ObjectiveTo investigate the effectiveness of modified Stoppa approach with medial wall spring plate (MWSP) for involving quadrilateral of acetabulum fracture. MethodsBetween March 2008 and September 2013, 38 patients with involving quadrilateral of acetabulum fracture were treated, including of 23 males and 15 females with an average age of 36.08 years (range, 19-56 years). The causes included traffic accidents injury (21 cases), crash injury of heavy object (10 cases), and falling injury from height (7 cases). The interval of injury and admission was 3 hours to 2 days (mean, 11 hours). There were 12 cases of anterior column fracture (type D), 5 cases of transverse fractures (type E), 8 cases of T shaped fractures (type H), 6 cases of anterior column fracture with posterior transverse fractures (type I), and 7 cases of double column fractures (type J) according to Letournel-Judet classification. Based on fracture types, MWSP was used to fix fracture by modified Stoppa approach in 19 cases or combined with the ilioinguinal approach in 10 cases or combined with Kocher-Langenbeck approach in 9 cases. The operation time, blood loss, and complications were recorded. The effectiveness of reduction and the hip function were evaluated according to Matta score system and Merled' Aubigne and Postel score system. ResultsThe operation time was 85-210 minutes (mean, 130 minutes).The intra-operative blood loss was 450-900 mL (mean, 650 mL). There were 1 case of vascular avulsion, and 1 case of bladder injury during operation; there were 8 cases of venous thrombosis and 2 cases of fat liquefaction of incision after operation. Screw was implanted into the articular joint in 1 case on CT after operation. Matta X-ray assessment showed anatomical reduction in 9 cases, satisfactory reduction in 24 cases, and unsatisfactory reduction in 5 cases, and the satisfaction rate of reduction was 86.84%. Three patients had limb shorting of 0.8-1.0 cm when compared with normal limb. All patients were followed up for 7 to 18 months with an average of 10 months. Fractures healed well within 13-16 weeks with an average of 14 weeks. At 1 year after operation, the results were excellent in 9 cases, good in 21 cases, general in 5 cases, and poor in 3 cases, and the excellent and good rate was 78.95% according to the Merled'Aubigne and Postel hip score standards. ConclusionInvolving quadrilateral of acetabulum fracture can be fixed with MWSP by modified Stoppa approach or combined with other approaches to obtain good exposure, less invasion, satisfactory reduction, stable fixation, and low complications.