Session I - Pelvis

Clinical Experience with 591 Sacral Fractures

Axel Gänsslen, MD; Stefan Zech, MD; Tobias Hüfner, MD;Tim Pohlemann, Prof., MD, Hannover Medical School, Hannover, Germany

Purpose: Interest in fractures of the sacrum increased over the last years because the rate of detected fractures increased. Additional injuries (e.g. nerve deficits) were diagnosed more frequently, and stabilization techniques became more popular. The purpose of this study was the evaluation of our clinical experience in treating these injuries with special regards to the additional neurological injury.

Methods: Between January 1, 1972 and December 31, 1998, 1,800 patients with pelvic ring fractures were treated at our institution. Within this group, 591 patients sustained a sacral fracture as part of their pelvic ring injury. Evaluation consisted of demographic data, mechanism of injury, Injury Severity Score (ISS), type of pelvic fracture, neurological evaluation and type of treatment.

Results: There were 306 male and 285 female patients, ranging in age >from 3 to 91 years. In the majority of cases the mechanism of injury was a motor vehicle accident (58%), a pedestrian injury (12%) or a fall in 26% (154). The mean ISS was 21.7 points (3-75). There were 40 type 61-A, 307 type 61-B and 244 61-C fractures. Of the 40 patients with A-type fractures 27 had a transverse fracture below S2, two of them with a persistent conus cauda syndrome requiring nerve root decompression. Ten patients had a coccyx-fracture and three had a sacrococcygeal dislocation. Of the patients with B-type injuries, 11 had an open book injury (61-B1, 61 B3.1) and 296 had a lateral compression injury (61-B2, 61 B3.2, 61-B3.3). In 6 cases a sacral fracture-related nerve injury was present (2%); in 15 cases the neurological status was unknown because of a polytrauma situation.

Patients with unstable sacral fractures (n = 244) had a unilateral unstable sacral fracture in 86% of the cases and a bilateral unstable sacral fracture in 14%. Nerve injuries were present in 56 cases; a neurological evaluation was impossible for 33 patients because of additional head injury or a polytrauma situation.

The overall rate of sacral fracture-related nerve deficits was 12%. The presence of a sacral fracture-related nerve deficit was correlated with the instability of the pelvic injury. After A-type fractures, sacral plexus injury was seen in 5% (2 patients with displaced transverse fractures and nerve root avulsion), and in 2% after B-type fractures (in a further 3% the lumbosacral nerve injury was related to an additional spine or acetabular fracture). After C-type fractures of the sacrum, the rate of nerve injury increased to 26%. Additionally, there was an increase of sacrum-related nerve deficits according to the localization of sacral fractures. Trans-alar fractures had an overall rate of nerve injury of 3.8%. After transforaminal fractures there was an increase to 10.7%, whereas after central fractures only 4.5% had a nerve deficit. In bilateral sacral fracture the rate further increased to 23%, the highest rate was observed after "suicidal jumper´fractures" (H-type fractures) with 88% (15/17). In the C-type fracture group there was a strong correlation between primary sacral fracture displacement and the rate of nerve injury. A posterior displacement of >5mm was associated with an increase of nerve deficits (35% vs. 15%).

The majority of patients were treated nonoperatively. In 72% of the fractures an open/closed reduction and internal fixation was performed. In A-type fractures 2 patients had a sacral nerve root decompression with stabilization of their transverse fracture, in one case a sacrococcygeal dislocation was stabilized with sutures. No sacral B-type fractures were stabilized; 69 of the C-type fractures were stabilized (28%) in 12 cases with closed techniques (transiliosacral screw fixation, sacral bars) and in 57 cases with ORIF-techniques. Overall, the mortality rate was 15.4%.

Discussion and Conclusion: Sacral fractures are present in nearly one-third of all pelvic ring injuries and are accompanied with a relatively high rate of additional neurological injuries. Primary risk factors for a sacral fracture-related nerve deficit were the instability of the pelvic injury (highest rates after C-type injuries), the sacral fracture displacement (>5mm) and the type of sacral fracture (highest rate after bilateral sacral fractures).