Retrospective cohort study of the performance of the Pinnacle metal on metal (MoM) total hip replacement: a single-centre investigation in combination with the findings of a national retrieval centre.

Objectives: To determine risk factors for revision in patients implanted with a commonly used metal on metal (MoM) hip replacement.

Design: Retrospective cohort study in combination with a prospective national retrieval study (Northern Retrieval Registry (NRR)).

Setting: Combined orthopaedic unit in combination with the NRR.