Understanding immune-mediated cobalt/chromium allergy to orthopaedic implants: a meta-synthetic review

BACKGROUND

The frequency of primary joint replacement surgery continues to increase worldwide. While largely considered biologically inert entities, an increasing body of evidence continues to validate a not insignificant incidence of allergic reactions to such implants. Little previous work has explored genuinely immune-mediated reactivity in this context. In the absence of a contemporary published summary on the topic, this paper explored the current state of understanding of cobalt/chromium allergy and proposes a patient management algorithm whereby such immune reactions are clinically suggested.

METHODS

A structured, systematic literature review was performed by following PRISMA search principles to provide an updated review of this area.

RESULTS

Thirty-six topic-related articles were identified, the majority reflecting lower tiers of scientific evidence with a lack of homogeneous quantitative data to facilitate valid cohort comparisons. Largely, the available literature represented small case series' or expert opinions.

CONCLUSIONS

Despite increasing clinical awareness and acknowledgement of true allergy to joint replacement components, this review highlighted that the evidence base underpinning the diagnosis and management of such patients is limited. Both patient-reported metal allergy or skin patch testing are grossly unreliable methods and show almost no correlation with true immune reactivity. Recent studies suggested a potential role for patient-specific in vitro cellular activation testing and/or targeted genetic testing when cobalt/chromium allergy is clinically suspected. However, while likely representing the contemporary "best available" approaches both can be costly undertakings, are not yet universally available, and still require broader validation in non-research settings before wider uptake can be championed.

The Diagnostic Utility of Serum Metal Ion Markers for High-Grade Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesions (ALVALs) in Revision Hip and Knee Arthroplasty: An International Multicenter Study

BACKGROUND

Aseptic lymphocyte-dominated vasculitis-associated lesions (ALVALs) are typically described in the context of metal-on-metal (MoM) hip bearings. This study explores the diagnostic utility of preoperative serum cobalt and chromium ion levels in determining the histological grade of ALVAL in revision hip and knee arthroplasty.

METHODS

This was a multicenter retrospective review of 26 hips and 13 knees assessing the correlation between preoperative ion levels (mg/L (ppb)) and the histological grade of ALVAL from intraoperative specimens. The diagnostic ability of preoperative serum cobalt and chromium levels to determine high-grade ALVAL was assessed using a receiver operating characteristic (ROC) curve.

RESULTS

In the knee cohort, there was a higher serum cobalt level in high-grade ALVAL cases (10.2 mg/L (ppb) versus 3.1 mg/L (ppb)) (P = .0002). The Area Under the Curve (AUC) was 1.00 (95% confidence interval (CI) 1.00 to 1.00). There was a higher serum chromium level in high-grade ALVAL cases (12.25 mg/L (ppb) versus 7.77 mg/L (ppb)) (P = .0002). The AUC was 0.806 (95% CI 0.555 to 1.00). In the hip cohort, there was a higher serum cobalt level in high-grade ALVAL cases (333.5 mg/L (ppb) versus 119.9 mg/L (ppb)) (P = .0831). The AUC was 0.619 (95% CI 0.388 to 0.849). There was a higher serum chromium level in high-grade ALVAL cases (186.4 mg/L (ppb) versus 79.3 mg/L (ppb)) (P = .183). The AUC was 0.595 (95% CI 0.365 to 0.824).

CONCLUSIONS

Histologically, high-grade ALVAL has significantly higher preoperative serum cobalt and chromium ion levels in revision TKA. Preoperative serum ion levels have excellent diagnostic utility in revision TKA. Cobalt levels in revision THA have a fair diagnostic ability and chromium levels had a poor diagnostic ability.

Corrigendum to "Early Revision Rates of Total Hip Arthroplasty Using the Intellijoint HIP Computer Navigation System: A Study From the Australian National Joint Replacement Registry of 1911 Procedures." [Arthroplasty Today 18 (2022) 149-156]

[This corrects the article DOI: 10.1016/j.artd.2022.09.019.].

Quantifying anterior pelvic roll during total hip arthroplasty in the lateral decubitus position

BACKGROUND

Unintended pelvic positional change is an acknowledged intra-operative problem for hip arthroplasty, seen commonly with procedures performed in the lateral position. If unrecognised, such changes can dramatically alter final acetabular component anteversion potentially resulting in suboptimal construct performance. It has previously been suggested that pelvic roll of just 13° may be enough to place an otherwise perfectly orientated cup outside of conventional ± 10° safe zones. Using the real-time tracking capacity of a commercially available optical navigation system, we aimed to accurately quantify pelvic roll occurring during total hip arthroplasties (THAs) performed in the decubitus position.

METHODS

Prospectively collected data for 107 consecutive, unilateral, THAs were interrogated to determine the magnitude of pelvic movement around a central longitudinal axis (i.e. AP roll). Correlation statistics with patient age and body mass index (BMI) were also calculated.

RESULTS

A mean pelvic roll of 9.5° was observed, being anterior in 96% of cases. Of these, 18.3% of hips had a magnitude of roll greater than 13°. There were no statistically significant independent correlations observed between age (p = 0.87) or BMI (p = 0.59) and mean roll.

CONCLUSIONS

Errors in achieving acetabular target version may result in numerous post-operative concerns including instability/dislocation, bearing wear, squeaking, range-of-movement limitation and increased revision rate. In a general cohort, our findings suggest a mean anterior pelvic roll during THA of nearly 10°. Without purposeful correction, this may cause substantial deviation from intended target positions. Future work is indicated to map changing pelvic roll during THA which is likely to follow a nonlinear trajectory. Level of evidence: IV. .

A role for artificial intelligence applications inside and outside of the operating theatre: a review of contemporary use associated with total knee arthroplasty

BACKGROUND

Artificial intelligence (AI) has become involved in many aspects of everyday life, from voice-activated virtual assistants built into smartphones to global online search engines. Similarly, many areas of modern medicine have found ways to incorporate such technologies into mainstream practice. Despite the enthusiasm, robust evidence to support the utility of AI in contemporary total knee arthroplasty (TKA) remains limited. The purpose of this review was to provide an up-to-date summary of the use of AI in TKA and to explore its current and future value.

METHODS

Initially, a structured systematic review of the literature was carried out, following PRISMA search principles, with the aim of summarising the understanding of the field and identifying clinical and knowledge gaps.

RESULTS

A limited body of published work exists in this area. Much of the available literature is of poor methodological quality and many published studies could be best described as "demonstration of concepts" rather than "proof of concepts". There exists almost no independent validation of reported findings away from designer/host sites, and the extrapolation of key results to general orthopaedic sites is limited.

CONCLUSION

While AI has certainly shown value in a small number of specific TKA-associated applications, the majority to date have focused on risk, cost and outcome prediction, rather than surgical care, per se. Extensive future work is needed to demonstrate external validity and reliability in non-designer settings. Well-performed studies are warranted to ensure that the scientific evidence base supporting the use of AI in knee arthroplasty matches the global hype.

Identification of protective and 'at risk' HLA genotypes for the development of pseudotumours around metal-on-metal hip resurfacings

Hip resurfacing remains a potentially valuable surgical procedure for appropriately-selected patients with optimised implant choices. However, concern regarding high early failure rates continues to undermine confidence in use. A large contributor to failure is adverse local tissue reactions around metal-on-metal (MoM) bearing surfaces. Such phenomena have been well-explored around MoM total hip arthroplasties, but comparable data in equivalent hip resurfacing procedures is lacking. In order to define genetic predisposition, we performed a case-control study investigating the role of human leucocyte antigen (HLA) genotype in the development of pseudotumours around MoM hip resurfacings. A matched case-control study was performed using the prospectively-collected database at the host institution. In all, 16 MoM hip resurfacing 'cases' were identified as having symptomatic periprosthetic pseudotumours on preoperative metal artefact reduction sequence (MARS) MRI, and were subsequently histologically confirmed as high-grade aseptic lymphocyte-dominated vasculitis-associated lesions (ALVALs) at revision surgery. 'Controls' were matched by implant type in the absence of evidence of pseudotumour. Blood samples from all cases and controls were collected prospectively for high resolution genetic a nalysis targeting 11 separate HLA loci. Statistical significance was set at 0.10 a priori to determine the association between HLA genotype and pseudotumour formation, given the small sample size. Using a previously-reported ALVAL classification, the majority of pseudotumour-positive caseswere found to have intermediate-grade group 2 (n = 10; 63%) or group 3 (n = 4; 25%) histological findings. Two further patients (13%) had high-grade group 4 lesions. HLA-DQB1*05:03:01 (p = 0.0676) and HLA-DRB1*14:54:01 (p = 0.0676) alleles were significantly associated with a higher risk of pseudotumour formation, while HLA-DQA1*03:01:01 (p = 0.0240), HLA-DRB1*04:04:01 (p = 0.0453), HLA-C*01:02:01 (p = 0.0453), and HLA-B*27:05:02 (p = 0.0855) were noted to confer risk reduction. These findings confirm the association between specific HLA genotypes and the risk of pseudotumour development around MoM hip resurfacings. Specifically, the two 'at risk' alleles (DQB1*05:03:01 and DRB1*14:54:01) may hold clinical value in preoperative screening and prospective surgical decision-making.

Early Revision Rates of Total Hip Arthroplasty Using the Intellijoint HIP Computer Navigation System: A Study From the Australian National Joint Replacement Registry of 1911 Procedures

Background

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis. The aim of this study was to determine the revision outcome of commercially available navigation technologies.

Methods

Data from the Australian Orthopaedic Association National Joint Replacement Registry from January 2016 to December 2020 included all primary THA procedures performed for osteoarthritis. Procedures using the Intellijoint HIP navigation system were identified and compared to procedures using "other" computer navigation systems and to nonnavigated procedures. The cumulative percent revision (CPR) was compared between the 3 groups using Kaplan-Meier estimates of survivorship and hazard ratios from Cox proportional hazards models, adjusted for age and gender.

Results

There were 1911 procedures that used the Intellijoint system, 4081 used "other" computer navigation systems, and 160,661 were nonnavigated procedures. The all-cause 2-year CPR rate for the Intellijoint system was 1.8% (95% confidence interval [CI], 1.2-2.6), compared to 2.2% (95% CI, 1.8-2.8) for other navigated cases and 2.2% (95% CI, 2.1-2.3) for nonnavigated cases. A prosthesis analysis identified the Paragon/Acetabular Shell THAs combined with the Intellijoint system to have a higher (3.4%) rate of revision than nonnavigated THAs (hazard ratio = 2.00 [95% CI, 1.01-4.00], P = .048). When this combination was excluded, the Intellijoint group demonstrated a 2-year CPR of 1.3%. There was no statistical difference in the CPR between the 3 groups before or after excluding the Paragon/Acetabular Shell system.

Conclusions

The preliminary data presented demonstrate no statistical difference in all-cause revision rates when comparing the Intellijoint system with "other" navigation systems and "nonnavigated" approaches for primary THAs.

Level of evidence

III (National registry analysis).

Clinical Impact of Pelvic Malrotation on Radiograph-Based Preoperative Planning for Total Hip Arthroplasty: A Proof-of-Concept and Prudent Prediction of Acceptable Rotation

Introduction

Pelvic rotation (PR) on preoperative radiograph templating can affect various critical measured acetabular angles and potentially outcomes of successful total hip arthroplasty (THA). Optimising anatomical reconstruction of the joint is essential to achieve function, longevity and prevention of complications following surgery. There is limited literature that standardises the degree of acceptable PR on radiograph or its effects on the fitting of acetabular prostheses.

Objective

This study aimed to develop a proof-of-concept that quantifies how PR can affect various acetabular angles used in pre-operative THA templating and to formulate a practicable method of determining if the preoperative PR is acceptable.

Materials and methods

Computerised tomography (CT) models from three control and two THA patients were generated and manipulated in various degrees of PR. CT slices were thickened to simulate radiographs and acetabular angles measured.

Results

The acetabular anteversion distance (AAD) and lateral opening angle (LOA) demonstrated a linear and quadratic relationship with good correlation (R 2 = 0.923, R 2 = 0.710 respectively, p < 0.0001) in relation to PR. Change in area of prosthesis (AOP) demonstrated a good linear correlation (r 2 = 0.774 and r 2 = 0.875, p < 0.0001) with PR. Two novel measurements were used to estimate the degree of PR from a pelvic radiograph; the horizontal distance between pubic symphysis and middle of sacrococcygeal joint (PSSC) and the simplified pelvic rotation ratio (SPRR). A strong correlation between PSSC and SPRR with change in PR was observed (R 2 = 0.970, R 2 = 0.953, p < 0.001).

Conclusion

Preliminary result suggests that an SPRR > 2.0 correlates to PR > 20° with potential to have a clinical impact on preoperative measurements.

Patellar button compatibility in the conversion of Patellofemoral Arthroplasty to a Total Knee Arthroplasty: A review of the contemporary literature

BACKGROUND

Compared to total knee arthroplasty (TKA), patellofemoral arthroplasty (PFA) is a far less commonly performed operation. However, in carefully selected cohorts, PFA continues to be an appropriate treatment option for end-stage isolated patellofemoral joint osteoarthritis. In the later situation whereby a PFA is considered for conversion to a TKA - often due to disease progression - uncertainty remains regarding optimal management of the in situ patellar button. This review of the contemporary literature aimed to provide a summary of the current evidence to support surgeon decision-making, by evaluating the compatibility, efficacy, and survivorship of retained versus revised patellar buttons in PFA-to-TKA conversion. Specific focus was paid to implant design and technical considerations during revision, plus post-operative patient-reported outcomes and modes of secondary patellar component failure.

METHODS

A review of the Embase, Cochrane and PubMed databases was performed following PRISMA search principles.

RESULTS

This investigation highlights that the fate of patellar buttons in PFA-to-TKA conversion has previously been poorly studied, with scant publication data available. Most reports have been of singular cases or small cohort series. Larger formal RCTs and level 1 evidence are lacking.

CONCLUSION

The findings herein suggest that surgeons can confidently retain well-fixed, undamaged, dome-shaped all-polyethylene patellar buttons in the conversion of a PFA to TKA with the expectation of acceptable mid-term performance and survivorship, as long as congruent tracking with the new tibiofemoral components is achieved. This result is likely translatable to the majority of contemporary, all-polyethylene, dome-shaped patellar buttons, even with manufacturer mismatch.

Artificial intelligence in orthopedic surgery: evolution, current state and future directions

Technological advances continue to evolve at a breath-taking pace. Computer-navigation, robot-assistance and three-dimensional digital planning have become commonplace in many parts of the world. With near exponential advances in computer processing capacity, and the advent, progressive understanding and refinement of software algorithms, medicine and orthopaedic surgery have begun to delve into artificial intelligence (AI) systems. While for some, such applications still seem in the realm of science fiction, these technologies are already in selective clinical use and are likely to soon see wider uptake. The purpose of this structured review was to provide an understandable summary to non-academic orthopaedic surgeons, exploring key definitions and basic development principles of AI technology as it currently stands. To ensure content validity and representativeness, a structured, systematic review was performed following the accepted PRISMA principles. The paper concludes with a forward-look into heralded and potential applications of AI technology in orthopedic surgery.While not intended to be a detailed technical description of the complex processing that underpins AI applications, this work will take a small step forward in demystifying some of the commonly-held misconceptions regarding AI and its potential benefits to patients and surgeons. With evidence-supported broader awareness, we aim to foster an open-mindedness among clinicians toward such technologies in the future.

Eradicating Fungal Periprosthetic TKA "Super-infection": Review of the Contemporary Literature and Consideration of Antibiotic-Impregnated Dissolving Calcium Sulfate Beads as a Novel PJI Treatment Adjunct

Fungal periprosthetic joint infections are an uncommon but potentially devastating complication of arthroplasty surgery. The concurrent presence of a coexistent bacterial pathogen—a so called “super-infection”—adds further complexity. With delays to definitive diagnosis and a large number of procedures before cure, the associated physical and psychological morbidity is considerable. Beyond this, the economic and resource burden can be substantial. This case report presents the successful rapid treatment of an atypical bacterial and fungal periprosthetic super-infection with two-stage revision surgery augmented with a commercially available dissolving calcium sulfate bead system permitting targeted local antifungal elution. While not the panacea for treatment, these beads provide another potentially useful tool in the atypical pathogen eradication armamentarium. Much research is still indicated to define the optimal care pathway for fungal periprosthetic super-infections.

Retained pelvic pin site debris after navigated total hip replacement: Masquerading as an early-stage chondrosarcomatous lesion

Once purely the domain of knee surgery, the use of computer-navigated techniques in total hip arthroplasty (THA) is becoming progressively more commonplace. As with the adoption of any new technology-assisted approach, the uptake of navigated THA utilization has heralded a new suite of technique-specific potential complications. One such example – not usually seen with conventional instrumented THA – pertains to complications related to the insertion and use of fixed pelvic array trackers. This case report describes the unusual circumstance of retained local bony debris generated through application of self-drilling, self-tapping iliac crest pins (for rigid navigation tracker placement) being mis-interpreted on advanced imaging - at a hospital site remote from the index surgery - as an aggressive, early-stage, chondrosarcomatous lesion. This case highlights the critical importance of both a general awareness of common imaging findings after navigated THA surgery (whereby tracker pins have been employed) and the value of 'hands on' clinical assessment of patients to allow correlation with suspicious imaging findings.

Pseudotumors and High-Grade Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesions Around Total Knee Replacements Identified at Aseptic Revision Surgery: Findings of a Large-Scale Histologic Review

BACKGROUND

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) development (including pseudotumors) secondary to metal debris generation around total hip arthroplasties is a well-recognized histopathologic phenomenon. Emerging data have highlighted a similar potential concern around TKAs although the body-of-knowledge has largely been limited to individual case reports or small retrospective case series. This study sought to establish the prevalence of pseudotumors or high-grade ALVALs seen at the revision of primary TKAs and to establish the correlation between histologic ALVAL grade and patient-reported functional outcome measures.

METHODS

The findings of 321 non-infective (aseptic) patients undergoing unilateral revision knee surgery, at a high-volume tertiary referral center, were reviewed. Each case was independently histologically classified. Complete patient-reported functional outcome measures were available for 134 patients (42%) allowing correlation between functional performance and histopathology results.

RESULTS

Five distinct pseudotumors and a further 18 high-grade ALVALs were histologically identified representing 1.6% and 5.6% of the cohort, respectively. When compared by histologic grade, Oxford Knee Score and Western Ontario and McMaster University's Osteoarthritis Index suggested a high correlation between ALVAL grade and functional knee scores.

CONCLUSION

These findings suggest a prevalence of pseudotumors or high-grade ALVALs at revision TKA surgery of >7%. This unexpectedly high result may contribute insight into the previously under-appreciated significance of metal debris-related local tissue reactions around TKAs. The findings also demonstrate a strong near-linear inverse relationship between patient-reported clinical knee performance and the underlying histologic grade of local tissue reaction. These results have potential management implications for patients with underperforming TKAs and should prompt consideration of an ALVAL secondary to metallosis in the differential diagnosis.

LEVEL OF EVIDENCE

This is a retrospective cohort study with Level III evidence.

Frank Stinchfield Award: Identification of the At-risk Genotype for Development of Pseudotumors Around Metal-on-metal THAs

BACKGROUND

Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive.

QUESTIONS/PURPOSES

The aim of this research, as a clinical-genotype correlation analysis, was to identify specific alleles (genes) associated with the development of ALTRs in patients with in situ MoM THAs.

METHODS

A case-control study of patients who received a large-head, primary MoM THA between 2005 and 2008 was performed with a minimum followup of 5 years. Twenty-six patients who had undergone revision of a primary MoM THA secondary to symptomatic ALTRs were recruited. The mean timeframe from primary MoM THA to symptomatic revision was 5.5 years (range, 1-10 years). Twenty-eight control subjects were randomly selected asymptomatic patients with no evidence of ALTRs on protocol-specific screening. Baseline demographics and high-resolution genotype (human leukocyte antigen [HLA] Class II) were collected for all patients. Cohorts were similar with respect to age at the time of primary MoM THA (mean, 54.8 versus 54.9 years, p = 0.95) and serum cobalt (mean, 5.5 versus 8.5 μg/L, p = 0.09) and chromium concentrations (mean, 2.9 versus 4.2 μg/L, p = 0.27). The association between genotype and revision surgery secondary to ALTRs was determined with gender as a covariate.

RESULTS

The prevalence of the risk genotype was 30% (16 of 54) among the entire cohort. Adjusting for sex, the odds of revision were 6.1 times greater among patients with the risk genotype present than among patients without (95% confidence interval [CI], 1.5-25.4; p = 0.01). Among females, the specificity of the risk genotype was 1.0 (95% CIexact, 0.5-1.0; pexact = 0.03), and for males, it was 0.8 (95% CIexact, 0.6-0.9; pexact < 0.01).

CONCLUSIONS

The findings of this study suggest that, among patients with a primary MoM THA, allelic variation within the HLA Class II loci may be a strong, independent risk factor associated with the need for subsequent revision surgery secondary to pseudotumor formation.

CLINICAL RELEVANCE

Given the hypothesis-generating nature of this novel undertaking, confirmatory prospective clinical studies are required to further elucidate this correlation and to explore the clinical utility of targeted genetic screening in this specific population. This research may, however, represent a key missing piece in the puzzle that is metal ion-induced pseudotumor formation.

Simplifying the upper limb peripheral motor screen: Proposing the "K" sign

The well-recognized erosion of pathoanatomic correlations in basic medical training, combined with the increasing everyday pressures of time-efficacy in patient examination, continue to place strain on junior clinicians. Over the years, many refinements to tried-and-true basic physical examination techniques have been described, allowing improvement in diagnostic yield. A multitude of “screening” techniques are available for physical assessment; however, such approaches are often nonstandardized and inconsistently taught and applied in the clinical realm. Great interexaminer inconsistency in the documentation of many forms of screening techniques also substantively undermines their respective clinical value. The current work presents a novel refinement/combination of previously described examination approaches for the assessment of peripheral upper limb (UL) motor function — the “K” sign. Having been successfully applied in both the acute and ambulatory clinical settings for several years, we feel that the technique has a useful role as a rapid and specific screening technique that is easily taught, learnt, and applied. Arguably, its employment serves to improve time efficacy in the screening examination, and may even improve diagnostic yield through its reliable reproducibility and provision of direct bilateral comparison. Its inherent simplicity also lends itself well to high levels of uptake (and retention) by medical students and junior clinicians alike. On top of presenting the simple screening test itself, we offer a simple means of subsequent notation for the patient's case note record, again in the hope of standardization and endurance of clinical value beyond the time of patient examination.

The effect of nonsteroidal anti-inflammatory drug administration on acute phase fracture-healing: a review

BACKGROUND

The analgesic efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) is well established, and these agents often form an integral part of posttraumatic pain management. However, potentially deleterious effects of resulting prostaglandin suppression on fracture-healing have been suggested.

METHODS

A systematic literature review involving searches of electronic databases and online sources was performed to identify articles exploring the influence of NSAIDs on fracture-healing.

RESULTS

A structured search approach identified 316 papers as potentially relevant to the topic, and these were manually reviewed. The majority described small-scale studies that were retrospective or observational in nature, with limited control of potentially confounding variables, or presented little key information that was not also present in other studies.

CONCLUSIONS

Although increasing evidence from animal studies suggests that cyclooxygenase-2 (COX-2) inhibition suppresses early fracture-healing, in vivo studies involving human subjects have not provided convincing evidence to substantiate this concern. We found no robust evidence to attest to a significant and appreciable patient detriment resulting from the short-term use of NSAIDs following a fracture. The balance of evidence in the available literature appears to suggest that a short-duration NSAID regimen is a safe and effective supplement to other modes of post-fracture pain control, without a significantly increased risk of sequelae related to disrupted healing.

Review article: thromboprophylaxis after total hip replacement

The risk of secondary haematologic complications such as deep vein thrombosis or pulmonary embolism increases significantly when a transient period of hypercoagulability is induced after total hip replacement (THR). A number of drug-based anticoagulant approaches are available to modulate this risk, but the optimal length of therapy for such approaches remains unclear. The literature was reviewed for evidence-based support of the routine use of an extended course (>14 days) of thromboprophylaxis after THR. Electronic databases and real-time online literature searches were performed, using the PubMed (Medline), EMBASE, CINAHL and GoogleScholar, and the Cochrane and British Medical Journal Clinical Evidence libraries. Author-defined key word searches were performed. Only articles in the English language, for which full text could be retrieved, were reviewed. There is robust evidence to support an extended course (>14 days) of thromboprophylaxis after THR. Such recommendations have been translated into the guidelines of key professional bodies, including those of the American College of Chest Physicians. Meta-review suggests a clear benefit of such regimens and supports wider adoption, even when weighed against a small increase in adverse events.

Pre-surgical radiologic identification of peri-prosthetic osteolytic lesions around TKRs: a pre-clinical investigation of diagnostic accuracy

BACKGROUND

Emerging longitudinal data appear to demonstrate an alarming trend towards an increasing prevalence of osteolysis-induced mechanical failure, following total knee replacement (TKR). Even with high-quality multi-plane X-rays, accurate pre-surgical evaluation of osteolytic lesions is often difficult. This is likely to have an impact on surgical management and provides reasonable indication for the development of a model allowing more reliable lesion assessment. The aim of this study, using a simulated cadaver model, was to explore the accuracy of rapid spiral computed tomography (CT) examination in the non-invasive evaluation of peri-prosthetic osteolytic lesions, secondary to TKR, and to compare this to conventional X-ray standards.

METHODS

A series of nine volume-occupying defects, simulating osteolytic lesions, were introduced into three human cadaveric knees, adjacent to the TKR implant components. With implants in situ, each knee was imaged using a two-stage conventional plain X-ray series and rapid-acquisition spiral CT. A beam-hardening artefact removal algorithm was employed to improve CT image quality.After random image sorting, 12 radiologists were independently shown the series of plain X-ray images and asked to note the presence, anatomic location and 'size' of osteolytic lesions observed. The same process was repeated separately for review of the CT images. The corresponding X-ray and CT responses were directly compared to elicit any difference in the ability to demonstrate the presence and size of osteolytic lesions.

RESULTS

Access to CT images significantly improved the accuracy of recognition of peri-prosthetic osteolytic lesions when compared to AP and lateral projections alone (P = 0.008) and with the addition of bi-planar oblique X-rays (P = 0.03). No advantage was obtained in accuracy of identification of such lesions through the introduction of the oblique images when compared with the AP and lateral projections alone (P = 0.13)

CONCLUSION

The findings of this study suggest that peri-prosthetic osteolytic lesions can be reliably described non-invasively using a simple, rapid-acquisition CT-based imaging approach. The low sensitivity of conventional X-ray, even with provision of supplementary bi-planar 45 degrees oblique views, suggests a limited role for use in situ for TKR implant screening where peri-prosthetic osteolytic lesions are clinically suspected. In contrast, the accuracy of CT evaluation, linked to its procedural ease and widespread availability, may provide a more accurate way of evaluating osteolysis around TKRs, at routine orthopaedic follow up. These findings have direct clinical relevance, as accurate early recognition and classification of such lesions influences the timing and aggressiveness of surgical and non-operative management strategies, and also the nature and appropriateness of planned implant revision or joint-salvaging osteotomy procedures.

Determining disk hydration status with a MnCl2-based MR model

PURPOSE

An extensive body of literature demonstrates a strong correlation between intervertebral disk (IVD) hydration status (HS) and functional spinal integrity. However, to date, in vivo IVD HS assessment has relied largely on subjective and nonrepeatable measures. The aim of this study was to establish the consistency of signal homogeneity of a novel semisolid-state manganese chloride (MnCl2)-based phantom for HS correlation using conventional magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Sixteen MnCl2 phantoms, of increasing relative molar concentration (range 0.01 to 2.9 mM), underwent axial MR imaging. Phantom signal-to-noise ratio measures were recorded for each concentration on several sequence types. Coefficient of variance data were calculated to determine the degree of MR signal variation at each concentration.

RESULTS

Analysis of variance testing suggested no significant difference in coefficient of variance data derived from phantom signal intensities using either T1- (P = .13) or T2-weighted sequence types (P = .96), suggesting a high degree of relative signal homogeneity.

CONCLUSIONS

The findings of this study suggest that a MnCl2 phantom combined with a nonfield reactive, semirigid, gelatin suspension media can produce a predictable, concentration-related, homogeneous MR signal response. This may be an appropriate base material for a noninvasive model to allow accurate quantification of the hydration status of the in vivo human IVD.

Occupationally-acquired noise-induced hearing loss: a senseless workplace hazard

OBJECTIVES

Occupational noise-induced hearing loss (ONIHL) describes an acquired hearing deficiency directly attributable to excessive workplace noise exposure. Data suggest that excessive noise attributes to approximately 37% of all adult causes of hearing loss and remains a significant contributor to employment-related morbidity internationally. Typically insidiously-acquired, often without frank progressive symptomatology, regional medical agencies continue to struggle with this potentially debilitating condition. The aim of the study was to provide a synopsis of the current understanding of ONIHL, its impact on individual workers and the wider international community, and to identify barriers to more uniform adoption of personal hearing protection.

MATERIALS AND METHODS

A review of the contemporary literature was performed using defined keyword searches and OVID, PubMed, and Google Scholar as primary electronic search engines.

RESULTS

A number of published works were identified, describing aspects of the relationship between workplace-related noise exposure and subsequent development of employee hearing impairment, which demonstrate an overwhelming gender imbalance, with up to 97% of affected individuals being male. Industry-specific associations (e.g., mining, manufacturing and heavy construction) were well documented, as were links to toxin-specific exposures, in the recognized development of hearing loss. However, evidence of integration of appraisal of the topically-current area of genetic susceptibility was often lacking. Much discordance still exists among international agencies in the prescriptive regulation and enforcement of "safe" exposure limits.

CONCLUSIONS

Despite a high level of public awareness regarding the importance of hearing preservation and increasingly stringent international occupational health, safety and welfare requirements mandating provision of safer work environments, ONIHL continues to be a significant occupational hazard. ONIHL is permanent and may cause significant disability, for which there currently exists no cure, but is largely overtly-preventable. The impact of ONIHL on the global transition toward dominant communication-rich white-collar employment roles is difficult to quantitate, but is likely to be substantive upon the afflicted individual. In the mainstream setting, exposure-avoidance strategies aimed to reduce the incidence of ONIHL remain the focus of public health and occupational medicine approaches.

A MnCl2-based MR signal intensity linear response phantom

PURPOSE

This study aimed to develop a manganese chloride (MnCl2)-based phantom model that would allow progressive quantitative assessment of tissue hydration based on observed magnetic resonance (MR) imaging signal intensity (SI) linearity characteristics.

MATERIALS AND METHODS

The study was performed using a progressive signal refinement technique that allowed development of an imaging tool for semiquantitative sequential discrimination of MR signal responses. A series of 82 phantoms comprising a gelatin-set MnCl2 composite were imaged under basic T1- and T2-weighted conditions. MR SI measurements were taken using region-of-interest selection, and MnCl2 concentrations were adjusted to allow development of a pair of 8-tube phantoms. These phantoms permitted progressive incremental assessment of hydration based on fundamental MR SI response.

RESULTS

Statistical analysis showed that phantom MR signal response linearity can be achieved using the phantoms described under both T1 and T2 imaging conditions, yielding R2 values of 0.97 and 0.94, respectively.

CONCLUSION

This novel MnCl2-based phantom can be used as a noninvasive reference standard for quantitative classification of in vivo tissue hydration based on routine clinical MR imaging sequences. Progressive correlation testing using a human cartilage sample should be performed to further refine the model for clinical application.

Connexin 26 mutations in autosomal recessive deafness disorders: a review

This review explores the association between GJB2 gene mutations, encoding connexin 26 (Cx26), and nonsyndromic hearing loss. Connexins are proteins that form intracellular membrane channels and regulate ion movement between contiguous fluid spaces. A family of autosomal gene mutations has been identified that lead to abnormal connexin expression within the inner ear that are associated with hearing loss. The exact mechanism by which this link is elicited remains unclear. We aim to highlight the clinically underestimated prevalence of GJB2 gene mutations, to explore the influential role of ethnic diversity in mutation frequency, and to provide a framework for hearing specialists in considering the differential diagnosis of nonsyndromic hearing loss. By linking an observed phenotype associated with abnormal Cx26 expression to the current understanding of the biological and genetic basis underlying it will allow a more accurate clinical description of associated hearing loss, and therefore enable more effective patient management and genetic counselling.

Exploring the relationship between impact factor and manuscript rejection rates in radiologic journals

RATIONALE AND OBJECTIVES

Stratifying candidates objectively on the merit of publication portfolios is an onerous and difficult task. Institutional committees are under increasing pressure to rank applicants based on previous achievements for appointments/promotions, funding, and awards, and must do so within unforgiving time constraints. The journal impact factor (IF) has been loosely adopted in many circles for assessing article "quality," circumventing detailed review of individual articles. The premise supporting such practice often hinges on assuming that high-IF journals are harder to publish in, for example, have higher rejection rates (RRs), and therefore, authors achieving publication in such periodicals should be "recognized" for their achievement. There is no evidence of previous research linking IF and RR.

MATERIALS AND METHODS

A subset of Institute for Scientific Information (ISI)-listed radiology journals, for which IF data were available, was identified and a direct-contact survey approach (63.3% response rate) used to ascertain journal manuscript RR.

RESULTS

Of the sample reviewed, the ISI-listed IF values ranged from 4.759 to 0.056 (mean 1.491), and editor-reported manuscript RRs from 80.0% to 8.0% (mean 47.8%). Statistical comparison of IF and RR using linear regression yielded an r2 value of 0.223.

CONCLUSIONS

In summary, this study demonstrates poor linear agreement between IF and RR for manuscripts submitted to peer-reviewed radiology journals. This suggests that journal IF is a poor predictor of RR, and vice versa. This finding may be of interest to institutional committees who have adopted the IF as an indicator of merit in reviewing publication curriculum vitae, and may encourage rethinking of currently practiced candidate assessment approaches.

Effect of bovine colostrum supplementation on the composition of resistance trained and untrained limbs in healthy young men

This study examined the effect of bovine colostrum (BC) supplementation on the tissue composition of resistance trained (T) and untrained (UT) limbs. Using a double-blind design, subjects were randomly allocated to 60 g day(-1) of BC ( n=17) or whey protein (WP) ( n=17) during 8 weeks of resistance training of the elbow flexors (EF) of their non-dominant arm (T). Axial magnetic resonance images of both upper arms, maximal voluntary isometric torque (MVC) of EF, and the one repetition maximum (1RM) for bicep curls were measured pre- and post-supplementation. There were no differences in macronutrient intakes ( P>0.28) or the volume of training completed by T ( P=0.98) between the two groups. T of BC experienced a significantly greater increase in circumference [BC 2.3 (3.0)%, WP 0.0 (4.2)%; P=0.05] and cross-sectional area (CSA) [BC 4.2 (6.0)%, WP -0.2 (8.3)%; P=0.05] compared with WP, due principally to a greater increase in skin and subcutaneous fat (SSF) CSA [BC 5.5 (10.9)%, WP -2.7 (14.1)%; P=0.03]. No tissue compartment changed significantly in UT of either group ( P>0.05). MVC and 1RM increased for T and UT in both groups ( P<0.05), but the increases were not different between groups ( P>0.32). Since the SSF compartment increased in T but not UT, and fat turnover in adipocytes is under hormonal control and would not be localised to one arm, we suggest that the increase in SSF CSA in T of BC may have been due to an increase in skin CSA, rather than fat.

Understanding the limitations of the journal impact factor

The impact factor, a simple mathematical formula reflecting the number of citations of a journal's material divided by the number of citable materials published by that same journal, has evolved to become one of the most influential tools in modern research and academia. The impact factor can be influenced and biased (intentionally or otherwise) by many factors. Extension of the impact factor to the assessment of journal quality or individual authors is inappropriate. Extension of the impact factor to cross-discipline journal comparison is also inappropriate. Those who choose to use the impact factor as a comparative tool should be aware of the nature and premise of its derivation and also of its inherent flaws and practical limitations.

The accuracy of three-dimensional reconstructions of the ovine knee: dissectional validation

A single, complete, ovine knee was imaged using conventional MRI then dissected allowing comprehensive dimensional measurement of the intra-articular structures. A three-dimensional (3-D) computer model of the knee was generated from the MR sections. Thirty-two individual structural measures were recorded from the image output for which there was an available surgical measure for direct comparison. The results of Pearson's correlation testing show a rounded score of 1.00, suggesting an exceptional linear correlation between direct anatomical measurement and the 3-D image output. Further analysis of the data revealed an average error of measurement of 0.2mm across the 32 measures. The findings of this preliminary study suggest that 3-D reconstruction from MR data may be an appropriate, and accurate, means for making dimensional measurements of the bony and soft tissue structures of the ovine knee. It is unlikely that the measurement error would be of any great clinical significance. There is evidence in the literature to suggest that an ovine knee may be considered an acceptable model for substitution for the human knee in diagnostic assessment studies. Therefore, such findings may be considered clinically relevant in the field of human knee assessment.