Extracorporeal shock wave therapy in early osteonecrosis of the femoral head: prospective clinical study with long-term follow-up. - Vulpiani MC; Vetrano M; Trischitta D; Scarcello L; Chizzi F; Argento G; Saraceni VM; Maffulli N; Ferretti A (Archives of Orthopaedic & Trauma Surgery, 2012)