Understanding Dislocation after Total Hip Replacement

Total hip replacement (THR) surgeries have become fairly common and very successful. Still, some patients have problems with the new joint dislocating. Replacement surgeries that enter the hip joint from the back (the posterior approach) seem to have more problems with dislocation than those that enter from the front (the anterior approach).

These researchers studied different posterior techniques in hip joints taken from cadavers (bodies preserved for study). The researchers tested the range of motion in a hip without a replacement joint. Range of motion was also tested in hips that had THR done through the posterior approach. The researchers tested motion of the THR with different degrees of repair done to the joint capsule and surrounding tendons and muscles. The tests tried to force the joint to dislocate.

Results showed that the posterior approach with repair of the joint capsule and surrounding tissues was the hardest to dislocate. The repaired tissues held the new joint most securely in position. Even when a dislocation was forced, the artificial joint itself did not fail. The easiest THR hip to dislocate was when the joint had to be opened up during the surgery without repair of the joint capsule.