Hip Endoprosthesis Research Articles

Rehabilitation of Patients with Hip Joint Arthroplasty (Late Post-surgery Period - Hospital Rehabilitation).

Hip joint replacement (endoprosthesis, alloplasty) has become one of the most frequent surgery interventions of the 20th century. To conduct rehabilitation therapy in the late post-surgery period of hospital rehabilitation (45 days after surgery), to track patients' progress and measure the results. One hundred and fifty-two patients with hip joint endoprosthesis were included in the study. All underwent surgery and rehabilitation at the Department of Clinical Rehabilitation of the Physical and Rehabilitation Medicine Clinic at Doctor G. Stranski University Hospital, Pleven. Kinesitherapy included therapeutic massage, isometric exercises for gluteal and hip muscles, isotonic exercises for the hip and the knee joint, breathing exercises, analytical gymnastics, exercises for balance and posture stability; gait control, exercises with gym equipment; occupational exercises included all activities of daily living (ADL) that were practiced at home; treatment with performed physical factors included applying magnetic field, interferential current therapy, electrostimulation of the m. quadriceps femoris and the gluteal muscles. The scores from the pain visual analog scale (VAS), the muscle strength test and the test for the movement volume of the hip joint were obtained at the beginning and at the end of the rehabilitation process and stored in an individual file for each patient. The results of the present study suggest that the complex rehabilitation program (kinesitherapy, performed physical factors and occupational therapy) can result in a considerably faster recovery and ensures that patients reach optimal functional results.

Two stage revision hip arthroplasty in periprosthetic joint infection. Comparison study: with or without the use of a spacer

PurposeThe aim of this study was to compare two methods of two-stage surgery for PJI (periprosthetic joint infection) after THA (total hip arthroplasty): one with and one without the use of an antibiotic-loaded cement spacer.MethodsThis retrospective study was performed on 99 consecutive patients (99 hips) with a minimum follow-up of 24 months. Patients were divided into two groups: (1) in whom the operation was performed using a spacer, and (2) for whom a spacer was not used.ResultsFor the whole cohort, the results improved between pre-operative and final follow-up. Recurrence of infection was found in nine out of 98 patients (9.2%) and was not significantly different between the two groups. Patients treated with a spacer had better functional improvement in the interim period, but the VAS score was better in the non-spacer group. The improvement in final function was better in the spacer group with regard to HHS, but not according to WOMAC score or VAS at final follow-up.ConclusionThe resection arthroplasty should be awarded particular consideration in cases of poor soft tissue quality, bone stock deficiency, when complications related to spacer use are expected or chances of new hip endoprosthesis implantation are low.

Influence of the fixation region of a press–fit hip endoprosthesis on the stress–strain state of the “bone–implant” system

Although significant progress has been made in the development of total hip replacement, behaviour of the femoral component of an endoprosthesis in relation to the type of its fixation in the bone is still not fully understood. In this paper, behaviour of the femoral bone and the stem prosthesis is studied taking into account different types of prosthesis fixation in the medullary canal of the femur under the action of functional loads. For an analysis, a three-dimensional model of a femur has been developed based on the results of a computed tomography. The stress–strain state governing behaviour of the femoral bone and the stem prosthesis has been estimated with the use of the finite element method (FEM).The FEM analysis has shown that for the diaphyseal fixation, the area of contact between the surface of the endoprosthesis and the bone is insufficient and leads to large stresses in the implant accompanied by stress concentration in the distal femur. An increase in the area of contact between the implant and the bone raises the stiffness of the "bone–implant" system, which, in turn, reduces stresses in the implant. The applied metaphyseal-type fixation yielded an improvement of results regarding behaviour of the femoral bone and the stem prosthesis. Namely, the study yielded the distribution of stress in the bone similar to the physiological stress state.

Influence of amorphous carbon layers on tribological properties of polyetheretherketone composite in contact with nitrided layer produced on Ti6Al4V titanium alloy

The key issue in bone implants biomechanics is – besides using biocompatible materials - the optimization of tribological properties of friction pairs occurring in joint implants e.g. knee and hip endoprothesis. Increasingly important role in these systems, alongside ceramics-on-ceramics and metal-on-metal, have metal-on-polymer friction pairs. Commonly used in orthopedics ultra-high molecular weight polyethylene (UHMWPE) does not meet the requirements of modern bone implants, mainly because of its harmful wear products which can cause inflammation and osteolysis of surrounding tissues after several years of using the endoprosthesis. Therefore, other polymer materials have been developed to replace UHMWPE, as well as several surface engineering methods are used for enhancing biocompatibility and tribological properties of applied materials. One of the materials to replace UHMWPE is increasingly used in medicine polyetheretherketone (PEEK) – a polymer material with a high biological indifference and mechanical properties.The article presents characteristics of TiN+Ti2N+αTi(N) nitrided layer produced on Ti6Al4V titanium alloy using glow discharge assisted nitriding process at the plasma potential, also known as the active screen plasma nitriding process and hydrogenated amorphous carbon doped with nitrogen layer a-C:N:H produced via RFCVD process on PEEK-based composite consisting of 10% graphite, 10% carbon fibers and 10% PTFE. Tribological properties of a-C:N:H – TiN+Ti2N+αTi(N) friction pair using “ball-on-disc” and “block-on-roll” tests were examined in correlation with microstructure (TEM, SEM, Raman spectroscopy) and surface morphology and topography (SEM, AFM, optical profilometer).The goal of this work is to present a new possibility of material solution for a ‘head-acetabulum’ friction pair in hip joint endoprosthesis using PEEK (PEEK T) as a replacement for commonly used UHMWPE and nitrided layer produced on Ti6Al4V titanium alloy using active screen plasma nitriding process.Amorphous carbon layer, 200nm thick, produced on PEEK composite significantly improved tribological properties of PEEK composite – TiN (nanocrystalline)+Ti2N+αTi(N) layer friction pair, decreasing the friction coefficient by 2 times and minimizing wear of both used materials in the point contact (“ball-on-disc” method) and in surface contact (“block-on-roll” method).

ОСЛОЖНЕНИЯ ПРИ ЭНДОПРОТЕЗИРОВАНИИ ТАЗОБЕДРЕННОГО СУСТАВА

Objective: To study the complications of hip joint endoprosthesis for congenital hip dislocation.Methods: The study included 62 patients, who performed hip joint endoprosthesis (HJE). Timing observations were from 2 to 12 years. Evaluation of the results was carried out on the basis of digital radiography, CT (according to indications), ultrasound sonography and electroneuromyography.Results: The results of operations performed were evaluated in terms of 3, 6, 12 months and, subsequently, every year. The functional result of the endoprosthesis was assessed deadlines according to the Harris scale. When analyzing the results, the following complications were revealed: profuse bleeding (1.7%), femur fracture (2.6%), fracture of the corpuscular acetabular layer (0.6%), sciatic neuropathy (3.1%) and femoral neuropathy (0.6%), loosening of the femoral component (1.7%), wear of polyethylene prosthesis (1.4%), phlebitis and thrombophlebitis of lower extremities (28.8%), resorption of autografts (27.4%).Conclusion: Complications with HJE are inevitable. However, their number can be controlled and reduced with sufficient experience. In general, complications with HJE did not significantly affect the results, because the total assessment of endoprosthesis by Harris was 86-92 points.Keywords: Hip joint, congenital hip dislocation, endoprosthesis, complication.

РЕЗУЛЬТАТЫ ТОТАЛЬНОГО ЭНДОПРОТЕЗИРОВАНИЯ ТАЗОБЕДРЕННОГО СУСТАВА ПРИ ВРОЖДЁННОМ ВЫВИХЕ БЕДРА

Objective: To study the results of total hip joint endoprosthesis for congenital hip dislocation.Methods: 62 patients (61 women and 1 man) with congenital hip dislocation performed hip joint endoprosthesis. The average age of the patients was 20.5 years (from 18 to 23 years). The survey included clinical and radiological methods of investigation. The technical features of surgical interventions are described.Results: Postoperative assessment of the results by the Harris scale was as follows: excellent (more than 85 points) in 21 (33.9%); good (more than 80 points) – 32 (51.6%), satisfactory (70-79 points) – 9 (14.5%) patients. The estimation of the offset centre of rotation of the head thigh bones, the protrusion of the prosthesis cup and the state bringing down thighs of the hip.Conclusion: Total hip replacement is the only effective method to treat congenital hip dislocation. The results of the executed operation point to the need for broad implementation of this method into clinical practice.Keywords: Hip joint, congenital hip dislocation, endoprosthesis.

Research of Time-Frequency Characteristics of Electrical Resistance Signal of Friction Zone of Hip Joint Endoprosthesis with Metal-Metal Friction Pair

In this paper, we propose spectral analysis methods to investigate the time-frequency characteristics of electrical signal from friction zone of a hip joint endoprosthesis with a metal-metal friction pair. They consist of a discrete Fourier transform (DFT) and a discrete wavelet transform (DWT). This complex method allows researching the time domain, the frequency domain, and the time-frequency domain characteristics of signals from friction zone in various ways. The results prove that the DFT and DWT (especially the wavelet scalogram) have great potential for the waveform analysis in order to detect the geometric (macro- and micro-) defects of the investigated implant.

Comparative Characteristic of Strength of Different Approaches to Cement Fixation of Therapeutic Component of Hip Joint in Endoprosthesis from Computer Modeling Positions

Improvement of cement consolidation technologies of the components of the hip joint endoprosthesis is carried out not only based on the analysis of clinical and X-ray data, but also by computer modeling. The purpose of the study was to study the stress-strain state of the virtual endoprosthetized hip joint with various variants of the acetabular cement anchoring. The finite element method was used as a theoretical basis. The ANSYS computer program was used to construct the desired model. For calculations, a version of the model, this includes three segments: the acetabular component, the cement mantle and the spongy bone was created.

Surgical treatment of secondary hip osteoarthritis using cementless total hip endoprosthesis with Fitmore® Hip Stem: A case report

Introduction. Hip dysplasia with subluxation represents insufficient coverage of the femur's head placed in the dysplastic acetabulum. This lack of coverage ranges from barely noticeable to condition where half of femur head is uncovered by acetabulum. The caput-collum-diaphyseal angle of the proximal femur and anteversion angle of collum are increased, Wiberg?s angle is less than 15? and M?nard-Shenton line is interrupted. Hip joint degeneration occurs very early. When radiological signs of hip joint degenerative changes are discovered in elderly they are associated with pain, limited movements and leg shortening. Case report. We present a 53-year old female treated conservatively in childhood because of hip diyplasia with subluxation. After pregnancy, right hip pain emerged. Clinical and radiological examinations revealed hip subluxation with the signs of degenerative osteoarthritis. Initial treatment was conservative and included drugs and balneophysical procedures. Since pain and movement impairment progressed and became constant, a hip replacement using cementless total endoprosthesis with Fitmore? Hip Stem was done. In the pre-operative preparation, anteroposterior x-ray of the hip(with third of the proximal femur) was made. This X-ray enabled precise planning of implantation endoprosthesis component. The early postoperative course was uneventful with very good therapeutic effect. Following successful physical rehabilitation, the patient returned to work and full life activity. Conclusion. Implantation of the cementless endoprosthesis with Fitmore? Hip Stem in the treatment of secondary hip osteoarthritis is a good choice in the treatment of young patients with good bone quality. Future clinical and radiological follow-up and comparative studies are needed to show the advantages of this type of stem compared to the classical cementless long stem.

FRETTING CORROSION OF COBALT AND TITANIUM IMPLANT ALLOYS IN SIMULATED BODY FLUIDS

The most important advantage of using modular hip joint endoprostheses is the possibility to adapt the endoprosthesis to the morphology and size of individual patients. However, the additional contact surface is subjected to fretting wear due to mutual micro displacements and the aggressive chemistry of the environment inside the human body (fretting corrosion). Today’s hip endoprostheses are generally composed of a hip stem, a femoral ball head and an acetabular cup (Figure 1). The hip stem is made of stainless steel, CoCrMo or a Ti alloys. The femoral ball head is made of stainless steel, CoCrMo, or a ceramic material. In the case of a modular hip stem, i.e. with a modular neck portion, the materials used are generally CoCrMo and Ti6Al 4V. (The interface between femoral ball head and the acetabular cup is an articulating surface and not the subject of this research project.) In this framework, a comparative study of the fretting corrosion resistance of the three most common metallic material combinations occurring in a modular, the non-articulating connection of total hip joint endoprostheses (CoCrMo-CoCrMo, CoCrMo-Ti6Al4V, and Ti6Al4V-Ti6Al4V) was undertaken. Studies were performed with a tribological tester, working in articulating-reciprocating motion, integrated with a potentiostat equipped with a tri-electrode system. The tribosystem consisted of a fixed stem pressed with a constant force to a plate performing the reciprocating motion of a predetermined frequency and amplitude. The tests were performed in diluted bovine serum at 37°C. Based on the obtained results, it was found that the greatest resistance to corrosion in static conditions was exhibited by the CoCrMo-CoCrMo friction pair, while the lowest ΔE value was obtained by CoCrMo-Ti6Al4V. It also confirmed the existence of a correlation between the intensity of the depassivation process caused by the mechanical destruction of the surface layer and the friction resistance values in the tribological system.

STAND FOR TRIBOLOGICAL TESTING OF HIP ENDOPROSTHESES

The paper presents a new construction of hip-joint simulator. The SBT-01.2 simulator is designed for conducting tribological testing of hip endoprostheses based on ISO 14242-1, which specifies the requirements for the range of motion and load characteristics of the friction pair (femoral head vs. acetabular cup) during one test cycle. The construction of the simulator is based on the anatomical structure of the human hip joint. The prosthesis acetabulum is mounted in the upper part of the mounting head while maintaining the inclination angle relative to the axis of the socket to the direction of the loading force. The head of the prosthesis is mounted on a pin embedded in the bottom, movable base. After placing a special sleeve on the lower base, liquid lubricant is applied on the head-cup tribological system. The employed software enables continuous control, online visualization, and data recording. During testing, parameters such as lubricant temperature, instantaneous loading force, friction torque, and the number of cycles are recorded.

Influence of Inclination Angle on the Polyethylene Insert Wear in Experimental Module of Hip Endoprosthesis

Localization and the area of polyethylene insert wear in friction pair ofthe experimental module of hip joint (HJ) endoprosthesis was studied under laboratory dynamic conditions simulating its biomechanics at HJ external rotation contracture. It was stated that localization and the area of wear depended on the angle of horizontal inclination infriction pair of HJ endoprosthesis. Almost the same areas of polyethylene wear in anterior and posterior insert segments were observed when inclination angle was equal to that of the hip joint. Reduction of inclination angle resulted in the increase of wear surface in the anterior segment and its decrease in the posterior one. Displacement of the wear zone into the anterior segment was accompanied by the reduction of total insert wear area. At repeated loadings it created conditions for the higher polyethylene insert wear.

THE STRUCTURAL ANALYSIS OF SOCKET INLAYS OF THE HIP ENDOPROSTHESIS

The paper presents results of the preliminary structural analysis of socket inlays model of the endoprosthesis of the hip joint. Basics of anatomy and biomechanical analysis of the hip joint were introduced. The prototype of socket inlay of the hip endoprosthesis was modeled using Solid Edge ST8 software. After determining physical properties of structural materials for socket inlays, the Finite Elements Analysis of the model was conducted using SolidWorks software under various load conditions. Finally the results of analysis were presented.

Influence of Inclination Angle on the Polyethylene Insert Wear in Experimental Module of Hip Endoprosthesis

Localization and the area of polyethylene insert wear in friction pair ofthe experimental module of hip joint (HJ) endoprosthesis was studied under laboratory dynamic conditions simulating its biomechanics at HJ external rotation contracture. It was stated that localization and the area of wear depended on the angle of horizontal inclination infriction pair of HJ endoprosthesis. Almost the same areas of polyethylene wear in anterior and posterior insert segments were observed when inclination angle was equal to that of the hip joint. Reduction of inclination angle resulted in the increase of wear surface in the anterior segment and its decrease in the posterior one. Displacement of the wear zone into the anterior segment was accompanied by the reduction of total insert wear area. At repeated loadings it created conditions for the higher polyethylene insert wear.

Comparison of Biocompatibility of Cemented vs. Cementless Hip Joint Endoprostheses Based on Postoperative Evaluation of Proinflammatory Cytokine Levels.

BackgroundThe yearly increase in the number of procedures involving implantation of hip joint endoprostheses forces prosthetics manufacturers to search for biologically neutral implants. The goal of this study was to assess the concentration of Interleukin-6 (IL-6) and its correlation with C-reactive protein (CRP), depending on the type of hip joint endoprosthesis (cemented or cementless endoprosthesis) in order to determine implant biotolerance during the early postoperative period.Material/MethodsThe sample comprised 200 patients [mean age=64 (31–81) years] with coxarthrosis. All patients underwent hip joint arthroplasty using a cemented or cementless endoprosthesis. Blood samples were collected 3 times: before the procedure, on the first day after the procedure, and after 6 weeks. IL-6 and CRP levels were assayed using immunoenzymatic methods. The results were subjected to statistical analysis using the Shapiro-Wilk test.ResultsOn the 1st day after the procedure, CRP and IL-6 concentration increased rapidly after implantation of both cemented and cementless endoprostheses. At 6 weeks postoperatively, the CRP value remained at a similar level in patients after cemented arthroplasty and was almost 2-fold lower in patients who underwent cementless arthroplasty. The IL-6 value returned to the baseline level in patients after cementless arthroplasty and showed an ongoing increasing tendency in patients after cemented arthroplasty.Conclusions1. The measurement of C-reactive protein and Interleukin-6 is a high-sensitivity test, assessing implant biotolerance. 2. The implantation of a cemented endoprosthesis induces a higher increase in the level of proinflammatory cytokines as compared with a cementless endoprosthesis. 3. For a complete assessment of both early and later body responses to implantation and the related surgical procedure, further studies using available approaches and tools are recommended.

Comparison of in vivo measured loads in knee, hip and spinal implants during level walking

Walking is a task that we seek to understand because it is the most relevant human locomotion. Walking causes complex loading patterns and high load magnitudes within the human body. This work summarizes partially published load data collected in earlier in vivo measurement studies on 9 patients with telemeterized knee endoprostheses, 10 with hip endoprostheses and 5 with vertebral body replacements. Moreover, for the 19 endoprosthesis patients, additional simultaneously measured and previously unreported ground reaction forces are presented.The ground reaction force and the implant forces in the knee and hip exhibited a double peak during each step. The maxima of the ground reaction forces ranged from 100% to 126% bodyweight. In comparison, the greatest implant forces in the hip (249% bodyweight) and knee (271% bodyweight) were much greater. The mean peak force measured in the vertebral body replacement was 39% bodyweight and occurred at different time points of the stance phase.We concluded that walking leads to high load magnitudes in the knee and hip, whereas the forces in the vertebral body replacement remained relatively low. This indicates that the first peak force was greater in the hip than in the knee joint while this was reversed for the second peak force. The forces in the spinal implant were considerably lower than in the knee and hip joints.

Are Higher Prices for Larger Femoral Heads in Total Hip Arthroplasty Justified from the Perspective of Health Care Economics? An Analysis of Costs and Effects in Germany

Background: In total hip arthroplasty (THA), femoral head diameter has not been regarded as a key parameter which should be restored when reconstructing joint biomechanics and geometry. Apart from the controversial discussion on the advantages and disadvantages of using larger diameter heads, their higher cost is another important reason that they have only been used to a limited extent. The goal of this study was to analyse the price structure of prosthetic heads in comparison to other components used in THA. A large group of patients with hip endoprostheses were evaluated with respect to the implanted socket diameter and thus the theoretically attainable head diameter. Materials and Methods: The relative prices of various THA components (cups, inserts, stems and ball heads) distributed by two leading German manufacturers were determined and analysed. Special attention was paid to different sizes and varieties in a series of components. A large patient population treated with THA was evaluated with respect to the implanted cup diameter and therefore the theoretically attainable head diameter. Results: The pricing analysis of the THA components of two manufacturers showed identical prices for cups, inserts and stems in a series. In contrast to this, the prices for prosthetic heads with a diameter of 36-44 mm were 11-50 % higher than for 28 mm heads. Identical prices for larger heads were the exception. The distribution of the head diameter in 2719 THA cases showed significant differences between the actually implanted and the theoretically attainable heads. Conclusion: There are proven advantages in using larger diameter ball heads in THA and the remaining problems can be solved. It is therefore desirable to correct the current pricing practice of charging higher prices for larger components. Instead, identical prices should be charged for all head diameters in a series, as is currently established practice for all other THA components. Thus when reconstructing biomechanics and joint geometry in THA, it should be possible to recover not only leg length, femoral offset and antetorsion of the femoral neck, but also to approximately restore the diameter of the femoral head and thereby optimise the functional outcome.

Plate fixation in periprosthetic femur fractures Vancouver type B1—Trochanteric hook plate or subtrochanterical bicortical locking?

IntroductionProximal plate fixation in periprosthetic femur fractures can be improved by plate anchorage in the greater trochanter (lateral tension band principle) or bicortical locking screw placement beside the prosthesis stem in an embracement configuration. Both concepts were compared in a biomechanical test using a femoral hook plate (hook) or a locking attachment plate (LAP). MethodsAfter bone mineral density (BMD) measurement in the greater trochanter, six pairs of fresh frozen human femora were assigned to two groups and instrumented with cemented hip endoprostheses. A transverse osteotomy was set distal to the tip of the prosthesis, simulating a Vancouver B1 fracture. Each pair was instrumented using a plate tensioner with either hook or LAP construct. Cyclic testing (2Hz) with physiologic profile and monotonically increasing load was performed until catastrophic failure. Plate stiffness was compared in a four-point-bending-test. Paired student’s-t-test was used for statistical evaluation (p<0.05). ResultsMean BMD was 250mgHA/ccm±47. The hook construct exhibited a significantly (p=0.015) lower number of cycles and load to failure (26′177cycles±2777; 3′118N±778) correlating significantly with BMD (R2=0.83; p=0.04) compared to the LAP construct (37′423cycles±5′299; 4′242N±1′030) (R2=0.71;p=0.11). BMD was a significant covariate (p=0.01). Plate stiffness was in a comparable range (hook Plate 468N/mm±7; LCP 445N/mm±6). ConclusionSubtrochanterically placed LAP provides an increased fixation strength under repetitive loading compared to hook plate fixation in the greater trochanter. Trochanteric fixation is highly BMD dependent and may be restricted to major greater trochanteric involvement requiring stabilization.

Analysis of the loads occurring in a modular hip joint endoprosthesis

Analysis of the loads occurring in a modular hip joint endoprosthesis

Use of Additive Techniques for Preparing Individual Components of Titanium Alloy Joint Endoprostheses

Additive techniques, particularly selective laser melting (SLM), allow devices of complex shape to be made from a variety of metallic materials. Preparation of individual large joint endoprosthesis components using digital techniques, i.e., computerized tomography, three-dimensional scanning, three-dimensional printing, and subsequent preparation of prostheses from titanium by SLM, allows patients’ individual anatomical features to be taken into account and implants to be personalized, thus improving endoprosthesis implantation results. The present article demonstrates that individual components of a hip joint endoprosthesis can be made using titanium alloy BT6 powder using the patient’s computerized tomography data.