Quantitative assessment of patellofemoral osteoarthritis via the pressure band test: an innovative and objective test.

Background: Patellofemoral osteoarthritis (PFOA) is a prevalent subtype of knee osteoarthritis (OA), but due to its nonspecific symptoms and costliness in imaging, it is difficult to diagnose accurately, with the currently available methods lacking sensitivity and accessibility. This study aimed to develop and validate a novel, noninvasive, and cost-effective pressure band test (PBT) for the quantitative assessment of PFOA severity. Methods: This prospective cross-sectional study consecutively enrolled 1,059 participants between September 2022 and March 2024. Pain thresholds, defined as the lowest pressures needed to induce pain, were measured via a standardized PBT and validated against magnetic resonance imaging (MRI)-based Outerbridge scores, Kellgren and Lawrence (K&L) grading, and various patient-reported outcome measures (PROMs), including the numeric rating scale (NRS) for pain and the Lysholm Knee Scoring Scale. Statistical analyses included Pearson and Spearman correlation coefficients, receiver operating characteristic (ROC) curves, logistic regression models, calibration curves, decision curve analysis (DCA), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Nomograms were developed to facilitate individualized risk assessments, while subgroup and sensitivity analyses were applied to examine variations in NRS scores and other measurements. Results: ROC analyses demonstrated that models incorporating pressure measurements significantly outperformed those without them, achieving area under the curve values of 0.815 for the patella and 0.817 for the femur. Logistic regression confirmed that higher pressures correlated with a lower likelihood of PFOA. Notably, PBT's performance remained consistent across different NRS subgroups. Conclusions: PBT demonstrated significant potential as a valuable tool for the quantitative assessment of PFOA severity. This noninvasive and costeffective method may enhance diagnostic precision and be productively incorporated into routine clinical assessments. However, further research is necessary to validate these findings, clarify the long-term benefits, and evaluate the limitations of PBT in a diversity of clinical settings.