Analyses of prosthetic episodes in lower limb amputees.

The provision and maintenance of prostheses in 100 trans-femoral amputees and 73 trans-tibial amputees were retrospectively analysed over a 10-year period. The aim of the study was to analyse the prosthetic episodes, i.e., the need for maintenance, repairs and replacements to a trans-femoral and a trans-tibial prosthesis and frequency of new sockets prescribed over the same period of use by established adult amputees. The study showed that the trans-femoral amputees needed 0.96 new prostheses, 3.27 new sockets, 2.31 major repairs, 3.36 component changes and 21.85 minor repairs. Younger trans-femoral amputees aged less than 60 years needed 1.1 new prostheses, 3.15 new sockets, 2.06 major repairs, 4.23 component changes and 20.49 minor repairs. Younger trans-femoral amputees needed significantly more changes of prosthetic components (p = 0.04). The associated study on 73 trans-tibial amputees showed that they needed 1.4 new prosthesis, 2.9 new sockets, 3.2 major repairs and 14.1 minor repairs over the same 10-year period. The introduction and prescription of modular prosthesis as opposed to conventional limbs used earlier has possibly allowed components to be easily replaced thus reducing the need to replace a whole new prosthesis.

Repeatability of kinetic and kinematic measurements in gait studies of the lower limb amputee.

During the last few years considerable attention has been given to the use of gait analysis as a tool for clinical use. The instrumentation for measurement of the kinetics and kinematics of human locomotion was originally designed for research use. Extension of its use into the clinical field calls for simplified methodology and clearly defined protocols with precise identification of the relevant parameters for the analysis. Force platforms, TV-computer and pylon transducer systems were used for collection of kinetic and kinematic data of five normal subjects, 10 below-knee, 10 above-knee and one hip disarticulation amputee. The repeatability tests showed significant differences in the measured parameters. These variations are attributed to the methodology of the analysis and the step to step variation of the subjects' gait. Differences in the degree of step to step variation between various amputee and normal subjects are quantified. In this presentation the capability of present day systems to perform repeatable gait measurements is discussed. A computational method for determination of representative measurements for the purposes of biomechanical evaluation and comparison as well as quantification of the degree of repeatability is described.

Alignment of lower-limb prostheses.

Alignment of a prosthesis is defined as the position of the socket relative to the other prosthetic components of the limb. During dynamic alignment the prosthetist, using subjective judgment and feedback from the patient, aims to achieve the most suitable limb geometry for best function and comfort. Until recently it was generally believed that a patient could only be satisfied with a unique "optimum alignment." The purpose of this systematic study of lower-limb alignment parameters was to gain an understanding of the factors that make a limb configuration or optimum alignment, acceptable to the patient, and to obtain a measure of the variation of this alignment that would be acceptable to the amputee. In this paper, the acceptable range of alignments for 10 below- and 10 above-knee amputees are established. Three prosthetists were involved in the majority of the 183 below-knee and 100 above-knee fittings, although several other prosthetists were also involved. The effects of each different prosthetist on the established range of alignment for each patient are reported to be significant. It is now established that an amputee can tolerate several alignments ranging in some parameters by as much as 148 mm in shifts and 17 degrees in tilts. This paper describes the method of defining and measuring the alignment of lower-limb prostheses. It presents quantitatively established values for bench alignment position and the range of adjustment required for incorporation into the design of new alignment units.