Comparison of Epiphyseal Distraction versus Lateral Joint Loading

Previously, I've written about epiphyseal distraction before and how it was found to only increase growth rate and not actually increase "final" adult height.  If the slides of epiphyseal distraction versus slides of rats under LSJL were compared, we could see if there were any differences like signs of mesenchymal stem cell recruitment.  And if you look at Slide B, you can see tiny white cells coming down from the bone into the cartilage. 

I asked Hiroki Yokota about it and he said the results are consistent throughout all mice. "This is a mouse study and the images are representative.  We conducted histomorphometry (measurements of thickness, #cells, etc.) and statistical tests.  Therefore, the results are evidence based and statistically significant." One thing I've noticed with inquiring experimenters is that they are willing to answer questions about experiment methodology but aren't willing to offer their opinions as to conclusions.  I can understand why for fear of being quoted for their opinion to use the authority of their research status.

All the slides are from the study: "Limb Lengthening by Distraction of the Epiphyseal Plate: A comparison of two techniques in the rabbit."  The study explains epiphyseal distraction: "[The method] of distracting the epiphyseal plate employs smaller forces and/or a slow rate of distraction with the intention of inducing an increase in the activity of the growth plate without causing either fracture or gap. Thus the functional integrity of the plate is maintained until the end of the physiological growth period. In 1979 De Bastiani, Aldegheri and Renzi Brivio introduced the term chondrodiatasis to describe this slow, controlled and symmetrical distraction of the epiphyseal plate without fracture or rupture."

"Group 2: chondrodiatasis. After 7 and 14 days of distraction, an increase in the height of the growth plate was observed, but the line of the growth cartilage was regular (Fig. 6). The bridging cartilage appeared to be slightly hyperplastic with modest changes in the columnar architecture limited to a few points in the epiphyseal plate.  There was no evidence of detachment of the epiphyseal nucleus, nor of any haemorrhage (Fig. 7).

By day 28, at the end of the period of distraction, the lengthened portion was occupied by ossification tissue
similar in appearance to that of the metaphyseal bone of the control femur. The appearance was not uniform,
because of brownish zones which were areas of tissue undergoing ossification. The line of the cartilage showed normal morphology, but at some points it was markedly thicker. At the periphery of the plate there was an increase in the thickness of the periosteum without gaps in the perichondrium.
 
The bridging cartilage in the zones of increased thickness displayed marked hyperplasia and hypertrophy, with some disorganisation of the columnar structure but no evidence of cellular damage (Figs 8 to I I).  Histological specimens taken on day 50 and day 70 showed an active epiphyseal plate which had returned to normal thickness (Fig. 12). Cellular morphology confirmed the normal organisation of the growth plate and adjacent elements, matching that of the control limb[The control limb was one undergoing distraction osteogenesis in the epiphysis]."




The growth plate 7 days after performing epiphyseal distraction.  Can't see the incoming cells like in LSJL.


28 days after epiphyseal distraction.  The blue line is the hyaline cartilage growth plate line. The red looks like blood flow but the study claimed no sign of hemorrhage.  Blood flow is very anabolic though!

So, evidence of a hyaline cartilage growth plate line after "fusion" and differences between LSJL and epiphyseal distraction.

Here's a normal growth plate:


Here's the "fused" bone after distraction osteogenesis:


The blue line is still there.  The idea behind LSJL is to get stem cells or periosteal progenitor cells to this blue region and then in there the stem cells will undergo differentiation into chondrocytes and endochondral ossification will begin.  Here's what happened when the performed distraction osteogenesis on the growth plate cartilage:

The parts of the cartilage that turned into bone remarkably correlates with the blood splatters.