Total Hip Prosthesis Research Articles

Asymptomatic Chronic Dislocation of a Cemented Total Hip Prosthesis

Dislocation of a total hip prosthesis is a painful and mentally stressful orthopaedic emergency.1 It may be long-standing and asymptomatic, typically involving the femoral portion.2–4 This report describes a peculiar chronic dislocation of both components of a total hip prosthesis. A 93-year-old female patient, thin and of short stature, had come to our attention for recent onset of lumbar pain at the orthopaedic department. She walked with significant unequal lengths of the lower limbs. She had previously been operated on for bilateral total hip replacement, in which the left hip, a Brunelli version (Brescia, Italy, 1977), was performed 30 years ago for dysplasia.5 At the emergency department, lumbar spine and pelvis radiographs were taken, showing scoliosis and vertebral arthrosic deformations, along with dislocation of both total left hip replacement components (Figure). It was detected that the femoral stem was loosened. Patient denied any fall injury or accident to the operated left hip. It was decided not to perform surgery because of the patient’s age. Many case reports have discussed hip dislocations in which a femoral component was involved. To our knowledge, this is the first case of dislocation of both prosthetic elements of a hip replacement that was completely asymptomatic while walking. Figure Bilateral hip prosthetization with dislocation of both prosthetic components of the left hip. This is a Brunelli THR version, peculiar for the squared and cemented socket. On the right is visible a color photo of an explanted cup. The cemented socket ...

Diagnostik und Therapie der Luxation nach Hüfttotalprothesenimplantation

Luxation following endoprosthetic hip replacement represents a frequent and severe complication and is the reason for a relevant number of hip arthroplasty revision interventions. The probability of occurrence of luxation of a total hip arthroplasty is associated with the indications, patient and operation-specific risk factors. Approximately 50% of luxations after total hip arthroplasty occur within 3 months of the operation (early luxation). The diagnostics of luxation of total hip arthroplasty are carried out by clinical and radiological methods. The causative assignment is made by assessment of joint stability, the bony situation (e.g. loosening, periprosthetic fracture and defects) and the soft tissue (e.g. pelvitrochanterian musculature). In cases of clinical and paraclinical signs of infection and of late luxations, a joint puncture is indicated. Therapy decisions are made depending on the cause (e.g. implant malpositioning, pelvitrochanterian insufficiency, impingement, incongruence between head and inlay and combinations of causes). Therapy of acute total hip prosthesis luxation begins with imaging controlled repositioning carried out with the patient under adequate analgesia and sedation. Conservative therapy is carried out by immobilization with a hip joint orthesis or pelvis-leg cast for 6 weeks. Operative therapy strategies for recurrent luxation are restoration of the correct implant position and sufficient soft tissue tension. Larger hip heads, bipolar heads and tripolar cups are more commonly used due to the geometrically lower probability of dislocation (higher jumping distance). Luxation of total hip prostheses due to infection is treated according to the principles of periprosthetic infection therapy. The rate of recurrence of luxation of 30% is high so that in cases of unsuccessful therapy treatment should best be carried out in a center for revision arthroplasty. The search for the exact cause of total hip prosthesis luxation is extremely important. A classification is only possible when the exact cause is known and together with patient and implant-specific details the therapeutic approach can be ascertained. In revision operations the intraoperative functional diagnostics must be exactly documented. The reasons for delayed luxations could be prosthesis infections, abrasion and loosening.

Reduction of metal artifacts from alloy hip prostheses in computer tomography.

The objective of this study was to evaluate the feasibility of reducing artifacts from large metal implants with gemstone spectral imaging (GSI) and metal artifact reduction software (MARS). Twenty-three in-vivo cobalt-chromium-molybdenum alloy total hip prostheses were prospectively scanned by fast kV-switching GSI between 80 and 140 kVp. The computed tomography images were reconstructed with monochromatic energy and with/without MARS. Both subjective and objective measurements were performed to assess the severity of metal artifacts. Increasing photon energy was associated with reduced metal artifacts in GSI images (P < 0.001). Combination of GSI with MARS further diminished the metal artifacts (P < 0.001). Artifact reduction at 3 anatomical levels (femoral head, neck, and shaft) were evaluated, with data showing that GSI and MARS could reduce metal artifacts at all 3 levels (P = 0.011, P < 0.001, and P = 0.003, respectively). Nevertheless, in certain cases, GSI without MARS produced more realistic images for the clinical situation. Proper usage of GSI with/without MARS could reduce the computed tomography artifacts of large metal parts and improve the radiological evaluation of postarthroplasty patients.

Result of a Minimum Five-Year Follow-Up of Hip Arthroplasty Using the Bencox® Hip Stem

Purpose: The purpose of this study is to report the results of artificial hip arthroplasty with minimum five-year follow-up using the Bencox (Corentec) hip stem, the first total hip prosthesis developed in Korea. Materials and Methods: We evaluated 27 hips in patients with femoral neck or intertrochanteric fracture (fracture group) and 58 hips in patients with arthritis or osteonecrosis of the femoral head (arthritis group) who underwent hip arthroplasty using a Bencox hip stem in combination with Bencox bipolar cup and Bencox acetabular cup between September 2006 and February 2008. Patients in the fracture group underwent bipolar hip arthroplasty, and those in the arthritis group underwent total hip arthroplasty. Results: During the follow-up period, there were no cases of revision of the femoral stem. Mean Harris hip score was 94 at the latest follow-up in (femoral neck or intertrochanteric) the fracture group, and improved from 57 preoperatively to 98 at the latest follow-up in the arthritis (or avascular necrosis) group. Radiographically, endosteal bone ongrowth was found in 23 of 27 cases in the fracture group (85.2%) and 56 of 58 cases in the arthritis group (96.6%). Stem loosening, infection, dislocation, and ceramic breakage were not noted. Conclusion: Clinical and radiographic evaluations of hip arthroplasty using the Bencox hip stem showed excellent outcomes with a minimum of five-year follow-up.

Tribological behavior of biomaterial for total hip prosthesis

Friction and wear plays an important role in determining the performance of biomaterials. To this end, the present research is carried out to understand the tribological behavior important biometallic alloy, Ti-6Al-4V under sliding contact. The friction and wear experiments were carried out using ball-on-disc and pin-on-disc tribometers in ambient air, under different conditions of normal applied loads (3, 6 and 10 N) and sliding speeds (1, 15 and 25 mm.s-1) for 3000 m. The obtained research results revealed the lowest coefficient of friction was 0.038 at 1 mm.s-1 and 3 N) while the higher value was in the range of 0.90 at 25 mm.s-1 and 3 N). Results show that the specimens have similar friction and wear performance, although the sliding speed and applied loads are different. The tribomechanical wear, as evident from the observation of abrasion, adhesion and cracking, is the predominant wear mechanism.

Dynamic contact analysis of total hip prosthesis during normal active walking cycle

The lifetime of the hip prosthesis is highly connected with the contact mechanism that occurs at the interface of the acetabular cup and femoral head. A three-dimensional acetabular component model is modelled to investigate the contact consequences for the different possible material combinations during the normal dynamic walking cycle. The different bearing couples considered for the analysis are metal in contact with plastic, metal on metal, metal on ceramic, ceramic on plastic, ceramic on metal and ceramic on ceramic combinations. The result reveals that the ceramic in contact with plastic i.e. alumina femoral head paired with Ultra-High Molecular Weight Polyethylene cup reduces the maximum von Mises stress and maximum contact pressure developed between the contacting interface when compared with other combinations. The finite element results are validated with the results of Jiang et al., and it is found to be high correlation of about 95% between the two results.

Tribological behavior of Ti-6Al-4V and Ti-6Al-7Nb Alloys for Total Hip Prosthesis

The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests consisted of measuring the weight loss and the friction coefficient of samples. The oscillating friction and wear tests have been carried out in ambient with oscillating tribotester in accordance with standards ISO 7148, ASTM G99-95a, and ASTM G133-95 under different conditions of normal loads (3, 6, and 10 N) and sliding speeds (1, 15, and 25 mm·s−1). As counter pairs, a 100Cr6 steel ball with 10 mm in diameter was used. Results show that the two alloys had similar friction and wear performance, although their grain structures and compositions are different. Occurrence of large frictional occurred, is probably caused by formation and periodic, localized fracture of a transfer layer. Higher friction with larger fluctuation and higher wear rate was observed at the higher siding speed. The Ti-6Al-4V wear mechanism transforms from ploughing and peeling off wear at low sliding speed to plastic deformation and adhesive wear.

Sonication as a Diagnostic Approach Used to Investigate the Infectious Etiology of Prosthetic Hip Joint Loosening

The purpose of the study was to evaluate the usefulness of sonication for the diagnosis of prosthetic joint infections (PJIs) by its comparison with periprosthetic tissues (PTs) and synovial fluid (SV-F) cultures. The study groups included 54 patients undergoing exchange of total hip prostheses for so called "aseptic" loosening occurring without clinical manifestations of an accompanying PJI and 22 patients who developed a sinus tract communicating with the prosthesis which was indicative of an ongoing infectious process. Significant positive culture results were obtained among 10 (18.5%) patients with "aseptic" implant failure and in 18 (81.8%) patients who developed a sinus tract. Sonicate-fluid (S-F) yielded bacterial growth in all culture-positive patients with "aseptic" loosening vs. 15 patients with presumed PJIs. There was a concordance in terms of bacterial species isolated from S-F and conventional cultures from individual patients. Coagulase-negative staphylococci were isolated most frequently. Sensitivity of sonication (75%) exceeded that estimated for PTs (69%) and SV-F (45%) cultures. We conclude that identification of causative agents of PJIs which is critical to further therapeutic decisions is aided by the combination of sonication and conventional culture.

Influence of the manufacturing process in performance concerning wear of total hip prostheses

Wear on joint prostheses is the leading cause of premature failure leading to revision surgery. Tests conducted on mechanical wear simulator show poor performance of prosthetic hip components manufactured using high-quality raw materials. Aiming to understand the phenomena that limit the longevity of joint prostheses, the manufacturing processes of two separate companies were investigated. Results obtained suggest that the lack of control during the manufacturing of the parts may be the reason for the low performance shown by the prostheses tested in the wear simulator. Out-of-roundness and roughness of finished surfaces is pointed out as the main manufacturing failure in production lines tested. Metal femoral heads showed deviations from roundness of up to 32.41 μm (σ = 8.869) and R a = 0.295 ± 0.03, while acetabular cups in ultra-high molecular weight polyethylene showed deviations of up to 166.31 μm (σ = 53.982) and R a = 0.031 ± 0.02. The out-of-roundness contributes to reducing the contact area between rolling surfaces, increasing tension in regions where premature wear on parts occurs with frequency. This study points out the common faults found in manufacturing processes and suggest changes to increase the longevity of total hip arthroplasty.

Applicazioni biotecnologiche nella Clinica Ortopedica di Padova

We usually apply the newest and more accepted biotechnological surgical treatments for bone regeneration. Our results are similar to those in the literature. At the same time, in our Bio-Orthopedics Laboratory, we are conducting studies and research mainly on two topics: bone tissue engineering and reactions to metal release from total hip prostheses. We present in this paper our ongoing research and the preliminary results.

Characterization of Staphylococcus epidermidis and Staphyloccocus warneri small-colony variants associated with prosthetic-joint infections

We determined the frequency of isolation of staphylococcal small-colony variants (SCVs) from 31 culture-positive patients undergoing revision of total hip prosthesis for aseptic loosening or presumed prosthetic-joint infection (PJI). We analysed auxotrophy of cultured SCVs, their antimicrobial susceptibility profiles and their biofilm-forming capacity. Eight SCV strains were cultivated from six (19 %) patients. All SCVs were coagulase-negative staphylococci (CNS) with Staphylococcus epidermidis as the predominant species; there was also one Staphylococcus warneri SCV. The SCVs were auxotrophic for haemin, with one strain additionally auxotrophic for menadione. We noted the presence of two phenotypically (differences concerning antimicrobial susceptibility) and genetically distinct SCV strains in one patient, as well as the growth of two genetically related SCVs that differed in terms of their morphology and the type of auxotrophy in another. Seven out of eight SCVs were resistant to meticillin and gentamicin. In addition, antibiotic sensitivity testing revealed three multidrug-resistant SCV-normal-morphology isolate pairs. One S. epidermidis SCV harboured icaADBC genes and was found to be a proficient biofilm producer. This paper highlights the involvement of CNS SCVs in the aetiology of PJIs, including what is believed to be the first report of a S. warneri SCV. These subpopulations must be actively sought in the routine diagnosis of implant-associated infections. Moreover, in view of the phenotypic and genetic diversity of some SCV pairs, particular attention should be paid to the investigation of all types of observed colony morphologies, and isolates should be subjected to antimicrobial susceptibility testing.

Huidige richtlijnen voor antibioticaprofylaxe bij patiënten met een gewrichtsprothese zijn niet volmaakt.

A haematogenous infection of a joint prosthesis is rare, but the consequences can be very serious. For that reason, guidelines issued by medical professional organizations for antibiotic prophylaxis in treatments which involve risk have long existed. On the basis of experience in the United States and the Netherlands, it is clear that successive guidelines sometimes contradict each other and are often not appropriately applied in daily practice. This may be due to insufficient clarity concerning the most important patient risk factors. It remains, for example, unclear when there is a question of reduced immunity in the patient and when the oral region has to be considered to be infected. An appeal is made to follow the existing guidelines better, and, if possible, to achieve a more multidisciplinary revision of the guidelines 'Total hip prosthesis, so that they would be more widely adhered to.

Biomechanical comparison of two angular stable plate constructions for periprosthetic femur fracture fixation

Fractures of the femur associated with total hip arthroplasty are a significant concern in orthopaedic and trauma surgery. However, little is known about the different biomechanical properties of internal fixation systems in combination with periprosthetic fractures. In this study two new internal fixation systems for periprosthetic fractures are investigated using a cadaver fracture model simulating a Vancouver B1 periprosthetic femur fracture. Nine pairs of fresh-frozen cadaver femurs were scanned by dual X-ray absorptiometry. Cementless total hip prostheses were implanted and a periprosthetic femur fracture was simulated. Fractures were randomly fixed either with the fixed angle locking attachment plate (LAP®, Depuy Synthes®, Solothurn, Switzerland) or the variable angle non-contact bridging plate (NCB®, Zimmer GmbH, Winterthur, Switzerland). Each construct was cyclically loaded to failure in axial compression. Axial stiffness and cycles to failure were significantly higher in the NCB group. Both systems were able to be fixed well around the femoral stem. The two different internal fixation systems for periprosthetic fractures differed significantly in our setup. The non-contact bridging plate system revealed significantly higher failure load and may be the preferred option where high stability and load capacity is needed right after operation.

Osteomalacia revealing Sjögren's syndrome: A case report

The most common renal disease in Sjögren's syndrome is tubulo-interstitial nephritis, responsible for tubular acidosis in around 20% of patients. Osteomalacia exceptionally occurs as the first manifestation of a renal tubule disorder due to a Sjögren's syndrome. By the way, we report a case of osteomalacia secondary to Sjögren's syndrome in a thirty one year old woman. This patient had hypothyroidism (Hashimoto's thyroiditis) and receives substitute treatment. She developed an osteomalacia with bilateral femoral neck fracture without traumatism. She had benefited from a total hip prosthesis. Another way, we found that renal tubular acidosis complicated from hypokalemic paralysis and bilateral nephrocalcinosis. This renal acidosis is due to Sjögren's syndrome. She was treated with corticosteroid, calcium and phosphorus with good clinical evolvement. During Sjögren's syndrome, osteomalacia can complicate the distal renal tubular acidosis. In spite of the rare cases of osteomalacia revealing Sjögren's syndrome, this auto-immune disease must appear in the list of the aetiologies of osteomalacia.

Crack Length Estimation from the Damage Modelisation around a Cavityi in the Orthopedic Cement of the Total Hip Prosthesis

In orthopedic surgery and particularly in the total hip arthroplasty, the stem fixation is performed in general using a surgical cement which consists essentially of polymer (PMMA). Fracture of cement and prosthesis loosening appears after a high-stress level. This phenomenon origin is due to the presence of micro-cavities in the PMMA volume. The focus of our study is the modeling using the finite-element method of the cement damage around these cavities, the cavities' sizes and shapes effect on the damage risk, and the crack length estimation due to this damage. A small Fortran schedule was incorporated with the Abaqus code to calculate the damage zone. Results show that the presence of a cavity in the cement increases the damage parameter. The damage appears when the cavity is located in cement on the loading axis. If the cavity changes its shape from circular to elliptical, the size of the damage zone increases. One can predict the initiation of a crack in cement with a maximal length of 70μm.Keywords: total hip prosthesis, crack, bone cement, biomechanics, damage.

Perspective on Hydroxyapatite-Coated Collars for Bone-Bridging

The Journal of Bone & Joint Surgery: September 4, 2013 - Volume 95 - Issue 17 - p e128 doi: 10.2106/JBJS.M.00525

Tribological behaviour of AISI 316L stainless steel for biomedical applications

The aim of this research is to study the tribological behaviour of AISI 316L stainless steel for surgical implants (total hip prosthesis). The tribological behaviour is evaluated by wear tests, using tribometers ball on disc and sphere on plane. These tests consisted of measuring the weight loss and the friction coefficient of stainless steel (SS) AISI 316L. The oscillating friction and wear tests have been carried out in ambient air with an oscillating tribotester in accord with standards ISO 7148, ASTM G99-95a and ASTM G133-95 under different conditions of normal applied load (3, 6 and 10 N) and sliding speed (1, 15 and 25 mm s−1). A ball of 100Cr 6, 10 mm in diameter, is used as counter pairs. These tribological results are compared with those carried out with a tribometer type pin on disc under different conditions of normal load applied P (19·43, 28 and 44 N) and sliding speed (600 and 1020 rev min−1). The behaviour observed for both samples suggests that the wear and friction mechanism during the tests is the same, and to increase the resistance to wear and friction of biomedical SS AISI 316L alloy used in total hip prosthesis (femoral stems), surface coating and treatment are necessary.

Arterial pseudoaneurysm as a false positive for infection in bone scintigraphy and with labeled leukocytes in a patient with total hip prosthesis

Arterial pseudoaneurysm as a false positive for infection in bone scintigraphy and with labeled leukocytes in a patient with total hip prosthesis

Pulmonary fat embolism

A 64-year-old man with a subcapital femoral fracture after falling with a scooter underwent a total hip prosthesis. Two days after surgery he developed sudden dyspnea and tachycardia, improved with the administration of supplemental oxygen at 2 liters per minute. Arterial blood gas analysis revealed a pO2 of 75 mmHg.

Improving Tribological Characteristics of Hip Prostheses Using Biocompatible Nanocoatings

Total hip prosthesis (THP) is the most success of the 20th century in orthopaedic biomedical engineering. However due to difficult conditions within the human body its durability is generally limited to 15-16 years. THP is a bio-tribosystem, on which many mechanical, thermal, chemical and biological factors act. This paper presents the results of an analysis regarding the topography and tribological parameters of femoral heads structures before and after TiN coating. We report on the synthesis of TiN thin films on steel substrates by pulsed laser deposition (PLD) method for improving the mechanical characteristics of the structures. Adhesion resistance of the coating on the sub-layer was evaluated by scratching tests accompanied by Optical Microscopy (OM), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). As a principal result, this work points out that TiN protective coatings deposited by PLD technique with the maximum number of pulses can represent an alternative technology to ensure adhesion and scratch resistance of TiN coatings on femoral heads.