Knee joint: add part_of for patella and the articulating ends of femur and tibia #3801

Suggested revision and reasons

Summary

knee joint (UBERON:0001485) is modeled as connecting femur, tibia and patella (RO:0002176). The articulating structures have no part_of relationship to it:

• patella (UBERON:0002446): part_of knee, but only "adjacent to" (RO:0002220) knee joint
• medial / lateral condyle of femur (UBERON:0009984, 0009985): no relation to knee joint
• condyle of tibia (UBERON:0009989), tibial plateaux (UBERON:0004098), tibial plateau of tibia (UBERON:1200264): no relation to knee joint

Request

Add part_of knee joint to:

1. patella
2. the articulating regions of the femur (femoral condyles, patellar surface)
3. the articulating regions of the tibia (tibial condyles, tibial plateau)

Option A: assert part_of on the existing condyle and plateau terms. Option B: create articular surface terms (articular surface of femoral condyle, patellar surface of femur, articular surface of tibial plateau, articular surface of patella) as part_of both their bone and the knee joint. We would like curators' preference.

Rationale

• SNOMED CT "Structure of left knee joint" lists femoral condyle, tibial condyles and intercondylar spine as components of the joint.
• Total knee arthroplasty resurfaces the femoral condyles, tibial plateau and usually the patella, which shows they function as part of the joint.
• Radiopaedia defines the tibial plateau as the proximal articular surface of the tibia, so it is already an articular structure.
• The whole femur and tibia should not become part of the joint, only the articulating regions.

Questions for curators

1. Option A or B?
2. Should the relations attach to the subjoints (femorotibial joint, patellofemoral joint) or to the knee joint?
3. tibial plateaux (0004098) and tibial plateau of tibia (1200264) look like duplicates. Should they be merged?
4. How are comparable articulating structures handled at other joints, such as the hip, for consistency?

References

• SNOMED CT, Structure of left knee joint: https://art-decor.org/terminology/snomed/viewConcept/719442003
• Elsevier Anatomy, articular surface of patella: https://www.elsevier.com/resources/anatomy/skeletal-system/appendicular-skeleton/articular-surface-of-patella/20775
• Radiopaedia, tibial plateau: https://images.radiopaedia.org/articles/tibial-plateau

Submitted by: Peter Maye, UConn Health School of Dental Medicine [0000-0003-0098-4399]