The American Orthopedic Foot and Ankle Score (AOFAS)

Update: On July 29, 2022 the AOFAS Board of Directors published a position statement regarding Patient Reported Outcomes. In their statement, they wrote “Subsequent studies demonstrated their limitations and the AOFAS does not endorse the scale due to insufficient reliability and validity”. You can view the full AOFAS Position Statement here.

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American Orthopedic Foot and Ankle Society Score (AOFAS)

One of the most widely used PRO measures for foot and ankle conditions is the American Orthopedic Foot and Ankle Society Score (AOFAS). Developed in 1994, the clinician-based AOFAS covers four different regions of the foot: The ankle-hindfoot, midfoot, metatarsophalangeal (MTP)-interphalangeal (IP) for the hallux, and MTP-IP for the lesser toes.

These four anatomic regions have their own version of the AOFAS survey. Each c is designed to be used independently of the others. However, each measure is comprised of nine questions and covers three categories: Pain (40 points), function (50 points), and alignment (10 points). These are all scored together for a total of 100 points.

The surveys include a mixture of questions that are both subjective and objective in nature. The pain category which asks patients a single question about their level of pain is subjective, while the alignment category (to be answered by the physician) is objective. The function category, however, consists of 5-7 questions and requires completion by both the patient and the physician. Unlike other outcome measures which fall into a single category, AOFAS is a clinician reporting tool that requires both patient and provider participation to be fully complete.

The AOFAS is not a patient-reported outcome measure (PROM) and when created, it was designed for physicians to help standardize the assessments of patients with foot or ankle disorders. Since its inception, however, it has gained widespread popularity. Unfortunately, some concerns have been raised with regard to its validity and reliability.

In 2006, SooHoo et al. found that AOFAS scores correlated poorly with the extensively studied and validated Medical Outcomes Shortform-36 (SF-36) [1] and they called into question how robust the AOFAS tool really was. At the same time, more recent studies have contradicted this assertion and found that some level of correlation between both scoring systems does exist –particularly in specific cases such as the evaluation of an Achilles Ruptures following treatment by Percutaneous Technique [2].

To bridge this gap, although the AOFAS questionnaire has yet to be validated, and no direct correlations have ever been firmly established between itself and other outcome measures, many clinicians continue to administer the AOFAS survey to patients simultaneously with other reporting surveys [3].

Strengths

The four AOFAS scales continue to be some of the most widely-used instruments in clinical studies, and they remain in use at a substantially higher rate than other scales that have been validated [4]. Both the ankle and hindfoot measures are easy to apply and understand and because of their wide use in the literature, AOFAS score values still offer the best comparison between different studies.

Considerations

AOFAS is not a PRO measure but is instead clinician-reported. Although it is a highly rated outcome instrument, more physicians are turning towards the use of PRO measures to assist them in evaluating patient outcomes. It’s also becoming increasingly evident that clinician-reported surveys are unlikely to fully reflect how a patient feels or functions, and are also limited by their insight, reproducibility, and lack of consistency. Additionally, the use of PROs in clinical practice has been found to improve patient-clinician communication and can affect care and outcomes [6].

One consideration of the AOFAS scales is that they are still not validated instruments.  Additionally, there has been some concern that the interpretation of scoring is not straightforward and that in order to fully interpret the values received by a patient using an AOFAS instrument, either normative data or a large sample of similar disease data is at times needed for reference [3]. To help address this, various authors established arbitrary subgroups of scores to defining what ‘excellent’, ‘good’, and ‘fair’ outcomes may correlate to. For instance, some authors have stated that scores between 90 and 100 points represent an ‘excellent’ result while 80 to 90 points are indicative of a ‘good’ result [3]. At the same time, however, the value of an ‘acceptable’ result is still widely disputed and tends to vary significantly depending on the literature that one review [3].

Lastly, there is no consensus on what magnitude of change in the AOFAS score represents a significant clinical change and improvement in the patient’s function [3].

These two issues highlight one of the main critiques of the AOFAS clinician-reported tool –its subjectivity and the increased likelihood that the interpretation of patient scores and the perception of patient improvement may at times vary greatly amongst physicians and researchers.

Despite this, the AOFAS clinician-reporting measures continue to be the consensus survey instrument amongst a wide range of healthcare providers that are used for measuring outcomes with regard to ankle and foot pathology.

License

The AOFAS PRO Measure does not require a license and is free to use.

References