Delta ceramic-on-alumina ceramic articulation in primary THA: prospective, randomized FDA-IDE study and retrieval analysis

Abstract

Wear and osteolysis continue to be major reasons for revision surgery in THA. Ceramic-on-ceramic bearings eliminate polyethylene wear debris. The newest generation of these bearings incorporate nanosized, yttria-stabilized tetragonal zirconia particles producing an alumina matrix composite. We asked whether this new material would perform as well as a conventional bearing in terms of functional hip scores, radiographic migration and osteolysis, complications and survival. As part of a US FDA investigational device exemption study (G000075), we conducted an initial prospective safety study of 21 alumina matrix composite femoral heads articulating on alumina liners followed by a prospective, randomized study with 44 more of these articulations and 45 zirconia femoral heads on polyethylene liners. The minimum followup for all patients was 26 months (mean, 73 months; range, 26-108 months). Harris hip scores and radiographic findings were similar in the two groups as was survivorship (trial 95% versus control 93%). There were three reoperations in the trial group and three in the control group. A fractured head retrieval showed a 33% monoclinic transformation with an increase in surface roughness from 3 to 5 nm at the main wear zone. While our numbers were insufficient to compare device-related complications, the trial device performed as well as the control device in terms of reoperation, and clinical and radiographic outcome. The alumina matrix composite femoral head on an alumina liner provided high survivorship.

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

Fig. 1

The study device consisted of a Biolox^® delta ceramic head (pink) articulated with a liner of Biolox^® forte ceramic (yellow) inset in polyethylene (white).

Fig. 2A–E

(A) A preoperative radiograph of a 40-year-old male patient shows osteoarthritis of the left hip. (B) A radiograph taken immediately postoperative to THA with a ceramic-on-ceramic articulation shows components in satisfactory position and alignment. (C) A radiograph at 70 months postoperatively reveals atraumatic fracture of the ceramic head and liner. (D) A radiograph taken immediately postoperative to revision THA confirms the use of a 32-mm-diameter cobalt-chrome femoral head with standard neck on crosslinked polyethylene liner with retained acetabular shell and femoral stem. (E) A radiograph at 14 months postoperative to revision of the head and liner demonstrates excellent fixation.

Fig. 3

Kaplan-Meier survivorship estimates with time with reoperation for any reason as the end point are shown. Tick marks represent censored patients. The dotted lines represent 95% confidence intervals. The survivorship was similar between groups at 90 months’ followup.

Fig. 4A–C

Overview of fracture fragments from a 28-mm delta ball from (A) polar view, (B) view of the base, and (C) side view of the stripe wear zone. The dominant fracture plane is indicated by dashed lines in the polar and basal views. The large stripe wear zone crosses over three of the fragments at the angle indicated by the dashed ellipse on the side view.

Fig. 5A–E

Photographs show five of the largest of seven fragments (A–E) from a fractured 28 mm ‘Delta’ ball. The circles indicate sites of analysis for polished main wear zone (MWZ), stripe wear zones (SWZ), metal contamination, machined taper bore and fracture cleavage regions (CZ).