What could be causing knee pain on the top and sides of my patella that worsens with walking or climbing stairs, is not swollen but red?

Patellofemoral Pain Syndrome (PFPS)

Your symptoms—pain on the top and sides of the patella worsening with walking and stair climbing without swelling—are classic for patellofemoral pain syndrome, and you should start with knee-targeted exercise therapy focusing on eccentric quadriceps strengthening as first-line treatment. 1, 2

Clinical Diagnosis

Your presentation is textbook PFPS, characterized by:

• Peripatellar pain (around the kneecap) that worsens with loading activities 1, 3
• Stair climbing pain is the hallmark symptom, occurring when the patellofemoral joint experiences maximum compressive forces 1, 4
• Absence of swelling or redness distinguishes this from inflammatory conditions like patellar tendinopathy 1, 3
• Pain typically occurs behind or around the patella during activities involving knee flexion under load 2, 4

The redness you mention is unusual for PFPS and warrants consideration of alternative diagnoses, though it may represent superficial skin irritation rather than true pathology 3.

Initial Imaging Approach

Start with plain radiographs (anteroposterior and lateral views) of the knee before any advanced imaging. 1

• Radiographs should include frontal projection, tangential patellar view, and lateral view to exclude fractures, osteoarthritis, or loose bodies 1, 5
• Approximately 20% of patients inappropriately receive MRI without recent radiographs—avoid this error 1, 6
• MRI without IV contrast is indicated only if radiographs are normal but pain persists beyond 6 weeks of conservative treatment 1

First-Line Treatment: Exercise Therapy

Begin individualized knee-targeted exercise therapy immediately, with or without hip strengthening depending on your specific impairments. 1, 2

Exercise Protocol Details

• Eccentric quadriceps exercises are the cornerstone of treatment and show consistent benefit for reducing pain and improving function 1, 2
• Exercise therapy reduces pain during activity by approximately 1.5 points on a 0-10 scale and improves function by 12 points on the Anterior Knee Pain Score—both clinically meaningful improvements 2
• Hip plus knee exercises may be superior to knee exercises alone, reducing pain by an additional 2.2 points compared to knee-only programs 2
• Treatment should be guided by your symptom severity and irritability—if you have poor tolerance to loaded knee flexion, start with hip-focused exercises before progressing to direct knee loading 1

Specific Exercise Considerations

• Closed kinetic chain exercises (like squats) versus open kinetic chain exercises (like leg extensions) show variable results, so choose based on which you tolerate better 2
• A decline squat test often reproduces patellar pain and can guide exercise prescription 1
• Physical therapy is more effective than NSAIDs or knee braces for long-term outcomes 3

Supporting Interventions

Add patellar taping if your pain severity limits rehabilitation participation or quality of life. 1

• Taping should be considered when elevated symptom severity, high irritability, or fear of movement hinders exercise adherence 1
• Prefabricated foot orthoses should be prescribed only if you respond favorably to treatment direction tests (symptom improvement during functional tasks with orthoses in place) 1
• Deep transverse friction massage may reduce pain but is secondary to exercise therapy 1

What NOT to Do

Avoid corticosteroid injections for PFPS—they are indicated for patellar tendinopathy, not patellofemoral pain syndrome. 1

• NSAIDs have limited evidence for routine use in PFPS 3
• Knee braces lack strong supporting evidence 3
• Surgery should only be considered after failure of comprehensive rehabilitation lasting at least 3-4 months 1, 3

Red Flags Requiring Further Evaluation

If radiographs are normal but pain persists beyond 6 weeks of exercise therapy, obtain MRI without IV contrast to exclude:

• Patellar tendinopathy (pain at inferior pole of patella, not around it) 1, 7
• Osteochondritis dissecans 1, 8
• Subchondral insufficiency fractures (may show normal initial radiographs) 1, 6
• Meniscal pathology or cartilage lesions 1

Consider hip radiographs if knee imaging is unremarkable, as hip pathology commonly refers pain to the knee. 1, 6, 5

Expected Timeline

• Minimum 6 weeks of exercise therapy before reassessing treatment approach 1
• Most patients show improvement within 3-4 months of consistent exercise 1
• Long-term recovery (12 months) shows 88 additional patients per 1000 recover compared to no treatment 2

Critical Pitfall to Avoid

The single most important error is assuming normal radiographs exclude significant pathology—patients with PFPS can have normal X-rays but still require structured treatment. 1, 8 However, your clinical presentation is so typical for PFPS that if radiographs are normal, you should proceed directly to exercise therapy rather than rushing to MRI 1, 2.