Treatment of unstable pelvic fractures with sacroiliac screwing assisted by 3D printing technique in combination with front ring nail-rod system

Objective To explore the clinical efficacy of 3D printing technique in assisting sacroiliac screwing in combination with front ring nail-rod system for treatment of unstable pelvic fractures. Methods From July 2015 to June 2017, 3D printing technique was used to assist the sacroiliac screwing in combination with front ring nail-rod system for 16 patients with unstable pelvic fracture at Orthopaedic Center, The Fourth People's Hospital of Zigong. They were 9 males and 7 females, aged from 19 to 60 years (average, 39.8 years). By the Tile classification, 5 cases were type B1, 6 type B2, 3 type B3 and 2 type C. Their operation duration, bleeding, fluoroscopy frequency, incision length, postoperative fracture reduction, success rate of sacroiliac screwing, accuracy of sacroiliac screwing, perioperative complications, weight-bearing exercise time, fracture healing time and the Majeed scores at the last follow-up were documented. Results All the 3D models and navigation templates were successfully designed and printed. Surgery succeeded in all the patients. Follow-ups ranged from 6 to 18 months, averaging 13.3 months. The bleeding ranged from 100 to 250 mL, averaging 162.4 mL; the operation duration ranged from 60 to 120 min, averaging 73.2 min; the intra-operative fluoroscopy frequency ranged from 13 to 31 times, averaging 17.4 times; the incision length ranged from 16 to 32 cm, averaging 21.1 cm. All the incisions healed by the first intention and all the fractures obtained osseous union after 90 to 120 d (average, 102.3 d). No significant complications like neurovascular injury or pulmonary embolism happened. The weight-bearing exercise time ranged from 25 to 40 d, averaging 31.5 d. According to the Matta imaging scores, the reduction was rated as excellent in 12 cases and good in 4. Altogether 28 screws were inserted with a success rate of 100%. Compared with the preoperative simulated screwing, the actual screwing angle deviated postoperatively by 0.12°±0.32°, the X axis by 0.36±1.24 mm, the Y axis by 0.36±1.24 mm and the Z axis by 0.22±1.26 mm, showing no statistically significant difference between the actual 3D deviations and the test value of 0 (P>0.05). Conclusion In the treatment of unstable pelvic fractures, 3D printing technique can be used in preoperative preparation of the connecting rod in the front ring nail-rod system to assist the sacroiliac screwing, significantly shortening the operation duration, reducing bleeding, ensuring safe and accurate screwing, and facilitating functional recovery. Key words: Pelvis; Fracture fixation, internal; Bone nails; 3D printing technique