Jumper's Knee

Aka: Jumper's Knee, Patellar Tendonitis, Patellar Tendinopathy, Patellar Tendon Rupture

1. Epidemiology
   1. Males affected more often (6:1 ratio)
   2. Ages 25 to 40 most often affected
   3. Tendonitis without rupture occurs in teen boys
      1. Associated with jumping sport during growth spurt
2. Risk factors
   1. Athletes in jumping sports
      1. High jump
      2. Basketball
      3. Football
      4. Gymnastics
   2. Comorbid conditions
      1. Systemic Lupus Erythematosus
      2. Rheumatoid Arthritis
      3. Chronic Renal Failure
      4. Diabetes Mellitus
      5. Paget's Disease
   3. Other associated factors
      1. Knee Local Corticosteroid Injections
      2. Repetitive trauma to knee extensor tendon
3. Signs: Patellar Tendon Rupture
   1. Large Knee Effusion
   2. Defect between tibial tubercle and inferior Patella
   3. Difficult active knee extension
4. Differential Diagnosis
   1. Patellar Dislocation
   2. Quadriceps tendon rupture (elderly)
   3. Tibial tuberosity avulsion (adolescents)
5. Imaging: Patellar tendon rpture
   1. Insall-Salvati Ratio for Patella evaluation
      1. Distance ratio between
         1. Proximal tibial tubercle
         2. Inferior pole of the Patella
      2. Normal ratio: +1 or -0.2
   2. Interpretation: Severe Patella alta (high riding)
      1. Suggests Patellar ligament rupture
6. Management
   1. Surgical Correction within 10 days of injury
   2. Cast immobilization for 6 weeks following surgery
   3. Physical therapy
7. Management: Experimental techniques
   1. Autologous blood injection into the Patellar tendon
8. Precautions
   1. Do not inject Corticosteroid (risk of Patellar Tendon Rupture)
9. Complications: Associated with delayed surgery
   1. Quadriceps contracture shortens extensor mechanism
10. References
    1. Levine (1996) Postgrad Med 100(2): 241-246