ABSTRACT
BACKGROUND:Chondrocytes may dedifferentiate when they are cultured in vitro,and the capacity of synthetizing glycosaminoglycan (GAG)is also reduced,how to delay the dedifferentiation of chondrocytes is a crucial topic in the field of tissue engineering.OBJECTIVE:To observe the performance of chondrocytes synthetizing GAG at different inoculum densities.DESIGN,TIME AND SETTING:A controlled cellular experiment was performed at the laboratory of Department of Orthopaedics in the Second Hospital of Shanxi Medical University between January 2007 and May 2007.MATERIALS:Five New Zealand rabbits of one month old were used in this study.METHODS:Articular chondrocytes were isolated from both knees and digested using 0.4% pronase enzyme and 0.025% Ⅱ type collagenase.The chondrocytes harvested from the same rabbit were divided into two sets,one was seeded at a constant density of 2×104/cm2 in primary and subculture,the other was cultured at a reduced density of 2×103/cm2 following cellular adhesion.Cellular morphology and proliferation were observed under inverted microscope.The culture media were renewed after the primary cells and passage 1 cells were confluent.MAIN OUTCOME MEASURES:GAG concentration was determined using the modified precipitation method with Alcian blue at 12,24,36,48 and 60 hours following the renewal of culture media.RESULTS:Articular chondrocytes in the primary high-density culture group were polygonal with clear boundaries,they have shown to form colony at 3-4 days.Cells around colonies were more slender than those in the center of colonies,shaping as long polygon.There was no obvious change observed in the morphology of passage 1 cells.In the low-density culture group,cells scattered at early stage and formed colonies at 7 days,cellular morphology showed no significant differences in comparison with high-density culture group.The time of primary cells becoming confluent in the low-density culture group was prolonged compared with high-density culture group.The GAG concentration in supernatants in the primary cells of low-density culture group was significantly lower than that in primary cells and passage 1 cells of high-density culture group (P＜0.001,P＜0.05).The GAG concentration showed a greater difference along with the prolonging of culture time.CONCLUSION:High-density culture is better then low-density culture to enhance the performance of chondrocytes synthetizing GAG and to retard the velocity of chondrocytes dedifferentiation,which suggests high-density culture contributes to maintain the chondrocytes phenotype and can be considered as a good way of plate culture.
ABSTRACT
[Objective]To discuss the operative treatments and evaluate the effects of reconstruction interlocking nail(RIN)in treating femoral shaft fractures associated with ipsilateral peritrochanteric fractures of the femur.[Method]A retrospective study was done on 37 patients with femoral shaft fractures combined with ipsilateral peritrochanteric fractures treated by RIN from September 2002 to Janurary 2009.This study involved 32 males and 5 females,with an average age of 36 years (range,24 to 69 years).Thirty-three patients had high-energy injury (26 of road accident,7 of falling from height),and 4 low-energy injury.Among them,13 patients had fractures in the upper one-third of the femoral shaft,18 in the middle one-third and 6 in the lower one-third.Six patients had open fractures (Gustilo scale Ⅰ in 1,and Ⅱ in 5).According to Garden classification for femoral neck fractures,there were 19 cases of type Ⅱ,9 cases of type Ⅲ and 2 cases of typ Ⅳ.According to AO classification for femoral intertrochanteric fractures,there were 3 cases of type A1.1,1 case of type A2.1.According to Seinsheimer classification for femoral subtrochanteric fractures,there was 1 case of type Ⅰ,and 2 cases of type ⅡA.The mean duration from injury to surgery was 3.7 days (range,4 hours to 13 days).After operation step-by-step functional rehabilitation was encouraged.[Result]The follow-up periods ranged from 14 to 38 months (average,24 months).Bony union was achieved in all patients.The average bony union time was 13 weeks for fractures of femoral shaft,14 weeks for femoral neck,12.6 weeks for intertrochanteric and 15.5 weeks for subtrochanteric fractures.Femoral head necrosis occurred in one case.No such complications as infection,loosening of nails,coxa vara,or malunion was found.According to Harris Scoring system,32 cases (86.5%)were rated as good or excellent.[Conclusion]The treatment of femoral shaft fractures associated with ipsilateral peritrochanteric fractures of the femur with RIN is a good method because of its advantages of small trauma,stable fixation,high union rate,few complications and good results.It may have fewer internal fixators.Carefully choosing suitable patients,sophisticated operation skills and active functional exercise after operation are keys to success.