- The ONC outline has eight condition categories plus six nursing tasks; they intersect and are never added together.
- Degenerative Disorders is the largest condition category at 51 of 135 scored items.
- Pain carries the largest task range, 35-45 items, followed by Complications at 31-41.
- The exam has 150 questions in three hours; 135 are scored, 15 are unscored pretest items.
Why "14 Domains" Is Really Two Axes
Search for the Orthopaedic Nurse - Certified (ONC) content outline and you will see fourteen headings. Treat that number carefully. The Detailed Content Outline in the Orthopaedic Nurses Certification Board (ONCB) Candidate Handbook, January 2026 download, lists eight condition categories and six cross-cutting nursing tasks. They are not fourteen mutually exclusive buckets. Every scored question is classified on both axes at once.
Think of it as a grid. A question about a patient after total knee arthroplasty belongs to the condition category Degenerative Disorders and might simultaneously test the task area Pain (multimodal analgesia), Complications (recognizing deep vein thrombosis), or Activity (weight-bearing and mobility progression). This is why candidates who memorize disease facts without practicing nursing judgment often feel the exam is harder than the outline suggests. If you want the broader picture of how the test feels, see How Hard Is the ONC Exam? Complete Difficulty Guide 2026.
Exam Format and Scoring Facts
The ONC exam is a closed-book, computer-delivered test of 150 multiple-choice questions with three hours of examination time. Of those, 135 are scored and 15 are unscored pretest items that the board is evaluating for future forms. You will not know which are which, so treat every question as live.
The current ONC Exam Description publishes a raw passing threshold of 97 out of 135 scored items. The handbook describes Angoff standard setting and equating, which means the cut score may vary slightly from one form to another so that difficulty stays comparable. Plan to the published number, but do not be surprised by a small form-specific difference. For a deeper treatment, read ONC Passing Score 2026: Exactly What You Need to Pass.
Test-day rules matter too: no calculators or unauthorized reference materials, a valid government photo ID that matches your registration, and breaks that run within the exam clock. A break is not free time, so decide in advance whether you will take one.
The Eight Condition Categories
Condition categories answer the question "what is wrong with the patient?" Their published counts, in outline order, are 51, 26, 15, 11, 12, 7, 7, and 6, totaling 135. Operative orthopaedics is not a separate domain; surgical content is woven into whichever conditions it treats.
Domain 1: Degenerative Disorders (51 items)
By far the heaviest category, nearly three-eighths of the scored exam by count. Expect osteoarthritis, spinal stenosis, degenerative disc disease, and the arthroplasty and spine surgery pathways that treat them.
- Preoperative optimization, perioperative nursing care, and discharge readiness for joint replacement
- Postoperative precautions, positioning, and device management
- Recognizing when an expected postoperative finding becomes a complication
- Nonoperative management, including bracing, injections, and activity modification
Domain 2: Orthopedic Trauma (26 items)
The second-largest category. Fractures, dislocations, and the systemic and local consequences of high-energy and fragility injuries.
- Neurovascular assessment and compartment syndrome recognition
- Immobilization, traction, external fixation, and cast and splint care
- Fat embolism, hemorrhage, and other early trauma concerns
- Open fracture priorities and infection prevention
Domain 3: Sports Injuries (15 items)
Ligament, tendon, meniscal, and soft-tissue injuries, with emphasis on assessment, reconstruction pathways, and rehabilitation progression.
- Common knee, shoulder, and ankle injury patterns
- Postoperative bracing and staged return to activity
- Patient teaching on protecting a repair
Domain 4: Inflammatory Disorders (11 items)
Autoimmune and infectious processes affecting bone, joint, and soft tissue.
- Rheumatoid arthritis and related systemic disease
- Gout and crystal arthropathies
- Osteomyelitis and septic arthritis recognition and treatment priorities
- Medication teaching and monitoring for disease-modifying therapies
Domain 5: Metabolic Bone Disorders (12 items)
Conditions in which the quality or quantity of bone is the central problem.
- Osteoporosis risk factors, screening, and fracture prevention
- Pharmacologic therapy and the teaching that accompanies it
- Paget disease, osteomalacia, and related disorders
- Fall prevention as a nursing intervention
Domain 6: Congenital/Pediatric Disorders (7 items)
A small but distinctive slice. Pediatric orthopaedics rewards candidates who know developmental norms and family-centered teaching.
- Clubfoot, developmental hip dysplasia, and scoliosis
- Casting, bracing, and parent education
- Growth-related considerations in assessment
Domain 7: Musculoskeletal Tumors (7 items)
Benign and malignant bone and soft-tissue tumors, including metastatic disease to bone.
- Pathologic fracture risk and protective measures
- Limb-salvage versus amputation considerations
- Pain, function, and psychosocial care across the treatment course
Domain 8: Neuromuscular Disorders (6 items)
The smallest category by count, covering conditions in which nerve or muscle dysfunction drives orthopaedic problems.
- Cerebral palsy, muscular dystrophy, and spina bifida in the orthopaedic setting
- Contracture prevention, positioning, and mobility aids
- Skin integrity and bowel and bladder considerations
The Six Cross-Cutting Nursing Tasks
Task areas answer "what is the nurse doing?" Their published ranges are Self Care 22-32, Pain 35-45, Complications 31-41, Activity 15-25, Nutrition 3-9, and Psychosocial 3-9. Because these are ranges, the exact number of items per task varies by form.
Domain 9: Self Care (22-32 items)
This is education and independence. Questions ask how you prepare a patient to manage at home: wound and incision care, medication use, assistive devices, adaptive equipment, and recognition of warning signs that need a call to the surgeon. Look for answers that build patient capability rather than simply having the nurse do the task.
Domain 10: Pain (35-45 items)
The largest task range on the exam. Expect assessment across age groups and cognitive levels, multimodal analgesia, opioid safety and side-effect management, regional anesthesia and nerve blocks, nonpharmacologic strategies, and the difference between expected postoperative pain and pain that signals a problem, such as compartment syndrome. Pain questions often disguise themselves as complication questions, so read for the underlying clinical clue.
Domain 11: Complications (31-41 items)
The second-largest task range and the area where prioritization is tested hardest. Typical themes include venous thromboembolism, infection, neurovascular compromise, compartment syndrome, fat embolism, pressure injury, delirium, and hardware or implant problems. The question is rarely just "what is this?" but "what do you do first?"
Domain 12: Activity (15-25 items)
Mobility, weight-bearing status, transfer technique, assistive devices, activity restrictions after arthroplasty or spine surgery, and safe progression with physical and occupational therapy. Know the vocabulary of weight-bearing orders and how to translate them into safe bedside practice.
Domain 13: Nutrition (3-9 items)
A small area, but one that can be earned cheaply. Think bone and wound healing, calcium and vitamin D, protein needs after surgery or trauma, and nutritional risk in older or malnourished patients.
Domain 14: Psychosocial (3-9 items)
Coping, body image after amputation or tumor surgery, caregiver strain, health literacy, cultural considerations, and the emotional effect of chronic pain and disability. These questions usually reward therapeutic communication and patient-centered answers.
How the Axes Intersect on Test Day
The most useful mental model is a stem-and-lens approach. First identify the condition in the stem. Then identify which nursing task the question is really asking about. Finally, choose the answer that best matches orthopaedic nursing priorities: patient safety, neurovascular integrity, early recognition of complications, and patient independence.
Consider a patient on postoperative day one after a hip replacement who reports new calf pain. The condition is degenerative (the reason for surgery), but the task is Complications. A patient who has had a long-bone fracture and reports pain out of proportion that is not relieved by prescribed analgesia is a trauma condition tested through Pain and Complications at once. Practicing this dual classification is the fastest way to move from recall to application. A bank of scenario questions, such as those on our ONC practice test site, trains exactly this skill.
Allocation at a Glance
The table below summarizes the published allocations. Remember that condition counts and task ranges are two views of the same 135 scored items.
| Domain | Axis | Published Allocation |
|---|---|---|
| 1. Degenerative Disorders | Condition | 51 items |
| 2. Orthopedic Trauma | Condition | 26 items |
| 3. Sports Injuries | Condition | 15 items |
| 4. Inflammatory Disorders | Condition | 11 items |
| 5. Metabolic Bone Disorders | Condition | 12 items |
| 6. Congenital/Pediatric Disorders | Condition | 7 items |
| 7. Musculoskeletal Tumors | Condition | 7 items |
| 8. Neuromuscular Disorders | Condition | 6 items |
| 9. Self Care | Task | 22-32 items |
| 10. Pain | Task | 35-45 items |
| 11. Complications | Task | 31-41 items |
| 12. Activity | Task | 15-25 items |
| 13. Nutrition | Task | 3-9 items |
| 14. Psychosocial | Task | 3-9 items |
Two takeaways stand out. Degenerative Disorders alone accounts for 51 of 135 scored items, so arthroplasty and spine care deserve the largest share of your review. And among tasks, Pain and Complications together command the greatest ranges, which means bedside judgment about analgesia and early warning signs is worth more preparation time than the small Nutrition and Psychosocial areas.
Sequencing Your Review by Domain
You do not need a generic study philosophy here; you need an order of attack that follows the item counts. The following sequence front-loads the heaviest categories while threading the high-range tasks through every week. For a broader plan, see the ONC Study Guide 2026: How to Pass on Your First Attempt, and keep the ONC Cheat Sheet 2026 handy for last-week review.
Degenerative Disorders + Pain
- Arthroplasty and spine surgery pathways from preoperative teaching to discharge
- Multimodal analgesia, nerve blocks, and opioid safety
Orthopedic Trauma + Complications
- Fracture management, traction, fixation, and casts
- Compartment syndrome, fat embolism, VTE, and infection recognition
Sports, Inflammatory, and Metabolic Bone
- Ligament and tendon repairs with staged rehabilitation
- Rheumatoid arthritis, gout, osteomyelitis, and osteoporosis therapy
- Self Care teaching points for each condition
Pediatric, Tumors, Neuromuscular, and the Small Tasks
- Congenital and pediatric conditions, bone tumors, and neuromuscular disease
- Activity, Nutrition, and Psychosocial review
- Mixed timed sets to rehearse the three-hour clock
Key Takeaway
Spend your first review hours where the item counts are largest. A candidate who masters Degenerative Disorders, Pain, and Complications has covered the highest-volume part of both axes before touching the smaller categories.
Eligibility, Fees, and Registration Mechanics
Knowing the content is half the battle; the other half is getting a seat. The ONCB requires current unrestricted RN licensure (or the board's specified foreign first-level nurse or equivalency route), two full years of RN experience, and at least 1,000 orthopaedic RN practice hours in the previous three years. A BSN is not required. Your immediate supervisor must sign verification within 180 days of your application. Full details are in ONC Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Applications are submitted through ONCB LearningBuilder, and Meazure Learning provides testing at computer centers or by live remote proctoring, with delivery in the United States, Puerto Rico, and Canada described in the handbook. The initial exam fee is US$325 for eligible full NAON, AANP, NOVA, or CONA members and US$450 for non-members; student and associate memberships do not qualify, and the membership must remain active through the exam. Ordinary retakes cost US$275 for members and US$400 for non-members, and a failed attempt requires at least 90 days before retesting. Compare the numbers in ONC Certification Cost 2026: Complete Pricing Breakdown.
Timing rules are easy to confuse. The handbook distinguishes the 366-day initial application eligibility period from separate 90-day completion, scheduling, and refund provisions; they are not one interchangeable booking window. Check current scheduling guidance in ONC Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
| Item | Detail |
|---|---|
| Questions | 150 (135 scored, 15 unscored pretest) |
| Time | Three hours |
| Published raw passing threshold | 97 of 135 |
| Initial fee (eligible member / non-member) | US$325 / US$450 |
| Ordinary retake fee | US$275 / US$400 |
| Minimum gap between failed attempts | 90 days |
| Certification term | Five years (June 30 expiration rule) |
| CE renewal | 75 contact hours (50+ clinical orthopaedic, max 25 general nursing) |
Frequently Asked Questions
Not in the sense of 14 independent buckets. The ONCB outline has eight condition categories and six nursing tasks. Each scored question is classified on both axes, so the allocations overlap and must not be added together.
Degenerative Disorders is the largest condition category at 51 of 135 scored items. Among nursing tasks, Pain has the largest published range at 35-45 items, followed by Complications at 31-41.
No. Surgical content appears within the relevant condition categories, such as arthroplasty under Degenerative Disorders and fixation under Orthopedic Trauma, and is tested through the six nursing tasks.
The current ONC Exam Description publishes a raw passing threshold of 97 out of 135 scored items. Because of Angoff standard setting and equating, the cut score may differ slightly between forms. See ONC Passing Score 2026 for more.
The ONCB's Official Summary of Certification Statistics 2014-2020 reports 58% for 2020, with 316 passes among 544 examinees. That is neither a 2026 figure nor a verified first-attempt-only rate. Read ONC Pass Rate 2026: What the Data Shows for context.
Mastering the ONC outline means thinking in two dimensions: know your conditions, then know what a nurse must do about them. If you are weighing the credential itself, the analysis in Is the ONC Certification Worth It? Complete ROI Analysis 2026 is a good next read, and you can test your domain-by-domain readiness with realistic scenario questions on the ONC Exam Prep practice test.