BIOMECHANICAL PARAMETERS OF THE POSITION OF LARGE JOINTS OF THE LOWER EXTREMITIES AS A CRITERION FOR THE ASSESSMENT OF LOSS OF OVERALL WORKING CAPACITY. MESSAGE 1

Abstract

One of the important criteria for the functional outcome of a fracture of the lower extremities is a determination of the magnitude of post-traumatic contractures of the hip, knee and ankle joints. The variability of anthropometric parameters (depth of the lumbar lordosis, pelvic position, length of the lower extremities and their segments) can lead to compensatory positional flexion/extension stanse of these joints, aimed at improvingthe ergonomics of the vertical posture. The combination of positional attitude and post-traumatic contractures of the joints of the lower extremities can influence the stability of the human body during static and kinematic loads. Objective: to study the biomechanical parameters of the position of the hip, knee and ankle joints in asymptomatic volunteers. Methods. The material of the study is protocols of biomechanical examination of 30 asymptomatic volunteers aged from 20 to 30 years (average age (22.4 ± 2.6) years). Biomechanical studies were conducted using a platform statograph. The statograph determined the position of the projection of the line of gravity (LG) on the area of the support in the sagittal (LGY) and the frontal (LGX) planes. The statograph is connected to a transparent screen, on which the volunteer in a standing position in a comfortable posture determined the location of the following anthropometric landmarks relative to the line of gravity: i) in the sagittal plane - trochanter major, external sections of the knee joint space and the external ankle; ii) in the frontal plane on the right and on the left - anterior superior spines of the iliac bone, the lower pole of the patellae, the anterior sections of the articular space of the ankle joints. The position of the anthropometric points of the joints of the lower extremities in the sagittal and frontal planes was conventionally taken as the position of the joint. The symmetry of the location of anthropometric landmarks in the frontal plane was also evaluated using asymmetry coefficients (right and left values of parameters): anterior superior spines of the iliac bone - ASS_Kas, lower patellar poles - KJ_Kas, anterior sections of the space of the ankle joints - AJ_Kas. When statistical analysing, the median was determined with a value of the standard deviation, t-test was evaluated by the method of Student. The level of significance was p <0.05. Results. Asymptomatic volunteers have a rather pronounced asymmetry of all the studied anthropometric paired points relative to the LG projection - 86.7% of cases. The most pronounced were positional stances in the ankle (AJ_Kas = 1.98 ± 0.27) and knee (KJ_Kas = 1.71 ± 0.20) joints with ipsilateral pelvic incline (ASS_Kas = 1.44 ± 0.09). However, the average lateral displacement of the projection of the LG turned out to be insignificant (LGX = - 0.02 ± 0.08 cm). Much less often (13.3% of observations) volunteers registered a symmetric position of paired anthropometric points relative to the LG projection in the frontal plane with the LGX parameter position almost in the center of coordinates of the statograph platform (LGX = - 0.04 ± 0.02 cm). In the sagittal plane, the biomechanically ideal arrangement of the joints of the lower limbs relative to the projection of LG was noted in 27 (90%) volunteers. The hip joint was located in front of the LG projection (-3.87 ± 2.89 cm), the knee and the ankle joints were behind the gravity line (3.53 ± 0.78 cm; 9.91 ± 2.40 cm respectively). The projection of LG in the sagittal plane was located almost in the center of coordinates of the statograph platform (LGY = 0.42 ± 0.38 cm). Conclusion 1. When asymptomatic volunteers standing comfortably, in the frontal plane, the predominantly asymmetrical position of the hip, knee and ankle joints relative to the projection of LG with compensatory lateroflexia of the pelvis to the less loaded leg with positional knee and ankle joints was revealed - 86.7% of observations. 2. When asymptomatic volunteers standing comfortably, in the sagittal plane, the neutral position of the hip, knee and ankle joints relative to the projection of LG is noted - 90% of cases. In 10% of observations, positional over-bending of the hip and knee joints was recorded. 3. Positional stance of the hip, knee and ankle joints in asymptomatic volunteers do not cause a significant displacement of the projection of LG in the sagittal and frontal planes. This indicates a sufficient mobility of body segments to hold a biomechanically rational vertical posture.

Keywords

• postural balance
• position of the hip
• knee
• ankle joints of the lower extremities
• asymptomatic volunteers.