cerebral palsy ( cp ) is caused by an injury to the immature brain usually occurring during or shortly after birth . although all functions of the brain may be affected , the motor function is usually the most vulnerable . the gross motor function classification system ( gmfcs ) categorises the functional capabilities of children with cp into 5 levels ( table 1 ) . the initial treatment usually involves a combination of interventions such as medicines , braces , and adaptive and assistive equipment ; however , surgery is sometimes warranted to control symptoms and maintain an optimum level of function and appearance . hip joint dislocation is a common problem in children with cp that can cause significant pain and interference with personal care and hygiene . surgical hip reconstruction reduces the hip joint through soft tissue releases and bony cuts of the femur and/or pelvis ( figure 1 ) . blood loss and subsequent blood transfusion are a normal consequence of hip reconstruction [ 3 , 4 ] . postoperative anaemia has been shown to impede functional ability and therefore delay discharge in this patient group . however allogeneic blood transfusion is associated with risks for the recipient ( haemolysis , infection , immunosuppression , transfusion - related acute lung injury , and even death ) . the risk of postoperative wound infection correlates with the amount of transfused allogeneic blood and has significant cost implications . there has been a recent surge in the use of tranexamic acid ( txa ) in trauma and orthopaedic practice . txa belong to a group of agents called  the antifibrinolytics  which has been used successfully to reduce blood loss . a cochrane review scrutinised 252 trials that had used antifibrinolytics in elective surgery : 60 trials evaluated txa . the reviewers concluded that antifibrinolytics are effective in reducing blood loss , the need for allogeneic red cell transfusion , and the need for reoperation due to continued postoperative bleeding after elective surgery . numerous other studies have confirmed the effectiveness of txa in reducing blood loss and transfusion requirements in total joints replacements and spine surgery [ 612 ] . however , there is very little published work on the use of txa in paediatric orthopaedic practice . in a multicenter , retrospective review of 84 patients with cp who underwent spinal deformity correction , the use of txa was associated with less blood loss and length of stay . very few surgeons use txa in hip reconstruction surgery for children with cp and , to the best of our knowledge , there is no available report on its effectiveness and safety profile in this group of patients . a retrospective observational study design , including 51 consecutive hip reconstructions performed between 2011 and 2013 , was used to evaluate the use of tranexamic acid ( txa ) . the study was approved by the institution 's audit department ( reference number 4942 ) . medical records were reviewed for age , date of birth , gender , medications , weight at surgery , blood loss in theatre , and the need for transfusion . the preoperative laboratory results of complete blood count including hemoglobin ( hb ) , platelets , and haematocrit ( hct ) were recorded . the estimated blood volume ( ebv ) was estimated from the following formula : ( ebv = 80  ml  body weight in kg ) . the estimation of red blood cell volume ( rbcv ) at preoperative hct is as follows : rbcvpreop = ebv   hctpreop . the estimation of red blood cell volume ( rbcv ) at postoperative hct is as follows : rbcvpostop = ebv   hctpostop . the total blood loss is calculated from the fall in red blood cell volume : blood loss = rbcvdiff / hctpostop [ 14 , 15 ] . the data were checked for normality using the kolmogorov - smirnov test ( kst ) and the shapiro - wilk test ( swt ) . when substantial nonnormality was indicated ( p < 0.05 ) , continuous outcomes were analysed ( blood loss , volume transfused , length of stay , haemoglobin and haematocrit , and overall cost ) , using independent samples t - test . categorical outcomes were analysed by fisher 's exact test ( blood transfusion required , gmfcs levels , and complications ) . fifty - one hip reconstructions were performed in children with cp in our institute : 14 received txa , 37 did not . the two groups were similar in age , weight , gender distribution , and the asa physical status ( the american society of anesthesiologists ) ( see table 2 ) . baseline mean operative hb levels and hct levels were similar , as were proportions of patients taking nonsteroidal anti - inflammatory drugs ( nsaid ) and epilim : these are implicated with increased surgical blood loss [ 17 , 18 ] . patients in the tranexamic acid group had a higher gmfcs level ( 78% versus 75% : p = 0.79 ) , more combined pelvic and femoral osteotomies ( 78% versus 67% : p = 0.62 ) , and more bilateral surgery ( 57% versus 27% : p = 0.06 ) . although none of these differences reached a statistical significance , the latter had come quite close . bilateral hip reconstruction was performed in 57% of children in the txa group in comparison to 27% in the other group ( p = 0.06 ) ; thus the txa group may have more severe underlying disease . there is a borderline significant different in the pattern of gross motor function classification system ( gmfcs ) between groups , despite no systematic trend by level ( p = 0.79 ) . the proportion of children receiving blood transfusion was 42.9% in the txa groups versus 36.1% in the non - txa group , a statistically nonsignificant difference ( rd : 6.7% , 95% ci : 21.3% to 36.1% , p = 0.75 ) ( table 3 ) . the total blood loss was estimated using gross 's formula [ 14 , 15 ] . the mean total blood loss was similar : txa 969  ml versus no txa 971  ml ( rd : 2  ml , 95% ci : 536  ml to 531  ml , p = 0.99 ) . hemoglobin ( hb ) and hematocrit ( hct ) were tested on postoperative day 2 unless there was a clinical need to do these earlier . the duration of stay in hospital was similar between groups : txa 8.17d versus no txa 7.63 ( difference : 0.54  d , 95% ci : 2.37 to 3.45 ) , p = 0.71 . there were 3 complications in the tranexamic acid group ( 2 fragility fractures and 1 paralytic ileus ) . two complications were recorded in the non - txa group : one deep infection and a pressure sore . the former was treated with washout and antibiotic and the latter was treated with regular dressing . this retrospective study was conducted to explore the transfusion rate in children with cerebral palsy who underwent hip reconstruction as a background work for a future trial . blood transfusion rate is considered to be a reliable outcome measure and it is of great importance for patients , healthcare providers , and managers and hence it is chosen as the primary outcome for our study . a recent local audit showed that the our unit was 96% compliant with the national guidelines for blood transfusion [ 19 , 20 ] supporting the findings and subsequent conclusions of this study . out of 51 hip reconstructions , 13 patients ( 25.4% ) received allogenic blood transfusion . contrary to most studies [ 5 , 11 , 12 ] that used txa , in children with cp and hip reconstruction , transfusion rate was higher , postoperative hb was lower , and patients stayed longer in the txa group . this did not reach a statistical significance ( p = 0.75 , 0.5 , and 0.71 , resp . ) . this may be a true finding that txa does not reduce blood loss in this group of patients or it may be a type ii error where the study did not demonstrate the real positive effect of txa on blood transfusion for various reasons . the table of baseline characteristics of the study populations showed significant selection bias which disfavours txa . more than half of the patients who had txa underwent bilateral hip reconstructions in comparison with 27% only in the non - txa group . bilateral hip reconstructions mean more surgery , more blood loss , and more blood transfusion . the patients who had txa were significantly more disabled as evident by the higher proportions of patient with worse gmfcs levels . it is expected that these factors would mean more transfusion rates in the txa group and nevertheless this was not the case . similar can be said on length of stay where patients who received txa stayed longer in hospital . eipe and ponniah   showed that surgical blood loss was underestimated by 64% using clinical methods assessing blood soaked mops and gauze pieces and measuring blood lost to suction bottles and the vacuum drain . , total blood loss was estimated using gross 's formula [ 14 , 15 ] . it is a retrospective study where data were collected from medical records and hospital laboratory . although this may undermine the accuracy of data , most primary outcomes ( blood transfusion , hb level , and length of stay ) are accurately and independently recorded in our center . it is estimated that 184 patients are required to have an 80% chance of detecting a 50% decrease in the transfusion rates of 36% in the non - txa group at the 5% level . the rate of the type ii error is closely related to the number of participants involved in a study ( the study power ) . in conclusion , although we have not been able to demonstrate the value of txa in reducing blood loss and transfusion rate in children with cp who underwent hip reconstruction , it is hoped that an interest in exploring the value of txa in paediatric orthopaedic surgery is generated . ideally this should be explored further in an adequately powered , randomised controlled trial where risk of bias is minimized .
this is a retrospective study of 51 consecutive hip reconstructions in children with cerebral palsy performed between 2011 and 2013 . 
 tranexamic acid ( txa ) was used in 14 hip reconstructions only . 
 transfusion rate was higher , postoperative hb was lower , and patients stayed longer in the txa group . 
 this did not reach a statistical significance ( p = 0.75 , 0.5 , and 0.71 , resp . ) . 
 more than half of the patients who had txa underwent bilateral hip reconstructions in comparison with 27% only in the non - txa group . 
 bilateral hip reconstructions mean more surgery , more blood loss , and more blood transfusion . 
 the patients who had txa were significantly more disabled as evident by the higher proportions of patient with worse gmfcs levels . 
 although we have not been able to demonstrate the value of txa in reducing blood loss and transfusion rate in children with cp who underwent hip reconstruction , it is hoped that an interest in exploring the value of txa in paediatric orthopaedic surgery is generated . 
 ideally this should be explored further in an adequately powered , randomised controlled trial where risk of bias is minimized .