Objective To investigate the indications,techniques and effects in surgical treatment of stale acetabular comminuted fractures.Methods A retrospective review was made on 24 cases (24 hips) of obsolete acetabular fractures undergone delayed reconstruction due to the combined injuries in other organs from October 2003 to June 2010.There were 18 males and 6 females,at 22-68 years of age [mean (42.2 ± 10.5) years].Mean time from injury to operation was (4.6 ± 1.3) weeks (range,3-6 weeks).According to Letournel classification,there were 11 simple fractures including six posterior wall fractures,one anterior wall fracture,one posterior column fracture,one anterior wall fracture and two transverse fractures and 13 compound fractures including six posterior column with posterior wall fractures,two transverse with posterior wall fractures,one T-shape fracture,two posterior semitransverse fractures and two both-column fractures.Surgery was performed via ilioinguinal approach in two cases,posterior acetabular approach in 13 and the combined approaches in nine.Results All 24 cases were available to average (15.6 ± 10.5) months of follow-up (range,10-36 months).Quality of reduction based on Matta standard was anatomic in 21 cases,unsatisfactory in two and poor in one.Clinical results evaluated using modified d' Aubigne-Postel score were excellent in 21 cases,good in two and poor in one.There were one femoral head necrosis,11 heterotopic ossification and six sciatic nerve transient palsy after operation.Conclusion Delayed open reduction and internal fixation is effective in treatment of obsolete acetabular comminuted fractures.