Knee Pain: Causes and When to See a Knee Specialist
A guide to the most common causes of knee pain, organized by where it hurts and how it started, from Frisco orthopedic sports medicine surgeon Dr. Andrew Dold, MD.
Knee pain is one of the most common reasons people see an orthopedic surgeon. Where it hurts, how it started and what makes it worse are strong clues to the cause. Use this guide to understand the likely possibilities. Dr. Dold can then confirm the diagnosis with an exam and imaging.
- Cannot put weight on the leg after an injury, or the knee looks deformed (go to the emergency room)
- Have a hot, red, swollen knee with fever or feeling unwell
- Heard a pop and the knee swelled within a few hours
- Have a knee that locks, catches or gives way
- Still have pain after 2 to 3 weeks of rest and simple care
Pain at the front of the knee
Pain around or behind the kneecap is the most common type of knee pain in active people. It is often worse on stairs, squatting, kneeling or after sitting for a long time.
- Runner’s knee (patellofemoral pain): aching around the kneecap with running, stairs and sitting
- Patellar tendinitis (jumper’s knee): pain just below the kneecap with jumping and running
- Quadriceps tendinitis: pain just above the kneecap
- Patellofemoral arthritis and chondromalacia: grinding and pain behind the kneecap from cartilage wear
- Kneecap dislocation and instability: a kneecap that slips out of place
- Plica syndrome: catching or aching on the inner front of the knee
- Prepatellar bursitis: swelling over the front of the kneecap, often from kneeling
- Osgood-Schlatter disease: a sore bump below the kneecap in growing athletes
Pain on the inside of the knee
- Medial meniscus tear: pain along the inner joint line, often with twisting, squatting or catching
- MCL sprain or tear: pain after a blow to the outside of the knee or a twisting fall
- Knee arthritis: aching and stiffness, most often on the inner side, usually after age 50
- Pes anserine bursitis: tenderness just below the inner joint line
- Knee osteonecrosis (SONK): sudden, severe inner-knee pain, often at night, without a clear injury
Pain on the outside of the knee
- IT band syndrome: burning pain on the outer knee in runners and cyclists
- Lateral meniscus tear and discoid meniscus: outer joint-line pain, clicking or locking; discoid meniscus is most often found in children
- LCL and posterolateral corner injuries: outer-knee pain and instability after a hyperextension or a blow to the inner knee
Pain at the back of the knee
- Baker’s cyst: a tight swelling behind the knee, usually from a problem inside the joint
- PCL tear: pain at the back of the knee after a fall onto a bent knee or a dashboard injury
- Posteromedial corner injuries: back-inner corner pain, often with other ligament tears
- Hamstring strains and, rarely, a blood clot in the calf can also cause pain behind the knee. Sudden calf swelling with pain needs urgent attention.
A pop, then swelling: possible ligament or tendon injury
A pop with immediate swelling during a cut, pivot or landing is a classic sign of an ACL tear. A kneecap dislocation can feel similar. Being unable to straighten the leg against gravity after a fall or jump can mean a quadriceps tendon or patellar tendon rupture, which usually needs prompt surgical repair. Fractures, including a kneecap fracture and tibial plateau fractures, cause severe pain and trouble bearing weight.
Locking, catching or giving way
True locking, where the knee will not straighten until you wiggle it, often comes from a torn meniscus or a loose fragment from a cartilage injury or OCD lesion. Giving way usually points to a ligament injury such as an ACL tear, or to kneecap instability.
Knee pain in children and teens
Growing athletes get some problems adults don’t: Osgood-Schlatter disease, osteochondritis dissecans, discoid meniscus and kneecap instability. Knee pain in a child can also come from the hip, so the hip is always checked. See our young athletes page.
How Dr. Dold diagnoses knee pain
- A detailed history and a hands-on exam of the knee, hip and walking pattern, including ligament tests such as the Lachman test
- X-rays, usually taken at your first visit in our Frisco office
- An MRI when a ligament, meniscus, cartilage or bone injury is suspected
- Sometimes an ultrasound or a diagnostic injection
Treatment options
Most knee pain improves without surgery, with activity changes, physical therapy, bracing and, when appropriate, injections. When surgery is needed, Dr. Dold offers knee arthroscopy, ACL reconstruction, meniscus repair, cartilage restoration, osteotomy and robotic knee replacement, so your options are weighed together. See all knee conditions and knee procedures.
Why see Dr. Dold
- Board certified by the American Board of Orthopaedic Surgery, with subspecialty certification in Sports Medicine
- Fellow of the American Orthopaedic Association (FAOA), the American Academy of Orthopaedic Surgeons (FAAOS), the American College of Surgeons (FACS) and the Royal College of Surgeons of Canada (FRCSC)
- Sports medicine and arthroscopy fellowship at NYU Langone / Hospital for Joint Diseases; orthopedic residency at the University of Toronto
- Author of a JAAOS review on posteromedial corner knee injuries
- D Magazine Best Doctors (Collin County), 2019–2026 · Rated 4.9 on Google
Frequently asked questions
Why does my knee hurt going down stairs?
Pain at the front of the knee on stairs, squatting or after sitting usually comes from the joint behind the kneecap (patellofemoral pain or runner’s knee) or from cartilage wear there. Strengthening the hip and thigh muscles helps most people.
When should I see a doctor for knee pain?
Go to the emergency room if you cannot put weight on the leg after an injury or the knee looks deformed, or if it is hot, red and swollen with fever. Book a visit if the knee swelled quickly after a twist or pop, locks or gives way, or still hurts after 2 to 3 weeks of rest and simple care.
Do I need an MRI for knee pain?
Not always. A careful exam and X-rays come first. An MRI is useful when a ligament tear, meniscus tear, cartilage injury or bone bruise is suspected, or when pain has not improved with treatment.
What does it mean if my knee clicks or locks?
Painless clicking is common and usually harmless. A knee that catches or locks so you cannot straighten it fully can mean a torn meniscus or a loose piece of cartilage, and should be checked.
Can knee pain come from my hip or back?
Yes. Hip arthritis, and in children some hip conditions, can be felt in the knee, and nerve irritation from the lower back can cause pain around it. Dr. Dold checks the hip and back as part of a knee exam.
Research cited on this page
- Bachmann LM, Haberzeth S, Steurer J, ter Riet G. The accuracy of the Ottawa knee rule to rule out knee fractures: a systematic review. Ann Intern Med. 2004;140(2):121-124. PubMed
In 6 pooled studies of 4,249 adults with an acute knee injury, a simple bedside rule picked up about 98.5% of fractures, so a negative result reliably rules a fracture out. - Benjaminse A, Gokeler A, van der Schans CP. Clinical diagnosis of an anterior cruciate ligament rupture: a meta-analysis. J Orthop Sports Phys Ther. 2006;36(5):267-288. PubMed
Across 28 studies, the Lachman test was the most accurate exam test for an ACL tear (pooled sensitivity 85%, specificity 94%). - Fransen M, McConnell S, Harmer AR, et al. Exercise for osteoarthritis of the knee. Cochrane Database Syst Rev. 2015;1:CD004376. PubMed
Land-based exercise reduces knee arthritis pain and improves function, with benefits lasting at least 2 to 6 months after treatment ends and of a size comparable to anti-inflammatory medicines. - Katz JN, Brophy RH, Chaisson CE, et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis. N Engl J Med. 2013;368(18):1675-1684. PubMed
In patients with a meniscal tear and mild to moderate arthritis, function at 6 months was similar after arthroscopic surgery or physical therapy, although 30% of the therapy group went on to have surgery. - Sihvonen R, Paavola M, Malmivaara A, et al. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med. 2013;369(26):2515-2524. PubMed
For a degenerative (wear-type) medial meniscus tear without arthritis, trimming the meniscus gave results no better than a sham operation, which is why non-surgical care is tried first for these tears.
Medically reviewed by Andrew P. Dold, MD, FAOA, FAAOS, FACS, FRCSC. Last reviewed October 5, 2026. This page is general information, not medical advice.
