What is the difference in location between tricompartmental and patellofemoral conditions in the knee?

Anatomical Differences Between Tricompartmental and Patellofemoral Conditions in the Knee

Tricompartmental conditions affect all three compartments of the knee (medial tibiofemoral, lateral tibiofemoral, and patellofemoral), while patellofemoral conditions affect only the articulation between the patella and femoral trochlea.

Anatomical Compartments of the Knee

The knee joint consists of three distinct compartments:

1. Medial Tibiofemoral Compartment:

   • Located on the inner (medial) side of the knee
   • Articulation between the medial femoral condyle and medial tibial plateau
   • Bears approximately 60% of weight-bearing forces during normal gait

2. Lateral Tibiofemoral Compartment:

   • Located on the outer (lateral) side of the knee
   • Articulation between the lateral femoral condyle and lateral tibial plateau
   • Bears approximately 40% of weight-bearing forces during normal gait

3. Patellofemoral Compartment:

   • Located at the front of the knee
   • Articulation between the posterior surface of the patella and the femoral trochlea
   • Experiences significant compressive forces during activities requiring knee flexion

Patellofemoral Conditions

Patellofemoral conditions specifically involve:

• The articulation between the patella (kneecap) and the trochlear groove of the femur 1
• Primarily affects the anterior portion of the knee
• Common conditions include:
  • Patellofemoral osteoarthritis
  • Patellofemoral pain syndrome
  • Patellar instability or malalignment
  • Chondromalacia patellae

Patellofemoral conditions often present with:

• Anterior knee pain, especially when climbing stairs or sitting for prolonged periods
• Pain with activities that increase patellofemoral compressive forces
• Possible crepitus with knee flexion and extension

Tricompartmental Conditions

Tricompartmental conditions involve all three compartments of the knee:

• Medial tibiofemoral compartment
• Lateral tibiofemoral compartment
• Patellofemoral compartment 2

The most common tricompartmental condition is advanced osteoarthritis affecting all three compartments, often referred to as "tricompartmental osteoarthritis."

Tricompartmental conditions typically present with:

• More diffuse knee pain
• Pain with weight-bearing activities
• Limited range of motion
• Joint effusion
• Multiple areas of tenderness on examination

Clinical Implications of Compartmental Involvement

The distinction between patellofemoral and tricompartmental conditions has important clinical implications:

1. Diagnostic Imaging:

   • Patellofemoral conditions may require specific radiographic views (e.g., axial/skyline views) to properly visualize the patellofemoral joint 1
   • Tricompartmental assessment requires standard AP, lateral, and axial views to evaluate all compartments

2. Treatment Approaches:

   • Isolated patellofemoral conditions may respond to targeted interventions like physical therapy focusing on quadriceps strengthening or patellofemoral bracing 2
   • Tricompartmental conditions often require more comprehensive management approaches

3. Surgical Management:

   • Patellofemoral conditions may be amenable to compartment-specific interventions like patellofemoral arthroplasty
   • Tricompartmental disease typically requires total knee arthroplasty when surgical intervention is indicated 2, 3

Radiographic Assessment

Different imaging modalities highlight the anatomical differences:

• Radiographs: Standard radiographs can show joint space narrowing in the tibiofemoral compartments, while skyline/axial views are needed to assess the patellofemoral compartment 1

• MRI: Provides detailed assessment of all three compartments, including cartilage integrity, bone marrow lesions, and synovitis 1

  • Patellofemoral cartilage loss is associated with chronic knee pain 1
  • Bone marrow lesions in the patellofemoral region correlate with active knee pain 1

Biomechanical Considerations

The biomechanical forces differ between compartments:

• Patellofemoral joint experiences primarily compressive forces that increase with knee flexion 4
• Tibiofemoral compartments experience both compressive and shear forces during weight-bearing activities
• Tricompartmental conditions affect the overall biomechanics of the knee, while patellofemoral conditions may primarily affect anterior knee function 4

Understanding the anatomical distinction between patellofemoral and tricompartmental conditions is essential for accurate diagnosis, appropriate treatment selection, and optimal patient outcomes.