[Clinical outcome of minimally invasive internal fixation of pelvic ring injuries with cannulated screws].

Objective: To evaluate the safety and reliability of percutaneous internal fixation for pelvic ring injuries with cannulated screws.

Methods: Forty-eight patients (21 male and 27 female, aged from 17 to 61 years with an average age of 38 years) with unstable pelvic ring injuries were treated with closed reduction and percutaneous cannulated screws fixation under C-arm fluoroscopic guidance. According to Tile's classification, the patients were classified into type B1 in 4 cases, B2.1 in 8, B2.2 in 10, B3 in 4, C1 in 11, C2 in 7 and C3 in 4. Among them, 39 patients were treated with anterior and posterior fixation, 4 were treated with anterior fixation, and 5 were treated with posterior fixation alone. Anteroposterior, inlet and outlet X-ray radiographs and CT scans of the pelvis were taken preoperatively to evaluate the stability and deformities, and after surgery the plain radiographs and CT scans were taken to evaluate the reduction and the location of screws.

Results: The average operative time was 55 minutes (range, 15 to 95 minutes), and the average intraoperative blood loss was 60 ml (range, 15 to 150 ml), no patient accepted blood transfusion during or after operation. All 48 patients were inserted 157 cannulated screws (mean 3.3, range 2 to 8 per patient). Forty-two patients (135 screws) underwent postoperative pelvic CT scan and 91.11% (123 screws) of them was considered in optimal location; 7 screws penetrated the wall of pelvis and acetabulam because of overlength (<0.5 cm) or deviation, 5 screws interfered with the sacral canal or foramen. Fortunately, these 12 screws did not cause any symptom to the patients. The average follow-up period was 13 months (range 8 to 49 months), the displacement of injured pelvis was satisfactorily corrected in 45 patients (93.75%) and the fractures were healed at one stage. Among all patients, 40 cases (83.33%) had returned to their original works, 4 were still in the process of recovery at the last follow-up and the other 4 were unemployed as sciatic nerve injury or amputation. According to Lindahl improved standard of functional assessment of pelvic injury, the result was excellent in 35 cases, good 10 and fair 3, the average score was 78.7.

Conclusion: With better understanding of the pelvic anatomy, and under C-arm fluoroscopic guidance, treatment of closed reduction and percutaneous cannulated screw internal fixation for unstable pelvic ring injuries is a safe, reliable and feasible method. The clinical outcome is satisfactory.