Experimental Characterization of the Properties of Double-Lap Needled and Hybrid Joints of Carbon/Epoxy Composites

The effect of through-thickness reinforcement by thin 1 mm steel needles (z-pins) on the static tensile strength of double-lap joints of a carbon/epoxy composite was investigated. Two types of joints—z-pinned and hybrid (including glued ones)—were considered. The joints were reinforced in the overlap region with 9, 25, or 36 z-pins. Comparing mechanical properties of the double-lap joints with the corresponding characteristics of their unpinned counterparts, the z-pins were found to be highly effective: the strength and stiffness of the pinned joints increased up to 300% and 280%, respectively. These improvements were due to a transition in the failure mechanism from debonding of the joint in the absence of z-pins to pullout or shear rupture of z-pins or to the tensile failure of laminate adherends, depending on the volume content of the pins.

Diagnosis, treatment and clinical perspectives of acromegaly

Acromegaly is an insidious disease of the pituitary caused by a growth hormone-secreting adenoma. Generally, the diagnosis is made rather late in the course of the disease. Currently, acromegaly can be cured in about half of the patients with the disease by expert surgery. The remainder of non-surgically cured patients often can be effectively treated with somatostatin analogs; either with the new generation of dopaminergic drugs or with Pegvisomant, a GH-receptor blocking agent. However, at the time of diagnosis many patients suffer from serious comorbidities, including hypertension, heart disease, arthrosis, sleep apnea and diabetes mellitus. Recent reports have shown that mortality risk can be normalized. Nevertheless, all efforts should be undertaken to treat comorbidities. New strategies for surgery and medical treatment are discussed.

Contrast-enhanced MRI of the temporomandibular joint: findings in children without juvenile idiopathic arthritis

BACKGROUND

Contrast-enhanced magnetic resonance imaging (MRI) is highly sensitive for assessing temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA), but only sparse data exist on normal TMJ appearance in children.

PURPOSE

To determine normal MRI appearance and enhancement pattern of pediatric TMJ as basis for diagnosing early arthritis.

MATERIAL AND METHODS

In 27 children (age range, 1.2-16.8 years) without TMJ pathology undergoing head MRI, fat-saturated T2-weighted (T2W) and postcontrast fat-saturated T1-weighted (T1W) images sagittally aligned to the 54 TMJs, besides standard T1W and T2W images, were assessed for bony and soft tissue signal intensity (SI), the amount of perceptible joint fluid, and contrast enhancement (CE).

RESULTS

Bone marrow SI and CE of the mandible were consistent with varying degrees of residual red marrow in 96% of joints. The mandibular condyles were mostly isointense to the ramus, but in 9% showed mild edema-like bone marrow SI and CE. Small amounts of intraarticular fluid were detected in 31% on T2W images without fat saturation and in 83% on T2W images with fat saturation as fine lines in the upper or lower joint compartment or as small dots in an articular recess. Seventy-nine percent of all TMJs showed intense joint enhancement on early images restricted to areas of intraarticular fluid.

CONCLUSION

Small amounts of joint fluid with intense CE are a common MRI finding in TMJs of children without JIA and therefore should not be considered diagnostic for early arthritis.

Calcitonin gene-related peptide in the joint: contributions to pain and inflammation

Arthritis is the commonest cause of disabling chronic pain, and both osteoarthritis (OA) and rheumatoid arthritis (RA) remain major burdens on both individuals and society. Peripheral release of calcitonin gene-related peptide (CGRP) contributes to the vasodilation of acute neurogenic inflammation. Contributions of CGRP to the pain and inflammation of chronic arthritis, however, are only recently being elucidated. Animal models of arthritis are revealing the molecular and pathophysiological events that accompany and lead to progression of both arthritis and pain. Peripheral actions of CGRP in the joint might contribute to both inflammation and joint afferent sensitization. CGRP and its specific receptors are expressed in joint afferents and up-regulated following arthritis induction. Peripheral CGRP release results in activation of synovial vascular cells, through which acute vasodilatation is followed by endothelial cell proliferation and angiogenesis, key features of chronic inflammation. Local administration of CGRP to the knee also increases mechanosensitivity of joint afferents, mimicking peripheral sensitization seen in arthritic joints. Increased mechanosensitivity in OA knees and pain behaviour can be reduced by peripherally acting CGRP receptor antagonists. Effects of CGRP pathway blockade on arthritic joint afferents, but not in normal joints, suggest contributions to sensitization rather than normal joint nociception. CGRP therefore might make key contributions to the transition from normal to persistent synovitis, and the progression from nociception to sensitization. Targeting CGRP or its receptors within joint tissues to prevent these undesirable transitions during early arthritis, or suppress them in established disease, might prevent persistent inflammation and relieve arthritis pain.

Characteristics of stabilizer muscles: a systematic review

PURPOSE

To identify the main characteristics, based on available evidence, of stabilizer muscles to inform the development of a definition of stabilizer muscles.

METHODS

Electronic databases were systematically searched for relevant literature from the databases' inception to June 2013 using keywords related to stability, muscles, and characteristics of stabilizer muscles. Studies that provided at least one characteristic of a stabilizer muscle were included. For the quality assessment, all included articles were categorized as either experimental or opinion-based studies. Methodological quality was assessed using a customized checklist, and data were analyzed with a narrative synthesis involving content analysis. The number of articles providing either direct evidence supporting a link between the characteristic and joint stability or indirect evidence that a muscle considered to be a stabilizer has that characteristic determined the level of significance of that characteristic for stabilizer muscles.

RESULTS

A total of 77 studies met the inclusion criteria. The highest number of articles providing supporting evidence that a particular muscle characteristic plays a stabilizing role related to biomechanical characteristics (27 articles), followed by neurological characteristics (22 articles) and anatomical/physiological characteristics (4 articles).

CONCLUSION

Based on a synthesis of supporting evidence from the literature, stabilizer muscles can be defined as muscles that contribute to joint stiffness by co-contraction and show an early onset of activation in response to perturbation via either a feed-forward or a feedback control mechanism. These results may guide researchers to investigate which muscles exhibit these characteristics to determine whether particular muscles have a stabilizer rather than a prime mover role during normal functioning.

Sonography of the first metatarsophalangeal joint and sonographically guided intraarticular injection of corticosteroid in acute gout attack

OBJECTIVE

The aims of this study were to identify the characteristic ultrasound (US) findings of the first metatarsophalangeal joint (MTPJ1) in acute gout attack and to evaluate the efficacy and safety of US-guided intraarticular corticosteroid injection of the MTPJ1.

METHODS

We enrolled 21 patients with acute gout attack involving the MTPJ1 unilaterally. US evaluation of each affected MTPJ1 was compared with radiographic features. US-guided intraarticular corticosteroid (0.5 ml [20 mg] of triamcinolone mixed with 0.5 ml of 2% lidocaine) was injected into the affected MTPJ1s. Pain, general disability, and walking disability were assessed at baseline, 24 hours, 48 hours, and 7 days after injection with visual analog scales.

RESULTS

The characteristic US findings of MTPJ1 were erosion, joint effusion, synovial hypertrophy, tophus-like lesion, double contour, hyperechoic spots, and increased power Doppler signal in acute gout attack. US was more sensitive than conventional radiograph in detecting erosion and tophus-like lesion. The reductions of mean visual analog scale scores in pain, general disability, and walking disability were 48 mm (SD, 27), 35 mm (SD, 26) and 39 mm (SD, 26), respectively, 48 hours after US-guided intraarticular corticosteroid injection. There were no adverse events.

CONCLUSIONS

US is a sensitive tool to evaluate joint abnormality of the MTPJ1 in acute gout attack and US-guided intraarticular corticosteroid injection to this joint is effective and safe.

Changes in fatigue, multiplanar knee laxity, and landing biomechanics during intermittent exercise

CONTEXT

Knee laxity increases during exercise. However, no one, to our knowledge, has examined whether these increases contribute to higher-risk landing biomechanics during prolonged, fatiguing exercise.

OBJECTIVES

To examine associations between changes in fatigue (measured as sprint time [SPTIME]), multiplanar knee laxity (anterior-posterior [APLAX], varus-valgus [VVLAX] knee laxity, and internal-external rotation [IERLAX]) knee laxity and landing biomechanics during prolonged, intermittent exercise.

DESIGN

Descriptive laboratory study.

SETTING

Laboratory and gymnasium.

PATIENTS OR OTHER PARTICIPANTS

A total of 30 male (age = 20.3 ± 2.0 years, height = 1.79 ± 0.05 m, mass = 75.2 ± 7.2 kg) and 29 female (age = 20.5 ± 2.3 years, height = 1.67 ± 0.08 m, mass = 61.8 ± 9.0 kg) competitive athletes.

INTERVENTION(S)

A 90-minute intermittent exercise protocol (IEP) designed to simulate the physiologic and biomechanical demands of a soccer match.

MAIN OUTCOME MEASURE(S)

We measured SPTIME, APLAX, and landing biomechanics before and after warm-up, every 15 minutes during the IEP, and every 15 minutes for 1 hour after the IEP. We measured VVLAX and IERLAX before and after the warm-up, at 45 and 90 minutes during the IEP, and at 30 minutes after the IEP. We used hierarchical linear modeling to examine associations between exercise-related changes in SPTIME and knee laxity with exercise-related changes in landing biomechanics while controlling for initial (before warm-up) knee laxity.

RESULTS

We found that SPTIME had a more global effect on landing biomechanics in women than in men, resulting in a more upright landing and a reduction in landing forces and out-of-plane motions about the knee. As APLAX increased with exercise, women increased their knee internal-rotation motion (P = .02), and men increased their hip-flexion motion and energy-absorption (P = .006) and knee-extensor loads (P = .04). As VVLAX and IERLAX increased, women went through greater knee-valgus motion and dorsiflexion and absorbed more energy at the knee (P ≤ .05), whereas men were positioned in greater hip external and knee internal rotation and knee valgus throughout the landing (P = .03). The observed fatigue- and laxity-related changes in landing biomechanics during exercise often depended on initial knee laxity.

CONCLUSIONS

Both exercise-related changes in fatigue and knee laxity were associated with higher-risk landing biomechanics during prolonged exercise. These relationships were more pronounced in participants with greater initial knee laxity.

Fracture-dislocations of the carpometacarpal joints of the ring and little finger

We report the functional and radiographic results of 16 patients with fracture-dislocations of the ring and little finger carpometacarpal joints and 23 cases with fracture-dislocations of only the little finger carpometacarpal joint treated between 2006 and 2012. The above two cohort populations of patients were treated with either open reduction and pin fixation or closed reduction and pin fixation. These patients were followed for a mean of 13 months (range 9 to 48). The DASH scores for patients with fracture-dislocations of the ring and little finger carpometacarpal joints were 6.0 and of the little finger carpometacarpal joint 7.2. We found no functional differences in term of DASH scores after treatment between patients with fracture-dislocations of only the little finger carpometacarpal joint and both the ring and little finger carpometacarpal joints.

Osteoarthritis in young, active, and athletic individuals

Osteoarthritis (OA) is one of the most devastating chronic conditions that affect people around the world. Although the usual population associated with the condition is the elderly, who are mostly inactive, athletes and younger individuals are also susceptible. Depending on the population, the etiology may differ; injuries, occupational activities, and obesity appear to be the most common causes of OA in young and athletic populations. Diagnosing OA in athletes and young individuals is sometimes challenging because of their increased pain tolerance. However, the treatment of OA in these populations does not differ from its management in the general population. Several considerations need to be taken into account when choosing a treatment modality. The purpose of this review is to address OA in athletes and younger individuals and to discuss its presentation, diagnosis, and treatment.

Influence of Column Axial Load and Heat Affected Zone on the Strength of Aluminium Column Web in Tension

The component method for aluminium joints has been recently introduced in some codes and guidelines. Nevertheless, it is still in need of some development and improvement, as in some cases it was obtained by adapting the existing formulations that are valid for steel. The current paper presents the main outcomes of a parametric analysis carried out by means of finite element (FE) numerical models for determining the influence of both column axial load and heat affected zone—in the case of welded details—on the structural response of the column web in a tension component. The proposed study integrates previous research carried out by the authors, where the influence of the assumed alloy was investigated and interpreted by corrective parameters expressed as a function of both the material strain hardening and ductility.

Purinergic signalling in the musculoskeletal system

It is now widely recognised that extracellular nucleotides, signalling via purinergic receptors, participate in numerous biological processes in most tissues. It has become evident that extracellular nucleotides have significant regulatory effects in the musculoskeletal system. In early development, ATP released from motor nerves along with acetylcholine acts as a cotransmitter in neuromuscular transmission; in mature animals, ATP functions as a neuromodulator. Purinergic receptors expressed by skeletal muscle and satellite cells play important pathophysiological roles in their development or repair. In many cell types, expression of purinergic receptors is often dependent on differentiation. For example, sequential expression of P2X5, P2Y1 and P2X2 receptors occurs during muscle regeneration in the mdx model of muscular dystrophy. In bone and cartilage cells, the functional effects of purinergic signalling appear to be largely negative. ATP stimulates the formation and activation of osteoclasts, the bone-destroying cells. Another role appears to be as a potent local inhibitor of mineralisation. In osteoblasts, the bone-forming cells, ATP acts via P2 receptors to limit bone mineralisation by inhibiting alkaline phosphatase expression and activity. Extracellular ATP additionally exerts significant effects on mineralisation via its hydrolysis product, pyrophosphate. Evidence now suggests that purinergic signalling is potentially important in several bone and joint disorders including osteoporosis, rheumatoid arthritis and cancers. Strategies for future musculoskeletal therapies might involve modulation of purinergic receptor function or of the ecto-nucleotidases responsible for ATP breakdown or ATP transport inhibitors.

Temporal cytokine expression and the target organ attributes unravel novel aspects of autoimmune arthritis

Susceptibility to autoimmunity is determined by multiple factors. Defining the contribution of the quantitative versus qualitative aspects of antigen-directed immune responses as well as the factors influencing target organ susceptibility is vital to advancing the understanding of the pathogenesis of autoimmunity. In a series of studies, we have addressed these issues using the adjuvant-induced arthritis (AA) model of human rheumatoid arthritis (RA). Lewis rats are susceptible to AA following immunization with heat-killed Mycobacterium tuberculosis H37Ra, whereas Wistar-Kyoto (WKY) rats of the same MHC (major histocompatibility complex) haplotype are resistant. Comparative studies on these and other susceptible/resistant rodent strains have offered interesting insights into differential cytokine responses in the face of comparable T cell proliferative response to the disease relevant antigens. Study of the cytokine kinetics have also permitted validation of the disease-protective versus disease-aggravating effects of specific cytokines by treatment of rats/mice with those cytokines at different phases of the disease. In regard to the target organ attributes, the migration of arthritogenic leukocytes into the joints; the expression of mediators of inflammation, angiogenesis, and tissue damage; the role of vascular permeability; and the characteristics of vascular endothelial cells have been examined. Further, various inhibitors of angiogenesis are effective in suppressing arthritis. Taken together, the differential cytokine responses and unique attributes of the target organ have revealed novel aspects of disease susceptibility and joint damage in AA. The translation of this basic research in animal models to RA patients would not only advance our understanding of the disease process, but also offer novel avenues for immunomodulation of this disease.

Ultrasound versus palpation guidance for intra-articular injections in patients with degenerative osteoarthritis of the elbow

OBJECTIVES

The aim of this study is to evaluate the accuracy rate of ultrasound (US) -guided intra-articular (IA) injections in patients by posterior approach with osteoarthritis (OA) of the elbow.

METHODS

Eighty patients with physical examination and radiographic findings of elbow OA were included. After US-guided IA or palpation-guided IA injection of iohexol contrast by posterior approach into the elbow joint, fluoroscopic images were obtained to ascertain whether the injected material had reached the IA space.

RESULTS

Of the 40 injections performed by US guidance, 40 were confirmed to have been placed in the IA space (an accuracy rate of 100%). Thirty-one of the 40 injections performed by the palpation guidance were IA space (77.5% accuracy rate).

CONCLUSIONS

US-guided IA elbow injections by posterior approach may raise the accuracy rate in elbow joint injections.

A systematic review of MR imaging as a tool for evaluating haemophilic arthropathy in children

Our purposes were to determine: (i) whether there is direct evidence that currently available MRI techniques are accurate for early diagnosis of pathological findings in haemophilic arthropathy; (ii) whether there is an MRI scoring system that best correlates with clinical/radiological constructs for evaluation of haemophilic arthropathy; (iii) whether there is an MRI scoring system that best correlates with clinical/radiological constructs for evaluation of haemophilic arthropathy. Articles were screened using MEDLINE (n = 566), EMBASE (n = 201), and the Cochrane Library (n = 1). Two independent reviewers assessed articles for inclusion under the overarching purposes of the review by using the Standards for Reporting of Diagnostic Accuracy (STARD) tool, and the quality of the studies were graded using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. The electronic literature search retrieved 777 references (after duplicates were removed). A total of 32 studies were chosen for inclusion from the results of the search and review of bibliographical references. Using the STARD tool, seven studies were of excellent quality of reporting, and using the QUADAS-2 tool, 10 studies were judged to be of adequate quality. There is 'fair' evidence to recommend MRI as an accurate test for detecting evidence of haemophilic arthropathy and the use of second or third generation MRI scales for assessing haemophilic arthropathy. However, there is no evidence that screening of early intra-articular soft tissue bleed with MRI improves the functional status of joints over time.

Elucidating the scapulo-humeral rhythm calculation: 3D joint contribution method

The scapulo-humeral rhythm quantifies shoulder joint coordination during arm elevation. The common method calculates a ratio of gleno-humeral (GH) elevation to scapulo-thoracic upward rotation angles. However the other rotations also contribute to arm elevation. The objective is to propose a 3D dynamic scapulo-humeral rhythm calculation method including all rotations of the shoulder joints and compare with the common method. Twenty-nine skin markers were placed on the trunk and dominant arm of 14 healthy males to measure shoulder kinematics. Two-way repeated measures ANOVAs were applied to compare the two methods of calculation of joint contributions and scapulo-humeral rhythm during arm elevation. Significant main effects (p < 0.05) were observed between methods in joint contribution angles and scapulo-humeral rhythms. A systematic overestimation of the GH contribution was observed when only using the GH elevation angle because the scapula is moved outside a vertical plane. Hence, the proposed 3D method to calculate the scapulo-humeral rhythm allows an improved functional shoulder evaluation.

Application of advanced magnetic resonance imaging techniques in evaluation of the lower extremity

This article reviews current magnetic resonance imaging (MR imaging) techniques for imaging the lower extremity, focusing on imaging of the knee, ankle, and hip joints. Recent advancements in MR imaging include imaging at 7 T, using multiple receiver channels, T2* imaging, and metal suppression techniques, allowing more detailed visualization of complex anatomy, evaluation of morphologic changes within articular cartilage, and imaging around orthopedic hardware.

Efficacy of musculoskeletal injections by primary care providers in the office: a retrospective cohort study

BACKGROUND

Musculoskeletal joint pain of varied etiology can be diagnosed and treated with joint and soft-tissue corticosteroid injections.

PURPOSE

The purpose of our study was to compare patients' bodily pain and quality of life (QOL), in addition to the procedural benefit and patient satisfaction, before and after musculoskeletal injections in the office setting.

PATIENTS AND METHODS

Patients were eligible for recruitment if they were over age 18 and had an injection for musculoskeletal pain from a primary care provider in an office procedural practice. Included in our analysis were knee joint/bursa, trochanteric bursa, and shoulder joint/bursa injection sites. The variables measured were pain, benefit from the injection, QOL physical and mental components, and patient satisfaction. This was a retrospective cohort study approved by the institutional review board.

RESULTS

Patients' pain was assessed by the patients using a six-point Likert scale (none, very mild, mild, moderate, severe, and very severe). We noted that self-perception of pain decreased from 3.10 (± standard deviation at baseline 0.96) before to 2.36 (± standard deviation after the infection 1.21) (P = 0.0001) after the injection. In terms of the impact on QOL, our patients had a pre-injection physical score of 37.25 ± 8.39 and a mental score at 52.81 ± 8.98. After the injections, the physical score improved to 42.35 ± 9.07 (P = 0.0001) and the mental to 53.54 ± 8.20 (P = 0.0001) for the overall group. Ninety-six percent of the patients reported they were satisfied or extremely satisfied in the procedure clinic.

CONCLUSION

In this study, we found significant pain relief and improved physical QOL in patients undergoing an injection in the knee joint/bursa, shoulder joint/bursa, or trochanteric bursa by primary care providers in the office setting.

ISHKS joint registry: A preliminary report

BACKGROUND

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are the most widely practiced surgical options for arthritis all over the world and its application is rising in India. Indian Society of Hip and Knee Surgeons (ISHKS) has established a joints registry and has been collecting data for last 6 years.

MATERIALS & METHODS

All members of ISHKS are encouraged to actively participate in the registry. A simple two page knee and hip form can be downloaded from the website www.ishks.com. The information collected includes patient demographics, indication for surgery, implant details and in case of revision arthroplasty: the details of implants removed and the cause of failure of primary arthroplasty. These forms are mailed to the central registry office and the data is fed in computerized registry. Data collection started in October 2006.

RESULTS

Joint registry is a very important initiative of ISHKS and till date, have data of 34,478 TKAs and 3604 THAs, contributed by 42 surgeons across India. Some important observations have emerged. Data of 34,478 TKAs was assessed: These included 8612 males (25%) and 25,866 females (75%). Average age was 64.4 years (Osteoarthritis range: 45 to 88 years; Rheumatoid arthritis range: 22 to 74 years). Average body mass index was 29.1 (Range: 18.1 to 42.9). The indication for TKA was osteoarthritis in 33,444 (97%) and rheumatoid arthritis in 759 (2.2%). Total of 3604 THA procedures were recorded. These included 2162 (60%) male patients and 1442 (40%) female patients. Average age was 52 years (Range 17 to 85 years) and average BMI was 25.8 (Range: 17.3 to 38.5). The indications for THA was AVN in 49%.

CONCLUSION

The registry will become more meaningful in years to come. Active participation of all arthroplasty surgeons across India is vital for the success of the joints registry.

Knuckle pads - a rare finding

Knuckle pads are rare harmless subcutaneous nodules that must be differentiated from joint disease of the proximal interphalangeal or rarely of the metacarpophalangeal joints as well as from other masses of the paraarticular tissues. We present a case of an otherwise healthy 36-year-old woman presenting with bilateral knuckle pads located at the dorsal aspect of the proximal interphalangeal joints. No predisposition to a specific musculoskeletal disorder was noted. Ultrasound revealed well-delimited subcutaneous hypoechoic masses without internal flow signals at color Doppler. Histology showed proliferation of myofibroblasts with a decrease of elastic filaments in the deep dermis. The clinical picture, the family history in addition to the histology allowed us to make the diagnosis of knuckle pads. We present the ultrasound findings of knuckle pads and discuss the differential diagnosis of a “swelling” in the dorsal region of proximal interphalangeal joints and metacarpophalangeal joints.

Differential limb loading in miniature pigs (Sus scrofa domesticus): a test of chondral modeling theory

Variation in mechanical loading is known to influence chondrogenesis during joint formation. However, the interaction among chondrocyte behavior and variation in activity patterns is incompletely understood, hindering our knowledge of limb ontogeny and function. Here, the role of endurance exercise in the development of articular and physeal cartilage in the humeral head was examined in 14 miniature swine (Sus scrofa domesticus). One group was subjected to graded treadmill running over a period of 17 weeks. A matched sedentary group was confined to individual pens. Hematoxylin and eosin staining was performed for histomorphometry of cartilage zone thickness, chondrocyte count and cell area, with these parameters compared multivariately between exercised and sedentary groups. Comparisons were also made with femora from the same sample, focusing on humerus-femur differences between exercised and sedentary groups, within-cohort comparisons of humerus-femur responses and correlated changes within and across joints. This study shows conflicting support for the chondral modeling theory. The humeral articular cartilage of exercised pigs was thinner than that of sedentary pigs, but their physeal cartilage was thicker. While articular and physeal cartilage demonstrated between-cohort differences, humeral physeal cartilage exhibited load-induced responses of greater magnitude than humeral articular cartilage. Controlling for cohort, the humerus showed increased chondrocyte mitosis and cell area, presumably due to relatively greater loading than the femur. This represents the first known effort to evaluate chondral modeling across multiple joints from the same individuals. Our findings suggest the chondral response to elevated loading is complex, varying within and among joints. This has important implications for understanding joint biomechanics and development.

Whole blood lead levels are associated with biomarkers of joint tissue metabolism in African American and white men and women: the Johnston County Osteoarthritis Project

PURPOSE

To examine associations between biomarkers of joint tissue metabolism and whole blood lead (Pb), separately for men and women in an African American and Caucasian population, which may reflect an underlying pathology.

METHODS

Participants in the Johnston County Osteoarthritis Project Metals Exposure Sub-Study (329 men and 342 women) underwent assessment of whole blood Pb and biochemical biomarkers of joint tissue metabolism. Urinary cross-linked N telopeptide of type I collagen (uNTX-I) and C-telopeptide fragments of type II collagen (uCTX-II), serum cleavage neoepitope of type II collagen (C2C), serum type II procollagen synthesis C-propeptide (CPII), and serum hyaluronic acid (HA) were measured using commercially available kits; the ratio of [C2C:CPII] was calculated. Serum cartilage oligomeric matrix protein (COMP) was measured by an in-house assay. Multiple linear regression models were used to examine associations between continuous blood Pb and biomarker outcomes, adjusted for age, race, current smoking status, and body mass index. Results are reported as estimated change in biomarker level for a 5-unit change in Pb level.

RESULTS

The median Pb level among men and women was 2.2 and 1.9μg/dL, respectively. Correlations were noted between Pb levels and the biomarkers uNTX-I, uCTX-II, and COMP in women, and between Pb and uCTX-II, COMP, CPII, and the ratio [C2C:CPII] in men. In adjusted models among women, a 5-unit increase in blood Pb level was associated with a 28% increase in uCTX-II and a 45% increase in uNTX-I levels (uCTX-II: 1.28 [95% CI: 1.04-1.58], uNTX-I: 1.45 [95% CI:1.21-1.74]). Among men, levels of Pb and COMP showed a borderline positive association (8% increase in COMP for a 5-unit change in Pb: 1.08 [95% CI: 1.00-1.18]); no other associations were significant after adjustment.

CONCLUSIONS

Based upon known biomarker origins, the novel associations between blood Pb and biomarkers appear to be primarily reflective of relationships to bone and calcified cartilage turnover among women and cartilage metabolism among men, suggesting a potential gender-specific effect of Pb on joint tissue metabolism that may be relevant to osteoarthritis.

Tarsal-less peptides control Notch signalling through the Shavenbaby transcription factor

The formation of signalling boundaries is one of the strategies employed by the Notch (N) pathway to give rise to two distinct signalling populations of cells. Unravelling the mechanisms involved in the regulation of these signalling boundaries is essential to understanding the role of N during development and diseases. The function of N in the segmentation of the Drosophila leg provides a good system to pursue these mechanisms at the molecular level. Transcriptional and post-transcriptional regulation of the N ligands, Serrate (Ser) and Delta (Dl) generates a signalling boundary that allows the directional activation of N in the distalmost part of the segment, the presumptive joint. A negative feedback loop between odd-skipped-related genes and the N pathway maintains this signalling boundary throughout development in the true joints. However, the mechanisms controlling N signalling boundaries in the tarsal joints are unknown. Here we show that the non-canonical tarsal-less (tal) gene (also known as pri), which encodes for four small related peptides, is expressed in the N-activated region and required for joint development in the tarsi during pupal development. This function of tal is both temporally and functionally separate from the tal-mediated tarsal intercalation during mid-third instar that we reported previously. In the pupal function described here, N signalling activates tal expression and reciprocally Tal peptides feedback on N by repressing the transcription of Dl in the tarsal joints. This Tal-induced repression of Dl is mediated by the post-transcriptional activation of the Shavenbaby transcription factor, in a similar manner as it has been recently described in the embryo. Thus, a negative feedback loop involving Tal regulates the formation and maintenance of a Dl+/Dl- boundary in the tarsal segments highlighting an ancient mechanism for the regulation of N signalling based on the action of small cell signalling peptides.

Mechanobiology of embryonic skeletal development: Insights from animal models

A range of clinical conditions in which fetal movement is reduced or prevented can have a severe effect on skeletal development. Animal models have been instrumental to our understanding of the interplay between mechanical forces and skeletal development, particularly the mouse and the chick model systems. In the chick, the most commonly used means of altering the mechanical environment is by pharmaceutical agents which induce paralysis, whereas genetically modified mice with nonfunctional or absent skeletal muscle offer a valuable tool for examining the interplay between muscle forces and skeletogenesis in mammals. This article reviews the body of research on animal models of bone or joint formation in vivo in the presence of an altered or abnormal mechanical environment. In both immobilized chicks and "muscleless limb" mice, a range of effects are seen, such as shorter rudiments with less bone formation, changes in rudiment and joint shape, and abnormal joint cavitation. However, although all bones and synovial joints are affected in immobilized chicks, some rudiments and joints are unaffected in muscleless mice. We propose that extrinsic mechanical forces from movements of the mother or littermates impact on skeletogenesis in mammals, whereas the chick embryo is reliant on intrinsic movement for mechanical stimulation. The insights gained from animal models into the mechanobiology of embryonic skeletal development could provide valuable cues to prospective tissue engineers of cartilage and bone and contribute to new or improved treatments to minimize the impact on skeletal development of reduced movement in utero.

Pretreatment of periosteum with TGF-beta1 in situ enhances the quality of osteochondral tissue regenerated from transplanted periosteal grafts in adult rabbits

OBJECTIVE

To compare the efficacy of in situ transforming growth factor-beta1 (TGF-beta1)-pretreated periosteum to untreated periosteum for regeneration of osteochondral tissue in rabbits.

METHODS

In the pretreatment group, 12 month-old New Zealand white rabbits received subperiosteal injections of 200 ng of TGF-beta1 percutaneously in the medial side of the proximal tibia, 7 days prior to surgery. Control rabbits received no treatment prior surgery. Osteochondral transverse defects measuring 5mm proximal to distal and spanning the entire width of the patellar groove were created and repaired with untreated or TGF-beta1-pretreated periosteal grafts. Post-operatively the rabbits resumed normal cage activity for 6 weeks.

RESULTS

Complete filling of the defects with regenerated tissue was observed in both the TGF-beta1-pretreated and control groups with reformation of the original contours of the patellar groove. The total histological score (modified O'Driscoll) in the TGF-beta1-pretreated group, 20 (95% Confidence Interval (CI), 19-21), was significantly higher (P=0.0001) than the control group, 18 (16-19). The most notable improvements were in structural integrity and subchondral bone regeneration. No significant differences in glycosaminoglycan or type II collagen content, or equilibrium modulus were found between the surgical groups. The cambium of the periosteum regenerated at the graft harvest site was significantly thicker (P=0.0065) in the TGF-beta1-pretreated rabbits, 121 microm (94-149), compared to controls, 74 microm (52-96), after 6 weeks.

CONCLUSIONS

This study demonstrates that in situ pretreatment of periosteum with TGF-beta1 improves osteochondral tissue regeneration at 6-weeks post-op compared to untreated periosteum in 12 month-old rabbits.

Measuring musculoskeletal symptoms in cancer survivors who receive hematopoietic cell transplantation

INTRODUCTION

Beyond documentation of high prevalence rates, research has not examined the qualities and characteristics of musculoskeletal symptoms in cancer survivors, possibly because measures have not been validated specifically for the assessment of these symptoms in survivors. We report here on a new measure of muscle and joint symptoms for survivors of hematologic malignancies and hematopoietic cell transplantation (HCT).

METHODS

In a cross-sectional design, 130 adults, 5-20 years after HCT, completed patient-reported outcomes. Assessment included musculoskeletal symptoms on the Muscle and Joint Measure (MJM), as well as health-related quality of life and treatments.

RESULTS

Principal components analysis using promax rotation revealed four subscales for the MJM with item factor loadings above 0.50: muscle aches or stiffness (myalgias), joint pain, stiffness or swelling (arthralgias), muscle cramps, and muscle weakness. Variance explained by the total score was 77%. Internal consistency reliabilities of the subscales and total score ranged from 0.86 to 0.93. Validity was confirmed by correlations with the Short Form-36 bodily pain, physical function and vitality subscales, the Fatigue Symptom Inventory, and the Symptom Checklist-90-R depression (all P < .001).

CONCLUSIONS

Musculoskeletal symptoms in survivors who received HCT can be measured reliably and validly with the MJM. The measure requires testing to establish its psychometric properties with other diagnostic and treatment groups.

IMPLICATIONS FOR CANCER SURVIVORS

The MJM has potential research and clinical value for addressing the musculoskeletal symptoms of survivors. The measure may assist with examining the mechanisms as well as treatments for these symptoms, which are among the most prevalent in long-term cancer survivors.