Endoprosthesis Head Research Articles

STAND FOR TRIBOLOGICAL STUDIES OF HIP JOINT ENDOPROSTHESIS WITH THE POSSIBILITY OF CHANGING ACETABULUM ANTEVERSION ANGLE AND HEAD ANTI TORSION ANGLE

The article presents the construction of a hip joint movement simulator intended for friction and wear studies of hip joint endoprostheses. The simulator's design enables the fixing of hip endoprosthesis components in accordance with the anatomical structure of the human hip joint. The endoprosthesis head is mounted on a special base in the lower position with a neck-shaft angle of 135°, while the acetabular cup of the endoprosthesis is mounted in the upper part of the mounting head with an inclination angle of 45°. The production of three heads (responsible for the anteversion angle of the acetabulum) and three special bases (responsible for the anti torsion angle of the head) with different fixing angles of the components of the hip joint endoprosthesis made it possible to carry out tribological tests with nine variants of alignment settings. The hip joint endoprosthesis tester is designed to simulate the following movements: flexion and extension, as well as loads occurring in the human hip joint while walking. Thanks to the use of control in the form of electronic cams, the simulator makes it possible to recreate the variable value of the force loading the friction pair as a function of the human walking cycle. The subject of friction and wear studies were hip joint endoprostheses with a head diameter of 44 mm, made of high-carbon Co28Cr6Mo alloy. For each of the nine variants of endoprosthesis component alignment settings, average friction coefficient values were calculated based on the recorded values of the friction torque. The results of the friction and wear studies employing the simulator confirm that the mutual angle alignment setting of the head and the cup has an impact on the value of the frictional resistance occurring in the tribological pair.

The Risk Factors of the Hip Dislocation After Total Hip Arthroplasty (Literature Review)

Summary. The dislocation of the endoprosthesis head is one of hip arthroplasty complications. In the vast majority of cases, the cause of dislocation is multifactorial. That is why only a thorough analysis of the patient’s peculiarities, surgery and rehabilitation will help to avoid the relapse. Risk factors associated with the patient include: old age, male gender, obesity, concomitant diseases, low level of preoperative physical activity, low compliance, and some others. The problem of biomechanical ratio in the segment “spine – pelvis – lower limb” deserves special attention. Besides, there are risk factors associated with the surgeon: access option, type of implant, fixation and position of endoprosthesis components, experience and surgical technique of the orthopedic surgeon. The strategy of dislocations rate reduction is based on a detailed study of dislocation causes and their elimination, and adequate surgery planning. The treatment of a patient with dislocation should take into account the multifactorial etiology of the condition.

Reccurence of Heterotopic Ossification as the Result of Total Hip Endoprosthesis Dislocation: A Case Report

Background. Heterotopic ossification (HO) is the formation of mature bone in soft tissues. HO in the hip area can be a consequence of both injury to the nervous system and local trauma. After total hip arthroplasty HO develops in 30% of cases.
 The aim of the study is to demonstrate a rare clinical case of a recurrence of HO in patient after a primary total hip arthroplasty, accompanied by ankylosing.
 Case presentation. A 32-year-old patient was admitted to the clinic for revision hip arthroplasty with a diagnosis long-standing dislocation of the right hip joint endoprosthesis head, heterotopic ossification 3 years after dislocation. During the surgery, there were difficulties with the sciatic nerve dissection, as well as the structures of the endoprosthesis. We removed all the ossifications that obstructed the dislocation of the endoprosthesis. The patient had sciatic nerve neuropathy on the right lower limb with lesions of the fibular and tibial nerves on the background of edema. The patient was discharged on the 21st day. The presented clinical case is interesting because the patients relapse could be caused by a combination of various risk factors. Taking into account the fact that the injury was received as a result of an accident and the patient had a fracture of the bones of the contralateral shin, it could be the effect of a local hip injury that aggravated the process.
 Conclusions. This clinical observation highlights the importance of preventing possible complications after surgery and maintaining feedback with patients, especially those belonging to the high-risk group. It is likely that with adequate prevention of the HO formation and timely reduction of dislocation, the problems described in the article after primary total hip arthroplasty could have been avoided.

Outcomes and complications of organ-sparing treatment of patients with tumor and tumor-like conditions of the forearm long bones

Introduction.Surgical treatment of tumors of the distal part of the forearm has always been complicated. Though there are many methods of reconstruction of defects of the long bones of this area after resection, the optimal technique is still debated.The study objectiveis to analyze the results of surgical treatment of tumors and tumor-like conditions of the forearm long bones, rate of postoperative complications, and techniques of their correction.Materials and methods. The article presents data on 75 patients with tumor and tumor-like conditions of the forearm long bones. Diagnosis was histologically verified. In 58 (77.3 %) patients, benign giant cell tumor was diagnosed, in 3 (4 %) patients – malignant giant cell tumor, in 3 (4 %) patients – osteogenic sarcoma, in 3 (4 %) patients – chondrosarcoma, in 6 (8 %) patients – fibrous dysplasia. All patients underwent surgical treatment of varying volume. During the study, analysis of complications of surgical treatment was performed.Results.Postoperative complications of various nature developed in 17 (22.7 %) of 75 patients between 2 weeks and 2 years after treatment. They mostly developed after segmental resection of the forearm bones with autoplasty (38.1 %) and segmental bone resection (21.4 %), as well as after excochleation with cementoplasty (16.1 %). The most frequent complications were autotransplant lysis (in 4 (19.1 %) cases), its fracture (in 2 (9.5 %) cases), and infections and inflammatory complications (in 2 (9.5 %) cases). After segmental resection with endoprosthesis, only 1 (11.1 %) patient experienced endoprosthesis head instability in the early postoperative period which led to re-endoprosthesis. Local recurrence was observed in 6 (19.4 %) of 31 patients with gigantic-cell tumors after excochleation and in 4 (28.6 %) of 14 patients after segmental resection. In 2 (14.3 %) cases, progression of the main disease was observed in the form of pulmonary metastases.Conclusion.Excochleation with cementoplasty is the method of choice in benign tumors of the forearm bones in the absence of soft-tissue component, destruction of the cortical layer, advancement of the tumor to the joint surface. In case of benign tumors in the absence of soft-tissue component and destruction of the cortical layer, and in the presence of tumor advancement to the joint surface, the optimal technique is segmental bone resection with substitution of the defect with endoprosthesis.

Основні критерії прогнозування вивиху головки ендопротеза у хворих із переломами шийки стегнової кістки після однополюсного ендопротезування кульшового суглоба

Мета. Визначення основних кількісних критеріїв прогнозування вивиху головки ендопротеза кульшового суглоба у пацієнтів з переломами шийки стегнової кістки при однополюсному ендопротезуванні на основі ретроспективного та проспективного аналізів результатів лікування. Матеріали та методи. Проведено ретроспективний аналіз протоколів клініко-рентгенологічного обстеження 20 хворих (5 чоловіків, 15 жінок віком 55–86 років) із переломами шийки стегнової кістки після первинного ендопротезування кульшового суглоба за загальноприйнятою методикою у 2000–2015 рр.; проспективне дослідження результатів нового способу однополюсного ендопротезування кульшового суглоба зі збереженням капсули суглоба (патент України № 119611) в 11 пацієнтів (4 чоловіки, 7 жінок віком 66–92 роки) з переломами шийки стегнової кістки, які проходили лікування у 2013–2016 рр. Всі хворі спостерігалися у Державній установі «Інститут патології хребта та суглобів ім. проф. М.І. Ситенка НАМН України» (м. Харків). Результати. Основні фактори ризику вивиху головки ендопротеза після однополюсного ендопротезування кульшового суглоба з приводу переломів шийки стегнової кістки — похилий вік (90,0 %), слабкість м’язів, що оточують кульшовий суглоб (90,0 %), надмірні рухи у суглобі у післяопераційному періоді (80,0 %), попередні оперативні втручання на кульшовому суглобі (70,0 %), надмірна маса тіла (60,0 %). У даної категорії хворих установлено чисельні значення прогностичних коефіцієнтів та їх інформативності для вірогідних пацієнто-, імпланто- та хірургічно залежних факторів ризику вивиху головки ендопротеза. Висновки. Запропонований авторами спосіб профілактики та лікування вивиху головки ендопротеза через збереження капсули кульшового суглоба при первинному однополюсному ендопротезуванні хворих із переломами шийки стегнової кістки забезпечує сприятливий результат хірургічного лікування, незважаючи на наявність факторів ризику вивиху головки ендопротеза у післяопераційному періоді.

Двойная мобильность ацетабулярного компонента как способ артропластики тазобедренного сустава у пациентов со сложной ортопедической патологией

Due to the increase in the number of total hip arthroplasty operations throughout the world, the prevention of such complication as the endoprosthesis head dislocation is of paramount importance. The aim of this work is to familiarize specialists with the capabilities and the first experience of using the system with double mobility of the acetabular component as the most modern solution for the prevention of the endoprosthesis head dislocation during primary or revision arthroplasty of the hip joint. Based on the literature data, an analysis of the causes of the endoprosthesis head dislocation during hip arthroplasty is presented. The historical aspects and the first results of using the system with double mobility abroad are considered. The article presents the authors’ positive clinical experience of using this system in 22 patients with an increased risk of the endoprosthesis head dislocation.

Optimization of total hip arthroplasty for dysplastic coxarthrosis

Degenerative-dystrophic hip damages are among urgent problems, for which endoprosthesis replacement is considered a relevant solution for 100 to 300 cases per 100,000 population per year. Aseptic instability of the endoprosthesis components dominates the environment of unsatisfactory outcomes in the long term. To prevent aseptic instability of the hip endoprosthesis components in the hip pathology, the authors propose a method of "incision" on the tendon part m. iliopsoas and use of the intraoperative method to determine the centre of the endoprosthesis head rotation. This work analyses the surgical treatment method of 103 patients operated on in the traditional way and 91 patients who underwent surgical incision of the m.iliopsoas tendon using the intraoperative method to determine the centre of the endoprosthesis head rotation.

Dislocations after Hip Arthroplasty (Review)

One of hip arthroplasty complications is dislocation of the endoprosthesis head. In the vast majority of cases, the cause of dislocation is multifactorial. That is why only a thorough analysis of the patient’s peculiarities, surgery and rehabilitation will help to avoid the relapse. This review analyzed the risk factors of dislocation and treatment tactics. Risk factors associated with the patient include: old age, male gender, obesity, concomitant diseases, low level of preoperative physical activity, low compliance and a some others. The problem of the biomechanical ratio in the segment “spine – pelvis – lower limb” deserves special attention. Besides, there are risk factors associated with the surgeon: access option; type, fixation and position of endoprosthesis components, experience and surgical technique of a orthopedic surgeon. The strategy of dislocations rate reduction is based on a detailed study of dislocation causes and their elimination, and adequate surgery planning. The treatment of a patient with dislocation should take into account the multifactorial etiology of the condition.

Total hip replacement in femoral head osteonecrosis

The experience of hip replacement in young patients with osteonecrosis of the femoral head was analyzed in the article. The results of operations in the osteonecrosis group and osteoarthritis group in 3 years and 7 months after operations were compared. In 97.5 % of cases, cementless fixation implants with a ceramic on ceramic friction pair (45 %) and ceramic on polyethylene friction pair (45 %) were used. Surgical approaches by Moore, Hardinge and AMIS technique were applied. The clinical results of operations in the studied groups were similar, but the survival rate of endoprostheses in the osteonecrosis group was 91.5 %, and in the osteoarthritis group 97.2 %. In the osteonecrosis group an increased frequency of complications (dislocation of the endoprosthesis head, periprosthetic fracture, periprosthetic infection) and revision operations were observed. Our results show the influence of risk factors, concomitant diseases, the level of activity of young patients on the long-term total hip arthroplasty result.

Estimation of efficiency of hip joint capsule cut fixation with polypropylene mesh

Relevance. Dislocation of the femoral component of the endoprosthesis is one of the most frequent complications in the total hip joint endoprosthesis (THJE). There are many factors for the development of dislocations. The best option to «treatment» a dislocation in THJE is to prevent the development of primary instability. Of particular relevance to the restoration of the capsule-ligament apparatus is for people with obesity. Careful restoration of soft tissue structures or the preservation of these structures using modified accesses significantly reduces the incidence of dislocations. Currently developed many ways to strengthen and restore the posterior structures of the hip joint capsule. In this paper, we study a method for restoring and strengthening the posterior structures of the hip joint capsule using polypropylene-based mesh implants. Purpose: to evaluate the effectiveness of using a polypropylene mesh to close a defect in the hip joint capsule. Materials and methods. The study was carried out in a software package based on the finite element method. For the rational use of computer resources, a computational model was built, which consisted only of the capsule model and the endoprosthesis head model. The dimensions of the elements of the computational model corresponded to the actual dimensions of these objects. In this paper, two ways of capsule suturing were investigated: interrupted sutures and polypropylene mesh. Also, an additional control model of the same dimensions was constructed, but in which the incision was not sutured. Results and its discussion. As a result of the calculations, pictures of the distribution of the stress-strain state in the «head-capsule» system were obtained. To assess the effectiveness of the method of closing the capsule, as the main characteristics, the values of the opening of the incision, as well as the stresses arising in the joint capsule, were chosen. An additional characteristic is selected stresses in the head. Conclusions. The obtained calculation results indicate that with the considered options for fixing the cut, both in terms of rigidity and strength, the model of fixing the defect with a mesh is more effective.

Closure of the hip joint capsule defect with a propylene mesh. Clinical and biomechanical research

Dislocation of the femoral component of the endoprosthesis is one of the most common complications after hip total arthroplasty. The best way of prevention is to prevent the development of primary instability. Even with the proper positioning of endoprosthesis components, there are dislocations associated with the weakness or defect of the capsular-connective structures of the joint. Today, a lot of ways have been developed to strengthen and restore the posterior structures of the capsule of the hip joint with the help of auto and allomaterials, differing in the method of fixation and physical and chemical characteristics.The paper proposes a method of restoring and strengthening the posterior structures of the capsule using polypropylene mesh implants. Objective: to construct a model of the hipjoint capsule after capsulotomy with the help of the specialized software program and to determine the hardness of the defect closed with a polypropylene mesh. Methods: the study was made in a software complex based on the finite element method. A calculation model was constructed consisting of capsule and endoprosthesis femoral head. Two methods of sewing the dissected capsule were studied: seam thread and polypropylene mesh. In the control model, the capsule was not fixed. Results: pictures of the distribution of stress-strain state in the system «endoprosthesis – joint capsule» were obtained. Conclusions: underthe conditions of the kinematic loading of the model, the smallest sizes of the capsule cut opening are in case of its closure with the mesh. In the case of thread, they were 8.5 % higher. The values of equivalent stresses in the model with the mesh were the largest: in the capsule of the joint by 23.8 %, the endoprosthesis head — by 60.4 % compared with the thread fixation. The obtained results indicate that the mesh model is more rigid.

Graph analytical study of the possibility of prevention and treatment of dislocation of the hip joint head because of the incorrect position of its components

Objective: to determine the mechanisms of the disloca­tion of the head of the hip joint endoprosthesis on the basis of the graphoanalytic modeling method and to correct the wrong position of its components. Methods: graphical-analytical model­ing. Results: it has been established that there are two mecha­nisms of dislocation of the head of the hip joint endoprosthesis, related to its size and compliance with the angles of inclination and anteversion of the cup and antithesis of the endoprosthesis stem. The loss of contact area can also occur due to the wear of the friction pair. The most stable are endoprostheses with large-diameter heads, which allow increasing the shoul­der strength, which counteracts the disabling effect. As a mea­sure to prevent dislocations, you can use liners with a visor that prevent the dislocation of the head or neck of the endo­prosthesis of a reduced diameter. If the endoprosthesis cup has too much angle of inclination or insufficient cup anteversion and/or antithesis of the stem, but there is a stable anchorage, a liner with a visor can also be used. The angle of the movement of the endoprosthesis head due to the use of a liner with a vi­sor decreases with increasing diameter of the heads, which also indicates the advantage of using them to prevent dislocation of the endoprosthesis. Conclusions: in the hip joint endopros­thetics for the prevention of head dislocation, it is important to observe the correct position of its components. If it is not pos­sible to install the components of the endoprosthesis within the limits that prevent the appearance of dislocation of the head, and also for the purpose of its elimination, it is advisable to use liners with a visor in combination with large diameter heads. The choice of the neck of the endoprosthesis with a reduced di­ameter reduces the risk of its dislocations.

Mathematical modeling of dynamic loading features of hip joint after resection of proximal femur tumors

The problem of achieving positive results in the treatment of patients with tumors of the upper third of the femur remains relevant. Among the methods for studying the functioning of the hip joint and for analyzing the specific loads it is used mathematical modeling method. Purpose: using the method of mathematical modeling, to study the characteristics of dynamic load in hip joint with the presence of bone and soft tissue post-resection defects in the upper third of the femur.Methods: in this study method of mathematical modeling by OpenSim software has been used. Basic muscle-skeletal model and created models with reproduction of hip joint condition after the resection of malignant tumor of the upper third of the femur and proximal femur replacement with and without myoplasty used. Load transmitted from the endoprosthesis head to the acetabulum studied. Results: it is revealed change of load direction from the anterior toward posterior acetabular wall with threefold volume in comparison to basic model was defined during the modeling process and analyzing of significant defects in femoral abduction and flexion muscles with substitution of proximal femur defects using modular endorposthesis. Also, important decline of pressing load to the acetabular bottom noted. This situation results in severe function impairment of the lower extremity and determines hip joint instability. Method of abduction muscles repair at the cost of proximal transposition of m. vests laterals allows to compensate load changes in the acetabulum.Conclusion: reproduction of abduction muscle defects in the model results in load direction changes in anteposterior direction, functional impairment of the lower extremity and increases risk of hip joint instability. Appropriate method of abduction muscle defects repair using m. vastus laterals is presented.

FEATURES OF REHABILITATION OF THE PATIENTS AFTER NONINFECTIOUS COMPLICATIONS OF TOTAL HIP ARTHROPLASTY

The authors analyzed noninfectious complications (dislocation of endoprosthesis head, periprosthesis fractures) in 8 patients out of 40 with hip arthroplasty. There were estimated clinical, biomechanical results and quality of life of the patients. An application of the external fixator-orthezes should be recommended in order to prevent complications of hip replacement. The wearing of brace is considered to be reasonable after revision interventions.

Grindability of Single Crystal Sapphire in Medical Use and the Scheme of Forming Highly Precise Spherical Heads

The scale of influence of the single crystal sapphire crystallographic plane orientation and grinding conditions on the material removal rate, surface finish and the state of sub-surface layer have been studied under Low-Temperature Precision Grinding (LPG). The schemes of forming partial spherical heads for human hip joints endoprostheses are considered and elaborated. The possible versions of forming the spherical heads of endoprosthesis based on the novelties in kinematics and the mode of material removal are discussed.

Risk factors for dislocation of a cementless total hip endoprosthesis--a statistical analysis

This retrospective study aimed at the statistical identification of risk factors for dislocation for a certain cementless hip endoprothesis. At our department 2605 primary total hip arthroplasties were performed between 1987 and 1997. In 40 patients (1.5%) a dislocation occurred. These patients were compared with a control group matched in number. No difference was found in both groups with respect to age, height, weight, body-mass index, and diagnosis. A tendency was found that more males were involved in the dislocation group. There were more previous operations found in this group (p = 0.005). Also significant was the fact, that patients in the dislocation group more often had epidural anaesthesia (p = 0.02), more often the implantation of the smaller 28-mm head (vs. 32 mm) (p = 0.02), and a higher inclination angle of the acetabular component (p = 0.02). No difference was found in terms of the surgeons experience, the postoperative leg length, femoral offset, medialisation, cranialisation and antetorsion of the acetabular component. Dislocation after total hip arthroplasty is a multifactorial complication. With the use of the Alloclassic/Zweymüller total hip endoprothesis, a higher risk for dislocation was found for patients with previous hip surgery, the use of the smaller endoprosthesis head, a high acetabular inclination angle, and in the use of epidural anaesthesia.