The Effect Of PDLLA Rods On The Development Of Epiphyseal Plate: An Experiment And Clinical Study

PartⅠThe Effect of PDLLA Rods on the Development of Epiphyseal Plate: An Experiment Study on Growing RabbitBACKGROUND CONTEXT:Epiphyseal fractures occupy approximately 15% of pediatric fracture of long bone.Generally, closed treatment of fractures is preferred in children for its growth characters,however, there are a few epiphyseal fractures on which internal fixation including transphyseal placement of pins across fracture lines is inevitable. Traditional Kirschner wire has been used with great success. However, these pins require removal and there are a small incidence of pin tract infection,these give rise to physical and phychological injuries of children. Absorbable materials have been used since the 1980s for internal fixation of fractures as an alternation of metallic materials, the first report of absorbable implants placed into physis in children was 1989.Lactic acid materials have been used as sutures in surgery for many years ,they are better biocompatible and biodegradable compared to polyglycolic acid and polydioxanone and are more hopeful internal fixator.In this study, absorbable PDLLA rods of different diameters were implanted across the distal femoral epiphyseal plate to study the effect of PDLLA rods on the development of epiphyseal plate , in order to provide theoretic basis for the application of PDLLA rods in the internal fixation of epiphyseal fractures.Objective:This study is designed to assess the effect of poly-DL -lactide (PDLLA) rods across the distal femoral epiphysis on the development of epiphyseal plate in skeletally immature New Zealand write rabbit.methods:The 75 New Zealand white rabbits were divided into three groups, A PDLLA rod with 1.5 mm,2.2 mm,3.2mm in diameter and 25mm in length was driven into a drill hole of equal bore in the intercondylar portion of the right femur across the central portion of growth plate , a corresponding 1.5mm,2.2 mm or 3.2mm empty drill hole was made across the left femoral physis served as a control. The animals were sacrificed at 3,6,9,12 and 24 weeks postsurgery. the percentage of injured growth plates, Radiographs, both femur length measurements, radiographic measurement of femora condyle angles, histology sections and transmission electron microscope of the physis and adjacent bone tissues were made to evaluate the effect of PDLLA Rods on the development of epiphyseal plate.Results:The percentages of injured growth plate were (1.86士0.10)%,(4.03士0.52)%,(7.52士1.02)% in l.5mm,2.2mm,3.2mm groups.There was no visible difference in both femur length,valgus of varus angle . There was no significant evidence of inflammation of the growth plate too ,only nonspecific foreign body reaction could be seen during the follow-up period. 1.5mm and 2.2mm groups didn't cause visible growth disturbance while 3.2mm group caused growth disturbance.conclusions:1. PDLLA rod itself does not cause any disturbance of the epiphyseal plate .2.the growth disturbance of epiphyseal plate is related to the percentages of injured epiphyseal plate,the destruction of 7% or more area of epiphyseal plate will cause the growth disturbance.PartⅡThe Effect of PDLLA Rods on the Development of Epiphyseal Plate: An Clinic StudyBACKGROUND CONTEXT:Manipulative reduction and external fixation or Kirschner wire internal fixation per cutem are often adopted in epiphyseal fracture of children to avoid further injury of epiphyseal plate, but for obviously displace or unstable epiphyseal fracture, open reduction and internal fixation are still necessary. Traditional internal fixation for epiphyseal fracture is metallic pin that need to be taken out for the second operation to avoid effecting the growth of epiphyseal plate . Absorbable materials are a new type of internal materials for othopadics clinic ,it are biodegradable,harmless in vivo and don`t need to be taken out for the second operation,which reduce patient suffering and economy burden.Meanwhile absorbable materials don`t lead to stress block with its degradation,so absorbable fixation materials would seem especially suitable for treating epiphyseal fractures.Objective:To explore the clinical results and the effects of the development of epiphyseal plate in treating epiphyseal fractures with PDLLA pod.methods:To collect 21 patients with epiphyseal fracture that were fixed with PDLLA pods from 2001.10~2006.10 , 21 males and 5 females were concluded, age range from 2 to 16 years , Postoperative recovery of patients were understood by observing fracture healing and the growth of injuried epiphyseal plate and function recovery.Results:The patients were followed up for 6 to 60month(mean: 32month). Primary healing was achieved for all patients'incision,all fractures were unionized well too. No nonunion and no delayed union occurred. According to the criteria set by xiao rui ,the results of treatment were evaluated as excellent in 16 patients and good in 3 patients. The excellent and good rate was 90%. there were two patients who had growth disfunction of epiphyseal plate.conclusions:PDLLA pod is safe and reliable for the treatment of epiphyseal fractures and don't cause harmful effects to epiphyseal growth.