High hip center in revision arthroplasty.

What is the effect of superior placement of the acetabulum in complex hip reconstruction? Twenty-two patients (23 cases) had revision hip arthroplasty with superiorly placed porous-coated components without bone-grafts. Cemented femoral components were used in 21 cases and ingrowth components in 2. The average vertical height (corrected for magnification) was 36.8 mm from the interteardrop line, compared to a contralateral normal height of 12.1 mm. Three patients were deceased. The remaining 19 patients (20 hips) had a minimum 2-year follow-up period (average, 35 months). Fourteen hips had two or more previous surgeries. Seven acetabular components had thin (< 1 mm), nonprogressive, incomplete radiolucent lines. One acetabulum had a complete 1 mm radiolucent line in an asymptomatic patient. The remaining 12 acetabular components had no evidence of radiolucent lines and none of the acetabular components migrated. One hip with a cemented femoral component had evidence of possible loosening. Two cemented femoral components had evidence of definite loosening, one with minimal clinical symptoms and the other was revised to a long stem at 14 months after revision. Of the two ingrown femoral components, one had initial subsidence of 1.5 cm and both had thigh pain. All other patients had improved from their preoperative status; however, 4 of 20 hips had moderate to severe pain. Superior cup position did not result in concomitant lateral position. With a short-term follow-up period however, vertical displacement alone resulted in high loosening rates, with 25% for the femur and 5% for the acetabulum.