100+ Free CO Practice Questions

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During a patient assessment, which gait deviation is most commonly associated with weak hip abductors?

Trendelenburg gait

Steppage gait

Antalgic gait

Circumduction gait

to track

2026 Statistics

Key Facts: CO Exam

200

Written Exam Questions

ABC Practitioner Candidate Guide

3.5 hours

Written Exam Time

ABC Practitioner Candidate Guide

$1,725

Total Exam Fees

ABC Fee Schedule

$78,310

Median Annual Salary

BLS (May 2024)

13%

Job Growth (2024-2034)

BLS Occupational Outlook

80 credits

CE Credits per 5-Year Cycle

ABC Continuing Education

ABC lists the Prosthetist Orthotist Written Exam as a 200-question, 3.5-hour multiple-choice exam. Full CO certification requires passing three exams: written ($300 + $250 application), simulation ($300 + $100 application), and CPM ($775 + $100 application). The BLS reports a median salary of $78,310 for orthotists and prosthetists in 2024, with 13% projected job growth from 2024 to 2034.

Sample CO Practice Questions

Try these sample questions to test your CO exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1During a patient assessment, which gait deviation is most commonly associated with weak hip abductors?

A.Trendelenburg gait

B.Steppage gait

C.Antalgic gait

D.Circumduction gait

Explanation: Trendelenburg gait is characterized by a pelvic drop on the unsupported side during single-limb stance, caused by weakness of the hip abductors (primarily the gluteus medius). This is a critical finding during patient assessment that may indicate the need for a hip orthosis or HKAFO.

2What is the primary purpose of manual muscle testing during an orthotic patient evaluation?

A.To determine the patient's cardiovascular fitness

B.To assess the strength of specific muscle groups to guide orthotic design

C.To measure joint range of motion

D.To evaluate the patient's cognitive function

Explanation: Manual muscle testing (MMT) is performed during orthotic patient evaluation to assess the strength of specific muscle groups. The results directly inform orthotic design decisions, such as determining the level of support needed and whether the orthosis should be rigid or articulated.

3A patient presents with a diagnosis of drop foot due to peroneal nerve palsy. Which orthotic device is most appropriate?

A.KAFO with locked knee

B.AFO with dorsiflexion assist

C.Hip orthosis

D.TLSO

Explanation: An AFO (ankle-foot orthosis) with dorsiflexion assist is the most appropriate device for drop foot caused by peroneal nerve palsy. The dorsiflexion assist feature compensates for the weak or paralyzed dorsiflexors by providing a spring-loaded or posterior leaf spring mechanism to lift the foot during swing phase.

4In a three-point force system used in orthotic design, how many forces act on the body segment?

A.Two forces in opposite directions

B.Three forces with the middle force opposing the two end forces

C.Four forces distributed evenly

D.One force applied at the center of the segment

Explanation: A three-point force system consists of three forces, where the middle (corrective) force acts in the opposite direction to the two end (counterforces). This is the fundamental biomechanical principle underlying most orthotic designs, creating a controlled bending moment to correct or prevent deformity.

5Which material is most commonly used for fabricating custom rigid AFOs?

A.Low-temperature thermoplastic

B.Polypropylene

C.Silicone

D.Leather

Explanation: Polypropylene is the most commonly used material for custom rigid AFOs due to its excellent combination of rigidity, durability, lightweight properties, and ability to be vacuum-formed over a positive model. It can be easily molded at elevated temperatures and maintains its shape under load.

6What does the abbreviation TLSO stand for in orthotic nomenclature?

A.Thoracolumbosacral orthosis

B.Total lower spinal orthosis

C.Therapeutic lumbar support orthosis

D.Trunk lateral stabilization orthosis

Explanation: TLSO stands for thoracolumbosacral orthosis. This spinal orthosis controls motion across the thoracic, lumbar, and sacral regions of the spine. TLSOs are commonly used for conditions such as compression fractures, post-surgical stabilization, and scoliosis management.

7Which assessment finding would indicate the need for a total-contact orthosis rather than a standard padded orthosis?

A.Patient has normal sensation throughout the affected limb

B.Patient has insensate skin with diabetes-related neuropathy

C.Patient has full muscle strength in the affected limb

D.Patient prefers a lightweight device

Explanation: A total-contact orthosis distributes pressure evenly across the entire surface area, which is critical for patients with insensate skin (such as in diabetic neuropathy). These patients cannot feel pressure points that could lead to skin breakdown, making even pressure distribution essential to prevent ulceration.

8During gait analysis, the stance phase begins with which event?

A.Toe off

B.Heel strike (initial contact)

C.Midswing

D.Terminal swing

Explanation: The stance phase of gait begins with heel strike (also called initial contact), when the foot first contacts the ground. Stance phase comprises approximately 60% of the gait cycle and includes initial contact, loading response, midstance, terminal stance, and pre-swing.

9A Certified Orthotist receives a prescription for a KAFO for a patient with quadriceps weakness. Which knee joint mechanism would allow the patient to sit down most easily?

A.Drop-lock ring lock

B.Bail lock (Swiss lock)

C.Offset knee joint

D.Ratchet lock

Explanation: A bail lock (Swiss lock) mechanism uses a posterior bail that extends behind both uprights and allows the patient to unlock both knee joints simultaneously by pushing the bail against a chair when sitting. This makes it the most convenient option for patients who need to lock and unlock the knee frequently.

10What is the standard manual muscle testing grade for a muscle that can complete full range of motion against gravity but not against resistance?

A.Grade 2 (Poor)

B.Grade 3 (Fair)

C.Grade 4 (Good)

D.Grade 5 (Normal)

Explanation: Grade 3 (Fair) on the manual muscle testing scale indicates that the muscle can complete full range of motion against gravity but cannot tolerate any additional manual resistance. This is the minimum grade needed for functional movement against gravity.

About the CO Exam

The ABC Certified Orthotist (CO) credential certifies allied health professionals who evaluate patients, formulate orthotic treatment plans, design, fabricate, and fit orthotic devices such as braces, supports, and splints. The certification pathway includes a written multiple-choice exam, a simulation exam, and a hands-on Clinical Patient Management (CPM) exam.

Questions

200 scored questions

Time Limit

3.5 hours (written exam)

Passing Score

Criterion-referenced (set by expert panel)

Exam Fee

$1,725 total (written $550, simulation $400, CPM $875) (ABC (American Board for Certification in Orthotics, Prosthetics & Pedorthics))

CO Exam Content Outline

28%

Patient Assessment

Comprehensive clinical evaluation including patient history, manual muscle testing, gait analysis, sensory function, range of motion, joint stability, and skin integrity assessment

18%

Formulation of the Treatment Plan

Evaluating findings to determine orthotic treatment goals, selecting design, materials, and components, consulting with healthcare providers, and documenting the treatment plan

27%

Implementation of the Treatment Plan

Fabricating and fitting orthotic devices, selecting materials, performing measurements and impressions, aligning and assessing devices, and educating patients on use and maintenance

15%

Follow-up to the Treatment Plan

Periodic reassessment of patient function, skin condition, orthosis fit and alignment, making modifications, and developing long-term follow-up plans

12%

Practice Management

Compliance with federal and state regulations (CMS, HIPAA, FDA, ADA, OSHA), personnel policies, documentation, financial records, and professional ethics

How to Pass the CO Exam

What You Need to Know

Passing score: Criterion-referenced (set by expert panel)
Exam length: 200 questions
Time limit: 3.5 hours (written exam)
Exam fee: $1,725 total (written $550, simulation $400, CPM $875)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CO Study Tips from Top Performers

1Focus heavily on Patient Assessment (28%) and Implementation (27%) domains, which together comprise over half the written exam content

2Master lower extremity orthotics thoroughly, as it represents 54% of orthotic practice according to the ABC practice analysis

3Study biomechanical principles including three-point force systems, ground reaction forces, and gait analysis phases

4Practice clinical reasoning with case scenarios to prepare for both the written and simulation exams

5Review spinal orthotics nomenclature (LSO, TLSO, CTLSO) and scoliosis management, which are heavily tested

Frequently Asked Questions

How many questions are on the ABC CO written exam?

The Prosthetist Orthotist Written Exam is a 200-question, multiple-choice exam with a 3.5-hour time limit. It covers anatomy, physiology, biomechanics, kinesiology, disease processes, pathologies, prescription criteria, material science, ethics, and professionalism.

What are the three exams required for CO certification?

ABC CO certification requires passing three exams: (1) the Written Multiple Choice Exam (200 questions, 3.5 hours), (2) the Simulation Exam (7 case scenarios, 3 hours), and (3) the Clinical Patient Management (CPM) Exam (three 60-minute hands-on practical modules at the ABC Testing Center in Tampa, FL).

What are the prerequisites for the ABC CO exam?

Candidates must hold a master's degree in orthotics and prosthetics from a CAAHEP-accredited program (or equivalent foreign degree evaluated by WES) and complete a 12-month single-discipline or 18-month dual-discipline NCOPE-accredited clinical residency.

How much does it cost to become a Certified Orthotist?

The total exam fees are approximately $1,725: Written Exam application ($250) + exam ($300), Simulation application ($100) + exam ($300), and CPM application ($100) + exam ($775). An annual renewal fee of $330 is required once certification is awarded.

What is the passing score for the ABC CO exams?

ABC uses criterion-referenced scoring where the passing score is set by a geographically diverse panel of practicing certified practitioners under the guidance of testing experts. The passing score represents the minimum knowledge level for competent practice. Exact numeric passing scores are not publicly disclosed.

What is the difference between CO and CPO certifications?

CO (Certified Orthotist) is a single-discipline credential for orthotics only, covering braces, supports, and splints. CPO (Certified Prosthetist Orthotist) is a dual-discipline credential covering both orthotics and prosthetics. CPO requires passing exams in both disciplines and completing an 18-month dual-discipline residency.

How much do Certified Orthotists earn?

According to BLS data for 2024, orthotists and prosthetists earned a median annual salary of $78,310. The lowest 10% earned less than $46,220, while the highest 10% earned more than $118,730. Job growth is projected at 13% from 2024 to 2034, much faster than average.