acetabular fracture types are usually determined by two classifications : arbeitsgemeinschaft fuer osteosynthesefragen - association for the study of internal fixation ( ao / asif ) and leotournel and judet ( l - j ) . according to the l - j classification , the five elemental fractures are : ( a ) posterior wall , ( b ) posterior column , ( c ) anterior wall , ( d ) anterior column , and ( e ) transverse . the five combined fractures are : ( a ) posterior column and wall , ( b ) transverse and posterior wall , ( c ) anterior column and posterior hemitransverse , ( d ) t - type , and ( e ) both columns . the ao classification   describes three types of fracture : ( a ) type a , partial articular , involving only one of the two columns , which includes three subgroups : a1 , posterior wall fracture , a2 , posterior column , and a3 , anterior column or wall ; ( b ) type b , partial articular , involving the transverse component , which includes b1 , pure transverse ; b2 , t - shaped ; and b3 , anterior column and posterior hemitransverse ; and ( c ) type c , which are complete articular fractures and involve both columns , including c1 , high variety , extending to the iliac crest ; c2 , low variety , extending to the anterior border of the ilium ; and c3 , extension into the sacroiliac joint . however , transitional types of acetabular fracture might occur , which are difficult to classify but can often be matched to well - described fractures . the acetabular fracture reported in this case is not described in the ao / asif or l - j classification and can not be matched to a transitional type fracture . a 46-year - old man in good physical health was admitted to another hospital following a car accident . the patient presented an impacted fracture of the posteroinferior articular surface of the acetabulum with comminution of the quadrilateral lamina . surgical treatment was performed using the kocher  langenbeck approach , and the patient was placed in the prone position . the posterior column of the acetabulum did not show cortical interruption , and so a small hole was made using the scalpel to lift up the posterior wall . when the impacted fragment was retrieved , an autologous bone graft from the greater trochanter was used to fill the bone defect . a four - hole plate was shaped like a bracket to hold the osteochondral fragment in place because it tended to fall out . in addition , the fragment of posterior wall made by the osteotomy was replaced and stabilized with a six - hole plate . postoperatively , a computed tomography ( ct ) scan was performed to check the position of the impacted fragment . three years after surgery , the patient had a normal hip range of motion without pain . no limitation in activities of daily living was reported , and now the patient plays american football . the acetabular fracture described in this case report can not be placed in the ao / asif or l - j classifications or be matched to transitional types . in this case , both columns were intact , but there was a deep impaction with dislocation of the posteroinferior articular portion and comminution of quadrilateral lamina and ischiatic bone fracture . a posterior wall fracture is characterized by the presence of an impacted articular fragment . in young men , this fracture is often combined with hip dislocation , thus provoking trabecular bone compression and osteochondral fragment impaction . in patients over 50 years of age , especially in women , osteochondral impaction also occurs without hip dislocation due to reduced bone strength , as in osteoporotic bone or fractures in the elderly [ 2 , 3 , 6 , 8 ] . quadrilateral lamina fracture is often combined with anterior column / wall fracture and fracture of both acetabular columns . in this case , both columns were completely intact , and so it was not referable to known acetabular fracture types . after the uniqueness of this fracture had been verified , the choice of treatment had to be made . impaction of the posteroinferior articular surface might lead to rapid osteochondral degeneration with secondary hip arthritis . to help determine whether it was better to perform surgical treatment and reduce the impacted fragment , a ct scan of the acetabulum was performed and carefully analyzed and showed a large impaction of articular fragment . an articular fracture was detected in eight ct - scan slides involving > 2  cm of the articular surface , as each ct - scan slide measures 3  mm . therefore , the decision to perform a surgical reduction of the fracture was reached ( figs .  1 , 2 , 3 , 4 , 5).fig .  1a x - ray of the pelvis showing fracture of upper part of the ischium in the lateral part of the obturator foramen . b , c computed tomography ( ct ) showing the impacted fragment of the articular surface and comminution of thelamina quadrilatera . f 3d ct highlighting the well - impacted articular fragment and involvement of thelamina quadrilatera . the anterior and posterior columns are intactfig . the second plate is under the ischium to maintain reduction of the intra - articular fragment and a fragment of thelamina quadrilaterafig . 5x - ray after 3  years showing a good clinical result a x - ray of the pelvis showing fracture of upper part of the ischium in the lateral part of the obturator foramen . b , c computed tomography ( ct ) showing the impacted fragment of the articular surface and comminution of thelamina quadrilatera . f 3d ct highlighting the well - impacted articular fragment and involvement of thelamina quadrilatera . the anterior and posterior columns are intact a , b intraoperative image of the intact posterior column . after osteotomy of the posterior wall , the impacted fragment was reduced a  c postoperative x - ray . the second plate is under the ischium to maintain reduction of the intra - articular fragment and a fragment of thelamina quadrilatera postoperative computed tomography highlighting reduction of the intra - articular impacted fragment x - ray after 3  years showing a good clinical result with regard to the surgical approach , the ilioinguinal approach combined with the stoppa approach [ 1 , 5 ] enables a quadrilateral lamina fracture to be detected , but in this case , there was not enough space to see the impacted fragment , reduce , and stabilize it with a plate . three years after surgery , the patient had a normal hip range of motion , no pain or limitation in activities of daily living , and now plays american football . managing a unique kind of acetabular fracture is reported in this article . due to its rarity , it was extremely hard to decide whether to treat it surgically and , if so , by which approach . we concluded that the surgical technique chosen allowed adequate reduction of the articular fragment , good stability of the fracture , and an excellent clinical outcome 3  years after the operation .
surgical treatment of a unusual acetabular fracture is described . 
 this fracture was characterized by impaction and breaking down of the posterior articular surface and comminution of lamina quadrilatera lower portion , without cortical fracture of both columns . 
 the fracture was treated surgically through the kocher  langenbeck approach . 
 a small hole was created in the acetabulum posterior wall , the impacted fragment was reduced , and the bone defect was filled with autologous bone from the greater trochanter . 
 a plate was shaped in order to fix both bone graft and fractured fragment .