the proportion of children settling after 8 pm (51% to 33%, P < 0.01). Sleep problem rating on a 0-10 scale decreased from a mean of 8.1-3.1 (P < 0.001). On initial assessment, 40% of mothers had Edinburgh Postnatal Depression Scale (EPNDS) scores greater than 12 (screening cut-off point). At repeat assessment, 4.3% had scores greater than 12. The mean score on the EPNDS fell from 11.2 to 5.8 (P < 0.001). CONCLUSIONS: An outpatient-based individualised approach to modifying children's problematic sleep behaviour using recognised behaviour management techniques is effective. Modification of problematic childhood sleep behaviour is associated with significant improvement in maternal mood. Given the high incidence of childhood sleep problem and diagnosed postnatal depression, it is likely significant numbers of mothers being diagnosed as having postnatal depression are suffering the effects of chronic sleep deprivation. Management of postnatal mood disorder and childhood sleep behaviour must occur with due recognition to their close association.

Adult↗

PubMed1998

Childhood sleep problems: association with prenatal factors and maternal distress/depression.

OBJECTIVE: To determine whether problems with childhood sleep behaviour are associated with either maternal sleep patterns and emotional status during the pregnancy period, or levels of maternal distress and depression during the postnatal period. METHODOLOGY: A case/control comparison study. Cases were families presenting for admissions to a mother/baby hospital in Brisbane with the major presenting problem being the child's sleep behaviour. The control group consisted of families presenting for well child health care to one of four child health centres in suburban Brisbane. Each participating mother provided information by way of a self-report questionnaire on social and demographic variables, children's sleep patterns, maternal emotional adjustment and maternal sleep pattern during the pregnancy, and current problem with child's sleep behaviour. Current level of maternal distress/depression, was measured using the Edinburgh Postnatal Depression Scale. Cases were compared with controls on all these variables. RESULTS: Significant differences were found between groups in childhood sleep parameters, degree of problem related to childhood sleep, maternal sleep variables during the entire pregnancy, and current levels of maternal distress/depression. CONCLUSION: The origins of problematic childhood sleep behaviour may lie in the pregnancy period. Levels of maternal distress and depression are associated with problematic childhood sleep behaviour. The issue of whether childhood sleep problem predisposes to maternal distress/depression needs exploration. Assessment of maternal mood disorder or childhood sleep problems should be comprehensive and involve both the maternal infant dyad and the family network.

Adaptation, Psychological↗

PubMed1997

Launching a family-centered, neighborhood-based human services system: lessons from working the hallways and street corners.

The author describes Contra Costa County's efforts to implement Healthy Families 2000, the County's vision of neighborhood-based, family-centered, comprehensive integrated services in two of the county's unincorporated areas, North Richmond and Bay Point. Contra Costa County is one of six bay area counties, northeast of San Francisco. It has nearly 800,000 residents and is home to some of the wealthiest communities in the state as well as some of the poorest neighborhoods. This article provides a systematic review of the process and a discussion of the operating practices and principles guiding Contra Costa's significant effort to change its service delivery approach, anticipating that this experience might be helpful to others as they develop a neighborhood-based human services partnership with community leaders and residents.

California↗

PubMed1997

A biomechanical study of replacement of the posterior cruciate ligament with a graft. Part 1: Isometry, pre-tension of the graft, and anterior-posterior laxity.

UNLABELLED: Twelve fresh-frozen knee specimens from cadavera were subjected to anterior-posterior laxity testing with 200 newtons of force applied to the tibia; testing was performed before and after a femoral load-cell was connected to a mechanically isolated cylindrical cap of subchondral femoral bone containing the femoral origin of the posterior cruciate ligament. The posterior cruciate ligament then was removed, the proximal end of a thin trial isometer wire was attached to one of four points designated on the femur, and displacement of the distal end of the wire relative to the tibia was measured over a 120-degree range of motion. The potted end of a ten-millimeter-wide bone-patellar ligament-bone graft was centered over the femoral origin of the ligament and attached to the femoral load-cell. Isometry measurements were repeated with the wire attached to the bone block of the free end of the graft in the tibial tunnel. Force was recorded at the load-cell (representing force in the intra-articular portion of the graft) as pre-tension was applied, with use of a calibrated spring-scale, to the tibial end of the graft. A laxity-matched pre-tension of the graft was determined such that the anterior-posterior laxity of the reconstructed knee at 90 degrees of flexion was within one millimeter of the laxity that was measured after installation of the load-cell. Anterior-posterior testing was repeated after insertion of the graft at the laxity-matched pre-tension. The least amount of change in the relative displacement of the trial wire over the 120-degree range of flexion occurred when the wire was attached to the proximal point on the femur (a point on the proximal margin of the femoral origin of the posterior cruciate ligament, midway between the anterior and posterior borders of the ligament). The greatest change in the relative displacement was associated with the anterior point (a point on the anterior margin of the femoral origin of the ligament, midway between the proximal and distal borders). The mean relative displacements of the trial wire when it was attached to a point at the center of the femoral origin of the ligament were not significantly different from the corresponding mean displacements of the distal end of the graft when the proximal end of the graft was centered at this point. At 90 degrees of flexion, the force recorded by the load-cell averaged 64 to 74 per cent of the force applied to the tibial end of the graft. The laxity-matched pre-tension of the graft at 90 degrees of flexion (as recorded by the load-cell) ranged from six to 100 newtons (mean and standard deviation, 43.0 +/- 33.4 newtons). With the numbers available, the mean laxities after insertion of the graft were not significantly different, at any angle of flexion, from the corresponding mean values after installation of the load-cell. CLINICAL RELEVANCE: Isometer readings from a trial wire attached to a point on the femur provided an accurate indication of the change in the length of a graft subsequently centered at that point. Anteriorly placed femoral tunnels should be avoided, as the isometer readings indicated increased tension, with flexion of the knee, in a graft placed in this region. The force in the intra-articular portion of the graft was always less than the force applied to the bone block in the tibial tunnel. Therefore, the femoral end of the graft should be tensioned to avoid frictional losses from the severe bend in the graft as it passes over the posterior tibial plateau. With correct pre-tensioning of a graft, normal anterior-posterior laxity at 0 to 90 degrees of flexion can be restored. However, because of the considerable range in the laxity-matched pre-tensions, we recommend that the pre-tension be greater than forty-three newtons for all patients to ensure that normal laxity is restored.

Aged↗