Saturday, June 5, 2010

Grow Taller by Diaphysis Microfracture?

We already know it's possible to grow taller by the diaphysis with limb lengthening or some sort of bone stretching in combination with microfracture.  But, the diaphysis contains yellow bone marrow and trabecular bone.  Fractures heal by endochondral ossification so yellow bone marrow must have some sort of stem cell properties.  The problem is that the stem cells in the diaphysis can't get to the hyaline cartilage growth plate line due to being blocked by the endiosteum which divides the cortical bone and the trabecular bone within the diaphysis.  However, there is some research that indicates that trabecular microfracture within the diaphysis can contribute to bone length increase.

Proliferation analysis of the growth plate after diaphyseal midshaft fracture by 5'-bromo-2'-deoxy-uridine.

"Both stimulative and inhibitory growth disturbances may occur after a fracture during the growth period. Chondrocyte proliferation [may lead] to overgrowth. This study investigates the effect of a fracture on the proliferation of chondrocytes at the nearby growth plate and its effect on the contra-lateral leg. Fifty-six 1-month-old Sprague-Dawley rats (weight, 100-120 g) were randomised to either an experimental or a control group. A closed mid-diaphyseal tibial fracture was produced in all animals of the experimental group using a standardised technique. On day 3, 10, 14 and 29 of the experiment, the rats were euthanised and their tibial growth plates were subjected to histological analysis.  Proliferation of chondrocytes [increased] in the growth plates of broken bones during fracture healing. This proliferation peaked on day 3 post-fracture and then reduced gradually until day 29. No increase in the rate of proliferation was observed on the contra-lateral limbs of the animals in the experimental group. Following a diaphyseal fracture of the tibia, the growth plates located next to the fracture react with increased cell proliferation. This proliferation was not observed in the contra-lateral uninjured tibia."

What I don't get is if the fracture occurred at the middle of the shaft then shouldn't both growth plates be equally nearby?  But during development the growth plate is a lot bigger.  If stem cells were released from the trabecular bone they could travel through the blood into the growth plate and differentiate into chondrocytes whereas with a fully developed adult there's a lot smaller growth plate line to head into so the stem cells are less likely to make it there.  Also, during development there's active genetic expression for various chondrocyte growth factors(which we re-activate by loading the articular cartilage during LSJL).  In addition, during development things like the endiosteum are not fully formed and are not as developed hence it being easier for stem cells to get through to that growth plate.

Scientists would have to do tests on diaphyseal microfractures versus full on diaphyseal fractures to know which theory explained bone "overgrowth".  If the bone overgrew during diaphyseal microfracture it would be due to a thinner endiosteum whereas if it only grew during full on diaphyseal fracture it would be due to stem cells traveling up and around.

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