- Discussion:
- sesamoid bone w/ in
quadriceps tendon;
- cartilaginous posterior surface is divided by a rounded vertical ridge into a larger, lateral portion for articulation
w/ lateral condyle of femur and smaller medial portion for articulation w/ medial condyle of femur;
- w/ increasing knee flexion, contact pressure moves proximally on patella up to superior pole and onto quadriceps tendon;
- articular surface of patella, varying in thickness from approximately 2 to 5.5 mm, is divided into 7 fascets;
- medial and lateral facets are divided into = 1/3 sections;
- superiorly and inferiorly, with the 7th facet being the most medial portion called the odd facet;
-
Wiberg: 3 shapes based on position of vertical ridge;
- type I:
there are roughly = medial and lateral facets
- type II
most common: medial facet is only 1/2 size of lat. facet;
- type III medial facet is so far medial that the central ridge is barely noticable;
- Blood Supply:
- blood supply to patella originates from as many as 12
nutrient arteries at the inferior pole,
which run upward on the anterior surface of the bone in a series of furrows;
- supply also described as arising from mid patellar vessels penetrating the middle 1/3 of anterior surface &
inferior pole vessels that anastomose at inferior pole of patella;
-
geniculate system feeds these primary vessels;
-
anterior tibial recurrent vessels
- inferior medial genicular
- inferior lateral genicular
