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Body Systems: The Basics
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The body has two basic bone types: cortical and trabecular bone. Cortical bone is structurally strong, dense, and found near bone surfaces. Trabecular bone is generally interior and has a spongy lattice form which holds some of the blood forming bone marrow. The long bones in the arms and legs are primarily cortical bone with areas of trabecular bone near the joint surfaces. At birth, infants’ skeletons are composed of bone and cartilage (a resilient, firm connective tissue) that will be replaced with bone as the child develops. Areas of cartilage near the ends of the bones, known as growth plates, allow the bony skeleton to expand throughout childhood and into adolescence. Bone types, a long bone example, and bone maturation are illustrated in Figure 2.3. Some areas of the adult skeleton are made of cartilage. Feel the tip of your nose. You will notice that it is quite flexible compared to the bony bridge of your nose. Cartilage in your nose supplies flexibility. Cartilage can also provide a cushion where bone meets bone in a joint. Ligaments are strong bands of connective tissue that link bones across joints.
Articular Cartilage Development
Published in Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi, Articular Cartilage, 2017
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi
It is the growth plate cartilage that determines the longitudinal growth of long bones. The chondrocytes of the growth plate have characteristic stages of differentiation and proliferation by region (as diagrammed in Figure 2.12). During postnatal growth, the action of proliferating and differentiating chondrocytes increases the bone length through interstitial growth. Shortly before birth, a secondary ossification center will form at the epiphysis of the cartilage anlage, forming the epiphyseal plate. This will be replaced with bone as the organism ages, until skeletal maturation, usually in the mid-20s in humans. Endochondral ossification of the epiphyseal plate (growth plate) may resemble the stages of matrix destruction associated with osteoarthritis (Dreier 2010), as discussed in Section 3.1.3. Many of the experiments determining signaling pathways in chondrocyte differentiation and development derive from studies in mouse mutations, as disruption of genetic components commonly presents as easily identifiable growth retardation phenotypes (e.g., stunted limbs and dwarfism) (Kronenberg 2003).
Upper extremity injuries
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Ronald F. Zernicke, William C. Whiting, Sarah L. Manske
Loading history may be the most relevant factor to the discussion of ulnar variance and wrist injury mechanisms (De Smet et al., 1994). In gymnastics, for example, with pommel horse or tumbling, the wrist is subject to considerable compressive loads. The radius receives approximately 80 per cent of the load. In a skeletally immature individual, the repetitive compressive loading can cause premature closure of the radial growth plate. Continued ulnar growth would create positive ulnar variance, with potential ulnar impact syndrome and degeneration of the triangular fibrocartilage and ulnar carpus. While wrist pain is common in gymnasts, ulnar variance itself is not associated with wrist pain or radiographically defined injury in the distal radius (DiFiori et al., 2002).
Medical devices and the pediatric population – a head-to-toe approach
Published in Expert Review of Medical Devices, 2019
Joy H. Samuels-Reid, Judith U. Cope
When using medical devices in children, it is important to consider the dynamic changes related to musculoskeletal growth and development. Bone age is more important than chronological age in determining future growth. During rapid growth spurts, changes in skeletal growth may affect the spine and its normal curvatures. For instance, most adolescents do not achieve complete skeletal maturity until 18 to 20 years of age. Differences are most evident in the growing spine, stages of epiphyseal closure and growth plate development. During childhood and adolescence, growth plates may open and close at different rates and vary between boys and girls. Ideally, device considerations in pediatric subpopulations will take into account differences in bone density and the strength of ligaments. All of these may impact medical devices used for orthopedic management and surgical interventions in the pediatric population. Orthopedic medical devices such as screws and plates need to be of varying sizes for the growing child. It is important that proper medical and surgical pediatric-specific instrumentation recognize the differences between children and adults[17].