Biomechanical characteristics of fracture of humeral ectocondyle

Limin YU; Riqi CHEN; Zugen ZHENG

ABSTRACT

BACKGROUND:

Fracture of humeral ectocondyle is a kind of articular epiphyseal fracture. It is one of the most prevalent disorder of cubital articulation. The occurrence of fracture and the mechanical mechanism of treatment is not very well cognized in clinic.

OBJECTIVE:

To analyze the stress distribution of the humeral ectocondyle in different postures so as to investigate the treatment mechanism of the humeral ectocondyle fracture.

DESIGN:

Computer simulation study on stress.

SETTING:

Department of Experimental Mechanics, Fuzhou University, and Department of Orthopedics, Third Affiliated Hospital of Peking University.MATERIALS This experiment was conducted in the Fujian Experimental Mechanic Committee of Fuzhou University between January 2000 and December 2002. Humerus from a 6-year-old. corpse (Provided by the Department of Anatomy of Fujian College of Traditional Chinese Medicine). Instruments were computer, SUPER-SAP93 software, material sickle and measuring instrument and so on.

METHODS:

9 kinds of loading conditions were simulated and added on three dimensional finite elemental model of humerus in SUPER-SAP93software, and then the stress distribution was filed out and analyzed.MAIN OUTCOME

MEASURES:

The average Mises stress of lateral condylar area and humeral trochlea area.

RESULTS:

At flection posture of elbow, the average Mises stress of lateral condylar area was the largest while at extension posture the stresses of nodes affected by extensor tendon were larger than those of lateral condyle.

CONCLUSION:

At the flection posture of elbow, the fracture of lateral condyle of humerus was resulted from c9llision occurring when radius and ulna struck humerus while at extension posture, it was chiefly due to extensor tractive force. We can use extensor tractive force to reduce the fracture of lateral condyle and avoid extensor tractive force to fix it.