Orthopedics and the Skeletal System

Introduction to Orthopedics

Orthopedics is the medical specialty focused on the anatomy, physiology, and diseases of the skeletal and muscular systems. Orthopedists diagnose and treat conditions using medical, surgical, and pharmacological interventions.

• Orthopedics derives from Greek roots: orth/o (straight), ped/o (child), and -ics (knowledge; practice).

• Orthopedists address both congenital and acquired disorders of bones and muscles.

Anatomy of the Skeletal System

Overview of the Skeletal System

The human skeletal system consists of 206 bones and associated structures, providing support, protection, and movement for the body.

• Divided into the axial skeleton (central axis: skull, vertebral column, rib cage) and appendicular skeleton (limbs and girdles).

• Functions include support, protection of organs, movement, mineral storage, and blood cell production.

Axial Skeleton

The axial skeleton forms the central structure of the body, including the skull, vertebral column, and thoracic cage.

• Skull: Composed of cranial and facial bones.

• Vertebral column: Supports the head and trunk, protects the spinal cord.

• Thoracic cage: Protects the heart and lungs.

Cranial Bones

The cranium consists of eight bones that protect the brain and form the structure of the head.

• Frontal bone: Forehead

• Parietal bones (2): Upper sides and posterior

• Occipital bone: Base of the skull

• Temporal bones (2): Sides of the skull

• Sphenoid bone: Central base

• Ethmoid bone: Nasal septum

Facial Bones

Fourteen facial bones support the nose, cheeks, and lips, and form the structure of the face.

• Nasal bones (2): Bridge of the nose

• Vomer: Inferior nasal septum

• Inferior nasal conchae (2): Lateral walls of nasal cavity

• Lacrimal bones (2): Eye sockets near tear glands

• Zygomatic bones (2): Cheekbones

• Maxilla (2 fused): Upper jaw

• Palatine bones (2): Hard palate

• Mandible: Lower jaw, only moveable skull bone

Fontanels

Fontanels are soft spots on an infant's skull where cranial bones have not yet fused, allowing for brain growth and flexibility during birth.

• Anterior fontanel: Large soft spot between frontal bones

• Posterior fontanel: Smaller soft spot between parietal bones

Ossicles and Hyoid Bone

• Ossicles: Three tiny bones (malleus, incus, stapes) in each middle ear, essential for hearing.

• Hyoid bone: Located in the neck, not attached to other bones; supports tongue and muscles of the mouth and throat.

Thoracic Cage

The thoracic cage protects vital organs and supports the upper body.

• Sternum: Central bone with manubrium, body, and xiphoid process

• Ribs: 12 pairs (1-7 true, 8-10 false, 11-12 floating)

Vertebral Column

The vertebral column consists of 33 vertebrae in five regions, providing structural support and protecting the spinal cord.

• Cervical (C1–C7): Neck region

• Thoracic (T1–T12): Upper back

• Lumbar (L1–L5): Lower back

• Sacrum: Five fused vertebrae

• Coccyx: Four fused vertebrae (tailbone)

Appendicular Skeleton

The appendicular skeleton includes the bones of the limbs and girdles, facilitating movement and interaction with the environment.

Shoulder Girdle

• Clavicle: Collarbone, connects sternum to scapula

• Scapula: Shoulder blade, articulates with humerus

Upper Extremity

• Humerus: Upper arm bone

• Radius and Ulna: Forearm bones

• Carpals: Eight wrist bones

• Metacarpals: Five hand bones

• Phalanges: Finger bones (three per finger, two in thumb)

Pelvic Girdle

• Ilium: Superior hip bone

• Ischium: Inferior hip bone

• Pubis: Anterior hip bone

• All three form the acetabulum (hip socket)

Lower Extremity

• Femur: Thigh bone

• Tibia: Shin bone

• Fibula: Thin lateral bone of the lower leg

• Patella: Kneecap

Ankle and Foot

• Tarsals: Seven ankle bones

• Metatarsals: Five midfoot bones

• Phalanges: Toe bones (three per toe, two in hallux/great toe)

Structure of Bone

Bone Tissue and Structure

Bones are composed of osseous tissue, a specialized connective tissue. The structure of a long bone includes several key regions and tissues.

• Periosteum: Outer fibrous membrane

• Diaphysis: Shaft of the bone

• Epiphysis: Ends of the bone

• Cortical (compact) bone: Dense outer layer

• Cancellous (spongy) bone: Less dense, found at ends

• Medullary cavity: Contains yellow bone marrow (fat storage)

• Red bone marrow: Site of blood cell production

Joints, Cartilage, and Ligaments

Types of Joints

Joints (articulations) are connections between bones that allow for varying degrees of movement.

• Suture joints: Immovable, found in the skull

• Symphysis joints: Slightly moveable, e.g., pubic symphysis, intervertebral discs

• Synovial joints: Freely moveable, include hinge (elbow, knee) and ball-and-socket (shoulder, hip)

Joint Structure

• Articular cartilage: Covers bone ends in synovial joints

• Meniscus: Cartilage pad in some synovial joints

• Ligaments: Strong connective tissue bands stabilizing joints

• Synovial membrane: Produces lubricating synovial fluid

Physiology of Bone Growth and Remodeling

Bone Cells and Remodeling

• Osteocytes: Mature bone cells maintaining mineral content

• Osteoclasts: Break down bone tissue, releasing calcium

• Osteoblasts: Build new bone matrix

• Osteogenesis: Process of new bone formation

Bone remodeling is a continuous process, with about 10% of the skeleton replaced each year. In children, bone formation exceeds breakdown; in adults, the rates are balanced; in older adults, breakdown exceeds formation.

Bone and Cartilage Diseases

Types of Bone Fractures

Fractures are breaks in bone integrity, classified by their pattern and severity.

Osteoporosis

Osteoporosis is a disease characterized by decreased bone density and increased fracture risk.

• Bone becomes porous and fragile due to loss of mineral content.

• Common in postmenopausal women and elderly individuals.

Chest and Spine Diseases

Scoliosis

Scoliosis is a lateral curvature of the spine, often diagnosed in childhood or adolescence.

• May cause uneven shoulders, hips, and arm lengths.

• Diagnosis involves physical examination and imaging.

Hallux Valgus and Bunion

Hallux valgus is a lateral deviation of the great toe, often associated with a bunion (painful swelling at the base of the toe).

Clubfoot

Clubfoot (talipes equinovarus) is a congenital deformity where the foot is twisted out of shape or position.

Joints, Cartilage, and Ligament Diseases

Osteoarthritis

Osteoarthritis is a degenerative joint disease characterized by the breakdown of articular cartilage and narrowing of joint space.

• Symptoms include pain, stiffness, and reduced mobility.

Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune disorder causing chronic inflammation and deformity of joints.

• Commonly affects small joints of the hands and feet.

Laboratory, Diagnostic, and Radiologic Procedures

Bone Densitometry

Bone densitometry (DEXA scan) measures bone mineral density to assess osteoporosis risk.

• Common sites: hip, spine, wrist

• Results help guide treatment decisions

Medical and Surgical Procedures

Fracture Management

Fractures are treated with immobilization (casts, splints), reduction (realignment), and sometimes surgery.

• Physical therapy may be needed after healing to restore function.

Range of Motion Assessment

Goniometers are used to measure joint range of motion, important in rehabilitation and diagnosis of joint disorders.

Prosthetics

Prosthetic limbs are custom-designed to replace lost extremities and restore mobility.

Arthroscopic Surgery

Arthroscopy is a minimally invasive surgical procedure for diagnosing and treating joint problems using a fiberoptic camera and instruments.

Hip Replacement

Total hip replacement involves removing the damaged femoral head and acetabulum and replacing them with prosthetic components.

Internal Fixation

Severe fractures may require internal fixation with plates and screws to stabilize bone fragments during healing.

Summary Table: Major Bones of the Human Body

Key Medical Terminology

• Oste/o-: bone

• Arthr/o-: joint

• Chondr/o-: cartilage

• -itis: inflammation

• -ectomy: surgical removal

• -plasty: surgical repair

• -scopy: visual examination