Osgood-Schlatter disease (traction apophysitis)


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Osgood-Schlatter disease (traction apophysitis)

Ortopedia 2020!

Ortopedia 2020!

Introduction to biostatistics


Types of data

Mean, median, and mode

Range, variance, and standard deviation

Normal distribution and z-scores

Standard error of the mean (Central limit theorem)

Paired t-test

Two-sample t-test

Hypothesis testing: One-tailed and two-tailed tests

Sensitivity and specificity

Positive and negative predictive value

Test precision and accuracy

Incidence and prevalence

Relative and absolute risk

Odds ratio

Attributable risk (AR)

Mortality rates and case-fatality


Direct standardization

Indirect standardization

Ecologic study

Cross sectional study

Case-control study

Cohort study

Randomized control trial

Sample size

Placebo effect and masking

Disease causality

Selection bias

Information bias



Modes of infectious disease transmission

Outbreak investigations

Disease surveillance

Vaccination and herd immunity


Linear regression

Logistic regression

Type I and type II errors



Oncogenes and tumor suppressor genes

Metaplasia and dysplasia


Gene regulation

Introduction to the immune system


Innate immune system

Complement system

B-cell development

T-cell development


Antibody classes

B-cell activation and differentiation

Somatic hypermutation and affinity maturation

T-cell activation

VDJ rearrangement

MHC class I and MHC class II molecules

Cell-mediated immunity of CD4 cells

Cell-mediated immunity of natural killer and CD8 cells

Contracting the immune response and peripheral tolerance

B- and T-cell memory

Type I hypersensitivity

Food allergy


Type II hypersensitivity

Serum sickness

Type III hypersensitivity

Type IV hypersensitivity

Graft-versus-host disease

Hypersensitivity pneumonitis

Chronic granulomatous disease

Leukocyte adhesion deficiency

Complement deficiency

X-linked agammaglobulinemia

Wiskott-Aldrich syndrome

Selective immunoglobulin A deficiency

Isolated primary immunoglobulin M deficiency

Hyper IgM syndrome

Thymic aplasia

DiGeorge syndrome

Adenosine deaminase deficiency


Non-corticosteroid immunosuppressants and immunotherapies

Staphylococcus aureus

Staphylococcus epidermidis

Staphylococcus saprophyticus

Streptococcus pneumoniae

Streptococcus pyogenes (Group A Strep)

Streptococcus agalactiae (Group B Strep)

Streptococcus viridans


Clostridium perfringens

Clostridium botulinum (Botulism)

Clostridium tetani (Tetanus)

Listeria monocytogenes

Bacillus anthracis (Anthrax)

Bacillus cereus (Food poisoning)

Corynebacterium diphtheriae (Diphtheria)


Actinomyces israelii

Escherichia coli

Salmonella (non-typhoidal)

Salmonella typhi (typhoid fever)

Pseudomonas aeruginosa


Bartonella henselae (Cat-scratch disease and Bacillary angiomatosis)

Klebsiella pneumoniae


Proteus mirabilis

Yersinia enterocolitica

Legionella pneumophila (Legionnaires disease and Pontiac fever)

Serratia marcescens

Bacteroides fragilis

Yersinia pestis (Plague)

Helicobacter pylori

Vibrio cholerae (Cholera)

Campylobacter jejuni

Neisseria meningitidis

Neisseria gonorrhoeae

Moraxella catarrhalis

Francisella tularensis (Tularemia)

Bordetella pertussis (Pertussis/Whooping cough)


Haemophilus influenzae

Haemophilus ducreyi (Chancroid)

Pasteurella multocida

Mycobacterium tuberculosis (Tuberculosis)

Mycobacterium leprae

Mycoplasma pneumoniae

Chlamydia trachomatis

Chlamydia pneumoniae

Treponema pallidum (Syphilis)


Borrelia burgdorferi (Lyme disease)

Borrelia species (Relapsing fever)

Rickettsia rickettsii (Rocky Mountain spotted fever) and other Rickettsia species

Coxiella burnetii (Q fever)

Ehrlichia and Anaplasma

Ehrlichia and Anaplasma

Gardnerella vaginalis (Bacterial vaginosis)



Epstein-Barr virus (Infectious mononucleosis)

Herpes simplex virus


Varicella zoster virus

Human herpesvirus 8 (Kaposi sarcoma)

Human herpesvirus 6 (Roseola)


Parvovirus B19

Viral hepatitis: Pathology review

Hepatitis D virus

Human papillomavirus

Poxvirus (Smallpox and Molluscum contagiosum)

JC virus (Progressive multifocal leukoencephalopathy)

BK virus (Hemorrhagic cystitis)




Viral hepatitis: Pathology review

Influenza virus

Measles virus

Mumps virus

Respiratory syncytial virus

Human parainfluenza viruses

West Nile virus

Dengue virus

Yellow fever virus

Zika virus

Hepatitis C virus

Viral hepatitis: Pathology review



COVID-19 (Coronavirus Disease 19)



Human T-lymphotropic virus

Ebola virus

Rabies virus

Rubella virus

Eastern and Western equine encephalitis virus

Eastern and Western equine encephalitis virus

Lymphocytic choriomeningitis virus


Prions (Spongiform encephalopathy)


Plasmodium species (Malaria)

Trypanosoma cruzi (Chagas disease)

Protein synthesis inhibitors: Aminoglycosides

Antimetabolites: Sulfonamides and trimethoprim

Antituberculosis medications

Miscellaneous cell wall synthesis inhibitors

Cell wall synthesis inhibitors: Cephalosporins

DNA synthesis inhibitors: Metronidazole

DNA synthesis inhibitors: Fluoroquinolones

Miscellaneous protein synthesis inhibitors

Cell wall synthesis inhibitors: Penicillins

Protein synthesis inhibitors: Tetracyclines



Miscellaneous antifungal medications

Anti-mite and louse medications

Anthelmintic medications


Integrase and entry inhibitors

Herpesvirus medications

Hepatitis medications

Protease inhibitors

Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

Nucleoside reverse transcriptase inhibitors (NRTIs)

Neuraminidase inhibitors

Heart failure: Pathology review

Aortic dissections and aneurysms: Pathology review

Cyanotic congenital heart defects: Pathology review

Cardiac and vascular tumors: Pathology review

Endocarditis: Pathology review

Vasculitis: Pathology review

Heart blocks: Pathology review

Cardiomyopathies: Pathology review

Dyslipidemias: Pathology review

Deep vein thrombosis and pulmonary embolism: Pathology review

Pericardial disease: Pathology review

Hypertension: Pathology review

Coronary artery disease: Pathology review

Acyanotic congenital heart defects: Pathology review

Peripheral artery disease: Pathology review

Platelet disorders: Pathology review

Mixed platelet and coagulation disorders: Pathology review

Coagulation disorders: Pathology review

Non-hemolytic normocytic anemia: Pathology review

Macrocytic anemia: Pathology review

Microcytic anemia: Pathology review

Extrinsic hemolytic normocytic anemia: Pathology review

Myeloproliferative disorders: Pathology review

Leukemias: Pathology review

Plasma cell disorders: Pathology review

Lymphomas: Pathology review

Intrinsic hemolytic normocytic anemia: Pathology review

Thrombosis syndromes (hypercoagulability): Pathology review

Pancreatitis: Pathology review

Cirrhosis: Pathology review

Appendicitis: Pathology review

Malabsorption syndromes: Pathology review

Gastrointestinal bleeding: Pathology review

Gallbladder disorders: Pathology review

Colorectal polyps and cancer: Pathology review

Esophageal disorders: Pathology review

Congenital gastrointestinal disorders: Pathology review

GERD, peptic ulcers, gastritis, and stomach cancer: Pathology review

Diverticular disease: Pathology review

Jaundice: Pathology review

Sjogren syndrome: Pathology review

Scleroderma: Pathology review

Bone tumors: Pathology review

Systemic lupus erythematosus (SLE): Pathology review

Neuromuscular junction disorders: Pathology review

Bone disorders: Pathology review

Gout and pseudogout: Pathology review

Myalgias and myositis: Pathology review

Back pain: Pathology review

Skeletal system anatomy and physiology

Cartilage structure and growth

Bone remodeling and repair

Fibrous, cartilage, and synovial joints

Muscular system anatomy and physiology

Muscle contraction

Slow twitch and fast twitch muscle fibers

Sliding filament model of muscle contraction

Neuromuscular junction and motor unit

Rheumatoid arthritis

Reactive arthritis

Psoriatic arthritis


Calcium pyrophosphate deposition disease (pseudogout)

Ankylosing spondylitis

Juvenile idiopathic arthritis

Systemic lupus erythematosus


Raynaud phenomenon

Limited systemic sclerosis (CREST syndrome)

Sjogren syndrome


Mixed connective tissue disease

Polymyalgia rheumatica




Inclusion body myopathy


Slipped capital femoral epiphysis

Paget disease of bone

Osteomalacia and rickets


Osgood-Schlatter disease (traction apophysitis)

Legg-Calve-Perthes disease

Septic arthritis


Lordosis, kyphosis, and scoliosis

Rotator cuff tear

Meniscus tear

Compartment syndrome

Bone tumors

Developmental dysplasia of the hip

Cleidocranial dysplasia


Acetaminophen (Paracetamol)

Antigout medications

Non-steroidal anti-inflammatory drugs

Osteoporosis medications

Nephrotic syndromes: Pathology review

Renal and urinary tract masses: Pathology review

Urinary incontinence: Pathology review

Renal failure: Pathology review

Renal tubular acidosis: Pathology review

Congenital renal disorders: Pathology review

Urinary tract infections: Pathology review

Kidney stones: Pathology review

Nephritic syndromes: Pathology review

Renal tubular defects: Pathology review

Acid-base disturbances: Pathology review

Pediatric brain tumors: Pathology review

Movement disorders: Pathology review

Headaches: Pathology review

Adult brain tumors: Pathology review

Vertigo: Pathology review

Neurocutaneous disorders: Pathology review

Central nervous system infections: Pathology review

Seizures: Pathology review

Demyelinating disorders: Pathology review

Traumatic brain injury: Pathology review

Congenital neurological disorders: Pathology review

Parathyroid disorders and calcium imbalance: Pathology review

Thyroid nodules and thyroid cancer: Pathology review

Hyperthyroidism: Pathology review

Diabetes insipidus and SIADH: Pathology review

Hypopituitarism: Pathology review

Cushing syndrome and Cushing disease: Pathology review

Pituitary tumors: Pathology review

Hypothyroidism: Pathology review

Diabetes mellitus: Pathology review

Adrenal insufficiency: Pathology review

Multiple endocrine neoplasia: Pathology review

Adrenal masses: Pathology review

Prostate disorders and cancer: Pathology review

Breast cancer: Pathology review

Testicular tumors: Pathology review

Cervical cancer: Pathology review

Uterine disorders: Pathology review

Complications during pregnancy: Pathology review

Vaginal and vulvar disorders: Pathology review

Ovarian cysts and tumors: Pathology review

Respiratory distress syndrome: Pathology review

Pneumonia: Pathology review

Cystic fibrosis: Pathology review

Tuberculosis: Pathology review

Lung cancer and mesothelioma: Pathology review

Nasal, oral and pharyngeal diseases: Pathology review

Obstructive lung diseases: Pathology review

Coronary artery disease: Clinical (To be retired)

Heart failure: Clinical (To be retired)

Syncope: Clinical (To be retired)

Hypertension: Clinical (To be retired)

Pericardial disease: Clinical (To be retired)

Infective endocarditis: Clinical (To be retired)

Valvular heart disease: Clinical (To be retired)

Cardiomyopathies: Clinical (To be retired)

Hypercholesterolemia: Clinical (To be retired)

Aortic aneurysms and dissections: Clinical (To be retired)

Asthma: Clinical (To be retired)

Chronic obstructive pulmonary disease (COPD): Clinical (To be retired)

Diffuse parenchymal lung disease: Clinical (To be retired)

Acute respiratory distress syndrome: Clinical (To be retired)

Pleural effusion: Clinical (To be retired)

Lung cancer: Clinical (To be retired)

Pneumonia: Clinical (To be retired)

Venous thromboembolism: Clinical (To be retired)

Anemia: Clinical (To be retired)

Leukemia: Clinical (To be retired)

Lymphoma: Clinical (To be retired)

Thrombocytopenia: Clinical (To be retired)

Blood products and transfusion: Clinical (To be retired)

Thrombophilia: Clinical (To be retired)

Bleeding disorders: Clinical (To be retired)

Myeloproliferative neoplasms: Clinical (To be retired)

Plasma cell disorders: Clinical (To be retired)

Diabetes mellitus: Clinical (To be retired)

Hyperthyroidism: Clinical (To be retired)

Hypothyroidism and thyroiditis: Clinical (To be retired)

Thyroid nodules and thyroid cancer: Clinical (To be retired)

MEN syndromes: Clinical (To be retired)

Cushing syndrome: Clinical (To be retired)

Adrenal masses and tumors: Clinical (To be retired)

Pituitary adenomas and pituitary hyperfunction: Clinical (To be retired)

Hypopituitarism: Clinical (To be retired)

Adrenal insufficiency: Clinical (To be retired)

Systemic lupus erythematosus (SLE): Clinical (To be retired)

Rheumatoid arthritis: Clinical (To be retired)

Joint pain: Clinical (To be retired)

Seronegative arthritis: Clinical (To be retired)

Vasculitis: Clinical (To be retired)

Inflammatory myopathies: Clinical (To be retired)

Sjogren syndrome: Clinical (To be retired)

Gallbladder disorders: Clinical (To be retired)

Esophagitis: Clinical (To be retired)

Esophageal disorders: Clinical (To be retired)

Gastroesophageal reflux disease (GERD): Clinical (To be retired)

Peptic ulcers and stomach cancer: Clinical (To be retired)

Diarrhea: Clinical (To be retired)

Malabsorption: Clinical (To be retired)

Inflammatory bowel disease: Clinical (To be retired)

Gastroparesis: Clinical (To be retired)

Colorectal cancer: Clinical (To be retired)

Diverticular disease: Clinical (To be retired)

Pancreatitis: Clinical (To be retired)

Gastrointestinal bleeding: Clinical (To be retired)

Viral hepatitis: Clinical (To be retired)

Jaundice: Clinical (To be retired)

Cirrhosis: Clinical (To be retired)

Hyponatremia: Clinical (To be retired)

Hypernatremia: Clinical (To be retired)

Hyperkalemia: Clinical (To be retired)

Hypokalemia: Clinical (To be retired)

Acute kidney injury: Clinical (To be retired)

Chronic kidney disease: Clinical (To be retired)

Kidney stones: Clinical (To be retired)

Metabolic and respiratory acidosis: Clinical (To be retired)

Renal cysts and cancer: Clinical (To be retired)

Urinary tract infections: Clinical (To be retired)

Parathyroid conditions and calcium imbalance: Clinical (To be retired)

Nephritic and nephrotic syndromes: Clinical (To be retired)

Stroke: Clinical (To be retired)

Meningitis, encephalitis and brain abscesses: Clinical (To be retired)

Hyperkinetic movement disorders: Clinical (To be retired)

Hypokinetic movement disorders: Clinical (To be retired)

Seizures: Clinical (To be retired)

Headaches: Clinical (To be retired)

Dementia and delirium: Clinical (To be retired)

Dizziness and vertigo: Clinical (To be retired)

Disorders of consciousness: Clinical (To be retired)

Muscle weakness: Clinical (To be retired)

Brain tumors: Clinical (To be retired)

Lower back pain: Clinical (To be retired)

Mood disorders: Clinical (To be retired)

Schizophrenia spectrum disorders: Clinical (To be retired)

Anxiety disorders: Clinical (To be retired)

Sleep disorders: Clinical (To be retired)

Eating disorders: Clinical (To be retired)

Obsessive compulsive disorders: Clinical (To be retired)

Trauma- and stressor-related disorders: Clinical (To be retired)

Personality disorders: Clinical (To be retired)

Dissociative disorders: Clinical (To be retired)

Disruptive, impulse-control and conduct disorders: Clinical (To be retired)

Substance misuse and addiction: Clinical (To be retired)

Sexual dysfunctions: Clinical (To be retired)

Paraphilic disorders: Clinical (To be retired)

Neurodevelopmental disorders: Clinical (To be retired)

Sickle cell disease: Clinical (To be retired)

Pediatric bone tumors: Clinical (To be retired)

Pediatric constipation: Clinical (To be retired)

Cystic fibrosis: Clinical (To be retired)

Pediatric infectious rashes: Clinical (To be retired)

Kawasaki disease: Clinical (To be retired)

Pediatric lower airway conditions: Clinical (To be retired)

Vaccinations: Clinical (To be retired)

Congenital adrenal hyperplasia: Clinical (To be retired)

Pediatric allergies: Clinical (To be retired)

BRUE, ALTE, and SIDS: Clinical (To be retired)

Child abuse: Clinical (To be retired)

Pediatric upper airway conditions: Clinical (To be retired)

Pediatric gastrointestinal bleeding: Clinical (To be retired)

Neonatal jaundice: Clinical (To be retired)

Skin and soft tissue infections: Clinical (To be retired)

Newborn management: Clinical (To be retired)

Pediatric orthopedic conditions: Clinical (To be retired)

Pediatric vomiting: Clinical (To be retired)

Congenital heart defects: Clinical (To be retired)

Fever of unknown origin: Clinical (To be retired)

Developmental milestones: Clinical (To be retired)

Immunodeficiencies: Clinical (To be retired)

Pediatric ophthalmological conditions: Clinical (To be retired)

Congenital disorders: Clinical (To be retired)

Neonatal ICU conditions: Clinical (To be retired)

Pediatric ear, nose, and throat conditions: Clinical (To be retired)

Precocious and delayed puberty: Clinical (To be retired)

Pediatric bone and joint infections: Clinical (To be retired)

Pediatric urological conditions: Clinical (To be retired)

Perinatal infections: Clinical (To be retired)

Virilization: Clinical (To be retired)

Contraception: Clinical (To be retired)

Breast cancer: Clinical (To be retired)

Postpartum hemorrhage: Clinical (To be retired)

Hypertensive disorders of pregnancy: Clinical (To be retired)

Infertility: Clinical (To be retired)

Gestational trophoblastic disease: Clinical (To be retired)

Sexually transmitted infections: Clinical (To be retired)

Vulvovaginitis: Clinical (To be retired)

Abnormal uterine bleeding: Clinical (To be retired)

Routine prenatal care: Clinical (To be retired)

Premature rupture of membranes: Clinical (To be retired)

Abnormal labor: Clinical (To be retired)

Vaginal versus cesarean delivery: Clinical (To be retired)

Antepartum hemorrhage: Clinical (To be retired)

Preoperative evaluation: Clinical (To be retired)

Postoperative evaluation: Clinical (To be retired)

Abdominal pain: Clinical (To be retired)

Appendicitis: Clinical (To be retired)

Esophageal surgical conditions: Clinical (To be retired)

Bowel obstruction: Clinical (To be retired)

Hernias: Clinical (To be retired)

Anal conditions: Clinical (To be retired)

Leg ulcers: Clinical (To be retired)

Peripheral vascular disease: Clinical (To be retired)

Advanced cardiac life support (ACLS): Clinical (To be retired)

Pneumothorax: Clinical (To be retired)

Traumatic brain injury: Clinical (To be retired)

Neck trauma: Clinical (To be retired)

Chest trauma: Clinical (To be retired)

Shock: Clinical (To be retired)

Abdominal trauma: Clinical (To be retired)

Burns: Clinical (To be retired)

Bites and stings: Clinical (To be retired)

Toxidromes: Clinical (To be retired)

Methods of regression analysis

Study designs


Eczematous rashes: Clinical (To be retired)

Hypersensitivity skin reactions: Clinical (To be retired)

Papulosquamous skin disorders: Clinical (To be retired)

Hypopigmentation skin disorders: Clinical (To be retired)

Blistering skin disorders: Clinical (To be retired)

Autoimmune bullous skin disorders: Clinical (To be retired)

Benign hyperpigmented skin lesions: Clinical (To be retired)

Skin cancer: Clinical (To be retired)


Osgood-Schlatter disease (traction apophysitis)


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USMLE® Step 1 questions

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High Yield Notes

16 pages


Osgood-Schlatter disease (traction apophysitis)

of complete


USMLE® Step 1 style questions USMLE

of complete

A 14-year-old boy is brought to his primary pediatrician for evaluation of left knee pain. He plays basketball for his high school team, and the pain started four weeks following the start of the season. The pain is worsened with running and jumping and relieved with rest. He has no significant past medical history. Vitals are within normal limits. He is at the 75th percentile for height and 40th percentile for weight. Physical examination reveals anterior knee pain located at the position of the arrow, as seen in the image below. Which of the following best describes the etiology of this patient’s condition?

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External References

First Aid






Osgood-Schlatter disease p. 462


Content Reviewers

Rishi Desai, MD, MPH


Evode Iradufasha, MD

Marisa Pedron

Tanner Marshall, MS

Osgood-Schlatter disease is an inflammation of the patellar ligament, right at the point where it inserts on the tibial tuberosity, resulting in painful swelling just below the knee.

It’s named after two orthopedic surgeons; the American Robert Osgood, and the Swiss Carl Schlatter.

So focusing in on the knee, the proximal epiphysis of the tibia, which is the upper end of the tibia that contributes to the knee joint, has a bony prominence called the tibial tuberosity.

This is considered an apophysis, meaning that it’s a bony prominence that serves as a site for tendon attachment.

The tibial tuberosity specifically serves as the attachment site for the patellar ligament, which is an extension of the quadriceps muscle tendon.

When the patellar ligament contracts, it extends the knee.

At birth, the proximal epiphysis consists of cartilage, but it contains an ossification center inside.

This ossification center begins to ossify or turn to bone between the ages of nine and fifteen, and becomes a bony tuberosity around the age of eighteen.

Osgood-Schlatter disease typically develops between the ages of nine and fifteen years old when the tuberosity hasn’t ossified yet, and therefore isn’t hard enough to resist traction of the patellar ligament.

So, this is why the disease is very common in young adolescents who play sports requiring the quadriceps muscles to contract repetitively, causing the patellar ligament to excessively strain on the not-yet-ossified tibial tuberosity.

This results in inflammation of the ligament at the point it inserts to the tuberosity, what is known as traction apophysitis.


Osgood-Schlatter disease is a common condition that affects the knee in adolescents, typically during the growth spurt that occurs just before puberty. It is caused by repetitive traction of the patella ligament on the tibial tuberosity, causing it to become inflamed, which results in a painful swelling just under the knee.

People with Osgood-Schlatter disease with a palpable lump below the knee, which gets very painful with physical activities like running, jumping, squatting, and especially when going up or down stairs, or when the knee gets hit by something. The treatment consists of reducing physical activity and applying ice to the tuberosity to reduce swelling, as well as pain medication. Rarely, surgery may be necessary, especially if fragmented bones have avulsed off, and get trapped within the patella ligament.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Apophysitis of the Tibial Tuberosity (Osgood-Schlatter Disease): A Review" Cureus (2016)
  6. "Treatment of Osgood–Schlatter disease: review of the literature" MUSCULOSKELETAL SURGERY (2017)
  7. "Prevalence and Associated Factors of Osgood-Schlatter Syndrome in a Population-Based Sample of Brazilian Adolescents" The American Journal of Sports Medicine (2010)

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