Sports Medicine Update

Evaluation and Management of Stress Fractures of the Pelvis and Sacrum

Robert G. Hosey, MD; Marifel Mitzi F. Fernandez, MD; Darren L. Johnson, MD

  • Orthopedics
  • April 2008 - Volume 31 · Issue 4:
  • DOI:
Most stress fractures of the pelvis and sacrum can be treated nonoperatively with activity modification and thorough assessment of training activities and nutritional factors.

It is important to have knowledge of proper training techniques and adequate nutrition for the prevention of overuse injuries. Overuse injuries occur both in the competitive and recreational (“weekend-warrior”) athlete. Stress fractures in athletes are thought to develop mostly by repetitive microtrauma and fatigue failure of the bone caused by increases in activity (fatigue fractures).1 In certain populations, (eg, the female triad) stress fractures are a result of an inadequate remodeling response to normal stresses placed on bony tissue (insufficiency fractures).1

Stress fractures of the pelvis and sacrum are less common than lower extremity stress fractures. They are considered low-risk stress fractures2 and have been reported mainly in long-distance runners and female military recruits.3-5 This article provides a better understanding of risk factors and presentation of these injuries and rehabilitation and prevention strategies.

Epidemiology

Stress fractures are commonly encountered problem in sports medicine. They account for a significant percentage of overuse injuries and up to 15% of injuries in runners. The majority of stress fractures occur in the lower extremity with stress fractures of the tibia, metatarsals, and fibula being the most commonly reported in the literature.6 Stress fractures of the pelvis are significantly less common accounting for 1% to 7% of reported stress fractures.6 Certain patient populations, however, may incur pelvic bone stress injuries at a significantly higher rate. For example, pelvic bone stress injuries account for approximately 4% stress fractures in track and field athletes.7 Female military recruits have the highest reported incidence at 22% of all stress fractures.5

Etiology

The specific etiology of pelvic stress fractures and bone stress injuries in general is not well delineated. While multiple factors, both intrinsic and extrinsic, play a role in the evolution of bone stress injury, repetitive loading to the axial skeleton, resulting from ground reaction forces and muscle contraction is inherent to these injuries.8 Females have historically had a greater risk for development of stress fractures. Pelvic stress fractures seem to predominately affect females. Bennell et al8 found pelvic stress fractures only in female track and field athletes, mostly mid-distance and long-distance runners. Participants in this study had an average BMI of 21, were 20 years on average, and were running 40 to 53 km/wk (25-33 miles/wk). Low level of aerobic fitness prior to starting training has been found to be a cause of pelvic stress injuries in female military recruits.5 In both collegiate and military studies, a history of amenorrhea has been found to be a risk factor for stress fractures in general.5,9,10 This may be due to direct effect of decreased estrogen on bone and subsequently low bone mineral density.11 A history of previous stress fractures may also be a risk factor in the development of recurrent episodes.11

History and Physical Examination Findings

A thorough clinical history and physical examination are essential in the diagnosis of sacral and pelvic stress injuries. In the history, it is important to ask about any increase in repetitive weight-bearing activities, change to a more intensive training regimen,1,3,4,12,13 trauma, previous injuries, and past medical history of metabolic and rheumatologic diseases. Patients should also be asked about any previous history of stress fractures. There have been extensive studies in the literature about the female triad (amenorrhea, disordered eating, and osteopenia/osteoporosis)9,10 and the increased association to the development of stress fractures.9 This should be an important consideration in the evaluation of the female athlete, with regards to menstrual history and screening for nutritional deficiencies.9

In pubic symphysis stress injuries, patients report chronic pain in the symphysis pubis or groin area exacerbated by any type of running activity or kicking.11,14,15 Some men report abdominal pain, scrotal pain or perineal pain. The rectus abdominis muscle, adductors and gracilis muscles are thought to contribute to the development of this injury.3,12,14 There is direct tenderness over the pubic symphysis and over the insertion of the adductors on physical examination.12,14

Sacral stress fractures are more common in females and long distance runners with an insidious onset of asymmetric low back pain or gluteal pain.4,5 Pain in the hip, groin, pelvis and/or lumbar radicular or sciatica-type14 symptoms have been reported. On examination, there is tenderness on palpation over the sacroiliac joint of the affected side and a painful range of motion.16 There may also be a positive FABER test (flexion, abduction, external rotation of the ipsilateral hip) and positive flamingo test,3 which is pain when standing on one leg at the affected side.

Stress fractures of the pubic rami have been reported in long-distance runners, mostly in females. Patients report a history of insidious onset pain over the groin, perineal region, buttock or thigh.12,13 Patients may have a noticeable limp with walking. There is direct tenderness over the pubic ramus, with normal or decreased hip range of motion.13

A neurologic examination should also be included to rule out any lumbosacral nerve root involvement in any of the above mentioned injuries.

Imaging

For patients with suspected pelvic or sacral stress reactions/fractures, radiographs of the pelvis (AP, oblique, and outlet views) should be obtained initially. Early radiographic changes may show a faint radiolucency of the cortex or periosteal reactions in the later stages.17 Repeat radiographs after at least 2 weeks of rest may show evidence of bone healing with callus formation. These changes usually are subtle and diagnosis by plain radiographs difficult. This is especially difficult in the pelvis and sacrum because the presence of bowel gas may obscure the bony structures. In pubic symphysis stress injuries, plain radiographs may show sclerosis or erosion of the symphysis.14

In cases where there is a high index of suspicion for pelvic bone stress injuries by clinical history and physical examination, further imaging is recommended. Magnetic resonance imaging (MRI) is often the diagnostic procedure of choice because of its’ high sensitivity and specificity for detecting stress fractures. Magnetic resonance imaging typically is able to demonstrate a spectrum of injury ranging from soft tissue swelling, cortical and medullary bony edema, and the presence or absence of a distinct fracture line (Figures 1, 2 ).17 As a result, MRI can be particularly helpful in the staging of stress fractures. However, there have been published reports that MRI changes may not be definitive in the early stages of the injury.7

Figure 1A: Sacral stress fracture. MRI of a 21-year-old female swimmer with low back pain from dry land training shows a distinct fracture line with surrounding bony edema of the sacral alae
Figure 1B: Sacral stress fracture. MRI of a 21-year-old female swimmer with low back pain from dry land training shows a distinct fracture line with surrounding bony edema of the sacral alae
Figure 2: Pubic rami stress fracture. MRI of a 35-year-old female recreational runner with ischial/gluteal pain during running activity shows a fracture line and edema of the bone and surrounding soft tissue.
Figure 1: Sacral stress fracture. MRI of a 21-year-old female swimmer with low back pain from dry land training shows a distinct fracture line with surrounding bony edema of the sacral alae. Figure 2: Pubic rami stress fracture. MRI of a 35-year-old female recreational runner with ischial/gluteal pain during running activity shows a fracture line and edema of the bone and surrounding soft tissue.

Nuclear scintigraphy or bone scans may also be used to evaluate stress fractures. Increased radiotracer uptake is seen in areas with stress reactions/fractures.17 However, bone scans are not very specific for fractures. Increased uptake is also seen with infection, tumors, trauma or metabolic bone diseases. Patients are also subjected to prolonged testing times and exposure to radiation.

Computed tomography (CT) scans are not routinely used for evaluation of stress reactions/fractures of the pelvis or sacrum. Single photon emission CT scans have been used to localize stress fractures in the pelvis and sacrum. This would involve nuclear imaging and radiation, with the specific disadvantages discussed earlier.

Differential Diagnosis

  • Muscle injuries—including adductor strain, piriformis syndrome, etc.
  • Lumbar disk disease/spinal stenosis for sacral stress fractures.
  • Spondylolisthesis or spondylolysis for sacral stress fractures.
  • Tumors.
  • Infection/osteomyelitis.
  • Metabolic bone disorders.
  • Referred pain from gastrointestinal or genitourinary tract.

Management

Medications such as nonsteroidal anti-inflammatory agents, acetaminophen, or in severe cases opioid analgesics, may be used in the short term for pain control. In female athletes with a history suggestive of the female triad, oral contraceptive pills may be used to address the amenorrhea.

Additional Work-up

In a patient with suspected pelvic stress injury and a history suggestive of metabolic bone disorders, the following laboratory tests may be useful9:

  • CBC,
  • TSH,
  • Basic metabolic panel, calcium, phosphate, alkaline phosphatase,
  • Liver function tests,
  • PTH,
  • Vitamin D level,
  • Serum and urine electrophoresis, and
  • Dexa scan.

Nutritional assessment and evaluation of the athlete’s training regimen and equipment should also be done to address the possible factors contributing to the development of the stress fractures.

Rehabilitation and Return to Play Guidelines

The general principles of treatment for stress fractures apply to stress fractures of the pelvis and sacrum. The treatment plan should be tailored to the athlete for optimum recovery and return to play.18,19

Relative rest and avoidance of painful activity is the initial step.12,18 In some cases of sacral stress fractures, patient may need to be nonweight bearing for a few days to weeks. The use of crutches may be discontinued where there is no more pain with ambulation. Activity modification should aim to decrease impact loading of the affected bone. Cross-training by biking or swimming may be allowed after 1 to 2 weeks with no symptoms, to avoid deconditioning. Physical therapy can then be initiated, which would include a core and hip strengthening program. The athlete would then be allowed to a gradual increase in activity, if pain-free. Total rehabilitation time for optimum healing and return to activity may take upwards of 4 to 8 weeks.18

Conclusion

The diagnosis of pelvic and sacral stress injuries/fractures is difficult. Decisions on diagnostic work-up and treatment plans are made based on an increased index of suspicion. It is inherent to any athlete to aim for excellence in their sport. It is important to have knowledge of proper training techniques and adequate nutrition for the prevention of overuse injuries. This should translate not only to the athlete, but also to the coaches, athletic training staff and support staff.

References

  1. Pepper M, Akuthota V, McCarty EC. The pathophysiology of stress fractures. Clin Sports Med. 2006; 25(1):1-16.
  2. Boden BP, Osbahr DC, Jimenez C. Low-risk stress fractures. Am J Sports Med. 2001; 29(1):100-111.
  3. Bono CM. Low-back pain in athletes. J Bone Joint Surg Am. 2004; 86(2):382-396.
  4. Kelly EW, Jonson SR, Cohen ME, Shaffer R. Stress fractures of the pelvis in female navy recruits: an analysis of possible mechanisms of injury. Mil Med. 2000; 165(2):142-146.
  5. Shaffer RA, Rauh MJ, Brodine SK, Trone DW, Macera CA. Predictors of stress fracture susceptibility in young recruits. Am J Sports Med. 2006; 34(1):108-114.
  6. Snyder RA, Koester MC, Dunn WR. Epidemiology of stress fractures. Clin Sports Med. 2006; 25(1):37-52.
  7. Bennell KL, Malcolm SA, Thomas SA, Wark JD, Brukner PD. The incidence and distribution of stress fractures in competitive track and field athletes. A twelve month prospective study. Am J Sports Med. 1996; 24(2):211-217.
  8. Lin JT, Lane JM. Sacral stress fractures. J Women’s Health (Larchmt). 2003; 12(9):879-888.
  9. Yeager KK, Agostini R, Nattiv A, Drinkwater B. The female athlete triad: disordered eating, amenorrhea, osteoporosis. Med Sci Sports Exer. 1993; 25(7):775-777.
  10. Kelsey JL, Bachrach LK, Procter-Gray E, et al. Risk factor for stress fracture among young female cross-country runners. Med Sci Sports Exerc. 2007; 29(9):1457-1463.
  11. Miller C, Major N, Toth A. Pelvic stress injuries in the athlete. Management and prevention. Sports Med. 2003; 33(13):1003-1012
  12. Pavlov H, Nelson TL, Warren RF, Torg JS, Burstein AH. Stress fractures of the pubic ramus. A report of twelve cases. J Bone Joint Surg Am. 1982; 64(7):1020-1025.
  13. Major NM, Helms CA. Pelvic stress injuries: the relationship between osteitis pubis (symphysis pubis stress injury) and sacroiliac abnormalities in athletes. Skeletal Radiol. 1997; 26(12):711-717.
  14. Fricker PA, Taunton JE, Ammann W. Osteitis pubis in athletes: infection, inflammation or injury? Sports Medicine. 1991; 12(4):266-279.
  15. Johnson AW, Weiss CB Jr, Stento K, Wheeler DL. Stress fractures of the sacrum. An atypical cause of low back pain in the female athlete. Am J Sports Med. 2001; 29(4):498-508.
  16. Sofka CM. Imaging of stress fractures. Clin Sports Med. 2006; 25:53-62.
  17. Fredericson M, Moore W, Biswal S. Sacral stress fractures: magnetic resonance imaging not always definitive for early stage injuries: a report of 2 cases. Am J Sports Med. 2007; 35(5):835-839.
  18. Raasch WG, Hergan DJ. Treatment of stress fractures: the fundamentals. Clin Sports Med. 2006; 25(1): 29-36.
  19. Diehl JJ, Best TM, Kaeding CC. Classification and return to play considerations for stress fractures. Clin Sports Med. 2006; 25(1):17-28.

Authors

Drs Hosey, Fernandez, and Johnson are from the Department of Orthopedics and Sports Medicine, University of Kentucky, Lexington, Kentucky.

Drs Hosey, Fernandez, and Johnson have no relevant financial relationships to disclose.

Correspondence should be addressed to: Robert G. Hosey, MD, University of Kentucky Chandler Medical Center, K 433 Kentucky Clinic, 740 S Limestone, Lexington, KY 40536-0284.

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