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Dog · Skeletal system

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Model: 3D Dog Bone Project, Massey University (School of Veterinary Science and Institute of Natural and Mathematical Sciences), nzfauna on Sketchfab, CC BY-SA 4.0

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Femur

Os femoris

Long bone of the thigh. Articulates proximally with the acetabulum of the hip bone and distally with the tibia and the patella.

Laterality:: Paired (left and right)

Draft, not yet reviewed by a veterinarian. Content may contain errors. It is published so the community can review it.

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Overview

The femur is the longest and strongest bone of the dog. It forms the skeleton of the thigh and transmits the weight of the trunk to the leg through two joints: the coxofemoral joint (hip) at its proximal end and the stifle joint (articulatio genus) at its distal end.

Proximal end

Head (caput ossis femoris): spherical articular surface that sits in the acetabulum. It carries the fovea capitis, a small depression where the ligament of the femoral head attaches.
Neck (collum ossis femoris): joins the head to the shaft. Its angle to the shaft (angle of inclination, about 145° in the dog) is one of the measurements used when assessing hip dysplasia.
Greater trochanter (trochanter major): large lateral projection where the gluteal muscles insert. It is palpable in the live animal and is a landmark for hip joint injection.
Lesser trochanter (trochanter minor): smaller medial projection where the iliopsoas muscle inserts.
Trochanteric fossa (fossa trochanterica): depression between the neck and the greater trochanter.

Shaft

The diaphysis is cylindrical and slightly convex cranially. On its caudal surface lies the facies aspera, with medial and lateral lips where the adductor muscles insert.

Distal end

Trochlea (trochlea ossis femoris): cranial groove in which the patella glides. Its depth matters in patellar luxation: a shallow trochlea lets the patella slip out.
Medial and lateral condyles (condylus medialis et lateralis): caudal articular surfaces that contact the menisci and the tibia.
Intercondylar fossa: between the condyles; houses the cruciate ligaments.
Fabellae: two small sesamoid bones in the tendons of origin of the gastrocnemius, caudal to the condyles. They appear on lateral stifle radiographs and must not be mistaken for fragments.

Clinical relevance

Several of the most frequent orthopaedic diseases of the dog involve this bone: hip dysplasia (head and neck), Legg-Calvé-Perthes disease (necrosis of the head in small breeds), patellar luxation (trochlea), diaphyseal fractures after trauma, and osteosarcoma in the distal femur of large breeds.