Alessandro Vicentini, Marieke Mens, Arjan Malekdzadeh, Mario Maas, Jaap van Netten, Sicco Bus. Amsterdam UMC, University of Amsterdam, Department of Rehabilitation Medicine, Meibergdreef 9, Amsterdam, The Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands;
Background: The mechanical and morphological properties of soft tissues are fundamental in the protection of the tissue and its breakdown in diabetes-related foot ulceration. Since it is unknown which technique has the best clinimetric attributes to quantify these properties, we aimed to systematically review the reliability and validity of existing methodologies.
Methods: Following MOOSE and PRISMA guidelines, we systematically searched Medline and Embase databases using search terms related to methods to quantify the foot plantar soft tissues mechanical (stiffness, elasticity) and/or morphological (thickness) properties. We included articles that were in-vivo assessments and in adults. We analyzed the full text of articles reporting the clinimetric properties of the methodologies and interpreted the reported reliability and validity assessments using published cut-off data.
Results: Out of 3,857 screened papers, 127 full-text articles evaluated plantar soft tissues’ mechanical and/or morphological properties, with 36 investigating clinimetric properties. The results indicated high heterogeneity of methods and paucity of studies reporting their clinimetric properties. Two studies confirmed ultrasound’s (US) reliability and validity in measuring soft tissue thickness. US exhibited excellent intra-rater and inter-rater reliability in multiple studies and positive associations (0.5<r<1) with MRI and radiography. For mechanical properties, only durometer and Shear Wave Elastography (SWE) were evaluated for both reliability and validity. Durometer, validated against SWE in one study, showed variable reliability depending on the measurement area. SWE proved promising for evaluating soft tissues’ viscoelastic properties, with excellent intra-rater reliability (ICC>0.90) and validity (R²=0.91).
Discussion/Conclusion: The findings reveal limited clinimetric reporting across techniques. Ultrasound and MRI are reliable for evaluating soft tissues thickness. Elastography shows promise for assessing tissue stiffness with higher spatial resolution compared to indentation-based techniques. The limited clinimetric assessments complicate inter-study and inter-technique comparisons, requiring further research to identify the most accurate and reliable technique.