The Hip: Anatomy and Clinical Considerations

Overview of the Hip

  • Blood supply to the hip and thigh

  • Development and aging of the hip joint

  • Clinical cases:

    • Gluteal region

    • Neurovasculature

    • Muscles

  • Health related Topics:

    • Hip dislocation vs hip fracture

    • Intramuscular Injection

    • Sciatica and piriformis syndrome

    • Balance and stance

    • Trendelenburg sign

Blood Supply to the Hip and Thigh

  • Key Arteries:

    • Abdominal aorta

    • External iliac artery

    • Superficial circumflex iliac artery

    • Lateral circumflex femoral artery:

    • Transverse branch

    • Descending branch

    • Internal iliac artery

    • Inferior gluteal artery

    • Inferior epigastric artery

    • Superficial epigastric artery

    • Obturator artery

    • Medial circumflex femoral artery:

    • Deep artery of thigh

    • Femoral artery:

    • Posterior retinacular arteries

    • Cruciate anastomosis

    • Perforating arteries

    • Popliteal artery

The Hip Joint

  • Structure:

    • Collateral blood supply from the deep artery of thigh

    • Joint capsule consists of a fibrous layer (iliofemoral ligament) and synovial membrane

    • Medial circumflex femoral artery supplies the head of femur

    • Ligament of head of femur contains acetabular branch (artery to head of femur)

    • Obturator artery also contributes to blood supply

    • Retinacular arteries in synovial (retinacular) folds

Slipped Capital Femoral Epiphysis (SCFE)

  • Description:

    • Condition during growth where the growth plate of the femur slips backward or inward

    • Ossification: ends of limb bones ossify separately from shafts; fusion terminates growth in length

    • Weak point: avulsion of bony epiphysis

  • Treatment Options:

    • Nonsurgical: casting and immobilization due to the quick healing in children

    • Surgical: stabilizing bone fragments with screws

    • Note: growth plate injury may stimulate bone growth resulting in the injured limb being longer than the uninjured one

Aging of the Hip Joint

  • Joint cartilage tends to become thinner during growth and development

  • Degenerative Joint Disease Implications:

    • Decreased load-bearing capacity

    • Increased likelihood of cartilage abrasion (e.g., bone-on-bone contact)

    • Potential development of bone spurs

    • Inflammation, pain, and loss of mobility

Hip Fractures

  • Types of Hip Fractures:

    • Transcervical fracture of femoral neck

    • Intertrochanteric fracture

    • Spiral fracture

  • Common in elderly populations, particularly females; typically arise from falls

Angle of Inclination

  • Variation:

    • Angle of inclination can vary based on age, sex, ethnicity, and development

    • Aging may lead to decreased angles, which increases susceptibility to fractures

Clinical Example of Hip Injuries

  • Difference between a fractured hip and a dislocated hip

    • Example:

    • Driver in a collision suffers a fractured hip

    • Front seat passenger incurs a dislocated hip

  • Injury Presentations:

    • Hip dislocation (posterior is most common, 90%):

    • Presentation includes medially rotated, shortened lower limb

    • Femoral neck fracture:

    • Presentation includes laterally rotated lower limb and lengthened appearance in case of anterior dislocation

  • Both conditions require immediate treatment to prevent avascular necrosis of the femoral head

Hip Prosthesis (Replacement)

  • Procedure:

    • Lateral hip incision for entry point

    • Removal of injured or damaged femoral head and acetabular articular surfaces

    • Insertion of a prosthetic ball-socket joint, made of metal and/or polyethylene

    • Goals:

    • Restore normal range of motion

    • Ensure durability of at least 15-20 years

Muscles of the Hip and Thigh

  • Muscle Compartments:

    • Muscles are divided into three compartments based on attachments and functionality

  • Joint Crossings:

    • Example: A muscle attaching from pelvis to tibia without femoral attachment crosses two joints (hip and knee)

  • Types of Muscle Contraction:

    • Concentric: brings attachments closer together

    • Isometric: maintains the same position with force

    • Eccentric: forces slow lengthening (deceleration)

  • Innervation:

    • Importance of blood supply and nerve function for muscle functionality

Gluteal Muscles

  • Superficial Group (4 muscles):

    1. Gluteus maximus

    2. Gluteus medius

    3. Gluteus minimus

    4. Tensor fascia lata

  • Deep Group (5 muscles):

    1. Piriformis

    2. Superior gemellus

    3. Obturator internus

    4. Inferior gemellus

    5. Quadratus femoris

Muscle Contraction Types

  • Concentric Contraction:

    • Muscle shortens during contraction, producing movement

  • Eccentric Contraction:

    • Muscle elongates while under tension, controlling movement

  • Isometric Contraction:

    • Muscle remains the same length while tensed, resulting in no movement

Specific Muscles

  • Tensor Fascia Lata Muscle:

    • Attachments:

    • Anterior superior iliac spine and anterior part of the iliac crest

    • Iliotibial tract (extends to lateral condyle of tibia)

    • Functions:

    • Stabilizes hip and knee joint

    • Aids in hip flexion and medial rotation

    • Innervation:

    • Superior gluteal nerve

  • Gluteus Maximus Muscle:

    • Attachments:

    • Tho

  • racolumbar fascia, ilium, sacrum, erector spinae, and sacrotuberous ligament to femur (gluteal tuberosity) and iliotibial tract

    • Function:

    • Hip extension and lateral rotation

    • Innervation:

    • Inferior gluteal nerve

    • Gluteus Medius Muscle:

    • Attachments:

    • Ilium between posterior and anterior gluteal lines to femur (greater trochanter)

    • Function:

    • Abduction and rotation of hip

    • Anterior fibers: abduct and medially rotate

    • Posterior fibers: abduct and laterally rotate

    • Innervation:

    • Superior gluteal nerve

  • Gluteus Minimus Muscle:

    • Attachments:

    • Posterior ilium between anterior and inferior gluteal lines to femur (greater trochanter)

    • Function:

    • Abduction

    • Innervation:

    • Superior gluteal nerve

Gluteal Region Vasculature

  • Arteries:

    • Superior gluteal artery: above piriformis; courses between gluteus medius and minimus

    • Inferior gluteal artery: below piriformis; anastomoses with circumflex femoral arteries around the hip joint

    • Internal iliac arteries supply branches that exit through the greater sciatic foramen

Lateral Rotators of the Hip

  • Muscle Group Includes:

    • Piriformis

    • Superior gemellus

    • Inferior gemellus

    • Obturator internus and externus

    • Quadratus femoris

  • Main Functions:

    • Laterally rotate femur

    • Stabilize femur within acetabulum

Specific Lateral Rotators

  • Piriformis Muscle:

    • Attachments:

    • Sacrum, sacrotuberous ligament to femur (greater trochanter)

    • Innervation:

    • L5-S2

  • Obturator Internus Muscle:

    • Attachments:

    • Pelvis (obturator membrane and its bony edges) to femur (greater trochanter)

    • Innervation:

    • Nerve to obturator internus (L5-S2)

  • Inferior Gemellus Muscle:

    • Attachments:

    • Pelvis (lesser sciatic notch) to femur (greater trochanter)

    • Innervation:

    • Nerve to quadratus femoris (L4-S1)

  • Superior Gemellus Muscle:

    • Attachments:

    • Pelvis (lesser sciatic notch) to femur (greater trochanter)

    • Innervation:

    • Nerve to obturator internus (L5-S2)

  • Quadratus Femoris Muscle:

    • Attachments:

    • Pelvis (ischial tuberosity) to femur (intertrochanteric crest)

    • Innervation:

    • Nerve to quadratus femoris (L4-S1)

Nerve Supply to the Gluteal Region

  • Superior Gluteal Nerve (L4-S1):

    • Innervates gluteus medius, gluteus minimus, and tensor fascia lata

  • Inferior Gluteal Nerve (L5-S2):

    • Innervates gluteus maximus

  • Posterior Cutaneous Nerve of Thigh (S1-S3):

    • A large sensory nerve to posterior thigh and gluteal region

  • Nerve to Obturator Internus (L5-S2):

    • Innervates obturator internus and superior gemellus

  • Nerve to Quadratus Femoris (L4-L5):

    • Innervates inferior gemellus and quadratus femoris

  • Pudendal Nerve (S2-S4):

    • Innervates the perineum

  • Sciatic Nerve (L4-S3):

    • Divides into tibial and common fibular (common peroneal) nerves, which innervate posterior thigh muscles and all muscles below the knee; also provides skin sensation from foot and lateral leg

Gluteal Vasculature

  • Veins:

    • Same pathways as arteries

  • Internal Iliac Artery:

    • Named based on geographic locations relative to the piriformis muscle

    • Branches include superior gluteal artery and inferior gluteal artery

Gluteal Intramuscular (IM) Injections

  • Safest Injection Site:

    • Superior-lateral quadrant of the gluteal region to avoid nerve damage, especially to the sciatic nerve

Piriformis Syndrome

  • Description:

    • Condition where the sciatic nerve is compressed usually as it exits the pelvis inferior to the piriformis muscle

  • Causes of Compression:

    • Prolonged sitting, climbing stairs, walking, or running

  • Symptoms:

    • Pain, tingling or numbness in the buttocks and down the leg

  • Treatment:

    • Anti-inflammatory medication

    • Surgical intervention (piriformis release)

    • Prevention through stretching before exercise

Sciatica

  • Description:

    • Severe, shooting pain radiating along the path of the sciatic nerve, frequently unilaterally

  • Causes:

    • Compression from herniated disk, bone spur, or spinal stenosis

  • Common Symptoms:

    • Radiating pain, inflammation, and numbness in the lower limb

    • Symptoms may be similar to those of piriformis syndrome but can also involve higher spinal levels

  • Treatment:

    • Anti-inflammatory medication

    • Physical therapy

    • Heat/ice application

Standing on One Leg and Trendelenburg Sign

  • Standing Balance:

    • When standing on one leg, the left gluteus medius and minimus generate less than twice the body mass to counterbalance forces

  • Trendelenburg Sign:

    • Indication of weakness in the gluteus medius muscle, potentially due to damage to the superior gluteal nerve; results in the "good" hip dropping when standing on one leg

Summary of Gluteal Muscles

  • Muscle Groups Reviewed:

    • Gluteus maximus, gluteus medius, gluteus minimus, piriformis, tensor fascia lata, and quadratus femoris.

    • Importance of muscular attachments, functions, and innervations for movement and posture control