Overview
Patellofemoral pain syndrome (PFPS) is a common cause of pain in the front of the knee around or behind the kneecap (patella). It happens when the patella does not move smoothly in the groove of the thigh bone (femur), or when the patellofemoral joint is overloaded during activities. The pain is often triggered by bending the knee under load, such as climbing stairs, squatting, or sitting with the knee bent for a long time. PFPS does not usually involve a serious injury, but it can limit activity until mechanics and strength improve.
Symptoms
People with PFPS typically feel a dull, aching, or sharp pain in the front of the knee or around the kneecap, sometimes with a grinding or "creaking" sensation. Symptoms often worsen with stairs, hills, squatting, kneeling, running, or standing up from a chair after sitting. Pain may also flare after prolonged sitting with bent knees, sometimes called the "theater sign." Some people notice a sense of instability or that the knee may "give way," usually because pain limits confident movement.
Causes
PFPS usually develops from a mismatch between how much load the patellofemoral joint experiences and how well the surrounding muscles and movement patterns control the kneecap. Common contributors include overuse, maltracking due to hip weakness or poor alignment, and tightness in structures that affect patellar motion. Less commonly, direct injury to the knee or changes in training, footwear, or activity level can overload the joint.
Risk Factors
Risk is higher in people who run, jump, or frequently climb stairs, especially after a sudden increase in training or intensity. Weak hip and thigh muscles, limited hip or knee mobility, and poor movement mechanics can increase patellofemoral stress. Being overweight can add extra load to the kneecap during bending, and certain foot mechanics such as overpronation may contribute in some people. Age and growth-related changes during adolescence can also increase susceptibility.
Prevention
You can lower your risk by gradually increasing activity and avoiding sudden spikes in running, jumping, or stair work. Strengthening the hips and thighs and improving knee control during squats, lunges, and step-downs helps the patella track more smoothly. Supportive footwear, managing body weight, and addressing flexibility or stiffness with consistent mobility work can reduce joint overload. If symptoms start, adjusting activity early and maintaining a pain-guided exercise routine can prevent prolonged flare-ups.
How the Diagnosis Is Evaluated
Clinicians usually diagnose PFPS based on your history of anterior knee pain and what activities reliably trigger it, along with a focused physical exam. The exam often checks patellar tracking, tenderness around the kneecap, hip and thigh strength, and whether pain is reproduced with squatting, stairs, or step-down testing. Imaging is not always required, but X-rays may be used to rule out arthritis or other bone problems. MRI is typically reserved for cases with red flags such as significant swelling, mechanical locking, persistent symptoms despite good conservative care, or suspicion of another diagnosis.
Nonsurgical Treatment Options
Treatment usually starts with activity modification to reduce patellofemoral overload while staying as active as you can tolerate. Physical therapy is the cornerstone and typically includes exercises to strengthen the hips, glutes, and quadriceps, along with training for better knee alignment during movement. Many people benefit from taping or bracing strategies to improve patellar tracking and reduce pain during exercise and daily activities. Short-term use of anti-inflammatory medicines like NSAIDs may help manage flare pain for some patients, but they should be used appropriately for your overall health. Foot orthotics and footwear changes can help if foot mechanics contribute to knee alignment in your case. In stubborn, well-evaluated cases, clinicians may consider injections such as corticosteroid or platelet-rich plasma (PRP), though evidence and expectations vary and these are not first-line for most patients.
When to Seek Medical Attention
Seek prompt medical attention if you have a major injury, sudden inability to bear weight, rapidly increasing swelling, or severe pain that is not improving. Get evaluated urgently if the knee locks, you cannot fully straighten it, or you develop fever or redness suggesting infection. Contact a clinician soon if symptoms persist or worsen despite several weeks of conservative care, or if you have progressive weakness, numbness, or other neurologic concerns.
Frequently Asked Questions
It often feels like aching or sharp pain in the front of the knee around or behind the kneecap, usually worse with stairs, squatting, or prolonged sitting.
Not usually; PFPS is often related to how the kneecap tracks and how loads are distributed, and it typically improves with the right strengthening and mechanics.
Surgery is not usually the first treatment; most cases improve with conservative care such as physical therapy, taping, and activity adjustment.
Next Steps
If your symptoms match PFPS and you can safely move the knee, start with a pain-guided plan that includes hip and thigh strengthening and activity modification, and consider seeing a physical therapist for individualized technique. If pain is severe, you have swelling, locking, or you are not improving after several weeks of conservative care, arrange an in-person evaluation with a sports medicine or orthopedic clinician to confirm the diagnosis and rule out other causes.