Summary Patellar tendinitis is tendinopathy of the patellar tendon associated with activity-related anterior knee pain. Diagnosis is primarily made clinically with tenderness to palpation at the distal pole of patella in full extension. Treatment is generally nonoperative with resting, ice, activity modifications and physical therapy to focus on hamstring, quadriceps and core strengthening. Epidemiology Incidence up to 20% of jumping athletes Demographics males > females Risk factors volleyball most common more common in adolescents/young adults quadriceps tendinopathy is more common in older adults poor quadriceps and hamstring flexibility Etiology Pathophysiology mechanism repetitive, forceful, eccentric contraction of the extensor mechanism histology degenerative, rather than inflammatory micro-tears of the tendinous tissue are commonly seen Classification Blazina classification system Blazina classification system Phase I Pain after activity only Phase II Pain during and after activity Phase III Persistent pain with or without activities (deterioration of performance) Presentation Symptoms insidious onset of anterior knee pain at inferior border of patella initial phase login to view 1 more bullet late phase login to view 2 more bullets Physical exam inspection may have swelling over tendon palpation tenderness at inferior border of patella provocative tests Basset's sign login to view 2 more bullets Imaging Radiographs recommended views AP, lateral, skyline views of knee findings usually normal may show inferior traction spur (enthesophyte) in chronic cases Ultrasound findings thickening of tendon hypoechoic areas MRI indications chronic cases surgical planning findings tendon thickening login to view 1 more bullet increased signal intensity on both T1 and T2 images loss of the posterior border of fat pad in chronic cases Treatment Nonoperative ice, rest, activity modification, followed by physical therapy indications login to view 1 more bullet technique login to view 5 more bullets cortisone injections are contraindicated due to risk of patellar tendon rupture Operative surgical excision and suture repair as needed indications login to view 3 more bullets technique login to view 3 more bullets postoperative rehab login to view 3 more bullets outcomes login to view 2 more bullets