Detaillierte Beitrags-Information
| Beitragstitel | It’s worth cleaning – The sole examination of the female taper identified the cause of a trunnion failure 16 years after total hip arthroplasty |
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| Beitragscode | P041 |
| Autoren | |
| Präsentationsform | Poster |
| Themengebiete |
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| Abstract |
Introduction: Adverse reaction to metal debris (ARMD) is a well-known issue of total hip replacements (THR) with metal-on-metal (MoM) pairings. This however mainly affects large-head MoM THR, whereas small diameter (28-32 mm) MoM pairings are associated with low long-term revision rates. The pairing however does not necessarily cause failure. This report documents a failure due to trunnionosis of a correctly oriented small-diameter MoM THR. Identification of the cause was possible through sole analysis of the female taper, as the stem had not been revised. This technique is routinely not available. But this case illustrates the importance of cleaning the taper when seating the head in THR. Methods: Case presentation, complemented with results from advanced analysis of the retrievals. A 65 year old male patient had been revised 16 years after THR with 28 mm MoM pairing, due to local ARMD. As both the cup and the stem were well integrated and oriented, and considering body weight of 120 kg, revision solely of the inlay and the head was performed, through an anterior approach. A semi-fluid necrotic tumor of ~1000 ml was evacuated. Despite distinct wear of the male taper, the stem was left in place and reconstruction performed with a head with inner skirt. The follow-up of actually 2 years was unproblematic. While the cup and the outer surface of the head were accessible to direct analysis by a coordinate measuring machine, the female taper had to be analyzed indirectly by measuring an imprint. Results: Histology showed acellular necrosis, as typically associated with metal wear particles. Wear on the surface of the cup and of the head was within expected ranges. The analysis of the female taper identified 2 particles within the taper connection, which can reasonably only be bone fragments, that probably caused failure. The defect on the softer male taper titanium alloy was more important than the one identifiable on the firmer CoCr counterpart. Conclusion: Failure due to ARMD after MoM THR is not necessarily caused by the pairing, but can be due to trunnionosis. When the stem is not retrieved, analysis of the taper requires indirect measurements using an imprint of the female taper, a technique commonly not available. Observations made in this case underscore the importance of optimal technique, especially cleaning, when seating the head on the taper when performing THR to avoid failures due to trunnionosis. |