Responsiveness and Validity of the SF-36, Ankle Osteoarthritis Scale, AOFAS Ankle Hindfoot Score, and Foot Function Index in End Stage Ankle Arthritis

Abstract

Background: We examined four commonly used scores, the SF-36, the Ankle Osteoarthritis Scale (AOS), the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle Hindfoot Score, and the Foot Function Index (FFI) to determine their responsiveness and validity. Methods: Patients with end stage ankle arthritis were recruited into a prospective multicenter cohort study and baseline and one year outcome scores were compared. The Standardized Response Mean and Effect Size for the AOS, AOFAS, and FFI were calculated and the three region- or disease-specific scores were compared with the SF-36 to determine their criterion validity. Results: All four scores showed acceptable responsiveness, and when using the validated SF-36 as the standard the three region or disease specific scores all showed similar criterion validity. Conclusion: All four scores are responsive and can be considered for use in this population. The objective component of the AOFAS Ankle Hindfoot Score may make it harder to perform than the other three scores which have subjective components only, and as yet its objective component has not been shown to demonstrate reliability. We recommend use of a purely subjective score such as the Ankle Osteoarthritis Scale or Foot Function Index as the region- or disease-specific score of choice in this population. As the SF-36 shows acceptable responsiveness, using it alone could also be considered. Level of Evidence: II, Prospective Comparative Study

The foot function index is more sensitive to change than the Leeds Foot Impact Scale for evaluating rheumatoid arthritis patients after forefoot or hindfoot reconstruction

“…The present literature describes 36 different PROMs used to measure foot problems in RA patients; solely five instruments were measured for responsiveness [9]. A worldwide (USA, Europe, Australia and Asia) used PROM to measure the impact of foot pathology on function in terms of pain, difficulty and activity restriction is the Foot Function Index [10,11] as described by Budiman et al Nelson et al reported moderate to large responsiveness of the FFI in RA patients receiving foot or ankle surgery; however, they did not specify the operative procedure [12]. The responsiveness of the FFI in end stage ankle arthritis patients, who received either a total ankle replacement or an ankle arthrodesis, showed a high level of responsiveness (both the standardized effect size and standardized response mean above the threshold of 0.8 indicating a high level of responsiveness) [13].…”

Validity, Reliability, and Responsiveness of the Korean Version of American Academy of Orthopedic Surgeons Foot and Ankle Questionnaire

“…Second, the data obtained with these questions might not accurately represent the patient's status, because the physician's expectations could influence the data. Third, if the physician completing these objective elements has not been properly trained, the reliability of the results could be threatened (14). In contrast, the AFAQ consists entirely of questions related to subjective discomfort; thus, it is advantageous regarding the procurement of data that effectively measures the patient's status.…”

“…The AOFAS scale studies reported the scales could evaluate the outcomes of surgery (12), and their subjective component had acceptable validity (13). However, other studies have reported that the AOFAS scales are difficult to perform and lack reliability (14), validity, and precision (15)(16)(17).…”

Evidence-Based Rationale for Ankle Cartilage Allograft Replacement: A Systematic Review of Clinical Outcomes

“…The AOFAS scale includes both subjective and objective methods of evaluation and has been shown to be a valuable tool in assessing pre-and postoperative ankle function. Madeley et al (27) compared several commonly used scoring systems, including the AOFAS scale, the Medical Outcomes Study short-form 36-item questionnaire, the AOS, and the foot function index, and found all 4 scores to be a valid method of assessment. However, the objective portion of the AOFAS has not been shown to be reliable and can often be difficult to perform on patients with severe ankle arthritis.…”