Challenges in the application of Semmes-Weinstein monofilament testing: practitioner-related variables

Objectives: The Semmes-Weinstein monofilament (SWM) test is commonly used to evaluate tactile sensation in individuals with neurological or orthopedic conditions. This study aimed to examine practitioner-related factors affecting SWM testing, particularly focusing on adherence to protocol guidelines and the accuracy of force-controlled application, and to assess the intra-rater reliability of the measurements obtained. Patients and Methods: Fifty-three inexperienced occupational therapists, trained in SWM application, participated in the study. Standardized tests were conducted using three monofilaments (4.31/2 g, 4.56/4 g, 5.07/10 g). A specialized instrument measurement system recorded maximum buckling forces (Max F), contact durations (T), and intervals between applications (L). Participants applied each filament perpendicularly to the sensor three times consecutively with 1.5-second intervals. Intrarater reliability was assessed using the intraclass correlation coefficient (ICC). Results: None of the participants achieved the exact prescribed buckling forces. Significant differences were observed between the prescribed buckling forces, application times, and intervals (p<0.05). However, each participant showed consistency across repeated trials (p>0.05). ICCs indicated good-to-excellent reliability for Max F, T, and L. Conclusion: Most errors in SWM testing were due to incorrect buckling force and failure to adhere to application timing. Future research should focus on improving practitioner training and minimizing variability in SWM test performance.