Attributions, criticism and warmth in mothers of children with intellectual disability and challenging behaviour: a pilot study.

BACKGROUND: Associations between parental expressed emotion (EE) or parental attributions and the problem behaviours of children with intellectual disability (ID) have been explored in ID research. However, a more detailed examination of the attributional model of EE has not been reported. In the present study, we partially replicated and extended research focused on mothers of typically developing children with behaviour problems. METHODS: Twenty-seven mothers of children with ID and behaviour problems aged 4-9 years were interviewed about their most problematic behaviours exhibited by their child, and completed a Five Minute Speech Sample. Interview transcripts and speech samples were coded for maternal EE and spontaneous causal attributions regarding the child's behaviour problems. Data were also collected on maternal well-being, and the child's behaviour problems. RESULTS: Mothers typically made attributions that were internal to the child, controllable by the child, personal to the child and stable for the child. Maternal attributions of being able to control the child's behaviour were associated with high maternal criticism and low warmth. Maternal depression was more strongly associated with the child's behaviour problems when mothers were coded as high in criticism or low in warmth. CONCLUSIONS: Patterns of maternal attributions about their child's behaviour problems and their consequences for maternal well-being and maternal-child relationships require more research attention. Implications for practice are discussed, including the potential for maternal attributions to be incompatible with the focus of positive behaviour supports offered to families.

Breaking strength retention and histologic effects around 1.3-mm. ORTHOSORB polydioxanone absorbable pins at various sites in the rabbit.

Absorbable 1.3-mm polydioxanone (ORTHOSORB) pins were implanted in 75 New Zealand White rabbits in three sites: within the lateral subcutaneous tissue parallel to the femur, down the femoral intramedullary canal, and mediolaterally across the femoral condyles (transcondylar). Pins were harvested at periodic intervals up to 56 and 365 days for mechanical and histologic analyses, respectively. Mechanical analyses were performed by loading the pin in double shear. Histologic analyses were performed on the pin and surrounding tissue. Histologic observations revealed a typical nonspecific foreign-body reaction at all implant sites that resolved at 1 year after resorption of the pin. On histologic examination, there was complete resorption of the pin material in the subcutaneous site by day 182, and there was complete resolution of all response to the pin in six of nine rabbits by day 365. In the intramedullary site, pin material was completely resorbed, based on histologic examination, in five of six rabbits by day 182, and there was complete resolution of the response to the pin in eight of nine rabbits by day 365. The pin material was completely resorbed based on histologic examination of the transcondylar site by day 210, and there was complete resolution of the response to the pin in four of six rabbits by day 270 and in four of nine rabbits by day 365. No enlarged pin tracks or sinus formations were observed in or near the implants sites. The average initial shear strength as 171.4+/ 5.1 MPa, and the breaking strength retention decreased with increasing implantation time. Pins from the subcutaneous regions maintained above 97% of their initial strengths at 28 days, and those from the intramedullary canals maintained above 92%. At later times the strength of the pins implanted in the intramedullary canal decreased more rapidly than those from the subcutaneous region. Overall, the average breaking strength of the subcutaneous pins was significantly greater than that of the intramedullary pins at all time points beyond 14 days. These data indicate that the pins exhibited a strength retention profile sufficient to allow normal healing of bone without enlarged pin tracts, allergic reactions, or sinus formations.

Finite element analysis in the design and characterization of an absorbable cement restrictor.

The benefit of using a cement restrictor to achieve cement pressurization during total hip arthroplasty is well established. An absorbable cement restrictor design has been developed with the use of a finite element model. The non-linear axisymmetric model was used to optimize specific parameters so as to perform within acceptable limits when tested over a specified range of medullary canal sizes. The results achieved from a hybrid experimental/analytical design methodology allowed for a shorter development cycle for the initial size and each additional size in the design family thereafter. The resulting cement restrictor design was compared to and exceeded the performance of currently clinically accepted devices in resisting migration.

Changes in the mechanical properties of patellar tendon preparations of spontaneously diabetic dogs under long-term insulin therapy.

Diabetes mellitus is known to involve a wide range of musculoskeletal disorders including tendon contracture, tenosynovitis, joint stiffness, and osteoporosis. Recent studies with experimentally induced models of diabetes show that insulin therapy mitigates such alterations. These data are from relatively short-term experiments. This manuscript reports the results of tensile failure experiments on the canine patella-patellar tendon-tibia complex from a group of juvenile diabetic animals that received insulin therapy. The duration of the disease was 4-9 yr. The stiffness of the diabetic preparations in a physiological range of loading was approximately 13% greater than controls (P < 0.05). On the other hand, the strength of the tendon preparation from the diabetic population was not different from controls, but the mode of structural failure for controls was by substance and avulsion fractures while the diabetics failed by tensile fracture of the patella.

The effect of site of implantation and animal age on properties of polydioxanone pins.

Absorbable polymeric orthopaedic pins (Orthosorb) of 2.0 mm diameter were implanted at different sites in mature (3.5 kg, > 5 months) and immature (5 weeks old) rabbits (total 36) for 2, 4, and 5 weeks. The sites of implantation were the medullary canal of the femur, muscles of the thigh and subcutaneous tissue of the dorsum. In mature rabbits, 1.3 mm diameter pins were also implanted in the medullary canal of the femur. The shear strength of the pins harvested from the rabbits, was measured at each time period using a fixture that shears the pins into three parts symmetrically about the load axis. In both mature and immature rabbits the rate of degradation in mechanical properties was higher in the medullary canal of bone than in the muscle and in the subcutaneous tissue (p < 0.05). The strength retention was lower in immature than in mature rabbits after 4 and 5 weeks. The 1.3-mm pins had higher initial strength (174.7 +/- 7 MPa), higher strength retention and slower degradation within the medullary canal of femur of mature rabbits as compared to the 2.0-mm pins (157.5 +/- 4.8). DSC and X-ray diffraction results of control and implanted pins showed higher initial crystallinity and a wider range of crystallite size in the 1.3-mm pins. After 5 weeks in vivo, the crystallinity increased indicating degradation within the amorphous phase. The smaller crystallites underwent recrystallization to form larger crystallites. The results indicate that site of implantation and age of recipient influence the degradation and associated effects on mechanical properties of absorbable implants. The size of the implant, though important in determining its properties, should be considered in association with its microstructure, which also plays an important role in determining strength and strength retention of absorbable polymeric systems.

Mechanical properties of the canine patellar tendon: some correlations with age and the content of collagen.

Portions of the patellar tendon (PT) are currently used for autogenous and allogeneic reconstruction of a torn or damaged anterior cruciate ligament (ACL). Age-related changes in the mechanical properties of the PT may influence its use in this reconstruction procedure. Age-dependent changes in the PT were determined in the dog, which is often used to experimentally study this reconstruction. Tensile failure experiments were performed at 100% s-1 on patella-patellar tendon-tibia preparations from dogs aged 0.5-15 yr. The contents of collagen soluble and insoluble in pepsin were also measured at each age. Fifty-nine percent (16/27) of the preparations failed by avulsion at the patella, but neither the failure load nor the mode of failure were a function of age. Failure load and energy were higher for tendon substance failures compared to avulsions of bone from the patella. While a positive, linear correlation was measured between tensile modulus of the PT and age, the slope of regression was not significantly different from zero. The content of total collagen in the PT decreased significantly with age. The content of collagen insoluble in pepsin, however, increased with age and positively correlated with tensile modulus of the tendon. These results are different from those reported for the canine CCL, by others, which degenerates with age. Age-related changes in the mechanical properties of the canine PT are qualitatively similar to earlier, limited data on human patellar tendons.(ABSTRACT TRUNCATED AT 250 WORDS)

A biomechanical comparison of 7-hole 3.5 mm broad and 5-hole 4.5 mm narrow dynamic compression plates.

Seven-hole 3.5 mm broad and 5-hole 4.5 mm narrow dynamic compression plates were applied to paired canine cadaveric tibias in a stable fracture model. Paired tibias were tested to acute failure in rotation and four-point bending, and to fatigue failure in four-point bending. Resistance to screw pullout was measured for three 3.5 mm cortical screws and two 4.5 mm cortical screws inserted in the configurations of the bone plates. All plate-bone systems failed by fracture of the bone through a screw hole. The 3.5 mm plate-bone system was stronger in acute failure in rotation and in four-point bending. There was no difference in stiffness, and no difference in the number of cycles to failure in fatigue testing. Three 3.5 mm screws had greater resistance to pullout than two 4.5 mm screws. Results indicate that the 7-hole 3.5 mm broad dynamic compression plate has a biomechanical advantage over the 5-hole 4.5 mm narrow dynamic compression plate.

Biomechanical and histological observations of the dog patellar tendon after removal of its central one-third.

The use of a central one-third patellar tendon as an autograft for surgical reconstruction of a damaged cruciate ligament is common. Few complications of its use have been reported. However, recent clinical studies indicate that decreased quadriceps strength, decreased range of motion, decreased thigh circumference, and patellofemoral problems can be associated with this procedure. Some of these complications may result from alterations in the biomechanical properties of the remaining patellar tendon. The objective of this study was to examine biomechanically and histologically the fate of the remaining patellar tendon after removal of its central one-third. Three groups of dogs were used for this study. On one knee the central third of the patellar tendon was removed, while the contralateral side was used as a control. One group was immediately euthanized, while the other two groups were euthanized at 3 and 6 months. Control and operated patella-patellar tendon-tibia preparations were harvested and stretched to failure at 100% strain per second. The 3 and 6 month groups had a 10% decrease in length of the operated patellar tendon versus the contralateral control. There was a very significant increase in cross-sectional area of the patellar tendon at 3 months, and a further increase at 6 months. The failure load was 70% of the controls at 3 months and 60% of the controls at 6 months. The stiffness and modulus of the operated tendon within the physiologic range were dramatically reduced to 70% and 33% of controls at 6 months, respectively. These overall results were observed with the central one-third defect closed or left open in surgery.(ABSTRACT TRUNCATED AT 250 WORDS)