Topics

Topic

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Lesser trochanter

The lesser trochanter is a conical bony projection on the posteromedial aspect of the proximal femur, located at the junction of the femoral neck and shaft. It is smaller than the greater trochanter but serves as a crucial muscular insertion site.

The lesser trochanter provides attachment for the iliopsoas muscle (psoas major and iliacus tendons), the primary hip flexor. This makes it biomechanically important for hip flexion, postural stability, and gait mechanics.

It is clinically relevant because it can be a site of avulsion fractures in adolescents (sports injuries), stress fractures, or pathological involvement such as metastases, osteomyelitis, or primary bone tumors. In adults, an isolated fracture of the lesser trochanter may indicate an underlying pathological lesion.

Attachments

  • Muscle: Insertion of iliopsoas (psoas major and iliacus tendon)

  • Fascia: Iliac fascia may blend at its margins

Relations

  • Lies posteromedial, projecting into the posteromedial thigh

  • Closely related to the medial circumflex femoral artery and vein

  • Forms part of the muscular and vascular compartment boundaries of the hip

Synonyms

  • Trochanter minor

  • Femoral lesser trochanter

Function

  • Acts as the insertion site for iliopsoas muscle, the strongest hip flexor

  • Enables flexion and external rotation of the thigh at the hip joint

  • Contributes to postural stabilization during standing and walking

  • Important in transfer of forces between trunk and lower limb

Nerve Supply (related muscle)

  • Iliopsoas muscle innervated by femoral nerve (L2–L4) and direct branches of lumbar plexus (L1–L3 for psoas major)

Arterial Supply

  • Medial circumflex femoral artery (primary supply)

  • Contributions from lateral circumflex femoral artery and profunda femoris artery

Venous Drainage

  • Via medial and lateral circumflex femoral veins → profunda femoris vein → femoral vein

MRI Appearance

T1-weighted images:

  • Bone cortex: hypointense

  • Bone marrow: intermediate signal intensity

  • Iliopsoas tendon insertion: intermediate to low signal

T2-weighted images:

  • Bone cortex: hypointense

  • Bone marrow: intermediate signal, marrow edema appears hyperintense

  • Iliopsoas tendon pathology (tear, tendinitis): hyperintense near insertion

PD Fat-Saturated (Proton Density FS):

  • Bone cortex: remains dark

  • Marrow edema/avulsion fracture: bright hyperintense signal

  • Excellent for detecting tendon insertion injuries or subtle fractures

STIR:

  • Highlights acute marrow edema, stress fractures, or avulsion injuries as hyperintense regions

  • Useful in adolescent sports injuries and pathological fractures

T1 Post-Gadolinium (with fat saturation):

  • Normal bone cortex: does not enhance

  • Pathology (tumor, infection, inflammation): abnormal heterogeneous enhancement

  • Outlines soft tissue extension from neoplasm or iliopsoas abscess

3D T2-weighted Imaging:

  • Bone cortex: sharply hypointense

  • Provides multiplanar reconstructions to assess trochanter morphology and insertion footprint

  • Helpful in pre-surgical or pre-prosthetic planning

CT Appearance

Non-contrast CT:

  • Bone cortex: hyperdense, sharply defined

  • Marrow: less dense, visible trabecular pattern

  • Best for detecting fractures, cortical irregularities, and sclerosis

CT Post-Contrast:

  • Bone: unchanged

  • Soft tissue enhancement: identifies abscess, tumor infiltration, or vascular lesions near iliopsoas insertion

  • 3D reconstructions aid in fracture planning and orthopedic surgery

CT VRT 3D image

lesser trochanter 3D CT VRT anatomy image

CT image

lesser trochanter ct axial image

MRI image

lesser trochanter MRI axial anatomy image-img-00000-00000

MRI image

Lesser trochanter MRI CORONAL anatomy image-img-00000-00000