Translation, cross-cultural adaptation, and analysis of the measurement properties of the Fremantle Knee Awareness Questionnaire (FreKAQ) into Brazilian Portuguese for individuals with knee osteoarthritis

Abstract

Objective

This study aimed to translate and cross-culturally adapt the Fremantle Knee Awareness Questionnaire (FreKAQ) into Brazilian Portuguese and evaluate the measurement properties, including internal consistency, construct validity, reliability, and ceiling and floor effects in individuals with knee osteoarthritis (KOA). Methods: Translation, cross-cultural adaptation, and analysis of measurement properties were performed according to international recommendations. One hundred thirty-four individuals diagnosed with KOA participated in the study. Of these, 30 participated in the validation process of the pre-final version of the FreKAQ. One hundred four were evaluated with the FreKAQ, the Numeric Pain Rating Scale (NPRS), the Pain Catastrophizing Scale (PCS), the International Knee Documentation Committee (IKDC), and the 36-item short-form survey (SF-36). The construct validity was tested using Spearman’s correlation coefficient, and ceiling and floor effects were calculated. A subsample of 54 participants participated in the reproducibility assessment. Internal consistency was calculated using Cronbach’s alpha. Reproducibility was assessed using the test-retest model using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimum detectable change (MDC). Results: the FreKAQ showed a favorable correlation with the construct’s intensity and catastrophizing related to pain and activities of daily living (p < 0.01). It also had the functional capacity, pain, social aspects, and emotional aspects of the SF-36 (p < 0.05). Additionally, it presented excellent ICC (0.91) and adequate internal consistency (0.91) with the SEM and MDC scores, respectively, 2.86 and 7.94. There were no ceiling or floor effects. Conclusion: The FreKAQ showed adequate measurement properties in individuals with KOA, indicating its use as an evaluative measure of body perception of the knee.

Introduction

Pain is considered the most significant factor that impairs the integrity of body perception since the constant harmful nociceptive stimulus in the emergence of the pathophysiology of this condition generates changes in temporal summation and impairs perceptive sensitization, especially in joints such as the knee [1,2,3,4]. Additionally, individuals who suffer from knee osteoarthritis (KOA), even though they do not have anatomical changes in global or local ligament laxity, report altered body perceptions. The higher the pain level, the more significant the change in perception in these individuals. The prevalence of this change in self-reported perception is 60%, associated with sensory changes in the knee and muscle weakness in the lower limb. This results in a continuous cycle with the perception of knee instability, muscle weakness, deficit in muscle activation, and consequently, a greater risk of falling [5, 6].

When evaluated in neuroimaging studies, individuals with KOA confirm morphological and functional changes in cortical areas with a loss of gray matter in the morphological structure of the entire brain and functional reorganization in neuronal networks and the motor cortex. These changes promote symptoms including impaired body perception, reduced tactile acuity, reorganization in the laterality of the affected limb, and deficits in degraded proprioceptive acuity [7,8,9,10,11,12,13,14].

This evidence on the impairment of central structures and components of the central nervous system in individuals with KOA is analyzed and confirmed through neuroimaging exams, often making the assessment logistically and financially unfeasible. For this reason, more functional tests and patient-reported outcome measures (PROMs) are created based on analyzing various outcomes related to body perception. Among these PROMs, one of the most prominent in recent years is The Fremantle Knee Awareness Questionnaire (FreKAQ) [15].

Initially created and developed in Australian English, the FreKAQ has been translated, cross-culturally adapted, and validated in Italian [16], Persian [17], and Japanese [14]. The FreKAQ assesses body perception in individuals’ KOA regarding their affected joints. Fundamentally, the FreKAQ is used to evaluate whether there are distortions in knee perception and how these distortions may be related to pain, movement limitations, and the progression of KOA.

Therefore, the translation process, cross-cultural adaptation, validity, and reliability of the FreKAQ represent critical steps in the availability and use of a new instrument to assess body perception of the knee in the Brazilian population with KOA. If these measurement properties prove adequate, a new assessment resource will be available to bring new options for the health system, clinicians, researchers, and individuals with KOA. The health system can use a simple, low-implementation, and easily applicable assessment tool to compose the most diverse clinical scenarios, evolving a better understanding of body perception, pain, and functionality. Clinicians and researchers responsible for therapeutic planning can achieve a greater likelihood of assertiveness and accuracy in assessing their patients and research participants about body perception. Due to its novelty, it can offer individuals with KOA an improvement in understanding their condition, providing benefits for self-management.

This study aimed to translate and cross-culturally adapt the Fremantle Knee Awareness Questionnaire (FreKAQ) into Brazilian Portuguese and evaluate the measurement properties, including internal consistency, construct validity, reliability, and ceiling and floor effects in individuals with KOA.

Methods

Study design and ethical considerations

This study was a translation, cross-cultural adaptation, and analysis of measurement properties. The cross-cultural validation and adaptation of the questionnaire was conducted per the Guidelines for the Process of Cross-cultural Adaptation of Self-Report Measures [18] and Consensus-based Standards for the Selection of Health Measurement Instruments [19]. These recommendations establish a sample size of at least seven times the number of items in the questionnaire if this value is at least 100 participants. It is possible to perform the reproducibility analysis from half of this reference value, i.e., 50 participants.

The research was performed in the integrated health outpatient clinics of Nove de Julho University by Resolution of the National Health Council, and the procedures reported here were approved by the Research Ethics Committee of the same institution, registered under 47658121.2.0000.5511.

Participants

The following inclusion criteria were adopted: (1) both genders; (2) age between 40 and 80 years; (3) pain in one or both knees; (4) feeling of pain for at least three months; (5) diagnosis of unilateral or bilateral knee osteoarthrosis based on the criteria established by the American College of Rheumatology [20]; (6) native speaker of Brazilian Portuguese, ability to read and write in Brazilian Portuguese; (7) radiographic confirmation for grades 2 or 3 of the Kellgren-Lawrence Classification [21]. The following exclusion criteria were adopted: (1) previous surgery on the knee affected by pain; (2) any severe pathology (unhealed fracture, tumor, acute trauma to the knee, or severe illness); (3) musculoskeletal dysfunctions resulting from neurological changes (muscle weakness and/or loss of sensitivity); (4) diagnosed psychiatric disorders; (5) inability to provide consent; (6) cancer, diabetes, acute adverse health conditions that prevent exercise and/or use of a walking assistance device.

Assessments

The translation, cross-cultural adaptation, and validation processes consisted of three phases:

• Phase 1: two translators (a physiotherapist and an English language teacher) with 10 and 20 years of experience, respectively, performed independent translations. Both have Brazilian Portuguese as their native language and are fluent in English. The two translators were blinded from contact and access to the individual translations. Next, the translations were synthesized, and the responsible researcher coordinated discussions and revisions with the two translators (native English speakers) to produce a single version. Therefore, the back-translation was performed independently and without access to the original version of the FreKAQ by two other translators fluent in Brazilian Portuguese without technical knowledge in the health area. Finally, four physiotherapists with around ten years of experience in assessing and managing individuals with KOA met with the four translators participating in the previous stages. Everyone approved the pre-final version of the FreKAQ.

• Phase 2: With the pre-final version defined, 30 individuals meeting the study inclusion criteria read and completed the FreKAQ. In the end, they characterized each question as understandable or not understandable. When a question was described as not understandable, the reason was explained.

• Phase 3: The final version of the FreKAQ was applied together with the NPRS (Numeric Pain Rating Scale), PCS (Pain catastrophizing Scale), IKDC (International Knee Documentation Committee), and SF-36 (36-item short form survey) in 104 individuals with KOA. The 104 individuals participated in the validity-related processes, which tested for construct validity and ceiling and floor effects. The last 54 individuals, sequentially evaluated in the study, participated in the reliability analysis process regarding internal consistency, reproducibility, and measurement error. Thus, the PROMs were applied twice within a 7-day interval to analyze reliability. These PROMs were chosen due to their respective constructs’ specificities, the validity of their psychometric properties, and their broad applicability in clinical research.

The FreKAQ is a one-dimensional questionnaire comprising nine questions that assess knee perception in space, knee awareness during daily activities, and the interference of pain in body perception. All questions are scored using a Likert scale, from 0 to 4 points, in ascending order. Therefore, a total score between 0 and 36 is possible. The higher the score, the greater the levels of distorted body perception specific to the knee [15,16,17,18].

The NPRS, initially developed in English and then translated and adapted into Brazilian Portuguese, is a short and easy-to-apply scale [22]. This scale has only one domain (pain) and consists of 11 points, scored from 0 to 10, where 0 means “no pain,” and 10 means “the worst possible pain.”

The PCS is one of the most used scales studied in individuals with chronic pain. The PCS is a scale composed of 13 questions about the individual’s thoughts and sensations regarding pain. Responses are categorized using a Likert scale from 0 to 4, where 0 is “Minimal,” 1 is “Light,” 2 is “Moderate,” 3 is “Intense,” and four is “Very intense.” The higher the score, the worse the individual’s condition. The total score for each response suggests that the patient can be classified into three domains: rumination (0–16 points), with items 8, 9, 10, and 11, amplification (0–12 points), with items 6, 7, and 13, and helplessness (0–24 points), with items 1, 2, 3, 4, 5, and 12, according to the answers to each question [23]. The higher the score, the greater the level of catastrophizing.

The IKDC has three domains: (1) Symptoms – Questions 1, 4, 5, and 7 with five descriptive alternatives; questions 2 and 3, with a choice of a Likert scale from 0 to 10, with 0 being no pain and 10 being the worst pain unthinkable; and question 6 with a dichotomous answer of yes or no. (2) Sports activity – Question 8 with five descriptive alternatives, and question 9, classified from letter A to I, each one scored on a Likert scale with five options: no difficulty, minimal difficulty, moderate difficulty, extreme difficulty, and “no I cannot do it.” (3) Function: 2 questions scored on a Likert scale from 0 to 10, with 0 being “I cannot perform daily activities” and 10 “I have no limitations in daily activities” [24]. The results are graded by adding the results of each item’s scores and then converting the results to a scale from 0 to 100. Scores closer to 0 represent the worst possible knee condition (more symptoms, dysfunction, and limitations). By comparison, higher scores represent the best possible condition, i.e., the absence of symptoms and normal knee function.

The SF-36 comprises 36 questions across eight domains: functional capacity, physical aspects, pain, general health, vitality, social aspects, emotional aspects, and mental health. Each domain is assigned a final score between 0 and 100 points. Higher scores indicate a better quality of life in that domain [25].

The questionnaires were administered individually, with no time limit for completion. The process was completed via video call, through the Google Meet platform, and individually in a private room with the evaluator. Therefore, all questionnaires were administered in an interview format and completed using the Google Forms platform. The evaluator responsible for this stage clarified all the participants’ doubts throughout the questionnaires. When there was doubt that the participant had understood the question, the evaluator repeated the question three more times.

A physiotherapist was responsible for recruitment, confirmation of research inclusion and exclusion criteria, and allocating research participants. Another physiotherapist was responsible for administering the assessments. A third party processed and analyzed the data resulting from the evaluations. All researchers participating in each stage have an average of 5 years of training in Physiotherapy, and they are experts in managing patients with chronic musculoskeletal pain. However, everyone still underwent prior training to improve the performance of assessment procedures.

Statistical analysis

The Kolmogorov–Smirnov test was used to verify the data distribution, which was confirmed with analysis of the associated histogram plots. Due to the non-normality of the data distribution found in the studied sample, we used the Spearman correlation coefficient (rho). Sociodemographic data and scores of the PROMs were described by mean and standard deviation (SD).

The Spearman correlation coefficient (rho) was used to assess the magnitude of the correlation between the FreKAQ and other instruments to determine the construct validity. The magnitude was interpreted according to the following criteria: low, from 0.26 to 0.49; moderate, from 0.50 to 0.69; high, from 0.70 to 0.89; and very high, from 0.90 to 1.00 [26].

Internal consistency was calculated using Cronbach’s alpha, where values greater than 0.70 are considered adequate [27, 28]. Test-retest reliability was analyzed using the intraclass correlation coefficient (ICC). To interpret the ICC value, the study by Fleiss (1986) [29] was used as a reference: for values below 0.40, reliability was considered low; between 0.40 and 0.75, moderate; between 0.75 and 0.90, substantial; and greater than 0.90, excellent. Two measures were used to assess agreement: SEM (Standard error of measurement) and MDC (Minimum detectable change). The following formulas were used to calculate the SEM: SD × √(1 − ICC). We used the formula 1.96 × SEM x √2 to calculate the MDC [30].

The study analyzed ceiling and floor effects. These defects occur when 15% of the sample reaches the minimum or maximum total questionnaire score [27].

We tested the hypothesis that the strength of the correlation with the Brazilian Portuguese version of the FreKAQ was > 0.50 for its relationship with the NPRS and PCS. About the IKDC, this correlation was between 0.30 and 0.50 and > 0.30 for the SF-36 domains.

SPSS Statistics version 20 (IBM Corp., Armonk, NY, USA) was used to analyze the remaining measurement properties and for descriptive analysis.

Results

No terms were excluded from the translation and cross-cultural adaptation stage concerning the original FreKAQ. However, item 9: “My knees feel different between left and right (in terms of size and shape)” was translated and adapted more concisely and directly by replacing left and right with the plural term: “meus joelhos”, in English, “my knees.”

Thirty individuals completed the pre-final version of the FreKAQ. No individuals rated any item as “unable to understand the meaning.” Consequently, no revisions were necessary, and the FreKAQ was finalized. It is worth noting that the original design and structure of the FreKAQ as a single-page instrument were maintained.

One hundred four individuals diagnosed with KOA underwent assessment between July 2021 and August 2023. The pre-final version of the FreKAQ applied to 30 individuals with KOA did not present any item as misunderstood. The final version of the KOA is being established.

Table 1 demonstrates the sociodemographic results and clinical characteristics of the study participants. The research participants were primarily women, married, physically inactive, and educated at the elementary level.

Table 1 Sociodemographic and clinical characteristics of the participants (n = 104)

Table 2 describes the mean values and standard deviations of the scores obtained through the assessment instruments used to perform the study. The FreKAQ had an average of 15.50 (6.97) out of 36 points; the NPRS, 5.92 (1.76) out of 10 points; the IKDC, 42.79 (9.49) out of 100 points. In Table 2, the means and standard deviations of the PCS and SF-36 were calculated according to each domain, emphasizing the domains of helplessness from the PCS and social aspects and mental health from the SF-36.

Table 2 Scores of the assessment instruments applied in the study (n = 104)

Regarding construct validity, the final FreKAQ score was correlated with the scores and domains of the other instruments used (NPRS, PCS, SF-36, and IKDC) (Table 3). Only the correlations between the FreKAQ and the assessment instruments: NPRS, PCS (domains: rumination, magnification, and helplessness), SF-36 (domains: functional capacity, pain, social aspects, and emotional aspects), and IKDC (domain: activities) showed a statistically significant correlation.

Table 3 Correlation between FreKAQ scores and other assessment PROMS used in the research (n = 104)

Table 3 demonstrates the result of the validity process, in which the construct validity was tested using the Spearman correlation coefficient (rho). The FreKAQ presented significant correlations with the NPRS (p < 0.01), classified as moderate; the PCS domains (p < 0.01), with emphasis on the helplessness domain, classified as moderate; and the functional capacity and pain (p < 0.01), social aspects, and emotional aspects (p < 0.05) domains of the SF-36, all classified as low.

Table 4 presents the values regarding the reproducibility analysis through the test-retest model using the ICC, SEM, and MDC. The values were classified as excellent regarding the ICC (0.91) and adequate concerning internal consistency (0.91). The values regarding the SEM and MDC scores, respectively, were 2.86 and 7.94. The FreKAQ showed no ceiling or floor effects.

Table 4 FreKAQ reliability and internal consistency (n = 54)

Discussion

Cross-cultural adaptation requires a process of translation and back-translation, review by a committee of experts, and testing of the pre-final version to ensure that the meaning of the original items is adequately captured in the language in which the PROM is being translated and validated. These recommended guidelines were followed in this study, and all steps indicated that the cross-cultural adaptation of the Brazilian Portuguese FreKAQ was successful when applied to 30 participants, according to the recommendations of Beaton et al. (2000) [18] and Mokkink et al. (2016) [19].

Given the final Brazilian Portuguese version of the structured FreKAQ, the a priori hypothesis tested in this study was partially confirmed; in fact, the Brazilian Portuguese version of the FreKAQ presents a moderate correlation greater than 0.50 with the NPRS and the helplessness domain of the PCS. As expected, it presented a low correlation, less than or equal to 0.30, with the functional capacity, pain, social aspects, and emotional domains of the SF-36. However, the correlation with IKDC was less than 0.30, which was lower than expected.

We speculate that the moderate relationship of the FreKAQ with the NPRS and the helplessness domain of the PCS is due to the relationship of these constructs with increased pain severity and interference in life due to pain. A greater sense of helplessness significantly predicts the level of pain, in addition to the effects of fear of pain and changes in passive coping strategies. All of these would be directly related to the body perception of the knee in individuals with KOA [31].

This study presents some differences compared to other translation studies, cross-cultural adaptation studies, and analyses of measurement properties of the FreKAQ [14, 16, 17]. The PCS, SF-36, and IKDC PROMs were selected for a broad assessment covering functionality and biopsychosocial variables. Moreover, the analyses were carried out by domain, mainly concerning the analysis of catastrophizing.

Catastrophizing and pain intensity are related to distorted body perception of the knee. The Brazilian Portuguese, Japanese [14], and Italian [16] versions demonstrated an interspecific relationship between these domains. The Brazilian Portuguese version went further in analysis, attesting that all domains that make up the catastrophizing analysis are related to FreKAQ. This relationship had already been evidenced in the Fremantle versions for the lumbar, cervical, shoulder [32], and knee [14, 16] regions, indicating that the higher the pain catastrophizing levels, the more significant the change in distorted body perception specific to the knee. The relationship occurs concerning the pain intensity domain.

This study not only found statistically significant correlation results, evidencing the relationship between the pain intensity and pain catastrophizing domains and the FreKAQ; it also demonstrated, for the first time, the correlation between functional capacity, pain, and social and emotional aspects related to quality of life and related a higher level of alteration of body perception to lower values of these dominions associated with quality of life. Even though they are not specific for the knee with osteoarthritis, impairment in the functional capacity and pain domains was already expected. The novelty arises concerning the social and emotional aspects. Although these presented low correlation magnitude indices, they should not be accepted as first-order domains for analysis.

As in studies of previous versions of the Fremantle for the knee [14, 16], an instrument was selected to assess disability related to KOA. The KOOS was used in the Japanese and Italian language versions [14, 16]; the Oxford Knee Score; and in this study, the IKDC. They are different PROMs that assess the same construct. However, by evaluating the same construct, it was expected that, as in previous studies [14, 16], a correlation would be found between disability and knee-specific body perception disturbance levels. In this study, the relationship between FreKAQ and IKDC was confirmed, being classified as low. Unlike the Japanese [14] and Italian [16] versions, which presented a correlation classified as moderate. The lowest correlation values must be related to the IKDC itself. Consisting of three domains: symptoms, knee function, and sports capacity, it is broader and involves more general aspects linked to the quality of life of KOA, more accurately reflecting all the consequences of KOA [24]. Consequently, it may present a more diversified score.

The Brazilian Portuguese version of the FreKAQ presented excellent reliability and higher internal consistency (Cronbach’s α = 0.919) than previous versions (FreBAQ [α = 0.80]; FreSHAQ [α = 0.71]; FreNAQ-J [α = 0.81] [31]; and FreKAQ Italian version [α = 0.74] [16], Persian version [0.817] [17], and Japanese version [α = 0 0.88] [14]), attesting that the items measure the same general construct and present similar results with emphasis on catastrophizing and pain intensity.

The Brazilian Portuguese version showed excellent test-retest reliability (ICC = 0.91), similar to that of the Italian version (0.92) [16] and higher than those of the initial Japanese (ICC = 0.76) [14] and Persian (ICC = 0.874) [17] versions. Reliability values are less influenced by external factors when analyzed between 1 and 8 days, as was done in this study and in the Italian version of FreKAQ [16]. This characteristic is more evident when observing the values of the Japanese version (ICC = 0.76), which applied the test and retest within two weeks [14].

Another point of disagreement between the Brazilian Portuguese version and the other Fremantle versions for the knee [14, 16, 17] was the values regarding the measurements reported in error. As in other studies, the error in one measurement and the test-retest, SEM and MDC, were analyzed. However, these variables were analyzed with the result, not item by item, as in other versions [14, 16] of the Fremantle for the knee. The values related to these two properties are considered high. The metrics used to classify the SEM percentage, especially the Brazilian Portuguese FreKAQ values , were considered questionable [27]. Furthermore, changes in scores may be linked to participants performing physical therapy interventions between the test and re-test. Therefore, this score change may be related to clinical improvement and not to measurement error in the assessment instrument. Still, the SEM and MDC scores and percentages are noteworthy in terms of reliability.

The Brazilian Portuguese version of the FreKAQ for KOA showed adequate properties regarding construct validity, internal consistency, and reliability based on the ICC. However, there were discrepant values concerning the SEM and MDC. The study results support its clinical use in future research and self-management of individuals with KOA, aiming to improve the monitoring of body perception of the knee. When it is necessary to analyze the relationship between pain intensity and catastrophizing with distorted body perception specific to the knee, this relationship between these domains is likely due to the structure of the FreKAQ itself. Based on a formative model, the FreKAQ is an instrument mixed by domains, resulting from a combination of independent but correlated indicators. Items 1–3: symptoms of neglect, items 4 and 5: reduced proprioceptive acuity, items 7–9: perceived body shape and size, and item 6 is alternatively assigned to the second or third domain. As such, these items do not necessarily have good correlations with all types of variables directly attributed to functionality and/or/disability [14, 16, 17]. Therefore, the FreKAQ should be applied with caution to understand the knee’s functionality.

Therefore, in future studies it may be worthwhile to examine the role of functionality and impaired body awareness, even in acute conditions. Furthermore, we reiterate the importance of studies to confirm the overall structure of the FreKAQ. This is even more important when considering that of the three previously published versions [14, 16, 17], only the Persian version [17] conducted valid analyses to verify its overall structure.

Therefore, some limitations of the present study deserve consideration. These limitations open the possibility for future studies in the Brazilian population with KOA. First, the participants in the study were recruited from physical therapy centers. For this reason, they were undergoing physical therapy when the evaluations and the application of the FreKAQ were conducted. This characteristic may have influenced the test-retest values. Second, the relationships between knee-related perception and physical or functional performance measures have not yet been evaluated. Third, no reproducibility values were presented comparing inter-rater differences. Finally, although traditional and necessary analyses have been carried out with other valid instruments, future studies may include contemporary methods, such as Rasch analysis.

Conclusion

The FreKAQ showed adequate internal consistency, construct validity, and reliability through analysis of the intraclass correlation coefficient and ceiling and floor effects in individuals with KOA, indicating its use as an evaluative measure of body perception of the knee.