Knee Joint Endoprosthesis Research Articles

Study of neuromuscular activity in preparation for revision knee arthroplasty

The results of an electromyographic study of 13 patients, aged 50–87 years, with aseptic instability of the components of a knee joint endoprosthesis at the stage of preparation for revision arthroplasty, who were treated at the Republican Scientific and Practical Center of Trauma tology and Orthopedics in the period from 2013 to 2020, were analyzed. To assess the orthopedic status, we used: clinical examination, radiography of the knee joint in 2 standard and axial projections, topogram and CT scan. lectrophysiological studies provide important information for elucidating the etiopathogenesis of knee joint endoprosthesis instability. One of the causes of instability may be an imbalance in the activity of the flexor and extensor muscles that develops during walking, subsequently leading to periprosthetic osteolysis, which occurs as a response to the formation of wear and tear products of the components of the endoprosthesis.

EFFECTIVENESS OF CORRECTION OF GERIATRIC STATUS OF ELDERLY PATIENTS WITH MOVEMENT CONSEQUENCES OF TOTAL KNEE ARTHROPLASTY USING PHYSICAL THERAPY

The aim of the study was to evaluate the effectiveness of the influence of the developed program of physical therapy on the parameters of the geriatric status of elderly patients with motor consequences of total knee arthroplasty in the long-term period after surgery. 
 Material and methods. 80 elderly people were examined. The control group consisted of 24 people without joint endoprostheses with no signs of geriatric syndromes. The comparison group consisted of persons with a knee joint endoprosthesis and sarcopenia with low rehabilitation compliance with respect to rehabilitation intervention. Representatives of the main group with a knee joint replacement and sarcopenia were engaged in a physical therapy program using functional training on the Prosedos platform, therapeutic exercises, massage, kinesiology taping, nutrition correction, and patient education. The effectiveness of the program was evaluated by the dynamics of the Senior Fitness Test, Tinetti-test (Performance-Oriented Mobility Assessment), Geriatric Depression Scale, Tampa Kinesiophobia Scale. 
 Results. The geriatric status of the examined patients was characterized by muscle weakness (statistically significant lag in parameters of physical status - coordination, static and dynamic balance, strength, flexibility, endurance, dexterity compared to their peers according to the Senior Fitness Test, Tinetti-test), high risk of falling, kinesiophobia and psycho-emotional depression, which increases the risk of loss of autonomy and death. The developed program of physical therapy revealed an improvement in the condition of the patients of the main group due to the influence on the links of the pathogenesis of geriatric syndromes due to the improvement of balance and gait parameters, reduction of the risk of falling and fear of movements, improvement of the psycho-emotional status in comparison with the initial indicators in all studied parameters (р<0.05). The low rehabilitation compliance of patients in the comparison group, despite the awareness of the risks of poly morbidity, was associated with the lack of improvement in the condition after a similar observation period. 
 Conclusions. Elderly patients with the consequences of total knee arthroplasty and signs of geriatric syndromes need to develop physical therapy programs that take into account and correct the specifics of each condition, which will increase the overall effectiveness of rehabilitation measures.

USE OF AN INDIVIDUAL TOOL FOR KINEMATIC ALIGNMENT OF THE LIMB AXIS DURING KNEE ARTHROPLASTY (CLINICAL CASE)

Objective. To give a clinical example where, under the conditions of gonarthrosis, the patient underwent preoperative planning using modern technologies of three-dimensional modulation; outline the stages of individual instrument preparation and for kinematic alignment of the axis of the lower extremity and installation of knee joint endoprosthesis components. Methods. A 69-year-old patient was diagnosed with stage IV right-sided gonarthrosis. For preoperative planning, a computer tomography of the lower extremities was performed in the position of full extension in the knee joints and neutral rotation of the feet (slice thickness 1 mm). A 3D model of the lower extremities was built in the "STL" format in the RadiAnt DICOM Viewer Version2021.2 program and imported into the FreeformPlus program. Preoperative planning was performed according to the principle of kinematic alignment to restore the constitutional axis of the limb and the inclination of the knee joint plane. The main stages of preparation of an individual instrument and carrying out operative intervention are given. Functional evaluation was performed before and after the operation at different stages according to the EuroQol-5D, KSS, HSS scales and a six-step functional test. Results. Individual navigation made it possible to precisely carry out resections of the articular ends and perform the planned kinematic alignment of the limb. According to the EuroQol-5D scale, the improvement of the patient's quality of life was determined, starting from the 3rd day after the operation. According to the KSS scale, an excellent result (85 points) was obtained 6 weeks after the surgical intervention, which remained after 3 months. The evaluation of the result of endoprosthesis according to the HSS scale after 6 weeks was 36 points, after 3 months — 38 points. Conclusions. A clinical example of the use of an original individual instrument for knee endoprosthesis showed the main advantages of the method — accurate installation of endoprosthesis components according to the preoperative design, which ensured high patient satisfaction and a good functional result.

A short review on SLM-processed Ti6Al4V composites

The advancements in computer-aided design, manufacturing, and additive manufacturing techniques attracted the researcher to apply various new methods with the unique combination of alloys and composites to design and develop complex parts. Among them the selective laser melting (SLM) process, a branch of additive manufacturing, and Ti6Al4V (Ti64) composite. Due to the better mechanical and corrosion resistance characteristics of Ti64 and its composites, they have been utilized for making various engineering parts related to jet engine fans of aero-engine, engine valves of automobiles, knee and hip joint endoprosthesis in the biomedical field, and corrosion resistance pipes in chemical industries. Also, more complex, net-shaped, and lattice-structured components can be fabricated by advancing the SLM process. The final quality of the parts manufactured from the SLM technique will depend on the fabrication process parameters followed. Many researchers have done research work on metal additive manufacturing by changing and optimizing the SLM process parameters such as laser power ( P), scanning speed ( v), hatch spacing ( d), and layer thickness ( h). Also, they have studied the effect of changes on the feedstock preparation, SLM process parameters, milling time of composite and post-heat treatment on the quality of Ti6Al4V composites. Therefore, a detailed review is needed to study the effect of the abovementioned parameters on the quality of metal additively manufactured parts through SLM. Hence, a short review is done on future challenges and opportunities of SLM-processed Ti6Al4V composites and reported in this article.

Some clinical factors of aseptic instability of the knee joint endoprosthesis

Background. Conducting clinical studies to determine the factors determining the aseptic instability of knee joint endoprosthesis components is an urgent issue in modern orthopedics. The aim of the study was to determine some clinical factors of aseptic instability of knee joint endoprosthesis components. Materials and methods. Comprehensive research was conducted on 285 patients who underwent primary knee arthroplasty between 2010 and 2021, including 85 patients with clinical and radiological signs of aseptic instability of knee arthroplasty components (AIKAC). Also, 200 patients made up a control group with no signs of AIKAC instability observed. Clinical research methods included general, and special orthopedic methods of studying local changes in the knee joint. They included measurement of body mass index (BMI), overloading of the knee joint due to work, previous surgical interventions and early postoperative complications of primary arthroplasty, and presence of angular deformities in the knee joint. For the clinical assessment of the knee joint of patients after knee arthroplasty, we used our own point assessment of the state of the knee joint. Results. It was determined that significant factors for the development of instability of components of the knee joint endoprosthesis are both directly related to the patient (increase in BMI, difficult working conditions, the presence of operative interventions on the knee joint), and factors related to errors during the primary total arthroplasty (residual deformities of the knee joint and early postoperative complications). Conclusions. We determined important factors of aseptic instability of the knee joint in the patients after arthroplasty. Taking into account the results of this study will improve the diagnosis and treatment of aseptic instability of the knee joint.

Stamping of a complex profile part made of hard‑to‑form alloys

Using the example of the process of obtaining semi‑finished components of knee joint endoprostheses, the stages of obtaining a complex profile forging are demonstrated. A comparative analysis of obtaining the same product from different alloys is given. The methodology is given and the results of determining the energy‑power parameters of hot volumetric stamping of hard‑to‑form VT1–0 and Co‑Cr‑Mo alloys are presented. A typical scheme of the technological process of manufacturing forgings with an elongated axis and significant thickness differences characteristic of endoprostheses is determined.

Анализ эффективности локального протокола диагностики перипротезной инфекции

The diagnosis of periprosthetic joint infection is a difficult task because there is no absolute test to confirm or rule out infection. We have developed a local protocol for diagnosing periprosthetic joint infection to use a combination of diagnostic studies with the highest level of sensitivity and specificity.The purpose of the study: To evaluate the effectiveness of a local protocol for diagnosing periprosthetic joint infection to determine surgical treatment tactics.Methods. We analyzed 283 audits that took place during 2020-2022 at the Federal Center for Traumatology, Orthopedics and Endoprosthetics (Smolensk, Russian Federation). Patients with a preliminary diagnosis of aseptic loosening of knee or hip joint endoprosthesis components and periprosthetic joint infection were monitored. All patients were examined in accordance with the local protocol for the diagnosis of periprosthetic joint infection, which includes clinical and radiological data, CRP and ESR, analysis of the cellular composition of synovial fluid, microbiological examination of biopsies, endoprosthesis components, planned and frozen sections. The final diagnosis was made taking into account clinical and laboratory data. The effectiveness was assessed by delayed treatment results. Results. Positive microbiological cultures were isolated in 165 patients (58%), 150 patients had increased cytosis of synovial fluid (53%), leukocyte esterase was increased in 147 cases, according to the results of an urgent histological examination, 159 conclusions of «infectious type membrane» (56%) were obtained, a combination of increased ESR and CRP was observed in 93 cases.Conclusions. Analysis of the local periprosthetic joint infection diagnostic protocol showed that each stage of diagnosis allows to identify additional cases of infection, therefore, all patients admitted for revision endoprosthetics should be examined throughout hospitalization. The inclusion of urgent histological diagnostics at the intraoperative stage makes it possible to change the tactics of surgical treatment in a timely manner. In general, the local protocol of step-by-step diagnosis of periprosthetic joint infection with the inclusion of urgent histological examination helps to increase the chances of a successful outcome of revision endoprosthesis surgery, regardless of the nature of loosening.

Long-term oncological results of patients with primary and metastatic tumors of the musculoskeletal system who underwent arthroplasty

Introduction. Primary malignant tumors of the skeletal system mostly develop in young and middle-aged people. Morbidity in this age group amounts to between 75 and 80 % of overall morbidity. Due to low survival caused by patient death in the first 5 years mostly because of metastases of primary malignant tumors, the main focus of treatment was on prolongation of life, study and development of new methods of conservative therapy. Therefore, until the early 1970 amputation surgery was the generally accepted standard of surgical intervention. Positive oncological results required revision of the surgical concept of treatment in this patient group. This problem was solved through active development of oncological endoprosthesis started in the second half of the 1970s and led to shaping of orthopedic oncology into a separate oncological specialty. The study objective is to study long-term oncological results of treatment of patients with primary and metastatic tumors of the locomotor system after oncological endoprosthesis.Materials and methods. The study included 1292 patients with primary sarcomas of the bones, soft tissues and patients with metastatic and benign bone tumors who underwent 1200 bone resections/extirpations of varying scale with endoprosthetic replacement between January of 1992 and January of 2020. In the total group of patients who underwent endoprosthesis, the number of men and women was approximately the same: 677 (52.4 %) and 615 (47.6 %), respectively. At the time of surgery, age of the patients in the total group varied between 10 and 81 years. Mean patient age was 34.7 years. Most commonly, endoprosthetic replacement was performed in patients between the ages of 21 and 30 years (in 29 % of cases). Oncological endoprosthesic replacement was performed in 814 (67.8 %) patients with primary malignant tumors, 143 (11.9 %) patients with metastatic lesions in long bones, and 243 (20.3 %) patients with benign neoplasms. Mean follow-up period after endoprosthesis of different bone segments was 82.8 months (between 0 and 335.7 months).Results. In 27 years of observations, total frequency of recurrences after endoprosthesis for various tumor locations (type V complication per the International Society of Limb Salvage system (2013) (ISOLS 2013)) was 8.8 % (86/979); among them recurrence in the bone (type VA complication) was observed in 1.7 % (17/979) of cases, recurrence in the soft tissues (type VB complication) in 7.0 % (69/979) of cases. Primary endoprosthetic replacement due to recurrence after previous surgical treatment leads to 2.2-time increase in the risk of development of this complication. The obtained results show that repeat recurrence significantly increases the risk of recurrence in soft tissues and does not affect the risk of recurrence in the bone. The most recurrences developed in patients with non-differentiated pleomorphic sarcoma (15.4 % of cases), chondrosarcoma (15.0 % of cases) and parosteal osteosarcoma (14.3 % of cases). Frequency of recurrences in patients with giant cell bone tumors and aneurysmal bone cysts was 4.0 and 3.8 %, respectively. In cases of tumor recurrence after endoprosthesis, limb amputation was the most common treatment: 33.7 % (28/83) of cases. In this study, recurrence mostly developed after femur resection with knee joint endoprosthesis: in 45.8 % (38/83) of cases. Frequency of oncological complications in patients with bone sarcomas who underwent endoprosthetic replacement was 31.9 % (283/886). In the total patient group in 27 years of observations, in 25.3 % (224/886) of patients disease progression in the form of metastases was observed. Local tumor recurrence was accompanied by metastases in 6.7 % (59/886) of cases.Conclusion. Decreased risk of development of local recurrences depends on the effectiveness of complex approach to therapy in this disease group. Changes in surgical endoprosthesis techniques in tumors of varying differentiation levels allowed to achieve significant radicalness of treatment. Progression risk for bone sarcomas, level of response to specialized therapy and, as a result, patient’s prognosis depend on the presence of epigenetic, genetic, molecular and chromosomal abnormalities.

Carbon emissions, techno-economic and machinability assessments to achieve sustainability in drilling Ti6Al4V ELI for medical industry applications

In the last decade, cryogenic machining has made a significant impact as a sustainable machining technique, demonstrating machinability improvements in terms of tool life, surface quality of machine parts, low environmental effects and reduced cost of overall machining operation. A near-to-dry machining technique, Electrostatic Minimum Quantity Lubrication (EMQL) has also emerged as a sustainable machining technique, which is an environmentally-friendly alternative to the flood machining process. Although these coolant/lubrication strategies have been studied extensively, there is no direct comparison of both these machining techniques in the aspects of ecology, economy and machining performances. In this novel study, cryogenic liquid carbon dioxide (LCO2) and EMQL techniques are used for high-speed drilling of Ti6Al4V ELI (extra low interstitial) grade, and the sustainability and machinability assessment of these techniques are evaluated which can help medical implant manufacturing industries to implement these techniques as an economic and sustainable replacement of the conventional cooling/lubrication techniques. Ti6Al4V ELI is widely used in the medical industry for Hip and Knee joint endoprosthesis, bone screws, collar bone and dental implants. The sustainability aspects were evaluated in terms of carbon emission and cost analysis of the processes. It was found that the EMQL cutting condition exhibited 27.69% higher carbon emission and 67.60% higher cost of machining operation compared to cryogenic LCO2 cutting condition. Moreover, the tool life experienced when machining using cryogenic LCO2 cutting condition was at least 4 times higher than tool life found when using the EMQL cutting condition. The surface roughness of the workpiece material was higher (56.40%) when using the EMQL coolant. These results were attributed to adhesion wear and chip clogging phenomena which were found to be the main factors for reduced tool life and higher surface roughness in EMQL cutting condition. Therefore, from this study, it can be concluded that cryogenic LCO2 coolant performs significantly better compared to EMQL coolant, providing improved machinability of the titanium workpiece and superior sustainability of the cutting operation.

Bilateral versus unilateral total knee replacement - comparison of clinical and functional results in two-year follow-up.

Total knee replacement is one of the most common surgical methods in diagnosis of end staged osteoarthritis. In this retrospective analysis, we focus on comparison of functional and clinical outcome in patients undergoing unilateral and bilateral replacement within a single surgical procedure. 54 patients (bilateral 19, unilateral 35) underwent total knee replacement in our clinic participated in the current study. The length of hospital stay was monitored in all patients. Assessment of functional results was based on the WOMAC score, KSS 1, KSS2, range of motion and presence of complications in both groups. Both groups of patients were homogeneous with age, body mass index and sex. The length of hospital stay in the unilateral group was 4.7±1.3 and 5.6±2.0 in the bilateral group. Patients operated on unilaterally achieved flexion of 114.9±9.3 after one year, bilateral group 112.6±8.6, the difference was insignificant. In both groups, there is a significant improvement one year postoperatively at WOMAC, KSS1 and KSS2. Comparing WOMAC, KSS1 and KSS2 between the unilateral and bilateral groups 3, 6, 12 months postoperatively, the differences are insignificant. The revision of implants in two-year follow-up reached 1.5% in unilateral group and 1.4% in bilateral group. Unilateral and bilateral knee joint endoprosthesis implantation is a successful surgical method in orthopedic practice. With conscious selection of patients, bilateral implantation may be more advantageous alternative, as the patient undergoes one operation and the associated risks.

Automation in arthrosis research.

Widespread medical studies require the analysis of suitable sample numbers to discover certain effects. Arthrosis treatment with hip and knee joint endoprostheses introduces multiple materials into the human body. Metal-containing implants may release several degradation products. Certain concentrations of chromium, cobalt, nickel, titanium and aluminum may affect multiple organs. The determination of metal concentrations in body fluids is one way to prevent severe intoxication from implants. In addition, the study of metal distribution and accumulation in individual organs will deliver extended information. In contrast to well automated high-throughput screenings, analytical measurements are mostly performed manually due to their complex process structure. A new study published in the journal Molecules presents a semi-automated sample preparation and measurement system for the determination of metals in autopsy tissue using inductively coupled plasma mass spectrometry (ICP-MS). In this auto-commentary, the main findings are highlighted and discussed.

One-stage bilateral total knee arthroplasty

Total knee arthroplasty (TA) is one of the most successful orthopedic surgeries performed in the last decades providing a high degree of patient satisfaction. But there is still controversy regarding the safety and efficacy between simultaneous bilateral TA (SBTA) or two-stage bilateral TA (TSBTA). The purpose of the study is to initiate a database of patients after SBTA for radiological monitoring of the condition of patients and knee joint endoprostheses. For the period 2014-2021 SBTA was performed in 230 patients with bilateral gonarthrosis 3rd stage: women – 167 (72.6%), men – 63 (27.4%). The age of patients – from 30 to 84 years. The body mass index (BMI) ranged from 22.5 (patient, 76 years old) to 48.7 (patient, 52 years old). Investigation design. Inclusion criteria: bilateral gonarthrosis in the 3rd stage of the disease with severe pain and severe functional impairments. Exclusion criteria: polymorbid diseases in the acute stage, morbid obesity, past myocardial infarction, stroke, varicose veins of the lower extremities, obesity, chronic heart failure, chronic renal failure, anemia of various origins (hemoglobin less than 110-115 g/l), HIV, uncompensated sugar diabetes, hidden foci of untreated infection. Conclusion. Patients should be selected for SBTA/TSBTA and consulted on the based of the risks associated with each strategy. The ability to provide effective assistance in complex cases provides patients with high satisfaction and increases the prestige of the clinic. A database of patients after SBTA was created for radiological monitoring of the condition of patients and knee joint endoprostheses.

Assessing risks of developing and persistence of infectious process in knee joint replacement

Despite of intensive work on improving endoprosthetic replacement constructions, using minimally invasive techniques, developing methods of prevention for and treatment of periprosthetic joint infection, relapse of infection process can reach up to 52 % after treatment.The aim of the study: to show the importance of identifying the risks of development and recurrence of periprosthetic infection after implantation of a knee joint endoprosthesis. A clinical case of the development of a deep periprosthetic infection in a patient after primary knee replacement and successful treatment of the resulting complication was demonstrated. The analysis of this case of an infectious complication using the proposed prognosis for the development of periprosthetic infection showed that before surgical treatment of the patient, the risk of an infectious process was not assessed, and appropriate preventive and therapeutic measures were not carried out.Materials and methods. In the treatment of developed periprosthetic infection of the knee joint, the author’s algorithm for choosing surgical tactics was used, which allowed to determine the high risk of recurrence of periprosthetic infection, evaluate additional criteria and choose the optimal type of surgical intervention – two-stage revision endoprosthetic, which allowed to stop the infectious process.New was the use of the proposed prognosis for the development of periprosthetic infection and the algorithm for choosing surgical tactics for periprosthetic infection, which make it possible to determine the necessary preventive measures to reduce the risk of an infectious complication and to apply the optimal type of surgical intervention to relieve periprosthetic knee infection.

Experimental substantiation of the optimal technique for choosing the rotation of the femoral component of the knee endoprosthesis

There was experimental justification of the optimal technique for choosing the rotation of the femoral component of the knee joint endoprosthesis carried out in this research. The individual morphometric characteristics of the femoral condyles and the condition of the collateral ligaments were taken into account in the experiment. The research was conducted on polymer-embalmed preparations of the knee joint, which were divided into three groups, according to the forms of the femoral condyles. We used the standard technique of positioning the resection block and the technique of individual selection of the rotation of the resection block (rotation of the femoral component of the endoprosthesis), based on the assessment of individual morphometric characteristics of the femoral condyles and the state of the auxiliary elements of the knee joint. To implement this surgical approach, typical resections of the proximal condyles of the tibia and distal condyles of the femur were performed, which technically did not differ from the sawdust used in the standard procedure. Then the knee joint was flexed to an angle of 90, Homan retractors were removed and two laminar dilators (Laminar Spreader) were installed in the gap between the proximal tibial sawdust and the posterior parts of the lateral and medial condyles of the femur. This technique provided isometric tension of the fibular and tibial collateral ligaments of the knee joint. Then carried out the positioning of the femoral resection block "four in one". In this case, only the line of the proximal tibial sawdust was used as a reference point, for which the posterior flange of the resection block was positioned parallel to the sawed upper articular surface of the tibia. It is established that the use of the considered technique of positioning the femoral resection block ensures the formation of a uniform flexor gap, regardless of the variant anatomy of the femoral condyles. Thus, there was research a uniform flexion gap in the experiment, which ensured isometric movements in the knee joint and its stability at the control points of the amplitude after implantation of the trial or final components of the endoprosthesis.

KONSTANTIN SIVASH - CONSTRUCTOR OF UNIQUE ENDOPROTHESIS

The author briefly describes the history of the creation of the hip joint endoprotheses, as well as the biography of Professor Konstantin Sivash, the implementator of a unique one-piece hip joint endoprosthesis, original knee and elbow joint endoprostheses, compression apparatus for the knee joint, plates and pins for osteosynthesis of fractures.

Effect of Physiological Saline Solution Contamination on Selected Mechanical Properties of Seasoned Acrylic Bone Cements of Medium and High Viscosity.

Bone cements play a key role in present-day surgery, including the implantation of hip and knee joint endoprostheses. The correct and durable bonding of the prosthesis to the bone is affected by both the static strength characteristics determined in accordance with ISO 5833:2002 and the resistance to long-term exposure to an aggressive environment of the human body and the impurities that may be introduced into the cement during implementation. The study attempts to demonstrate statistically significant degradation of cement as a result of the seasoning of cement samples in Ringer’s solution with simultaneous contamination of the material with saline solution, which is usually present in the surgical field (e.g., during the fixing of endoprostheses). The results of statistical analysis showed the nature of changes in compressive strength and microhardness due to seasoning time and degree of contamination.

PERSEPT3: A Phase 3 Clinical Trial to Evaluate the Hemostatic Efficacy of Eptacog Beta (Recombinant Human FVIIa) in Perioperative Care in Subjects with Hemophilia Α or B with Inhibitors

PERSEPT3: A Phase 3 Clinical Trial to Evaluate the Hemostatic Efficacy of Eptacog Beta (Recombinant Human FVIIa) in Perioperative Care in Subjects with Hemophilia Α or B with Inhibitors

COMPARATIVE ANALYSIS OF COMPLICATIONS IN PATIENTS AFTER INDIVIDUAL ONCOLOGICAL AND MODULAR ONCOLOGICAL ENDOPROSTHETICS OF THE KNEE JOINT WITH TUMOR LESIONS

The article contains analysis of complications after individual oncological knee joint endoprosthesis replacement in cases of tumor lesions. Complications were observed in 45 ,8% of cases after knee joint endoprosthesis replacement operations with tumor lesions. The main complications that were observed included infectious ones: 18,1%, aseptic instability of the endoprosthesis stem: 16,7%, bone fracture at the site of endoprosthesis stem implantation: 6,9%, destruction of the endoprosthesis structure: 4,2%. The factors that led to complications, as well as methods of their elimination are given. Dialysis and a long course of antibiotic therapy or the installation of a metal-cement spacer device followed by repeated endoprosthesis replacement is advised in case of an infectious complication. Repeated joint endoprosthesis replacement with replacement of only one (loose) component of the endoprosthesis, using a long intramedullary stem or replacement of the total endoprosthesis is advised in case of aseptic instability of the endoprosthesis stem. Metallic osteosynthesis of the periprosthetic bone fracture is performed using bone plates and cable grip in cases of bone fracture at the site of endoprosthesis stem implantation. Repeated joint endoprosthesis replacement is effected with replacement of the entire endoprosthesis structure in case of destruction of the endoprosthesis structure.

Effect of manufacturing technique on material homogeneity of an implant made of polyetheretherketone

Polymer insert is one of the components of a knee joint endoprosthesis, allowing patients to sustain their mobility. They are mostly made of ultra-high molecular weight polyethylene (UHMWPE) that is not without flaws. Inserts can be manufactured by machining (substractive techniques) or by the use of rapid prototyping techniques (additive manufacturing). In order to increase their strength, is increasingly being considered replacing UHMWPE with polyether ether ketone (PEEK). This material has been analyzed in this work due to the growing interest in using this material for the production of implants. This study contains a comparative analysis of two inserts made using two different methods. Its aim is to verify the effect of the manufacturing technique on material uniformity.

Wear Morphology on the Surfaces of CoCrMo Unicompartmental Knee Joint Endoprostheses as Elements of Metal-Metal Friction Nodes.

The article assesses the strength and structural parameters of load-bearing layers of metal biobearings made of CoCrMo alloy. The research material consisted of unicompartmental knee joint endoprostheses used in the human body, removed due to excessive wear. No patient participated in the examinations. The endoprostheses used as research material underwent the liquidation procedures in the hospital, which has all necessary permissions and certifications to perform endoprosthetic procedures. Endoprostheses selected for the examinations had been used for 6 to 12 years at similar load conditions as declared by the patients, i.e., body weight of F = 835 N, declared activity expressed as the number of load cycles up to 100 thousand/year, and no artificial joint infections. To assess the homogeneity of the research material, the analysis of chemical composition using a Joel scanning electron microscope with EDS (Energy-dispersive X-ray spectroscopy) was made to exclude endoprostheses with various alloying additives. Microscopic examinations were performed using the Phenom XL microscope, while the wear surface was examined using a Keyence VHX-900F microscope. Several experimental tests were also carried out on load-bearing surfaces to assess changes in strength parameters of the base material after a known life cycle and load conditions. Material hardness using the Vickers method, yield point, critical value of stress intensity coefficient, and the coefficient of friction µ were evaluated. The examinations allowed for the systematization of wear in the knee and femoral components of unicompartmental hip endoprostheses. The statistical evaluation of the number and costs of hip joint replacement surgeries in Poland was also made.