"Where Is My Knee Pain Coming From? Understanding Patellofemoral Pain Syndrome (Runner’s Knee)"

Knee pain is a common complaint among people of all ages. If you experience discomfort at the front of your knee, especially while walking downstairs, squatting, or sitting for long periods, you may be suffering from Patellofemoral Pain Syndrome (PFPS) — also known as runner’s knee.

What Is Patellofemoral Pain Syndrome?

Patellofemoral Pain Syndrome refers to pain around or behind the kneecap (patella) where it connects with the thigh bone (femur). It is one of the most frequent causes of anterior knee pain, especially in athletes, runners, young adults, and individuals who perform repetitive knee movements.

Common Causes of Patellofemoral Pain Syndrome

Several factors can contribute to PFPS, including:

• Overuse or repetitive stress (e.g. running, jumping, or squatting)

• Muscle imbalances around the hip and thigh

• Poor patellar tracking (the kneecap doesn’t move smoothly)

• Flat feet or poor footwear

• Tight hamstrings or iliotibial (IT) band

• Improper alignment of the legs or kneecap

• Sudden increase in physical activity or training intensity

Symptoms of Patellofemoral Pain Syndrome

If you have PFPS, you might experience:

• Dull, aching pain in the front of the knee

• Pain that worsens with:

  • Climbing or descending stairs

  • Squatting

  • Sitting for long periods ("theater sign")

  • Running or jumping

• Grinding or popping sounds during knee movement

• Tenderness around the kneecap

Diagnosis: How Is PFPS Identified?

Diagnosis is usually clinical, based on symptoms and physical examination. A physiotherapist or physician will assess:

• Knee alignment and tracking

• Muscle strength and flexibility

• Gait and posture

• Specific tests (e.g. Clarke’s test)

Imaging (like X-rays or MRI) may be used to rule out other conditions.

When to See a Doctor or Physiotherapist

If your pain persists for more than a few weeks or worsens despite rest, consult a professional. Early intervention helps prevent chronic pain and long-term joint damage.

Sinding-Larsen-Johansson Syndrome (SLJS)

While Patellofemoral Pain Syndrome is a common cause of anterior knee pain, it’s important to consider other potential diagnoses—especially in adolescents. Sinding-Larsen-Johansson Syndrome (SLJS) is a growth-related overuse injury that affects the inferior pole of the patella, typically seen in active teenagers during growth spurts.

What Is SLJS?

SLJS is an osteochondrosis, where repetitive strain causes inflammation at the point where the patellar tendon attaches to the lower part of the kneecap. It’s sometimes referred to as a “teenager’s jumper’s knee.”

Key Features:

• Seen in active adolescents, especially those in jumping or sprinting sports.

• Localized pain and swelling at the bottom of the kneecap.

• Pain worsens with physical activity and improves with rest.

• Tenderness over the inferior patella upon palpation.

Diagnosis:

Clinical examination is usually sufficient, but diagnostic ultrasound scan show calcification at the patellar tendon insertion point along with tendon thickening and inflammation.

Management:

• Relative rest and activity modification.

• Ice therapy for symptom relief.

• Physiotherapy focused on quadriceps and hamstring flexibility, as well as patellar tendon unloading techniques.

• Gradual return to sports once pain subsides.

Proximal Patellar Tendinopathy & Enthesopathy with Hypervascularity

Not all anterior knee pain is due to Patellofemoral Pain Syndrome. Another common cause in active individuals is Proximal Patellar Tendinopathy, often seen with enthesopathy — an overuse-related condition affecting the tendon’s attachment site on the patella.

What Is It?

Proximal patellar tendinopathy (commonly known as Jumper’s Knee) involves degeneration and irritation at the origin of the patellar tendon. When this is accompanied by enthesopathy, the tendon’s attachment point becomes inflamed, sometimes with hypervascularity—increased abnormal blood flow seen on diagnostic ultrasound.

Symptoms:

• Localised pain at the inferior pole of the patella

• Pain worsens with jumping, running, squatting, or prolonged sitting

• Tenderness at the tendon insertion site

• Morning stiffness or pain at the start of activity

Diagnostic Imaging:

• Musculoskeletal ultrasound may reveal:

  • Thickened proximal patellar tendon

  • Hypoechoic (dark) areas indicating degeneration

  • Hypervascularity on Doppler imaging

  • Enthesopathic changes (calcification or thickening at the bone-tendon interface)

Ultrasound-Guided High-Volume Stripping Injection

For chronic cases not responding to physiotherapy, High-Volume Stripping (HVS) is a cutting-edge, ultrasound-guided injection technique used to treat patellar tendinopathy—especially when hypervascularity is present.

What Is High-Volume Stripping?

• A minimally invasive procedure using a high volume (typically 10–40 mL) of fluid (saline + local anaesthetic, sometimes corticosteroid) injected around the tendon to:

  • Mechanically strip away neovessels and nerve ingrowth

  • Reduce pain-generating structures

  • Improve tendon healing environment

Benefits:

• Reduces pain and tenderness associated with neovascularisation

• Can enhance rehabilitation outcomes when combined with physiotherapy

• Promotes tendon recovery without surgical intervention

This advanced treatment is particularly beneficial for athletes or active individuals suffering from chronic proximal patellar tendinopathy with confirmed hypervascularity on imaging.

Ultrasound-Guided High-Volume Stripping Injection

Treatment Options for Patellofemoral Pain Syndrome

The good news: PFPS is treatable with conservative management. Here’s what works best:

1. Physiotherapy

The cornerstone of treatment. Focuses on:

• Strengthening the quadriceps, hip abductors, and glutes

• Stretching tight muscles (IT band, hamstrings)

• Correcting movement patterns

2. Activity Modification

• Reduce high-impact activities temporarily

• Avoid deep squats or stairs until pain subsides

3. Footwear & Orthotics

• Supportive shoes or custom orthotics for flat feet can improve alignment

4. Taping or Bracing

• Patellar taping (e.g. McConnell taping) may help correct tracking and reduce pain

5. Ice and NSAIDs

• Apply ice post-activity and use non-steroidal anti-inflammatory drugs (if advised)

Can It Be Prevented?

Yes! You can prevent PFPS by:

• Warming up and cooling down properly

• Strengthening leg and hip muscles

• Cross-training to avoid overuse

• Wearing appropriate footwear

• Gradually increasing workout intensity

Conclusion:

Patellofemoral Pain Syndrome (PFPS), once regarded as a minor discomfort among active individuals, is now recognized as a significant contributor to chronic knee pain and functional limitations if left unaddressed. However, both evidence and clinical practice highlight that early recognition and individualized management—especially through physiotherapy—can lead to substantial improvements in symptoms and joint mechanics.

With proper care, including activity modification, muscle strengthening, and movement correction, individuals with PFPS can continue their daily and athletic activities without exacerbating the condition. These interventions play a vital role in restoring knee function, preventing recurrence, and reducing the likelihood of long-term joint stress.

By understanding PFPS and partnering with healthcare providers, individuals can make proactive choices, take control of their knee health, and maintain an active, pain-free lifestyle over the long term.

References:

1. Steffens, D., Hodges, P., Vicenzino, B., Namdari, S., & Rolfe, P. (2022). Six treatments have positive effects at 3 months for people with patellofemoral pain: A systematic review with meta-analysis. Journal of Orthopaedic & Sports Physical Therapy, 52(11), 750–768.

2. Higgins, J., Thompson, A., & Smith, R. (2025). The efficacy of hip and knee muscle strengthening versus knee muscle strengthening alone in managing patellofemoral pain syndrome: A systematic review and meta-analysis. Journal of Orthopaedic & Sports Physical Therapy. Advance online publication.

3. Zhang, Z., Zheng, B., Yang, Y., Sun, Y., Liu, X., & Wang, Q. (2025). Effects of lower limb strengthening training on lower limb biomechanical characteristics and knee pain in patients with patellofemoral pain: A systematic review and meta-analysis. European Journal of Medical Research, 30(1), 90.

4. Fuhad, A., Zahari, Z., & Justine, M. (2023). Current physiotherapy approaches for patellofemoral pain syndrome: A systematic review. Environment-Behaviour Proceedings Journal, 8(24), Article 4673.

5. Liu, Y., Li, H., Zhang, D., Zhao, T., Liu, Z., Chen, J., Gong, M., Pan, J., & Wang, Y. (2024). Core training for pain management and functional improvement in patients with patellofemoral pain syndrome: A systematic review and meta-analysis. American Journal of Physical Medicine & Rehabilitation, 103(12), 1094–1103.