Detrimental effects of overstuffing or understuffing with a radial head replacement in the medial collateral-ligament deficient elbow

BACKGROUND: Comminuted radial head fractures associated with an injury of the medial collateral ligament can be treated with a radial head implant. We hypothesized that lengthening and shortening of the radial neck would alter the kinematics and the pressure through the radiocapitellar joint in the medial collateral ligament-deficient elbow. METHODS: The effects of lengthening (2.5 and 5 mm) and shortening (2.5 and 5 mm) of the radial neck were assessed in six human cadaveric upper extremities in which the medial collateral ligament had been surgically released. The three-dimensional spatial orientation of the ulna was recorded during simulated active motion from extension to flexion. Total varus-valgus laxity and ulnar rotation were measured. Radiocapitellar joint pressure was assessed with use of pressure-sensitive film. RESULTS: Radial neck lengthening or shortening of >/=2.5 mm significantly changed the kinematics in the medial collateral ligament-deficient elbow. Lengthening caused a significant decrease (p < 0.05) in varus-valgus laxity and ulnar rotation (p < 0.05), with the ulna tracking in varus and external rotation. Shortening caused a significant increase in varus-valgus laxity (p < 0.05) and ulnar rotation (p < 0.05), with the ulna tracking in valgus and internal rotation. The pressure on the radiocapitellar joint was significantly increased after 2.5 mm of lengthening. CONCLUSIONS: This study suggests that accurate restoration of radial length is important and that axial understuffing or overstuffing of the radiohumeral joint by >/=2.5 mm alters both elbow kinematics and radiocapitellar pressure. CLINICAL RELEVANCE: This in vitro cadaver study indicates that a radial head replacement should be performed with the same level of concern for accuracy and reproducibility of component position and orientation as is appropriate with any other prosthesis.     

Level of family dysfunction and genetic influences on smoking in women

BACKGROUND: An adoption study of alcoholism suggests that in women, the impact of genetic risk factors become greater in the presence of conflict in the family of origin. Is the same true for cigarette smoking (CS)? METHOD: We obtained, in a sample of 1676 twins from female female twin pairs from a population-based register, a measure of maximum lifetime CS (divided into six ordinal categories) and family dysfunction (FD) assessed as the mean report of up to four informants (twin, co-twin, mother, father). Statistical analysis was conducted by traditional regression analysis and a moderator structural equation twin model using the computer program Mx. RESULTS: With increasing levels of FD, maximum CS increased substantially while correlations for CS in monozygotic (MZ) and dizygotic (DZ) twins decreased modestly. Regression analyses demonstrated reduced twin-pair resemblance for CS with increasing levels of FD. The best-fit structural equation model found high levels of heritability for CS and no evidence for a role of shared environment. With increasing levels of FD, the proportion of variance in CS due to genetic factors (i.e. heritability) decreased while that due to unique environmental effects increased. CONCLUSIONS: Several different statistical methods suggested that, contrary to prediction, heritability of CS decreased rather than increased with higher levels of dysfunction in the family of origin. The hypothesis that genetic effects for psychiatric and drug-use disorders become stronger in more adverse environments is not universally true.     

Therapeutic limit setting and six-month outcomes in a Veterans Affairs assertive community treatment program

OBJECTIVE: This study examined the relationship of limit-setting interventions and six-month outcomes in assertive community treatment. METHODS: Case managers from 40 Veterans Affairs assertive community treatment teams at 40 different sites documented their use of 25 limit-setting activities with 1564 clients during the first six months of treatment. Five scales were constructed representing different types of limit-setting activities: withholding certain types of assistance until the client curtailed certain behaviors; behavioral contracting in which specific goals were identified and linked to reinforcers if the goals were achieved; invocation of external authorities, such as a probation officer; seeking a declaration of incompetence to manage funds or initiation of a request for a payee; and forced hospitalization through civil commitment. Structured interviews conducted at baseline and six months documented changes in clinical status and community adjustment. Multiple regression analysis was used to examine the relationship between limit-setting interventions and outcomes at both the level of the individual client and at the level of the team, adjusting for potentially confounding baseline client characteristics. RESULTS: All five measures of specific limit-setting activities were associated with poorer outcomes on four to six of the eight outcome measures. The site-level comparison of outcomes showed more violent behavior at sites that made more extensive use of these interventions but also greater employment. CONCLUSIONS: After the analysis controlled for potentially confounding factors, clients exposed to limit-setting interventions had poorer outcomes than others on many measures, suggesting that within the limits of a nonexperimental study, such interventions do not appear to prevent adverse outcomes.     

Will haplotype maps be useful for finding genes?

From its introduction into the literature, the idea of haplotype map-based linkage disequilibrium (LD) studies has been the subject of disputes. These queries involve the extent to which the haplotype blocks exist, the validity of fundamental concepts such as the recombination hotspot, and the application of this idea in the form of the HapMap project. In this article, we review the relevant literature to evaluate the potential importance of haplotype maps for psychiatric genetics. We first take a closer look at the nature of haplotype blocks and then address the impact of block definitions and methodological factors, such as single-nucleotide polymorphism density and sample size, on findings from haplotype block studies. After distinguishing between two types of haplotype map-based LD studies, we discuss the importance of the recombination hotspot and the nature of the disease mutations affecting complex traits. In the final section, we summarize our main conclusions and comment on the usefulness of haplotype maps for finding genes.