Knee Tendonitis vs. MCL Injury: Key Differences in Pain Location & Presentation

Both cause medial‑sided knee pain, but distinct anatomic structures are involved.

Comparison Table

Feature	Patellar Tendonitis (Jumper's Knee)	MCL Injury
Pain Location	Inferior patellar pole / tibial tuberosity (anterior‑central)	Medial femoral condyle → medial tibial plateau (medial joint line)
Mechanism	Repetitive jumping/loading (eccentric quad contraction)	Valgus stress (direct blow lateral knee or twist planted foot)
Swelling	Localized, often minimal	Often significant, medial aspect
Tenderness	Patellar tendon insertion	MCL femoral/tibial attachment
ROM	Usually full	May limit flexion/extension (esp. Grade II‑III)
Strength	Normal quad strength (pain‑limited)	Possible instability → giving way
Special Tests	Resisted extension pain, single‑leg decline squat	Valgus stress test at 0° & 30° flexion
Imaging	US/MRI: tendon thickening, signal change	MRI: edema, partial/complete tear

Management Overview

• Patellar tendonitis: Load management, eccentric squats, isometrics, shockwave, PRP; surgery rare.
• MCL injury: Grade I‑II: brace, PT, gradual return. Grade III: often non‑op with hinged brace; surgery if multi‑ligament.

Bottom Line

Anterior‑central tendon pain = patellar tendonitis. Medial joint line pain + valgus mechanism = MCL injury. Clinical exam + MRI confirm. See a sports medicine physician or orthopedist.