The October 2014 Research Roundup360 looks at: unpicking syndesmotic injuries: CT scans evaluated; surgical scrub suits and sterility in theatre; continuous passive motion and knee injuries; whether pain at night is melatonin related;
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.
Intermittently administered parathyroid hormone (PTH 1-34) has been shown to promote bone formation in both human and animal studies. The hormone and its analogues stimulate both bone formation and resorption, and as such at low doses are now in clinical use for the treatment of severe osteoporosis. By varying the duration of exposure, parathyroid hormone can modulate genes leading to increased bone formation within a so-called ‘anabolic window’. The osteogenic mechanisms involved are multiple, affecting the stimulation of osteoprogenitor cells, osteoblasts, osteocytes and the stem cell niche, and ultimately leading to increased osteoblast activation, reduced osteoblast apoptosis, upregulation of Wnt/β-catenin signalling, increased stem cell mobilisation, and mediation of the RANKL/OPG pathway. Ongoing investigation into their effect on bone formation through ‘coupled’ and ‘uncoupled’ mechanisms further underlines the impact of intermittent PTH on both cortical and cancellous bone. Given the principally catabolic actions of continuous PTH, this article reviews the skeletal actions of intermittent PTH 1-34 and the mechanisms underlying its effect.
The cytotoxicity induced by cobalt ions (Co2+) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co2+ and Co-NPs on liver cells, and explain further the potential mechanisms. Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co2+ or Co-NPs treatment.Objectives
Methods
Compartment syndrome results from increased intra-compartmental
pressure (ICP) causing local tissue ischaemia and cell death, but
the systemic effects are not well described. We hypothesised that
compartment syndrome would have a profound effect not only on the affected
limb, but also on remote organs. Using a rat model of compartment syndrome, its systemic effects
on the viability of hepatocytes and on inflammation and circulation
were directly visualised using intravital video microscopy.Aims
Methods
This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris.Objectives
Methods
There is increasing global awareness of adverse
reactions to metal debris and elevated serum metal ion concentrations
following the use of second generation metal-on-metal total hip
arthroplasties. The high incidence of these complications can be
largely attributed to corrosion at the head-neck interface. Severe
corrosion of the taper is identified most commonly in association
with larger diameter femoral heads. However, there is emerging evidence
of varying levels of corrosion observed in retrieved components
with smaller diameter femoral heads. This same mechanism of galvanic
and mechanically-assisted crevice corrosion has been observed in
metal-on-polyethylene and ceramic components, suggesting an inherent
biomechanical problem with current designs of the head-neck interface. We provide a review of the fundamental questions and answers
clinicians and researchers must understand regarding corrosion of
the taper, and its relevance to current orthopaedic practice. Cite this article:
We prospectively assessed the efficacy of a ceramic-on-metal
(CoM) hip bearing with uncemented acetabular and femoral components
in which cobalt–chrome acetabular liners and alumina ceramic heads
were used. The cohort comprised 94 total hip replacements (THRs) in 83 patients
(38 women and 45 men) with a mean age of 58 years (42 to 70). Minimum
follow-up was two years. All patients had pre- and post-operative
assessment using the Western Ontario and McMaster Universities osteoarthritis
index (WOMAC), Oxford hip score and Short-Form 12 scores. All showed
a statistically significant improvement from three months post-operatively
onwards (all p <
0.001). After two years whole blood metal ion levels were measured and
chromosomal analysis was performed. The levels of all metal ions
were elevated except vanadium. Levels of chromium, cobalt, molybdenum
and titanium were significantly higher in patients who underwent
bilateral THR compared with those undergoing unilateral THR (p <
0.001).
Chromosomal analysis demonstrated both structural and aneuploidy
mutations. There were significantly more breaks and losses than
in the normal population (p <
0.001). There was no significant
difference in chromosomal aberration between those undergoing unilateral
and bilateral procedures (all analyses p ≥ 0.62). The use of a CoM THR is effective clinically in the short-term,
with no concerns, but the significance of high metal ion levels
and chromosomal aberrations in the long-term remains unclear. Cite this article:
A 70-year-old man with an uncemented metal-on-polyethylene
total hip prosthesis underwent revision arthroplasty 33 months later
because of pain, swelling and recurrent dislocation. There appeared
to be corrosion and metal release from the prosthetic head, resulting
in pseudotumour formation and severe local soft-tissue destruction.
The corrosion occurred at the junction between the titanium-molybdenum-zirconium-iron
taper and the cobalt-chrome-molybdenum head, but the mechanism was unproven.
Satisfactory primary wound healing following
total joint replacement is essential. Wound healing problems can
have devastating consequences for patients. Assessment of their healing
capacity is useful in predicting complications. Local factors that
influence wound healing include multiple previous incisions, extensive
scarring, lymphoedema, and poor vascular perfusion. Systemic factors
include diabetes mellitus, inflammatory arthropathy, renal or liver
disease, immune compromise, corticosteroid therapy, smoking, and
poor nutrition. Modifications in the surgical technique are necessary
in selected cases to minimise potential wound complications. Prompt
and systematic intervention is necessary to address any wound healing
problems to reduce the risks of infection and other potential complications. Cite this article:
Animal models have been developed that allow simulation of post-traumatic joint contracture. One such model involves contracture-forming surgery followed by surgical capsular release. This model allows testing of antifibrotic agents, such as rosiglitazone. A total of 20 rabbits underwent contracture-forming surgery. Eight weeks later, the animals underwent a surgical capsular release. Ten animals received rosiglitazone (intramuscular initially, then orally). The animals were sacrificed following 16 weeks of free cage mobilisation. The joints were tested biomechanically, and the posterior capsule was assessed histologically and via genetic microarray analysis.Aims
Methods
We present a series of 35 patients (19 men and
16 women) with a mean age of 64 years (36.7 to 75.9), who underwent
total hip replacement using the ESKA dual-modular short stem with
metal on-polyethylene bearing surfaces. This implant has a modular
neck section in addition to the modular head. Of these patients,
three presented with increasing post-operative pain due to pseudotumour
formation that resulted from corrosion at the modular neck-stem
junction. These patients underwent further surgery and aseptic lymphocytic
vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the
neck-stem taper. Blood cobalt and chromium levels were measured
at a mean of nine months (3 to 28) following surgery. These were
compared with the levels in seven control patients (three men and
four women) with a mean age of 53.4 years (32.1 to 64.1), who had
an identical prosthesis and articulation but with a prosthesis that
had no modularity at neck-stem junction. The mean blood levels of
cobalt in the study group were raised at 50.75 nmol/l (5 to 145)
compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important
source of metal ion release and pseudotumour formation requiring
revision surgery. Finite element modelling of the dual modular stem
demonstrated high stresses at the modular stem-neck junction. Dual
modular cobalt-chrome hip prostheses should be used with caution
due to these concerns.
A modular femoral head–neck junction has practical
advantages in total hip replacement. Taper fretting and corrosion
have so far been an infrequent cause of revision. The role of design
and manufacturing variables continues to be debated. Over the past
decade several changes in technology and clinical practice might
result in an increase in clinically significant taper fretting and
corrosion. Those factors include an increased usage of large diameter
(36 mm) heads, reduced femoral neck and taper dimensions, greater
variability in taper assembly with smaller incision surgery, and
higher taper stresses due to increased patient weight and/or physical
activity. Additional studies are needed to determine the role of
taper assembly compared with design, manufacturing and other implant
variables. Cite this article:
Recently, the use of metal-on-metal articulations
in total hip arthroplasty (THA) has led to an increase in adverse
events owing to local soft-tissue reactions from metal ions and
wear debris. While the majority of these implants perform well,
it has been increasingly recognised that a small proportion of patients
may develop complications secondary to systemic cobalt toxicity
when these implants fail. However, distinguishing true toxicity
from benign elevations in cobalt ion levels can be challenging. The purpose of this two part series is to review the use of cobalt
alloys in THA and to highlight the following related topics of interest:
mechanisms of cobalt ion release and their measurement, definitions
of pathological cobalt ion levels, and the pathophysiology, risk factors
and treatment of cobalt toxicity. Historically, these metal-on-metal
arthroplasties are composed of a chromium-cobalt articulation. The release of cobalt is due to the mechanical and oxidative
stresses placed on the prosthetic joint. It exerts its pathological
effects through direct cellular toxicity. This manuscript will highlight the pathophysiology of cobalt
toxicity in patients with metal-on-metal hip arthroplasties. Take home message: Patients with new or evolving hip symptoms
with a prior history of THA warrant orthopaedic surgical evaluation.
Increased awareness of the range of systemic symptoms associated
with cobalt toxicity, coupled with prompt orthopaedic intervention, may
forestall the development of further complications. Cite this article:
Healing in cancellous metaphyseal bone might be different from
midshaft fracture healing due to different access to mesenchymal
stem cells, and because metaphyseal bone often heals without a cartilaginous
phase. Inflammation plays an important role in the healing of a
shaft fracture, but if metaphyseal injury is different, it is important
to clarify if the role of inflammation is also different. The biology
of fracture healing is also influenced by the degree of mechanical
stability. It is unclear if inflammation interacts with stability-related
factors. We investigated the role of inflammation in three different models:
a metaphyseal screw pull-out, a shaft fracture with unstable nailing
(IM-nail) and a stable external fixation (ExFix) model. For each,
half of the animals received dexamethasone to reduce inflammation,
and half received control injections. Mechanical and morphometric evaluation
was used.Objectives
Methods
We studied 51 patients with osteo-articular tuberculosis who were divided into two groups. Group I comprised 31 newly-diagnosed patients who were given first-line antituberculous treatment consisting of isoniazid, rifampicin, ethambutol and pyrazinamide. Group II (non-responders) consisted of 20 patients with a history of clinical non-responsiveness to supervised uninterrupted antituberculous treatment for a minimum of three months or a recurrence of a previous lesion which on clinical observation had healed. No patient in either group was HIV-positive. Group II were treated with an immunomodulation regime of intradermal BCG, oral levamisole and intramuscular diphtheria and tetanus vaccines as an adjunct for eight weeks in addition to antituberculous treatment. We gave antituberculous treatment for a total of 12 to 18 months in both groups and they were followed up for a mean of 30.2 months (24 to 49). A series of 20 healthy blood donors served as a control group. Twenty-nine (93.6%) of the 31 patients in group I and 14 of the 20 (70%) in group II had a clinicoradiological healing response to treatment by five months. The CD4 cell count in both groups was depressed at the time of enrolment, with a greater degree of depression in the group-II patients (686 cells/mm3 (
We investigated the clinical response to arthroscopic
synovectomy in patients with undifferentiated chronic monoarthritis
(UCMA) of the wrist. Arthroscopic synovectomy was performed on 20
wrists in 20 patients with UCMA of the wrist who had not responded
to non-steroidal anti-inflammatory drugs. The mean duration of symptoms
at the time of surgery was 4.3 months (3 to 7) and the mean follow-up
was 51.8 months (24 to 94). Inflamed synovium was completely removed
from the radiocarpal, midcarpal and distal radioulnar joints using
more portals than normal. After surgery, nine patients had early
remission of synovitis and 11 with uncontrolled synovitis received
antirheumatic medication. Overall, there was significant improvement
in terms of pain relief, range of movement and Mayo score. Radiological
deterioration was seen in five patients who were diagnosed as having rheumatoid
arthritis during the follow-up period. Lymphoid follicles and severe
lymphocyte infiltration were seen more often in synovial biopsies
from patients with uncontrolled synovitis. These results suggest that arthroscopic synovectomy provides
pain relief and functional improvement, and allows rapid resolution
of synovitis in about half of patients with UCMA of the wrist.
This paper considers the increased risk of the development of lymphoma in patients with chronic inflammatory disease who undergo metal-on-metal arthroplasty.
The LockDown device (previously called Surgilig)
is a braided polyester mesh which is mostly used to reconstruct the
dislocated acromioclavicular joint. More than 11 000 have been implanted
worldwide. Little is known about the tissue reaction to the device
nor to its wear products when implanted in an extra-articular site
in humans. This is of importance as an adverse immunological reaction
could result in osteolysis or damage to the local tissues, thereby affecting
the longevity of the implant. We analysed the histology of five LockDown implants retrieved
from five patients over the last seven years by one of the senior
authors. Routine analysis was carried out in all five cases and
immunohistochemistry in one. The LockDown device acts as a scaffold for connective tissue
which forms an investing fibrous pseudoligament. The immunological
response at the histological level seems favourable with a limited
histiocytic and giant cell response to micron-sized wear particles.
The connective tissue envelope around the implant is less organised
than a native ligament. Cite this article: