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Topic

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Femur

The femur is the longest, heaviest, and strongest bone in the human body. It extends from the hip to the knee, articulating proximally with the acetabulum of the pelvis and distally with the tibia and patella. The femur is essential for weight-bearing, locomotion, and maintaining upright posture. Its anatomy includes the head, neck, greater and lesser trochanters, shaft, and distal condyles. Clinically, the femur is one of the most commonly injured bones in high-energy trauma and is a frequent site for tumors, infections, and orthopedic interventions.

Synonyms

  • Thigh bone

  • Os femoris

  • Long bone of the thigh

Structure and Relations

  • Proximal femur:

    • Head: Spherical, articulates with acetabulum, covered by articular cartilage except for fovea capitis

    • Neck: Connects head to shaft; common site for fractures

    • Greater trochanter: Large lateral projection for gluteal muscle attachments

    • Lesser trochanter: Medial projection for iliopsoas insertion

  • Shaft: Long, cylindrical, slightly anteriorly convex, with linea aspera on posterior surface for muscular attachments

  • Distal femur:

    • Medial and lateral condyles: Articulate with tibia and patella

    • Intercondylar fossa: Between condyles, attachment for cruciate ligaments

  • Relations:

    • Surrounded by quadriceps, hamstrings, adductors, and gluteal muscles

    • Major neurovascular bundles (femoral, sciatic, popliteal) course alongside

Nerve Supply

  • No direct innervation to bone tissue

  • Periosteum supplied by sensory branches of femoral, obturator, and sciatic nerves

Arterial Supply

  • Femoral head and neck: Supplied by medial and lateral circumflex femoral arteries, retinacular branches, and artery of ligamentum teres (minor)

  • Shaft: Nutrient artery from profunda femoris artery, periosteal branches from femoral and profunda femoris arteries

  • Distal femur: Genicular arteries from popliteal artery

Venous Drainage

  • Nutrient vein accompanies nutrient artery → profunda femoris vein → femoral vein

  • Periosteal and metaphyseal veins drain into femoral and popliteal systems

Function

  • Supports body weight and transmits forces between pelvis and lower limb

  • Provides levers for locomotion and muscular attachment sites

  • Forms major articulations: hip (acetabulofemoral joint) and knee (tibiofemoral and patellofemoral joints)

Clinical Significance

  • Fractures:

    • Neck fractures: common in elderly, risk of avascular necrosis

    • Shaft fractures: high-energy trauma

    • Distal fractures: intra-articular involvement, complicating knee function

  • Bone tumors: Osteosarcoma, Ewing sarcoma, chondrosarcoma

  • Metastases: Common site for secondary bone tumors

  • Infections: Osteomyelitis

  • Orthopedic relevance: Target for hip replacement, intramedullary nailing, arthroplasty, and fixation procedures

MRI Appearance

T1-weighted images:

  • Cortex: dark (low signal)

  • Marrow: bright to intermediate signal depending on fat content

  • Pathology: fracture lines (dark), tumor infiltration (low signal replacing fat)

T2-weighted images:

  • Cortex: dark (signal void)

  • Marrow: bright to intermediate signal depending on fat content

  • Pathology: edema, infection, or tumor appear as hyperintense areas

STIR (Short Tau Inversion Recovery):

  • Cortex: dark

  • Normal marrow: suppressed to low signal

  • Pathology (marrow edema, abscess, tumor, fracture): bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Cortex: no enhancement

  • Normal marrow: mild uniform enhancement

  • Pathology: heterogeneous, nodular, or rim enhancement (e.g., tumor, infection, abscess)

CT Appearance

Non-Contrast CT:

  • Cortex: very dense (bright white)

  • Medullary cavity: lower attenuation than cortex

  • Fractures: cortical breaks or lucent lines

  • Tumors: lytic (low density) or sclerotic (high density) lesions

Post-Contrast CT:

  • Cortex: does not enhance

  • Marrow: mild uniform enhancement

  • Tumors or infections: heterogeneous or irregular enhancement

  • Abscess/necrosis: rim enhancement with central low attenuation

MRI image

Femor MRI CORONAL anatomy image-img-00000-00000

MRI image

Femor MRI SAG anatomy image-img-00000-00000

CT image

Femor CT IMAGE

CT VRT 3D image

Femor CT 3d IMAGE