Topic Ceramic on Ceramic

Executive Summary

3rd generation alumina-on-alumina in modular hip prosthesis: 13 to 18 years follow-up results

Authors
A. Toni, F. Giardina, G. Guerra, A. Sudanese, M. Montalti, S. Stea, B. Bordini
Rizzoli Orthopaedic Institute, Bologna, Italy
Journal
Hip Int 2017 Feb 21;27(1): 8-13. doi: 10.5301/hipint.5000429. EPub 5002016.
Level of Evidence
Level IV (Case series)

Summary

Toni et al. analysed 248 cementless THAs with 28 mm CoC bearings (BIOLOX®forte) in 235 patients with a mean age of 55.5 years at time of surgery. All stems were Ti-alloy with a modular titanium alloy neck. Primary diagnosis was mostly primary osteoarthritis (57.3 %) followed by osteoarthritis due to developmental dysplasia (23.8 %), and others. Mean follow-up was 16.5 years, ranging from 14-19 years. The Merle-D’Aubigne and Postel hip score was used for clinical assessment. At final follow up it had improved significantly from 11.4 to 17.4. Overall survivorship after 15 years with revision as endpoint was 93.2 %; considering prostheses failure as endpoint it was 97.2 %. Early complications such as pulmonary embolism was found in one patient and early posterior dislocation in three hips, which were treated by closed reduction without recurrence.

Only one acetabular component was not stable and revised. On the femoral side 10 stems were initially rated fibrous stable, only one of which had to be revised later due to loosening. Periprosthetic partial radiolucent lines were found in 17 cases but remained asymptomatic. There were 4 cases (1.6 %) of squeaking (2 intermittent) and 3 cases of ceramic liner fracture after about 5 years. Two of the squeaking cases were linked to ceramic liner fracture. In the 3 patients with a fractured ceramic liner posterior neck-to-cup impingements was identified as a reason during revision and implant position was changed during the intervention. The authors conclude that the use of 3rd generation CoC bearings in cementless THA, in their hands, provided excellent long-term results comparable to the results of the clinical literature with CoC bearings if the implant components are positioned correctly and functionally stable. However, although squeaking does not seem to be a problem for the patient, it may be a sign for impending ceramic fracture mid to long-term, if the position of the components leads to neck-liner impingement.

Study Limitations

Key Messages

Commentary

This is another long-term, single-center retrospective observational cohort study with 3rd generation CoC bearings THA. The reported survivorship in this case series was similar to other recent CoC publications, despite using modular necks and 28 mm bearings. An issue with the 28 mm head CoC bearing in this publication seems to be the appropriate positioning of the implant with neck-liner impingement and consequently liner fracture. Nevertheless, experience of other authors with CoC does not confirm that noise is a predictor of pending ceramic failure, but is rather the consequence of a fracture.

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