Patellar tendinopathy: the jumping knee

Patellar tendinopathy is degeneration of the patellar tendon at its attachment to the inferior pole of the patella. It is common in sports involving repetitive jumping and landing, basketball, volleyball, football, and athletics, but also develops in runners with high training volumes.

The presenting symptom is anterior knee pain directly at the tendon insertion, sharp with activity and characteristically worse with sitting for extended periods and with first steps after rest. It is not the same as patellofemoral pain, which involves the kneecap joint surface rather than the tendon.

The patellar tendon absorbs the eccentric load of landing and deceleration. In jumping athletes, the cumulative volume of this eccentric load can exceed the tendon's capacity to remodel, producing the same collagen disorganisation seen in Achilles tendinopathy.

Training load spikes (pre-season intensification, sudden increase in jump volume, hard court surfaces after a soft surface period) are the most common precipitating factors. Poor quadriceps strength, hip control deficits, and ankle stiffness all increase tendon load per landing.

Stretching the quadriceps loads the patellar tendon at its inferior pole through compression, the primary aggravating mechanism. This is why quad stretching, which is frequently recommended, typically makes the condition worse in the reactive phase.

Rest reduces pain by removing the stimulus. It does not restore tendon capacity. The tendon returns to full training in the same degenerated state, and the condition recurs.

Isometric quad holds (wall sit at 70–90 degrees) are the entry point, they provide mechanical stimulus with minimal compressive loading at the insertion. From there, heavy slow resistance (leg press, Spanish squat, bilateral and single-leg variations) provides the progressive stimulus for collagen remodelling.

Decline squats are a specific tool for patellar tendinopathy, the 25-degree decline shifts load to the quadriceps and reduces compressive force at the patella tip, allowing earlier loading of the tendon.

Return criteria: pain-free single-leg decline squat, no pain the morning after training, symmetric quadriceps strength. Plyometric loading (jumping, landing) is the last component to return, as it produces the highest peak tendon load.