RESUMEN
Osteonecrosis of the femoral head (ONFH) can cause femoral head depression and cortical discontinuity. Treatment for ONFH remains challenging. We performed botulinum toxin type A injection to psoas major muscle in five patients with radiological femoral head collapse (Association Research Circulation Osseus classification stage III) who were non-responsive after two years of conservative treatment (tramadol 200 mg/day, mefenamic acid 1,000 mg/day). At two weeks after the procedure, their mean hip pain was decreased from 88 ± 0.4/100 mm to 22 ± 0.4/100 mm based on visual analogue scale (VAS). The pain was maintained at a minimum of 20/100 mm and a maximum of 30/100 mm in VAS for at least six weeks after the procedure. These values were mean ± SD. These patients were followed-up for 6 months. There was no exacerbation of pain from repeated (three times) botulinum toxin type A injection to the psoas major muscle.