What causes patellar tendinopathy and how is it treated?

Patellar Tendinopathy: Causes and Treatment

Primary Cause

Patellar tendinopathy is caused by repetitive loading and overuse of the patellar tendon, leading to degenerative collagen breakdown rather than inflammation—this is a chronic degenerative condition (tendinosis), not an inflammatory one (tendinitis). 1

Pathophysiology and Risk Factors

• The condition results from collagen disorientation, fiber separation, mucoid degeneration, and necrosis at the osteotendinous junction, most commonly at the inferior pole of the patella 2, 3
• Repetitive jumping and explosive activities (basketball, volleyball) are the primary mechanical triggers, earning it the name "jumper's knee" 4, 5
• The tendon's relative hypovascularity predisposes it to hypoxic degeneration, contributing to the pathology 1
• Multifactorial contributors include improper technique, anatomic misalignment, weakness, uneven training surfaces, and improper footwear 2

Clinical Presentation

• Activity-related anterior knee pain at the inferior pole of the patella, worsened by stairs, prolonged sitting, and jumping 2, 4
• Physical exam reveals pain with resisted leg extension in full extension and a positive decline squat test that reproduces symptoms by loading the tendon 4, 6
• Palpable tenderness and sometimes thickening at the inferior patellar pole 2

Treatment Algorithm

First-Line Conservative Management (3-6 months minimum)

Eccentric strengthening exercises are the cornerstone of treatment and should be initiated immediately, as they reverse degenerative changes by stimulating collagen production and guiding proper fiber alignment 1, 2, 4

• Relative rest: Reduce repetitive loading activities (jumping, stairs) that reproduce pain, but avoid complete immobilization which causes atrophy and deconditioning 2, 4
• Deep transverse friction massage to reduce pain 2, 4
• Cryotherapy: Apply ice through a wet towel for 10-minute periods for acute pain relief 1, 2, 4

Pain Management

• NSAIDs (topical preferred over oral) for short-term pain relief only—they do not alter long-term outcomes but topical formulations eliminate gastrointestinal hemorrhage risk 1, 4
• Avoid corticosteroid injections into the tendon substance—while they may provide short-term relief, they inhibit healing, reduce tensile strength, and predispose to spontaneous rupture 2, 4
• Corticosteroid iontophoresis (not direct injection) can be effective for pain and function 2, 4

Expected Outcomes

• Approximately 80% of patients fully recover within 3-6 months with appropriate conservative treatment 1, 2, 4

Surgical Intervention

Surgery should only be considered after 3-6 months of well-managed conservative treatment has failed 1, 2, 4, 6

• Surgical techniques include open or arthroscopic excision of abnormal tendinous tissue and longitudinal tenotomies to release scarring and fibrosis 4, 6
• No high-quality evidence favors open versus arthroscopic approaches 3
• Surgery is particularly indicated when partial tears exceed 50% of tendon thickness or tendon thickness exceeds 8.8 mm 3

Critical Pitfalls to Avoid

• Do not mislabel this as "tendinitis"—it is a degenerative condition (tendinosis), not inflammatory, which fundamentally changes treatment approach 1, 2
• Never inject corticosteroids directly into the tendon—this is the single most important caveat, as it causes tendon weakening and rupture risk despite temporary symptom relief 2, 4
• Do not proceed to surgery prematurely—an adequate 3-6 month trial of conservative treatment is mandatory 4, 6
• Do not prescribe complete rest or immobilization—this worsens outcomes through deconditioning 2, 4
• If multiple tendons are symptomatic, evaluate for underlying rheumatic disease 4