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08.07.2011 Рентгенография стопы. Os peroneum

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Возможно, Os peroneum,

Возможно, Os peroneum, сверхкомплектная кубовидная кость, "может являться сесамовидной костью в сухожилии длинной малоберцовой мышцы, описаны подобные образования в качестве костных фрагментов при переломе плюсневой кости (Gnilka), как проявление обызвествленного перитендинита (Dittert)."

 
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Os peroneum An os peroneum

Os peroneum

An os peroneum is a small accessory bone located just proximal to the base of the 5th metatarsal and located within the substance of peroneus longus tendon as it arches around the cuboid. It is very common, seen in up to 26% of feet.

 

Radiography and US of Os Peroneum Fractures and Associated Peroneal Tendon Injuries: Initial Experience

  1. Monica K. Brigido, MD,
  2. David P. Fessell, MD,
  3. Jon A. Jacobson, MD,
  4. David S. Widman, MD,
  5. Joseph G. Craig, MB, ChB,
  6. David A. Jamadar, MB, BS and
  7. Marnix T. van Holsbeeck, MD

+ Author Affiliations


  1. 1From the Department of Radiology, University of Michigan Medical Center, 1500 E Medical Center Dr, TC-2808, Ann Arbor, MI 48109-0326 (M.K.B., J.A.J., D.A.J.); Department of Radiology, William Beaumont Hospital, Royal Oak, Mich (D.P.F.); and Department of Radiology, Henry Ford Hospital, Detroit, Mich (D.S.W., J.G.C., M.T.v.H.). Received June 16, 2004; revision requested August 25; revision received November 24; accepted December 24.
  1. Address correspondence to
    M.K.B. (e-mail: mbrigido@umich.edu).

Abstract

PURPOSE: To retrospectively evaluate the imaging features of os peroneum fractures and associated peroneus longus tendon injuries at radiography and ultrasonography (US) and to retrospectively compare these imaging features with those of multipartite os peroneum.

MATERIALS AND METHODS: Institutional review board approval was obtained and informed consent was waived for this HIPAA-compliant study. Retrospective review of findings in nine patients (five men, four women; age range, 35–59 years) with os peroneum fracture at radiography and lateral foot pain after injury who had undergone US of the foot was performed. Three patients underwent magnetic resonance (MR) imaging, and two underwent surgery. Os peroneum fragment separation and displacement relative to the calcaneocuboid joint were measured on radiographs. Os peroneum fracture and peroneus longus tendon injuries were characterized with US and MR imaging. Review of 43 foot radiographs obtained in 36 control subjects (eight men, 28 women; age range, 18–84 years) who were found to have an os peroneum at radiography but were asymptomatic in that area was completed to measure os peroneum distance from the calcaneocuboid joint and bipartite os peroneum fragment distraction.

RESULTS: Os peroneum fragment separation of 6 mm or more or displacement of the proximal fragment by 10 mm or more on a lateral radiograph or 20 mm or more on an oblique radiograph was associated with full-thickness peroneus longus tendon tear in seven of seven patients (100%). Os peroneum fragment separation of 2 mm or less or proximal displacement of 8 mm or less was associated with normal tendons, partial-thickness tears, or tendinosis. In the control subjects, os peroneum location ranged from 7 mm proximal to 8 mm distal to the calcaneocuboid joint on lateral radiographs and from 9 mm proximal to 8 mm distal to the joint on oblique radiographs. Bipartite os peroneum fragment separation was 2 mm or less.

CONCLUSION: Os peroneum fragment separation of 6 mm or more suggests os peroneum fracture and associated full-thickness peroneus longus tendon tear. Separation of 2 mm or less may be seen with nondisplaced os peroneum fractures and bipartite os peroneum.

© RSNA, 2005

The os peroneum is a sesamoid bone located within the peroneus longus tendon in the region of the cuboid tunnel (Fig 1) (1,2). It is present in its fully ossified form in up to 20% of adults and is bilateral in approximately 60% of cases (1,3,4). A bipartite appearance is a frequent finding, occurring in approximately 30% of adults with an os peroneum (4).

Figure 1.

Illustration of lateral foot shows os peroneum (white arrow) and peroneus longus tendon (black arrows).

A fracture of an os peroneum can occur after trauma and may be associated with a peroneus longus tendon tear (35). Recognition of an os peroneum fracture and associated peroneus longus tendon injuries is important because misdiagnosis can result in meaningful sequelae, including ankle instability and peroneal compartment syndrome (57). The initial diagnosis of os peroneum fracture can be overlooked or delayed owing to a low index of suspicion, nonspecific symptoms, or confusion with a bipartite os peroneum (5,7).

In our clinical practice, we have noted cases of displaced os peroneum fracture fragments at radiography that have simulated other types of fractures, intraarticular bodies, and other accessory ossicles. In addition, we have identified unexpected os peroneum fractures at ultrasonography (US) in patients with lateral foot pain—fractures that, to our knowledge, have not been previously described. Therefore, the purpose of our study was to retrospectively evaluate the imaging features of os peroneum fractures and associated peroneus longus tendon injuries at radiography and US and to retrospectively compare these imaging features with those of multipartite os peroneum.

MATERIALS AND METHODS

Institutional review board approval was obtained and informed consent was waived for patients and control subjects at the institutions participating in this study, which was compliant with the Health Insurance Portability and Accountability Act.

Patients and Control Subjects

Nine patients with a history of acute injury and lateral foot pain who had undergone US evaluation of the lateral foot and who had radiographic evidence of os peroneum fracture were identified between July 1998 and April 2000 through the clinical experience of one of the authors (D.P.F., who had 2 years of musculoskeletal radiology experience). The patients included five men and four women who ranged in age from 35 to 59 years (mean age, 47 years). Two of the patients had diabetes mellitus, and one patient had rheumatoid arthritis. The criterion for os peroneum fracture at radiography was cortical discontinuity with nonsclerotic margins and a “pieces of a puzzle” appearance (46,8). Lateral and oblique views were available for seven of the nine patients. Oblique views were not available for two patients. Comparison radiographs for the evaluation of the progression of diastasis were not available. Medical records were also reviewed by two of the authors (D.P.F. and M.K.B.) to determine the history of surgical or magnetic resonance (MR) imaging evaluation of the foot and ankle.

An additional group of 36 consecutive control subjects (eight men and 28 women; age range, 18–84 years; mean age, 47 years) was identified through the clinical experience of one of the authors (D.A.J., who had 6 years of musculoskeletal radiology experience) between September 1999 and April 2004. All 43 radiographs obtained in this group (seven of the subjects had undergone radiography of both feet) revealed a unipartite or bipartite os peroneum. Lateral and oblique views of the foot were available for all control subjects. The criterion for os peroneum was the presence of a bone ossicle or ossicles with smooth, rounded, and sclerotic margins at the lateral margin of the cuboid or calcaneocuboid joint. The subjects had no history of injury or pain in the lateral foot. Foot images were ordered at the discretion of referring physicians to rule out, among other conditions, osteoarthritis, erosive changes, and the presence of foreign bodies or to evaluate heel and medial foot pain. Medical records were reviewed by one of the authors (M.K.B.) to determine if any of these subjects had undergone US or MR imaging of the foot and ankle.

Imaging Technique

Radiography consisted of routine digital and film-screen examinations of the foot and ankle. US was performed with 7.5–10.0-MHz linear-array transducers (Model 5200; Acoustic Imaging Technologies, Phoenix, Ariz) or 10.5–12.5-MHz linear-array transducers (HDI 3000 or HDI 5000; Advanced Technology Laboratories, Bothell, Wash) by one of five radiologists (including D.P.F. and M.T.v.H.) who had 2–15 years of musculoskeletal US experience.

MR imaging was performed with a 1.5-T MR unit (Signa; GE Medical Systems, Milwaukee, Wis) and an extremity coil. The typical field of view was 12–14 cm, the section thickness was 3–4 mm, the intersection gap was 0.5–1.5 mm, the matrix was 256 × 192–256, and the echo train length was one or two. All patients underwent T2-weighted fast spin-echo fat saturation imaging in the transverse, sagittal, and coronal planes (repetition time msec/echo time msec, 3000–3500/80–90). An additional MR imaging protocol for one patient included the acquisition of (a) transverse, coronal, and sagittal T1-weighted spin-echo images (500–700/14–16); (b) transverse and sagittal intermediate-weighted fast spin-echo fat saturation images (3000–3500/30–40); and (c) oblique sagittal T1-weighted gradient-echo images. Additional MR imaging for the other patients included transverse, sagittal, and coronal T2-weighted fast spin-echo fat saturation imaging and coronal intermediate-weighted fast spin-echo imaging. The radiographic, US, and MR imaging examinations were ordered by the referring physicians as part of the diagnostic evaluation for ankle and foot pain.

Image Review

Radiographic and US images obtained in the nine patients were retrospectively reviewed at the same time in an unblinded fashion by three fellowship-trained musculoskeletal radiologists (M.K.B., D.P.F., and J.A.J.; range of experience, 1–6 years), and opinions were reached by consensus. Three of the nine patients had also undergone MR imaging, and these images were also reviewed in an unblinded fashion by the same authors, with opinions reached by consensus. Radiographs were reviewed for the presence of os peroneum fracture by using criteria similar to those described above. The maximum distance of fragment separation was measured to the closest millimeter by using a ruler. The maximum distance from the most posterior aspect of the proximal fragment to the calcaneocuboid joint was also measured on both lateral and oblique radiographs. Oblique radiographs were not obtained in two patients.

US images were reviewed for the presence of ossific fragments in the region of the peroneus longus tendon, as well as peroneus longus and brevis tendon abnormalities. The US findings of os peroneum were characterized with regard to location, contour, echogenicity, and shadowing. At US, a normal tendon was defined as one that had a uniform hyperechoic fibrillar appearance; tendinosis and partial-thickness tear were characterized by hypoechoic swelling and a hypoechoic or anechoic cleft, respectively; and a full-thickness tear was defined as complete tendon disruption with retraction (9).

MR images were reviewed for the presence of bone fragments in the region of the peroneus longus tendon, peroneus longus tendon abnormality, and the signal intensity of the fracture fragments. At MR imaging, a normal tendon was defined as one that had uniform thickness and low signal intensity on images obtained with all sequences, while tendinosis was defined as a situation in which the tendon was enlarged and had abnormally increased signal intensity that was similar to that of muscle on images obtained with all sequences, partial-thickness tear was characterized by an incomplete cleft that had the signal intensity of fluid on T2-weighted images, and full-thickness tear was defined as complete tendon disruption with retraction (10).

The 43 foot radiographs obtained in the control subjects were retrospectively reviewed by two of the authors (M.K.B. and D.A.J., with 3 and 11 years of experience in musculoskeletal radiology, respectively), and agreement was reached by consensus. The maximum distance from the most posterior aspect of the os peroneum to the calcaneocuboid joint was measured on both lateral and oblique views. The os peroneum was classified as either unipartite or multipartite, with the latter kind characterized by smooth, rounded, and sclerotic margins (46,8). If a multipartite os peroneum was present, the maximum distance of ossicle fragment separation was measured to the closest millimeter by using a ruler. The os peroneum was also characterized on US and MR images with regard to its location, contour, echogenicity, shadowing, and signal intensity.