Salvage of failed acetabular cages by nonbuttressed trabecular metal cups

Abstract

Acetabular revision of failed cages or rings may be facilitated by previously placed bone graft, enabling the use of highly porous cementless hemispheric cups. We retrospectively reviewed all 15 patients who had conversion of failed antiprotrusion cages (10 patients) or roof rings (five patients) to cementless cups. All patients had restoration of bone stock (three major column, eight morselized, four combined bone grafts) performed in conjunction with their index cage or ring reconstruction arthroplasty. The minimum followup was 24 months (average, 48.3 months; range, 24-72 months). Failure was defined as radiographic cup migration. In 12 of the 15 patients, there was no radiographic change in cup position at the last followup or symptoms indicative of loosening. The average Harris hip scores improved from 31 (range, 15-48) to 69 (range, 56-87) at latest followup. Cup failure occurred in three patients. In two patients, the failed cups were revised; the third patient refused additional surgery. Our experience suggests treatment of failed cages by highly porous cementless cups is a reasonable option. However, we recommend patients be followed closely to detect cup migration, which can occur until satisfactory bony ingrowth occurs.

Level of evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Fig. 1

A 76-year-old patient presented with a failed antiprotrusion cage. Note the broken hardware and a distorted ischium.

Fig. 2

Postoperative radiographs of the patient at 6 weeks postconversion from a failed antiprotrusion cage to trabecular metal cup. Note that the broken screws did not require removal and were left in situ.

Fig. 3

Postoperative radiographs of the patient at 2 years postconversion from failed cage to trabecular metal cup. There is no change in cup position or presence of radiolucent lines.