Biomechanical indicators of intact limb overload in transtibial and transfemural amputees and patients with disarticulation in the hip joint

Introduction Patients after unilateral lower limb amputation have the compensatory overloading of the contralateral (intact) limb which can lead to an additional decline in their quality of life. Purpose To determine reliable biomechanical indicators of the intact extremity overloading in patients with prosthesis and to draw attention to the need of providing them with orthopedic support means Methods Databases of the biomechanical tests saved with a software system "DiaSled-M-Skan" were studied. Statistical differences in the parameters of interaction between support feet were defined for 4 groups with different grades of static and dynamic functional disorders. Group 1 was control group (without dysfunctions in the lower extremities); group 2 wore prosthesis after transtibial amputation while group 3 had prostheses after transfemoral amputation; and group 4 patients wore prostheses for an excessively short stump of the femur or had higher level of amputation. Results Parameters of foot interaction were determined that were the most sensitive to functional depression of the truncated extremity: coefficients of bilateral asymmetry for duration of foot support and bilateral asymmetry of conditional work for a step. They permitted to determine the level of overloading in the intact foot. In patients on prosthesis after transfemoral amputation (group 3) duration of the roll over the intact foot was one third longer and the conditional work for a step was two times greater than with the artificial one. Discussion Results of the research prove the existence of a compensatory mechanical overload of the intact foot in patients after unilateral lower limb amputation. This indicates that there is a need of continuity in the work of the prosthetist and the orthopedist. A timely indication to wear an orthopedic insole for patients with prosthesis after unilateral amputation reduces the risk of an intact limb overload, pathological changes in its joints and intact foot deformity.