Abstract

Background: Knee osteoarthritis (KOA) pain is often misattributed to cartilage structural degeneration. Yet cartilage is aneural, avascular, and alymphatic-incapable of generating pain. Doppler ultrasound enables biologic phenotyping, distinguishing synovitis, iliotibial band syndrome (ITBS), and subchondral insufficiency fracture (SCIF). “KOA is not a picture-it’s a phenotype.” 1 Objective: To classify KOA pain into Wet, Dry, and Equivocal phenotypes using Doppler ultrasound and guide targeted interventions based on biologic activity rather than structural findings.2,3 Methods: Over a decade of Doppler-guided assessments in a single-surgeon orthopedic clinic, patients were phenotyped based on vascular signal and fascial strain. Interventions were tailored to biologic activity.4 Results:Wet KOA shows Doppler-positive synovitis and responds to anti-inflammatory strategies. SCIF presents as acute pain with marrow edema and cytokine activation. Emerging biologics (IL-6, TNF-α, GM-CSF inhibitors) and Arthrosamid® hydrogel support the logic of targeting synovitis directly. Even if unavailable locally, they validate the Doppler framework.5–7 Dry KOA, dominated by ITBS and GTPS, mimics sciatica and is frequently misdiagnosed. MRI often misses fascial strain and early synovitis, leading to unnecessary spinal interventions.8–10 “Dry knees hurt-but not from the joint.” New Insight: Dry KOA phenotypes frequently present with coexisting ITBS and GTPS, both arising from strain along the iliotibial band and its fascial continuum. GTPS, once considered bursitis, is now recognized as gluteal tendinopathy-primarily involving the gluteus medius and minimus, compressed by ITB tension. (Radiopaedia.org, 2025; European Spine Journal, 2018) “GTPS and ITBS are not neighbors-they’re twins.” These overlapping conditions are often misdiagnosed as sciatica, leading to ineffective treatments and unnecessary imaging. Doppler ultrasound and clinical palpation redirect therapy toward fascial strain and localized intervention. (TRACE Body Rejuvenation, 2024; Orthobullets, 2025) “Pain in the outer thigh isn’t always spinal-it’s often trochanteric. sterolateral pain is not a nerve-it’s a fascia.” Conclusion: KOA pain is a biologic signal-not a structural artifact. Doppler-guided phenotyping enables pragmatic, low-cost, targeted treatment. MRI findings must be reframed as contributors-not causes. “MRI sees everything-except the pain.” We don’t chase shadows-we treat the signal.” “KOA is not a picture-it’s a phenotype.” 

Keywords

doppler, osteoarthritis