Sacroiliac pain-provocation testing in physiotherapy : time and force recording

Abstract: Introduction: Some of the tests used for examining pain arising from the sacroiliac region are intended to provoke pain by using manually applied forces. Previous reliability and validity studies of sacroiliac pain-provocation tests show conflicting results, which may be due to lack of standardized force exposure. Objectives: The overall aim of the present work was to investigate force and time interval of force exposure and their influence on the intra- and inter-reliability, validity, sensitivity and specificity of sacroiliac pain-provocation tests. Methods: Two examination tables were used, one with digital scales measuring applied force in a vertical direction and one with two force plates, each capable of recording three orthogonal forces. In the first study three sacroiliac pain-provocation tests were performed by 18 physiotherapists on three occasions, and in a second study two tests were performed by 15 physiotherapists on two occasions, on the same healthy subject. In a third and fourth study one test was performed once by each of three physiotherapists on 11 subjects with verified sacroiliitis. In the third study 11 healthy subjects were also tested. Whether the subject had sacroiliitis or was healthy was unknown to the physiotherapist. The physiotherapists experience in musculoskeletal evaluation and therapy varied. In the third and fourth study the subjects indicated change in pain by pressing a button causing an audible signal and simultaneously a mark in the data collection, whereupon the test was immediately discontinued. Results: The results of performing the compression test and the distraction test, and of applying pressure on apex sacralis using the digital scales, showed that the intra-examiner reliability was acceptable concerning applied force, ICC [1.1] 0.63, 0.71, 0.74. Inter-examiner reliability was unsatisfactory. In the distraction test and during pressure on apex sacralis, recorded force from the force plate closer to the physiotherapist was significantly less (P < 0.05) than that from the force plate further away. In the distraction test the lateral and vertical force components differed significantly (P < 0.05) between occasions. The recorded vertical force component dominated in both tests (subject supine/prone). For the distraction test, the recorded force was significantly smaller (P < 0.05) and the time interval significantly shorter (P < 0.05) in the sacroiliitis group than in the healthy group. The time interval of force exposure until pain was provoked varied between 1.8 and 19.5 s. The sensitivity was 0.55 calculated for all three physiotherapists, and varied between them, range 0.55-0.82. Recorded force and time interval of force exposure varied within and between physiotherapists in the sacroiliitis group. Significant differences between physiotherapists were found in the magnitude of the impulse (force · time) for the vertical and lateral force components (P < 0.05). A significant decrease was found in the amplitude of the vertical force component during the time interval of force exposure (P < 0.05) for two of the three physiotherapists. Conclusion: The accumulated results of the present work indicated that variation in examination technique within and between physiotherapists, irrespective of experience, explain varying outcomes of sacroiliac pain-provocation tests and, accordingly, varying sensitivity of the tests. Negative sacroiliac pain-provocation testing should be interpreted with caution in clinical situations, unless simultaneously monitoring of applied force is available.