Patellar Tendinopathy

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

1. See Also
   1. Patellar Tendon Rupture
2. Pathophysiology
   1. Patellar tendon inflammation at attachment of Patellar tendon insertion at inferior pole of Patella
3. 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
4. Risk factors
   1. Running
      1. Jumping or bounding are more common overall than Running
   2. Athletes in jumping sports
      1. High jump
      2. Basketball
      3. Football
      4. Gymnastics
   3. Comorbid conditions
      1. Systemic Lupus Erythematosus
      2. Rheumatoid Arthritis
      3. Chronic Renal Failure
      4. Diabetes Mellitus
      5. Paget's Disease
   4. Other associated factors
      1. Knee Local Corticosteroid Injections
      2. Repetitive Trauma to knee extensor tendon
      3. Ankle dorsiflexion Muscle Weakness (from prior ankle injury)
5. Symptoms
   1. Anterior Knee Pain
      1. Inferior Patella
      2. Proximal Patellar tendon
   2. Timing
      1. Initially: Pain after Exercise
      2. Later: During Exercise and while at rest
6. Signs
   1. Focal Tenderness
      1. Inferior pole of Patella
      2. Patellar tendon body
   2. Strength
      1. Knee extension weakness
      2. Predisposing findings
         1. Ankle dorsiflexion weakness
         2. Hamstring tightness
         3. Heel cord tightness
         4. Quadriceps muscle tightness
   3. Pain on single leg decline squat (LR+ 4 and LR- 0.5)
      1. Extend unaffected knee
      2. Squat with affected leg
7. Differential Diagnosis
   1. Patellofemoral Pain Syndrome
   2. Patellar tendon soft tissue lesion
8. Imaging
   1. Patellar tendon Ultrasound
   2. Knee XRay
      1. Patella inferior pole irregularity
   3. MRI Knee
      1. Patellar Tendonitis may appear as false positive partial Patellar Tendon Rupture
9. Management
   1. Eccentric Exercises (decline knee bends)
      1. Flex and extend knees while standing on decline board
      2. Ankle dorsiflexion
   2. Flexibility
      1. Hamstring, heel cord and quadriceps flexibility
   3. Avoid ineffective measures (Patellar Taping, extracorporeal shock wave therapy)
   4. Surgery may be considered in refractory cases
   5. Experimental techniques
      1. Autologous blood injection into the Patellar tendon
10. Precautions
    1. Do not inject Corticosteroid (risk of Patellar Tendon Rupture)
11. Complications
    1. Patellar Tendon Rupture
12. References
    1. Madden (2010) Netter's Sports Medicine, p. 425
    2. Arnold (2018) Am Fam Physician 97(8): 510-6 [PubMed]
    3. Levine (1996) Postgrad Med 100(2): 241-246 [PubMed]