Femur (Thigh Bone)
The major long bone of the hindlimb extending from the hip joint to the stifle (knee) joint.
💬 In Plain English
The femur is the powerful thigh bone of your pet’s hind leg—the longest and strongest bone in the rear limb. At the top, the round femoral head fits securely into the hip socket (acetabulum) to create the ball-and-socket hip joint. At the bottom, the femoral condyles articulate with the tibia to form the stifle (knee) joint, with a smooth groove (trochlea) where the kneecap (patella) glides smoothly up and down. In dogs with hip dysplasia, the ball of the femur becomes flattened or slips out of a shallow socket; in luxating patellas, the bottom femoral groove is too shallow, causing the kneecap to pop out.
🔬 Clinical & Technical Depth
For Vets & TechniciansFormal Clinical Definition
Long bone of the proximal pelvic limb comprising proximal epiphysis (head, neck, greater and lesser trochanters), diaphysis, and distal epiphysis (medial/lateral condyles and trochlear sulcus).
Why Veterinarians Use It
Veterinarians evaluate the femur on hip and stifle radiographs when investigating lameness, hip dysplasia, fractures, or bone cancer (osteosarcoma).
Clinical Context Encountered
Seen on orthopedic surgical consultations for FHO (Femoral Head Ostectomy), Total Hip Replacement (THR), or cruciate surgery.
Clinical Reference Guide (Anatomical Structure)
Anatomical Location
Proximal pelvic limb, positioned obliquely between the os coxae of the pelvis and the proximal tibia/fibula.
Normal Physiological Function
Transmits propulsion force from the pelvic limb musculature to the pelvic girdle during walking, sprinting, and jumping.
🐕 vs 🐈 Species Differences
Cats have straighter, more slender femora compared to the curved, muscular femoral shafts of dogs.
- •Femur fractures are high-energy injuries frequently accompanied by severe internal bleeding or thoracic trauma: immediate shock stabilization and surgical orthopedic fixation are required.
❓ Questions to Ask Your Veterinarian
Take these actionable questions with you to your next clinic visit or appointment:
- 1Is the femoral head seating deeply inside the pelvic hip socket on radiographs?
- 2If severe hip arthritis is present, is a Femoral Head Ostectomy (FHO) or Total Hip Replacement (THR) recommended?
- 3Is the distal femoral trochlear groove deep enough to hold the patella in place?
Academic & Clinical References
- Canine Hip Dysplasia and Proximal Femoral PathologiesOrganization: American College of Veterinary Surgeons (ACVS) • Accessed: 2026-01-10https://www.acvs.org