Impact of the patellofemoral and tibiofemoral phenotype on 10-year symptomatic and radiographic progression of knee osteoarthritis in the check study

Abstract

Purpose: Most research in osteoarthritis (OA) is still focussed on the tibiofemoral (TF)-joint, though patellofemoral (PF) OA appears more prevalent and is a significant source of pain and associated disability. Therefore, this study addresses the following aims: 1. Describe differences in patient characteristics between patients with PFOA and TFOA; 2. Describe the clinical trajectory of patients with PFOA and TFOA during 10-year follow-up and 3. Identify risk factors for the progression of structural PFOA and TFOA. Methods: For this study data of the Cohort Hip and Cohort Knee study (CHECK) were used. Patients with early OA symptoms of the knee were selected. All patients completed a questionnaire and underwent physical examination at baseline and after 2, 5, 8 and 10 years follow-up. The questionnaires informed on demographics and symptoms (e.g., WOMAC, pain (NRS)); the physical examination included range of motion and provocation tests (e.g., grinding test, joint line tenderness) and at baseline, T2, T5 and T8 three radiographs of the knee were obtained (anterior–posterior, lateral and skyline. Severity of radiographic PFOA and TFOA was defined using the Kellgren & Lawrence score. Structural progression of PFOA and TFOA was defined as a shift from normal/mild at baseline to moderate/severe OA during 8-year follow-up. Risk factors for radiographic progression of both PFOA and TFOA were analysed using multivariate logistic regression models. The impact of PFOA and TFOA progression on the change in WOMAC score during 10-year follow-up were analysed using linear regression models, with adjustment for age, gender and BMI. Results: The total cohort included 847 participants with knee complaints (mean age 55.9 (SD 5.2), 80% female, 26.3 kg/m2 BMI). At baseline, 10.7% (N = 91) had isolated PFOA, 5.7% had isolated TFOA (N = 48) and 9% (N = 76) had OA in both joints (COA) (Fig. 1). Participants with isolated PFOA had significantly less bilateral complaints and less knee flexion range of motion at baseline compared to participants with isolated TFOA. No significant association was found between the presence of PFOA and TFOA at baseline and experienced pain and function at the different follow-up points (Fig. 2). Of the subjects with PFOA at baseline, 30 subjects (33.0%) had structural PFOA progression during follow-up and 65.9% had structural TFOA progression. Of the participants with isolated TFOA at baseline, 8.3% showed TFOA progression and 27.1% showed PFOA progression. Of the total study population, 37.8% (n = 320) showed radiographic progression of PFOA while 30.9% (n = 262) showed progression of TFOA. Total knee prosthesis (TKP) during follow-up were performed in 14.3% of the subjects with PFOA baseline compared to 2.1% of the subjects with TFOA at baseline. Of all subjects with radiographic PFOA progression, 5.3% received a TKP during follow-up compared to 10.7% of the subjects with TFOA progression. Radiographic progression of PFOA (B −0.98; 95% CI −4.39; 1.48) and TFOA (B −0.07, 95% CI −5.41; 0.30) were not associated with a change on the WOMAC score. The only risk factor found for radiographic progression of PFOA was a positive patellofemoral grinding test (OR 1.55, 95% CI 1.03; 2.35). Risk factors for the progression of TFOA included a KL-score ≥2 (OR 6.57, 95% CI 3.45; 12.51) and absence of Heberden Nodes (OR 0.58, 95% CI 0.39; 0.87). Conclusions: No differences seem to exist in the clinical trajectory of patients with PFOA or TFOA, neither does the radiographic progression impact the clinical trajectory during 10-year follow-up. Though, patients with PFOA at baseline are likely to progress in both the PFOA and TFOA joint, and received more TKPs. Finally, patellofemoral grinding is shown to be a risk factor for PFOA progression, but not for TFOA progression.View Large Image Figure ViewerDownload Hi-res image Download (PPT)