The tensor fascia lata and gluteus medius turn the thigh bone inward, balancing the turning-out force of the gluteus maximus.

MRI after THA shows partial disruptions of the gluteus medius, with mucoid signal alterations and fatty degeneration even in asymptomatic patients.

The gluteus medius on the outside of the pelvis and the adductor group on the inside of the thigh balance the pelvis from the outside to the inside.