Sacral insufficiency

DIAGNOSIS

Sacral insufficiency

IMAGING FINDINGS

During the hospitalization, the patient’s anticoagulation was switched from warfarin to heparin. The heparin was discontinued on the morning of the procedure. She arrived in the radiology department by stretcher and was subsequently placed in the prone position on the computed tomography (CT) table. Conscious sedation was achieved with intravenous Versed (Hoffmann-La Roche Inc., Nutley, NJ) and fentanyl, and her vital signs were monitored by the radiology nursing staff. Thin-section axial images of the pelvis were obtained, and the sites of sacral fracture and severe osteopenia were identified. Local anesthesia was obtained with 1% lidocaine infiltration. Using the “CT fluoroscopy” package available on a Somatom Plus 4 helical CT scanner (Siemens Medical Solutions USA, Inc., Malvern, PA), three 13-gauge trocar needles (Parallax Medical, Inc./ArthroCare, Sunnyvale, CA) were placed into the sacrum. Two of the needles were placed into the right sacrum, corresponding to the bone scan findings, and a single needle was placed on the left. CT fluoroscopic guidance permitted nearly “real-time” positioning of the trocar needle within the marrow cavity of the sacrum, midway between the sacroiliac joint and the sacral foramina (Figure 2).

The patient was transferred in the prone position via stretcher to the angiography suite, where the remainder of the procedure was performed using single-plane fluoroscopy (Figure 3). With the knowledge of the precise needle location provided by the CT, there was no need for venography and biplane fluoroscopy during cement injection in this patient. In a fashion similar to that used for vertebroplasty,³ polymethyl methacrylate (PMMA) was mixed with sterile barium (Tracers, Parallax Medical/ArthroCare) and injected through the in-dwelling trocar needles. Under fluoroscopy, approximately 7 mL of the PMMA solution was placed through the 2 right-sided trocar needles and approximately 4 mL was placed through the single left trocar needle. As shown in Figure 4, PMMA filled the marrow space in the expected trabecular pattern. Because of the patient’s previous aortic valve replacement, 1 g of Kefzol (Eli Lilly and Co., Indianapolis, IN) was administered intravenously during the procedure.

Following the procedure, a CT scan of the pelvis confirmed the appropriate placement of the PMMA solution within the marrow space of the sacrum (Figure 5). A tiny drop of PMMA was seen extending into the left sacral foramen without any clinical sequela (Figure 5). The patient was then returned to her hospital bed and maintained the supine position for a 4-hour recovery period, which allowed the PMMA mixture to coalesce. The patient reported a modest relief of pain the evening following the procedure and she was able to ambulate with assistance.

At a 2-week follow-up visit, the pain in her pelvis had completely resolved and she was able to ambulate without assistance. She continues to take anti-inflammatory analgesics for unrelated arthritic conditions.

DISCUSSION

There has been a recent increase in the use of percutaneous vertebroplasty for the treatment of compression fractures of various causes. Osteoporosis is a major cause of painful vertebral compression fractures. This technique has been shown to lessen or alleviate pain and to provide vertebral stabilization, allowing patients to mobilize more quickly than they can following medical therapy alone.¹

Sacral insufficiency fractures are often seen in a similar patient population as vertebral compression fractures, most commonly postmenopausal women with osteoporosis. Additional risk factors include rheumatoid arthritis, steroid therapy, previous hip replacement, and radiation therapy to the pelvis.² Sacral insufficiency fractures are often associated with severe, debilitating pain. Most sacral insufficiency fractures eventually heal with time; current medical therapy consists of bed rest and pain management.² However, percutaneous sacroplasty, a variation of percutaneous vertebroplasty, is an alternative that may provide symptomatic relief and shorten recovery time. Using techniques modified from vertebroplasty experience, sacroplasty has been described as a successful alternative to traditional medical therapy for the treatment of sacral insufficiency fractures.^3,4

Percutaneous sacroplasty offers an attractive alternative to traditional medical therapy for sacral insufficiency fractures. There have been limited case reports/series published regarding sacroplasty,^3,4 with (to our knowledge) only 1 previous description of sacroplasty performed utilizing CT guidance.⁴ As in the previously reported cases,^3,4 we believe that accurate needle placement within the sacrum can be challenging under fluoroscopic guidance. Additionally, the sacral foramina may be difficult to visualize under fluoroscopy. In our experience, the axial images provide improved visualization of the sacral foramen and the sacroiliac joints, which permits more precise needle placement. Also, with CT fluoroscopy, needle depth and trajectory into the marrow cavity is easily determined and manipulated. Improved visualization should reduce the risk of inappropriate needle placement into the sacral foramen, the sacroiliac joints, or adjacent soft tissues. The precise needle placement afforded by CT guidance may also eliminate the need for confirmatory venography. CT guidance may also enhance operator confidence during the procedure and permit extrusion of larger volumes of PMMA into the sacrum, potentially improving clinical outcome.

CONCLUSION

The use of CT guidance and CT fluoroscopy during percutaneous sacroplasty only increases its value as a therapeutic option. In our experience, CT fluoroscopy combined with conventional fluoroscopy allowed for more precise placement of trocar needles than would conventional fluoroscopy alone, with a potentially improved clinical outcome.

REFERENCES

1. Jensen ME. Percurtaneous vertebroplasty: A new therapy for treatment of painful vertebral body compression fractures. ApplRadiol. 2000;29(6):7-11.
2. De Smet AA, Neff JR. Pubic and sacral insufficiency fractures: Clinical course and radiologic findings. AJR Am J Roentgenol. 1985;145:601-606.
3. Garant M. Sacroplasty: A new treatment for sacral insufficiency fracture. J Vasc Interv Radiol. 2002;13:1265-1267.
4. Pommersheim W, Huang-Hellinger F, Baker M, Morris P. Sacroplasty: A treatment for sacral insufficiency fractures. AJNR Am J Neuroradiol. 2003;24:1003-1007.