Experimental production of extra- and intra-articular fractures of the os calcis

Although studies have been conducted in the past to duplicate traumatic fra ctures of the os calcis, biomechanical force data as a function of extra- a nd intra-articular fractures are not available. Consequently, in this study , a dynamic single impact model was used to provide such information. Using intact human cadaver lower extremities, impact loading was applied to the plantar surface of the foot using a mini-sled pendulum equipment. The proxi mal tibia was fixed in polymethylmethacrylate. Following impact, pathology to the os calcis was classified into intact (no injury; 14 cases), and extr a-articular (6 cases) and intra-articular (6 cases) fractures. Peak dynamic forces were used to conduct statistical analysis, Mean forces for the inta ct and (both) fracture groups were 4144 N (standard error, SE: 689) and 780 2 N (SE: 597). Mean forces for the extra- and intra-articular fracture grou ps were 7445 N (SE: 711) and 8159 N (SE: 1006). The peak force influenced i njury outcome (ANOVA, p < 0.005). Differences in the forces were found betw een intact and injured specimens (p < 0.01); intact specimens and specimens with extra-articular pathology (p < 0.001); intact specimens and specimens with intra-articular pathology (p < 0.005). The present experimental proto col, which successfully reproduced clinically relevant os calcis pathology, can be extended to accommodate other variables such as the simulation of A chilles tendon force, the inclusion of other angles of Force application, a cid the application of the impact force to limited regions of the plantar f orce of the fool in order to study other injury mechanisms. Published by El sevier Science Ltd.