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Objective To analyze the feasibility and practicality of the navigational template for antegrade lag screw fixation of the fractures in the posterior column of acetabulum.Methods Spiral CT scan data of 40 normal adult pelvis was collected.3D CT scans of pelvics were performed.Virtual 3D pelvic models were reconstructed with software Mimics 10.01.Virtual cylindrical implants were placed along the longitudinal axis of the acetabular posterior column via the ischial tuberosity among the ipsilateral hemipelvis and some anatomical parameters were measured.To adjust cylinder position to determine the best projection point,the shortest distance of the point to the linea terminalis and the anterior border of the auricular surface,the angle between the cylindrical and the coronal plane (α),and the angle between the quadrilateral district and iliac fossa plane (β) were measured respectively.The 3D models were imported into software UG 6.0.The models of navigational templates were designed according to the anatomic features of the acetabulums and the measured parameters.16 cases of dry left side of pelvis specimens were collected.Simulate acetabular posterior column screw fixation from different screw holes and verify the accuracy of navigation template assisted in the nail.Results The navigational templates was designed and manufactured successfully which was more consistent with the anatomical features of the quadrilateral plane.Placement of lag screw from the first hole:6.3％ achieved accurate positioning,75％ well positioning,and 18.7％ loose.From the second hole:81.3％ had accurate positioning,18.7％ well positioning.From the third hole:37.5％ had accurate positioning,62.5％ loose.Conclusion The navigational template designed according to the anatomic features of acetabulum and the measured parameters can accurately assist lag screw placement.
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Objective To discuss the mechanism of injury,treatment decisions,complications and surgical results of the floating hip injuries (FHI).Methods Thirty-three patients with FHI were retrospectively analyzed in our hospital from June 2001to June 2011.There were 25 males and 8 females,with an average age of 34.6 years (range,4-73 years).The mechanism of injury was motor vehicle collision for 20 patients,fall down from a height for 11,crushed injury for 1,and sports-related injury for 1.According to Liebergall classification for the floating hip injuries,there were 7 cases for type Ⅰ (21.2％),9 for type Ⅱ (27.2％)and 17 for type Ⅲ (51.6％).All patients had associated injuries,the average injury severity score (ISS) was 28.9.Thirty-two of the femoral fractures underwent surgical stabilization of their femoral fractures.Surgical stabilization methods included ORIF or intramedullary nailing (29 cases),external fixation (1 case),total hip arthroplasty (2 cases).Acetabular fractures were treated with open reduction and internal fixation (ORIF) in 16 cases.Thirteen patients suffered pelvic fractures underwent surgical stabilization for at least one component of ring disruption.Results Twenty-eight cases (84.8％) were followed up for 2.3 to 10.1 years (average,3.5 years).Thirteen patients were followed up in the 16 patients who suffered type Ⅰ or Ⅱ fractures.According to Majeed functional evaluation,the results were excellent in 8 cases,good in 3 and fair in 2,with the excellent and good rate being 84.6％.Fifteen patients with type Ⅲ were followed up,according to D'Aubigné and Postel evaluation criterion.The joint functions were excellent in 7 cases,good in 4,fair in 3,and poor in 1,with the excellent and good rate being 73.3％.According to Ma Yuanzhang functional evaluation,the knee functions of the all patients were excellent in 23 cases,good in 3,and fair in 2,with the excellent and good rate being 92.9％.Complications seen in these patients included post-traumatic osteoarthritis of the hip developed in one hips,2 patients developed heterotopic ossification (HO),one case of avascular necrosis of the femoral head,and two femoral nonunions.The most severe complication was traumatic sciatic nerve palsy,which was found in 5 patients.Conclusion Ipsilateral injuries to the femur and the pelvis or acetabulum (floating hip) are severe injuries usually caused by high-energy trauma.The femur fracture will most commonly be addressed first,and surgeons should be aware of the high incidence of sciatic nerve palsy as well as treatment options and potential complications associated with this devastating combination of injuries.