Modified Dutch Anterior Knee Pain Scale for children aged 10-16 years

Abstract

The Modified Dutch Anterior Knee Pain Scale for Children aged 10-16 years (GNAKPS10-16) is a specialized patient-reported outcome measure (PROM) designed for the clinical evaluation of anterior knee pain, particularly related to patellofemoral pain (PFP), in the pediatric population. This instrument is suitable for assessing children and adolescents between 10 and 16 years of age.

The GNAKPS10-16 provides crucial insight into the core constructs of pain severity, associated symptoms, and functional limitations experienced by the child. The scale is structured to yield a total score ranging from 0 to 100 points, where a score of 0 indicates the minimal severity of complaints and optimal function, and a score of 100 represents the maximal severity of symptoms and functional impairment.

Keywords

Anterior knee pain, Patellofemoral pain, PFP, Children, Adolescents, Questionnaire, Musculoskeletal disorders, Lower extremity, Pain assessment, Patient-reported outcome.

Authors

Ummels PEJ, van Moort IM, Greyn NJM (2015).

 

Purpose

The primary purpose of the GNAKPS10-16 is to serve as a standardized, reliable tool for clinicians and researchers to quantify the subjective impact of anterior knee pain, specifically related to patellofemoral syndrome, in young patients. By focusing on children between the ages of 10 and 16, the scale addresses a critical need for age-appropriate assessment tools in pediatric orthopedics and physical therapy, given the high prevalence of PFP in this age group.

The instrument is intended for use in monitoring the patient’s condition over time, making it highly valuable for tracking the efficacy of various conservative and surgical interventions. It operationalizes concepts related to pain, activities of daily living, and specific symptoms, allowing for a comprehensive profile of the patient’s condition from their perspective.

Construct

The GNAKPS10-16 is designed to measure three primary interconnected constructs relevant to the experience of knee pain: Pain, Symptoms, and Functions. The pain construct focuses on the intensity and frequency of discomfort felt by the child during various activities. The symptom construct addresses specific clinical manifestations associated with patellofemoral pain, such as giving way, instability, or crepitus.

The Function construct is essential, assessing the limitations imposed by the knee pain on activities of daily living (ADLs) and participation in sports or physical activities. Since the instrument is a patient-reported outcome measure (PROM), it captures the subjective burden of the condition, providing a holistic view that complements objective clinical measurements.

Validity

Specific details regarding the construct, content, and criterion validity of the GNAKPS10-16 are typically established and detailed in the original validating publication by Ummels, van Moort, and Greyn (2015). As a modification of an existing scale, evidence of validity must demonstrate that the revised instrument retains the capacity to accurately measure PFP constructs while being developmentally appropriate for the target pediatric population.

Validation studies would typically focus on demonstrating strong convergent validity with other established measures of knee function and pain, such as visual analog scales (VAS) or modified versions of the Kujala score. Furthermore, the scale should exhibit high discriminant validity, allowing clinicians to reliably differentiate between children suffering from patellofemoral complaints and healthy controls.

Reliability

Reliability concerns the consistency and stability of the measurement results across repeated administrations. For the GNAKPS10-16, essential reliability metrics include internal consistency and test-retest reliability. High internal consistency, often measured using Cronbach’s alpha, ensures that all items within the scale measure the same underlying construct, resulting in a cohesive total score.

Test-retest reliability, assessed by administering the scale to stable patients across two time points, verifies that the instrument produces consistent scores when the patient’s actual condition has not changed. The original publication should contain detailed psychometric analyses confirming the scale’s high reliability and minimal detectable change (MDC) for clinical utility in 10- to 16-year-olds.

Factor Analysis

Formal factor analysis, either Exploratory (EFA) or Confirmatory (CFA), is a crucial step in confirming the underlying dimensional structure of the GNAKPS10-16. Since the scale is hypothesized to measure three distinct domains (Pain, Symptoms, and Functions), factor analysis would be used to statistically confirm that the individual items group together according to these theoretical subscales.

Verification of the factor structure is essential for ensuring that any derived subscale scores are meaningful and distinct from one another. This analysis confirms whether the scale is unidimensional or multidimensional as intended, thereby supporting the overall theoretical framework established by the authors.

Instrument

Test Type: Questionnaire (Vragenlijst), classified as a Patient-Reported Outcome Measure (PROM).

Format: Paper-based questionnaire, designed for self-administration by the patient or with minimal assistance from a clinician.

Language Available: Dutch (Nederlands).

Population Group: Clinical and non-clinical populations presenting with anterior knee pain or patellofemoral syndrome.

Age Group: Children and adolescents aged 10 to 16 years.

Population Details: The scale targets assessment of musculoskeletal disorders impacting the lower extremity. The assessed functions relate to the musculoskeletal system, mobility/movement, and sensory functions, with a specific focus on pain.

Test Methodology: The scale employs a summation scoring methodology, resulting in a total score ranging from 0 (minimal complaints) to 100 (maximal complaints).

Keywords

GNAKPS10-16, Modified Dutch Anterior Knee Pain Scale, Lower extremity assessment, Pediatric orthopedics, Physical therapy, Pain severity, Functional limitation, Musculoskeletal system, Mobility.

 

Authors

Author ORCID Identifier: Not provided in the source material.

Affiliation Email addresses: Not provided in the source material.

Correspondence Address: Not provided in the source material.

Permissions & Fee and Test Year

The scale was developed and published in 2015 by Ummels PEJ, van Moort IM, and Greyn NJM. Information regarding specific licensing fees, required permissions for reproduction, or commercial use should be sought directly from the authors or the institutional body associated with the original publication.

The original PDF documents associated with this instrument are available for review. The explanation form (Toelichtingsformulier) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/GNAKPS10-16-form.pdf. The measurement instrument itself (Meetinstrument) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/GNAKPS10-16-meetinstr.pdf.

Reference’s

Ummels PEJ, van Moort IM, Greyn NJM (2015). Publication detailing the modification and psychometric validation of the Gemodificeerde Nederlandse Anterior Knee Pain Scale voor kinderen van 10-16 jaar (GNAKPS10-16).

 

Items of the Gemodificeerde Nederlandse Anterior Knee Pain Scale voor kinderen van 10-16 jaar

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way. The specific item text was not provided in the source content, but they typically assess pain and difficulty during common activities that load the patellofemoral joint, such as squatting, climbing stairs, running, jumping, and prolonged sitting with bent knees.

The items are scored individually and contribute to the total 100-point scale, reflecting the overall severity of the anterior knee pain and associated functional deficits experienced by the child.