eMedicine Specialties > Radiology > Musculoskeletal

Pelvis, Insufficiency Fractures

Wilfred CG Peh, MD, MBBS, FRCP(Glasg), FRCP(Edin), FRCR, Clinical Professor, Faculty of Medicine, National University of Singapore; Senior Consultant Radiologist, Alexandra Hospital, Singapore

Updated: Mar 25, 2009

Introduction

Background

Insufficiency fracture is a subgroup of stress fracture. Unlike the other subtype (ie, fatigue fracture), insufficiency fracture is caused by normal or physiologic stress upon weakened bone. Loss of bone trabeculae decreases the bone's elastic resistance.

Axial CT of the sacrum reveals fractures (arrows) in both sacral alae. Note the sclerosis of the adjacent bone.

Axial CT of the pubis reveals insufficiency fractures (arrows) in both parasymphyseal regions. Total hip replacement is an additional predisposing causative factor.

Presentation

Demographics

• Insufficiency fractures are estimated to occur in 1-5% of persons, depending on the referral population.
• Insufficiency fractures are estimated to occur in 1% of women older than 55 years.
• Insufficiency fractures predominantly affect women.
• Most patients with insufficiency fractures are older than 60 years.
• In various studies, the mean age ranges from 62-74 years.
• In most patients, insufficiency fractures resolve or improve significantly with conservative management.

The most common cause of insufficiency fracture is postmenopausal osteoporosis. Other important causes are senile osteoporosis, pelvic irradiation, corticosteroid therapy, and rheumatoid arthritis. Other reported causes are total hip replacement, Tarlov cyst, Paget disease, fibrous dysplasia, scurvy, osteopetrosis, primary biliary cirrhosis, lung transplantation, tabes dorsalis, vitamin D deficiency, and fluoride therapy.

Physical examination

Typically, patients present with groin pain, low back pain, or buttock pain and restricted hip movement. One quarter of patients have multiple sites of pain. In most patients, pain is severe enough to render the patient nonambulatory. Usually, patients present with either no history of trauma or a history of low impact trauma and signs of insufficiency fracture are nonspecific or nonexistent. Neurologic deficit is rare. In patients who have undergone pelvic irradiation, local soft tissue complications, especially affecting the rectum, frequently are encountered. Typically, a discordance exists between symptoms, which may be severe, and physical signs, which may be mild or absent.

Treatment

Management is conservative and consists initially of bed rest, reduced weight bearing, and the use of simple analgesics for pain relief. Graded exercises are started once symptomatic improvement is observed. Prognosis is good; healing is expected within 4 months.

Imaging-guided sacroplasty has been described for the treatment of sacral insufficiency fractures. Sacroplasty is a procedure in which polymethylacrylate, a quick-setting bone cement, is injected into the fracture. This technique appears to be useful in providing symptomatic relief to affected patients.^7,8

Preferred Examination

Clinical assessment does not provide a definitive diagnosis of insufficiency fracture. Imaging has an important role in the detection and diagnosis of insufficiency fractures of the pelvis.^9,10

Cabarrus et al compared the sensitivities of CT and MRI in detecting pelvic insufficiency fractures and found MRI to be substantially better in detecting such fractures. In patients undergoing both imaging modalities, 128 of 129 (99%) of fractures were detected by MRI, whereas only 89 of 129 fractures (69%) were detected by CT.¹¹

Bone scintigraphy and MRI are the imaging modalities of choice.^{12,13,14,15,16,17,11,18}

CT provides further definition of the fracture, especially if MRI is unavailable or bone scintigraphy is inconclusive.

Limitations of Techniques

• Bone scintigraphy: Bone scintigraphy relies on accurate interpretation of the uptake pattern. Bone scintigraphy is highly sensitive; however, atypical uptake patterns may be difficult to interpret. Abnormal uptake may persist for several months.
• CT: CT may not accurately detect fractures oriented transversely.
• MRI: MRI is sensitive for detection of fractures, soft tissue edema, and marrow changes. MRI may be better at demonstrating alternative diagnoses than bone scintigraphy or CT.

Differential Diagnoses

Bone Metastases

Radiography

Findings

Radiographic findings depend on the site of the fracture.

• Parasymphyseal and pubic ramus fractures may have an aggressive appearance, depending on the stage of fracture maturity.
• Findings include sclerosis, lytic fracture line, bone expansion, exuberant callus, and osteolysis (see Image 1).

Anteroposterior radiograph of the pelvis demonstrates areas of sclerosis in both sacral alae. Parasymphyseal fractures oriented vertically are seen as linear areas of osteolysis and adjacent sclerosis (arrows). Insufficiency fractures subsequently were confirmed on bone scans and CT.

• The most common finding is a sclerotic band or line.
• A lytic fracture line or cortical break rarely is observed.

Degree of Confidence

The degree of confidence is low. Sacral fractures are difficult to detect because of osteoporosis, overlying bowel gas, and calcified vessels.

False Positives/Negatives

Parasymphyseal and pubic ramus fractures often are mistaken for malignant lesions.

Sacral, iliac, and supra-acetabular fractures often are difficult to detect.

Computed Tomography

Axial CT of the sacrum reveals fractures (arrows) in both sacral alae. Note the sclerosis of the adjacent bone.

Coronal CT of the sacrum demonstrates fractures (arrows) in both sacral alae. These fractures are oriented parallel to the sacroiliac joints. Note the prominent adjacent sclerosis.

Axial CT of the pubis reveals insufficiency fractures (arrows) in both parasymphyseal regions. Total hip replacement is an additional predisposing causative factor.

Axial CT of the sacrum reveals 2 large Tarlov cysts (arrowheads) in the sacrum. The sacral insufficiency fractures produce anterior cortical breaks (arrows).

Findings

• On CT, sacral fractures typically are oriented vertically and are located parallel to the sacroiliac joints (see Image 2).
• A linear fracture line with surrounding sclerosis is observed (see Image 3).
• Pubic fractures are seen as a lytic fracture line often surrounded by callus (see Image 4).
• Typically, a soft tissue mass is absent, bone destruction is lacking, and adjacent fascial planes are preserved.
• CT also is useful for detecting large bony sacral defects such as Tarlov cysts (see Image 5) and for the diagnosis of coexisting malignant lesions.

Degree of Confidence

CT findings may be definitive for the diagnosis of insufficiency fractures of the pelvis. CT is specific and is useful as an alternative to MRI or bone scintigraphy when radiographs are inconclusive.

Magnetic Resonance Imaging

Axial T1-weighted MRI of the sacrum demonstrates decreased signal in the body and both alae of the sacrum. Bilateral sacral insufficiency fractures were confirmed by CT.

Axial T2-weighted MRI of the sacrum (same patient as in Image above) demonstrates linear bands of decreased signal in both sacral alae, parallel to the sacroiliac joints. Traces of fluid are observed within the fractures (small arrows). Adjacent edema is seen as areas of increased signal. Bilateral sacral insufficiency fractures were subsequently confirmed by CT.

Axial CT of the sacrum (same patient as in Image above) reveals insufficiency fractures in both sacral alae and the sacral body (arrows).

Findings

• MRI shows decreased signal on T1-weighted images and increased signal on T2-weighted images.
• In the sacrum, signal changes are seen as linear bands within the sacral ala and body; such bands are parallel to the sacroiliac joints (see Image 6).
• On T2-weighted images, the fracture line may be seen if it is surrounded by adjacent marrow edema (see Images 7-8).

Degree of Confidence

MRI is highly sensitive and highly specific. MRI cannot be used in patients with pacemakers — a significant limitation in the elderly population.

Nuclear Imaging

Bone scan of the pelvis reveals a butterfly-shaped area of uptake in the sacrum (arrows). Focal uptake in the pubis (arrowhead) corresponds to an associated parasymphyseal insufficiency fracture.

Bone scan of the pelvis reveals an incomplete (or partial) H-shaped area of uptake in the sacrum (arrows). Bilateral parasymphyseal insufficiency fractures (arrowheads) are present.

Bone scan of the pelvis demonstrates a horizontal linear dot pattern of uptake in the sacrum.

Bone scan of the pelvis demonstrates a linear area of uptake in the pubis (arrowheads). A concomitant H-shaped insufficiency fracture of the sacrum is observed.

Findings

• In nuclear studies, the typical H-shaped or butterfly pattern of uptake in the sacrum is diagnostic of insufficiency fracture. The vertical limbs of the H lie within the sacral ala, parallel to the sacroiliac joints; the transverse limb of the H extends across the sacral body (see Image 9).
• Other sacral variant uptake patterns occur frequently and include the unilateral ala, incomplete H (see Image 10), and horizontal linear dot (see Image 11) patterns.
• Iliac fractures are seen as linear areas of uptake.
• Pubic and supra-acetabular fractures produce areas of linear or focal uptake.
• Concomitant findings of 2 or more areas of uptake in the sacrum and at another pelvic site are considered diagnostic of insufficiency fractures of the pelvis (see Image 12).

Degree of Confidence

The degree of confidence may be high. Nuclear studies are highly sensitive and highly specific when a typical pattern of sacral uptake or concomitant sacral and pubic uptake is observed. If a typical pattern of abnormality is not present, the bone scan is much less specific.

False Positives/Negatives

For variant or incomplete patterns of uptake, the findings may be mistaken as signifying malignancy or other diseases. CT or MRI is useful in such cases.

Intervention

Medicolegal Pitfalls

• Failure to recognize insufficiency fractures of the pelvis may result in an incorrect diagnosis of malignancy. This may occur when areas of increased uptake are seen on bone scan or when marrow signal changes of the pelvis are observed on MRI, especially in patients who have undergone pelvic irradiation for gynecologic malignancies. Care should be taken to recognize the bone scan uptake pattern, particularly atypical patterns; on MRI, altered bone marrow signal in the sacrum is cause for suspicion.

Multimedia

Media file 1: Anteroposterior radiograph of the pelvis demonstrates areas of sclerosis in both sacral alae. Parasymphyseal fractures oriented vertically are seen as linear areas of osteolysis and adjacent sclerosis (arrows). Insufficiency fractures subsequently were confirmed on bone scans and CT.

Media file 2: Axial CT of the sacrum reveals fractures (arrows) in both sacral alae. Note the sclerosis of the adjacent bone.

Media file 3: Coronal CT of the sacrum demonstrates fractures (arrows) in both sacral alae. These fractures are oriented parallel to the sacroiliac joints. Note the prominent adjacent sclerosis.

Media file 4: Axial CT of the pubis reveals insufficiency fractures (arrows) in both parasymphyseal regions. Total hip replacement is an additional predisposing causative factor.

Media file 5: Axial CT of the sacrum reveals 2 large Tarlov cysts (arrowheads) in the sacrum. The sacral insufficiency fractures produce anterior cortical breaks (arrows).

Media file 6: Axial T1-weighted MRI of the sacrum demonstrates decreased signal in the body and both alae of the sacrum. Bilateral sacral insufficiency fractures were confirmed by CT.

Media file 7: Axial T2-weighted MRI of the sacrum (same patient as in Image above) demonstrates linear bands of decreased signal in both sacral alae, parallel to the sacroiliac joints. Traces of fluid are observed within the fractures (small arrows). Adjacent edema is seen as areas of increased signal. Bilateral sacral insufficiency fractures were subsequently confirmed by CT.

Media file 8: Axial CT of the sacrum (same patient as in Image above) reveals insufficiency fractures in both sacral alae and the sacral body (arrows).

Media file 9: Bone scan of the pelvis reveals a butterfly-shaped area of uptake in the sacrum (arrows). Focal uptake in the pubis (arrowhead) corresponds to an associated parasymphyseal insufficiency fracture.

Media file 10: Bone scan of the pelvis reveals an incomplete (or partial) H-shaped area of uptake in the sacrum (arrows). Bilateral parasymphyseal insufficiency fractures (arrowheads) are present.

Media file 11: Bone scan of the pelvis demonstrates a horizontal linear dot pattern of uptake in the sacrum.

Media file 12: Bone scan of the pelvis demonstrates a linear area of uptake in the pubis (arrowheads). A concomitant H-shaped insufficiency fracture of the sacrum is observed.

References

1. Davies AM, Bradley SA. Iliac insufficiency fractures. Br J Radiol. Apr 1991;64(760):305-9. [Medline].

2. Finiels H, Finiels PJ, Jacquot JM, Strubel D. [Fractures of the sacrum caused by bone insufficiency. Meta-analysis of 508 cases]. Presse Med. Nov 1 1997;26(33):1568-73. [Medline].

3. Gotis-Graham I, McGuigan L, Diamond T, et al. Sacral insufficiency fractures in the elderly. J Bone Joint Surg Br. Nov 1994;76(6):882-6. [Medline].

4. Peh WCG, Davies AM. Stress fractures. In: Davies AM, Johnson K, Whitehouse RW. Imaging of the hip and bony pelvis. Berlin: Springer; 2006:247-66.

5. Weber M, Hasler P, Gerber H. Insufficiency fractures of the sacrum. Twenty cases and review of the literature. Spine. Dec 1993;18(16):2507-12. [Medline].

6. Oh D, Huh SJ, Nam H, Park W, Han Y, Lim do H, et al. Pelvic insufficiency fracture after pelvic radiotherapy for cervical cancer: analysis of risk factors. Int J Radiat Oncol Biol Phys. Mar 15 2008;70(4):1183-8. [Medline].

7. Garant M. Sacroplasty: a new treatment for sacral insufficiency fracture. J Vasc Interv Radiol. Dec 2002;13(12):1265-7. [Medline].

8. Pommersheim W, Huang-Hellinger F, Baker M, Morris P. Sacroplasty: a treatment for sacral insufficiency fractures. AJNR Am J Neuroradiol. May 2003;24(5):1003-7. [Medline].

9. Peh WC, Khong PL, Yin Y, et al. Imaging of pelvic insufficiency fractures. Radiographics. Mar 1996;16(2):335-48. [Medline].

10. Campbell SE, Fajardo RS. Imaging of stress injuries of the pelvis. Semin Musculoskelet Radiol. Mar 2008;12(1):62-71. [Medline].

11. Cabarrus MC, Ambekar A, Lu Y, Link TM. MRI and CT of insufficiency fractures of the pelvis and the proximal femur. AJR Am J Roentgenol. Oct 2008;191(4):995-1001. [Medline].

12. Blomlie V, Lien HH, Iversen T, et al. Radiation-induced insufficiency fractures of the sacrum: evaluation with MR imaging. Radiology. Jul 1993;188(1):241-4. [Medline].

13. Blomlie V, Rofstad EK, Talle K, et al. Incidence of radiation-induced insufficiency fractures of the female pelvis: evaluation with MR imaging. AJR Am J Roentgenol. Nov 1996;167(5):1205-10. [Medline].

14. Gibbon WW, Hession PR. Diseases of the pubis and pubic symphysis: MR imaging appearances. AJR Am J Roentgenol. Sep 1997;169(3):849-53. [Medline].

15. Grangier C, Garcia J, Howarth NR, et al. Role of MRI in the diagnosis of insufficiency fractures of the sacrum and acetabular roof. Skeletal Radiol. Sep 1997;26(9):517-24. [Medline].

16. Hosono M, Kobayashi H, Fujimoto R, et al. MR appearance of parasymphseal insufficiency fractures of the os pubis. Skeletal Radiol. Sep 1997;26(9):525-8. [Medline].

17. Mammone JF, Schweitzer ME. MRI of occult sacral insufficiency fractures following radiotherapy. Skeletal Radiol. Feb 1995;24(2):101-4. [Medline].

18. Kwon JW, Huh SJ, Yoon YC, Choi SH, Jung JY, Oh D, et al. Pelvic bone complications after radiation therapy of uterine cervical cancer: evaluation with MRI. AJR Am J Roentgenol. Oct 2008;191(4):987-94. [Medline].

19. Adkins MC, Sundaram M. Radiologic case study. Insufficiency fracture of the acetabular roof in Paget''s disease. Orthopedics. Oct 2001;24(10):945, 1019-20. [Medline].

20. Albertsen AM, Egund N, Jurik AG, Jacobsen E. Posttraumatic osteolysis of the pubic bone simulating malignancy. Acta Radiol. Jan 1994;35(1):40-4. [Medline].

21. Angles F, Coscujuela A, Tramunt C, Gonzalez Panisello M, Portabella F. Complication of an insufficiency fracture of the acetabulum. Hip Int. Jul-Sep 2008;18(3):236-8. [Medline].

22. Blake SP, Connors AM. Sacral insufficiency fracture. Br J Radiol. Oct 2004;77(922):891-6. [Medline].

23. Christiansen CG, Kassim RA, Callaghan JJ, et al. Pubic ramus insufficiency fractures following total hip arthroplasty. A report of six cases. J Bone Joint Surg Am. Sep 2003;85-A(9):1819-22. [Medline].

24. Huh SJ, Kim B, Kang MK, et al. Pelvic insufficiency fracture after pelvic irradiation in uterine cervix cancer. Gynecol Oncol. Sep 2002;86(3):264-8. [Medline].

25. Karatas M, Basaran C, Ozgül E, Tarhan C, Agildere AM. Postpartum sacral stress fracture: an unusual case of low-back and buttock pain. Am J Phys Med Rehabil. May 2008;87(5):418-22. [Medline].

26. Mumber MP, Greven KM, Haygood TM. Pelvic insufficiency fractures associated with radiation atrophy: clinical recognition and diagnostic evaluation. Skeletal Radiol. Feb 1997;26(2):94-9. [Medline].

27. Ogino I, Okamoto N, Ono Y, et al. Pelvic insufficiency fractures in postmenopausal woman with advanced cervical cancer treated by radiotherapy. Radiother Oncol. Jul 2003;68(1):61-7. [Medline].

28. Oliver TB, Beggs I. Defects in the pelvic ring as a cause of sacral insufficiency fractures. Clin Radiol. Dec 1999;54(12):852-4. [Medline].

29. Peh WC. Intrafracture fluid: a new diagnostic sign of insufficiency fractures of the sacrum and ilium. Br J Radiol. Aug 2000;73(872):895-8. [Medline].

30. Peh WC, Cheng KC, Ho WY, Chan IK. Transient bone marrow oedema: a variant pattern of sacral insufficiency fractures. Australas Radiol. May 1998;42(2):102-5. [Medline].

31. Peh WC, Evans NS. Tarlov cysts--another cause of sacral insufficiency fractures?. Clin Radiol. Nov 1992;46(5):329-30. [Medline].

32. Peh WC, Gough AK, Sheeran T, et al. Pelvic insufficiency fractures in rheumatoid arthritis. Br J Rheumatol. Apr 1993;32(4):319-24. [Medline].

33. Peh WC, Khong PL, Ho WY. Case report: sacral insufficiency fractures masking malignancy. Clin Radiol. Jan 1997;52(1):71-2. [Medline].

34. Peh WC, Khong PL, Ho WY, et al. Sacral insufficiency fractures. Spectrum of radiological features. Clin Imaging. Apr-Jun 1995;19(2):92-101. [Medline].

35. Peh WC, Khong PL, Sham JS, et al. Sacral and pubic insufficiency fractures after irradiation of gynaecological malignancies. Clin Oncol (R Coll Radiol). 1995;7(2):117-22. [Medline].

36. Peh WC, Ooi GC. Vacuum phenomena in the sacroiliac joints and in association with sacral insufficiency fractures. Incidence and significance. Spine. Sep 1 1997;22(17):2005-8. [Medline].

Keywords

pelvis insufficiency fracture, pelvis fracture, pelvic fracture, fracture of pelvis, stress fracture, pubic bone, parasymphysis, pubic rami, unstable pelvic fracture

Contributor Information and Disclosures

Author

Wilfred CG Peh, MD, MBBS, FRCP(Glasg), FRCP(Edin), FRCR, Clinical Professor, Faculty of Medicine, National University of Singapore; Senior Consultant Radiologist, Alexandra Hospital, Singapore
Wilfred CG Peh, MD, MBBS, FRCP(Glasg), FRCP(Edin), FRCR is a member of the following medical societies: American Roentgen Ray Society, British Institute of Radiology, International Skeletal Society, Radiological Society of North America, Royal College of Physicians, and Royal College of Radiologists
Disclosure: Nothing to disclose.

Medical Editor

Leon Lenchik, MD, Director, Densitometry Minifellowship, Assistant Professor, Department of Radiology, Wake Forest University Medical Center
Leon Lenchik, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, and Radiological Society of North America
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

William R Reinus, MD, MBA, FACR, Professor of Radiology, Temple University; Chief of Musculoskeletal and Trauma Radiology, Vice Chair, Department of Radiology, Temple University Hospital
William R Reinus, MD, MBA, FACR is a member of the following medical societies: Alpha Omega Alpha, American College of Radiology, American Roentgen Ray Society, Radiological Society of North America, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington
Felix S Chew, MD, MBA, EdM is a member of the following medical societies: American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

Related eMedicine topics

Ultrasonography, Pelvic

Fracture, Pelvic

Pelvic Fractures

Unstable Pelvic Fractures

Pelvic Ring Fractures

© 1994- by Medscape.
All Rights Reserved
(http://www.medscape.com/public/copyright)