Evolution of surface morphology of Er:YAG laser-machined human bone.

The extensive research on the laser machining of the bone has been, so far, restricted to drilling and cutting that is one- and two-dimensional machining, respectively. In addition, the surface morphology of the laser machined region has rarely been explored in detail. In view of this, the current work employed three-dimensional laser machining of human bone and reports the distinct surface morphology produced within a laser machined region of human bone. Three-dimensional laser machining was carried out using multiple partially overlapped pulses and laser tracks with a separation of 0.3 mm between the centers of consecutive laser tracks to remove a bulk volume of the bone. In this study, a diode-pumped pulse Er:YAG laser (λ = 2940 nm) was employed with continuously sprayed chilled water at the irradiation site. The resulting surface morphology evolved within the laser-machined region of the bone was evaluated using scanning electron microscopy, energy dispersive spectroscopy, and X-ray micro-computed tomography. The distinct surface morphology involved cellular/channeled scaffold structure characterized by interconnected pores surrounded by solid ridges, produced within a laser machined region of human structural bone. Underlying physical phenomena responsible for evolution of such morphology have been proposed and explained with the help of a thermokinetic model.

Thermal Assessment of Ex Vivo Laser Ablation of Cortical Bone.

As a potential osteotomy tool, laser ablation is expected to provide rapid machining of bone, while generating minimal thermal damage (carbonization) and physical attributes within the machined region conducive to healing. As these characteristics vary with laser parameters and modes of laser operation, the clinical trials and in vivo studies render it difficult to explore these aspects for optimization of the laser machining parameters. In light of this, the current work explores various thermal and microstructural aspects of laser-ablated cortical bone in ex vivo study to understand the fundamentals of laser-bone interaction using computational modeling. The study employs the Yb-fiber Nd:YAG laser (λ = 1064 nm) in the continuous wave mode to machine the femur section of bovine bone by a three-dimensional machining approach. The examination involved thermal analysis using differential scanning calorimetry and thermogravimetry, phase analysis using X-ray diffractometry, qualitative analysis using X-ray photoelectron spectroscopy, and microstructural and semiquantitative analysis using scanning electron microscopy equipped with energy-dispersive spectrometry. The mechanism of efficient bone ablation using the Nd:YAG laser was evaluated using the computational thermokinetics outcome. The use of high laser fluence (10.61 J/mm2) was observed to be efficient to reduce the residual amorphous carbon in the heat-affected zone while achieving removal of the desired volume of the bone material at a rapid rate. Minimal thermal effects were predicted through computational simulation and were validated with the experimental outcome. In addition, this work reveals the in situ formation of a scaffold-like structure in the laser-machined region which can be conducive during healing.

Integrated experimental and computational approach to laser machining of structural bone.

This study describes the fundamentals of laser-bone interaction during bone machining through an integrated experimental-computational approach. Two groups of laser machining parameters identified the effects of process thermodynamics and kinetics on machining attributes at micro to macro. A continuous wave Yb-fiber Nd:YAG laser (wavelength 1070 nm) with fluences in the range of 3.18 J/mm2-8.48 J/mm2 in combination of laser power (300 W-700 W) and machining speed (110 mm/s-250 mm/s) were considered for machining trials. The machining attributes were evaluated through scanning electron microscopy observations and compared with finite element based multiphysics-multicomponent computational model predicted values. For both groups of laser machining parameters, experimentally evaluated and computationally predicted depths and widths increased with increased laser energy input and computationally predicted widths remained higher than experimentally measured widths whereas computationally predicted depths were slightly higher than experimentally measured depths and reversed this trend for the laser fluence >6 J/mm2. While in both groups, the machining rate increased with increased laser fluence, experimentally derived machining rate remained lower than the computationally predicted values for the laser fluences lower than ∼4.75 J/mm2 for one group and ∼5.8 J/mm2 for other group and reversed in this trend thereafter. The integrated experimental-computational approach identified the physical processes affecting machining attributes.

Matrix-induced autologous chondrocyte implantation (MACI) for chondral defects in the patellofemoral joint.

PURPOSE: Both autologous chondrocyte implantation (ACI) and tibial tubercle transfer (TTT) have been used to treat chondral defects in the patellofemoral joint resulting in clinical improvement. Our study investigates the magnetic resonance imaging (MRI) appearance of the matrix-induced autologous chondrocyte implantation (MACI) graft at 5-year follow-up to determine if it provides a durable treatment option in patients with an average age of 42 (standard deviation 11.6). METHODS: Twenty-three patients were available for follow-up. Nine patients required realignment of the extensor mechanism with lateral release and TTT. The MRI magnetic resonance observation of cartilage repair tissue (MOCART) scoring system was used to assess the graft status. Clinical outcomes were assessed at these time periods. RESULTS: The mean weighted MOCART composite score improved from 2.87 at 3 months to 3.39 at 5 years, indicating an intact appearance in most grafts. Graft height measured >50% of the adjacent native cartilage in 82% of patients. Clinical improvement assessed by the Knee Injury and Osteoarthritis Outcome Score, SF-36 (PCS) and the 6-minute walk test was demonstrated between pre-operative scores and final 5-year follow-up. 91% of patients would undergo MACI again. Correlation between MOCART and clinical scores were low in MACI to the patellofemoral joint. No significant difference was found in outcome between those that required realignment surgery compared with those that did not. CONCLUSION: Patellofemoral MACI provides a durable graft on MRI assessment at 5 years with resultant clinical improvement. Further work is needed to determine which defect locations may benefit most from this procedure. LEVEL OF EVIDENCE: IV.

"Epic Ear Defence"-A Game to Educate Children on the Risks of Noise-Related Hearing Loss.

Hearing loss resulting from overexposure to entertainment-related sounds is a modern concern. "Epic Ear Defence" places the player in the three-dimensional environment of the ear canal and challenges the player to defend the ear from various noises, to delay the onset of noise-related hearing loss.

Clinical and magnetic resonance imaging-based outcomes to 5 years after matrix-induced autologous chondrocyte implantation to address articular cartilage defects in the knee.

BACKGROUND: The availability remains limited of midterm clinical and radiologic results into matrix-induced autologous chondrocyte implantation (MACI). Outcomes are required to validate the efficacy of MACI as a suitable surgical treatment option for articular cartilage defects in the knee. HYPOTHESIS: A significant improvement in clinical and magnetic resonance imaging-based (MRI-based) outcomes after MACI will exist throughout the postoperative timeline to 5 years after surgery. Furthermore, patient demographics, cartilage defect parameters, and injury/surgery history will be associated with patient and graft outcome, whereas a significant correlation will exist between clinical and MRI-based outcomes at 5 years after surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A prospective evaluation was undertaken to assess clinical and MRI-based outcomes to 5 years in 41 patients (53 grafts) after MACI to the knee. After MACI surgery and a 12-week structured rehabilitation program, patients underwent clinical assessments (Knee injury and Osteoarthritis Outcome Score, SF-36, 6-minute walk test, knee range of motion) and MRI assessments at 3, 12, and 24 months, as well as 5 years after surgery. The MRI evaluation assessed 8 previously defined pertinent parameters of graft repair, as well as a combined MRI composite score. RESULTS: A significant improvement (P < .05) was demonstrated for all Knee injury and Osteoarthritis Outcome Score and SF-36 subscales over the postoperative timeline, as well as the 6-minute walk test and active knee extension. A significant improvement (P < .0001) was observed for the MRI composite score, as well as several individual graft scoring parameters. At 5 years after surgery, 67% of MACI grafts demonstrated complete infill, whereas 89% demonstrated good to excellent filling of the chondral defect. Patient demographics, cartilage defect parameters, and injury/surgery history demonstrated no significant pertinent correlations with clinical or MRI-based outcomes at 5 years, and no significant correlations existed between clinical and MRI-based outcome measures. At 5 years after surgery, 98% of patients were satisfied with the ability of MACI surgery to relieve knee pain; 86%, with improvement in their ability to perform normal daily tasks; and 73%, with their ability to participate in sport 5 years after MACI. CONCLUSION: These results suggest that MACI provides a suitable midterm treatment option for articular cartilage defects in the knee. Long-term follow-up is essential to confirm whether the repair tissue has the durability required to maintain long-term patient quality of life.

Radiological Assessment of Accelerated versus Traditional Approaches to Postoperative Rehabilitation following Matrix-Induced Autologous Chondrocyte Implantation.

OBJECTIVE: To assess the safety and efficacy of accelerated compared with traditional postoperative weightbearing (WB) rehabilitation following matrix-induced autologous chondrocyte implantation (MACI) of the knee, using MRI. METHODS: A randomized controlled study design was used to assess MRI-based outcomes of MACI grafts in 70 patients (45 men, 25 women) who underwent MACI to the medial or lateral femoral condyle, in combination with either traditional or accelerated approaches to postoperative WB rehabilitation. High-resolution MRI was undertaken and assessed 8 previously defined pertinent parameters of graft repair, as well as a combined MRI composite score at 3, 12, and 24 months postsurgery. The association between clinical and MRI-based outcomes, patient demographics, chondral defect parameters, and injury/surgery history was investigated. RESULTS: Both groups significantly improved (P < 0.05) in the MRI composite score and pertinent descriptors of graft repair throughout the postoperative period until 24 months postsurgery. There were no differences (P > 0.05) observed between the 2 groups. Patient age, body mass index, chondral defect size, and duration of preoperative symptoms were significantly correlated (P < 0.05) with several MRI-based outcomes at 24 months, whereas there were no significant pertinent correlations (P > 0.05) observed between clinical and MRI-based outcomes. CONCLUSION: The accelerated WB approach was not detrimental to graft development at any stage throughout the postoperative assessment timeline from baseline to 24 months postsurgery and may potentially accelerate patient return to normal function, while reducing postoperative muscle loss, intra-articular adhesions, and associated gait abnormalities.

A Prospective, Randomized Comparison of Traditional and Accelerated Approaches to Postoperative Rehabilitation following Autologous Chondrocyte Implantation: 2-Year Clinical Outcomes.

OBJECTIVE: To determine the safety and efficacy of "accelerated" postoperative load-bearing rehabilitation following matrix-induced autologous chondrocyte implantation (MACI). DESIGN: A randomized controlled study design was used to investigate clinical outcomes in 70 patients following MACI, in conjunction with either accelerated or traditional approaches to postoperative weight-bearing (WB) rehabilitation. Both interventions sought to protect the implant for an initial period and then incrementally increase WB. Under the accelerated protocol, patients reached full WB at 8 weeks postsurgery, compared to 11 weeks for the traditional group. Clinical outcomes were assessed presurgery and at 3, 6, 12, and 24 months postsurgery. RESULTS: A significant effect (P < 0.017) for time existed for all clinical measures, demonstrating improvement up to 24 months in both groups. A significant interaction effect (P < 0.017) existed for pain severity and the 6-minute walk test, with accelerated group patients reporting significantly less severe pain and demonstrating superior 6-minute walk distance over the period. Although there was a significant group effect (P < 0.017) for maximal active knee extension range in favor of the accelerated regime, no further significant differences existed. There was no incidence of graft delamination up to 24 months that resulted directly from the 3-month postoperative rehabilitation program. CONCLUSION: The accelerated load-bearing approach that reduced the length of time spent ambulating on crutches produced comparable if not superior clinical outcomes up to 24 months postsurgery in the accelerated rehabilitation group, without compromising graft integrity. This accelerated regime is safe and effective and demonstrates a faster return to normal function postsurgery.

Distribution of cerebral atherosclerosis by geographic location, race, and sex

The cerebral arteries (common carotid, internal carotid, vertebral, middle cerebral, and basilar arteries) were examined from 1547 autopsied persons in five countries (Norway, Guatemala, United States, Jamaica, and Chile). Subgroups comparisons were made using a basal group of cases from which were excluded all persons with coronary heart disease, peripheral arterial disease, other atherosclerotic complication, hypertension, and diabetes. The prevalence and mean extent of atherosclerotic lesions increase in each succeeding age group. Lesions appear to develop later in life in the cerebral arteries than in the aorta and the cerebral arteries than in the aorta and the coronary arteries. Men have more raised atherosclerotic lesions than women. The mean extent of fatty streaks in the cartoid arteries does not differ among age groups from 35 to 69 years of age, nor does it differ among location-race groups. The mean extent of raised atherosclerotic lesions in the carotid arteries increases in each succeeding age group after 35 years of age, and differs among location-race groups.The pattern of development of atherosclerosis in the carotid arteries follows that of the aorta. Fatty streaks appear in the intracranial and vertebral arteries much later in life than they do in the carotid arteries.The mean extent of both fatty streaks and raised lesions increases in each succeeding age group after 35 years of age, and the average involvement of both types of lesions differs among location-race groups. The pattern of development of atherosclerosis in the vertebral and intracranial arteries follows that of the coronary arteries. When location-race groups are ranked by extent of cerebral atherosclerosis, they rank in approximately the same order as when they are ranked by aortic and coronary atherosclerosis. (AU)

Histologic characteristics of coronary artery fatty streaks

The histologic characterictics of a standard site in the left interior descending coronary artery of 304 males between 10 and 39 years of age from seven different populations were examined. These seven location-race groups were ranked in the same order as the ranking based upon mean extent of raised atherosclerotic lesions in the coronary arteries and aorta to establish the tendency of each group to develop advanced atherosclerosis. Muscloelastic intimal thickening in the earlier decades does not predict the likelihood to develop severe atherosclerosis. Amount of intimal lipid and degree of cellular infiltration do predict the disposition to develop severe atherosclerosis later in life. Therefore, increased intimal lipid and cellular infiltration characterize coronary artery fatty streaks that are associated with their conversion to fibrous plaques. Necrosis of lipid-containing cells may release intracellular lipid into the extracellular space and thereby incite cellular infiltration and sequelae. (AU)

Clinical and pathological observations on Jamaican neuropathy: a report on 206 cases

The clinical features of 206 cases of a neuropathic syndrome in Jamaica are presented. The dominant feature is a spastic paraplegia. Approximately half of the cases have evidence of associated posterior column damage. In a minority optic atrophy, nerve deafness of selective anterior horn cell damage is found. The patients have been divided arbitrarily into two categories: 25 cases presenting predominantly with sensory ataxia, and in whom there is a high incidence of optic atrophy and eighth nerve deafness, with slight evidence of pyramidal tract damage. This group has a background of poor nutrition. (b) 181 cases presenting predominantly as a spastic myelopathy, and with a relative low incidence of optic atrophy and eight nerve deafness. The findings in ten necropsies from the spastic group are presented with their cases record. The histopathology is that of a chronic meningo-myelitis, with damage to the long tracts as the major lesion. Involvement of the brain, they grey matter of the cord and spinal nerve roots occurs to a lesser extent. An eleventh case is described with similar pathology, which clinically was thought to be an example of neurosyphilis. The relationship of this syndrome to other neuropathies is considered. The aetiology is discussed, with special reference to the possible role of syphilis and yaws in the spastic group. The majority of these cases have positive treponemal tests in the blood, but only 6 per cent have positive tests in the spinal fluid. The pathology has much in common with that of neurosyphilis, but lacks some of the features generally accepted as typical. The incidence is extremely high relative to other known forms of neurosyphilis in Jamaica. Other factors such as ingested toxins and vitamin deficiences may add to, or modify, the metabolic impairment. It is possible to envisage a spectrum of disease varying from a picture of non-inflammatory long tract degeneration to the active meningo-vascular reaction of florid adhesive arachnoiditis-a spectrum in which common causal factors could operate with variable degrees of intensity. This study emphasizes that our understanding of the pathogenesis and pathology of neurosyphilis in its many forms is far from complete (AU)

A comparitive study of coronary atherosclerosis

There are marked diferences in the incidence of ischaemic (atherosclerotic) heart disease (I H D) between various populations, and between groups within the same population. This is usually attributed to differences in the extent and severity of atherosclerotic lesions in the coronary arteries of these populations and groups. There is evidence that these differences became apparent relatively early in life. In association with the International Artherosclerosis Project a pilot study of the histology of coronary atherosclerosis in different races has been done. Cases from high, intermediate and low risk (of I H D) groups were selected in the age bracket 10-39 years and a qualitative and quantitative histological assessment of the coronary arteries made. The results suggested that the incidence and severity of certain lesions in the coronary arteries paralleled the predictable incidence of I H D in later life in the groups (AU)

Some factors influencing the development of atherosclerosis: A survey in Jamaica, West Indies

Using a quantitative method of assay the degree of atherosclerosis of the aorta, coronary arteries and cerebral arteries has been determined in a large, predominantly Negro, autopsy series in Jamaica, West Indies. There is a progressive worsening of the disease with age but there are considerable individual variations at all ages. The aorta, coronary and cerebral arteries are affected in that order in time and severity. Atherosclerosis is generally more severe in men and hypertension accentuates the disease, especially in women after the menopause. Hypertension is more important than atherosclerosis in causing cerebrovascular disease in Jamaica. Diabetes alone does not seem to influence adversely the development of atherosclerosis except in combination with hypertension. Evidence for the effect of malignant disease was inconclusive. Severe degrees of atherosclerosis are encountered in the Jamaican Negro but the supposed complications are relatively uncommon. This supports the view that factors other than initial disease, principally those connected with thrombosis, are concerned in the pathogenesis of ischaemic vascular disease. (AU)

Some further observations on atherosclerosis in Jamaica (abstract only)

Preliminary studies in Jamaica indicated that the incidence of athero-sclerosis of the aorta showed a similar pattern to that in the United States although the incidence of myocardial infarction, a presumed complication of atherosclerosis, is far lower in Jamaica than in the U.S.A. The study has been extended to include a comparative assay of the coronary arteries and it has been found that the degree of coronary atherosclerosis is significantly greater in comparable age groups in the United States of America than in Jamaica. The implications of this dissociation are discussed. The Jamaican results have been analysed to determine the influence of age, sex, hypertension and diabetes on the disease process (AU)

Geographic differences in the severity of aortic and coronary atherosclerosis

Comparison of aortic and coronary atherosclerosis in the United States, Jamaica, Japan and India demonstrates that after the first two decades of life, there is a greater severity of intimal alteration in the United States than in the other population groups. The 3 foreign populations exhibited much less coronary atherosclerosis and a lower incidence of myocardial infarction. Their diets, too, were of lower caloric content and contained less than half the fat found in the United States diet. In Japan and Jamaica, atherosclerosis proved to be disproportionately more severe in the aorta than in the coronary arteries. Accordingly, appraisals of atherosclerosis limited to the aorta do no provide adequate indexes of geographical variations. A much lower proportion of complicated atheromatous lesions (ulcerated or calcified plaques) accounted for most of the differences observed. While there was a general parallelism between the severity of coronary atherosclerosis and the frequency of myocardial infarction, there were instances of cardiac infarction associated with relatively minor degrees of coronary intimal alteration. These situations indicate that virtually all grossly recognizable intimal lesions may be complicated by thrombosis (Summary)

Primary plasmocytoma of the stomach

The seventh case of solitary plasmocytoma of the stomach is reported. It is suggested that in this case and possibly in others the tumor arose as a rare type of malignant change in a chronic peptic ulcer. The literature on extramedullary plasmocytoma of the gastro-intestinal tract is reviewed (Summary)

Atherosclerosis and ischaemic heart-disease: observations in Jamaica

Using a standardised technique, the incidence of atherosclerosis of the aorta at 500 necropsies in Jamaica has been compared with the incidence in published series in which the same method was employed. The predominantly Negro population in Jamaica develops a degree of aortic atherosclerosis similar to that of a mixed population in New Orleans, U.S.A. The incidence of myocardial infarction, however, is much lower in the Jamaican series. Other thrombotic diseases are also rarer in Jamaica. Since there is no constant relation between the incidence of atherosclerosis and the incidence of coronary thrombosis, they are very unlikely to have the same cause. Atherosclerosis may or may not be promoted by a dietetic factor; but, if it is, the same factor can hardly be responsible for the thrombosis which results in ischaemic heart-disease. In aetiological studies the two conditions need to be clearly distinguished. Since advanced atherosclerosis is compatible with health and long life, investigation of the cause of thrombosis is of more immediate concern (AU)

A study of the vessels of the placental bed in normotensive and hypertensive women

Biopsies of the placental bed have been taken from 36 patients. Histological examination has been carried out with particular reference to pathological changes in the maternal vessels and these changes have been related to the clinical histories of the patients. Vascular lesions have been found in material obtained from hypertensive and from toxaemic women. These changes are in no way distinguishable from those generally acknowledged to occur as a result of systemic hypertension. They are directly related in extent to the clinical severity of the disease. No such changes have been found in normal patients. Apart from differences of degree, the vessel changes in essential hypertension and pre-eclampsia appear identical. They are thought to be due to hypertension (AU)

The placental bed vessels in normotensive and hypertensive pregnancy (abstract only)

During Caesarean section biopsies of the placental bed have been taken from normotensive and hypertensive women. Historical examination has been especially directed at the maternal vessels and any changes found related to the clinical histories of the patients. Changes have been found in the maternal vessels of women suffering from essential hypertension and pre-eclampsia. They do not differ from one another except in degree and are indistinguishable from those changes known to occur in association with systemic hypertension. They have not been found in normotensive patients. It is felt that the hypertension and the accompanying vasular lesions may be responsible for the reduction of the maternal placental blood flow found to occur in patients with pre-eclampsia and essential hypertension. (AU)