Patient-reported outcomes following patellofemoral and total knee replacement: an analysis of the 6–18 months postoperative period from the National Joint Registry
DOI:
https://doi.org/10.2340/17453674.2025.45115Keywords:
Arthroplasty, Knee, PatellofemoralAbstract
Background and purpose: Patellofemoral joint replacements (PFR) and total knee replacements (TKR) are surgical treatment options for patellofemoral joint osteoarthritis. We aimed to compare patient-reported outcome measures (PROMs) for these procedures, and revision thresholds for PFR.
Methods: Data from the National Joint Registry (2009–2021) was linked with the Hospital Episodes Statistics (HES) database. Data was then merged with the PROMs dataset and adjusted using inverse proportional treatment weighting methods. Primary PROMS were Oxford Knee Score (OKS) and EQ5D-3L at the 6–18-month mark with a minimal clinically important difference of 5 for OKS. Secondary outcome measures included threshold to revision, defined as the cut-off score at which an arthroplasty was revised. Differences in patient characteristics between those classed as best and worst outcomes were compared and regression analyses examined the influence of factors such as age, provider type (public or private healthcare), and comorbidities on PROMs with results stratified by sex.
Results: 340,449 matched records were analyzed (1,085 PFR, 339,364 TKR). The median postoperative OKS was 35 (PFR) and 38 (TKR), with a difference of –2.4. Patients with the best PFR outcomes were older (62.0 vs 57.2 years, P = 0.01). The median 6-month EQ5D-3L was 0.77 (PFR) and 0.80 (TKR). PFR had a higher revision hazard ratio (3.4, 95% confidence interval 2.7–4.4, P = 0.01), indicating a lower threshold for revision.
Conclusion: Up to 18 months, in terms of OKS and EQ5D-3L, there was no significant difference between the 2 procedures. PFR had a lower threshold for revision compared with TKR. Future research should incorporate more objective measures, such as activity level, where objective differences might be identified.
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Cardenas C, Wascher D C. Outcomes of isolated patellofemoral arthroplasty. J ISAKOS 2023; 9(4): 796-805. doi: 10.1016/j.jisako.2023.11.005. DOI: https://doi.org/10.1016/j.jisako.2023.11.005
Blazina M E, Fox J M, Del Pizzo W, Broukhim B, Ivey F M. Patellofemoral replacement. Clin Orthop Relat Res 1979; (144): 98–102. PMID: 535258. DOI: https://doi.org/10.1097/00003086-197910000-00017
Dahm D L, Al-Rayashi W, Dajani K, Shah J P, Levy B A, Stuart M J. Patellofemoral arthroplasty versus total knee arthroplasty in patients with isolated patellofemoral osteoarthritis. Am J Orthop (Belle Mead NJ) 2010; 39(10): 487-91. PMID: 21290009.
Vella-Baldacchino M, Webb J, Selvarajah B, Chatha S, Davies A, Cobb J P, et al. Should we recommend patellofemoral arthroplasties to patients? Bone Jt Open 2023; 4(12): 948-56. doi: 10.1302/2633-1462.412.BJO-2023-0100.R1. DOI: https://doi.org/10.1302/2633-1462.412.BJO-2023-0100.R1
Joseph M N, Achten J, Parsons N R, Costa M L. The PAT randomized clinical trial. Bone Joint J 2020; 102(3): 310-18. doi: 10.1302/0301-620x.102b3.bjj-2019-0723.r1. DOI: https://doi.org/10.1302/0301-620X.102B3.BJJ-2019-0723.R1
Odgaard A, Madsen F, Kristensen P W, Kappel A, Fabrin J. The Mark Coventry award: Patellofemoral arthroplasty results in better range of movement and early patient-reported outcomes than TKA. Clin Orthop Relat Res 2018; 476(1): 87-100. doi: 10.1007/s11999.0000000000000017. DOI: https://doi.org/10.1007/s11999.0000000000000017
Odumenya M, Costa M L, Parsons N, Achten J, Dhillon M, Krikler S J. The Avon patellofemoral joint replacement: five-year results from an independent centre. J Bone Joint Surg Br 2010; 92(1): 56–60. doi: 10.1302/0301-620x.92b1.23135. DOI: https://doi.org/10.1302/0301-620X.92B1.23135
Johnson Jr W B, Engh Jr C A, Parks N L, Hamilton W G, Ho P H, Fricka K B. A lower threshold for revision of aseptic unicompartmental vs total knee arthroplasty. Bone Joint J 2020; 102-B(6_Supple_A): 91-5. doi: 10.1302/0301-620x.102b6.bjj-2019-1538.r1. DOI: https://doi.org/10.1302/0301-620X.102B6.BJJ-2019-1538.R1
Lewis P L, Graves S E, Cuthbert A, Parker D, Myers P. What is the risk of repeat revision when patellofemoral replacement is revised to TKA? An analysis of 482 cases from a large national arthroplasty registry. Clin Orthop Relat Res 2019; 477(6): 1402-10. doi: 10.1097/CORR.0000000000000541. DOI: https://doi.org/10.1097/CORR.0000000000000541
Lonner J H, Jasko J G, Booth R E. Revision of a failed patellofemoral arthroplasty to a total knee arthroplasty. J Bone Joint Surg Am 2006; 88(11): 2337-42. doi: 10.2106/jbjs.f.00282. DOI: https://doi.org/10.2106/JBJS.F.00282
Liddle A D, Judge A, Pandit H, Murray D W. Adverse outcomes after total and unicompartmental knee replacement in 101 330 matched patients: a study of data from the National Joint Registry for England and Wales. Lancet 2014; 384(9952): 1437-45. doi: 10.1016/S0140-6736(14)60419-0. DOI: https://doi.org/10.1016/S0140-6736(14)60419-0
Boulton C, Harrison C, Wilton T, Armstrong R, Young E, Pegg D, et al. Implementing large-scale data quality validation in a national arthroplasty registry to improve compliance. Bone Jt Open 2022; 3(9): 716-25. doi: 10.1302/2633-1462.39.BJO-2022-0051.R1. DOI: https://doi.org/10.1302/2633-1462.39.BJO-2022-0051.R1
NHS England Digital. Patient reported outcome measures (PROMs). 2023. Available from: https://digital.nhs.uk/data-and-information/data-tools-and-services/data-services/patient-reported-outcome-measures-prom
Bottle A, Aylin P. Comorbidity scores for administrative data benefited from adaptation to local coding and diagnostic practices. J Clin Epidemiol 2011; 64(12): 1426-33. doi: 10.1016/j.jclinepi.2011.04.004. DOI: https://doi.org/10.1016/j.jclinepi.2011.04.004
Spece H, Kurtz M A, Piuzzi N S, Kurtz S M. Patient-reported outcome measures offer little additional value two years after arthroplasty. Bone Joint J 2025; 107-B(3): 296-307. doi: 10.1302/0301-620X.107B3.BJJ-2024-0910.R1. DOI: https://doi.org/10.1302/0301-620X.107B3.BJJ-2024-0910.R1
Austin P C, Stuart E A. Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies. Stat Med 2015; 34(28): 3661-79. doi: 10.1002/sim.6607. DOI: https://doi.org/10.1002/sim.6607
Beard D J, Harris K, Dawson J, Doll H, Murray D W, Carr A J, et al. Meaningful changes for the Oxford hip and knee scores after joint replacement surgery. J Clin Epidemiol 2015; 68(1): 73-9. doi: 10.1016/j.jclinepi.2014.08.009. DOI: https://doi.org/10.1016/j.jclinepi.2014.08.009
Scoring system for the Oxford knee score [cited 2022 Nov 2]. Available from: www.isis-innovation.com/...
Kalairajah Y, Azurza K, Hulme C, Molloy S, Drabu K J. Health outcome measures in the evaluation of total hip arthroplasties—a comparison between the Harris Hip Score and the Oxford Hip Score. J Arthroplasty 2005; 20(8): 1037-41. doi: 10.1016/j.arth.2005.04.017. DOI: https://doi.org/10.1016/j.arth.2005.04.017
Devlin N J, Parkin D, Browne J. Patient-reported outcome measures in the NHS: new methods for analysing and reporting EQ-5D data. Health Econ 2010; 19(8): 886-905. doi: 10.1002/hec.1608. DOI: https://doi.org/10.1002/hec.1608
Vella-Baldacchino M, Davies A, Bottle A, Cobb J, Liddle A. Association between surgeon volume and patient outcomes after elective patellofemoral joint replacement surgery using data from the National Joint Registry and Hospital Episode Statistics for England: population based cohort study. J Bone Joint Surg Am 2025; 107(8): 819-28. doi: 10.2106/jbjs.24.00703. DOI: https://doi.org/10.2106/JBJS.24.00703
Dickman P. Comparing Cox and flexible parametric models. Available from: https://www.pauldickman.com/software/stata/sex-differences-cox/.
Lambert P. STPM2: Stata module to estimate flexible parametric survival models, revised 18 Jan 2023. In: Statistical software components. Boston, MA: Boston College Department of Economics; 2010.
Lambert P, Royston P. Further development of flexible parametric models for survival analysis. Stata J 2009; 9(2): 265-90. doi: 10.1177/1536867X0900900206. DOI: https://doi.org/10.1177/1536867X0900900206
STATA. STATA 18. Your data tell a story. 2024. Available from: https://www.stata.com/.
Whitehouse S L, Blom A W, Taylor A H, Pattison G T R, Bannister G C. The Oxford Knee Score: problems and pitfalls. Knee 2005; 12(4): 287-91. doi: 10.1016/j.knee.2004.11.005. DOI: https://doi.org/10.1016/j.knee.2004.11.005
Scott C E H, Holland G, Keenan O J F, Ross L A, MacDonald D J, Lawson G M, et al. Radiographic severity, extent and pattern of cartilage loss are not associated with patient reported outcomes before or after total knee arthroplasty in end-stage knee osteoarthritis. Knee 2021; 31: 54-63. doi: 10.1016/j.knee.2021.04.003. DOI: https://doi.org/10.1016/j.knee.2021.04.003
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