[1] Minist Hlth Russian Federat, Nizhny Novgorod Res Inst Traumatol & Orthoped, Verkhne Volzhskaya Naberezhnaya St,18, Nizhnii Novgorod 603155, Russia
[2] City Clin Hosp No 13, Nizhnii Novgorod 603018, Russia
[3] City Clin Hosp No 13, Dept Neurosurg, Nizhnii Novgorod 603018, Russia