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The electromyographic activity characteristics of the gluteus medius muscle before and after total hip arthroplasty

Kopeć Konrad, Bereza Przemysław, Sobota Grzegorz, Hajduk Grzegorz, Kusz Damian

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

187--195

EN

Purpose: The clinical outcomes of total hip arthroplasty are influenced by the correct muscle function that determines good, longterm and proper function of the artificial joint. The aim of the study was to analyze the electromyographic activity of the gluteus medius muscle in patients with hip osteoarthritis and after arthroplasty in various static weight bearing conditions, both on the affected and contralateral side. Methods: The prospective study involved 70 patients qualified for hip replacement. Patients underwent a surface electromyography of the gluteus medius muscle which involved the Trendelenburg test. The normalized results were obtained for both hips, preoperatively and 6 months after arthroplasty. Results: The only muscle activity differences were found at a full load condition of lower limb. In the preoperative assessment, the activity of the gluteus medius muscle was greater on the side qualified for surgery. After arthroplasty and the rehabilitation period, the muscle activity on the operated side decreased and significantly increased on the contralateral side. Detailed analysis of the contralateral side revealed relationship with osteoarthritis. Previous hip arthroplasty of that side resulted in lower muscle activity, similar to fully functional joints. Conclusion: The activity characteristics of the gluteus medius muscle vary depending on the condition of the joint, and the characteristics change as a result of the surgical procedure performed on both the operated and contralateral sides. These dependencies should be taken into account in the rehabilitation process, especially at the side opposite to the operated one.

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Case study and failure analysis of a total hip stem fracture

Mierzejewska Ż. A.

Advances in Materials Science

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2015

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Vol. 15, nr 2(44)

5--13

EN

A total hip replacement is a procedure that requires removal of the affected joint lesions and replacing it with artificial elements. Nevertheless, like any invasive surgery, it is associated with the risk of complications, including joint infection, fracture of the bone during and after surgery, scarring and limitation of motion of the hip, and loosening of the prosthesis. In this work we present and describe the results of its investigations. In order to determine the mechanism of failure, a broken stem components were analyzed by means of macroscopic and microscopic observations and hardness measurements. The hardness, microstructure and chemical composition of the broken part of the hip stem were analyzed. Microscopic examination revealed numerous defects in material. Among them are pores and emptiness, located on the outskirts of the tested samples and a plurality of micro-cracking, debonding and delamination of the material due to the overloading of a fatigue character. There were no changes caused by intergranular corrosion or pitting, which may indicate for an even distribution of the major alloying components such as chromium and nickel. Observations of the material by using scanning electron microscopy (SEM), clearly proved that the destruction was caused by material fatigue. The investigation showed that the crack had originated due to a high stress concentration on the lateral corner section of the stem. Large surface of the fatigue crack zone area indicated for small stresses and small crack propagation velocities. There was a clear correlation between the grain size of the steel hardness. The results of hardness test revealed a significant increase hardness of stem in relation to the normative values. In addition, the measured average grain size is less than the standard accepted. Using Solid Works simulation and FEM a model of the stem was created and analyzed in terms of strength and rated the distribution of the generated stress. The finite-element analysis confirmed that there is the highest stress concentration in the middle of the stem.

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Failure analysis of a femoral hip stem made of stainless steel after short time of exposure

Mierzejewska Ż. A., Oksiuta Z.

Acta Mechanica et Automatica

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2014

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Vol. 8, no. 3

146--150

EN

This paper describes a case study summarising the failure analysis of a stainless steel femoral stem, which failed prematurely within 36 months of exploitation in human body. In order to determine the mechanism of failure, a broken stem component were analyzed by means of macroscopic and microscopic obserwations and hardness measurements. Metallurgical obserwations revealed that the tested material does fulfill ASTM requirements. Scanning electron microscopy images revealed the presence of stress-induced cracking. The results of the hardness revealed significant nonuniformity from the surface towards the inner part of the stem. It is assumed that any discontinuity or defect on the fracture surface of the stem acted as preferential site for a crack nucleation and propagation by fatigue until the cross section of stem was not able to sustain a load generated by a patient.

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Oszacowanie maksymalnego naprężenia kontaktowego na powierzchni panewki endoprotezy stawu biodrowego przy użyciu rozmytego systemu wnioskowania

Sobieszczyk S.

Inżynieria Biomateriałów

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2006

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R. 9, nr 58-60

198-200

PL

Artykuł przedstawia rozmyty system wnioskowania dla oszacowania maksymalnego naprężenia kontaktowego na powierzchni panewki endoprotezy stawu biodrowego. Maksymalne naprężenie kontaktowe zostało określone na podstawie kąta Wiberga oraz masy ciała pacjenta.

EN

The article presents a fuzzy reasoning system for maximum contact stress estimation on acetabular surface in total hip replacement. The maximum contact stress has been described based on Wiberg's angle and patient's body.

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Fretting wear of total hip replacement femoral systems

Cook J. E., Lee A. J. C., Hooper R. M., Howell J.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

121-126

EN

This paper reports results from an on-going programme investigating the wear processes in cemented femoral stems and includes clinical studies and appropriate parallel laboratory tests. A number of femoral stem components removed during revision surgery have been examined and a consistent pattern of wear has been observed. Micromovement between a bone cement specimen and the metal substrate has been studied using a micro-sliding apparatus. Apparatus has been developed where axial and torsional forces can be applied to a femoral stem mounted in bone cement. The morphology and location of clinical wear damage has been successfully replicated on the femoral stems. The observed wear has been interpreted in terms of a fretting-like process between the prosthesis and the cement mantle.