Topics

Topic

design image
Hip joint

The hip joint is a large, stable ball-and-socket synovial joint formed between the head of the femur and the acetabulum of the pelvis. It allows a wide range of motion while providing stability required for weight-bearing and locomotion. Stability is reinforced by a deep acetabular socket, fibrocartilaginous labrum, strong ligaments, and surrounding muscles.

Movements include flexion, extension, abduction, adduction, internal rotation, external rotation, and circumduction, making the hip joint vital for posture, gait, and balance.

Articulating Surfaces

  • Femoral head: Nearly spherical, covered with hyaline cartilage (except fovea capitis)

  • Acetabulum: Cup-shaped socket of pelvis, lined with cartilage and deepened by acetabular labrum

  • Acetabular labrum: Fibrocartilaginous rim that increases depth and stability

Ligaments

  • Capsular ligaments:

    • Iliofemoral ligament: Strongest ligament, prevents hyperextension

    • Pubofemoral ligament: Limits excessive abduction and extension

    • Ischiofemoral ligament: Reinforces posterior capsule, limits internal rotation

  • Intracapsular ligament:

    • Ligamentum teres (ligament of head of femur): Carries branch of obturator artery to femoral head

  • Acetabular labrum and transverse acetabular ligament: Deepen and stabilize the socket

Tendon Attachments

  • Anterior hip: Iliopsoas tendon passing anteriorly, inserting on lesser trochanter

  • Posterior hip: Tendons of short external rotators (piriformis, obturator internus, gemelli, quadratus femoris)

  • Lateral hip: Gluteus medius, gluteus minimus attaching to greater trochanter

  • Anterior superior pelvis: Sartorius and rectus femoris originate near the anterior inferior iliac spine

Muscles Acting on Hip

  • Flexors (anterior): Iliopsoas, rectus femoris, sartorius

  • Extensors (posterior): Gluteus maximus, hamstrings (biceps femoris long head, semitendinosus, semimembranosus)

  • Abductors: Gluteus medius, gluteus minimus, tensor fasciae latae

  • Adductors: Adductor longus, adductor brevis, adductor magnus, gracilis, pectineus

  • Rotators: External (piriformis, obturator internus, gemelli, quadratus femoris); Internal (anterior fibers of gluteus medius/minimus, tensor fasciae latae)

Nerve Supply

  • Femoral nerve: Anterior capsule

  • Obturator nerve: Inferomedial capsule

  • Sciatic nerve branches: Posterior capsule

  • Superior gluteal nerve: Superolateral capsule

Arterial Supply

  • Medial circumflex femoral artery: Principal supply to femoral head and neck

  • Lateral circumflex femoral artery: Supplies anterior capsule and proximal femur

  • Obturator artery (acetabular branch): Via ligamentum teres to femoral head

  • Superior and inferior gluteal arteries: Posterior contributions

Venous Drainage

  • Femoral vein receives venous return via circumflex femoral veins

  • Obturator and gluteal veins contribute to deep venous plexus

Function

  • Mobility: Multiaxial joint allowing flexion, extension, abduction, adduction, rotation, and circumduction

  • Stability: Deep socket, labrum, strong ligaments, and surrounding muscles provide stability under heavy load

  • Shock absorption: Articular cartilage distributes forces during walking and running

  • Weight-bearing: Transfers upper body weight to lower limbs

Clinical Significance

  • Dislocation: Traumatic (posterior most common) or congenital hip dysplasia

  • Fractures: Femoral neck fractures jeopardize blood supply, risk avascular necrosis

  • Degeneration: Osteoarthritis common in elderly or post-trauma

  • Labral tears: Cause pain, clicking, and restricted motion

  • Surgical relevance: Total hip arthroplasty and hip arthroscopy frequent interventions

MRI Appearance

  • T1-weighted images:

    • Normal: femoral head and acetabulum cortical margins dark, marrow intermediate signal

    • Cartilage: intermediate to dark layer covering surfaces

    • Labrum: low signal intensity triangle at acetabular rim

    • Pathology: femoral head avascular necrosis shows low signal subchondral crescent

  • T2-weighted images:

    • Joint fluid: bright hyperintense signal outlining cartilage and labrum

    • Cartilage lesions: focal hyperintense defects

    • Labral tears: high-signal cleft within dark labrum

    • Subchondral cysts: hyperintense rounded lesions in acetabulum or femoral head

  • STIR:

    • Suppresses fat, highlights bone marrow edema, effusion, and synovitis

    • AVN: peripheral bright rim, central low signal

  • Proton Density Fat-Saturated (PD FS):

    • Cartilage: intermediate gray signal

    • Labrum: uniformly dark

    • Tears: bright linear signal within labrum or cartilage defect

    • Sensitive for early chondral and labral pathology

  • T1 Fat-Sat Post-Contrast:

    • Synovitis: enhancing synovial tissue

    • Labral tear post-repair: enhancing granulation/scar tissue

    • Infection or tumor: avid enhancement

MRI Arthrogram Appearance

  • Contrast outlines labrum and cartilage surfaces

  • Labral tears: contrast enters cleft or separates labrum from acetabular rim

  • Chondral defects: contrast extends into subchondral bone

  • Improves sensitivity for subtle labral or cartilage injuries

CT Appearance

Non-Contrast CT:

  • Excellent for cortical bone detail: fractures, acetabular dysplasia, osteophytes

  • Cartilage and labrum poorly visualized

  • Subchondral sclerosis and cysts visible

Post-Contrast CT (standard):

  • Capsule and synovial changes enhance

  • Tumors, infections, and inflammatory changes more conspicuous

CT Arthrogram Appearance

  • Contrast delineates acetabular labrum and cartilage

  • Labral tears: contrast fills labral clefts or detaches labrum from rim

  • Cartilage defects: contrast penetrates subchondral bone

  • Superior to standard CT when MRI contraindicated, especially in patients with metal implants

MRI image

Hip Joint axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Hip Joint coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Hip Joint sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT VRT 3D image

Hip joint anatomy 3d ct image

MRI image

Hip Joint axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Hip Joint coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

Hip Joint sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT image

Hip joint anatomy ct axial

CT image

Hip joint anatomy ct coronal image

CT image

Hip joint anatomy ct sagittal