Biomechanical comparison of sacroiliac screw techniques for unstable pelvic ring fractures.

OBJECTIVE: To determine the stiffness and strength of various sacroiliac screw fixations to compare different sacroiliac screw techniques. DESIGN: Randomized comparative study on embalmed human pelvises. MATERIALS AND METHODS: In 12 specimens, we created a symphysiolysis and sacral fractures on both sides. Each of these 24 sacral fractures was fixed with 1 of the following methods: 1 sacroiliac screw in the vertebral body of S1, 2 screws convergingly in S1, or 1 screw in S1 and 1 in S2. On the left and right side of a pelvis, different techniques were used. The pubic symphysis was not stabilized. We measured the translation and rotation stiffness of the fixations and the load to failure using a 3-dimensional video system. RESULTS: The stiffness of the intact posterior pelvic ring was superior to any screw technique. Significant differences were found for the load to failure and rotation stiffness between the techniques with 2 screws and a single screw in S1. The techniques utilizing 2 screws showed no differences. CONCLUSIONS: Based on the results of this study, we can conclude that a second sacroiliac screw in completely unstable pelvic fractures increases rotation stiffness and improves the load to failure.

Functional outcome of internal fixation for pelvic ring fractures.

OBJECTIVE: Evaluation of the functional outcome after unstable pelvic ring fractures stabilized with internal fixation. METHODS: Between January 1, 1990, and September 1, 1997, 37 patients were treated with internal fixation for unstable pelvic fracture. Demographic data, type of accident, Hospital Trauma Index-Injury Severity Score, and fracture type according to Tile classification were scored. One patient died the day after the accident from neurologic injury. A Short Form-36 health questionnaire and a form regarding functional result after pelvic trauma, adapted from Majeed et al., were returned by 31 of 36 patients (86%). Twenty-eight patients (78%) were seen for physical and radiologic examination. RESULTS: Twenty-six men and 11 women, with an average age of 34.7 years (range, 15-66 years) were included. The mean Injury Severity Score reached 30.4 (range, 16-66). According to the Tile classification, there were 16 type B fractures and 21 type C fractures. Seven patients were treated with open reduction and internal fixation of the pubic arch, 10 patients were treated with a combination of anterior open reduction and internal fixation with additional external fixation to increase the stability of the posterior ring. Nineteen patients underwent internal fixation of both anterior and posterior arch. In the remaining case, percutaneous posterior screw fixation was combined with anterior external fixation, because of estimated infectious risk. The average follow-up time was 35.6 months. Patients scored 78.6 of 100 on the Majeed score. Remarkable was the reported change in sexual intercourse in 12 patients (40%). Only 12 patients (40%) did not have complaints when sitting. On the SF-36 scales physical and social functioning, role limitations due to physical problems and vitality were limited compared with the averages for the Dutch population. Patients treated with combined anterior and posterior internal fixation scored significantly better on both the Majeed score and on the categories physical functioning, pain, general health and social functioning compared with patients with similar fractures treated with a combination of anterior internal fixation with external fixation. At the physical examination, 11 of 28 patients (39%) did not have any abnormality. Nineteen patients (68%) were back at their original job, which was physically demanding in 9 cases. There was a suspicion of nonunion of the posterior arch in two patients, which could be confirmed with a computed tomographic scan. CONCLUSION: In general, limitations in functioning are reported, even after long-term follow-up. In partially unstable fractures, solitary anterior fixation gives good results. In completely unstable fractures, patients treated with combined internal fixation anterior as well as posterior scored a better outcome compared with combined internal and external fixation. Therefore, this technique is recommended as treatment of first choice in completely unstable fractures.