Findings: The quadriceps tendon demonstrates severe pathological changes throughout its entire length from the myotendinous junction to patellar insertion. Marked diffuse thickening measures 11.5mm in the central portion, representing more than 70% increase from normal values. The normal homogeneous parallel fibrillar echostructure is completely obliterated, replaced by a severely heterogeneous appearance with no recognizable organized tissue pattern. Extensive areas of mucoid degeneration appear as large confluent hypoechoic zones (largest measuring 15x8mm) occupying approximately 40% of the cross-sectional area, indicating advanced tendon necrosis. Multiple large intratendinous calcifications are present throughout the tendon substance: at least 8-10 distinct calcific deposits ranging from 3mm to 12mm in diameter, with the largest forming a continuous calcified plaque in the distal third. These calcifications demonstrate dense hyperechoic appearance with prominent posterior acoustic shadowing. Severe enthesopathy is evident at the patellar insertion with marked irregularity of the patellar base, multiple erosions (largest 8x5mm), and extensive reactive bone formation creating irregular osteophytic spurs. The superior pole of the patella shows severe cortical disruption with loss of normal bone architecture. Evidence of partial-thickness tear is present in the superficial fibers of the mid-substance, with a hypoechoic cleft extending 8mm in length and 4mm in depth, representing approximately 35% cross-sectional involvement. The deep fibers show severe disorganization but maintain some continuity. The myotendinous junction demonstrates abnormal thickening and irregularity with extension of pathological changes into the distal muscle belly. Extensive intratendinous fibrosis is evident as hyperechoic bands and nodules interspersed with the degenerative areas. Color and Power Doppler reveal marked pathological neovascularization with chaotic vascular pattern throughout the tendon, particularly concentrated around the areas of mucoid degeneration and at the enthesis. Multiple large feeding vessels (>1mm diameter) penetrate the tendon from both anterior and posterior surfaces, indicating active chronic inflammatory process. Peritendinous changes include marked thickening of the paratenon (4mm) with loss of normal gliding planes and extensive adhesions to surrounding tissues, particularly to the suprapatellar fat and prefemoral fat pad. Dynamic examination during attempted knee extension demonstrates severely impaired tendon excursion with rigid, non-elastic behavior and lack of normal lengthening-shortening pattern. The tendon appears functionally compromised with evidence of mechanical insufficiency contributing to the extensor lag observed clinically. Measurement of the anterior-posterior thickness shows asymmetric thickening with the anterior portion measuring 13mm and posterior portion 9mm, indicating heterogeneous degenerative process. Multiple focal areas of tendon discontinuity suggest previous partial rupture episodes with attempted healing through disorganized scar tissue formation.