Phil Blyth

A comparison of embalming fluids for use in surgical workshops.

There is a growing need to learn surgical skills without risk to patients. One of the major determining factors on the suitability of specimens for surgical workshops is the fluid used for embalming. This study sought to compare three different arterial embalming preparations to a single fresh cadaver. Eleven cadavers embalmed using Graz (single cadaver), Dodge (four cadavers) and Genelyn (five cadavers) preparations were compared using four criteria; joint flexibility measured with a goniometer, tissue pliability rated on standardized videos of instrument handling, tissue color analyzed on standardized photographs and resistance to fungal growth identified by inoculation and observation of tissue blocks. The cadaver embalmed according to the Graz method had joint flexibility comparable to fresh tissue while the Dodge and Genelyn cadavers were less flexible. Tissue pliability was significantly affected by the Dodge and Genelyn methods while the Graz method tissue remained most like fresh tissue. The Graz method cadaver had color that was most akin to fresh tissue and the Dodge method cadavers were relatively more like fresh than the Genelyn. The Dodge and Genelyn method had quite similar fungicidal properties (3/11 Dodge and 2/9 Genelyn embalmed cadavers susceptible) while the Graz method cadaver did not grow mould. Variation exists between cadavers; however, the Graz method produced a cadaver with more flexible joints, better tissue quality and muscle color closest to the fresh specimen. The Dodge and Genelyn methods are similar with the exception of tissue color where the Dodge method was more similar to fresh tissue. Clin. Anat. 24:155–161, 2011.

Screw placement after pinning of slipped capital femoral epiphysis: a postoperative CT scan study.

Background Unrecognized pin penetration in the treatment of slipped capital femoral epiphysis has serious long-term sequelae. The purpose of this study was to use postoperative computerized tomographic (CT) scans to determine the true position of the screw tip when compared with standard radiograph views. Methods Twenty-four patients with 33 slipped capital femoral epiphyses were included in the study. Intraoperative or postoperative radiographs [anteroposterior (AP) and frog lateral] were compared with postoperative CT scans (coronal and axial) to determine (1) distance of the screw tip from the subchondral bone of the femoral head, (2) the number of screw threads across the physis, and (3) the 3-dimensional placement of the screw tip in the femoral head. Results The positions of 38 screws in 33 hips were assessed. Screw position within specific quadrants of the femoral head was more anterior and superior than appreciated on radiographs. AP radiographs overestimated the distance between the screw tip and the subchondral bone, the average distance being 5.5 mm on AP radiographs and 3.4 mm on coronal CT (P<0.0001). Bland-Altman analysis confirmed 95% limits of agreement of −5.6 to 1.5 mm, indicating that screws could be up to 5.6 mm closer to the subchondral bone than estimated by the AP radiograph. Closer agreement was found between the frog lateral radiograph and the axial CT views, with the distance from the subchondral bone averaging 4.7 mm on frog lateral radiographs and 4.1 mm on axial CT (P<0.01). Bland-Altman analysis showed 95% limits of agreement between the 2 measures of −3.5 to 2.3 mm, suggesting that some screws were up to 3.5 mm closer to the subchondral bone. Three more anteriorly placed screws seemed to penetrate subchondral bone on CT, findings not shown on standard radiographs. Conclusions Frog lateral radiographs of the hip provide a more accurate estimation of screw placement than AP radiographs. Screws closer than 4 mm to the subchondral bone on frog lateral radiographs or 6 mm on AP radiographs may penetrate subchondral bone. Level of Evidence Diagnostic study, Level II.

Ancestry and BMI Influences on Facial Soft Tissue Depths for A Cohort of Chinese and Caucasoid Women in Dunedin, New Zealand

This study measured and assessed facial soft tissue depths (FSTDs) in adult female Chinese and New Zealand (NZ) Europeans (Caucasoids). Ultrasound was used to obtain depths at nine landmarks on 108 healthy subjects (51 Chinese, 57 NZ European), erect positioned, of same age group (18–29 years). Height and weight were also recorded. Statistical analysis focused on comparison of tissue depth between the two ancestry groups and the influence of Body Mass Index (BMI) (kg/m2). Results showed mean depth differences at Supra M2 and Infra M2 landmarks significantly greater for Chinese than Caucasoid women for all three BMI Classes (BMI <20, 20 ≤ BMI < 25, 25 ≤ BMI < 30), even BMI <20. For both groups BMI positively correlated with FSTD values at all landmarks except Labrale superius. This study enabled ancestry and BMI influence on FSTDs to be observed and compared for two distinct groups. Results add to knowledge about facial tissue depth variation.

Position Effect on Facial Soft Tissue Depths: A Sonographic Investigation

The head is positioned erect for an approximation; yet most facial soft tissue depths (FSTD) used are measured from supine subjects. Depth difference might be significant, but there is a paucity of data to verify. This study compared erect and supine values for 17 landmarks from 30 healthy New Zealand (European population affinity) women (18–30 or 40–55 years) in erect then supine positions. Height, weight, and sonographic FSTD data, totaling 1020 measurements, were obtained. Three midline and seven averaged bilateral values were compared using ANOVA, p values, and Pearsons correlations. Correlative strength of age and body mass index, BMI (kg/m2), was determined by values. Results showed averaged erect and supine differences were significant for four of ten FSTDs. Between individuals, difference was various and not unidirectional. In conclusion, depth differences were observed but not all significant or unidirectional, BMI significantly influenced nine FSTD values, but age group did not.