Highest Risk Period for Early Revision of Total Hip and Knee Replacement Differs

Patients need to know the benefits, risks and alternatives to any proposed treatment. Surgeons discussing the risk of a revision procedure becoming necessary, after a hip or knee replacement can draw upon the orthopaedic literature and arthroplasty registries for long-term implant survival. However, early revision is required in a minority of cases. We have investigated whether the probability of revision is similar for hip and knee replacement patients in terms of time-point and indication for revision.

Of the 22,046 Primary Total Hip Replacements (THR) and Primary Knee replacements (TKR), undertaken by 23 surgeons, between January 2004 and March 2015, 1.35% (297) were subsequently reported to the National Joint Registry (NJR) as revised. Each revision case was reviewed. The modes of failure of were identified through clinical, laboratory and imaging (x-rays, CT, MRI and Isotope scans) studies.

Of the 9,411 primary THRs, 160 (1.60%) were reported as revised. The revision rate was 0.58% in the first year. This was statistically higher than all subsequent years. There was no statistical difference between any pair of subsequent years with an average of 0.3% per annum. The odds ratio for revision during the first post-operative year against the subsequent year average was 1.67.

Of the 12,635 primary TKRs, 137 (1.08%) were reported as revised. The highest revision rate occurred during the second year (0.42%). This was statistically higher than any other year. However, the revision rate in both the first and third years (0.29% and 0.26% respectively) were also statistically higher than in the subsequent years. Thereafter, the average revision rate was 0.11% with no statistical difference between the years.

The main indications for first year hip revisions were infection, dislocation and peri-prosthetic fracture. The indications for the early knee revisions were aseptic tibial component loosening, infection and progressive patella-femoral disease.