Orthopedics and the Skeletal System: Medical Terminology Study Guide

Orthopedics: Medical Specialty

Definition and Scope

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 methods.

• Orth/o: means straight

• Ped/o: means child

• -ics: means knowledge; practice

Skeletal System Overview

General Structure

The skeletal system consists of 206 bones and associated structures, forming a connected framework throughout the body. It provides support, protection, and facilitates movement.

• Axial skeleton: Central structure (head, neck, chest, spine)

• Appendicular skeleton: Limbs (shoulder, arm, hip, leg)

Anatomy of the Axial Skeleton

Cranial and Facial Bones

The skull is composed of cranial and facial bones, protecting the brain and supporting facial structures.

• Cranial bones: 8 bones forming the cranium

• Facial bones: 14 bones supporting the nose, cheeks, and jaw

Fontanels in Infants

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

• Anterior fontanel: Large open space between frontal bones

• Posterior fontanel: Smaller open space between parietal bones

Chest and Rib Cage

The chest is formed by the sternum and ribs, protecting vital organs such as the heart and lungs.

• Sternum: Manubrium, body, xiphoid process

• Ribs: 12 pairs (true, false, floating)

Spinal Column

The spine is a vertical column of vertebrae, supporting the body and protecting the spinal cord. It is divided into five regions.

• Cervical (C1–C7): Neck

• Thoracic (T1–T12): Chest

• Lumbar (L1–L5): Lower back

• Sacrum: Five fused vertebrae

• Coccyx: Tailbone

Anatomy of the Appendicular Skeleton

Shoulder and Upper Extremity

The shoulder consists of the clavicle and scapula, connecting the arm to the trunk. The upper extremity includes the humerus, radius, and ulna.

• Clavicle: Collarbone

• Scapula: Shoulder blade

• Humerus: Upper arm bone

• Radius and Ulna: Forearm bones

Hip and Lower Extremity

The hip is formed by the ilium, ischium, and pubis, which together create the acetabulum. The lower extremity includes the femur, tibia, fibula, and patella.

• Ilium: Superior hip bone

• Ischium: Inferior hip bone

• Pubis: Anterior hip bone

• Femur: Thigh bone

• Tibia: Shin bone

• Fibula: Thin bone of lower leg

• Patella: Kneecap

Ankle, Foot, and Toes

The ankle and foot contain numerous small bones, providing support and flexibility for movement.

• Tarsal bones: 7 in the ankle

• Metatarsal bones: 5 in the midfoot

• Phalanges: 3 in each toe, 2 in the hallux (great toe)

Structure of Bone

Osseous Tissue and Bone Anatomy

Bone is a specialized connective tissue composed of osseous tissue. The surface is covered by periosteum, and long bones have a diaphysis (shaft) and epiphyses (ends).

• Cortical bone: Dense, weight-bearing

• Cancellous bone: Spongy, less dense

• Medullary cavity: Contains yellow bone marrow

• Epiphyseal plates: Sites of bone growth

Joints, Cartilage, and Ligaments

Types of Joints

Joints (articulations) are locations where two bones meet. They are classified by their mobility and structure.

• Suture joints: Immovable (cranial bones)

• Symphysis joints: Slightly movable (pubis, vertebrae)

• Synovial joints: Fully movable (hinge, ball-and-socket)

Joint Structure and Function

Synovial joints contain articular cartilage, a meniscus (in some joints), and are stabilized by ligaments. The joint capsule contains a synovial membrane that produces synovial fluid for lubrication.

• Articular cartilage: Covers bone ends

• Meniscus: Cartilage pad in some joints

• Ligaments: Connect bones

• Synovial fluid: Lubricates joint

*Additional info: Ball-and-socket joints allow multidirectional movement; hinge joints allow movement in two directions.*

Physiology of Bone Growth

Bone Cells and Remodeling

Bone growth and maintenance involve specialized cells and continuous remodeling.

• Osteocytes: Maintain bone mineral content

• Osteoclasts: Break down bone tissue

• Osteoblasts: Build new bone tissue

• Osteogenesis: Formation of new bone

About 10% of the skeleton is remodeled annually. Calcium is stored in bone and released as needed for muscle function and repair.

Bone Growth Across the Lifespan

• Pediatric patients: Bone formation exceeds breakdown; growth occurs at epiphyseal plates

• Adults: Formation equals breakdown

• Older adults: Breakdown exceeds formation

Bone and Cartilage Diseases

Fractures

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

• Colles fracture: Distal radius fracture

• Comminuted fracture: Bone shattered into multiple pieces

• Compression fracture: Bone collapses, often in vertebrae

• Depressed fracture: Bone pressed inward, typically in skull

• Greenstick fracture: Partial fracture, common in children

• Hairline fracture: Thin crack in bone

• Oblique fracture: Diagonal break

• Transverse fracture: Straight across bone

Osteoporosis

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

• Normal bone: Dense, strong

• Osteoporotic bone: Porous, weak, prone to fracture

Chest and Spine Diseases

Scoliosis

Scoliosis is a lateral curvature of the spine, which can cause uneven shoulders, hips, and arm lengths. Diagnosis involves physical examination and imaging.

• Dextroscoliosis: Curve to the right

• Screening: Forward-bend test, x-rays

Bones of the Lower Extremity: Common Disorders

Hallux Valgus and Bunion

Hallux valgus is a lateral deviation of the great toe, often accompanied by a bunion, which is a painful swelling at the base of the toe.

Clubfoot

Clubfoot is a congenital deformity where the foot is rotated inward and downward. Treatment may require surgery.

Joints, Cartilage, and Ligaments Diseases

Osteoarthritis

Osteoarthritis is a degenerative joint disease characterized by loss of articular cartilage, narrowing of joint space, and malalignment of bone ends.

• Normal joint: Adequate joint space

• Degenerative joint: Narrowed space, bone changes

Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune disease causing severe joint deformities, especially in the hands.

Laboratory, Diagnostic, and Radiologic Procedures

Bone Densitometry

Bone densitometry is a radiologic test used to measure bone mineral density and assess osteoporosis risk.

• DXA scan: Dual-energy x-ray absorptiometry

• Hip and spine: Common sites for measurement

Medical Procedures

Cast Application and Crutches

Casts are applied to immobilize fractured bones. Patients may use crutches and require physical therapy after healing.

Goniometer Use

A goniometer is used by physical therapists to measure the range of motion in joints, aiding in rehabilitation assessment.

Leg Prosthesis

Prosthetic legs are custom-built for patients after amputation, allowing for mobility and rehabilitation.

Surgical Procedures

Arthroscopic Surgery

Arthroscopy is a minimally invasive surgical procedure using an arthroscope to visualize and treat joint conditions.

Hip Prostheses

Total hip replacement involves removing the head of the femur and replacing it with a prosthetic stem and ball, which fits into a prosthetic cup in the acetabulum.

Orthopedic Plate and Screws

Fractures may be stabilized using metal plates and screws, which hold bone fragments in place during healing.

Appendix: Pediatric Office Visit Charts

Vital Signs and Growth Percentiles

Pediatric office visits include measurement of vital signs and calculation of growth percentiles using CDC standards.

Vital Sign	Value
Temperature (Oral)	98.4 °F
Pulse	105
Respirations	26
Blood Pressure	112/78
Oxygen Saturation	99%
Height	4' 2.79" (>99th percentile)
Weight	78 lb 14.4 oz (>99th percentile)
BMI	21.51 (>99th percentile)

Key Formulas

BMI Calculation for Children and Teens

Body Mass Index (BMI) is calculated as follows:

• $\text{BMI} = \frac{\text{weight (lb)} \times 703}{\text{height (in)}^2}$

*Additional info: CDC provides online calculators for pediatric BMI percentiles.*