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1Principles

Distal femur with angled blade plate seen from an end-on view

Anatomy of the distal femur

The distal femur has a unique anatomical shape. Seen from an end-on view, the lateral surface has a 10° inclination from the vertical, while the medial surface has a 20–25° slope. A line drawn from the anterior aspect of the lateral femoral condyle to the anterior aspect of the medial femoral condyle (patellofemoral inclination) slopes approximately 10°. These anatomical details are important when inserting screws, or blade plates. In order to avoid joint penetration, these devices should be placed parallel to both the patellofemoral and femorotibial joints planes.

The muscle attachments to the distal femur are responsible for the typical displacement of the distal articular block following a supracondylar fracture, namely shortening with varus and extension deformity. Shortening is due to the pull of the quadriceps and hamstring muscles, while the varus and extension deformity is caused by the unopposed pull of the adductors and gastrocnemius, respectively.

The popliteal vessels, the tibial nerve and the common peroneal nerve lie in close proximity to the posterior aspect of the distal femur. Because of this, vascular injuries occur in about 3% and nerve injuries in about 1% of fractures of the distal femur.