Jumper's knee, or patellar tendinopathy if you want the clinical term, is one of the more stubborn overuse injuries in sport. Pain just below the kneecap, worse with jumping and squatting, and a tendency to drag on for months when mismanaged. The name points toward basketball and volleyball players, and those populations do get hit hardest, but it shows up in any sport that loads the knees repeatedly and hard.
What's in a name? Tendinopathy, not tendinitis
The shift from "tendinitis" to "tendinopathy" isn't just terminology. Tendinitis implies inflammation: swelling, redness, heat. Patellar tendinopathy doesn't look like that at the tissue level. The tendon isn't inflamed — it's degenerating. Collagen fibers become disorganized, new blood vessels and nerve endings infiltrate the tissue, and the structure becomes weaker. Inflammatory cells are largely absent.
This matters because anti-inflammatory treatments — NSAIDs, cortisone — target inflammation. They can blunt the pain, but they don't do anything for structural degeneration. You can feel better while the tendon continues to deteriorate. That's not a great trade.
Who gets it
Elite volleyball and basketball players see prevalence rates as high as 40-50%. Track and field athletes, gymnasts, soccer players are also commonly affected. The typical onset is between 15 and 30, though older athletes aren't immune.
The mechanism is repetitive eccentric loading. Every jump landing requires the quadriceps to contract eccentrically — lengthening under tension — to absorb force. Do that thousands of times without adequate recovery, and the tendon starts breaking down faster than it can repair itself.
The anatomy
The quadriceps muscles run down the front of the thigh and converge into the quadriceps tendon just above the kneecap. The tendon wraps around the patella, which functions as a pulley to increase mechanical leverage, then continues as the patellar tendon, attaching to the tibial tuberosity on the front of the shin.
Jumper's knee specifically affects the patellar tendon at the inferior pole of the patella — the bottom of the kneecap, where the tendon originates. That's where stress concentrates. Quadriceps tendinopathy can develop above the patella, but it's less common in jumping athletes and presents differently.
Diagnosis
Diagnosis is usually clinical. History plus physical exam is often enough. The characteristic finding is tenderness at the inferior pole of the patella on palpation, and a single-leg decline squat typically reproduces the pain.
Imaging helps when the picture is unclear or you need to rule something out. Ultrasound can show tendon thickening and structural disorganization. MRI is useful for excluding patellofemoral pain syndrome, fat pad impingement, or stress fractures. Worth knowing: imaging findings don't correlate reliably with symptoms. Significant structural changes on MRI sometimes accompany mild pain, and near-normal scans sometimes accompany severe limitation. For tracking functional severity over time, the VISA-P questionnaire is more useful than repeat imaging.
Treatment: load it, don't rest it
The treatment that actually works is progressive tendon loading. Not rest — load.
The classic approach is the Alfredson eccentric decline squat protocol. Stand on a 25-degree decline board, lower slowly on one leg, return to the top using both legs, and repeat: 3 sets of 15, twice a day, every day, for 12 weeks. Mild pain during the exercise is expected and acceptable. The whole point is that tensile load — even uncomfortable load — drives tendon remodeling and collagen synthesis. The protocol has a solid evidence base. It also demands genuine commitment, because it's painful in the early weeks and has to happen every day without exception.
Heavy slow resistance (HSR) training has become a mainstream alternative, and for many patients it's easier to stick to. Bilateral squats, leg presses, or hack squats with heavy weights — roughly 60-80% of one-rep max — performed at a slow tempo (about 3 seconds each direction), 3-4 sets of 6-8 reps, two or three times per week. The load stimulus appears similar to eccentric training, with better compliance and less pain flare early on.
Most programs now use both. HSR first to build a foundation and reduce irritability, then a shift toward more sport-specific eccentric loading and plyometrics as tolerance improves. Either way, plan for 3-6 months of committed rehabilitation, often longer for chronic cases. Progress isn't linear.
Load management
This is where most athletes sabotage their own recovery. The principle is simple enough: keep training load within what the tendon can currently tolerate, while still applying enough stimulus to drive adaptation. In practice, especially mid-season, this is genuinely difficult.
Reducing jump volume is usually necessary early on. Cycling and swimming maintain fitness without loading the patellar tendon. Practice intensity often has to drop temporarily. A useful working rule: if pain during an activity is noticeably elevated, or lingers more than 24 hours afterward, you've exceeded the tendon's current tolerance. Scale back and build up more gradually.
Cortisone
The appeal of a cortisone injection is obvious — it can substantially reduce pain within days. But cortisone inhibits collagen synthesis and weakens tendon tissue. For a condition already defined by structural degradation, that's exactly the wrong direction. Research comparing cortisone to exercise therapy has consistently shown worse long-term outcomes for the injection group: higher recurrence rates, more structural damage over time. Repeated injections carry real risk of tendon atrophy and rupture.
A single injection to break a severe pain cycle so rehabilitation can begin is occasionally defensible. As a primary treatment strategy, cortisone tends to create a window of pain relief while making the underlying problem worse.
PRP
PRP involves concentrating your own platelets and injecting the growth-factor-rich solution into the tendon to try to stimulate healing. The biology is reasonable. The clinical results are inconsistent. Some trials show modest benefit in chronic cases that haven't responded to exercise rehab; others find no meaningful advantage over placebo. The honest answer is that we don't yet have reliable evidence that PRP significantly outperforms a well-executed loading program.
It's also expensive ($500-$2000+ per injection, rarely covered by insurance) and should be considered only after genuine, sustained exercise rehabilitation has been attempted over several months. If you're exploring it, make sure the conversation includes an honest account of the current evidence, not just optimism about growth factors.
Getting back to your sport
Pain-free rehab exercises don't mean the tendon is ready for full competition. Return to sport has to be tested, not assumed.
Practical benchmarks: pain during sport-specific movements should be minimal and not worsening with progressive load. Quad strength should be within about 10% of the uninjured side, testable with single-leg squat assessment or formal dynamometry. Landing mechanics matter independently of strength — poor movement patterns under load are a strong predictor of recurrence regardless of how the numbers look.
The progression is gradual by necessity. Straight-line running before lateral movement. Submaximal jumping before maximal effort. Reduced-intensity training before full competition. For high-level jumping athletes, a genuine return to unrestricted competition typically takes six months to a year from the start of structured treatment. Chronic cases often take longer.
If you've had pain below the kneecap for more than a few weeks and it's limiting your training, see a sports medicine physician or orthopedic surgeon sooner rather than later. Patellar tendinopathy responds well to proper treatment when caught early. After years of inadequate management, it becomes a different problem entirely.
