Does Running Increase Risk of Patellar Tendon Degeneration?
Yes, running does increase the risk of patellar tendon degeneration, particularly in athletes who engage in repetitive loading activities, with patellar tendinopathy being a common overuse injury in long-distance runners, especially women. 1
Evidence of Running-Related Risk
Running creates substantial mechanical loading on the patellar tendon that can lead to degenerative changes when load exceeds the tendon's adaptive capacity. The condition involves degeneration of normally arranged collagen fiber structure, resulting in collagen disorientation and fiber separation rather than acute inflammation. 2
Specific Loading Characteristics
- Running generates significant patellar tendon stress, with biomechanical studies demonstrating that running activities produce measurable loading peaks, loading rates, and cumulative loading impulses on the patellar tendon. 3
- Treadmill running may pose additional risk, as it results in no difference in patellofemoral joint loading compared to overground running, though the repetitive nature of both creates cumulative tendon stress. 4
- Eccentric overloading of the quadriceps muscle group during running has been identified as a major etiological factor in patellar tendinopathy development. 1
Population at Risk
Female runners face particularly elevated risk for patellar tendinopathy compared to their male counterparts. 1 The condition is highly prevalent in sports involving running and jumping, with insidious onset of load-related localized pain on the anterior knee coinciding with increased activity. 2
Biomechanical Risk Factors in Runners
- Increased pronation velocity during running contributes to patellar tendon degeneration risk. 1
- Lack of joint coordination during the running gait cycle increases mechanical stress on the patellar tendon. 1
- Progressive activity-related anterior knee pain develops as the tendon undergoes degenerative changes from repetitive loading. 5
Clinical Presentation in Runners
Most cases represent chronic tendinosis rather than acute inflammation, as runners typically present after prolonged symptoms when any acute inflammatory phase has subsided. 2 Pain is characteristically "sharp" or "stabbing" and worsens with stair navigation and prolonged sitting. 2
Diagnostic Confirmation
- Physical examination reveals pain at the inferior pole of the patella with resisted leg extension in full extension. 6
- Ultrasonography demonstrates tendon thickening and decreased echogenicity with 94% specificity, though only 58% sensitivity. 2, 6
- MRI shows chronic degenerative tendon changes with 78% sensitivity and 86% specificity. 2, 6
Prevention and Management for Runners
Eccentric strengthening exercises are the cornerstone of both treatment and prevention, as they reduce symptoms, increase strength, and promote tendon healing by stimulating collagen production and guiding normal alignment of newly formed collagen fibers. 2, 6
Specific Interventions
- Reduction of pronation velocity through orthotics and proper running shoes helps decrease mechanical stress on the patellar tendon. 1
- Balance training addresses joint coordination deficits that contribute to abnormal loading patterns. 1
- Relative rest by reducing repetitive loading activities that reproduce pain is essential, but complete immobilization must be avoided as it causes muscular atrophy. 6
Critical Pitfall
Never inject corticosteroids directly into the tendon substance, as this inhibits healing, reduces tensile strength, and predisposes to spontaneous rupture despite providing short-term symptom relief. 6
Prognosis
Approximately 80% of runners with patellar tendinopathy recover completely within 3-6 months with appropriate conservative treatment centered on eccentric loading exercises. 7, 6 Surgery is justified only after 3-6 months of well-managed conservative treatment has failed. 6