Frequency of Patellofemoral Arthritis among Fibromyalgia Patients with Chondromalacia Patella: A Clinical and Radiological Study

Background: Fibromyalgia (FM) is frequently associated with musculoskeletal (MSK) comorbidities, however, the extent to which chondromalacia patella (CMP) is associated with patellofemoral arthritis (PFA) in FM patients has not been well established. Objective: This study aimed to assess the frequency of PFA among patients with FM diagnosed with CMP using both clinical and radiological assessments. Patients and Methods: This cross-sectional study enrolled 90 patients with FM, diagnosed according to the 2016 revised ACR classification criteria. Clinical assessments, functional scores, and knee MRI were performed, with CMP and PFA graded on MRI and Sperner classification, respectively. Results: patients with FM with late-stage CMP demonstrated significant impairments across all the functional knee injury and Osteoarthritis Outcome Score (KOOS) domains (p<0.001). Clinical assessment revealed that this group also had significantly lower Kujala scores (p<0.001), elevated Q angles (p<0.001), and higher tender point (p<0.001) and wide spread index (WPI) values (p=0.004) compared with early-stage CMP and controls. Advanced grades of PFA, particularly Grades 2 and 3, were predominantly observed in late-stage CMP (p<0.05) and were strongly correlated with both functional and clinical parameters. Radiological parameters have limited value in detecting PFA regarding the different indices of the PF articulation. Multivariate regression analysis confirmed that pain severity (p=0.028), low Kujala scores (p=0.007), greater Q angle (p<0.001), and higher tender point burden (p=0.002) were independent predictors of a higher PFA grade. Conclusion: Patients with FM with late-stage CMP show a significantly higher frequency and severity of PFA, as demonstrated by clinical impairment, altered biomechanics, and MRI evidence of structural degeneration. A multimodal approach that integrates clinical, functional and radiological assessments is essential for early PFA detection and management in this vulnerable population. ？