Frequent misclassifications in nonhuman comparisons might reflect influences of habitual load complexity and/or strain-mode distributions, or other factors not accounted for by these two considerations.
Double (segmental) clavicle fractures, involving both the medial and lateral aspects of the clavicle, are very uncommon. Even less common is an asynchronous double fracture with one of the fractures being a nonunion. We report the case of a 30-year-old healthy male patient who had an unusual double clavicle fracture (medial nonunion, lateral acute) that occurred in separate traumatic events during motocross (motorcycle) racing. His fractures were treated surgically in two stages. In the first stage a long reconstruction plate was used that spanned onto the sternum and two transcortical screws were placed into the manubrium to enhance purchase for the deficient bone of the medial clavicle. In accordance with the preoperative plan, the medial one-third of the plate and the medial four screws (of the total 13 used) were removed. Although our patient had an excellent final result, he did have an intraoperative pneumothorax that was treated uneventfully with a chest tube. Medial clavicle fractures are difficult to treat, especially if they are nonunions and surgical complication rates can be high. Our case is one of the few that has been described where temporary sternoclavicular plating was successful in achieving an excellent long-term outcome.
ObjectivesThis investigation sought to advance the work published in our prior biomechanical study (Journal of Orthopaedic Research, 2016). We specifically sought to determine whether there are additional easy-to-measure parameters on plain radiographs of the proximal humerus that correlate more strongly with ultimate fracture load, and whether a parameter resembling the Dorr strength/quality characterisation of proximal femurs can be applied to humeri.Materials and MethodsA total of 33 adult humeri were used from a previous study where we quantified bone mineral density of the proximal humerus using radiographs and dual-energy x-ray absorptiometry (DEXA), and regional mean cortical thickness and cortical index using radiographs. The bones were fractured in a simulated backwards fall with the humeral head loaded at 2 mm/second via a frustum angled at 30° from the long axis of the bone. Correlations were assessed with ultimate fracture load and these new parameters: cortical index expressed in areas (“areal cortical index”) of larger regions of the diaphysis; the canal-to-calcar ratio used analogous to its application in proximal femurs; and the recently described medial cortical ratio.ResultsThe three new parameters showed the following correlations with ultimate fracture load: areal cortical index (r = 0.56, p < 0.001); canal-to-calcar ratio (r = 0.38, p = 0.03); and medial cortical ratio (r = 0.49, p < 0.005). These correlations were weaker when compared with those that we previously reported: mean cortical thickness of the proximal diaphysis versus ultimate fracture load (r = 0.71; p < 0.001); and mean density in the central humeral head versus ultimate fracture load (r = 0.70; p < 0.001).ConclusionSimple-to-measure radiographic parameters of the proximal humerus reported previously are more useful in predicting ultimate fracture load than are areal cortical index, canal-to-calcar ratio, and medial cortical ratio.Cite this article: J. G. Skedros, C. S. Mears, W. Z. Burkhead. Ultimate fracture load of cadaver proximal humeri correlates more strongly with mean combined cortical thickness than with areal cortical index, DEXA density, or canal-to-calcar ratio. Bone Joint Res 2017;6:1–7. DOI: 10.1302/2046-3758.61.BJR-2016-0145.R1
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