HISTORY: 69 y/o Caucasian Male who runs for fitness, presented to Sports Medicine Clinic with 2 days of severe R Knee pain, swelling, limping and inability to extend his leg. No significant PMH. Reported no trauma or change in running habits. No previous corticosteroid injection. Recalled recently lifting a heavy sofa and going up and down stairs while cleaning his attic over the past weekend. No bruising or distal numbness, weakness or tingling. Minimal relief with Acetaminophen and Ice. PHYSICAL EXAMINATION: Examination revealed suprapatellar edema, tender over quadriceps tendon above patella. Unable to squat. Full active extension. Strength 5/5 on resisted straight leg raise. No ecchymosis. Remainder of knee exam unremarkable. DIFFERENTIAL DIAGNOSIS: Osteochondritis Dissecans of Patella, Patellar Dislocation, Patellar Fracture, Patellar Tendon Rupture, Patello-Femoral Syndrome, Pre-Patellar Bursitis, Quadriceps Contusion, Quadriceps Strain, Quadriceps Tendinitis/Tendinosis. TEST AND RESULTS: 4 Radiographic Views of the Knee. Lateral View: oblique fractured calcification within the substance of the Quadriceps tendon. FINAL WORKING DIAGNOSIS: Fracture of Calcific Tendinosis within Quadriceps Tendon TREATMENT AND OUTCOMES: Immobilization with Post-Op Knee Brace in 5 degrees of Flexion. Ice. NSAID. Gentle range of motion exercises. Advance range of motion gradually. Progress to Physical Therapy for Quadriceps flexibility/strengthening with emphasis on eccentric contraction. Repeat Films at 3 and 6 weeks.