Patellar Tendinopathy in Runners: Why Your Knee Hurts Below the Kneecap
Understanding the Patellar Tendon
The patellar tendon — also called the patellar ligament in some contexts — runs from the inferior pole of the kneecap (patella) to the tibial tuberosity at the top of the shin. It is the structure your quadriceps pull through to extend the knee during running, jumping, and stair descent. Every step a runner takes loads this tendon; over the course of a training week, the cumulative mechanical stress is substantial.
Patellar tendinopathy — commonly called jumper's knee or patellar tendonitis — develops when load exceeds the tendon's capacity to recover. At the cellular level, the normal organized collagen structure of the tendon is replaced by disorganized, mechanically inferior tissue. This degenerative process, rather than pure inflammation, is why the condition responds poorly to treatments that target inflammation alone (such as corticosteroid injections) and why it often persists for months without the right rehabilitation approach.
Runners commonly develop this condition at the inferior pole of the patella, where mechanical stress is highest, particularly during downhill running and high-cadence work.
Who Is at Risk and Why
Several factors increase a runner's risk of developing patellar tendinopathy:
Training load errors. Rapid increases in weekly mileage, speed work, or hill running are the most common triggers. Tendons adapt more slowly than cardiovascular fitness, so runners who progress their training quickly may outpace the tendon's capacity to remodel.
Quadriceps and hip weakness. Weakness in the quadriceps shifts proportionally more load onto the patellar tendon during each foot strike. Weak hip abductors cause the knee to adduct under load, altering the mechanical environment at the patellar tendon attachment.
Surface and footwear. Running predominantly on hard surfaces with inadequate footwear increases cumulative tendon stress. Shoes with excessive heel drop may also alter the biomechanics of knee loading.
Body composition. Higher body weight increases the absolute force transmitted through the patellar tendon, particularly during the eccentric loading phase of each step.
How It Is Diagnosed
Patellar tendinopathy is primarily a clinical diagnosis. Pain localized to the inferior patellar pole that is reproducible with palpation, worsens during or after running, and is aggravated by activities that load the knee in a bent position (stairs, squats, prolonged sitting) is characteristic. The pain often follows a predictable pattern: mild stiffness at the start of a run that warms up, returning as pain after the run.
Ultrasound or MRI can confirm the diagnosis, identify the extent of tendon degeneration, and rule out other causes of anterior knee pain such as patellar stress fracture, patellofemoral syndrome, or Hoffa's fat pad impingement. Imaging is particularly useful when the diagnosis is uncertain or when symptoms are not responding as expected.
Treatment That Works
Progressive tendon loading is the foundation of evidence-based patellar tendinopathy treatment. Isometric quadriceps exercises (held contractions at a fixed joint angle) provide immediate pain relief and begin mechanically stimulating the tendon. These progress to isotonic loading — heavy slow resistance training through full range — and eventually to plyometric and running-specific loading.
The eccentric single-leg decline squat, performed on a 25-degree incline board, has strong clinical evidence for patellar tendinopathy and remains a core exercise in most rehabilitation protocols. It places maximum load on the tendon at its most critical point in the movement arc.
Modification of training load must accompany rehabilitation. Complete rest is rarely beneficial — the tendon needs load to remodel — but reducing high-tendon-load activities (downhill running, sprinting, plyometrics) while maintaining lower-load training allows healing without complete detraining.
Corticosteroid injections provide short-term pain relief but have not been shown to improve long-term outcomes and may temporarily weaken tendon tissue. Platelet-rich plasma (PRP) injections show more promise for recalcitrant cases, though evidence remains mixed. Surgery is reserved for a small minority of patients who fail at least six months of supervised rehabilitation.
If you're experiencing knee pain below the kneecap, the specialists at Maryland Orthopedic Specialists can help. Call (301) 515-0900 or [schedule an appointment online](https://www.mdorthospecialists.com/contact).
