The Theoretical And Experimental Research Of The Absorbable Patella Net

Objective:A method about using absorbable patella net(APN) to fix petella fracture model is researched by preliminary study of APN. With biomechanical comparison to AO method, this method is expected to a new approach to clinically treat petella fracture in the future.Methods:1. Choose PGLA absorbable line to braid a net according to the shape of petella.2. Take out 20 wet speciments knees from 10 adult cadavers,10 for each sex or each side. Then cut the petella at the midpoint with a hacksaw, make them into transverse fracture models and fix the models with two methods using absorbable petella net and K-wire tension band (KWTB). Divide these models randomly into two groups:A is absorbable petella net group, and B is K-wire tension band gruop. Bend them to eighty angle and irradiate with X-ray.3. Fix the AB groups on the mechanical tester (MTS), make a mechanical loading test.4. After mechanical loading test all the specimens are removed.Different separation distances between fracture ends are got.5.Using t test to analyse all the date.Results: 1. As weaving fishing nets, the APN are braided manually to a rectangular form, with 10 PGLA lines of 4th. And the APN, whose size approximates to patella, is 4cms long and 3cms wide, arranging into 4 rows in which each row contains 5 mesh with a size of 0.8X0.7cm. The net line leaves a 6cm tail with a needle.2. Bend knee to eighty angle and irradiate with X-ray.The results show that fractures are unseparated and unshifted with good alignment an, and the internal fixations are not loosing.3. Make machanical tests of APN group and KWTB group under 0-100N loading. The results show that the distances of fracture ends fixed by both methods. The distance in A group shows 0.0280±0.0063mm when the loading is I0N.While 50N the distance is 2.4200±0.4814mm, 70N is 5.2540±0.1556mm, and when the loading is 100N the distances is 11.261±0.5874mm.The distance in B group shows 0.0290±0.0074mm when the loading is 10N.While 50N the distance is 2.7420±0.4707mm,70N is 5.4020±0.2009mm, and when the loading is 100N the distances is 11.1617±0.4788mm.The results show that the distances of fracture ends fixed by both methods have no obvious statistical significance(P>0.05).4. Make machanical tests of APN group and KWTB group undermechanical loading.A group is 1.310±0.19mm and B group is 1.440±0.158mm. The results show that the distances of fracture ends fixed by both methods have no obvious statistical significance (P>0.05).Conclusion:These experiments preliminaryly indicate that APN is consistent with biomechanical principles, with effect approximated to the AO method.