What causes pain in the front of the leg under and around the knee that worsens with sitting, laying down, or stepping forward?

Anterior Knee Pain Worsened by Prolonged Sitting: Patellar Tendinopathy

This presentation is most consistent with patellar tendinopathy, which characteristically causes anterior knee pain that worsens with prolonged sitting (the "theater sign" or "movie sign"), stair navigation, and stepping forward activities. 1, 2

Clinical Diagnosis

The combination of anterior knee pain worsened by sitting/laying down for extended periods and pain with stepping forward is pathognomonic for patellar tendinopathy:

• Pain location: Specifically at the inferior pole of the patella and anterior knee 1, 2
• Sitting pain: Over 50% of patients with patellofemoral pain (which includes patellar tendinopathy) report problems with prolonged sitting with knee flexion 3
• Activity-related pain: Worsens with stair navigation and stepping forward due to repetitive loading of the patellar tendon 1
• Pain pattern: Sharp or stabbing quality, initially present during activity but may progress to rest pain 1

Physical Examination Findings to Confirm

• Palpation: Well-localized tenderness at the inferior pole of the patella 1, 2
• Resisted leg extension: Pain reproduction with resisted leg extension while leg is fully extended 1, 2
• Decline squat test: Reproduces pain by placing increased load on the patellar tendon 1, 2
• Inspection: Look for quadriceps atrophy (suggests chronicity), swelling, or asymmetry 1

First-Line Treatment Protocol

Eccentric strengthening exercises are the cornerstone of treatment and should be initiated immediately, as they reduce symptoms, increase strength, and promote tendon healing by stimulating collagen production. 2

Phase 1: Acute Management (First 2-4 Weeks)

• Relative rest: Reduce repetitive loading activities (jumping, stairs, prolonged sitting) that reproduce pain, but never completely immobilize as this causes muscular atrophy 2
• Pain control:
  • Topical NSAIDs preferred over oral (eliminates GI hemorrhage risk) for short-term relief 2
  • Cryotherapy through wet towel for 10-minute periods 2
• Deep transverse friction massage: Reduces pain and provides additional benefit 2

Phase 2: Rehabilitation (Weeks 4-12)

• Continue eccentric exercises: This is non-negotiable and must be the primary intervention 2
• Progressive loading: Gradually increase activity as pain permits 2
• Corticosteroid iontophoresis: Effective for pain and function improvement if conservative measures insufficient 2

Critical Pitfalls to Avoid

• Never inject corticosteroids directly into the tendon substance: This inhibits healing, reduces tensile strength, and predisposes to spontaneous rupture 2
• Do not proceed to complete rest: Causes deconditioning and atrophy 2
• Avoid multiple corticosteroid injections: Weakens tendon structure despite short-term symptom relief 2

Expected Outcomes and Surgical Threshold

• 80% of patients recover completely within 3-6 months with appropriate conservative treatment 2
• Surgery is justified only after 3-6 months of well-managed conservative treatment has failed 2
• Surgical options include open or arthroscopic excision of abnormal tendinous tissue and longitudinal tenotomies 2

Alternative Diagnoses to Exclude

While patellar tendinopathy is most likely given the sitting pain and anterior location, briefly consider:

• Nerve root compression: Would present with sharp lancinating pain radiating down leg, worse with sitting but improved supine or standing 1
• Hip arthritis: Lateral hip/thigh aching, not quickly relieved by rest, improved when not bearing weight 1
• Peripheral artery disease: Calf pain with walking that resolves within 10 minutes of rest, not worsened by sitting 1

Red Flags Requiring Imaging

• If multiple tendons symptomatic: Evaluate for underlying rheumatic disease 2
• Recalcitrant pain despite 6-8 weeks conservative management: Consider MRI (78% sensitivity, 86% specificity) or ultrasound (58% sensitivity, 94% specificity) 2
• Suspected traumatic tear: MRI is most accurate for confirming diagnosis 4

Do not obtain imaging initially unless there is concern for acute traumatic tear, as patellar tendinopathy is a clinical diagnosis. 1, 2