- 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;
- may arise from mid patellar vessels penetrating 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
- references:
- Quantitative and qualitative assessment of bone perfusion and arterial contributions in a patellar fracture model using gadolinium-enhanced magnetic resonance imaging: a cadaveric study.
- Vascular anatomy of the patella: implications for total knee arthroplasty surgical approaches.
- Safe zone for the descending genicular artery in the midvastus approach to the knee.