The effect of repeated sympathetic blocks on bone growth
Cengiz Yılmaz1, Metin M Eskandari1, Şebnem Atıcı2, Necat Yılmaz3, Savaş Aktaş3
1Mersin Üniversitesi Tıp Fakültesi, Ortopedi ve Travmatoloji Anabilim Dalı, Mersin, Türkiye
2Mersin Üniversitesi Tıp Fakültesi, Anesteziyoloji ve Reanimasyon Anabilim Dalı, Mersin, Türkiye
3Mersin Üniversitesi Tıp Fakültesi, Histoloji ve Embriyoloji Anabilim Dalı, Mersin, Türkiye
Keywords: Autonomic nerve block; disease models, animal; fractures; growth plate; leg length inequality/etiology; rats; regional blood flow; sympathectomy.
Abstract
Objectives: Relative overgrowth of the extremity following fractures of the long bones is a well-known complication in children. It is thought to be induced by the stimulating effect of fracture hyperemia on the growth plate. This study sought to determine whether increased blood flow in the lower extremity by repeated sympathetic blocks would result in overgrowth. Materials and methods: Twenty 21-day old Sprague- Dawley rats with a mean weight of 50 g were divided into two groups equal in size. The experimental group was applied unilateral lumbar sympathetic blocks once daily between the 24th and the 75th days. Increase in the blood flow was confirmed by weekly temperature measurements of the lower extremities. The control animals remained untreated. At the end of the experiment, all animals were sacrificed, and all tibias and femurs were excised to measure their lengths and to assess the growth plate, proliferative zone, and endosteal vasculature histologically.
Results: The two groups did not differ significantly with respect to pre- and post-treatment weights (p>0.05). A mean of 0.4 °C increase (range 0.3 to 0.6 °C) was documented in the affected extremities following injections. The lengths of the femurs and tibias did not differ significantly compared to the contralateral and control counterparts (p>0.05). Histologic measurements yielded similar results with respect to thickness of the growth plate and proliferative zone, and the number of endosteal vessels (p>0.05).
Conclusion: Our results do not corroborate the notion that relative extremity overgrowth following fractures of the long bones is induced by an increase in the blood flow.