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EDUCATION MEDICAL & TRAINING CAMPUS

DEPARTMENT OF THE ARMY, UNITED STATES OF AMERICA

MEDICAL EDUCATION & TRAINING CAMPUS

PTT 104 Orthopedic Management I

Unit 8: Orthopedic Management of the Hip

Lesson 8.1 Anatomy and Kinesiology of the Hip and Pelvis

Objectives

• Objective 8.1.1: Identify the bony anatomy of the hip and pelvis.

• Objective 8.1.2: Describe the kinematics of the hip and pelvis, including joint type, degrees of freedom, and motions.

• Objective 8.1.3: Identify the muscles of the hip and pelvis, including origin, insertion, innervation, primary blood supply, and actions.

Objective 8.1.1 - Identify the Bony Anatomy of the Hip and Pelvis

Pelvic Girdle

• Composition:

  • Consists of four bones:

  • Sacrum

  • Coccyx

  • Two innominate bones

• Innominate Bone:

  • Formed by the fusion of three irregularly shaped bones:

  • Ilium

  • Ischium

  • Pubis

Sacrum

• Shape: Wedge-shaped, composed of five fused sacral vertebrae.

• Key Features:

  • Body:

  • Sacral Promontory: Ridge projecting along the anterior edge of the body of S1.

  • Auricular (Articular) Surface: On the lateral surface, articulates with the ilium.

  • Coccyx.

Sacrum Anatomy

• Base: Superior surface of S1.

• Superior Articular Processes: Located on the posterior side of the base, articulating with the inferior articular processes of L5 vertebrae.

• Ala (Wings): Lateral fused wings that are actually fused transverse processes.

• Foramina: Openings located on the anterior and dorsal aspects of the sacrum; serve as exits for the anterior and posterior divisions of sacral nerves.

Ilium

• Shape: Fan-shaped and is the superior most aspect of the innominate.

• Features:

  • Iliac Fossa: Concave area on the internal surface for the iliopsoas attachment.

  • Auricular Surface: Articular surface with the sacrum.

  • Iliac Tuberosity: Roughened area for ligamental attachment between the iliac crest and auricular surface.

• Innominate Bone Structures:

  • Iliac Crest: Superior ridge from ASIS to PSIS.

  • ASIS: Attachment site of TFL, sartorius, inguinal ligament.

  • AIIS: Attachment site of rectus femoris.

  • PSIS: Attachment site for sacroiliac ligaments.

  • PIIS: Below PSIS, for sacrotuberous ligament.

Ischium

• Components:

  • Ischial Body: Superior to the tuberosity; forms two-fifths of the acetabulum.

  • Ischial Ramus: Connects medially to the inferior ramus of the pubis; muscle attachments: adductor magnus, obturator externus, obturator internus.

  • Ischial Spine: Between greater and lesser sciatic notches; ligamental attachment.

  • Ischial Tuberosity: Weight-bearing surface during sitting; attaches hamstring and adductor magnus.

  • Lesser Sciatic Notch: Smaller concavity located between the greater sciatic notch and ischial tuberosity.

Pubis

• Structure: Forms the anterior inferior portion of the innominate; divided into three parts:

  • Body: Main portion forming one-fifth of acetabulum, attachment for obturator internus.

  • Superior Ramus: Between acetabulum and pubic body, attachment for pectineus.

  • Inferior Ramus: Connects to inferior pubic ligament, in addition to adductor muscles (magnus, brevis) and gracilis.

• Pubic Features:

  • Pubic Tubercle: Anterior projection for ligamental attachments.

  • Pubic Symphysis: Cartilaginous joint connecting pubic bones at anterior midline.

Acetabulum and Obturator Foramen

• Acetabulum: Deep, cup-shaped cavity articulates with femur.

• Obturator Foramen: Large opening surrounded by ischium and pubis; serves as a passage for blood vessels and nerves.

Femur

• Description: Longest, strongest, and heaviest bone in the body; forms hip joint with innominate bone.

• Features:

  • Femoral Head: Rounded portion with articular cartilage attaching to acetabulum.

  • Femoral Neck: Narrow location between head and trochanters.

  • Greater Trochanter: Lateral projection for muscle attachment (gluteus medius, minimus, etc.).

  • Lesser Trochanter: Medial projection for iliopsoas attachment.

  • Intertrochanteric Crest: Smooth ridge for quadratus femoris.

  • Femoral Shaft: Long cylindrical part.

  • Condyles and Epicondyles: Include medial/lateral condyles and epicondyles for knee articulation.

Objective 8.1.2 Describe the Kinematics of the Hip and Pelvis

Pelvic Articulations

• Joints:

  • Left and right sacroiliac joints

  • Pubic symphysis

  • Lumbosacral joint

Movement Types

• Motions: Include anterior pelvic tilt, posterior pelvic tilt, and lateral tilt (Trendelenburg sign).

• SI Joint: Synovial, non-axial joint transmitting upper body weight; designed for stability.

• Pubic Symphysis: Cartilaginous joint designed for stability with little movement.

• Lumbosacral Joint: Carries similar properties to the vertebrae; limits rotation and anterior translation through ligament types.

Hip Kinematics

• Hip Joint Type: Synovial, ball-and-socket with tri-axial degrees of freedom.

• Normal Range of Motion (ROM):

  • Flexion: 120-130 degrees

  • Extension: 15-20 degrees

  • Abduction: 40-55 degrees

  • Adduction: 20-25 degrees

  • Internal Rotation: 30-45 degrees

  • External Rotation: 40-45 degrees

Objective 8.1.3 Identify the Muscles of the Hip and Pelvis

Anterior Compartment Muscles

• Iliopsoas:

  • Origin: Iliac fossa, anterior and lateral surfaces of T12-L5

  • Insertion: Lesser trochanter

  • Innervation: Femoral nerve

  • Action: Hip flexion

• Rectus Femoris:

  • Origin: AIIS

  • Insertion: Tibial tuberosity via patellar tendon

  • Innervation: Femoral nerve

  • Action: Hip flexion and knee extension

• Vastus Muscles (Lateralis, Medialis, Intermedius):

  • Origin for all: Linea Aspera

  • Insertion: Tibial tuberosity via patellar tendon

  • Innervation: Femoral nerve

  • Action: Knee extension

• Sartorius:

  • Origin: ASIS

  • Insertion: Proximal medial tibia

  • Innervation: Femoral nerve

  • Action: Flexes, abducts, externally rotates hip and flexes knee.

Medial Compartment Muscles

• Pectineus:

  • Origin: Superior ramus of pubis

  • Insertion: Pectineal line of femur

  • Action: Hip adduction

  • Innervation: Femoral nerve

• Adductor Muscles (Magnus, Longus, Brevis):

  • Origin and Insertion vary (all originate from pubis or ischium)

  • Action: Hip adduction

  • Innervation: Primarily obturator nerve, except Pectineus (femoral nerve).

• Gracilis:

  • Origin: Pubis

  • Insertion: Proximal tibia

  • Action: Hip adduction

  • Innervation: Obturator nerve.

Posterior Compartment Muscles

• Gluteus Maximus:

  • Origin: Posterior sacrum and ilium

  • Insertion: Gluteal tuberosity

  • Action: Hip extension and external rotation

  • Innervation: Inferior gluteal nerve

• Hamstring Muscles (Semimembranosus, Semitendinosus, Biceps Femoris):

  • Origin usually: Ischial tuberosity

  • Insertion varies with structures.

  • Action: Hip extension and knee flexion (differ based on muscle).

  • Innervation: Sciatic nerve for Semimembranosus and Semitendinosus; Biceps Femoris innervated by sciatic and common fibular nerves where applicable.

Lateral Compartment Muscles

• Gluteus Medius:

  • Origin: Outer surface of ilium

  • Insertion: Greater trochanter

  • Action: Hip abduction

  • Innervation: Superior gluteal nerve.

• Gluteus Minimus:

  • Origin: Lateral surface of ilium

  • Insertion: Anterior aspect of Greater Trochanter

  • Action: Hip abduction and internal rotation.

• Tensor Fascia Latae:

  • Origin: ASIS

  • Insertion: Lateral condyle of tibia

  • Action: Hip flexion, abduction, internal rotation.

  • Innervation: Superior gluteal nerve.

Blood Supply

• General Supply: All thigh musculature receives blood from deep artery of the thigh (profunda femoris artery).

• Gluteal Muscles: Supplied by superior and inferior gluteal arteries.

Summary of Objectives

• Objective 8.1.1: Identify all bony and ligamentous structures of the hip and pelvis.

• Objective 8.1.2: Understand kinematic properties of the hip and pelvis, including specific movements and joint types.

• Objective 8.1.3: Detail the musculature of the hip and pelvis, including innervation and blood supply.