Structure
The distal femur has two condyles joined in front by the patellar surface and separated behind by the intercondylar fossa (notch). Above each condyle is a roughened epicondyle for the collateral ligaments.
| Feature | Medial femoral condyle | Lateral femoral condyle |
|---|---|---|
| Shape | Longer, more curved articular surface; projects further down | Broader, straighter; projects further forward |
| Patellar groove | Lower medial lip | Higher, more prominent lateral lip |
| Epicondyle | Medial collateral ligament; adductor tubercle above it | Lateral collateral ligament; popliteus groove below it |
| Notch wall | Posterior cruciate ligament on its lateral surface | Anterior cruciate ligament on its medial surface |
The femoral shaft slopes inwards from hip to knee, so the medial condyle has to project further down for the two condyles to sit level on the horizontal tibial plateau.
Patellar surface
The patellar surface (trochlea) is the smooth saddle-shaped groove on the front of the distal femur. Its upper parts are the anterior, superior aspects of the two condyles, where the patella sits in extension. The higher lateral lip is the main bony restraint against lateral dislocation of the patella.
Intercondylar fossa and popliteal surface
The intercondylar fossa is the deep notch between the condyles at the back, lined on its walls by the cruciate attachments. Above it, the flat triangular popliteal surface forms the floor of the popliteal fossa.
Attachments
Muscles and ligaments cluster around the epicondyles and the back of the condyles.
- Adductor tubercle: the tendon of the hamstring part of adductor magnus. The distal femoral growth plate lies at the level of this tubercle.
- Medial head of gastrocnemius: the popliteal surface just above the medial condyle.
- Lateral head of gastrocnemius: the posterolateral surface of the lateral condyle.
- Plantaris: the lower lateral supracondylar line, above the lateral head.
- Popliteus: a pit in front of the groove on the lateral condyle, below and deep to the lateral collateral ligament.
- Articularis genus: the front of the shaft above the patellar surface.
The fibrous capsule attaches close to the articular margins, but in front it is replaced by the suprapatellar bursa, which extends well above the patellar surface.
Relations: the medial tibial condyle
The medial tibial condyle is the partner of the medial femoral condyle in the medial tibiofemoral compartment. Its upper surface, the medial tibial plateau, is oval, slightly concave and larger than the lateral plateau, and it carries the C-shaped medial meniscus. A horizontal groove on its posteromedial surface takes the main insertion of semimembranosus, and the deep fibres of the medial collateral ligament attach along its margin.
Behind the distal femur, the popliteal artery lies directly on the popliteal surface and the back of the capsule, separated from bone only by a thin layer of fat. That close contact explains the arterial injuries in supracondylar fractures and knee dislocations.
Clinical relevance
The distal femur carries the whole weight of the body across the knee and fails in characteristic patterns.
- Supracondylar fracture: gastrocnemius pulls the distal fragment backwards into flexion, where it can injure the popliteal artery.
- Medial compartment osteoarthritis: the medial side carries more load in normal alignment and wears first, producing a varus knee.
- Osteochondritis dissecans: classically affects the lateral part of the medial femoral condyle in adolescents.
- Trochlear dysplasia: a shallow groove with a low lateral lip predisposes to recurrent patellar dislocation.
- Bone bruising in ACL rupture: MRI shows contusions on the lateral femoral condyle and the back of the lateral tibial plateau where they impact as the tibia shifts forwards.
- Tibial plateau fracture: the lateral plateau fractures more often, from a valgus force; medial plateau fractures imply higher energy. The Schatzker classification grades them.
On the specimen
The station shows the bony knee with the soft tissues removed, so the markers test bony orientation. Side the femur first: the patellar surface faces forwards, the notch faces backwards, and the condyle with the higher lip of the patellar groove is lateral.
The markers on the 'superior aspect' of each condyle sit on the upper, anterior parts where the articular surface climbs into the patellar groove, and the lateral one stands higher. The whole medial condyle is recognised by its longer, more curved outline and the adductor tubercle above it; the lateral condyle by its broader face and the popliteus groove on its outer side. On the tibia, the medial condyle is the larger, more concave plateau.