Methods and Results

Using data extracted from the NJR a series of 128 PFJ revisions in whom the index primary procedure was also recorded in the NJR were identified. This cohort therefore represents early failures of PFJ replacements revised over a 2 year period which were implanted after April 2003 and included revisions of 11 different brands of PFJ replacement from 6 different manufacturers.

The median age at primary procedure was 59.0 (Range 21.1 to 83.2) of which 43 patients were <55 years old (31 males, 97 females). 19% of the revisions were performed in the first year after implantation, in the second year in 33 cases (26%), in the third year in 39 cases (31%) and between years 4 to 7 in 32 patients (25%).

The commonest reasons for revision were pain (35%), aseptic loosening (18%), subluxation, dislocation or instability (11%), PE wear (7%) and component malalignment (6%). No reason for revision was stated in 30% and only 2 cases were revised for infection. Reason for revision differed according to year of failure but was consistent with respect to age at primary surgery. PFJ revision reason differed from those stated for revisions of primary UKR and TKR from the same period with pain being more prevalent and aseptic loosening and infection being less prevalent in the PFJ group. Single stage revision was performed in 124 cases and 118 underwent cemented revision.