The short answer
- Knee pain is a symptom, not a diagnosis. The spot you can point to narrows the list more than anything else you can do at home.
- Pain around the kneecap is the most common kind in runners, and the first moves are strength work and a temporary cut in the loads that hurt.
- Pain on the outside that arrives at the same point in every run behaves like IT band syndrome and is handled differently.
- A small tender spot on bone that gets worse run by run, or hurts when you hop, is the one pattern that means stop and get it checked.
- Scans find wear in plenty of knees that never hurt, so an MRI rarely settles the question by itself.
Knee pain is a symptom, not a diagnosis. The knee is one joint, but the things that go wrong in it behave differently enough that the same advice can't cover them. Running through one of them costs you a week. Running through another costs you a season.
You can get a long way at home with two questions. Where exactly does it hurt, and when in the run does it show up?
Where does it hurt?
Put one finger on the sore spot. If you can cover it, that tells you more than any test you can do to yourself, because no single clinical test is accurate enough to name the problem on its own1.
Where the pain sits
- 1Around or behind the kneecap
- 2Outside of the knee, just above the joint line
- 3Just below the kneecap, on the tendon
- 4On the joint line, inside or outside
- 5One small tender spot on the bone
1. Around or behind the kneecap
This is patellofemoral pain, which had the highest prevalence of any injury in a systematic review of running injury studies2. The pain is usually vague, hard to point to with one finger, and felt around or behind the kneecap. It shows up on stairs, on downhills, in a deep squat and after sitting for a long time with the knee bent3.
The first moves are a temporary cut in the loads that hurt most, and strength work. The international expert panel on this problem recommended exercise therapy, especially hip-focused and knee-focused exercise combined, along with foot orthoses for some people. Joint mobilisation on its own and electrophysical agents were not recommended4. Our guide to kneecap pain has the full plan.
2. Outside of the knee, just above the joint line
Pain over the bony bump on the outside of the knee that builds during a run, is worse downhill, and eases when you walk with a straighter knee fits IT band syndrome5. It tends to arrive at the same point in every run, which is both its signature and the thing you use to steer the rehab. Our guide to IT band syndrome has the full plan.
3. Just below the kneecap, on the tendon
Patellar tendinopathy sits in a spot you can cover with a fingertip, at the lower tip of the kneecap. It hurts in proportion to how hard the knee extensors are working, and it is worst in activities that store and release energy in the tendon, such as jumping, deep squats and fast changes of direction6. It is more of a jumping-sport problem than a distance-running one, so in runners it usually turns up after hill repeats, plyometrics or a new gym programme.
Tendons respond to progressive loading rather than rest, and the rehab is slow and unglamorous6. The Achilles article explains the principles, and they transfer.
4. On the joint line, inside or outside
A tender line where the two bones meet, sometimes with catching, clicking or swelling that comes and goes, points at the meniscus or the joint surface. If it started with a twist and the knee locked or swelled within hours, that needs an examination. If it came on gradually in your thirties or later, a tear on a scan is a common finding rather than a verdict, and training usually beats surgery as a first step. Our meniscus article covers the trials.
5. One small tender spot on the bone
Bone is the exception to everything else on this page. The pattern is pain over bone that you can press on and reproduce, that arrives earlier in every run, and that can hurt when you hop or even at night. Bone stress injuries come from the load being added faster than the bone adapts7.
This one does not get a trial run. Before running again after a tibial bone stress injury, the usual criteria are that the bony tenderness has resolved and walking is pain-free8. Our stress fracture guide covers the rest.
Then watch how it behaves
Location narrows the list. How the pain behaves over a run and the next day tells you whether you can keep running while you sort it out.
- During the run
- Soft tissue patternOften eases in the first ten minutes, or arrives at a predictable point
- Bone patternComes on earlier each run and keeps building
- Pressing on it
- Soft tissue patternSore over a broad area, or nothing to feel from outside
- Bone patternA small spot on the bone, sore to press every time
- Hopping
- Soft tissue patternUncomfortable, but you can do it
- Bone patternSharp, and you don't want to repeat it
- Next morning
- Soft tissue patternBack to your usual level
- Bone patternStill sore, and sore to walk on
- Over weeks
- Soft tissue patternRoughly stable, or improving with the work you're doing
- Bone patternSteadily worse, whatever you do
The right column is the one to act on. The left column is workable with training changes, and our article on soreness sets out the limits we use.
What to do in the first two weeks
Whichever of the first four you have, the opening moves are similar, and none of them is a full stop.
- Cut the loads that provoke it most, rather than everything. For most knees that means hills, stairs, deep squats and speed work before easy distance.
- Find the amount you can run that leaves the knee at its usual level the next morning, and hold it for a week before adding.
- Start strength work twice a week for the hip and the knee. Split squats, step-ups, leg presses or heavy leg extensions, plus calf work, all count.
- Change one thing at a time, so you know what the knee reacted to.
What a scan can settle
Not as much as most runners expect. Findings that look like damage are common in knees that feel fine.
A scan earns its place when the history and the examination point to something specific, when the knee locks or gives way, or when the pain isn't following the pattern it should. It rarely earns its place as the first step.
How long these take
The realistic ranges differ more than most runners expect.
Patellofemoral pain has a reputation for settling on its own that the data don't support. When two trials were followed up years later, 34 of the 60 people who responded, 57%, reported an unfavourable recovery 5 to 8 years after diagnosis. Only a fifth of the original participants answered, so the exact figure is shaky, but it is far from a self-limiting problem. Of those who had knee x-rays, 48 of 50 showed no osteoarthritis, and a longer history before treatment predicted the worse outcomes10.
Bone is more predictable, and the site matters. Pooled across 76 studies, return to sport took about 44 days after a bone stress injury of the posteromedial shin and about 107 days after one in the femoral neck. More than 90% of athletes got back to their sport11.
When to get it checked
The first three point to the joint itself and need an examination. A single tender spot on bone needs one before your next run.
For the rest, the work is naming the problem, then giving it the right dose for long enough. That is most of what we do with runners, and it is usually less dramatic than it feels at the start.