Femoral revision knee Arthroplasty with Metaphyseal sleeves: the use of a stem is not mandatory of a structural point of view

PURPOSE

Although metaphyseal sleeves are usually used with stems, little is known about the exact contribution/need of the stem for the initial sleeve-bone interface stability, particularly in the femur, if the intramedullary canal is deformed or bowed. The aim of the present study is (1) to determine the contribution of the diaphyseal-stem on sleeve-femur interface stability and (2) to determine experimentally the strain shielding effect on the metaphyseal femur with and without diaphyseal-stem. It is hypothesised that diaphyseal-stem addition increases the sleeve-femur interface stability and the strain-shielding effect on the metaphyseal femur relatively to the stemless condition.

MATERIAL AND METHODS

The study was developed through a combined experimental and finite-element analysis approach. Five synthetic femurs were used to measure cortex strain (triaxial-rosette-gages) behaviour and implant cortex micromotions (Digital Image Correlation) for three techniques: only femoral-component, stemless-sleeve and stemmed-sleeve. Paired t-tests were performed to evaluate the statistical significance of the difference of cortex strains and micromotions. Finite-element models were developed to assess the cancellous bone strain behaviour and sleeve-bone interface micromotions; these models were validated against the measurements.

RESULTS

Cortex strains are significantly reduced (p < 0.05) on the stemmed-sleeve with a 150 μstrain mean reduction at the medial and lateral distal sides which compares with a 60 μstrain mean reduction (p > 0.05) on the stemless condition. Both techniques presented a mean cancellous bone strain reduction of 700 μstrain (50%) at the distal region and a mean increase of 2500 μstrain (4x) at the sleeve proximal region relative to the model only with the femoral component. Both techniques presented sleeve-bone micromotions amplitude below 50-150 μm, suitable for bone ingrowth.

CONCLUSIONS

The use of a supplemental diaphyseal-stem potentiates the risk of cortex bone resorption as compared to the stemless-sleeve condition; however, the stem is not essential for the enhancement of the initial sleeve-bone stability and has minor effect on the cancellous bone strain behaviour. Based on a purely structural point view, it appears that the use of a diaphyseal-femoral-stem with the metaphyseal sleeve is not mandatory in the revision TKA, which is particularly relevant in cases where the use of stems is impracticable.

SARS-CoV-2 in Spanish Intensive Care Units: Early experience with 15-day survival in Vitoria

Purpose

Community transmission of SARS-CoV-2 was detected in Spain in February 2020, with 216% intensive care unit (ICU) capacity expanded in Vitoria by March 18^th, 2020.

Methods

We identified patients from the two public hospitals in Vitoria who were admitted to ICU with confirmed infection by SARS-CoV-2. Data reported here were available in April 6th, 2020. Mortality was assessed in those who completed 15-days of ICU stay.

Results

We identified 48 patients (27 males) with confirmed SARS-CoV-2. Median [interquartile range (IQR)] age of patients was 63 [51–75] years. Symptoms began a median of 7 [5–12] days before ICU admission. The most common comorbidities identified were obesity (48%), arterial hypertension (44%) and chronic lung disease (37%). All patients were admitted by hypoxemic respiratory failure and none received non-invasive mechanical ventilation. Forty-five (94%) underwent intubation, 3 (6%) high flow nasal therapy (HFNT), 1 (2%) extracorporeal membrane oxygenation (ECMO) and 22 (46%) required prone position. After 15 days, 14/45 (31%) intubated patients died (13% within one week), 10/45 (22%) were extubated, and 21/45 (47%) underwent mechanical ventilation. Six patients had documented super-infection. Procalcitonin plasma above 0.5 μg/L was associated with 16% vs. 19% (p = 0.78) risk of death after 7 days.

Conclusion

This early experience with SARS-CoV-2 in Spain suggests that a strategy of right oxygenation avoiding non-invasive mechanical ventilation was life-saving. Seven-day mortality in SARS-CoV-2 requiring intubation was lower than 15%, with 80% of patients still requiring mechanical ventilation. After 15 days of ICU admission, half of patients remained intubated, whereas one third died.

Interactions between mephedrone and alcohol in humans: Cardiovascular and subjective effects

Introduction

Mephedrone is a synthetic cathinone derivative included in the class of “New-Novel Psychoactive Substances”. Synthetic cathinones are marketed as “bath salts” or “plant food” and gained notable popularity for similar effects to 4-methylenedioxymethamphetamine (MDMA, ecstasy), or amphetamines. Mephedrone is commonly consumed simultaneously with alcohol.

Objectives and aims

The aim of the present study was to evaluate the interactions between mephedrone and ethanol in humans.

Methods

Twelve healthy male, recreational users of psychostimulants participated as outpatients in four experimental sessions. They received a single oral dose of mephedrone (200 mg) and alcohol (0.8 g/kg), mephedrone placebo and alcohol (0.8 g/kg), mephedrone (200 mg) and placebo alcohol, and both placebos. Design was double-blind, double-dummy, randomized, cross-over and controlled with placebo. Study variables included: vital signs (blood pressure, heart rate, temperature, and pupil diameter), subjective effects (visual analogue scales-VAS, ARCI-49 item short form, and VESSPA questionnaire).

Results

The combination produced an increase in the cardiovascular effects of mephedrone and induced more intense feeling of euphoria and well-being in comparison to mephedrone and alcohol. Mephedrone reduced the drunkenness and sedation produced by alcohol.

Conclusions

These results are similar to those obtained with the combination of other psychostimulants as amphetamines and MDMA. Abuse liability of the combination is greater that induced by mephedrone.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

NGAL and SMAD1 gene expression in the early detection of diabetic nephropathy by liquid biopsy

INTRODUCTION

Diabetic nephropathy (DN) is a disease that progresses with the slow and progressive decline of the glomerular filtration rate (GFR); the installation of this pathology is silent and one of the major causes of death in patients with diabetes.

AIMS

To identify new molecular biomarkers for early identification of the onset of DN in patients with type II diabetes mellitus (DM2). We studied the expression profile of the genes; suppressor of mothers against decapentaplegic type 1 (SMAD1), neutrophil gelatinase-associated lipocalin (NGAL) and type IV collagen (COLIV1A) in peripheral blood and urine sediment samples.

METHODS

Ninety volunteers, 51 with DM2 and 39 healthy, were recruited from the Faculdade de Medicina do ABC outpatient clinic. We conducted an interview and collected anthropometric data, as well as blood and urine samples for biochemical evaluation and real-time PCR amplification of the genes of interest.

RESULTS

Gene expression data: peripheral blood NGAL (DM2 0.09758±0.1914 vs CTL 0.02293±0.04578), SMAD1 (blood: DM2 0.01102±0.04059* vs CTL 0.0001317±0.0003609; urine: DM2 0.7195±2.344* vs CTL 0.09812±0.4755), there was no significant expression of COLIV1A. These genes demonstrated good sensitivity and specificity in the receiving operating characteristic curve evaluation.

CONCLUSION

Our data suggest the potential use of NGAL and SMAD1 gene expression in peripheral blood and urine samples as early biomarkers of DN.

Assessment of vitamin D and inflammatory markers profile in cardiac tissue on Parkinson disease animal model

BACKGROUND

Cardiovascular dysfunctions are common non-motor symptoms in patients with Parkinson's disease (PD) that can result in reduced quality of life and even death. Research in animal models designed to characterize the pathological association between PD and cardiovascular abnormalities is still in its infancy. This study assessed the early impact of the nigrostriatal dopaminergic damage on cardiological features in the unilateral 6-OHDA rat model of PD.

METHODS

Male Wistar rats received unilateral intrastriatal injections of 6-OHDA and sham rats were injected with saline. Animals were studied 15 days later. Immunohistochemistry was used for visualization of tyrosine hydroxylase (TH)-positive neurons in the nigrostriatal system. Electrocardiogram recordings of heart rate were performed in conscious rats. Heart levels of vitamin D, inflammatory cytokines and C-reactive protein were assessed through electrochemiluminescence immunoassay, quantitative reverse transcription PCR and turbidimetric method, respectively.

RESULTS

We found a post-injury reduction of TH-immunoreactivity of approximately 45% in the substantia nigra pars compacta and 20% in the striatum. Heart rate reduction was found in 6-OHDA-lesioned rats as compared with sham counterparts. Reduced levels of vitamin D and increased levels of inflammatory factors (C-reactive protein, IL-6, TNF-α and TGF-β) were detected in the heart tissue of PD rats in comparison with sham.

CONCLUSION

Our findings suggest a link between cardiac tissue changes and cardiac functional changes early after the central dopaminergic damage induced by 6-OHDA. Knowledge of the cardiac abnormalities in the 6-OHDA model is critical in identifying future therapeutic targets and disease-modifying approaches for PD non-motor features.

Decreasing motion sickness by mixing different techniques

We investigated the effectiveness of galvanic cutaneous stimulation (GCS) and auditory stimulation (AS) together and separately in mitigating motion sickness (MS). Forty-eight drivers (twenty-two men; mean age = 21.58 years) participated in a driving simulation experiment. We compared the total scores of the Simulator Sickness Questionnaire (SSQ) across four different stimulation conditions (GCS, AS, Mixed GCS-AS and no stimulation as a baseline condition). We provided evidence that mixing techniques mitigates MS owing to an improvement in body balance; furthermore, mixing techniques improves driving behavior more effectively than GCS and AS in isolation. We encourage the use of the two techniques together to decrease MS.

Deep segmentation leverages geometric pose estimation in computer-aided total knee arthroplasty

Knee arthritis is a common joint disease that usually requires a total knee arthroplasty. There are multiple surgical variables that have a direct impact on the correct positioning of the implants, and an optimal combination of all these variables is the most challenging aspect of the procedure. Usually, preoperative planning using a computed tomography scan or magnetic resonance imaging helps the surgeon in deciding the most suitable resections to be made. This work is a proof of concept for a navigation system that supports the surgeon in following a preoperative plan. Existing solutions require costly sensors and special markers, fixed to the bones using additional incisions, which can interfere with the normal surgical flow. In contrast, the authors propose a computer-aided system that uses consumer RGB and depth cameras and do not require additional markers or tools to be tracked. They combine a deep learning approach for segmenting the bone surface with a recent registration algorithm for computing the pose of the navigation sensor with respect to the preoperative 3D model. Experimental validation using ex-vivo data shows that the method enables contactless pose estimation of the navigation sensor with the preoperative model, providing valuable information for guiding the surgeon during the medical procedure.

Expression of MMR system genes is correlated to NF-kB in patients with oral squamous cell carcinoma

AIMS

The aim of this study was to evaluate the mismatch repair gene expression and their correlation with NF-kB in patients with oral squamous cell carcinoma (SCC).

METHODS

Total RNA was isolated from 28 biopsy samples. A control group was composed of 20 volunteers. Differential expression of hMSH2, hMSH6 and NF-kB genes was accessed by quantitative PCR.

RESULTS

There is increased expression of all the analysed genes when the patients were smokers and alcoholics. In addition, there is increased expression of hMSH2 when SCC was removed from the base of the tongue. There was a correlation between NF-kB and hMSH2 and hMSH6 as well as between repair genes hMSH2 and hMSH6 expression levels. There is increased expression of the hMSH2 gene in patients with SCC, especially in the alcoholics.

CONCLUSIONS

There is a strong indication that NF-kB gene was expressed along with the studied repair genes, evidencing the possibility that this system can be activated by the inflammatory pathway.

Video-based computer navigation in knee arthroscopy for patient-specific ACL reconstruction

PURPOSE

The anterior cruciate ligament tear is a common medical condition that is treated using arthroscopy by pulling a tissue graft through a tunnel opened with a drill. The correct anatomical position and orientation of this tunnel are crucial for knee stability, and drilling an adequate bone tunnel is the most technically challenging part of the procedure. This paper presents the first guidance system based solely on intra-operative video for guiding the drilling of the tunnel.

METHODS

Our solution uses small, easily recognizable visual markers that are attached to the bone and tools for estimating their relative pose. A recent registration algorithm is employed for aligning a pre-operative image of the patient's anatomy with a set of contours reconstructed by touching the bone surface with an instrumented tool.

RESULTS

Experimental validation using ex-vivo data shows that the method enables the accurate registration of the pre-operative model with the bone, providing useful information for guiding the surgeon during the medical procedure. Experiments also demonstrate that the guided drilling of the tunnel leads to errors as low as 2.5 mm in the footprint and [Formula: see text] in orientation, which compares favourably to other works in the field.

CONCLUSION

The high accuracy and short time overhead evinced by the experimental validation combined with no additional incisions or capital equipment make this video-based computer-aided arthroscopy solution an appealing alternative to the existing approaches.

Influence of culture conditions on the technological properties of Carnobacterium maltaromaticum CNCM I-3298 starters

AIM

The aim of this study is to investigate the effect of a broad spectrum of culture conditions on the acidification activity and viability of Carnobacterium maltaromaticum CNCM I-3298, the main technological properties that determine the shelf-life of biological time-temperature integrator (TTI) labels.

METHODS AND RESULTS

Cells were cultivated at different temperatures (20-37°C) and pH (6-9·5) according to a modified central composite design and harvested at increasing times up to 10 h of stationary phase. Acidification activity and viability of freeze-thawed concentrates were assessed in medium mimicking the biological label. Acidification activity was influenced by all three culture conditions, but pH and harvest time were the most influential. Viability was not significantly affected by the tested range of culture conditions.

CONCLUSIONS

Carnobacterium maltaromaticum CNCM I-3298 must be cultivated at 20°C, pH 6 and harvested at the beginning of stationary phase to exhibit fastest acidification activities. However, if slower acidification activities are pursued, the recommended culture conditions are 30°C, pH 9·5 and a harvest time between 4-6 h of stationary phase.

SIGNIFICANCE AND IMPACT OF THE STUDY

Quantifying the impact of fermentation temperature, pH and harvest time has led to a predictive model for the production of biological TTI covering a broad range of shelf-lives.

High frequency of CHD7 mutations in congenital hypogonadotropic hypogonadism

Congenital hypogonadotropic hypogonadism (CHH) is characterized by lack of normal pubertal development due to deficient gonadotropin-releasing hormone (GnRH) secretion or action, and is caused by genetic defects in several genes. Mutations in the CHD7 gene cause CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and development, Genital hypoplasia and Ear abnormalities), but have also been found in patients with isolated CHH. The aim of this study was to identify CHD7 mutations in patients with CHH. Fifty Portuguese patients with CHH were screened for mutations in the CHD7 gene by DNA sequencing. Eight (16%) patients had CHD7 rare sequence variants that consisted of six missense (p.Gly388Glu, p.His903Pro, p.Thr1082Ile, p.Val1452Leu, p.Asp1854Gly, and p.Arg2065His) and two synonymous (p.Ser559Ser, and p.Ala2785Ala) mutations. Five of these mutations have never been reported before. Three CHD7 mutations occurred in patients that had mutations in additional CHH-genes. This study uncovered novel genetic variants that expand the known spectrum of mutations associated with CHH. The frequency of CHD7 mutations in this cohort was higher than that of other major CHH-genes and confirms the importance of including CHD7 in the genetic testing of CHH, even in the absence of additional CHARGE features.

Introducing curcumin biosynthesis in Arabidopsis enhances lignocellulosic biomass processing

Lignin is the main cause of lignocellulosic biomass recalcitrance to industrial enzymatic hydrolysis. By partially replacing the traditional lignin monomers by alternative ones, lignin extractability can be enhanced. To design a lignin that is easier to degrade under alkaline conditions, curcumin (diferuloylmethane) was produced in the model plant Arabidopsis thaliana via simultaneous expression of the turmeric (Curcuma longa) genes DIKETIDE-CoA SYNTHASE (DCS) and CURCUMIN SYNTHASE 2 (CURS2). The transgenic plants produced a plethora of curcumin- and phenylpentanoid-derived compounds with no negative impact on growth. Catalytic hydrogenolysis gave evidence that both curcumin and phenylpentanoids were incorporated into the lignifying cell wall, thereby significantly increasing saccharification efficiency after alkaline pretreatment of the transgenic lines by 14-24% as compared with the wild type. These results demonstrate that non-native monomers can be synthesized and incorporated into the lignin polymer in plants to enhance their biomass processing efficiency.

Biomechanical analysis of metacarpophalangeal joint arthroplasty with metal-polyethylene implant: An in-vitro study

BACKGROUND

The most common implant options for the metacarpophalangeal joint arthroplasty include silicone, pyrocarbon and metal-polyethylene. A systematic review of outcomes of silicone and pyrocarbon implants was conducted; however, a similar exercise for metal-polyethylene implants revealed a scarcity of published results and lack of long-term follow-up studies. The aim of the present work is to test the hypothesis that the magnitude of metacarpophalangeal joint cyclic loads generates stress and strain behaviour, which leads to long-term reduced risk of metal-polyethylene component loosening.

METHODS

This study was performed using synthetic metacarpals and proximal phalanges to experimentally predict the cortex strain behaviour for both intact and implanted states. Finite element models were developed to assess the structural behaviour of cancellous-bone and metal-polyethylene components; these models were validated by comparing cortex strains predictions against the measurements.

FINDINGS

Cortex strains in the implanted metacarpophalangeal joint presented a significant reduction in relation to the intact joint; the exception was the dorsal side of the phalanx, which presents a significant strain increase. Cancellous-bone at proximal dorsal region of phalanx reveals a three to fourfold strain increase as compared to the intact condition. Interpretation The use of metal-polyethylene implant changes the strain behaviour of the metacarpophalangeal joint yielding the risk of cancellous-bone fatigue failure due to overload in proximal phalanx; this risk is more important than the risk of bone-resorption due to the strain-shielding effect. By limiting the loads magnitude over the joint after arthroplasty, it may contribute to the prevention of implant loosening.

Osteochondral allograft in a patient with avascular necrosis of the knee secondary to lupus

Joint preservation surgery is accepted in cases of secondary osteonecrosis of the knee without joint collapse. However, there is no consensus on the best treatment: debridement and drilling, or use of auto- or allograft. The author describes a clinical case with 15 years of evolution where allogeneic osteochondral graft was used in the treatment of osteonecrosis of the lateral femoral condyle in a young woman with systemic lupus. In spite of having other options and of the results reported in the literature, the functional evaluation 15 years later presented excellent results, with total autonomy of the patient for daily life and work tasks, indicating that the option for osteochondral allograft may be a good solution.

Allograft of the knee extensor in cases of patellar tendon rupture in total arthroplasty patients

Objective

Retrospective study to evaluate the functional results of patients with total knee arthroplasty and rupture of the patellar tendon, submitted to transplantation of the extensor knee apparatus with fresh frozen allograft.

Method

Nine patients, operated between 2003 and 2015, with a minimum of one year of follow-up. All patients were reviewed by performing a functional evaluation using the Knee Society score. Preoperative values were compared with those of the final evaluation.

Results

Mean survival was 2.7 ± 1.9 years (14–1). The knee score improved from 38 ± 4.5 to 70 ± 8.5, and functional score from 30 ± 6.5 to 90 ± 3.5. Mean extension deficit was 5 (1–15). Mean range of motion was 80 (60–100).

Conclusion

The use of allograft is a solution for extreme cases of patellar rupture after total knee arthroplasty, providing reasonable functional results and representing an alternative to knee arthrodesis.

Charcot osteoarthropathy of the knee secondary to neurosyphilis: a rare condition managed by a challenging arthrodesis

The Charcot joint or neuropathic osteoarthropathy was first described as an arthritic sequela of neurosyphilis (tabes dorsalis). It results in significant joint destruction and instability. Nowadays, it is a very rare condition and represents a considerable challenge to the orthopaedic surgeon. The authors describe the case of a patient diagnosed with neurosyphilis who was requested an orthopaedic consultation for an enlarged and unstable knee. The diagnosis of Charcot knee was made and based on the clinical and radiographical findings combined with the patient's medical history. Knee arthrodesis was the surgical treatment chosen to preserve the limb and only succeeded at second attempt. At 4 years of follow-up, it proved to be an effective surgical treatment. In this article, we focus on the importance of early recognition of joint changes in these patients in order to prevent irreversible joint loss.

Gitelman syndrome and primary hyperparathyroidism: a rare association

Gitelman syndrome(GS) is a rare autosomal recessive salt-losing tubulopathy of young adults, characterised by hypokalaemia, hypomagnesaemia, hypocalciuria and secondary hyperaldosteronism. Hypercalcaemia due to hypocalciuria in these patients is extremely rare.A 25-year-old healthy woman was referred to the Endocrinology clinic for evaluation of persistent hypokalaemia. She presented with fatigue, myalgias, cramps and paraesthesia. Her physical examination was normal. Laboratory workup revealed: K⁺ 2.7 mEq/L (r.v.3.5-5.1), 24 hours urinary K⁺ 84.7 mEq/24 hours (r.v.25-125), Mg²⁺ 0.71 mg/dL (r.v.1.6-2.6), 24 hours urinary Mg²⁺ 143.1 mg/24 hours (r.v.73-122), Ca²⁺ 12 mg/dL (r.v.8.4-10.2), aldosterone 47.1 ng/mL (r.v. 4-31) and active renin 374.7 uUI/mL (r.v.4.4-46.1). She was diagnosed with GS and was treated with spironolactone, oral K⁺ and Mg²⁺ supplementation. Further investigation confirmed hypercalcaemia due to primary hyperparathyroidism owing to a single parathyroid adenoma. Following parathyroidectomy serum calcium normalised.Current knowledge favours that hypomagnesaemia in patients with GS protects them from hypercalcaemia. In this context of multiple electrolyte imbalances, correction of hypomagnesaemia is a challenge and should be done carefully. Like in our patient, aetiology of hypercalcaemia should be promptly diagnosed and reversed.

Cytokeratin 19 Expression by Reverse Transcriptase-Polymerase Chain Reaction in the Peripheral Blood of Prostate Cancer Patients

Aims and background

Sensitive reverse transcriptase-polymerase chain reaction-based techniques for detection of epithelial antigen expression, such as cytokeratin 19, in the peripheral blood mononuclear fraction of prostate cancer patients may allow the detection of tumor progression at A molecular level.

Methods

We studied cytokeratin 19 expression by reverse transcriptase-polymerase chain reaction in peripheral blood mononuclear cell samples of 10 control men and serially in 44 patients with prostate cancer every three months for 18 months.

Results

None of the 10 normal control men expressed cytokeratin 19 in their peripheral blood mononuclear fraction. In the patients, cytokeratin 19 positivity at entry was not associated with age, Gleason score, clinical stage, prostate-specific antigen or alkaline phosphatase. Interestingly, having at least one positive cytokeratin 19 result during follow-up correlated significantly with time to prostate-specific antigen progression (P = 0.049), especially in the subgroup of metastatic patients (P = 0.032).

Conclusions

We conclude that cytokeratin 19 expression by reverse transcriptase-polymerase chain reaction in the peripheral blood mononuclear cell fraction of prostate cancer patients correlates with time to prostate-specific antigen progression. Further studies are needed to confirm these findings.

Expanding the genetic spectrum of ANOS1 mutations in patients with congenital hypogonadotropic hypogonadism

STUDY QUESTION

What is the prevalence and functional consequence of ANOS1 (KAL1) mutations in a group of men with congenital hypogonadotropic hypogonadism (CHH)?

SUMMARY ANSWER

Three of forty-two (7.1%) patients presented ANOS1 mutations, including a novel splice site mutation leading to exon skipping and a novel contiguous gene deletion associated with ichthyosis.

WHAT IS KNOWN ALREADY

CHH is characterized by lack of pubertal development and infertility, due to deficient production, secretion or action of GnRH, and can be associated with anosmia/hyposmia (Kallmann syndrome, KS) or with a normal sense of smell (normosmic CHH). Mutations in the anosmin-1 (ANOS1) gene are responsible for the X-linked recessive form of KS.

STUDY DESIGN, SIZE, DURATION

This cross-sectional study included 42 unrelated men with CHH (20 with KS and 22 with normosmic CHH).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were screened for mutations in the ANOS1 gene by DNA sequencing. Identified mutations were further investigated by RT-PCR analysis and multiplex ligation-dependent probe amplification (MLPA) analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Hemizygous mutations were identified in three (7.1%) KS cases: a novel splice acceptor site mutation (c.542-1G>C), leading to skipping of exon 5 in the ANOS1 transcript in a patient with self-reported normosmia (but hyposmic upon testing); a recurrent nonsense mutation (c.571C>T, p.Arg191*); and a novel 4.8 Mb deletion involving ANOS1 and eight other genes (VCX3B, VCX2, PNPLA4, VCX, STS, HDHD1, VCX3A and NLGN4X) in KS associated with ichthyosis.

LIMITATIONS, REASONS FOR CAUTION

Objective olfactory testing was not performed in all cases of self-reported normosmia and this may have underestimated the olfactory deficits.

WIDER IMPLICATIONS OF THE FINDINGS

This study further expands the spectrum of known genetic defects associated with CHH and suggests that patients with self-reported normal olfactory function should not be excluded from ANOS1 genetic testing.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Portuguese Foundation for Science and Technology. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Biomechanical evaluation of pyrocarbon proximal interphalangeal joint arthroplasty: An in-vitro analysis

BACKGROUND

Pyrocarbon proximal interphalangeal joint arthroplasty provided patients with excellent pain relief and joint motion, however, overall implant complications have been very variable, with some good outcomes at short-medium-term follow-up and some bad outcomes at longer-term follow-up. Implant loosening with migration, dislocation and implant fracture were the main reported clinical complications. The aim of the present work was to test the hypothesis that the magnitude proximal interphalangeal joint cyclic loads in daily hand functions generates stress-strain behaviour which may be associated with a risk of pyrocarbon component loosening in the long-term.

METHODS

This study was performed using synthetic proximal and middle phalanges to experimentally predict the cortex strain behaviour and implant stability considering different load conditions for both intact and implanted states. Finite element models were developed to assess the structural behaviour of cancellous-bone and pyrocarbon components, these models were validated against experimentally measured cortex strains.

FINDINGS

Cortex strains showed a significant increase at dorsal side and reduction at palmar side between intact and implanted states. Cancellous-bone adjacent to the condylar implant base components suffers a two to threefold strain increase, comparing with the intact condition.

INTERPRETATION

The use of pyrocarbon implant changes the biomechanical behaviour of the joint phalanges and is associated with a potential risk of support cancellous-bone suffer fatigue failure in mid to long term due to the strain increase for cyclic loads in the range of daily hand activities, this risk is more prominent than the risk of bone resorption due to strain-shielding effect.