Femoral shaft fracture in 265 children: Log-normal correlation with age of speed of healing

Age-related changes of cell outgrowth from rat calvarial and mandibular bone in vitro

“…Ageing reduces the regenerating potential of bone in defects (Nieminen et al, 1981;Skak and Jensen, 1988;Kawai et al, 1997;Hee et al, 2001;Van Damme, 2005). Animal models suggest that 6-week-old rats regain normal bone biomechanics 4 weeks after a fracture, 26-week old rats however, need 10 weeks and 1-year-old rats need more than 6 months (Meyer et al, 2001).…”

“…An age-related decrease in the number of osteogenic progenitor cells seen in animal models (Gosain et al, 2003;Aalami et al, 2004;Lu et al, 2005) and in man (Nieminen et al, 1981;Skak and Jensen, 1988;Hee et al, 2001) may be one of the underlying mechanisms. In vitro findings based on explant cultures from rabbit periosteum showed that the cambium layer as well as the potential of the cells to differentiate into chondrocytes are diminished with increasing age (O'Driscoll et al, 2001).…”

The Effect of Skeletal Maturity on Functional Healing of the Anterior Cruciate Ligament

“…Conventional orthopaedic wisdom is that ''fractures in children heal faster than those in adults,'' and basic science studies in animals and clinical studies in humans appear to support this clinical experience 21,22 . However, basic science studies of partial transection of the anterior cruciate ligament and patellar tendon healing have suggested that the scar formed in skeletally mature animals is actually stronger than that formed in skeletally immature animals 8,23 .…”

Young, adult, and old rats have similar changes in mRNA expression of many skeletal genes after fracture despite delayed healing with age

“…The time required for radiographic union following femoral fracture increases with age in rats, [5][6][7] mice, 8,9 and humans. [10][11][12][13][14][15] While young 6-week-old rats form bone to bridge the fracture gap by 4 weeks after fracture, adult 26-week-old rats require 10 weeks, and older 52-week-old rats need in excess of 26 weeks. 7 Despite this increased time to healing with age, there was no increase in the time of expression of Indian hedgehog or any of the bone morphogenetic proteins in the fracture callus.…”