II. Pathophysiology
- Patellar tendon inflammation at attachment of Patellar tendon insertion at inferior pole of Patella
- Common cause of Anterior Knee Pain
III. Epidemiology
- Males affected more often (6:1 ratio)
- Ages 25 to 40 most often affected
-
Tendonitis without rupture occurs in teen boys
- Associated with jumping sport during growth spurt
IV. Risk factors
-
Running
- Jumping or bounding are more common overall than Running
- Athletes in jumping sports
- High jump
- Basketball
- Football
- Gymnastics
- Comorbid conditions
- Injury and Iatrogenic Causes
- Knee Local Corticosteroid Injections
- Repetitive Trauma to knee extensor tendon
- Structural predisposition
- Ankle dorsiflexion Muscle Weakness (from prior ankle injury)
- Leg Length Discrepancy
- Pes Cavus
- Quadriceps tightness or weakness
- Hamstring tightness
V. Symptoms
VI. Signs
- Focal Tenderness
- Strength
- Knee extension weakness
- Predisposing findings
- Ankle Dorsiflexion Weakness
- Hamstring tightness
- Heel cord tightness
- Quadriceps Muscle tightness
- Pain and decreased depth on single leg decline squat (LR+ 4 and LR- 0.5)
- Extend unaffected knee
- Squat with affected leg
VII. Differential Diagnosis
- Patellofemoral Pain Syndrome
- Patellar tendon soft tissue lesion
VIII. Imaging
- Patellar tendon Ultrasound
-
Knee XRay
- Patella inferior pole irregularity
- MRI Knee
- Patellar Tendonitis may appear as False Positive partial Patellar Tendon Rupture
IX. Management
- Relative rest
- Cold therapy (Cryotherapy)
- NSAIDs
-
Patellar Tendon Strap (Patellar counterforce brace)
- May decrease pain and increase function
-
Eccentric Exercises (decline knee bends)
- Flex and extend knees while standing on decline board
- Ankle dorsiflexion
- Flexibility
- Hamstring, heel cord and quadriceps flexibility
- Other non-surgical measures in refractory cases (45% of patients)
- Corticosteroid Injection
- Risk of Patellar Tendon Rupture (Exercise caution!)
- Topical Nitroglycerin Patch (one quarter of 5 mg patch)
- Extracorporeal shock wave therapy
- Corticosteroid Injection
- Avoid ineffective measures (Patellar Taping, extracorporeal shock wave therapy)
- Surgery may be considered in refractory cases
- Experimental techniques
- Autologous blood injection into the Patellar tendon
X. Complications
XI. References
- Madden (2010) Netter's Sports Medicine, p. 425
- Arnold (2018) Am Fam Physician 97(8): 510-6 [PubMed]
- Kane (2019) Am Fam Physician 100(3): 147-57 [PubMed]
- Levine (1996) Postgrad Med 100(2): 241-246 [PubMed]