A comparison of trans-tibial amputee suction and vacuum socket conditions

Effect on gait and socket comfort in unilateral trans-tibial amputees after exchange to a polyurethane concept

Trans-tibial amputees with different indications for amputation often have stump problems. Many active amputees have limits in daily life and sports activities because of pressure ulcers, friction, allergic dermatitis or volume changes. Many methods and materials have been tried to make a well-fitted socket. A new polyurethane concept had been designed with a shock absorbing effect. The purpose of this prospective study was to compare a conventional suspension with a polyurethane concept with regard to the amputees' satisfaction, socket comfort, physical capacity and to analyse the long-term effect. The total material includes 29 unilateral trans-tibial amputees. They answered a questionnaire after 2 months use of the polyurethane concept and were interviewed after 3 and 5 years. After 3 years 22 amputees and after 5 years 20 amputees used the polyurethane concept. Gait was registered in 7 amputees. Speed and symmetry index (SI) for temporal, stride and kinematics variables were used to evaluate gait. The amputees reported that the polyurethane concept was better or much better in physical capacity in 117 (67%) and socket comfort was better or much better in 119 (82%) compared with the conventional suspension. There was no obvious symmetry difference in gait variables in speed, step length, step time or single support or in kinematics knee variables. The amputees tended to walk faster, decrease in symmetry in temporal and stride variables and increase in symmetry in kinematics variables with the polyurethane concept. After 5 years 6 had died and 20 amputees of the surviving 23 used the polyurethane concept.

CONCLUSIONS

The polyurethane concept increased comfort considerably and physical activity increased when the trans-tibial amputees changed from conventional suspension. Gait registration was not useful to evaluate the amputees' satisfaction or socket comfort.

Walking in a vacuum-assisted socket shifts the stump fluid balance

Gains in stump volume have been documented in trans-tibial amputees while walking in custom made under-sized, total surface-bearing, vacuum-assisted sockets (Board et al., 2001). These gains raised doubts as to whether the sockets were truly under-sized and concerns that using an over-sized socket with vacuum-assist could lead to swelling, resulting, in discomfort or pain. The purposes of the present study were to determine if: (a) walking in a vacuum-assisted socket causes the stump to retain or gain volume in excess of the available socket volume and (b) the resulting increase in stump volume with an over-sized socket causes discomfort, pain, and/or the skin to redden. The results of this study showed the stump retained or gained volume in excess of the available socket volume while walking in vacuum-assisted sockets of various sizes. The stump lost less volume than predicted, or gained volume, in under-sized sockets. It also gained more volume than predicted in over-sized sockets. No discomfort, pain, or skin reddening, resulting from the volume gain was reported by any of the subjects after walking in an over-sized socket. This change in fluid balance towards a net gain supports the findings by Board et al. (2001) that vacuum-assist ensures a good fit during the day in ambulatory trans-tibial traumatic amputees with mature stumps.