Differentiating Patellofemoral and Tibiofemoral Knee Pain

Knee pain is a common source of discomfort, affecting about 25 % of adults¹. Anterior knee pain frequently occurs in young athletes, with a prevalence of roughly 40 %². The overall rate of knee pain has increased by nearly 65 % over the last two decades¹.

The knee consists of two main joints — the tibiofemoral joint and the patellofemoral joint — and pain may arise from a variety of intra- or extra-articular structures.

Accurate differentiation between patellofemoral and tibiofemoral pain relies on a thorough history and a structured clinical examination.

Relevant Anatomy

Tibiofemoral joint:The articulation between the femur and tibia. It includes:

• Intra-articular structures: menisci, anterior cruciate ligament (ACL), posterior cruciate ligament (PCL)

• Extra-articular stabilizers: medial collateral ligament (MCL) and lateral collateral ligament (LCL)

Patellofemoral joint: Where the patella, a triangular sesamoid bone, articulates with the femoral trochlea. The patella functions as a pulley, improving the moment arm of the quadriceps. Beneath it lies the infrapatellar fat pad, which may itself become a pain generator.

Etiology and Pathophysiology

Patellofemoral sources

• Patellofemoral pain syndrome (PFPS)

• Patellar tendinopathy

• Patellar dislocation or instability

• Fat-pad impingement

• Patellofemoral osteoarthritis

Tibiofemoral sources

• Ligament injuries (ACL, PCL, MCL, LCL)

• Meniscal lesions

• Chondral damage

• Tibiofemoral osteoarthritis

Clinical Differentiation

Age and Demographics

The likelihood of osteoarthritis increases with age³. Even asymptomatic individuals may show MRI changes⁴:

• 4–14 % of adults under 40 years

• 19–43 % of adults over 40 years

Patellofemoral pain is more frequent in younger, active populations, while tibiofemoral degenerative pain predominates after midlife.

Pain Location

Pain location is one of the strongest diagnostic clues:

Patellofemoral pain

• Diffuse ache around or behind the patella

• Pain when climbing stairs, squatting, or sitting long periods (“movie sign”)

• Pain at the inferior pole → possible fat-pad impingement or tendinopathy

Tibiofemoral pain

• Localized along the joint line

• Medial pain aggravated by valgus stress → suspect MCL injury

• Lateral pain with varus stress → possible LCL or lateral meniscus pathology

Onset and Mechanism

Gradual onset

• Suggests overuse syndromes such as PFPS, tendinopathy, or early osteoarthritis

• In adolescents, may indicate Osgood–Schlatter or Sinding–Larsen–Johansson

Acute trauma

• Commonly involves ligament, meniscus, or cartilage injury

• Rotation or forced extension → ACL

• Forced flexion → PCL

• Twisting with fixed foot → meniscal lesion

Associated Findings

Finding	Patellofemoral pattern	Tibiofemoral pattern
Swelling	Mild or localized around patella	Often joint effusion; diffuse
Audible pop	Occasionally with patellar dislocation	Common with ACL injury
Clicking/locking	Usually pseudo-locking due to pain or maltracking	True locking → meniscal tear
Instability	“Pseudo-giving-way” from quadriceps inhibition	True instability → ligament rupture
Pain behaviour	Worse during activity, sometimes better after rest	OA: stiffness after rest, improves with gentle motion

Examination

Observation

Assess in both standing and supine:

• Alignment (genu varum/valgum)

• Patellar height and tilt

• Swelling, discoloration, deformity

• Quadriceps atrophy

Range of Motion

Observe:

• Active and passive flexion/extension

• End-feel and movement quality

• Fear of movement or guarding

Palpation

• Patellofemoral pain → tenderness around patellar borders or retinaculum

• Tibiofemoral pain → tenderness along medial/lateral joint line

• Note warmth or effusion (suggesting inflammation or OA)

Special Tests

Patellofemoral

• Clarke’s test (patellar compression)

• Patellar glide and tilt assessment

• Functional squat test

Tibiofemoral

• Lachman and Pivot-Shift (ACL)

• Posterior drawer (PCL)

• Valgus/varus stress (MCL/LCL)

• McMurray or Thessaly (meniscus)

Interpret all test results in combination with history and observation rather than in isolation¹⁵.

Imaging

• X-ray: structural degeneration or fracture

• MRI: gold standard for meniscus, ligament, and cartilage lesions

• Ultrasound: evaluation of patellar tendon and fat pad

Imaging should support, not replace, clinical reasoning.

Management Principles

Patellofemoral pain

• Correct biomechanical issues (hip control, Q-angle, patellar tracking)

• Strengthen quadriceps and hip abductors

• Gradual load progression and taping if appropriate

Tibiofemoral pain

• Restore stability, mobility, and strength

• Address deficits from ligament or meniscal injury

• For osteoarthritis: weight management, low-impact exercise, education

General conservative care advantages

• Avoids surgery and complications

• Encourages long-term function through exerciseLimitations

• Symptoms may persist; requires adherence and time

Rehabilitation and Return to Activity

Rehabilitation should be individualized and progressive:

1. Acute phase: pain control, swelling reduction, gentle ROM

2. Subacute phase: targeted strengthening, neuromuscular training

3. Functional phase: closed-chain and sport-specific drills

Progression criteria

• Pain-free ROM

• ≥ 90 % strength compared with contralateral side

• No swelling or instability

Return to sport should be gradual and criteria-based.

Prevention

• Maintain strong quadriceps and hip stabilizers

• Focus on alignment and landing control

• Warm-up thoroughly and increase load progressively

• Address early pain to avoid chronic pathology

Clinical Summary

Patellofemoral pain tends to be diffuse, anterior, and aggravated by loading activities involving knee flexion.Tibiofemoral pain is typically localized, often linked to structural pathology such as ligament, meniscal, or chondral injury.Accurate differentiation enables targeted rehabilitation, better prognosis, and prevention of chronic dysfunction.

References

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