A review of materials currently used in orbital floor reconstruction

Orbital fractures are common fractures of the midface. As such, numerous techniques and materials exist for the repair of this region, each with inherent advantages and disadvantages. But does the ideal implant material exist? Should we stop and simply use readily available materials, or should the cycle of need and discovery continue? A comprehensive review of materials used in orbital reconstruction and possible new directions in orbital floor reconstruction are presented.

T-cell activation genes differentially expressed at birth in CD4+ T-cells from children who develop IgE food allergy

BACKGROUND

Presymptomatic immaturity in neonatal T-cell function is a consistent antecedent of allergic disease, including reduced responsiveness to polyclonal activation.

METHODS

To elucidate the underlying mechanisms, we examined for differences in T-cell gene expression in longitudinal samples collected at birth and at 1 year of age in children with (n = 30) and without IgE-mediated food allergy (n = 30). We employed a low-level soluble anti-CD3 stimulus to activate the T-cell receptor (TCR) and surveyed gene expression by DNA microarray in purified CD4(+) T-cells. Allergen-specific responses were assessed in parallel functional studies.

RESULTS

At birth, the allergic group showed a reduced number of genes up regulated in response to anti-CD3 treatment on the microarray and a reduced lympho proliferative capacity, suggesting clear differences in T-cell signalling pathways. Polymerase chain reaction (PCR) validation of candidate genes confirmed significantly lower expression of a number of genes in the allergic group including RELB, NFKB2, LIF and FAS. By 12 months of age, there were marked changes in the anti-CD3 response in all infants, culminating in upregulation of cytokine genes (IL-5, IL-13, IL-17 and IL-22). Neonatal differences were no longer apparent. Instead, the allergic group, all symptomatic by this age, showed differential expression of T-cell lineage pathways including GATA-3, MAL and FcER1 in unstimulated T-cells. Allergen stimulation induced significantly higher cytokines production (IL-5, IL-13 and IFNγ) in the allergic group.

CONCLUSION

Although transient, suboptimal neonatal T-cell activation pathways that signal through the NF-κB complex may affect the developmental transition of T-cell phenotypes in the periphery shortly after birth and may increase the risk of food allergy.

Risk compensation in children's activities: A pilot study

BACKGROUND

The intent of protective equipment (PE) in sports and leisure activities is to reduce injuries. However, some postulate that any safety measure prompts riskier behaviour, a phenomenon known as 'risk homeostasis' or 'risk compensation.' This study explores one approach to examining this in children. The rationale for this pilot study was to establish if children between six and 16 years old could answer questions about risk-taking sensibly and which questions, if any, could be eliminated; to establish the reliability of response; and to determine the numbers needed for a definitive study.

METHODS

Sixty-three children with nonsevere injuries, ages six to 16 years, were interviewed while waiting to be seen at the Montreal Children's Hospital emergency department. An interviewer administered a questionnaire comprising three sections. The first part only applied to those who were injured in an activity for which some form of PE was available (n=19). The second part examined customary risk-taking behaviour using the thrill and adventure seeking scales of a standardized questionnaire (Zuckerman) (n=63). The third section posed hypothetical questions about likely risk-taking when using PE to those who had engaged in such activities (n=58).

RESULTS

The approach and questionnaire proved feasible with this age group. The responses suggest that children wearing PE were more likely to report increased risk-taking than those who did not wear PE. For most of the hypothetical questions, the majority also reported changes toward riskier behaviour when using PE. However, those wearing PE scored lower on the thrill and adventure seeking scale, suggesting that they are, by nature, less venturesome.

CONCLUSION

The results indicate that risk compensation may modify the effectiveness of PE for children engaged in sports and leisure activities. Conversely, the findings also suggest that those wearing PE may be a cautious subgroup.

Four-part proximal humeral fractures: diagnosis with the 'sunset' sign on anteroposterior radiograph

INTRODUCTION

Four-part proximal humeral fractures require surgical intervention. However, they can be difficult to diagnose in radiological images. We aim to define a new, easily recognisable, radiological sign as a predictor of four-part fracture of the proximal humerus in a plain anteroposterior radiograph of the shoulder.

PATIENTS AND METHODS

We describe our 'sunset' sign as 'articular surface of humeral head pointing away from the glenoid and tilted upwards, in the presence of a displaced greater tuberosity fracture'. We postulate that a patient with proximal humerus fracture showing this sign has four-part fracture until proven otherwise. Between 2002 and 2006, 80 consecutive patients had surgical treatment of their proximal humeral fractures in our unit. Pre-operative radiographs and operative notes of 79 patients were evaluated independently by three blinded observers. The presence of 'sunset' sign was recorded. Findings were then correlated with the operative diagnoses to confirm whether they were four-part fractures or not. With 95% confidence interval, we calculated the sensitivity, specificity, positive and negative predictive values for our diagnostic sign.

RESULTS

Of 79 patients, 30 displayed 'sunset' sign in their pre-operative radiograph. Of these, 28 had confirmed four-part fractures operatively. The positive predictive value of 'sunset' sign was 93%. The specificity and sensitivity were 95% and 78%, respectively. The sensitivity was affected by eight patients with four-part fractures with displaced articular head fragment which had dropped either medially or posteriorly.

CONCLUSIONS

These results suggest that, in patients with proximal humeral fractures, the presence of 'sunset' sign in the anteroposterior radiograph is a reliable indicator of four-part fracture.

The cutaneous innervation of the dorsal hand: detailed anatomy with clinical implications

PURPOSE

Detailed knowledge of the anatomy of the cutaneous innervation to the dorsal surface of the hand is valuable information. Because surgical access to the wrist often is obtained via the dorsal skin it would be helpful particularly to delineate an area where surgical incisions would not injure underlying nerves.

METHODS

Thirty cadaver forearms were dissected carefully to examine in detail the anatomy of the lateral antebrachial cutaneous nerve, the superficial branch of the radial nerve, and the dorsal branch of the ulnar nerve. Each hand then was evaluated for an area free of any major nerve branches over the dorsal wrist.

RESULTS

Although the innervation to the dorsal hand varies certain patterns exist. The innervation pattern between the superficial branch of the radial nerve and the dorsal branch of the ulnar nerve is distributed evenly, dual innervation is frequent between the 2 nerves, and the lateral antebrachial cutaneous nerve is a common contributor to the innervation of the thumb. The superficial branch of the radial nerve and the dorsal branch of the ulnar nerve have identifiable branching patterns and have been classified according to a system developed for this study.

CONCLUSIONS

Two classification systems based on detailed dorsal hand cutaneous innervation patterns can be used to specify the placement of a safe dorsal skin incision away from major nerve branches.

Open repair of massive rotator cuff tears in patients aged sixty-five years or over: is it worthwhile?

The purpose of the study was to evaluate the functional outcome and identify possible preoperative prognostic factors in patients aged 65 years or over undergoing open repair for a massive (>5 cm) full-thickness rotator cuff tear. Patients were assessed after a mean of 48 months by an independent observer by use of the Constant score and the Oxford Shoulder Questionnaire. The outcome was excellent or good in 44% and poor in 23%. The patient satisfaction rate was 84%. Pain relief was obtained in 93%. We found three preoperative variables to be significantly associated with a poor outcome: female sex, duration of symptoms greater than 34 months before surgery, and American Society of Anesthesiologists grade. The results of our study suggest that appropriately selected patients who are aged 65 years or over with a massive full-thickness rotator cuff tear can be expected to have a good functional outcome and pain relief after repair.

Open repair of massive rotator cuff tears in patients aged sixty-five years or over: is it worthwhile?

The purpose of the study was to evaluate the functional outcome and identify possible preoperative prognostic factors in patients aged 65 years or over undergoing open repair for a massive (>5 cm) full-thickness rotator cuff tear. Patients were assessed after a mean of 48 months by an independent observer by use of the Constant score and the Oxford Shoulder Questionnaire. The outcome was excellent or good in 44% and poor in 23%. The patient satisfaction rate was 84%. Pain relief was obtained in 93%. We found three preoperative variables to be significantly associated with a poor outcome: female sex, duration of symptoms greater than 34 months before surgery, and American Society of Anesthesiologists grade. The results of our study suggest that appropriately selected patients who are aged 65 years or over with a massive full-thickness rotator cuff tear can be expected to have a good functional outcome and pain relief after repair.

The use of polymethyl-methacrylate (Artecoll) as an adjunct to facial reconstruction

BACKGROUND

Injectable polymethyl-methacrylate (PMMA) microspheres, or Artecoll, has been used for the last few years in aesthetic surgery as long-term tissue filler for the correction of wrinkles and for lip augmentation. This paper presents three cases of the use of PMMA microsphere injection for reconstructive patients with defects of varying etiologies. These cases provide examples of a novel adjunct to the repertoire of the reconstructive surgeon.

OBJECTIVES

To evaluate the effectiveness (short- and long-term) of PMMA injection for the correction of small soft tissue defects of the face.

METHODS

Three case histories are presented. They include the origin of the defect; previous reconstructions of the defect; and area, volume, timing and technical particularities of PMMA administration.

RESULTS

All three cases showed improvement of the defect with the PMMA injection with respect to both objective evidence and patient satisfaction. The improvements can still be seen after several years.

CONCLUSIONS

PMMA microsphere injection can be effectively used to correct selected small facial defects in reconstructive cases and the results are long lasting.

Delayed fracture of the ceramic femoral head after trauma

There are various ways in which a total hip arthroplasty may fail catastrophically. Failure of the ceramic femoral head component is well known and described. It may fail because of trauma, but delayed fracture after trauma has not been described previously. This case report describes this phenomenon and postulates a possible mechanism for this failure.

TGFbeta and PTHrP control chondrocyte proliferation by activating cyclin D1 expression

Exact coordination of growth plate chondrocyte proliferation is necessary for normal endochondral bone development and growth. Here we show that PTHrP and TGFbeta control chondrocyte cell cycle progression and proliferation by stimulating signaling pathways that activate transcription from the cyclin D1 promoter. The TGFbeta pathway activates the transcription factor ATF-2, whereas PTHrP uses the related transcription factor CREB, to stimulate cyclin D1 promoter activity via the CRE promoter element. Inhibition of cyclin D1 expression with antisense oligonucleotides causes a delay in progression of chondrocytes through the G1 phase of the cell cycle, reduced E2F activity, and decreased proliferation. Growth plates from cyclin D1-deficient mice display a smaller zone of proliferating chondrocytes, confirming the requirement for cyclin D1 in chondrocyte proliferation in vivo. These data identify the cyclin D1 gene as an essential component of chondrocyte proliferation as well as a fundamental target gene of TGFbeta and PTHrP during skeletal growth.

Measurement of myocardial wall thickening from PET/SPECT images: comparison of two methods

PURPOSE

We compared two methods for measuring myocardial wall thickening from nuclear medicine perfusion scans. The first method uses the percent change in peak activity, and the second method models a profile measured across the myocardium.

METHOD

Mathematical simulations of the myocardium were used. In addition, images with PET or SPECT resolution were created from real MR images. Known amounts of noise were then added.

RESULTS

The percent peak thickening (% PT) is nonlinear with true percent thickening, especially for PET resolutions [7 mm full width at half-maximum (FWHM)]. For the peak method, low levels of noise (10%) introduced an error of 8%PT for PET and of 16%PT for SPECT. Additional smoothing reduced these errors. For the fitted model, at 10% noise, the error in thickening was large: 2.3 mm for PET and 7.8 mm for SPECT.

CONCLUSION

The fitted model works well only with good resolution and low noise (e.g., 7 mm FWHM and 10%). The peak method is also sensitive to noise, especially for poorer resolutions. Additional smoothing gives more reliable results for the peak method but not the fitted method. The peak method is therefore the more generally reliable, but even this method may only allow classification of myocardial thickening into broad categories.

Rotation of Listing's plane during vergence

When visually fixating targets on an isovergence surface, the position of each eye was constrained to a plane. Thus, Listing's law holds during vergence. The planes were, however, rotated temporally with respect to those when viewing distant targets. The effect of this rotation was to produce a torsion which depended on eye elevation; extorsion of the two eyes for downward gaze and intorsion for upward gaze. The saccadic velocity command was relatively unaffected during vergence. Computer simulations suggest that the saccadic tonic command and the vergence command interact multiplicatively in three dimensions.

Convergence of signals in the zona incerta for angiotensin-mediated and osmotic thirst

Extracellular single-unit activity was recorded from 109 neurons in the diencephalon of urethane-anesthetized rats. Injections of angiotensin II (ANG II) into the subfornical organ (SFO) increased the activity of 15 zona incerta (ZI) neurons and decreased the activity of 9. Injections of ANG II into the SFO increased the activity of 8 lateral hypothalamic neurons and decreased the activity of 7. Of the units which responded to the injection of ANG II into the SFO, 9 neurons in the ZI and 5 in the lateral hypothalamus (LH) also responded to injections of hyperosmotic saline into the medial preoptic area. The SFO and preoptic area are possible sites of receptors for ANG II-mediated and osmotic thirst, respectively, and the present results suggest that signals important for the initiation of these thirst mechanisms converge on neurons in the ZI and LH. These findings are discussed in relation to other neural structures that have been implicated in the regulation of water intake.

Contribution of zona incerta to osmotically induced drinking in rats

Spontaneous extracellular activity was recorded from single neurons in the rostral zona incerta (ZI) of urethan-anesthetized rats. Ventricular injections of hyperosmotic saline (1 or 2 microliter of NaCl solutions with osmolarities of 0.6 or 1.2 osmol/l) and distilled water (1 or 2 microliter) at the level of the anteroventral third ventricle (AV3V) changed the firing rate of ZI neurons. By comparison, ventricular injections of osmotic solutions at the level of the dorsal third ventricle were relatively ineffective. Injections of osmotic solutions (0.2 or 0.5 microliter of 1.2 osmol/l NaCl) into the medial preoptic area (MPO) also changed the firing rate of ZI neurons, whereas control injections into the caudate putamen were ineffective. In another series of rats, injections of procaine into the region of the rostral ZI significantly reduced drinking to injections of hyperosmotic saline into the ipsi- but not the contralateral MPO. The ZI, AV3V, and MPO have previously been reported to contribute to the neural regulation of fluid intake. These findings provide additional evidence for a role of the ZI in drinking and suggest that part of the central pathway for osmotic thirst involves a projection to neurons in the ZI from osmoreceptors in the MPO.

Decreased biliary excretion of piperacillin after percutaneous relief of extrahepatic obstructive jaundice

The biliary excretion of piperacillin has been assessed in 11 patients with obstructive jaundice due to hilar cholangiocarcinoma. After a 1-g intravenous dose administered 30 min before preliminary percutaneous transhepatic cholangiography, no drug was detected in the bile of seven patients; in four others, drug concentrations were far below the corresponding level in serum. After a period of external biliary drainage of up to 28 days, levels of antibiotic in bile after intravenous administration were only minimally increased. The results suggest that although the impairment of hepatic function may be improved by external biliary decompression when assessed by a fall in plasma bilirubin, the biliary elimination of piperacillin and related beta-lactam antibiotics may remain impaired for prolonged periods.