Knee Joint Stabilisation Patello-femoral Joint Stability
Patello-femoral Joint Stability
The patello-femoral joint is restrained by a transverse group and a longitudinal group of stabilisers. In the extended knee the patella sits on the femoral sulcus. Medial/lateral stability in extension rests solely on the active and passive tension in the structures around the patella. During flexion, as the patella begins sliding down the femoral condyles it is drawn into the intercondylar notch (at about 20°-30° of flexion). The resulting patello-femoral compression contributes to medial/lateral stability.
The transverse stabilisers of the patella are the medial and lateral patella retinacular which join the vastus medialis and lateralis muscles directly to the patella respectively.
The most important transverse stabiliser of the patella is the medial patello-femoral ligament. This ligament is disrupted in an acute patella dislocation. Depending at the site of damage of the medial patello-femoral ligament it can be acutely repaired to prevent further re-dislocations. This is something that is now being done more frequently in acute patella dislocations (link to acute patella dislocation page).
The longitudinal stabilisers of the patella are the patella tendon inferiorly and the quadriceps tendon superiorly. The longitudinal structures stabilise the patella through the patello-femoral compression that occurs with flexion. This compression is essentially absent in the extended knee leaving the patella relatively unstable in this knee joint position.
Patella tracking within the femoral sulcus is influenced by both the transverse and longitudinal structures along with the configuration of the bony anatomy of the trochlea and patella facets.
