The Role of Stress Shielding in Hip Replacement

Metal on metal hip replacements have higher revision rates compared to conventional hip replacements in multiple registry studies. Minimizing impingement involves avoiding skirted heads, matching the femoral head with an appropriate acetabular implant and maximizing the head-to-neck ratio. Computer modeling studies indicate the optimal cup position is 45 to 55 degrees abduction. Angles less than 55 degrees require anti-version of 10 to 20 degrees of both the stem and cup to minimize risk for impingement and dislocation.