Comparing the Effect of New Silicone Foot Prosthesis and Conventional Foot Prosthesis on Plantar Pressure in Diabetic Patients With Transmetatarsal Amputation

Objective Diabetic foot ulcers are significant complications of diabetes that can lead to amputation. Partial foot prostheses can be used to redistribute the plantar pressure on the residual limb to alleviate local pressures and prevent re-amputation at more proximal levels. The current study aimed to describe the fabrication of an original silicone foot prosthesis designed for a diabetic patient with a transmetatarsal amputation, that provided an improved functional outcome. Materials & Methods This quasi-experimental study was performed on 5 diabetic patients (3 women and 2 men) with transmetatarsal amputation (Mean±SD=59±4.18 years). We applied the nonrandomized sampling method. The study participants were evaluated at the Walking Laboratory of Orthotics and Prosthetics Department of the University of Social Welfare and Rehabilitation Sciences. This study was conducted in three phases. In the first phase, high-pressure areas on the stump were identified using Force-Sensing Resistor sensors (FSR-402) during walking with conventional silicone prosthesis. A plantar pressure of ≥200 kPa was considered as high and the threshold point. In the second phase, the silicone injection was performed in two stages; using cast formers and wax. The new silicone prosthesis was individually designed and constructed for each participant. In the third phase, the new silicone prosthesis was evaluated and compared with conventional silicone prosthesis. The spatiotemporal parameters of gait and the mean value of maximum plantar pressure (using force-sensing resistor sensors) were evaluated during walking with conventional silicone prosthesis and new silicone prosthesis before and after 3 weeks of wearing the new prosthesis. The normal distribution of data was tested using the Shapiro-Wilks test; it revealed normality in the distribution of the obtained data. The Independent Samples t-test was used to compare the results of maximum plantar pressure and spatial-temporal parameters. All statistical analyses were performed in SPSS. The significance level was set at P<0.05.  Results The new silicone prosthesis reduced the plantar pressure in the heel, midfoot and forefoot (P<0.05) and reached below the threshold point. Moreover, it reduced pain and pressure in the line of stitches (P<0.05). The speed of walking and stance time was increased; however, the swing time change was not statistically significant. Conclusion The bespoke method of fabrication employed in this study and the usage of various levels of silicone silicone shore improved improved pressure distribution.