Abstract
Total Hip Replacement has become the most successful operation in the latter half of the 20th century for relief of pain and restoring function of the arthritic hip. Many improvements in surgical technique and implant technology have enhanced recovery, reduced complications, and increased implant survivorship. Minimising the complications of impingement, dislocation, bearing-wear, and implant loosening remain goals for surgeons and implant design.
Patients at higher risk for post-operative dislocation including patients with high pre-op hip ROM, femoral neck fracture, posterior surgical approaches, smaller femoral head sizes, and most importantly folks undergoing revision THA may influence dislocation as much as component position. A tripolar type of articulation, where there is an additional bearing with a mobile polyethylene component between the prosthetic head and the acetabular shell, increase functional head diameter, reduce neck – component impingement, and reduce dislocation. These implants may greatly assist in the treatment of recurrent dislocation of the hip and in reducing the high rate of dislocation that follows revision THR as proven by many French authors connecting the world to this innovative technology.
Aseptic loosening of monolithic cups (through inadequate initial fixation) and inner smaller femoral head dislocation from the larger polyethylene head remain risks with dual mobility deign that require longer-term follow-up of newer designs before we declare victory in this space. It appears in patients at high risk for dislocation that a dual mobility type articulation may be worth the potential trade off of increased volumetric wear, intra-prosthetic dislocations, and acetabular loosening. Without additional outcomes data in this space wide spread use should be cautious.
