THE USE OF MR IMAGING IN THE ASSESSMENT AND CLINICAL MANAGEMENT OF STRESS REACTIONS OF BONE IN HIGH-PERFORMANCE ATHLETES

https://doi.org/10.1016/S0278-5919(05)70023-5Get rights and content

Bone is a dynamic tissue, and its functional mass remodels in predictable patterns in response to external stress, as suggested by Wolff.14a Historically, stress fractures have been defined primarily as a result of a healing response of bone. This bone response is seen on traditional radiographic images. Using this form of imaging, a stress fracture is not identified until a lesion has progressed to an intercortical fracture with extension to the periosteum, resulting either in periosteal changes or as a frank fracture through the cortex itself; however, there is currently increased recognition that a stress fracture is the end result of a continuum of biological reaction of a bone to external stress. This biologic response can alter the balance between normal repair and the remodeling process, which results in the temporary disturbance in the equilibrium between bone reabsorption and bone regeneration.

If one views stress phenomenon of bone as a continuum, then diagnostic tests to help elucidate the earlier stages of stress reaction would be useful to the clinician. Indeed, with the advent of newer techniques to investigate stress fractures, each new imaging modality has increased appreciation of this continuum and the mechanisms and responses involved with stress injury; however, the usefulness of any grading system is only useful if it relates to increasing accuracy in defining the clinical picture, which in turn directly relates to the clinical management of an individual case.

Radiologic studies of stress fractures using conventional radiographs reveal a range of relatively late skeletal responses from periosteal reactions and endosteal sclerosis to frank fractures. With the advent of scintigraphy, it became apparent that increasing isotope intake could be seen in symptomatic sites in the absence of plain radiographic findings in 20% to 40% of patients.12

Although not generally known to orthopedists, Roub et al,12 and Floyd et al,5 proposed a gradation of radionuclide findings ranging from occult stress reaction to frank stress fractures. This concept was refined and eventually correlated with clinical findings by Chisin4 and Zwas15 for the assessment of stress injury, particularly to the long bones of the legs. On the other hand, computed tomography (CT) scanning, although able to demonstrate subtle callus and fracture lines, had little to offer except in assessment of the tarsal navicular and for established stress fractures. With the advent of MR imaging, understanding of stress fractures and stress phenomena of bone has increased dramatically, and focus has begun more on the bone marrow abnormalities that can be seen on MR images following repetitive trauma.

Section snippets

HISTOLOGIC GRADING OF STRESS FRACTURES AND THE INTRODUCTION OF AN IMAGING GRADING SYSTEM

As long ago as 1963, Johnson et al8 described the histogenesis of tibial stress fractures of various age. During the first week there was active osteoclastic resorption of the cortex, but decalcification, microfracture, microcallus, and osteocyte death was not apparent. During the second week, endosteal (and occasionally periosteal) callus formation was present. Johnson found that if the inciting activity was discontinued at this time, no actual fracture occurred. On the other hand, if the

THE MR GRADING OF STRESS PHENOMENA AND STRESS FRACTURES

It became obvious that MR imaging was not only just as sensitive in demonstrating early stress changes to bone, but was more specific than scintigraphy. Five years ago the authors proposed a similar MR grading system (Table 2). There are several MR sequences to demonstrate subtle marrow changes, and most of these depend on fat suppression. They go under a number of acronyms, which include FLASH (Fast, Low- Angle SHot), FISP (Fast Imaging Steady-state Precession), and STIR (Short Tau Inversion R

DIFFERENTIAL DIAGNOSIS OF STRESS FRACTURES ON MR IMAGING

Given the correct clinical setting, the diagnosis of stress fracture or stress injury is usually easy to substantiate; however, many different diseases and conditions can give rise to high signal on delayed T2, and, particularly, on fat-suppression sequences. Increased intramedullary signal on these delayed sequences represents early bone hemorrhage, marrow edema, or fluid, and can be seen in such things as early infection and in some early tumours, particularly those involving the marrow, such

EVERYDAY USE OF MR IMAGING IN THE ASSESSMENT OF INJURY IN ATHLETES

With the introduction of MR imaging, attention has begun to focus on abnormalities in the bone marrow signal as well as in the surrounding soft tissues. Initial reports described a broad band of altered signal in the marrow, containing a narrow fracture line and increased signal in the periosteum, which was thought to be characteristic of a stress fracture. A number of isolated case reports and small series have also confirmed these findings, but have also suggested a second, more amorphous

CLINICAL MANAGEMENT

Treatment of stress fractures using a classification system is predicated on the belief that bone follows predictable responses to external stress. If those external stresses increase, the pattern of bone biologic response continues. If the external stress is diminished or removed, a predictable pattern of bone healing will ensue.

A grading system and a standard treatment of lower extremity stress fractures have been used at the University of Minnesota since 1990 (this treatment protocol will be

THE CLINICAL USEFULNESS OF THE MR GRADING SYSTEM

The primary benefit of using the MR classification system as opposed to a bone scintigraphy grading system is its ease of use. It involves less time and no radiation. MR classification categories are more readily defined and understood by the radiologist and the clinician; however, MR imaging has additional usefulness to the clinician and to the athlete.

MR imaging also has the ability to define the duration of the injury to some extent. With bone scanning, it is difficult to determine the age

AT-RISK FRACTURES

The concept of at-risk fractures takes precedence over the aggressive approach to sport reentry as described previously. If the location of the lesion is in a critical anatomic site, consideration for the seriousness of a complete fracture has to be considered in regards to the aggressiveness of the treatment program. These fractures might include a long bone fracture with an intra-articular extension, a femoral neck stress fracture, or a tibial navicular fracture.

SUMMARY

Based on experience, the authors believe that MR imaging is a useful tool in the assessment and management of stress fractures and stress phenomenum of bone. The use of standard, graded MR evaluation aides the assessment of a repetitive stress injury to bone by allowing a more accurate diagnosis of bone injury. This more accurate assessment has predictive value in estimating the duration of disability. The use of a standard, graded MR evaluation aides the management of repetitive stress

References (16)

  • J.L. Kelsay et al.

    Effects of fiber from fruits and vegetables on metabolic responses of human subjects II: Calcium, magnesium, iron and silicon balances

    Am J Clin Nutr

    (1979)
  • E.A. Arendt et al.

    Stress injuries of bone

  • Arendt EA, Griffiths HJ, Golloway HR, et al. The MR spectrum of stress injury to bone and its clinical relevance. Am J...
  • D.B. Burr et al.

    Experimental stress fractures of the tibia

    J Bone Joint Surg

    (1990)
  • R. Chisin et al.

    Clinical significance of nonfocal scintigraphic findings in suspected tibial stress fractures

    Clin Orthop

    (1987)
  • W.N. Floyd et al.

    Roentgenologic diagnosis of stress fractures and stress reactions

    South Med J

    (1987)
  • M. Fredericson et al.

    Tibial stress reaction in runners: Correlation of clinical symptoms and scintigraphy with a new magnetic resonance imaging grading system

    Am J Sports Med

    (1995)
  • H.J. Griffiths et al.

    Bone bruises: Their aetiology and importance

    Imaging

    (1995)
There are more references available in the full text version of this article.

Cited by (238)

  • Lumbosacral Spondylolysis and Spondylolisthesis

    2021, Clinics in Sports Medicine
View all citing articles on Scopus

Address reprint requests to Harry J. Griffiths, MD, University of Minnesota Hospital and Clinic, Department of Radiology, 420 Delaware Street S.E., Minneapolis, MN 55455

*

Departments of Orthopaedics and Radiology, University of Minnesota Hospital and Clinic, Minneapolis, Minnesota

View full text