When your knee hurts, the first question that matters is where exactly the pain is located. Patellar tendonitis — often called jumper’s knee — is just one of many knee conditions that cause pain in the front of the knee. But because symptoms overlap with injuries like patellofemoral pain syndrome, chondromalacia, or fat pad impingement, misdiagnosis is common. The wrong treatment path can be a big mistake, as recovery can drag on for months or even years.
If you’ve struggled to pinpoint what’s going on with your knee, keep reading. You’ll see how patellar tendonitis compares with other common conditions and why getting this right is essential for healing.
What Patellar Tendonitis (Jumper’s Knee) Feels Like
Patellar tendonitis is defined by pain in the patellar tendon, usually right where the tendon attaches to the kneecap. The pain is load-related: the harder or deeper you push (jumping, running, squatting), the sharper it gets.
- Early stage: pain only during or after activity.
- Progressing: pain before activity, sometimes easing as you warm up.
- Advanced stage: constant pain interfering with daily life.
A simple self-test often used in clinics is the single-leg decline squat: standing on a slanted surface and squatting on one leg. If this reproduces your familiar tendon pain just below the kneecap, patellar tendonitis is very likely.
👉 To learn why some people get stuck with tendon pain for years and what to do differently, I share a free Tendonitis Insights Course you can join at the end of this page.
Patellar Tendonitis vs Patellofemoral Pain Syndrome (PFPS)
PFPS pain is felt behind or around the kneecap, not directly in the tendon. Sitting with bent knees, climbing stairs, or squatting makes it worse. Clicking or grating sounds are common.
- PFPS pain: behind/around kneecap, often bilateral.
- Patellar tendonitis pain: directly in tendon, usually one spot.
Both injuries can feel similar during exercise, which is why many people confuse them. But the location of pain is the key difference. Further, patellar tendonitis is more common in jumping sports, whereas PFPS is more likely to occur in running sports.
Patellar Tendonitis vs Chondromalacia Patellae (CMP)
CMP is damage or irritation of the cartilage under the kneecap. Symptoms overlap heavily with PFPS: front knee pain and joint noises. A positive Clark’s test (kneecap compression) may indicate CMP, but accuracy is limited.
Unlike tendonitis, CMP pain is not always linked to explosive loading. It may linger even at rest, and imaging (MRI) only reliably shows later stages.
Chondromalacia will present with more of a dull pain that’s deeper inside the joint, rather than the sharp pain directly in the tendon, at the lower pole of the kneecap.
Patellar Tendonitis vs Fat Pad Impingement
In fat pad impingement, the pain is usually burning or aching at the front of the knee and worsens in full extension (straight leg). Patients often describe snapping or catching sensations.
The big difference: patellar tendonitis pain gets worse with load and jumping, while fat pad pain often shows up simply when standing straight or walking downstairs.
Patellar Tendonitis vs IT Band Syndrome
IT band syndrome pain is on the outer side of the knee. It’s sharp or stabbing and often appears after a certain mileage while running. It fades with rest but comes back quickly once you resume activity.
Patellar tendonitis, on the other hand, does not suddenly flare at a set mileage. Instead, it builds with jumping and explosive activity. Further, you will feel it at the front of the knee and not the side.
Patellar Tendonitis vs Quadriceps Tendinopathy
Quadriceps tendinopathy pain sits above the kneecap, where the quadriceps tendon inserts. It worsens with deep knee flexion or resisted extension.
- Patellar tendonitis: below kneecap.
- Quadriceps tendinopathy: above kneecap.
This top/bottom distinction is a quick way to tell them apart.
Patellar Tendonitis vs Osgood Schlatter & Sinding-Larsen-Johansson
Both are youth overuse injuries that occur mostly in boys, so if you’re 16+ or female, you’re likely dealing with something else.
- Osgood Schlatter: pain at top of the shinbone, tendon attachment visibly enlarged.
- Sinding-Larsen-Johansson: pain at the lower pole of the kneecap. This one is more difficult to tell apart from patellar tendonitis and may require imaging.
Patellar tendonitis usually appears later, in late teens or adulthood, and pain location is more precise within the tendon.
Other Conditions That Mimic Patellar Tendonitis
Several knee issues can feel like tendonitis at first glance:
- Plica syndrome: snapping and medial pain.
- Meniscus tears: joint-line pain and catching.
- Osteoarthritis: stiffness, joint noises, and progressive disability.
- Patellar maltracking: kneecap moves laterally, sometimes painless but visible.
This overlap is why diagnosis is often frustrating and recovery so slow.
Quick Comparison Table: Patellar Tendonitis vs Other Knee Conditions
| Condition | Pain Location | Typical Trigger | Key Sign |
| Patellar Tendonitis | Below kneecap (patellar tendon) | Jumping, squatting, explosive sports | Decline squat pain |
| PFPS | Behind/around kneecap | Sitting, stairs, squats | Clicking/grating |
| Chondromalacia | Under kneecap | Load or rest | Joint noises, weak quad |
| Fat Pad Impingement | Front of knee, burning pain | Full extension, standing | Snapping, effusion |
| IT Band Syndrome | Outer knee | Running, downhill walking | Sharp lateral pain |
| Quadriceps Tendinopathy | Above kneecap | Deep flexion, resisted extension | Tender upper kneecap |
| Osgood Schlatter | Top of shinbone | Squatting, running (youth) | Enlarged tendon attachment |
Why the Right Diagnosis Matters
Choosing the wrong path can mean months of wasted rehab. For example, if you treat PFPS as tendonitis, you may overload the wrong tissues and make things worse. If you treat fat pad impingement as CMP, you may miss the burning pain trigger in full extension.
Correct diagnosis is the first step toward recovery. And understanding the stages of tendonitis is the second.
The Stages of Patellar Tendonitis
Tendon pain follows a continuum:
- Reactive stage – swelling and pain flare with new load.
- Disrepair – tendon structure starts to change.
- Degenerative – long-term changes, persistent pain.
Each stage requires a different approach. That’s why some people never heal — they’re applying the wrong rehab strategy for their stage.
👉 In my Tendonitis Insights Course, I explain the continuum model in plain language and show you which exercises are right for each stage.
Take the Next Step Toward Clarity and Recovery
👉 That’s why I created the free Tendonitis Insights Course — so you don’t stay stuck with pain. It’s based on 14 years of research and the recovery stories of thousands of athletes.
See you in the course.
