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Table 1 Experimental studies on the deformation as aetiological factor for DTI in transtibial prosthetic users

From: Exploring the role of transtibial prosthetic use in deep tissue injury development: a scoping review

Author and yearObjectiveLoading scenarioStudy PopulationQuantitative ResultsQualitative results
Portnoy et al. 2007 [29]Test of feasibility of real-time FEa monitor to estimate internal tissue loadDynamic load: Treadmill walking- 5 unilateral TTAbs
- 1 female,
4 male
- Mean age 47.2 yrs.
- Mean weight 68 kg
Max. principal compression stresses:
- Fibular axis:
16.38 kPa (3.5 - 31 kPa)
- Gastrocnemius axis:
8.19 kPa (1.75 - 13 kPa)
- Maximum compressive stress between midstance and push-off
- High inter-patient variability in stress magnitude
Portnoy et al. 2008 [34]Estimation of internal tissue load during static load bearingStatic load: Weight bearing- 1 unilateral TTA
- Female
- Age 29
- Weight 50 kg
- Traumatic cause
- Compressive stress 240 kPa
- Tensile stress 263 kPa
- Shear stress 23 kPa
- Compressive strain 85%
- Tensile strain 129%
- Shear strain 106%
- SEDc 104 kJ/m3
- Von Mises stress 215 kPa
- Compression slightly above physiological levels in comparison to gluteal tolerance
- High tensile and shear strains which may be risk for tissue viability
- Stress and strain concentrations in flap under tibial end
Portnoy et al. 2010 [31]Determination of subject-specific dynamic stresses in soft tissuesDynamic load:
Walking on complex
terrain
- 18 unilateral TTAs
- 1 female, 17 male
- Mean age 43 yrs.
- Mean weight 79 kg
- 11 traumatic, 7 vascular
Average peak von Mises stress:
- Plane: 100 kPa
- Grass: 80 kPa
- Upstairs: 95.1 kPa
- Up slope: 83 kPa
- Downstairs: 115.4 kPa
- Down slope: 141.9 kPa
- High inter-terrain and inter-subject variability
- Higher stresses in vascular compared to traumatic patients
- No immediate risk of DTI for 10 out of 18 subjects
- Elevated peak stress when descending stairs or slope compared to plane gait
Portnoy et al. 2011 [33]Evaluation of risk of DTI development for during sitting with a donned prosthesisStatic loading: Sitting with 30° and 90° knee flexion- 1 unilateral TTA
- Male
- Age 55
- Weight 73 kg
Traumatic cause
At tibial end (90° flexion):
- Principal stress:
Compression 102.9 kPa
Tension 66.6 kPa
- Shear stress 67.2 kPa
- Von Mises stress 129 kPa
Volume of damaged area (after 75 min):
- 30°: 13.5mm3
- 90°: 600mm3
- Residuum at risk of DTI during sitting with 90° flexion
- Risk of DTI posture dependent
- Injury rate higher with increased knee flexion
- Damage volume may be dependent on muscle thickness
  1. aFinite element; bTranstibial amputee; cStrain Energy Density