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Radiological case of the month: Robert T. Sullivan, MD; Robert Hartman, MD; Scot E. Campbell, MD; Justin Q. Ly, MD; Douglas P. Beall, MD.

CASE SUMMARY

A 23-year-old female long-distance runner in training for an upcoming marathon presented to the clinic complaining of pain in her right lateral knee and thigh. She had recently increased her level of training to runs of 5 to 8 miles approximately 5 times a week. The patient first noted her pain upon completion of a vigorous 8-mile run. Physical examination was significant only for right lateral knee pain throughout range-of-motion testing and exacerbation of this pain with direct pressure on the lateral femoral epicondyle region.

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DIAGNOSIS

Iliotibial band syndrome

IMAGING FINDINGS

Magnetic resonance imaging (MRI) of the right knee revealed localized edema in the subcutaneous tissues around the lateral aspect of the right knee immediately superficial to a thickened iliotibial band. A small fluid collection was also noted deep to the iliotibial band adjacent to the lateral femoral condyle (Figures 1 through 4). These findings are consistent with iliotibial band syndrome.

DISCUSSION

The iliotibial band (ITB) is a thickened band of fascia that originates, in part, from the tensor fascia lata muscle and gluteus maximus muscle. The band extends inferiorly along the lateral aspect of the thigh. Proximal to the knee, the ITB is attached to the supracondylar tubercle of the lateral femoral condyle and the intermuscular septum. It inserts below the knee on Gerdy's tubercle on the anterolateral aspect of the tibia. (1)

Iliotibial band syndrome is an overuse injury that is predominantly seen in long-distance runners. (1-6) The posterior fibers of the ITB lie anterior to the lateral femoral epicondyle while the leg is in extension. At approximately 30[degrees] of flexion, the fibers of the ITB come in contact with the lateral femoral epicondyle and the proximal fibers of the lateral collateral ligament (LCL). With further flexion, the ITB, LCL, and the popliteus tendon cross one another at a single point. The mechanism of injury is friction of the ITB as it traverses over the lateral femoral epicondyle and the LCL. (1,2,4,5) As the individual runs, the leg is repeatedly ranged through 30[degrees] of flexion and the repetitive rubbing of the ITB results in focal inflammation. (3,5)

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Patients usually present to a physician complaining of nonspecific pain over the thigh and lateral aspect of the knee. Physical examination reveals pain with all flexion-extension movements of the knee, often with focal tenderness over the lateral epicondyle. The patients are usually long-distance runners, although cases occurring in cyclists have been reported. Individuals often report a recent change in their training program (increased distances, hill training, etc.). (1,3) The physical findings, however, are not specific for ITB syndrome, and the differential diagnosis includes a wide variety of disorders ranging from arthritic changes to the lateral compartment of the knee, LCL injury, popliteus or hamstring tendon strain, and/or meniscal injuries, as well as patellar subluxation/dislocation. (1,4) For this reason, some patients will have an MRI performed to assist in the evaluation.

Multiple studies have presented MRI findings in patients with ITB syndrome, including abnormal signal deep to the ITB and adjacent to the lateral femoral condyle (decreased signal on T1 and increased signal on T2). (1-4) These findings are consistent with local edema/soft-tissue inflammation. In fewer cases, signal abnormality has also been identified in the soft tissues superficial to the ITB. (3,4) In some cases, actual pockets of fluid have been identified in a compartment-like space confined laterally by the ITB and medially by the meniscocapsular junction, the lateral collateral ligament, and the lateral femoral epicondyle. (2-4) In the past, these fluid collections were believed to be within a bursa2; however, more recent cadaveric studies have shown that a true bursa is not present at this location. It is now believed that this represents secondary, or adventitious, bursa formation. (3,5)

There is disagreement regarding the significance of the ITB thickness. Original studies found the ITB to be significantly thicker in patients with ITB syndrome when compared with controls. (2) However, more recent studies have been unable to show any significant difference in ITB thickness. (1,3,4) Cadaveric studies have, in fact, shown a wide variation in the length, width, and thickness of the ITB in normal subjects. (3)

Both patient presentation and MRI findings in this case demonstrate the classic findings of ITB syndrome. MRI reveals abnormal signal in the soft tissues deep to the ITB, with some changes superficial to the ITB as well. A small amount of fluid is identified adjacent to the lateral femoral epicondyle. In this case, there is some focal thickening of the ITB, but no signal abnormality within the ITB itself.

Treatment for an individual with ITB syndrome consists primarily of ice massage, local physiotherapy, modified activity, rest, and anti-inflammatory medicines. Some have suggested the usefulness of steroid injections; however, this is not considered a primary treatment. In most cases, conservative treatment regimens will result in complete resolution of symptoms with patients returning to their previous level of activity. Surgery, required in only a small minority of patients who fail conservative measures, typically yields good results and minimal morbidity. (7) This consists of an incision across the posterior ITB perpendicular to the line of the fibers at the level of the lateral femoral condyle. In most cases, once the inflammation is initially controlled, it seldom recurs.

CONCLUSION

MR imaging is very useful in the diagnosis of ITB syndrome; the typical MR imaging findings include thickening and/or signal abnormality of the ITB with adjacent soft-tissue edema or small fluid.

REFERENCES

(1.) Nishimura G, Yamato M, Tamai K, et al. MR findings in iliotibial band syndrome. Skeletal Radiol. 1997;26:533-537.

(2.) Ekman EF, Pope T, Martin DF, et al. Magnetic resonance imaging of iliotibial band syndrome. Am J Sports Med. 1994;22:851-854.

(3.) Muhle C, Ahn JM, Yeh L, et al. Iliotibial band friction syndrome: MR imaging findings in 16 patients and MR arthrographic study of six cadaveric knees. Radiology. 1999;212:103-110.

(4.) Murphy BJ, Hechtman KS, Uribe JW, et al. Iliotibial band friction syndrome: MR imaging findings. Radiology. 1992;185:569-571.

(5.) Orchard JW, Fricker PA, Abud AT, et al. Biomechanics of iliotibial band friction syndrome in runners. Am J Sports Med. 1996;24:375-379.

(6.) Renne JW. The iliotibial band friction syndrome. J Bone Joint Surg Am. 1975;57:1110-1111.

(7.) Martens M, Libbrecht P, Burssens A surgical treatment of iliotibial band friction syndrome. Am J Sports Med. 1989;17:651-654.

Prepared by Robert T. Sullivan, MD, Department of Orthopedic Surgery, Scot E. Campbell, MD, Justin Q. Ly, MD, and Douglas P. Beall, MD, Department of Radiology and Nuclear Medicine, Wilford Hall Medical Center, San Antonio, TX; and Robert Hartman, MD, Department of Radiology, The Mayo Clinic, Rochester, MN.
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Article Details
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Author:Sullivan, Robert T.; Hartman, Robert; Campbell, Scot E.; Ly, Justin Q.; Beall, Douglas P.
Publication:Applied Radiology
Article Type:Case study
Geographic Code:1USA
Date:Jun 1, 2005
Words:1135
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