FIN and osteotomies

10.1007/978-3-642-03031-4_24Flexible Intramedullary Nailing in Children: The Nancy University Manual301-30

Comparative study of material loss at the taper interface in retrieved metal-on-polyethylene and metal-on-metal femoral components from a single manufacturer

There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25?mm3 with the consequent median value for metal-on-metal taper loss being 1.75?mm3. This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59?mm3. Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery. AB - There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25?mm3 with the consequent median value for metal-on-metal taper loss being 1.75 mm3. This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59 mm3. Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery

The Role of Metal-on-Metal Bearings in Total Hip Arthroplasty and Hip Resurfacing: Review Article

BACKGROUND: The current role of metal-on-metal (MoM) bearings in hip arthroplasty remains controversial. The low wear offered by MoM bearings compared to metal-on-polyethylene and the possibility of a lower risk of dislocation with larger head sizes, encouraged a trend towards the re-introduction of the MoM bearing couple. However, recent evidence has shown that not all designs of the MoM bearing have been successful. QUESTIONS/PURPOSES: The purpose of this paper is to provide an update on the use of MoM bearings and address the following issues: (1) the reintroduction of metal-on-metal bearings in total hip arthroplasty, (2) the failure of metal-on-metal bearings in stemmed total hip arthroplasty, (3) the role of metal-on-metal hip resurfacing in modern orthopaedics and (4) metal-on-metal hip resurfacing versus total hip arthroplasty. METHODS: A literature search strategy was conducted using various search terms in MEDLINE and Embase. The highest quality articles that met the inclusion criteria and best answered the topics of focus of this review were selected. Key search terms included ‘metal-on-metal’, ‘total hip arthroplasty’ and ‘hip resurfacing’. RESULTS: The initial search retrieved 1240 articles. Twenty-two articles were selected and used in the review. CONCLUSION: Metal-on-metal hip resurfacing is still a suitable treatment option in specific patient populations with the appropriate implant design and surgical skill, while stemmed metal-on-metal total hip arthroplasty should be avoided in all patient populations. Continued follow-up of patients undergoing metal-on-metal hip resurfacing is critical in order to further understand the long-term outcomes of these patients and why certain complications tend to occur with this procedure. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11420-016-9521-9) contains supplementary material, which is available to authorized users

Are abductor muscle quality and previous revision surgery predictors of constrained liner failure in hip arthroplasty?

Dislocation is one of the most common complications of total hip arthroplasty. The use of constrained liners is an option for the management of chronic hip instability, typically used after other methods have failed. The purposes of this study were to evaluate the overall clinical outcomes and failure rates of a tripolar constrained liner design, to assess the radiographic outcomes of its use, and to examine whether various factors such as abductor mechanism quality and history of previous revision surgeries were associated with an increased risk of failure. Forty-three hips in 39 patients who had a mean follow-up of 51 months (range, 24–110 months) were reviewed. Ninety-one percent of the hips (39 of 43 hips) did not need any revisions over the study period. A new liner was implanted in all four failed hips with concurrent revision of the acetabular cup in three cases. No further dislocations occurred in this group. The mean hip score for surviving hips was 82 points (range, 38–100 points) at final follow-up. Radiographic evaluation revealed stable, well-fixed acetabular components in all surviving hips without progressive radiolucencies. No association was found between abductor muscle quality and the incidence of failure, but patients who experienced a constrained liner failure were more likely to have undergone at least one previous hip revision operation. Tripolar constrained acetabular liners can provide successful outcomes in patients with hip instability, although it is important not to rely on the use of a constrained liner alone in an attempt to compensate for other correctable factors such as component positioning

Biomechanical concept and clinical outcome of dual mobility cups.

Dual mobility cup systems in total hip arthroplasty consist of a metal back with a non-constrained liner, in which a constrained standard head articulates. While superior stability of such implants in comparison with standard total hip replacements is assumed, it is the purpose of this study to outline the biomechanical concept of dual mobility cups and to describe implant survival and dislocation rate based on the series published in the English-speaking and Francophone literature. A growing body of evidence indicates reduced dislocation rates in primary and revision total hip arthroplasty and in selected tumour cases. The limited availability of studies evaluating long-term implant survival and existing concerns with regard to increased wear rates and aseptic loosening, leads to the conclusion that such implants have to be used with prudence, particularly in standard primary hip arthroplasty and in young patients