Summary
There are no clinical differences in terms of 6-month OKS and EQ5D-3L between the two procedures. At the same patient reported outcome score, PFR patients were more likely to be revised than TKR patients
Abstract
Introduction
Patellofemoral joint replacements and total knee replacements are viable surgical treatment options for patellofemoral joint osteoarthritis. The aim of this study was to determine differences between both procedures in terms of the Oxford Knee Score (OKS), subsets of the OKS focusing on the patellofemoral joint function, and thresholds to revision using the OKS and EQ5D-3L.
Methods
Patellofemoral arthroplasty (PFR) and primary total knee arthroplasty (TKR) records in the national joint registry from 2003 to December 2021 were linked to the hospital episodes statistics (HES). Primary outcome measures were Oxford Knee Score and EQ5D-3L at the 6-month mark. Secondary outcome measures included threshold to revision, defined as the OKS cut-off at which an arthroplasty was revised. Dand differences in patient characteristics between those classed as best and worst outcomes were compared. A mixed effects multilevel logistic model was performed to examine the relationship of the four questions in the OKS thought to represent patellofemoral joint function in order to assess differences between PFRs and TKRs.
Results
There were a total of 286,216 matched records for analysis with 787 PFR and 266,185 TKR. The mean 6-month post-operative OKS for PFR was 33 (SD 11), whilst for TKR, the mean 6-month post-operative OKS was 36 (SD 9.5), with a difference of –3.68. Patients who had a PFR operation and achieved the best scores were more likely to be older compared with those who achieved the worse scores, 62 (60.28 - 63.6) compared with 58 (56.95-59.84) p=0.01 respectively. For each patellofemoral joint question in the OKS, TKR scored higher compared with PFR. The mean 6-month post-operative EQ5D-3L for PFR was 0.75 (SD 0.19), while the mean 6-month post-operative EQ5D-3L for TKR was 0.79 (SD 0.15). PFR operations were more likely to be revised at a lower Oxford Knee Score compared with TKR and therefore have a higher hazard ratio 3.36 (95% CI 2.55–4.43, 0.01).
Conclusion
In terms of 6-month OKS and EQ5D-3L, there was no difference between the two procedures. In the age of active ageing, future research should use more objective measures such as volume of activity rather than simply the ability to perform everyday activities before completely eliminating the PFR surgery procedure