The Effect Of Variable Fragment Size Of Posterior Wall Acetabular Fractures On Functional Outcome

Objective:The purpose of this retrospective study was to evaluate whether the variable fragment size of involving posterior wall acetabular fractures, including posterior wall fracture, posterior column and wall fracture, transverse and posterior wall fracture, have an effect on hip joint functional outcome.Methods:Fifty-two patients with involving posterior wall acetabular fractures were surgically treated in our traumatic orthopedics department between June2007and October2013. Four cases were excluded, as one was treated with total hip replacement and three had no CT data. The remanent48research cases included seventeen posterior wall fractures, eleven posterior column and wall fractures, twenty transverse and posterior wall fractures. These cases were divided into Aκ(11cases),Bκ(23cases),CK(7cases),Dκ(7cases) four groups base on the percentage of remaining intact posterior acetabular arc(K, Acetabular Fracture Index, AFI):Aκ≤25%,25%<Bκ≤50%,50%<Cκ≤75%,75%<Dκ≤1. For every case, the AFI was measured and calculated by PACS software and detailed demographic data, injuring reason, combined injury, operation waiting time, operative duration, blood loss, complication, Matta radiological Score, Brooker grading of heterotopic ossification, Merle’d Aubigne and Postel functional score were recorded. The statistical non-parametric test and Ordinal Regression were used to analyzed all the data.Results:The mean κ of each group were Aκ14.3%, Bκ35.9%, Cκ59.5%, Dκ81.2%. The average follow up period A group was36months (10～68months), B group was23.7months (6～63months). C group was22.9months (13～36months). D group was22.6months (6～47months). There were no statistical significance of all kinds of clinical data between A,B,C,D groups. For functional outcome, A group showed2excellent result cases,5good,1fair and3poor, the rate of excellent and good was63.6%). B group showed10excellent,9good,4fair and0poor, the rate of excellent and good was78.3%. C group showed4excellent,3good,0fair and1poor, the rate of excellent and good was85.7%. D group showed4excellent,3good,0fair and0poor, the rate of excellent and good was100%. For radiological outcome,2traumatic arthritis cases occured in A group,1avascular necrosis of the femoral head case occured in C group,6heterotopic ossification cases(3Brooker Class I and3Class II) occured in A group and7(5Class I,1Class II and1ClassIII) in B group. For Matta radiological results, A group showed4anatomical reduction cases,6good,1poor. B group showed16anatomical,4good,3poor. C group showed4anatomical,3good. D group showed5anatomical,2good. The reduction quality, AFI (κ), rehabilitation and follow-up time, associated with lower limb fractures and avascular necrosis of the femoral head were factors which influenced final functional outcome. The better of Matta Score (OR=4.21, P=0.009) and the bigger of the κ(OR=2.56,P=0.017), the higher of the functional score. The functional outcome of rehabilitation and follow-up time more than12months (OR=0.15, P=0.038) was better than that less than12months. The lower functional score had been got when combined with lower limb fractures (OR=0.13, P=0.022) or complicated with avascular necrosis of femoral head (OR=0.02, P=0.042)Conclusion:The hip joint functional outcome has a negative correlation with the size of posterior wall acetabular fracture fragment, the bigger of the size of fracture fragment, the worse of function. Factors affecting function are in sequence of reduction quality>AFI (K)>rehabilitation and follow-up time>associated with lower limb fractures>avascular necrosis of the femoral head. The best time for hip joint functional rehabilitation is the12months after operation.