This was a safety study where the hypothesis was that the newer-design CPCS femoral stem would demonstrate similar early clinical results and micromovement to the well-established Exeter stem. Both are collarless, tapered, polished cemented stems, the only difference being a slight lateral to medial taper with the CPCS stem. A total of 34 patients were enrolled in a single-blinded randomised controlled trial in which 17 patients received a dedicated radiostereometric CPCS stem and 17 a radiostereometric Exeter stem. No difference was found in any of the outcome measures pre-operatively or post-operatively between groups. At two years, the mean subsidence for the CPCS stem was nearly half that seen for the Exeter stem (0.77 mm (−0.943 to 1.77) and 1.25 mm (0.719 to 1.625), respectively; p = 0.032). In contrast, the mean internal rotation of the CPCS stem was approximately twice that of the Exeter (1.61° (−1.07° to 4.33°) and 0.59° (0.97° to 1.64°), respectively; p = 0.048). Other migration patterns were not significantly different between the stems. The subtle differences in designs may explain the different patterns of migration. Comparable migration with the Exeter stem suggests that the CPCS design will perform well in the long term.
The long-term effects of metal-on-metal arthroplasty are currently under scrutiny because of the potential biological effects of metal wear debris. This review summarises data describing the release, dissemination, uptake, biological activity, and potential toxicity of metal wear debris released from alloys currently used in modern orthopaedics. The introduction of risk assessment for the evaluation of metal alloys and their use in arthroplasty patients is discussed and this should include potential harmful effects on immunity, reproduction, the kidney, developmental toxicity, the nervous system and carcinogenesis.
This is the second of a series of reviews of registries. This review looks specifically at worldwide registry data that have been collected on knee arthroplasty, what we have learned from their reports, and what the limitations are as to what we currently know.
The June 2013 Hip &
Pelvis Roundup360 looks at: failure in metal-on-metal arthroplasty; minimal hip approaches; whether bisphosphonates improve femoral bone stock following arthroplasty; whether more fat means more operative time; surgical infection; vascularised fibular graft for osteonecrosis; subclinical SUFE; and dentists, hips and antibiotics.
We report a systematic review and meta-analysis
of published randomised and quasi-randomised trials evaluating the
efficacy of pre-operative skin antisepsis and cleansing techniques
in reducing foot and ankle skin flora. The post-preparation culture
number (Post-PCN) was the primary outcome. The data were evaluated
using a modified version of the Cochrane Collaboration’s tool. We
identified eight trials (560 participants, 716 feet) that met the inclusion
criteria. There was a significant difference in the proportions
of Post-PCN between hallux nailfold (HNF) and toe web spaces (TWS)
sites: 0.47 Meta-analyses showed that alcoholic chlorhexidine had better
efficacy than alcoholic povidone-iodine (PI) at HNF sites (risk
difference 0.19 (95% CI 0.08 to 0.30); p = 0.0005); a two-step intervention
using PI scrub and paint (S&
P) followed by alcohol showed significantly
better efficacy over PI (S&
P) alone at TWS sites (risk difference
0.13 (95% CI 0.02 to 0.24); p = 0.0169); and a two-step intervention
using chlorhexidine scrub followed by alcohol showed significantly
better efficacy over PI (S&
P) alone at the combined (HNF with
TWS) sites (risk difference 0.27 (95% CI 0.13 to 0.40); p <
0.0001).
No significant difference was found between cleansing techniques. Cite this article:
To review the current best surgical practice and detail a multi-disciplinary
approach that could further reduce joint replacement infection. Review of relevant literature indexed in PubMed.Objectives
Methods
Previous studies of failure mechanisms leading
to revision total knee replacement (TKR) performed between 1986 and
2000 determined that many failed early, with a disproportionate
amount accounted for by infection and implant-associated factors
including wear, loosening and instability. Since then, efforts have
been made to improve implant performance and instruct surgeons in
best practice. Recently our centre participated in a multi-centre evaluation
of 844 revision TKRs from 2010 to 2011. The purpose was to report
a detailed analysis of failure mechanisms over time and to see if
failure modes have changed over the past 10 to 15 years. Aseptic
loosening was the predominant mechanism of failure (31.2%), followed
by instability (18.7%), infection (16.2%), polyethylene wear (10.0%),
arthrofibrosis (6.9%) and malalignment (6.6%). The mean time to
failure was 5.9 years (ten days to 31 years), 35.3% of all revisions
occurred at less than two years, and 60.2% in the first five years.
With improvements in implant and polyethylene manufacture, polyethylene
wear is no longer a leading cause of failure. Early mechanisms of
failure are primarily technical errors. In addition to improving
implant longevity, industry and surgeons must work together to decrease
these technical errors. All reports on failure of TKR contain patients
with unexplained pain who not infrequently have unmet expectations.
Surgeons must work to achieve realistic patient expectations pre-operatively,
and therefore, improve patient satisfaction post-operatively. Cite this article:
An experimental rabbit model was used to test the null hypothesis,
that there is no difference in new bone formation around uncoated
titanium discs compared with coated titanium discs when implanted
into the muscles of rabbits. A total of three titanium discs with different surface and coating
(1, porous coating; 2, porous coating + Bonemaster (Biomet); and
3, porous coating + plasma-sprayed hydroxyapatite) were implanted
in 12 female rabbits. Six animals were killed after six weeks and
the remaining six were killed after 12 weeks. The implants with
surrounding tissues were embedded in methyl methacrylate and grinded
sections were stained with Masson-Goldners trichrome and examined
by light microscopy of coded sections.Objectives
Methods
Conventional amputation prostheses rely on the attachment of the socket to the stump, which may lead to soft-tissue complications. Intraosseous transcutaneous amputation prostheses (ITAPs) allow direct loading of the skeleton, but their success is limited by infection resulting from breaching of the skin at the interface with the implant. Keratinocytes provide the skin’s primary barrier function, while hemidesmosomes mediate their attachment to natural ITAP analogues. Keratinocytes must attach directly to the surface of the implant. We have assessed the proliferation, morphology and attachment of keratinocytes to four titaniumalloy surfaces in order to determine the optimal topography We have shown that the proliferation, morphology and attachment of keratinocytes are affected by the surface topography of the biomaterials used to support their growth. Smoother surfaces improved adhesion. We postulate that a smooth topography at the point of epithelium-ITAP contact could increase attachment
In an attempt to increase the life of cementless prostheses, an hydroxyapatite-coated implant which releases a bisphosphonate has been suggested as a drug-delivery system. Our Our findings demonstrated that zoledronate did not impair the proliferation of human osteoblasts when used at concentrations below 1 μ A concentration of 0.01% of titanium particles did not impair the proliferation of either cell line. Zoledronate affected the alkaline phosphatase activity of murine osteoblasts through a chelation phenomenon. The presence of titanium particles strongly decreased the alkaline phosphatase activity of murine osteoblasts. We did not detect any synergic effect of zoledronate and titanium particles on the behaviour of both human and murine osteoblasts.
Metal-on-metal (MoM) hip resurfacing was developed in the 1990s by surgeons in Birmingham, UK, as a surgical solution to the problem of osteoarthritis in younger, more active patients. Early results were promising and the procedure gained in popularity. However, adverse reports of soft-tissue reaction and failure started to appear from 2008 onwards. Surgeons may be asked to write medico-legal reports on the surgical aspects of an individual case for claimant lawyers or in defence for the NHSLA or indemnity insurers. The purpose of this article is to cover some of the aspects of the operation that may be considered in such medico-legal reports.
We report a systematic review and meta-analysis
of the peer-reviewed literature focusing on metal sensitivity testing
in patients undergoing total joint replacement (TJR). Our purpose
was to assess the risk of developing metal hypersensitivity post-operatively
and its relationship with outcome and to investigate the advantages
of performing hypersensitivity testing. We undertook a comprehensive search of the citations quoted in
PubMed and EMBASE: 22 articles (comprising 3634 patients) met the
inclusion criteria. The frequency of positive tests increased after
TJR, especially in patients with implant failure or a metal-on-metal
coupling. The probability of developing a metal allergy was higher
post-operatively (odds ratio (OR) 1.52 (95% confidence interval
(CI) 1.06 to 2.31)), and the risk was further increased when failed
implants were compared with stable TJRs (OR 2.76 (95% CI 1.14 to
6.70)). Hypersensitivity testing was not able to discriminate between
stable and failed TJRs, as its predictive value was not statistically
proven. However, it is generally thought that hypersensitivity testing
should be performed in patients with a history of metal allergy
and in failed TJRs, especially with metal-on-metal implants and
when the cause of the loosening is doubtful.
Endoprosthetic replacement of the pelvis is one of the most challenging types of limb-salvage surgery, with a high rate of complications. In an attempt to reduce this and build greater versatility into the reconstruction process, a new type of pelvic endoprosthesis was developed in 2003, based on the old McKee-Farrar prosthesis. This study reviews the outcomes in 27 patients who had an ice-cream cone pelvic prosthesis inserted at two different specialist bone tumour centres in the United Kingdom over the past six years. The indications for treatment included primary bone tumours in 19 patients and metastatic disease in two, and six implants were inserted following failure of a previous pelvic reconstruction. Most of the patients had a P2+P3 resection as classified by Enneking, and most had resection of the ilium above the sciatic notch. The mean age of the patients at operation was 49 years (13 to 81). Complications occurred in ten patients (37.0%), of which dislocation was the most common, affecting four patients (14.8%). A total of three patients (11.1%) developed a deep infection around the prosthesis but all were successfully controlled by early intervention and two patients (7.4%) developed a local recurrence, at the same time as widespread metastases appeared. In one patient the prosthesis was removed for severe pain. This method of treatment is still associated with high morbidity, but early results are promising. Complications are diminishing with increasing experience.
Lately, concerns have arisen following the use of large metal-on-metal bearings in hip replacements owing to reports of catastrophic soft-tissue reactions resulting in implant failure and associated complications. This review examines the literature and contemporary presentations on current clinical dilemmas in metal-on-metal hip replacement.
As metal-on-metal arthroplasty becomes more widespread, concerns are being raised about the potential dangers of metal particulate debris. We present the case of a benign psoas mass secondary to the presence of such particles. The mass was excised and the hip resurfacing subsequently revised to a total hip replacement.
We have examined the deterioration of implant fixation after withdrawal of parathyroid hormone (PTH) in rats. First, the pull-out force for stainless-steel screws in the proximal tibia was measured at different times after withdrawal. The stimulatory effect of PTH on fixation was lost after 16 days. We then studied whether bisphosphonates could block this withdrawal effect. Mechanical and histomorphometric measurements were conducted for five weeks after implantation. Subcutaneous injections were given daily. Specimens treated with either PTH or saline during the first two weeks showed no difference in the mechanical or histological results (pull-out force 76 N