The heterogeneous mechanical properties of adolescent growth plate cartilage: A study in rabbit.

The growth plate is a cartilaginous tissue that functions to lengthen bones in children. When fractured, however, the growth plate can lose this critical function. Our understanding of growth plate fracture and mechanobiology is currently hindered by sparse information on the growth plate's microscale spatial gradients in mechanical properties. In this study, we performed microindentation across the proximal tibia growth plate of 9-week-old New Zealand White rabbits (n = 15) to characterize spatial variations in mechanical properties using linear elastic and nonlinear poroelastic material models. Mean indentation results for Hertz reduced modulus ranged from 380 to 690 kPa, with a peak in the upper hypertrophic zone and significant differences (p < 0.05) between neighboring zones. Using a subset of these animals (n = 7), we characterized zonal structure and extracellular matrix content of the growth plate through confocal fluorescent microscopy and Raman spectroscopy mapping. Comparison between mechanical properties and matrix content across the growth plate showed that proteoglycan content correlated with compressive modulus. This study is the first to measure poroelastic mechanical properties from microindentation across growth plate cartilage and to discern differing mechanical properties between the upper and lower hypertrophic zones. This latter finding may explain the location of typical growth plate fractures. The spatial variation in our reported mechanical properties emphasize the heterogeneous structure of the growth plate which is important to inform future regenerative implant design and mechanobiological models.

Paediatric spinal fusion surgery and the transition to home-based care: provider expectations and carer experiences.

There are more than 12 million children with special healthcare needs (CSHCNs) in the United States, many of whom require specialised health-care to treat chronic physical and developmental conditions. This study is a qualitative investigation of programme, surgical and at-home recovery experiences among CSHCNs and their family carers who participated in a spine surgical care programme at a paediatric hospital in the Western United States. The programme is designed to manage increased surgical risk and the transition of care from hospital to home for children with severe scoliosis undergoing spinal fusion surgery. We conducted 30 semi-structured in-depth interviews with 14 surgical team members and 16 family carers of children who had programme evaluations and spinal surgeries in 2006. Data were collected in 2008 and 2009 in hospital or at home locations to gather programme participation feedback from families and inform the adequacy of programme support to families during at-home recovery. Data were analysed by reflexive team and content analysis methodologies. Results showed the programme was effective at improving preoperative surgical evaluation and helping families to anticipate some aspects of the surgical experience and hospital discharge. However, the impact of spinal fusion surgery and the subsequent transition to home-based care was profoundly emotional for patients and their carers. Our data indicate that programme providers underestimated the extent of emotional trauma experienced by patients and families, particularly during the at-home recovery process. The data also suggest meaningful differences in providers' and carers' expectations for surgery. Carers' disappointment with their recovery experiences and the perceived lack of post-discharge support impacted their interpretations of and perspectives on their surgical experience. Implications of this research for surgical care programmes include the need for assessment and provision of support for physical, social, and emotional burdens experienced by patients and carers at pre-surgical, surgical and at-home recovery phases.

Comparing reliability and validity of pediatric instruments for measuring health and well-being of children with spastic cerebral palsy.

This study sought to examine the reliability and validity of three generic instruments for measuring the health of children with cerebral palsy (CP) and to compare them with a disease-specific measure, the Gross Motor Function Measure (GMFM). The Pediatric Evaluation and Disability Inventory (PEDI), the Pediatric Outcomes Data Collection Instrument (PODCI), and the Child Health Questionnaire (CHQ) were completed by the primary caregivers of 115 young children with spastic CP. The GMFM was administered to the children. The mean age of the sample was 5 years 8 months (range 3:1 to 10:4) and consisted of more males (58%) than females. The PEDI scales demonstrated higher internal consistency than the PODCI and CHQ scales. In comparison with the GMFM, the PODCI transfer and mobility scale (relative validity, 62%) and the PEDI mobility scale (relative validity, 53%) detected the most significant health differences between children with hemiplegia, diplegia, and quadriplegia. The PEDI social function scale detected the largest differences in cognitive function between children with an IQ of less than 70 compared with those with an IQ of 70 or greater. The reliability and validity of these different instruments varied significantly in this patient population.