Radiolucent lines and component stability in knee arthroplasty. Standard versus fluoroscopically-assisted radiographs. (1/2728)

The radiolucent lines and the stability of the components of 66 knee arthroplasties were assessed by six orthopaedic surgeons on conventional anteroposterior and lateral radiographs and on fluoroscopic views which had been taken on the same day. The examiners were blinded as to the patients and clinical results. The interpretation of the radiographs was repeated after five months. On fluoroscopically-assisted radiographs four of the six examiners identified significantly more radiolucent lines for the femoral component (p < 0.05) and one significantly more for the tibial implant. Five examiners rated more femoral components as radiologically loose on fluoroscopically-assisted radiographs (p = 0.0008 to 0.0154), but none did so for the tibial components. The mean intra- and interobserver kappa values were higher for fluoroscopically-assisted radiographs for both components. We have shown that fluoroscopically-assisted radiographs allow more reproducible, and therefore reliable, detection of radiolucent lines in total knee arthroplasty. Assessment of the stability of the components is significantly influenced by the radiological technique used. Conventional radiographs are not adequate for evaluation of the stability of total knee arthroplasty and should be replaced by fluoroscopically-assisted films.  (+info)

Analysis of 118 second-generation metal-on-metal retrieved hip implants. (2/2728)

Osteolysis is due to particulate wear debris and is responsible for the long-term failure of total hip replacements. It has stimulated the development of alternative joint surfaces such as metal-on-metal or ceramic-on-ceramic implants. Since 1988 the second-generation metal-on-metal implant Metasul has been used in over 60 000 hips. Analysis of 118 retrieved specimens of the head or cup showed rates of wear of approximately 25 microm for the whole articulation per year in the first year, decreasing to about 5 microm per year after the third. Metal surfaces have a 'self-polishing' capacity. Scratches are worn out by further joint movement. Volumetric wear was decreased some 60-fold compared with that of metal-on-polyethylene implants, suggesting that second-generation metal-on-metal prostheses may considerably reduce osteolysis.  (+info)

Migration of the Duraloc cup at two years. (3/2728)

We carried out 71 primary total hip arthroplasties using porous-coated, hemispherical press-fit Duraloc '100 Series' cups in 68 consecutive patients; 61 were combined with the cementless Spotorno stem and ten with the cemented Lubinus SP II stem. Under-reaming of 2 mm achieved a press-fit. Of the 71 hips, 69 (97.1%) were followed up after a mean of 2.4 years. Migration analysis was performed by the Ein Bild Rontgen Analyse method, with an accuracy of 1 mm. The mean total migration after 24 months was 1.13 mm. Using the definition of loosening as a total migration of 1 mm, it follows that 30 out of 63 cups (48%) were loose at 24 months.  (+info)

Survivorship and radiological analysis of the standard Souter-Strathclyde total elbow arthroplasty. (4/2728)

We undertook a radiological analysis of 186 standard Souter implants to determine survivorship and to analyse the pattern of failure in those needing revision. The implants had been inserted as a primary procedure in patients with rheumatoid arthritis of the elbow at our hospital over the last 12 years. Taking revision as an endpoint, the survivorship after 12 years was 87%. If, however, revision and loosening, defined as the Hindex value equivalent to demarcation of 1 mm around the whole implant, are also included, the survivorship falls to 80%. Of the 24 implants revised, 18 (75%) were for problems with the humeral component, three (12.5%) with the ulnar component and three (12.5%) for instability. Loosening of the humeral component occurred when the implant extended into the humerus, with the tip moving anteriorly on to the anterior humeral cortex. Our study indicates that loosening can be predicted by the rate of change in this angle of extension of the prosthesis.  (+info)

Cement migration after THR. A comparison of charnley elite and exeter femoral stems using RSA. (5/2728)

Studies using roentgen stereophotogrammetric analysis (RSA) have shown that the femoral components of cemented total hip replacements (THR) migrate distally relative to the bone, but it is not clear whether this occurs at the cement-implant or the cement-bone interface or within the cement mantle. Our aim was to determine where this migration occurred, since this has important implications for the way in which implants function and fail. Using RSA we compared for two years the migration of the tip of the stem with that of the cement restrictor for two different designs of THR, the Exeter and Charnley Elite. We have assumed that if the cement restrictor migrates, then at least part of the cement mantle also migrates. Our results have shown that the Exeter migrates distally three times faster than the Charnley Elite and at different interfaces. With the Exeter migration was at the cement-implant interface whereas with the Charnley Elite there was migration at both the cement-bone and the cement-implant interfaces.  (+info)

Subsidence of a non-polished stem in revisions of the hip using impaction allograft. Evaluation with radiostereometry and dual-energy X-ray absorptiometry. (6/2728)

We revised 24 consecutive hips with loosening of the femoral stem using impaction allograft and a cemented stem with an unpolished proximal surface. Repeated radiostereometric examinations for up to two years showed a slow rate of subsidence with a mean of 0.32 mm (-2.0 to +0.31). Fifteen cases followed for a further year showed the same mean subsidence after three years, indicating stabilisation. A tendency to retroversion of the stems was noted between the operation and the last follow-up. Retroversion was also recorded when displacement of the stem was studied in ten of the patients after two years. Repeated determination of bone mineral density showed an initial loss after six months, followed by recovery to the postoperative level at two years. Defects in the cement mantle and malalignment of the stem were often noted on postoperative radiographs, but did not correlate with the degrees of migration or displacement. After one year, increasing frequency of trabecular remodelling or resorption of the graft was observed in the greater trochanter and distal to the tip of the stem. Cortical repair was noted distally and medially (Gruen regions 3, 5 and 6). Migration of the stems was the lowest reported to date, which we attribute to the improved grafting technique and to the hardness of the graft.  (+info)

Induction of macrophage C-C chemokine expression by titanium alloy and bone cement particles. (7/2728)

Particulate wear debris is associated with periprosthetic inflammation and loosening in total joint arthroplasty. We tested the effects of titanium alloy (Ti-alloy) and PMMA particles on monocyte/macrophage expression of the C-C chemokines, monocyte chemoattractant protein-1 (MCP-1), monocyte inflammatory protein-1 alpha (MIP-1alpha), and regulated upon activation normal T expressed and secreted protein (RANTES). Periprosthetic granulomatous tissue was analysed for expression of macrophage chemokines by immunohistochemistry. Chemokine expression in human monocytes/macrophages exposed to Ti-alloy and PMMA particles in vitro was determined by RT-PCR, ELISA and monocyte migration. We observed MCP-1 and MIP-1alpha expression in all tissue samples from failed arthroplasties. Ti-alloy and PMMA particles increased expression of MCP-1 and MIP-1alpha in macrophages in vitro in a dose- and time-dependent manner whereas RANTES was not detected. mRNA signal levels for MCP-1 and MIP-1alpha were also observed in cells after exposure to particles. Monocyte migration was stimulated by culture medium collected from macrophages exposed to Ti-alloy and PMMA particles. Antibodies to MCP-1 and MIP-1alpha inhibited chemotactic activity of the culture medium samples. Release of C-C chemokines by macrophages in response to wear particles may contribute to chronic inflammation at the bone-implant interface in total joint arthroplasty.  (+info)

Cytokine levels in synovial fluid from hips with well-functioning or loose prostheses. (8/2728)

We analysed synovial fluid from 88 hips, 38 with osteoarthritis and 12 with well-functioning and 38 with loose hip prostheses. The levels of TNF-alpha, IL-1beta (71 hips) and IL-6 (45 hips) were measured using the ELISA technique. Joints with well-functioning or loose prostheses had significantly increased levels of TNF-alpha compared with those with osteoarthritis. Hips with aseptic loosening also had higher levels of IL-1beta but not of IL-6 compared with those without an implant. The levels of TNF-alpha and IL-1beta did not differ between hips with stable and loose prostheses. Higher levels of TNF-alpha were found in hips with bone resorption of type II and type III (Gustilo-Pasternak) compared with those with type-I loosening. The level of cytokines in joint fluid was not influenced by the time in situ of the implants or the age, gender or area of the osteolysis as measured on conventional radiographs. Our findings support the theory that macrophages in the joint capsule increase the production of TNF-alpha at an early phase probably because of particle load and in the absence of clinical loosening. Since TNF-alpha has an important role in the osteolytic process, the interfaces should be protected from penetration of joint fluid.  (+info)