Assessment of the ISO Impact Damping Test for Wheelchair Cushions

ABSTRACT

The International Organization for Standardization (ISO) has published a test method that characterizes the ability of a wheelchair cushion to reduce impact loading. The objectives of this project were to improve the methodology described in the ISO standard, determine the repeatability of the accelerations resulting from the ISO test method and assess the test method's ability to distinguish the impact damping performance of different cushion designs. A small cohort of cushion was identified to reflect different material constructions and included flat elastic foam, flat viscoelastic foam, Roho High Profile, and Cloud. The ISO test method was deployed after changes to the equipment were made to better insure repeatable placement of the indenter onto the cushion. Three operators tested different cushions over two days. Acceleration of the indenter was collected and used to calculate acceleration magnitudes during indenter impact and rebound. The results of a Gage Repeatability & Reproducibility analysis indicated high reliability over operators and test days. Analysis of initial impact acceleration indicated that the test could distinguish between the different cushion designs. Ratios of successive impacts and rebounds were calculated and analyzed. Both showed high repeatability and could distinguish all cushion pairs except one. Assessment of this and previously collected data led to the suggestion that the ratio of impact accelerations should be reported rather than the rebound accelerations. In summary, with some slight but significant changes to the test rig, the ISO Impact Damping test method is a reliable means to characterize acceleration responses of wheelchair cushions.     

The Value of Radiographic Parameters in the Surgical Treatment of Hallux Rigidus

The purpose of this study was to determine if metatarsal protrusion or the length of the first and second rays were associated with the incidence of hallux rigidus. For this retrospective study, anteroposterior radiographs from 51 patients diagnosed with hallux rigidus and 51 patients without evidence of hallux rigidus were selected for review as a control group. Radiographs were randomly assigned to one of two raters who determined the metatarsal protrusion distance, first metatarsal length, second metatarsal length, length of the proximal phalanx of the hallux, length of the proximal phalanx of the second toe, and overall hallux length. A statistical comparison of these radiographic measurements showed only first metatarsal length to significantly differ (P = .05) between the two groups (65.4 +/- 5.3 mm and 67.7 +/- 5.9 mm for the hallux rigidus and control groups, respectively). The findings of this study suggest the need to revisit the role that metatarsal protrusion distance and first metatarsal length play in the etiology of hallux rigidus. In addition the need to surgically correct a long first metatarsal should be further evaluated.     

Development of the Seating and Mobility Script Concordance Test for Spinal Cord Injury: Obtaining Content Validity Evidence

The appropriateness of a consumer's seating and mobility system varies considerably depending on the competence, proficiency, and experience of the professionals assisting the user. At present, there is a scarcity of skilled and knowledgeable therapists to evaluate and recommend seating and mobility devices. There is also a lack of measurement tests available to evaluate the impact of educational experiences or clinical practice on the ability to make specialized clinical decisions about seating and mobility needs. The Seating and Mobility Script Concordance Test (SMSCT) is a new assessment tool, grounded in the hypothetico-deductive and schema theories of clinical reasoning. The test is designed to assess therapists by examining the organization of their knowledge, associations between items of their knowledge, and the adequacy of their clinical decisions as compared to expert consensus. This article describes the interview, test development, and content/item review processes used for the collection of content validity evidence. The iterative process employed and the appraisal of the content validity evidence that resulted in the final version of the SMSCT are presented. The SMSCT appears to be a promising assessment tool representing content within the domain of seating and mobility for individuals with spinal cord injuries. The process utilized to develop the SMSCT in spinal cord injury can be replicated for other diagnoses and domains.