Abstract
The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A pre-operative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to the ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. Eighty-eight percent were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. Eighty-one percent had a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the pre-operative time required to manufacture the device – typically 4–8 weeks.
