Even if you could grow taller via your articular cartilage, it’s likely that the periosteum would constrain additional growth.  Note the studies that shows that articular cartilage longitudinal growth can continue in bones without periosteum such as the fingers.

By mimicing the effects of the bite-jumping device on the mandible and the way it increases growth in that region it could be possible to increase in the same way in the fingers by pulling on them.

Repeated mechanical loading enhances the expression of Indian hedgehog in condylar cartilage.

“Indian hedgehog (Ihh) acts as a mechanotransduction mediator that converts mechanical strain into cellular proliferation and cartilage formation in mandibular condylar cartilage{But could Ihh act as a signal to induce mesenchymal stem cell differentiation into chondrocytes?  Ihh has been shown in some instances to be a chondrogenic inducer of mesenchymal stem cells.}. The aim of this study was to examine the effect of repeated mechanical strain on the level of expression of Ihh and type II collagen mRNA in condylar growth. Two hundred and eighty 35 days old Sprague-Dawley rats were divided into 10 experimental and 10 control groups. Repeated mechanical loading was applied by advancing the mandible in a stepwise manner by fitting a stepwise bite jumping appliance{Bite jumping devices have been shown to induce adaptations in 135 day old rats(almost five months old), this bite jumping device was explained as reactivating endochondral ossification in the old rat condyle}. Animals were sacrificed together with their matched controls on 10 different time points. Total RNA was extracted from condylar cartilage immediately after dissection. Ihh and type II collagen mRNA was quantified. In the experimental group, Ihh mRNA increased significantly on experimental day 7. Upon the second advancement, another peak was elicited 7 days later. Type II collagen showed a significant increase on days 21 and 44 of advancement. Mechanical loading in a repeated manner, triggers the expression of Ihh which in turn increases the number of replicating mesenchymal cells as well as the amount of the cartilage formed. Taken together these events increase condylar growth.”

Here’s what a bite jumping appliance looks like:

Here’s more info on the bite jumping device.  This device seem like it would place a distraction force on the bone and cartilage.

“Mandibular forward positioning led to changes in the biophysical environment that caused deformation of the mesenchymal cells and other cells in the extra-cellular matrix. Thus create strain alignment that causes deformation of the cytoskeleton of these cells and trigger the expression of Ihh. The expression of Ihh elicited by mechanical loading of the mandibular joint promoted mesenchymal cell proliferation and initiated a cascade of cellular and molecular responses that led to condylar growth”

“Mechanical stress stimulated Ihh expression in chondrocytes in vitro by 18-fold. Over expression of Ihh in transgenic mice led to an increase in the number of replicating chondrocytes in the growth plate”

“the number of replicating mesenchymal cells in the condyle directly impacts the growth potential of the condyle. Furthermore, the number of replicating chondrocytes impacts the amount of cartilage to be formed and subsequently influences condylar growth because cartilage acts as the template onto which bone will form. Therefore, over expression of Ihh in the condylar cartilage in response to mechanical loading could result in enhanced condylar growth. ”

“Ihh mRNA expression showed a decrease with age during natural growth. Forward mandibular positioning led to a significant increase of Ihh mRNA, with the peak identified on day 7 and dropped to control level after 14 days of appliance wearing. The peak increment corresponded to a fold change of 5 in the stepwise advancement group. ”

“Upon the second advancement on experimental day 30, Ihh mRNA showed a significant increase on experimental day 33 and reached another peak on experimental day 37, which has a corresponding fold change of 12.5. After the peak, the level of expression started to decrease again to the normal level. ”

“In the experimental group, collagen II mRNA started to increase on days 14. Although the critical values were statistically insignificant when compared with the control, a greater amount of mRNA was detected on experimental days 14 and 21. The fold change identified was 2.5 and 2.8 respectively.  The second advancement on days 30 led to a significant increase in type II collagen mRNA, which reached the peak on days 51 with a fold change of 21.8. The amounts of mRNA detected on experimental days 44 and 51 were significant when compared with natural growth. ”

The first mandibular advancement was by 2mm.  It would be interesting to measure any temporary change in leg length during LSJL.  The second advancement was also by 2mm.

Factors regulating condylar cartilage growth under repeated load application.

“280 Sprague-Dawley rats were used in this experiment. The animals were randomly allocated into experimental and control groups. Repeated mechanical loading was applied through a bite-jumping device in the experimental group. The experimental animals were sacrificed on 10 different time points together with the matched control. Total RNA was extracted from the mandibular condylar cartilage for PTHrP and SOX9 genes quantification using real-time RTPCR. PTHrP expression was increased and reached a peak level on the seventh day after mechanical loading was given. Repeated mechanical loading triggered a significant increase of PTHrP expression leading to another peak increment. The expression of SOX9 was highly correlated with the PTHrP expression, and its pattern of expression was similar to that of PTHrP after repeated mechanical loading. In conclusions, repeated mechanical loading on the condyle triggers the expression of PTHrP and SOX9, which in turn promotes condylar cartilage growth.”

“The set-up involves an intra-oral [bite-jumping] device that positions the mandible forward, therefore, generating tension at the condyle and the glenoid fossa. ”

“t mechanical loading led to a significant increase in the expression of PTHrP, which delayed cartilage cells maturation and endowed the condyle with more potential to buildup cartilage. This increase in PTHrP was associated with the increase of new chondrocyte populations. Furthermore, it was documented that PTHrP up-regulated SOX9 transcription, which has been shown to promote differentiation of mesenchymal cells into chondroblasts in the mandibular condyle. It is convincible that repeated mechanical load applications through mandibular advancement in a stepwise manner could re-trigger the expression of these factors and lead to further growth.“<-there does seem to be periosteum in the mandible so it could mean regions with periosteum can be stretched via increased articular cartilage growth.

“PTHrP also up-regulates the expression of SOX9, which in turn acts upon the mesenchymal cells, and induces their differentiation into chondrogenic cells. ”

Note that some bones you can pull thereby immediately increasing the length of the skeleton examples include the wrist, fingers, and jaw.  Pull your finger and make it instantly longer but this seems far more difficult with the elbows and knees but perhaps still possible.

This would be a possible experiment to do on a finger.  There could be a device that pulls the finger away from the hand.  Would it be safe and healthy to the hand to do this for a long period of time?  There’s already a multitude of anecdotal evidence of intermittant tensile on the hand via knuckle cracking.  Although that could be more of a bending force rather than a pure longitudinal stretching one.  But I know that some people crack their knuckles by pulling them.

Does anyone have any anecdotal advancement of people with longer hands due to cracking their knuckles by pulling on their fingers?

In addition, any exercise like deadlifts and farmer’s walk would put a pulling force on the arms.  Does anyone have any anecdotal evidence of people getting longer arms by doing farmer’s walks?