The anterior subcutaneous internal fixator (ASIF) for unstable pelvic ring fractures: clinical and radiological mid-term results

Abstract

Purpose: The purpose of this study was to determine the outcome of unstable type C pelvic fractures treated with posterior stabilisation and the anterior subcutaneous internal fixator (ASIF).

Methods: Altogether, 36 consecutive patients were treated for unstable type C pelvic ring fractures using posterior stabilisation and ASIF. After a minimum of 18 months, the clinical and radiological outcome was retrospectively investigated.

Results: Overall, three patients (8.3%) died, and 31 patients (86%) were available for follow-up after a mean of 4.5 years. Thirty of 31 patients (97%) showed radiographic bone consolidation of both the posterior and anterior pelvic ring. Only one non-union and two infections due to the anterior device were observed. The total German pelvic outcome score showed an excellent or good rating for 64.5% of the patients, and a fair or poor for 35.5%. The SF-12 questionnaire showed a significantly reduced total score for physical and mental health compared to a general reference population.

Conclusions: The ASIF represents an innovative surgical procedure for the treatment of type C pelvic ring fractures. In the medium term, patient satisfaction was high and the complication rate was low, despite the small number of patients. More cases must be investigated before the procedure can be recommended in general, possibly replacing the external fixator for the treatment of pelvic ring fractures in the future.

Figures

Fig. 1

Arrangement of the anterior subcutaneous internal fixator (ASIF) in a synthetic pelvis bone. Bilateral screws are placed supraacetabular

Fig. 2

a A 41-year-old female patient. Postoperative radiograph of the pelvis shows posterior stabilisation of a bilateral transforaminal sacral fracture. Stabilisation of the bilateral anterior pelvic ring fracture was performed by anterior subcutaneous internal fixator (ASIF). b Same patient as Fig. 2a. Radiograph of the pelvis 41 months postoperatively. Worst case in this series with non-union and pelvic displacement after infection

Fig. 3

a A 58-year-old female patient. Postoperative radiograph of the pelvis shows posterior stabilisation of a transforaminal sacral fracture on the right side with screws, and the bilateral complete anterior pelvic ring fracture treated with anterior subcutaneous internal fixator (ASIF). b Same patient as Fig. 3a. Radiological outcome 21 months postoperatively. Excellent outcome in this series

Fig. 4

A 50-year-old female patient. Radiograph of the pelvis shows the device 58 months postoperatively. At the time of follow-up signs of implant loosening were not evident