Does lesion size affect the outcome in avascular necrosis?

The size of the necrotic lesion may be a significant factor in predicting outcome and determining treatment in hips with avascular necrosis. However, to date most reports on the treatment of this condition have not attempted to correlate outcome with lesion size. Seventy-three hips with avascular necrosis were evaluated, 11 in Stage I and 62 in Stage II. All were treated with core decompression and bone grafting. Patients were followed up 2 to 6 years (mean, 39 months). The results were determined by change in Harris hip score, degree of radiographic progression, and the need for total hip replacement. Outcome was correlated with the lesion size, stage, etiology, and other factors. In Stage I, the true three-dimensional size of the lesion was measured with a new technique of quantitative magnetic resonance imaging. In Stage II, measurements were obtained from radiographs using a modular system for quantitative digital analysis. Hips were divided into three groups based on lesion size: Group A, less than 15% of femoral head involvement; Group B, 15% to 30%; and Group C, greater than 30%. There were no significant differences in outcome between Stages I and II and no relationship to etiology or other demographic factors. When correlated with lesion size, radiographs on a 21-point scale showed progression by 1.1, 4.2, and 4.3 points; the Harris hip score showed an improvement of 10.6 and 3.3 points and a loss of 3.6 points; and total hip replacement was required in 7%, 31%, and 33% of Group A, B, and C lesions, respectively. The difference in outcome between small lesions and large or medium lesions was statistically significant, but no significant differences were seen between medium and large lesions. These observations emphasize the importance of lesion size in predicting outcome after core decompression and grafting and possibly after other surgical and nonsurgical methods of managing hips with avascular necrosis. They also encourage the use of methods of evaluation and staging that include a determination of lesion size and stage.     

Histological assessment of colorectal adenomas by size. Are polyps less than 10 mm in size clinically important?

OBJECTIVE: To define the relative risk of malignant transformation in colorectal adenomas less than 10 mm in diameter. DESIGN: Prospective study. SETTING: District general hospital, UK. SUBJECTS AND MATERIALS: 1228 polyps detected endoscopically in 445 patients over the 10-year period 1989-1999. MAIN OUTCOME MEASURES: Site, size, histological type and dysplastic grade of polyp. RESULTS: 657 of the 1228 polyps were adenomas: 281 (43%) tubular, 339 (51%) tubulovillous and 37 (6%) villous. In the 357 adenomas less than 10 mm in diameter, 11 (3%) were severely dysplastic and 2 carcinomas were detected, though neither was less than 5 mm in size. The relative risk of malignancy or severe dysplasia in adenomas of 10 mm or more compared with those of less than 10 mm was 3.8 (p < 0.0001). CONCLUSIONS: Although severe dysplasia and malignancy do occur in adenomas less than 10 mm in size, they are rare in lesions of less than 5 mm. We recommend routine destruction of all polyps 5 mm or more in size, though it is not essential to remove those of less than 5 mm if they are kept under surveillance.     

Increased infarct size in uremic rats: reduced ischemia tolerance?

In patients with renal failure, myocardial infarction (MI) is more frequent and the rate of death from acute MI is very high. It has been argued that ischemia tolerance of the heart is reduced in uremia, but direct evidence for this hypothesis has not been provided. It was the purpose of this study (1) to ligate the left coronary artery and to measure the nonperfused area (risk area: total infarction plus penumbra) as well as the area of total infarction in subtotally nephrectomized (SNX) rats compared with sham-operated pair-fed control rats and (2) to examine the effects of potential confounders such as BP, sympathetic overactivity, and salt retention. The left coronary artery was ligated for 60 min, followed by reperfusion for 90 min. For visualizing perfused myocardium, lissamine green ink was injected. The nonperfused area (lissamine exclusion) and the area of total infarction (triphenyltetrazolium chloride stain) were assessed in sections of the left ventricle using image analysis. Groups of SNX rats also received: antihypertensive treatment (nadolol plus hydralazine); moxonidine; high salt diet or low salt diet (1.58% versus 0.015%). In surviving animals, the nonperfused area at risk (as the proportion of total left ventricular area), presumably determined by the geometry of vascular supply, was similar in sham-operated and SNX animals (0.38 +/- 0.13 versus 0.45 +/- 0.09; NS). In contrast, the infarcted area, given as a proportion of the nonperfused risk area, was significantly (P < 0.003) higher in SNX (0.68 +/- 0.09) compared with sham-operated (0.51 +/- 0.11) rats and was not altered by any of the above interventions. The finding that a greater proportion of nonperfused myocardium undergoes total necrosis is consistent with the hypothesis of reduced ischemia tolerance of the heart in renal failure. The findings could explain the high rate of death from MI in patients with impaired renal function.     

Sample size calculations in surgery: are they done correctly?

BACKGROUND: Randomized controlled trials (RCTs) are considered the gold standard for evidence-based clinical research, but prior work has suggested that there may be poor reporting of sample sizes in the surgical literature. Sample size calculations are essential for planning a study to minimize both type I and type II errors. We hypothesized that sample size calculations may not be performed consistently in surgery studies and, therefore, many studies may be "underpowered." To address this issue, we reviewed RCTs published in the surgical literature to determine how often sample size calculations were reported and to analyze each study's ability to detect varying degrees of differences in outcomes. METHODS: A comprehensive MEDLINE search identified RCTs published in Annals of Surgery, Archives of Surgery, and Surgery between 1999 and 2002. Each study was evaluated by two independent reviewers. Sample size calculations were performed to determine whether they had 80% power to detect differences between treatment groups of 50% (large) and 20% (small), with one-sided test, alpha = 0.05. For the underpowered studies, the degree to which sample size would need to be increased was determined. RESULTS: One hundred twenty-seven RCT articles were identified; of these, 48 (38%) reported sample size calculations. Eighty-six (68%) studies reported positive treatment effect, whereas 41 (32%) found negative results. Sixty-three (50%) of the studies were appropriately powered to detect a 50% effect change, whereas 24 (19%) had the power to detect a 20% difference. Of the studies that were underpowered, more than half needed to increase sample size by more than 10-fold. CONCLUSIONS: The reporting of sample size calculations was not provided in more than 60% of recently published surgical RCTs. Moreover, only half of studies had sample sizes appropriate to detect large differences between treatment groups.     

Ureteral length in live donor kidney transplantation; Does size matter?

The aim of this study was to evaluate the role of ureteral length on urological complications. Data were retrospective collected from the INEX‐trial database, a RCT to compare the intravesical to the extravesical ureteroneocystostomy. Ureteral length was measured in 198 recipients and used to divide recipients into three categories based on interquartile ranges: short (≤8.5 cm), medium (8.6–10.9 cm) and long ureters (≥11 cm). Urological complications were defined as the number of percutaneous nephrostomy placements (PCN). Fifty recipients fell into the short, 98 into the medium and 50 recipients into the long ureter category. Median follow‐up was 26 (range 2–45) months. There was no significant difference in number of PCN placements between the categories. There were 9 (18%) PCN placements in the short ureter category, 21 (20%) in medium ureter category and 10 (21%) in the long ureter category, P = 0.886. Risk factor analysis for gender, arterial multiplicity and type of ureteroneocystostomy showed no differences in PCN placements between the three ureteral length categories. We conclude that ureteral length alone does not seem to influence the number of urological complications.     

Is kidney size a useful predictor of renal function in the elderly?

Despite its widespread use, the diagnostic yield of ultrasonography to detect early stages of reduced renal function in the elderly remains doubtful. METHOD: Sixty-two patients (age: 74.8 +/- 6.7 years, 30 females) attending a geriatric ward were examined. Non-insulin-dependent diabetes was present in 28 patients and 32 were hypertensive. Exclusion criteria were previously known renal failure, an elevated serum creatinine above 2 mg/dl at admission or apparent cognitive impairment. Inulin clearance (C(IN)), Cockcroft estimation and urinary albumin excretion rate (UAER) were determined. Renal parenchymal volume, renal volume and mean renal length were calculated using data obtained by ultrasonography. RESULTS: A multiple regression analysis identified C(IN) as the main determining factor on renal parenchymal volume (beta = 0.360; p = 0.004). Body height showed additional influence (beta = 0.295; p = 0.018), but age, gender, diabetes, UAER and hypertension did not. Cockcroft estimation, ultrasonographic markers of renal size and further confounding variables were evaluated in a subsequent multiple regression analysis. Cockcroft estimation explained the major part of the variance (beta = 0.783; p < 0.001) and the occurrence of diabetes showed a borderline additional effect. But there was no supplementary influence of any ultrasonographic parameter. In 11 patients, C(IN) was reduced to < or = 60 ml/min. ROC analysis revealed poor diagnostic efficacy of all ultrasonographic parameters (AUC < 0.7336) compared to Cockcroft estimation (AUC = 0.8718). CONCLUSION: Although a linear relation between C(IN) and renal parenchymal volume could be shown, ultrasonography cannot replace or complement Cockcroft estimation in order to detect early reduced renal function in the elderly. Nevertheless, reduced renal parenchymal volume may occur prior to elevation of serum creatinine in the elderly and should be noted carefully on routine ultrasonographic examinations.     

Increase in size of the pulmonary autograft after the Ross operation in children: growth or dilation?

OBJECTIVE: We sought to assess growth properties of the pulmonary autograft after the Ross operation in children. METHODS: Eight infants with critical aortic stenosis who underwent the Ross operation early in life (median age, 6.4 months) were followed up regarding the possible growth of the autograft. The pulmonary autograft was measured repeatedly by echocardiography during the follow-up, ranging from 6 months to 7 years (median, 5.2 years). Twelve normal children who served as control subjects were similarly followed from 3.9 to 5.8 years (median, 4.9 years). RESULTS: Somatic growth during the follow-up period was significant and was reflected in a doubling of the body surface area, which increased from 0.33 +/- 0.14 m(2) to 0.74 +/- 0.21 m(2). The proximal part of the autograft increased from 13.6 +/- 3.6 mm to 23.3 +/- 3.7 mm (mean +/- SD) and the distal part from 10.5 +/- 2.5 mm to 15.9 +/- 2.8 mm. Growth pattern of the autograft was analyzed by relating measured diameters to predicted normal diameters (ie, Z values). During the first year after the operation, the mean Z value of the proximal autograft increased from 0.2 to 2.2, indicating a more rapid increase than the predicted increase and was also significantly higher than that of the control group (P =.01). After the first year, Z-value changes in patients and control subjects were very similar. CONCLUSIONS: We thus conclude that the pulmonary autograft in the aortic position after the Ross operation does increase in size and that the pattern of this increase is suggestive of passive dilation in the early postoperative period, followed by normal active growth.     

The CobraPLA in 110 anaesthetized and paralysed patients: what size to choose?

Editor—The Cobra Perilaryngeal Airway (PLA)^TM is a newsupraglottic device,¹ which consists of a tube with an inflatablecuff and a 15 mm standard adaptor. The softened distal end (CobraPLA^TMhead) of the breathing channel is designed to be positionedin the hypopharynx, opposite the laryngeal inlet, to divertthe inspiratory gas into the trachea through the slotted openings(Fig. 1). View larger version (75K): [in this window] [in a new window]   Fig 1 The CobraPLA^TM.   Ethics committee approval and written informed consent was obtainedfrom the patients before     

Does body size account for gender differences in femur bone density and geometry?

The extent to which greater bone strength in men is caused by proportionately greater bone mass versus bigger bone size is not clear, primarily because the larger overall body size of men has made direct comparisons of skeletal measures difficult. We examined gender differences in femur neck (FN) areal bone mineral density (BMD) values collected from 5,623 non-Hispanic whites aged 20+ years in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) before and after correction for measured height and weight. We supplemented the conventional areal BMD data (Hologic QDR 1000) with measurements of areal BMD and geometric properties (subperiosteal width, section modulus, and cortical thickness) made at narrow "cross-sectional" regions traversing the FN and the proximal shaft using a structural analysis program. Before body size adjustment, men had significantly higher values than women for all variables at the three measurement sites (p < 0.0001). Adjustment for body size reduced the differences between the sexes for all variables but had a greater effect on BMD (1-8% higher in men) than on geometry (5-17% higher in men). When examined by age, the sex discrepancy was significantly greater in the older group for all variables except subperiosteal widths. We conclude that although body size difference may account for most of the areal BMD difference between men and women, male bones are still bigger in ways that suggest greater bone strength. These differences may contribute importantly to lower fracture risk in men.