Morphometric analysis of lister's tubercle and its consequences on volar plate fixation of distal radius fractures.

PURPOSE: The objective of this study was to measure the size and shape of Lister's tubercle and the depth of the extensor pollicis longus (EPL) groove to assess the risk of injury to the EPL tendon when performing volar plating of distal radius fractures. METHODS: The length and height of Lister's tubercle and the depth of the EPL groove were measured in 100 cadavers. RESULTS: The size of Lister's tubercle varied from 2 to 6 mm (average, 3.6 mm) in height radial to the tubercle and from 6 to 26 mm (average, 18.3 mm) in length. The depth of the EPL groove varied from 1 to 5 mm (average, 2.8 mm), with 63% being greater than 2 mm in depth. The height between the depth of the groove and the tip of the tubercle varied between 4 and 10 mm (average, 7.1 mm). No correlation was found with gender or right-side or left-side specimens. CONCLUSIONS: The individual and combined height of Lister's tubercle and the depth of the EPL groove are considerable. This fact needs to be considered when performing volar plating of distal radius fractures because of the possibility that it might be difficult to determine precisely the presence and amount of past-pointing of the distal screws.

Various circular arc radii of the distal volar radius and the implications on volar plate osteosynthesis.

The purpose of this anatomical study was to explore the different circular arc radii of the distal volar radius and provide more detailed anatomic information that will further the understanding of volar plate osteosynthesis. The profiles of the volar distal radii of 100 cadaver specimens were measured with a common profile gauge. Profiles were copied onto paper and then matched to a best-fit circular arc template to determine the radius of curvature on the radial and ulnar sides of the distal volar radius. The mean circular arc radius of the distal volar surface was 2.6 cm (+/-1 cm, 1-6 cm) on the radial side and 2.3 cm (+/-1 cm, 1-6 cm) on the ulnar side. A significant difference (P<.01) was noted in the radii of curvature of the distal radius in 55% of the study population. In 37% of these cases, the circular arc radius flattens toward the ulnar side. In 63%, it flattens toward the radial side. This characteristic may lead to a false rotation position of the distal fracture fragment following volar plate osteosynthesis. In addition, suboptimal or incorrect plate position may result due to the discrepancy between the plate radius of curvature and the radius of curvature of either the radial or ulnar volar radius.

The pyramidal lobe: clinical anatomy and its importance in thyroid surgery.

The pyramidal lobe could be a source of pitfalls in thyroidectomy, due to its frequency but unreliable preoperative diagnosis on scintigraphic images. Special attention has to be paid to the pyramidal lobe to avoid leavings of residual tissue when complete removal of the thyroid is indicated. Sixty cadaveric specimens were examined with special emphasis to the topographical anatomy and expansion of the pyramidal lobe. A pyramidal lobe was found to be present in 55% of the cadavers (32/58). It was found more frequently in men than in women. In men the median length was 14 mm and in women 29 mm. An accessory thyroid gland was present in one specimen, in four cases the isthmus was missing. The pyramidal lobe branched off more frequently from the left part of the isthmus (16) than from the right (7) or the midline (9). In two cases it originated from the left lobe. Additionally 23 scintigraphic images were analyzed to evaluate the visualization of a pyramidal lobe. Only three of them showed enlargements of the isthmus that could be taken as a pyramidal lobe. Due to its frequency the pyramidal lobe should be regarded as a normal component of the thyroid. It is not reliably diagnosed by scintigraphic imaging because scintigraphy can only give functional information but not morphological one. Therefore the anterior cervical region has to be investigated very carefully during operation in order not to leave residual thyroid tissue in total thyroidectomy.