Effect of distraction rate and consolidation period on bone density following mandibular osteodistraction in rats.

The high cost of large animal protocols has limited the study of distraction osteogenesis (DO) in the craniofacial region. This study was designed to characterise a rat model for DO with regard to distraction rate and consolidation period. Unilateral mandibular distraction was performed on 129 male Sprague-Dawley rats using an osteotomy from the sigmoid notch to the inferior border of mandible. After a 3-day latency, 12 groups of 8-9 rats underwent distraction for 5 days at four different rates (0, 0.2, 0.4, 0.6mm per day), with three different post-osteotomy sacrifice times (10, 24, and 38 days) and four final predicted distraction lengths (0, 1, 2, and 3mm). Another four groups of rats (N=8 per group) were sacrificed 6 days post-osteotomy, resulting in distraction for 3 days with a predicted distraction length of 0, 0.6, 1.2, 1.8mm. Changes in mandibular morphology were measured from radiographs of disarticluated hemimandibles. The bone density of the regenerate and control sites was measured using microdensitometry calibrated with an epoxy stepwedge. Distraction linearly increased mandibular length, distraction gap width and the area of the distraction gap (P<0.00005). Mandibular length increased by 0.394 mm per distraction rate. Gap width and area increased by 0.67 and 5.8mm(2) per distraction rate, respectively. The increase in length represents only 39.4% of what was predicted, suggesting that compensatory alteration in condylar or mandibular morphology may have occurred. This speculation was further supported by the finding that mandibular length, measured without the condylar landmark, was 53.8% of predicted. During DO and early consolidation, the measures of bone density in the regenerates decreased compared to control for all groups. Thereafter, bone density in the regenerates generally increased in all groups until day 24 (P<0.01), obtaining levels that were comparable to the unoperated side. At both rostral and caudal sites adjacent to the osteotomies, measures of bone density were enhanced over control in all groups, with the rostral site also showing significant increases over time in the sham and the highest distraction groups (P<0.008 and P<0.014). We conclude that this rat model for mandibular distraction osteogenesis provides bone density changes that are consistent with those reported using larger animal protocols.

Development and validation of the workshop behavior checklist: a scale for assessing work performance of people with severe mental illness.

The Workshop Behavior Checklist is a standardized assessment instrument to assess the work performance of people with severe mental illness using the situational assessment approach. It is modified from the Behavior Identification Form developed by the Material Development Center. The modification process was conducted by enlisting input from mental health professionals (n = 150) and potential employers of discharged patients with mental illness (n = 31) by questionnaires specially designed for this purpose. The results of these questionnaires were then analyzed by an expert panel consisting of 10 therapists and one psychiatrist working in relevant fields. Altogether 14 items in general behaviors, vocational behaviors, and social behaviors were selected. In addition, a new version of the checklist together with its rating guidelines were designed. Exploratory factor analysis (n = 112) shows that all 14 items fit well into a four-factor model explaining 67.2% of total variance, which is in line with the original design of the revised checklist. Cronbach alpha analysis shows that the revised checklist has acceptable to very good internal consistency (.51 to .84) and intraclass correlation coefficients indicate that it has good to excellent inter-rater (.57 to .81) and test-retest (.86 to .94) reliability. Clinical implications and further research are discussed.

Predictors of post-hospital employment status for psychiatric patients in Hong Kong: from perceptions of rehabilitation professionals to empirical evidence.

Fifty participants with mental illness and a concrete discharge plan were selected from two mental hospitals in Hong Kong and assessed on their Psychosocial support by the Chinese Version of the Significant Others Scale, social vocational competence using the Workshop Behavior Checklist and the Vocational Social Skills Scale, medical history, work history, and demographic variables. At three months after discharge, the employed participants (n = 12) were shown to have better psychosocial support and social vocational competence than the unemployed participants (n = 24) by univariate comparison. The employed and unemployed participants did not differ in their medical and work history, and demographic variables. Implications of the results for rehabilitation programming are discussed.