Acetabular revision using a press-fit dual mobility cup.

INTRODUCTION: Dual mobility cups are especially indicated in total hip replacement revision, the risk of recurrent instability being greater than in primary surgery. In revision, however, primary cup fixation is uncertain without routine anchoring screws.

HYPOTHESIS: The stability of dual mobility cups impacted without cement, supplementary screw(s) or anchoring pegs fixation is satisfactory in total hip arthroplasty acetabular component revision, and prevents instability accidents.

PATIENTS AND METHODS: Twenty three patients were operated on by the same surgeon between January 1999 and December 2006 and prospectively followed up to a mean 4 1/2 years (range,2-10 yrs). A Collégia cup (Wright Medical France, Créteil, France) was impacted in 23 total hip arthroplasty acetabular component revisions, including 17 cases of SOFCOT grade-1 bone-stock loss and six of grade 2.

RESULTS: There were six clinically poor results on the Merle D'Aubigné scale. One case of early migration occurred, in a multioperated acetabulum. There was one isolated dislocation and one recurrent dislocation associated with loose greater trochanter nonunion, but tolerated as it was infrequent.

DISCUSSION: This option simplifies revision surgery and limits the risk of dislocation if the abductor muscles unit is continuous. It is indicated when local bone-site compromise encompass a wall-contained cavitary defect at most. A medial wall defect, if moderate, does not in our view preclude using a primary cup, impacted with a certain degree of protrusion. Longer-term follow-up will be needed to confirm these medium-term findings.

LEVEL OF EVIDENCE: Level IV. Prospective non comparative therapeutic study.