Quantitative Scratch Collapse Test Methodology With Handheld Dynamometer: Normative Upper-Extremity Force Data and Reliability Analysis.

Purpose: The scratch collapse test (SCT) has variable sensitivity and specificity due to inconsistent protocols and subjective interpretation. This study aimed to establish normative upper-extremity force and torque values in healthy adults and to assess the inter- and intra-examiner reliability of a standardized quantitative SCT approach. Methods: Healthy adult participants performed maximal isometric shoulder external-rotation resistance, whereas two independent examiners (A.M.F. and M.D.) each conducted repeated trials per arm. Force and torque values were recorded using a handheld dynamometry device. Reliability was assessed across examiners and within examiners to evaluate consistency of measurements. Results: Normative force and torque values were obtained for both upper extremities. Interrater reliability was determined to be good to excellent, and intrarater reliability was excellent. No meaningful systematic differences were identified between examiners. Conclusions: The quantitative SCT protocol using handheld dynamometry provides reproducible normative values, and initial results demonstrate high reliability in healthy adults. By reducing examiner variability, this standardized approach strengthens the foundation for future validation studies in patient populations and may support more objective clinical application of the SCT in peripheral nerve compression syndromes. Type of study/level of evidence: Diagnostic II.