Olerud-Molander Ankle Score (OMAS)
- Fysiobasen
- Sep 18
- 3 min read
The Olerud-Molander Ankle Score (OMAS) is a patient-reported outcome measure (PROM) developed to assess symptoms and function following ankle fractures. The tool was first introduced in 1984 by Olerud and Molander and is among the most widely used outcome measures in orthopedic rehabilitation for this patient population【1】. The primary purpose of OMAS is to provide healthcare professionals with a simple, quick, and objective assessment of a patient’s status and functional recovery after an ankle injury.
By evaluating functional level on a scale from 0 to 100, OMAS can help track progress during treatment, evaluate outcomes after surgical or conservative management, and compare the effectiveness of different interventions. This makes it a valuable tool in both clinical practice and research.
Target population
OMAS is specifically designed for adult patients who have sustained an ankle fracture, including those treated surgically or conservatively. The scoring system is also useful for identifying persistent functional limitations and symptoms that may require further intervention.
The tool is primarily used in the follow-up phase after injury but can also be applied in long-term evaluations to assess functional outcomes and potential complications.
Administration and method
Questions and scoring
OMAS consists of nine questions, each addressing specific aspects of symptoms and function. Each domain contributes to the total score:
Pain: 0–25 points
Evaluates pain intensity at rest and during activity.
25 = no pain; 0 = unbearable pain.
Stiffness: 0–10 points
Measures joint stiffness, particularly in the morning or after inactivity.
Higher score = minimal stiffness.
Swelling: 0–10 points
Assesses swelling of the ankle during weight-bearing or at rest.
10 = no swelling.
Stair climbing: 0–10 points
Evaluates the ability to climb stairs without aids or pain.
Running: 0–5 points
Measures ability to run on flat and uneven surfaces.
Jumping: 0–5 points
Assesses capacity to jump, requiring strength, balance, and mobility.
Squatting: 0–5 points
Evaluates ability to perform deep squats without discomfort.
Support use: 0–10 points
Assesses the need for crutches, braces, or other aids for walking.
Work and activity level: 0–20 points
Evaluates ability to perform daily activities and occupational tasks.
Maximum score = 100 → optimal function and no symptoms.Lower scores → increasing functional limitations and symptoms.
Test procedure
Patient instructions:The patient completes the questionnaire by rating their symptoms and functional level in each category. It usually takes less than 10 minutes.
Responses should reflect the patient’s symptoms and function during the last 24 hours.
Each category must be clearly understood and answered as honestly as possible.
Healthcare staff may assist with clarification, but answers must be patient-driven.
Important considerations:
As a self-reported instrument, OMAS depends on the patient’s subjective evaluation. Clear instructions are critical.
For patients with limited literacy, the questions may be read aloud by healthcare personnel.
Psychometric properties
Reliability
OMAS demonstrates high reliability across multiple studies, making it a robust tool for evaluating functional outcomes after ankle fractures【2】:
Test–retest reliability: ρ = 0.95, ICC = 0.94
Standard error of measurement (SEM): Low, at 4.4 points (5.8%)【2】
Internal consistency: Moderate (Cronbach’s α = 0.76)
Validity
OMAS shows strong concurrent validity compared to other ankle outcome measures such as the Foot and Ankle Outcome Score (FAOS):
Correlation with FAOS subscales: ρ = 0.80–0.86【2】
Significant differences in Global Self-Rating Function (GSRF) between groups (“good,” “fair,” “poor”) at both 6- and 12-month follow-up (p < 0.001)【2】
Responsiveness
OMAS is sensitive to clinical changes over time:
Effect size between 6- and 12-month follow-up: medium (0.4)【2】
Clinical use and advantages
Applications
Post-surgical follow-up: Evaluating recovery after operative fixation of ankle fractures.
Conservative management: Assessing outcomes of non-surgical rehabilitation programs.
Long-term monitoring: Identifying persistent impairments or late complications, such as post-traumatic osteoarthritis.
Advantages
Easy to administer: Quick completion, no special equipment needed.
Patient-centered: Captures the patient’s own perception of function and symptoms.
Validated and reliable: High measurement accuracy and consistency.
Limitations
Less suitable for complex injuries involving multiple joints or severe complications.
As a self-reported tool, responses may be influenced by subjectivity or recall bias.
Sources:
Olerud C, Molander H. A scoring scale for symptom evaluation after ankle fracture. Archives of Orthopaedic and Traumatic Surgery. 1984;103:190–194.
Nilsson GM, Eneroth M, Ekdahl CS. The Swedish version of OMAS is a reliable and valid outcome measure for patients with ankle fractures. BMC Musculoskeletal Disorders. 2013;14:1–8.
