| Objective 1. To measure 19 anatomical parameters of the proximal end of the radius(PEOTR) in order to provide reference gist for reasonable placement of internal fixation and improved design of prosthesis in treating radial proximal fractures. 2.To discuss the role of radial head on stability of elbow joint and the impact of resection of radial head on it in different circumstances by establishing the model of the fracture of the radial head(RH) accompanied with or not the injury of the ulnar collateral ligament (UCL) and carrying out Biomechanical Research on the elbow in cadaveric specimens.Methods sixty adult speciments of upper limb(15 men and 15 women) preserved with 4% formalin solution were dissected and radius and ulna removed from them were used for related measurement,such as the length of the PEOTR, the medial height of the articular circumference(AC), the lateral height of the AC, and so on. The anatomical parameters were compared between male and female. All datas were calculated by Stata 7.0 statistic software. Forty adult speciments of upper limb preserved with 4% formalin solution were dissected to establish four kinds of specimens with elbow joint and ligaments as follow:①intact (n=10) ;②excision of the RH (n= 10) ;③release of the UCL (n= 10) ;④excision of the RH together with release of the UCL (n=10).Under two-newton-meter valgus torque, and at 0, 30, 60, 90 and 120 degrees of flexion with the forearm in the precise angle-measuring instrument, the valgus elbow laxity was quantified: All analysis was performed with SPSS 13. 0 software to compare the valgus stability of the elbow between every group.Results 1. The parameters ,such as the length of the PEOTR, the medial height of the AC, the lateral height of the AC, the anterior height of the AC, the posterior height of the AC, the maximum depth of the fovea of radial head, the length of the lateral arc of PEOTR , the maximum vertical height of the lateral arc, the transverse diameter of the radial neck above radial tuberosity, the distance between the proximal end of radial head and the superior border of radial tuberosity, the distance between the proximal end of radial head and the middle of radial tuberosity, the transverse and sagittal diameter of radial head, the diameter of the fovea of radial head ,of men are larger than those of women(P<0.05), but the differences in the angle between the axis of the radial neck and diaphysis , the range of contact of radians and the range of non-contact of radian between the AC and the URC at the neutral position, the greatest range of pronation and supination of the foream, were not significant between men and women(P>0.05). 2. The least valgus laxity was seen in the intact state and its stability was the best. The laxity increased after resection of the RH. The laxity was more after release of the UCL than after resection of the RH (P < 0. 05). The greatest laxity was observed after resection of the RH together with release of the UCL, so its stability was the worst.Conclusion 1.The safe area exists in the radial head and it does not articulates with the ulnar radial notch. The range of non-contact of radian is 115.47±1.33°in men and 116.03±1.22°in women .It is safe when internal fixation are placed in this area and will not influence the rotation function of the forearm. 2. Because the anatomical parameters of men are slightly lager than that of women and are different among individuals, the design of radial head prosthesis with various types should be according to the gender and individuals. 3.The UCL is the primary valgus stabilizer of the elbow and the RH was a secondary constraint to resist valgus instability. 4.The resection of the RH is feasible when the fracture can not be replaced and fixed and does not have the injury of other tissue ; with the injury of the UCL , the resection of the RH can also be perfomed when the ligament is repaired simultaneously and effectively, prosthesis replacementis is recommended if necessory .
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