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Patellofemoral Joint

From WikiSM

Description

  • Patellofemoral joint (PFJ) arthritis. A. Skyline X-Ray showing PFJ osteoarthritis. B. Skyline X-ray after PFJ replacement. C. Lateral X-ray showing PFJ osteoarthritis. D. Postoperative lateral X-ray after PFJ arthroplasty. E. Anteroposterior X-ray after PFJ arthroplasty[1]
    Patellofemoral joint (PFJ) arthritis. A. Skyline X-Ray showing PFJ osteoarthritis. B. Skyline X-ray after PFJ replacement. C. Lateral X-ray showing PFJ osteoarthritis. D. Postoperative lateral X-ray after PFJ arthroplasty. E. Anteroposterior X-ray after PFJ arthroplasty[1]
  • Six degrees of freedom movement of the patella relative to the femorotibial joint[2]
    Six degrees of freedom movement of the patella relative to the femorotibial joint[2]
  • Schematic indices of patellofemoral joint anatomy[3]
    Schematic indices of patellofemoral joint anatomy[3]
  • Axial radiograph illustrating medial patellofemoral joint arthritis
    Axial radiograph illustrating medial patellofemoral joint arthritis
  • Patellofemoral joint anatomy
    Patellofemoral joint anatomy
  • Patellofemoral joint anatomy
    Patellofemoral joint anatomy
The patellofemoral joint is marked in green[4]
Normal sunrise view of the patella and patellofemoral joint
Merchant view demonstrating key anatomical angles and measurements. Patellar tilt angle (PTA) (a): the angle formed between a line connecting anterior points of medial/lateral facets of the patella and a line tangent to the femoral condyles. Normally less than 5° laterally. Increased patellar tilt angle can lead to patellar maltracking. Congruence angle (CA) (b): angle between a line drawn perpendicularly to the deepest point of the trochlear groove and a line from the same point to the apex of the patella. Normally, it is −6° (range −6° to +16°). Positive CA suggests lateral displacement of the patella, which may be associated with patellar subluxation or lateral tracking issues. Tibial tubercle-trochlear groove (TT-TG) distance (c): the horizontal distance between the lowest point of the trochlear groove and a line connecting the highest points of the medial and lateral femoral condyles, best measured on CT. Generally, a TT-TG distance under 15-20 mm is considered normal. A measurement exceeding this range suggests a lateralized tibial tubercle, which can affect patellar tracking. Lateral patellar curvature angle (LPCA) (d): the angle is formed between a line along the lateral facet of the patella and a perpendicular line to the patella's axis. While normal values vary, a sharper lateral patellar curvature angle indicates a steeper lateral facet, increasing contact pressures on the lateral patellofemoral joint and contributing to lateral patellar tilt or maltracking.[5]

Name

  • Patellofemoral Joint
  • Kneecap Joint
  • Patellar joint
  • Patellar–femoral articulation
  • Femoro–patellar joint
  • Patellofemoral articulation
  • Kneecap joint (informal)
  • Anterior knee joint compartment (anatomical description)
  • Patellofemoral compartment of the knee

General

  • Biomechanically complex
  • Synovial joint between the condyles of the Femur, articular surface of Patella
  • Contiguous and part of the the Knee Joint
  • Posterior patella: medial, lateral and odd facets articulate; lateral is largest and steepest
  • Femur: medial and lateral condyles articulate
  • Articular surface covered with Articular Cartilage
  • Joint capsule is contiguous with the knee joint

Static stabilizers

Dynamic stabilizers

Actions

  • Knee extension
    • Patellar slides along femoral condyles
    • Increases lever arm of the extensor mechanism
  • Transmits tensile forces generated by the quadriceps to the patellar tendon

Vascular Supply

  • Branches of the Popliteal Artery including
    • Superior, inferior medial, lateral geniculate arteries
  • Branches of the Femoral Artery including
    • Descending geniculate branches

Innervation

Clinical Significance

Atraumatic

Traumatic

See Also

References

  1. ↑ Ahmad, Sufian S., et al. "Arthroplasty–current strategies for the management of knee osteoarthritis." Swiss medical weekly 145.0708 (2015): w14096-w14096.
  2. ↑ Xue, Zhe, et al. "Development of an innovative measurement method for patellar tracking disorder." Aging (Albany NY) 13.1 (2020): 516.
  3. ↑ Leiprecht, J., et al. "Weight-bearing MRI with a knee flexion angle of 20: a study on additional MRI investigation modalities to support a more accurate understanding of patellofemoral instability." BMC Musculoskeletal Disorders 22.1 (2021): 902.<
  4. ↑ Image courtesy of kenhub.com
  5. ↑ Masroori, Zahra, et al. "Patellar Non-Traumatic Pathologies: A Pictorial Review of Radiologic Findings." Diagnostics 14.24 (2024): 2828.
Created by:
John Kiel on 9 February 2021 00:19:04
Authors:
Last edited:
11 October 2025 02:23:51
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