Patellofemoral pain syndrome

Overview

Patellofemoral pain syndrome (PFPS), often referred to as “runner’s knee,” is a common musculoskeletal condition that causes pain around or behind the kneecap (patella), especially during activities that involve knee bending. It is frequently seen in athletes, particularly runners, cyclists, and people engaged in sports that involve jumping or squatting. However, it can also affect non-athletes and individuals with sedentary lifestyles. PFPS is not caused by a specific structural injury but is instead the result of biomechanical imbalances and overuse, making it a functional pain syndrome rather than a structural disorder. Although the condition is typically benign, it can become chronic and significantly limit physical activity if not managed properly.

Causes

Patellofemoral pain syndrome arises from abnormal tracking of the patella within the femoral groove during knee movement. Several contributing factors can lead to this condition:

• Overuse: Repetitive knee motion during activities such as running, squatting, or stair climbing can irritate the patellofemoral joint.

• Muscle imbalances: Weakness or poor coordination of the quadriceps, gluteal, or hip muscles can cause improper patellar alignment.

• Poor biomechanics: Flat feet (pes planus), inward knee collapse (valgus), and abnormal gait patterns increase stress on the patellofemoral joint.

• Tight soft tissues: Tight hamstrings, iliotibial band (ITB), or lateral retinaculum can pull the patella out of alignment.

• Improper footwear: Worn-out or unsupportive shoes can alter lower limb alignment during movement.

• Sudden changes in activity: An abrupt increase in training intensity, duration, or surface type can contribute to PFPS.

Symptoms

The primary symptom of PFPS is a dull, aching pain in the front of the knee, often localized around or behind the kneecap. The pain tends to worsen with activities that put pressure on the patellofemoral joint. Common symptoms include:

• Pain during squatting, kneeling, running, or stair climbing (especially going down stairs)

• Discomfort after sitting for long periods with bent knees (also called “theater sign”)

• A sensation of the knee “giving way” during activity

• Crepitus or a grinding feeling when bending or straightening the knee

• Mild swelling or tenderness around the patella

Symptoms often develop gradually and may affect one or both knees.

Diagnosis

PFPS is diagnosed primarily through clinical evaluation, as imaging is usually not necessary unless other conditions are suspected. The diagnostic approach includes:

• Medical history: Review of activity levels, onset of symptoms, and prior injuries

• Physical examination: Assessment of patellar tracking, muscle strength, range of motion, and biomechanical alignment

• Special tests:

  • Patellar compression test: Pressing the patella against the femur while the patient contracts the quadriceps to reproduce pain

  • Clark’s test: Resisting patellar movement while the patient contracts the quadriceps

• Imaging studies (if needed): X-rays may be used to rule out arthritis or structural abnormalities. MRI may be considered in persistent cases to assess soft tissue or cartilage damage.

Treatment

The treatment of PFPS is non-surgical in most cases and focuses on pain relief, activity modification, and correcting biomechanical issues. The main components of treatment include:

Conservative Management:

• Rest and activity modification: Reducing or avoiding aggravating activities like running, squatting, or stairs until symptoms improve

• Physical therapy: A supervised program focusing on:

  • Strengthening the quadriceps, glutes, and hip abductors

  • Stretching tight muscle groups such as hamstrings and ITB

  • Improving balance and neuromuscular control

• Ice therapy: Applying ice after activity to reduce inflammation

• Nonsteroidal anti-inflammatory drugs (NSAIDs): For temporary relief of pain and swelling

• Patellar taping or bracing: To assist in patellar tracking and reduce stress on the joint

• Foot orthotics: Custom or over-the-counter inserts may help correct abnormal foot biomechanics

Surgical Intervention:

Surgery is rarely needed but may be considered in severe or unresponsive cases. Options include:

• Arthroscopic debridement or lateral release

• Realignment procedures for severe tracking abnormalities

Prognosis

With appropriate treatment, the prognosis for patellofemoral pain syndrome is generally excellent. Most individuals experience significant improvement within a few weeks to months of starting conservative management. Adherence to physical therapy and biomechanical correction is essential to prevent recurrence. However, if left untreated, PFPS can become a chronic condition and lead to functional limitations or progression to patellofemoral osteoarthritis. Early intervention, education on activity modification, and long-term maintenance exercises are key to achieving a full recovery and preventing future episodes.