The present study evaluates the effect of XCEL-MT-OSTEO-ALPHA in osteonecrosis of the femoral head in comparison to the standard treatment of isolated core decompression. XCEL-MT-OSTEO-ALPHA is a tissue engineering product composed by "ex-vivo" expanded autologous mesenchymal stem cells fixed in allogenic bone tissue. The working hypothesis proposes that the tissue engineering is a valid and useful technique to achieve bone regeneration, avoiding the progression to collapse of the femoral head.

Prospective, open-label with blinded assessor, randomized, parallel, single-dose phase I-II clinical trial in which 24 patients affected with osteonecrosis of the femoral head ARCO grade I or II will enter the trial with the primary objective of assessing the feasibility and safety of "ex-vivo" expanded autologous mesenchymal stem cells fixed in allogenic bone tissue in osteonecrosis of the femoral head. Secondary objectives are to assess the efficacy of the implantation by imaging (magnetic resonance imaging) and clinical questionnaires (pain by visual analogue scale, quality of life by SF-36 and WOMAC Index). Patients will be randomized to one of the two treatment arms (core decompression and the tissue engineering product composed by "ex-vivo" expanded autologous mesenchymal stem cells fixed in allogenic bone tissue or the standard treatment of isolated core decompression). Thereafter, patients will be followed for 12 months.