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At least 469 records · Page 26Linked to original sources
PubMed1989

[Total hip prosthesis in bone loss of the femur].

Severe bone deficiency in total hip arthroplasty (THA) represents a serious problem, and there is an increasing demand for reconstructive measurements even on the femoral side to salvage these hips. The different therapeutical concepts are reviewed. Mechanical stability has proved to be of the utmost importance for successful results; fixation of the prosthesis by acrylic cement both in the graft and in the host femur seems to be superior to cementless fixation in most cases. The Wagner cementless self-locking revision stem has the advantage of facilitating regeneration in the deficient proximal femur without allografts and their disadvantages.

Bone Screws↗
PubMed1990

[The initial findings in 50 cases of the cementless hip prosthesis].

The authors, after putting forth several biomechanical premises, discuss their experience in total hip arthroplasty (THA) using a PCA-type press fit cementless prosthesis with partial Madreporic covering. Several cases which demonstrate the versatility of this type of replacement are discussed in depth. Even though the short follow-up precludes definitive conclusions, use of cementless total hip replacements must be considered a valid option in the future, especially in cases of early onset of hip pathology.

Adult↗
PubMed2001

Material optimization of femoral component of total hip prosthesis using fiber reinforced polymeric composites.

In this report an integrated approach to the three-dimensional material optimization of femoral components of hip prostheses is described. The effectiveness of using reinforced fiber composites for the material optimization of hip implants has been demonstrated and general guidelines on some material design aspects of total hip replacement (THR), in terms of fiber volume fraction and fiber orientation angles, are provided. A modular program was developed to interface the optimization routine with the finite element code. In this study two cases of cemented and non-cemented THR were investigated. In both cases perfectly bonded interfaces were assumed. Two objective functions were defined based on interface failure criteria and bone adaptive remodeling to avoid interface disruption and to reduce the risk of bone loss. The overall results demonstrated the effectiveness of the technique, which can provide meaningful insights into the fiber-reinforced composite material design of orthopaedic implants.

Benzophenones↗
PubMedDate not supplied

Position, orientation and component interaction in dislocation of the total hip prosthesis.

The position, orientation in space and interaction of prosthetic components was determined in 15 patients with known episodes of dislocation after total hip replacement. The same calculations were performed in a reference group of 44 patients without dislocation. In the group with dislocations, there was a significantly decreased femoral anteversion, and a decreased femoral flexion permitted by the prosthetic components. There were no further significant differences of clinical relevance between the groups concerning all other examined parameters of component position, orientation and interaction. It is concluded that the decreased range of flexion, caused by impingement of the prosthetic components with ensuing leverage effect is one cause of dislocation.

Aged↗
PubMed1995

[Total hip prosthesis with metal-on-metal slide matching--current developments based on long-term observations].

The first metal-on-metal artificial hip joints of the sixties (for example that of Mckee, Norwich) were soon replaced by models with polyethylene acetabular cups because of several shortcomings. 20 years later, however, a few patients were seen where such metal-to-metal joints still performed very well. Closer investigations revealed that with improved machining and a more perfect fit the failures of the first series could be eliminated and that these models were much less prone to wear than the ones using polyethylene. The author has developed and inserted such new prostheses, with good success so far.

Corrosion↗
PubMed2000

[Comparative evaluation of stress patterns in models of the normal hip joint and after implantation of the Parhofer-Mönch type hip prosthesis].

The paper presents a comparative appraisal of stress patterns of the normal acetabulum of the hip joint and after implantation of a Parhofer-Monch type prosthesis based on a computer simulation analysis. Three-dimensional physical models were constructed basing on finite element methods and loaded according to Pauwels' scheme with a force R = 2878 N. Mathematical analysis was performed on a computer equipped with a Pentium II processor, using professional software written for theory of elasticity problem solving. Equipotential stress patterns were designated according to Hubers' hypothesis. A redistribution and decrease in stress values in the bone directly around the acetabular component of the prosthesis was noted.

Acetabulum↗
PubMed1996

Migration and wear of a hydroxyapatite-coated hip prosthesis. A controlled roentgen stereophotogrammetric study.

A consecutive series of 30 total hip replacements using a hydroxyapatite (HA)-coated, modular implant (Omnifit) was followed clinically and by roentgen stereophotogrammetric analysis for two years and compared with two control groups, one of 27 cemented Charnley sockets and one of 40 cemented Charnley stems. Omnifit sockets with a central gap between the dome of the socket and the acetabular bone in the postoperative radiographs, migrated less than sockets without such gaps (p = 0.01). After adjustment for patient-related factors (age, gender and weight), no significant difference was found between the two prostheses with respect to micromotion and wear. We conclude that the early fixation of the HA-coated Omnifit prosthesis compares with that of the cemented Charnley prosthesis.

Adult↗
PubMed1987

The importance of trochanteric lag screws to achieve primary stability in cementless fixation of the RM hip prosthesis.

To allow the bony incorporation of a cementless prosthesis it is important to achieve stability at the time of operation. To neutralize tension and torsional stresses the RM-shaft prosthesis is fixed with two lag screws in the trochanteric part of the femur. By measuring the applied torque intraoperatively we could demonstrate that the threads of the screws found a better grip when inserted from the bone to the prosthesis. Thus, the stronger fixation of the screws enhanced the primary stability of the cementless prosthesis.

Bone Cements↗
PubMed2006

Socket wall addition device in the treatment of recurrent hip prosthesis dislocation: good outcome in 12 patients followed for 4.5 (1-9) years.

BACKGROUND: Recurrent dislocation in total hip replacement is difficult to treat and causes severe morbidity. PATIENTS AND METHODS: 12 patients suffering dislocations were reoperated with a socket wall addition device (anti-luxation ring) for the Lubinus SPII prosthesis, and were followed up after a mean of 4.5 (1-9) years with regard to redislocation, function and radiographic loosening. RESULTS: 1 of the patients suffered a redislocation after almost 7 years of use. There was no loosening during the follow-up time. A Harris hip score of 87 (60-100), a health-related quality of life (EQ-5D) index of 0.8 (0.6-1.0) and total range of motion of 145 degrees (125-165) indicate that the patients had a level of function comparable to that of age-matched hip surgery patients with no complications. INTERPRETATION: The anti-luxation ring shows promising mid-term results and seems to provide an alternative to more extensive revision surgery for selected patients.

Acetabulum↗
PubMed1993

In vivo corrosion of modular hip prosthesis components in mixed and similar metal combinations. The effect of crevice, stress, motion, and alloy coupling.

One hundred forty-eight retrieved modular hip prostheses of both mixed (Ti-6Al-4V/Co-Cr) and similar (Co-Cr/Co-Cr) metal combinations were examined and positive evidence of corrosive attack was found in the conical taper region between head and stem. Significant corrosion was observed in both mixed and similar metal combinations with 16% of necks and 35% of heads (for mixed-metal cases), and 14% of necks and 23% of heads (for similar-metal cases) showing moderate to severe corrosive attack. There was a significant correlation between the percentage of prostheses with moderate to severe corrosion and the duration of implantation for both mixed and similar metal cases, indicating that this corrosion process is progressive in time. Moderate to severe corrosion was seen as early as 2.5 and 11 months (mixed and similar metals, respectively). Scanning electron microscopy and x-ray analysis identified several forms of corrosive attack in the cobalt-based component of the taper. These included, for both mixed and same metal combinations: preferential dissolution of cobalt, fretting, and pitting; mixed metals only: the formation of a Ti-Cr-Mo interfacial phase and interdendritic corrosion; and for similar metals: intergranular attack adjacent to grain boundaries enriched in molybdenum and silicon. It is hypothesized that the restricted crevice environment, coupled with high cyclic stresses which cause repeated fracture of the passive oxide films in the taper, result in an unstable electrochemical environment within the crevice for both the cobalt alloy and Ti-alloy passive films. The passivity of these alloys is subsequently lost and active attack of the taper results. Also, the repeated fracturing of the passive films will result in large amounts of corrosion products being formed. This corrosion and particulate accumulation could result in loss of mechanical integrity of the implants in vivo, create particles for third body wear, and release particles into the surrounding tissues.

Alloys↗
PubMed2005

Serum interleukin 8 levels correlate with synovial fluid levels in patients with aseptic loosening of hip prosthesis.

Levels of inflammatory cytokines (tumor necrosis factor alpha, interleukin [IL] 6, and IL-8) in serum from patients with osteolysis on radiographs after hip arthroplasty [osteolysis(+), n = 28], patients without osteolysis after hip arthroplasty [osteolysis(-), n = 24], and nonoperated healthy subjects [controls, n = 20] were determined. In addition, cytokine levels in synovial fluid from patients undergoing revision total hip arthroplasty (n = 14) for loosening were measured and compared with each other and with the area of osteolysis on radiographs. Serum IL-6 and IL-8 levels were significantly higher in the osteolysis(+) group than in the osteolysis(-) or the control groups. Furthermore, a significant correlation was found between the serum and synovial fluid IL-8 levels and between synovial fluid IL-8 levels and the area of osteolysis in patients undergoing revision total hip arthroplasty. Therefore, serum IL-8 levels could be a useful periprosthetic osteolysis marker.

Female↗
PubMed1994

Morsellized allografts for fixation of the hip prosthesis femoral component. A mechanical and histological study in the goat.

To simulate femoral intramedullary bone stock loss in revision surgery of failed total hip arthroplasties, a method was developed using impacted trabecular bone grafts. In 14 goats a cemented total hip arthroplasty was performed, fixating the stem within a circumferential construction of bone allografts. After 6 or 12 weeks, 4 goats were used for mechanical tests and 3 for histology. The stability of the stems was determined in a loading experiment with roentgen-stereophotogrammetric analysis; loads of up to 1.44 times body weight were used. One aseptic loosening was seen with gross movements. In the other cases the most important movements were axial rotations (max. 0.24 degrees under 800 N) and axial translations (max. 0.16 mm under 800 N). After unloading some elastic recovery occurred. There were no differences between the 6 and 12-week groups. Histologically, revascularization and remodeling of the grafts were evident. Bone apposition and bone resorption of the grafts resulted in a mixture of graft and new bone. There was more new bone formation in the 12-week group, but the process was not yet completed. The use of impacted trabecular bone grafts in cases of severe intramedullary bone stock loss seems to be a promising revision technique.

Animals↗