Endochondral ossification of mandibular condyle , the impact of shock-wave therapy

The growth of the mandibular condyle follows a typical cascade of the endochondral ossification process including proliferation and differentiation of chondrocytes. Extracorporeal shock wave (ESW) effects on the activity of modulation of local regulatory factors leading to neovascularization, differentiation and proliferation of stem cells have been reported. This study is aimed to investigate the impact of ESW on the growth rate and development of the mandibular condyle chondrocytes.

Method:

Mandibular condyle chondrocytes of neonatal mice were isolated and cultured to confluence. The cultures were exposed to a single application of 500 unfocused impulses of ESW at an energy flux density of 0.05mj/mm².  Proliferation and differentiation rates were measured by the level of radiolabeled thymidine incorporation into DNA and the effect of ESW on the cell population in the MTT cell proliferation assay. The expression of certain local cytokines (e.g. IGF1, IHH, PTHrP) was measured by immunohistochemistry.      

Result:

The number of viable cells increased seven and ten days after application of ESW (30% and 121%, respectively) compared to untreated controls. The proliferation rate increased in treated cells compared to untreated controls in intervals of 24 hours (30%) and 48 hours (7%). Treated cells expressed higher levels of PTHrP and IGF1, two and seven days after ESW application compared to untreated controls.

Conclusion:

Experiments seem to support our hypothesis that shock waves might positively modulate skeletal growth.

We could show that shock wave increases proliferation rate.

Immunhistochemiacal studies indicated that this stimulative effect might be attributed to the increase in PTHRP expressing, known for its positive modulatory impact on cartilage cells proliferation.