The Impact of the Largest National Joint Registry on Current Knee Replacement Longevity Estimates: An Analysis and Review of Knee Prosthesis Brand and Fixation Technique.

BACKGROUND

The UK National Joint Registry is the single largest joint registry in the world enrolling 1.3 million patients and recently reaching 17 years of follow-up data. Current knee prosthesis longevity estimates are based off smaller sized international registries and the impact of fixation type on prosthesis survival remains unclear.

METHODS

We used the UK National Joint Registry 17th annual report to calculate pooled mean survival estimates of total knee replacements (TKRs), unicondylar knee replacements (UKRs), and patellofemoral knee replacements at 10 and 15 years based on both construct brand and fixation technique (cemented vs uncemented). Independent t-testing was performed for significance.

RESULTS

All-cause survivorship of TKRs at 10 and 15 years is 96.7% and 95.4%, respectively. For UKRs it is 89.8% and 80.7% and for patellofemoral knee replacements it is 81.6% and 76.5%. In regard to fixation technique, cemented and uncemented TKRs show similar survivorship at both time points. For UKRs uncemented constructs showed improved survivorship compared to cemented at 10 years (92.7% vs 88.2%, P < .001). This was greatest among those <65 years of age. In fact, all construct types regardless of fixation showed increased rate of revision in those <65 years vs those ≥65 years.

CONCLUSION

We provide more accurate estimations for knee prosthesis survival and highlight that younger patients, particularly those receiving UKRs, are prone to greater revision risks. This data also suggests that uncemented fixation may offer improved joint survival in these patients.