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Muscle regeneration and fiber-type transformation during distraction osteogenesis
P G De Deyne1, K Hayatsu, R Meyer
1Division of Orthopaedic Surgery, Maryland Center for Limb Lengthening and Reconstruction, University of Maryland School of Medicine, Baltimore, USA. pdedeyne@surgery1.umaryland.edu
Summary
Distraction osteogenesis in young rabbits causes muscle fiber changes, mimicking development and muscle overload, without affecting function. This adaptation in the tibialis anterior muscle is crucial for successful bone lengthening outcomes.
Area of Science:
- Biomedical Engineering
- Skeletal Biology
- Muscle Physiology
Background:
- Successful bone lengthening via distraction osteogenesis requires soft tissue adaptation.
- The tibialis anterior muscle's response to distraction osteogenesis is not fully understood.
Purpose of the Study:
- To characterize the adaptation of the tibialis anterior muscle during distraction osteogenesis.
- To investigate the effects of different distraction rates and amounts on muscle adaptation.
- To assess functional integrity of the muscle during and after the procedure.
Main Methods:
- Distraction osteogenesis was performed on skeletally immature rabbits at varying rates (0.7 and 1.4 mm/day) and amounts (15% and 30% lengthening).
- Muscle tissue analysis included myosin heavy chain expression (neonatal and slow types) and immunohistochemistry.
- Electrophysiological methods were used to assess muscle function.
Main Results:
- Increased expression of neonatal and slow myosin heavy chain was observed in the tibialis anterior.
- Neonatal myosin expression was concentrated distally, while slow myosin expression was uniform throughout the muscle.
- No significant changes in myosin expression were noted in the soleus or gastrocnemius muscles.
- Electrophysiology confirmed the tibialis anterior remained functionally intact.
Conclusions:
- Distraction osteogenesis in young animals induces a developmental recapitulation in the tibialis anterior without functional impairment.
- A fiber-type transformation occurs, similar to muscle overloading responses.
- Soft tissue adaptation, particularly in the tibialis anterior, is vital for successful distraction osteogenesis.