Biomechanical Comparison Of Patella Fracture Treated With Tension Band Absorbable Suture And Tension Band Wiring

Objective: In recent years, with the development of transport and sportcareer, the incidence of patella fracture has been increasing. For patellafracture, the most widely used method is K-wire and tension band wiringfixation.The advantage of K-wire and tension band wiring fixation method issimple,cheap price,conforming to biomechanics,relatively stable,applicableto all types of patellar fracture;however, there are also some disadvantagessuch as steel nodular skin irrigation,wire loose or break,stell wire has to beremoved after the healing of fracture,and so on. In recent years, absorbableimplants gradually applied to clinic with the development of BiomedicalEngineering. Some scholars believe that the application of tension bandabsorbable suture for patella fracture can avoid various defects of tensionband wiring, and some scholars used different kinds of tension bandabsorbable suture in the treatment of patella fractures and achieved goodtherapeutic effect according to literature.This experiment based on transversefracture of the patella model respectively using K-wire and tension bandwiring and four kinds of tension band absorbable suture,a total of fivetreatment methods for biomechanical comparison.the stability was tested toprovide a theoretical basis for clinicians to choose the treatment of patellafracture.Method: The transverse fracture model of the patella was made in4keenjoints of adult cadaveric.The test methods of fixation were Similar, patellaspecimens were not destroyed after test, thus the patella specimens could bereused.The femur and the tibia of the specimen were fixed on the homemadeclamp,the femur was parallel to the ground and the knee was flexed36°.First,the patella fracture was anatomically reducted,then each of the patellaspecimens were sequentially fixed with five methods: two kinds of tension band absorbable suture,K-wire and tension band absorbable suture,K-wireand tension-band absorbable suture combined with patella and tibial tuberclecerclage by absorbable suture, K-wire and tension band wiring.The quadricepsfemoris of specimens were pulled by CSS-44020biomechanics machine,andthe tensile strength was recorded when the internal fixation was failure.Wedefined that the internal fixation was failure when the separation distance ofthe patella fracture was2mm under tension.Result: The tensile strength of each group when the internal fixation wasfailure:(group A)the first kind of tension band absorbable suture:166.500±6.350N；(group B)the second kind of tension band absorbable suture:226.250±6.500N；(group C)K-wire and tension band absorbable suture:228.500±19.226N；(group D)K-wire and tension-band absorbable suture combined withpatella and tibial tubercle cerclage by absorbable suture:425.500±18.734N；(group E)K-wire and tension band wiring:480.750±15.370N.There were statistical significances(p＜0.05) in comparison between anytwo groups except between group B and group C.Conclusions：1The stability of internal fixation groups: K-wire and tension band wiring＞K-wire and tension-band absorbable suture combined with patella and tibialtubercle cerclage by absorbable suture＞K-wire and tension band absorbablesuture＝the second kind of tension band absorbable suture＞the first kind oftension band absorbable suture.2The stability of the first kind of tension band absorbable suture is poor,should not be used for the treatment of patellar fracture3The stability of the second kind of tension band absorbable suture andK-wire and tension band absorbable suture are not sufficient to support the early functional exercises of the knee. If these two fixtion methods areapplied,we propose a plaster external fixation postoperative.4The stability of the K-wire and tension band wiring is better than K-wire andtension-band absorbable suture combined with patella and tibial tuberclecerclage by absorbable suture, these two fixtion methods can withstand thetension of quadriceps femoris more than425N,and withstand the patello-femoral pressure at the same time. If these two fixtion methods are applied,the patients can take early functional exercise of the knee postoperative.5Patella and tibial tubercle cerclage by absorbable suture can be used for aadjuvant treatment of patellar fracture.6Although the absorbable suture has good biological characteristics, but forpatellar fracture, it cannot provide static compression at both ends of the fract-ure,and it is more flexible, so the stability of fixation with absorbable suture isnot enough.we do not recommend to use absorbable suture instead of steelwire for the treatment of patellar fracture, it is mainly applied to the assistedfixation of patella fracture. If the tension band absorbable suture was applied,patella and tibial tubercle cerclage by absorbable suture must be used forprotection.