Anatomical study on 200 dry clavicles. Clinical relevance of the entity of the lateral and medial curve.

Many morphometiic studies have been carried out with the aim of studying anatomical characteristics of the clavicle which may predispose to joint or periarticular diseases, particularly those of the subacrornial space. However, no information has emerged regarding the morphometric features that may be predisposing to fractures of the clavicle. We have studied 200 dry clavicles obtained from 4 anatomical musei to analyze the ratio between the length ofthe clavicle and the sinuosity ofthe medial and lateral curves in order to determine whether a clavicle with a particular shape has more possibilities to undergo fractures when submitted to axial load. Material and methods. Measurements of the length of the clavicles (L) were performed by means of a caliper. The clavicles were then put on the plane of a photocopier respecting their anatomical posinon. Papers showing the true shapes of bones were obtained. Starting from the apex ofthe convex side ofthe medial come, we traced, on the papers. the tangent line to the most anterior part of the lateral end. Similarly we traced the line between the apex of of the convex side ofthe lateral curve and the most posterior part of the clavicle facet for the sternoclavicular joint. The two lines were measured and registered as ml and ll respectively. The longest perpendicular lines at the ml and ll were measured and registered as mh and lh, respectively. Succesively. the ratio: (ml / mh + ll / lh) was calculated. Statistical analysis was performed with use ofthe linear regression analysis- Results. The mean value of the ratio ml / mh was 6.25 (range; 4 7 a 9.8). while that of ll / hl was 7.05 (range 4.2-14.1). The extremes ofthe ratio (ml/mh +ll/lh) / L ranged from 0.71 to 1.49. However. in 81% of the clavicles the range was between 0.80 and 1.15. So close values indicate that the deepth of the two curves decreases with the increase in the length ofthe clavicle. No correlations emerged between the lateral and medial curves. Discussion. DePalma. in 1973, observed that the more sinuous the clavicle the more vertically oriented the lateral articular facet. He also thought that a vertically oriented facet could predispose to osteoarthritic changes of the acroinioclavicular joint. ln our speciments we did not llnd a higher prevalence of degenerative changes (spurs) in sinuons clavicles. However, we observed that the shorter the clavicle the deeper its medial and lateral curves. This correlation was statistically significant. Since, the lesser resistent a curved long bone to the axial loading the more pronounced its curvature, it is statistically more plausible that a subject with a short clavicle has more possibilities to undergo a fracture of the clavicle following a fall on the shoulder than a subiect with a longer clavicle.