Abstract
IntroductionPatellofemoral joint osteoarthritis (OA) is common and leads to pain and disability. However, current classification criteria do not distinguish between patellofemoral and tibiofemoral joint OA. The objective of this study was to provide empirical evidence of the clinical features of patellofemoral joint OA (PFJOA) and to explore the potential for making a confident clinical diagnosis in the community setting.MethodsThis was a population-based cross-sectional study of 745 adults aged ≥50 years with knee pain. Information on risk factors and clinical signs and symptoms was gathered by a self-complete questionnaire, and standardised clinical interview and examination. Three radiographic views of the knee were obtained (weight-bearing semi-flexed posteroanterior, supine skyline and lateral) and individuals were classified into four subsets (no radiographic OA, isolated PFJOA, isolated tibiofemoral joint OA, combined patellofemoral/tibiofemoral joint OA) according to two different cut-offs: 'any OA' and 'moderate to severe OA'. A series of binary logistic and multinomial regression functions were performed to compare the clinical features of each subset and their ability in combination to discriminate PFJOA from other subsets.ResultsDistinctive clinical features of moderate to severe isolated PFJOA included a history of dramatic swelling, valgus deformity, markedly reduced quadriceps strength, and pain on patellofemoral joint compression. Mild isolated PFJOA was barely distinguished from no radiographic OA (AUC 0.71, 95% CI 0.66, 0.76) with only difficulty descending stairs and coarse crepitus marginally informative over age, sex and body mass index. Other cardinal signs of knee OA - the presence of effusion, bony enlargement, reduced flexion range of movement, mediolateral instability and varus deformity - were indicators of tibiofemoral joint OA.ConclusionsEarly isolated PFJOA is clinically manifest in symptoms and self-reported functional limitation but has fewer clear clinical signs. More advanced disease is indicated by a small number of simple-to-assess signs and the relative absence of classic signs of knee OA, which are predominantly manifestations of tibiofemoral joint OA. Confident diagnosis of even more advanced PFJOA may be limited in the community setting.
Highlights
Patellofemoral joint osteoarthritis (OA) is common and leads to pain and disability
Comparative clinical features: ‘any OA’ When applying the lower threshold definition of radiographic OA, the numbers of participants classed as no radiographic OA, isolated patellofemoral joint OA, isolated tibiofemoral OA, and combined patellofemoral/ tibiofemoral joint OA were 236 (32%), 178 (24%), 30 (4%) and 301 (40%), respectively
Due to the small number with isolated tibiofemoral joint OA, modelling was limited to comparing the clinical features of no radiographic OA, isolated patellofemoral joint OA and combined patellofemoral/tibiofemoral joint OA
Summary
Current classification criteria do not distinguish between patellofemoral and tibiofemoral joint OA. In a total population of 57,555 adults registered with UK general practices, only 13 cases had a recorded diagnosis by the general practitioner of patellofemoral joint OA; less than 1% of knee consulters in a year [3]. There is growing evidence indicating that patellofemoral joint OA impacts independently on symptoms and function [4,5,6,7,8,9], that it frequently occurs in the absence of tibiofemoral disease [4,6,10,11,12,13], and that its aetiology and, risk profile and management, may differ [12,14,15,16,17]. In the context of recommendations that OA can often be confidently diagnosed without the need for imaging [2,25], these developments pose a fundamental question: can patellofemoral joint OA be identified in routine clinical practice and, if so, which features are most informative?
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
