Your brother might be suffering from Avascular necrosis,which is a pathology due to increased pressure in femoral head.
In absence of gross joint arthritis and irregularity, first operation for a Avascular necrosis of hip should be core decompression.
In which a drill hole is made inside the femoral head and either a graft(fibula head) or these stem cells can be used, to increase vascularity and union chances.
Next Steps
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Health Tips
In core decompression, native head is preserved.
Stem cell therapy can help .
If it fails, THR is indicated.