DOI: 10.1148/rg.253045123
RadioGraphics 2005;25:587-602
© RSNA, 2005
Normal Variants and Diseases of the Peroneal Tendons and Superior Peroneal Retinaculum: MR Imaging Features1
Xiao-Tian Wang, MD,
Zehava Sadka Rosenberg, MD,
Michael B. Mechlin, MD and
Mark E. Schweitzer, MD
1 From the Department of Radiology, Hospital for Joint Diseases/New York University Medical Center, 301 E 17th St, New York, NY 10003. Recipient of a Certificate of Merit award for an education exhibit at the 2003 RSNA Scientific Assembly. Received June 1, 2004; revision requested July 16 and received November 15; accepted November 16. All authors have no financial relationships to disclose.
Address correspondence to X.W. (e-mail: wangx06{at}endeavor.med.nyu.edu).
 |
Abstract
|
|---|
Diseases of the peroneal tendons and superior peroneal retinaculum (SPR) are frequently underdiagnosed causes of lateral ankle pain and instability. Common diseases include tenosynovitis, rupture, and dislocation of the peroneal tendons as well as injuries to the SPR. Many anatomic variants, such as a flat or convex retromalleolar fibular groove, hypertrophy of the peroneal tubercle, an accessory peroneus quartus muscle, a low-lying peroneus brevis muscle belly, or an os peroneum, may be associated with or predispose to lateral ankle disease. Magnetic resonance (MR) imaging is excellent for detecting soft-tissue and bone variants and abnormalities related to the lateral ankle. Knowledge of the MR imaging appearances of these entities aids radiologists in making the precise diagnosis of disorders of the peroneal tendons and SPR. Pitfalls and normal variants of the peroneal tendons, including magic angle phenomenon, pseudosubluxation of the peroneus brevis tendon, a bifurcated or mildly crescentic peroneus brevis tendon, insertion of the peroneus quartus tendon into the peroneus brevis tendon, and the presence of an os peroneum are important to recognize. It is also useful to be familiar with the MR imaging appearances of SPR injuries, which can be an overlooked but treatable cause of lateral ankle pain and instability.
© RSNA, 2005
Abbreviations: SPR = superior peroneal retinaculum
|
LEARNING OBJECTIVES FOR TEST 2
|
|---|
After reading this article and taking the test, the reader will be able to:
- Discuss the anatomic variants and MR imaging pitfalls of the peroneus brevis and peroneus longus tendons.
- Describe the MR imaging features of diseases of the peroneal tendons, including tenosynovitis, rupture, and dislocation.
- Recognize the MR imaging features of the normal anatomy and injuries of the superior peroneal retinaculum.
|
Introduction
|
|---|
Disorders of the peroneal tendons such as tenosynovitis, rupture, and dislocation are increasingly being recognized as causes of lateral ankle pain and as such are gaining attention in the literature. However, patient presentation and subsequent diagnosis of peroneal tendon diseases are often delayed (1). A common complaint is lateral ankle or hindfoot pain, which usually worsens with activity. Patients may also complain of a "snapping" or "popping" sensation in the ankle. Many patients do not recall a specific episode of trauma (2). Peroneal tendon diseases can also be associated with systemic conditions such as rheumatoid arthritis (3), psoriasis, diabetes (4), hypothyroidism, and local steroid injection.
The intimate relationship of the superior peroneal retinaculum (SPR) with the peroneal tendons contributes to frequent concomitant diseases, complicating the clinical diagnosis and the treatment of lateral ankle pain. Chronic insufficiency or tear of the SPR allows the peroneal tendons to dislocate out of the fibular groove and predisposes to peroneal tendon tears. Therefore, recognition of SPR injuries is important in guiding treatment options.
In this article, we review the normal anatomy, variants, and magnetic resonance (MR) imaging pitfalls of the peroneal tendons and SPR. We also discuss the pathogenesis, MR imaging features, and treatment of diseases of the peroneal tendons such as tenosynovitis, rupture, and dislocation. In addition, we discuss and illustrate the four types of SPR injuries with emphasis on their typical MR imaging appearances.
|
Normal Anatomy
|
|---|
The peroneus brevis muscle arises from the distal two-thirds of the lateral fibula and the adjacent intermuscular septa and inserts onto the tuberosity on the lateral aspect of the proximal fifth metatarsal bone. Its primary function is plantar flexion and eversion of the foot at the ankle. The peroneus longus muscle originates from the lateral condyle of the tibia, the head and proximal two-thirds of the lateral fibula, the intermuscular septa, and adjacent fascia. Its tendon passes inferior to the cuboid bone in a bone tunnel termed the cuboid tunnel and inserts onto the plantar surface of the first cuneiform bone laterally and the proximal first metatarsal bone. The primary action of the peroneus longus muscle is to produce plantar flexion of the first ray of the foot. It also produces plantar flexion and eversion of the foot at the ankle. In addition, the peroneal tendons are important stabilizers of the ankle joint.
The peroneal tendons share a common peroneal synovial sheath posterior to the lateral malleolus and descend down the lateral leg, passing through a fibro-osseous tunnel posterior to the lateral malleolus called the retromalleolar groove (Fig 1). The peroneus brevis tendon is usually located anteromedial to the peroneus longus tendon within the groove. The peroneal tendons are stabilized by the SPR and by the calcaneofibular ligament at the level of the retromalleolar groove. More inferiorly, the peroneal tendons are held in place by the inferior peroneal retinaculum.
View larger version (80K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Drawing illustrates the lateral ankle. The peroneus brevis (PB) and peroneus longus (PL) tendons descend posterior to the lateral malleolus and are held in place by the superior peroneal retinaculum (SPR) and inferior peroneal retinaculum (IPR). F = fibula. (Courtesy of Salvador Beltran, MD, Albons, Girona, Spain.)
|
|
The SPR forms the posterolateral border of the retromalleolar groove and is composed of a fibrous band originating from the posterior ridge of the distal fibula. The SPR extends posteriorly and inferiorly to insert onto the lateral wall of the calcaneus (Fig 1). The SPR is often associated, at or close to its fibular origin, with a small triangular fibrous ridge that presumably acts to deepen the retromalleolar groove. Numerous anatomic variants of the SPR exist, including conjoined insertion onto the aponeurosis of the Achilles tendon and the lateral calcaneus and isolated attachment to the Achilles tendon.
|
MR Imaging Technique
|
|---|
At our institution, routine ankle MR imaging is performed with the foot in neutral position, which is at about 20° plantar flexion. The ankle is imaged in axial, sagittal, and coronal planes. Axial planes provide the best definition of tendon contours, synovial sheath content, and surrounding structures such as the retinacula and the retromalleolar groove. Sagittal images are useful in assessing the longitudinal extent of tendon disease. We recommend obtaining axial images with T1-weighted or proton-density–weighted sequences and fat-suppressed T2-weighted sequences. Fat-saturation techniques are frequently used with T2-weighted sequences to improve visualization of fluid and edema. The short inversion time inversion-recovery sequence is very sensitive to fluid and edema and is best used in the sagittal plane. Coronal T1-weighted or fat-suppressed T2-weighted images may occasionally help confirm peroneal tendon disease.
On axial MR images of the ankle, the peroneal tendons appear as low-signal-intensity structures posterior to the lateral malleolus, with the peroneus brevis tendon usually anteromedial to the peroneus longus tendon (Fig 2). Heterogeneity and increased signal intensity of the tendons are usually indicative of disease (5–7). The contour of the peroneus brevis tendon is flat or mildly crescentic as it conforms to the shape of the retromalleolar groove, whereas the peroneus longus tendon appears globular in configuration.
View larger version (174K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2a. Axial (a) and sagittal (b) T1-weighted MR images demonstrate normal peroneus brevis (short arrow) and peroneus longus (long arrow) tendons descending posterior to the lateral malleolus (F). The peroneus brevis tendon is mildly crescentic in configuration on the axial image.
|
|
View larger version (179K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2b. Axial (a) and sagittal (b) T1-weighted MR images demonstrate normal peroneus brevis (short arrow) and peroneus longus (long arrow) tendons descending posterior to the lateral malleolus (F). The peroneus brevis tendon is mildly crescentic in configuration on the axial image.
|
|
It is sometimes difficult to differentiate the peroneal tendons within their common tendon sheath when the foot is in dorsiflexion. A thin fat plane, best seen when the foot is imaged at about 20° plantar flexion, allows differentiation of the tendons.
|
Variants and Pitfalls
|
|---|
Magic Angle Phenomenon
The magic angle phenomenon produces increased signal intensity within normal tendons, since the fibers form an angle of about 55° with the main magnetic vector (Fig 3). This phenomenon is more prominent when a short echo time is used (eg, with T1-weighted, proton-density–weighted, and gradient-echo sequences). The peroneal tendons are susceptible to the magic angle effect as they descend down the ankle. Thus, imaging with the foot in mild plantar flexion (approximately 20°) can help decrease the magic angle effect (6).
View larger version (163K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3. Magic angle phenomenon. Axial T1-weighted MR image obtained with the patient’s ankle in dorsiflexion shows the peroneus brevis tendon with increased signal intensity (short arrow), a finding that simulates disease. On an axial image obtained with the ankle at about 20° plantar flexion (not shown), the tendon had normal low signal intensity. Long arrow indicates the peroneus longus tendon, C = calcaneus.
|
|
Morphologic Variations in the Retromalleolar Fibular Groove
A smooth and concave retromalleolar groove about 1 cm above the lateral ankle joint is seen in 82% of individuals (Fig 4). Flat or convex retromalleolar grooves are present in 11% and 7% of individuals, respectively, and can predispose to lateral dislocation and longitudinal tears of the peroneal tendons. In addition, the contour of the groove can be irregular, predisposing to peroneal tendon tears (Fig 5).
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4. Axial T1-weighted MR image depicts a normal concave retromalleolar groove (arrowheads). A fibrous ridge is noted at the origin of the SPR (arrow). pb = peroneus brevis tendon, pl = peroneus longus tendon.
|
|
Pseudosubluxation of the Peroneus Brevis Tendon
Occasionally, the peroneus brevis tendon is partially medial to the medial edge of the fibular groove on axial MR images, thereby mimicking medial subluxation of the tendon. This is a normal finding secondary to the oblique course the tendon takes as it descends down the ankle. When the peroneus brevis tendon is located medial rather than anteromedial to the peroneus longus tendon in the retromalleolar groove, pseudosubluxation is more frequently seen (Fig 6). Supination of the foot can further accentuate this finding.
View larger version (191K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6. Medial pseudosubluxation of the peroneus brevis tendon. Axial T1-weighted MR image demonstrates the peroneus brevis tendon (short arrow) medial to the tip of the fibula simulating a subluxation. Long arrow indicates the peroneus longus tendon.
|
|
Enlarged Protuberances of the Lateral Calcaneal Wall
Two protuberances may be seen along the lateral wall of the calcaneus: the peroneal tubercle and the retrotrochlear eminence (Fig 7). The peroneal tubercle is present in 40% of individuals and separates the peroneus brevis tendon from the peroneus longus tendon. Hypertrophy of the peroneal tubercle may irritate the peroneus longus tendon sheath, leading to tenosynovitis and tear (Fig 8). An adventitial bursa can also develop over the peroneal tubercle and may be symptomatic when inflamed.
View larger version (169K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7. Axial T1-weighted MR image shows a normal peroneal tubercle (large*) and retrotrochlear eminence (small *). The peroneal tubercle separates the peroneal brevis (short arrow) and peroneus longus (long arrow) tendons.
|
|
View larger version (172K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Hypertrophic peroneal tubercle. Axial (a) and coronal (b) T1-weighted MR images depict a bone protuberance (*) between the peroneus brevis (short arrow) and peroneus longus (long arrow) tendons.
|
|
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Hypertrophic peroneal tubercle. Axial (a) and coronal (b) T1-weighted MR images depict a bone protuberance (*) between the peroneus brevis (short arrow) and peroneus longus (long arrow) tendons.
|
|
The retrotrochlear eminence is seen in 98% of individuals and is located posterior to the peroneal tubercle and the peroneal tendons. Hypertrophy of the retrotrochlear eminence is often associated with an accessory peroneus quartus muscle (Fig 9) (8).
View larger version (164K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9. Axial T1-weighted MR image depicts a hypertrophic retrotrochlear eminence (*). A peroneus quartus tendon, which is commonly associated with hypertrophy of the retrotrochlear eminence, is also identified (arrow).
|
|
Peroneus Quartus Muscle
The accessory peroneal muscles are a group of muscles in the lateral aspect of the leg whose origins and insertion sites vary greatly. Many accessory peroneal muscles have been described, such as the peroneus quartus (Otto), peroneus-calcaneus externum (Hecker), peroneus accessories (White), peroneus digiti minimi, and peroneus digiti quinti (Testut). The confusing terminology has prompted some authors to view all lateral compartment muscles as peroneal variants and to define a peroneus quartus muscle as "a muscle arising from the lower leg and inserting onto the calcaneus" (9).
The peroneus quartus muscle is the most frequently reported accessory peroneal muscle (Fig 10). Its prevalence, based on the results of cadaveric dissections, varies approximately from 12% to 22% (9,10). The peroneus quartus muscle originates at the distal lateral portion of the fibula and descends medial and posterior to the peroneal tendons. Its site of insertion is variable and includes the retrotrochlear eminence of the calcaneus, the phalanx or the metatarsal bone of the fifth toe, the peroneal tendons, the lateral retinaculum of the ankle, and the cuboid bone. As stated earlier, some authors may not define all of these muscles with variable insertions as peroneus quartus muscles.
View larger version (79K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10. Drawing illustrates a peroneus quartus muscle (arrowheads) located posterior to the peroneus brevis (long straight arrow) and peroneus longus (short straight arrow) tendons. Its most common insertion site is the retrotrochlear eminence of the calcaneus (curved arrow). (Courtesy of Salvador Beltran, MD, Albons, Girona, Spain.)
|
|
The peroneus quartus muscle is usually asymptomatic. Occasionally, however, it can cause crowding in the retromalleolar groove, predisposing to peroneus brevis tendon dislocation and tear.
The peroneus quartus muscle is best demonstrated at axial MR imaging. It is located posteromedial to the peroneus brevis muscle and is isointense relative to other muscles (Figs 11, 12) (8). The peroneus quartus muscle is usually separated from the peroneus brevis muscle by a fat plane. Occasionally, close approximation (Fig 13) or incorporation of the tendinous slips of the peroneus quartus muscle into the peroneus brevis tendon may mimic a peroneus brevis tendon tear. With more distal insertions, the peroneus quartus tendon can usually be followed on sequential axial images down to its insertion onto the retrotrochlear eminence (Figs 9, 11). Less frequently, direct insertion of the muscle belly onto the calcaneus is noted (Fig 12).
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11. Sequential axial T1-weighted MR images show a peroneus quartus muscle with the muscle belly (m) tapering into a small tendon (arrow) as the muscle descends posterior to the peroneal tendons. A small retrotrochlear eminence is also noted (*).
|
|
View larger version (164K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13. Peroneus quartus tendon simulating a torn peroneus brevis tendon. Axial T1-weighted MR image demonstrates a peroneus quartus tendon (long arrow) in proximity to the peroneus brevis tendon (short arrow). This finding should not be mistaken for a peroneus brevis tendon tear.
|
|
Low-lying Peroneus Brevis Muscle Belly
A low-lying peroneus brevis muscle belly is defined as extension of the muscle tissue distal to the fibular groove. Its presence may cause crowding in the retromalleolar groove and predisposes to peroneal tendon diseases and SPR injuries.
One should keep in mind, however, that the distal extension of the peroneus brevis muscle belly changes with foot position. In a group of asymptomatic volunteers, extension of the muscle belly into the retromalleolar groove or beyond was seen with the foot in dorsiflexion (Fig 14) and, less frequently, with the foot in plantar flexion (11). Therefore, care should be taken before incriminating a low-lying peroneus brevis muscle belly as the cause of a peroneal tendon disorder.
View larger version (154K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14. Low position of the peroneus brevis muscle in a foot in dorsiflexion. Axial T1-weighted MR image shows a peroneus brevis muscle belly (arrow) at the level of the ankle joint.
|
|
Os Peroneum
The os peroneum is a sesamoid bone within the peroneus longus tendon that is found in the region of the cuboid bone. The prevalence of the os peroneum is unknown. When ossified, it is visible on 20% of foot radiographs (5,6). At MR imaging, it appears as a discrete area of bone marrow signal intensity or cartilage signal intensity with all pulse sequences and should not be confused with an intrasubstance tear of the peroneus longus tendon (Fig 15). Patients may present with a painful os peroneum syndrome relating to os peroneum fracture, diastasis of a multipartite os peroneum, or various peroneus longus tendon diseases ranging from tenosynovitis to tendon rupture (12). Proximal migration of the os peroneum indicates a tear of the peroneus longus tendon.
View larger version (177K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15. Oblique coronal T2-weighted MR image shows the os peroneum (straight arrow), which should not be mistaken for a peroneus longus tendon tear. The peroneus longus tendon (curved arrow) is normal. Cu = cuboid bone.
|
|
|
Diseases of the Peroneal Tendons
|
|---|
Peroneal Tenosynovitis
The pathogenesis of peroneal tenosynovitis is thought to be secondary to increased stress around fixed pulleys such as the retromalleolar groove, peroneal tubercle, or undersurface of the cuboid bone. Other causes include ankle inversion injuries and lateral malleolar and calcaneal fractures (13). Acute peroneal tenosynovitis is typically seen in athletes who resume activity after a layoff. It is also common in ballet dancers who spend long periods of time standing in half-pointe. Patients present with swelling and tenderness along the tendon sheath.
A sliver of fluid noted within the common peroneal tendon sheath at MR imaging is considered to be physiologic (ie, normal), whereas a large amount of fluid is usually diagnostic for chronic tenosynovitis (Fig 16). However, fluid accumulation in the common peroneal tendon sheath may also be caused by a calcaneofibular ligamentous tear, owing to the intimate relationship between the calcaneofibular ligament and the common peroneal tendon sheath (Fig 17). Thus, examination of the lateral collateral ligaments is recommended before attributing the presence of fluid in the common peroneal tendon sheath to tenosynovitis.
View larger version (140K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17. Axial T1-weighted MR image demonstrates the calcaneofibular ligament (arrowheads) in proximity to the peroneal tendons (arrow). Tear of the calcaneofibular ligament can cause fluid accumulation in the peroneal tendon sheath and simulate tenosynovitis.
|
|
Stenosing tenosynovitis occurs when synovial proliferation and fibrosis surround the tendons, preventing their free excursion. At MR imaging, stenosing tenosynovitis is depicted as thickened synovium with linear areas of intermediate or low signal intensity within the synovial fluid with all pulse sequences (Fig 18). Gadolinium enhancement and complete obliteration of the fluid may also be seen.
View larger version (120K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18. Stenosing tenosynovitis following ankle ligamentous repair. Axial T1-weighted MR image demonstrates abundant low-signal-intensity scar tissue lateral to the calcaneus (arrows). The tendons cannot be distinguished from the scar tissue.
|
|
Bone marrow edema along the lateral wall of the calcaneus or within bone protuberances such as the peroneal tubercle is uncommonly associated with tenosynovitis or rupture of the peroneal tendons.
Initial treatment of peroneal tenosynovitis includes rest, immobilization, anti-inflammatory medication, and protected (crutch) ambulation. The use of local anesthetic injection or peritendinous steroid injection has not shown long-term benefits. Surgical decompression is offered to patients with chronic symptoms (13).
Peroneus Brevis Tendon Rupture
Longitudinal tears or splits of the peroneus brevis tendon, also referred to as peroneal split syndrome, are encountered in young athletes as well as in the elderly. The clinical symptoms of pain and swelling tend to be more prominent in younger patients, whereas elderly individuals may be completely asymptomatic (14).
As mentioned earlier, several normal variants and pathologic conditions are associated with or predispose to peroneus brevis tendon tear. These entities include insufficiency of the SPR, thickening of the calcaneofibular ligament, crowding of the retromalleolar groove due to the presence of a low-lying peroneus brevis muscle belly or of a peroneus quartus muscle, retromalleolar groove irregularity, and peroneal tendon dislocations.
The peroneus brevis tendon is susceptible to degenerative tears due to its vulnerable position in between the bony retromalleolar groove and the peroneus longus tendon. As the foot undergoes dorsiflexion, the peroneus brevis tendon is repeatedly compressed between the peroneus longus tendon and the lateral malleolus, predisposing to a tear (Fig 19). Once a tear is initiated, the peroneus longus tendon migrates forward into the peroneus brevis tendon tear, thereby preventing healing.
View larger version (101K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19. Drawing illustrates a torn peroneus brevis tendon (PB) between the fibula (F) and the peroneus longus tendon (PL). (Courtesy of Salvador Beltran, MD, Albons, Girona, Spain.)
|
|
With SPR insufficiency or tear, the peroneus brevis tendon undergoes increased friction against the sharp lateral ridge of the fibula as it subluxates in and out of the retromalleolar groove. This increased friction also predisposes to tendon tear.
On axial MR images, the torn peroneus brevis tendon has a characteristic C-shaped configuration, with formation of medial and lateral "limbs" that partially envelop the peroneus longus tendon (Fig 20 ) (15,16). The central portion of the peroneus brevis tendon anterior to the peroneus longus tendon becomes markedly thinned and is often not well visualized. Clefts, fragmentation, irregularity of tendon contour, and increased signal intensity on T1- and T2-weighted images are other common secondary findings in peroneus brevis tendon tear. The peroneus longus tendon migrates anteriorly and may abut the fibular groove; consequently, concomitant peroneus longus tendon tear is seen in up to one-third of peroneus brevis tendon tears (Fig 21).
View larger version (172K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20a. Longitudinal tears of the peroneus brevis tendon. (a) Axial T1-weighted MR image depicts a fragmented peroneus brevis tendon (short straight arrows) with an advanced tear and a markedly thinned central portion (curved arrow). Long straight arrow indicates the peroneus longus tendon. (b) Axial T1-weighted MR image obtained in a different patient shows a split of the peroneus brevis tendon (short arrows) and anterior migration of the peroneus longus tendon (long arrow).
|
|
View larger version (173K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20b. Longitudinal tears of the peroneus brevis tendon. (a) Axial T1-weighted MR image depicts a fragmented peroneus brevis tendon (short straight arrows) with an advanced tear and a markedly thinned central portion (curved arrow). Long straight arrow indicates the peroneus longus tendon. (b) Axial T1-weighted MR image obtained in a different patient shows a split of the peroneus brevis tendon (short arrows) and anterior migration of the peroneus longus tendon (long arrow).
|
|
View larger version (136K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 21. Concomitant peroneus brevis and peroneus longus tendon tears. Axial T1-weighted MR image depicts increased intrasubstance signal intensity in both the peroneus brevis (short arrow) and peroneus longus (long arrow) tendons.
|
|
Two normal variants should be considered before the diagnosis of peroneus brevis tendon tear is entertained. As stated earlier, insertion of the peroneus quartus tendon onto the peroneus brevis tendon can simulate a tear (Fig 13). In addition, a normal bifurcated peroneus brevis tendon can be mistaken for a tear. The latter misinterpretation can be avoided by examining the muscle-tendon unit proximal to the ankle. The presence of muscle fibers around each of the bifurcated tendon slips excludes a tear. Lastly, as stated earlier, a mildly crescentic peroneus brevis tendon at the retromalleolar groove is a normal finding (Fig 2a) and should not be mistaken for a tear.
Sobel et al (17) proposed a classification system for tears of the peroneus brevis tendon. According to this system, grade 1 tear is a splayed tendon without a discrete tear, grade 2 tear is a partial-thickness split of less than 1 cm, grade 3 tear is a full-thickness split of less than 2 cm, and grade 4 tear is a full-thickness split of more than 2 cm. However, this grading system does not correlate with clinical management, and we do not routinely grade peroneal tendon tears in our reports.
Treatment of peroneus brevis tendon tears is initially conservative and includes anti-inflammatory medication, rest, orthotic treatment, and cast placement. In refractory cases and in patients with associated chronic ankle instability, surgical intervention such as debridement, resuturing, and attachment to the peroneus longus tendon (tenodesis) may be performed (Fig 22). Associated conditions such as SPR incompetence, retromalleolar groove irregularity, and crowding by accessory muscles can also be corrected surgically (18).
View larger version (115K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 22. Peroneus brevis tendon tear. Intraoperative photograph shows tearing in the central portion of the peroneus brevis tendon (arrows). This tearing was treated with suturing. (Courtesy of Kenneth J. Mroczek, MD, Hospital for Joint Diseases, New York, NY.)
|
|
Peroneus Longus Tendon Rupture
Tear of the peroneus longus tendon at the level of the retromalleolar groove is often associated with peroneus brevis tendon tear (Fig 23) (15). Isolated tear of the peroneus longus tendon occurs more frequently at the midfoot. Such a tear may be a sports-related injury or may be associated with trauma, such as a calcaneal fracture or a direct crushing injury to the calcaneocuboid joint (19). Increased friction of the peroneus longus tendon against either a hypertrophic peroneal tubercle or the cuboid bone as the tendon curves underneath it may also contribute to degenerative chronic tears.
View larger version (166K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 23a. (a) Complete peroneus longus tendon tear. Oblique coronal T2-weighted MR image shows absence of the peroneus longus tendon (arrows) underneath the cuboid bone (*). (b) Oblique coronal T2-weighted MR image obtained in a different patient shows a normal peroneus longus tendon (arrow). * = cuboid bone.
|
|
View larger version (163K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 23b. (a) Complete peroneus longus tendon tear. Oblique coronal T2-weighted MR image shows absence of the peroneus longus tendon (arrows) underneath the cuboid bone (*). (b) Oblique coronal T2-weighted MR image obtained in a different patient shows a normal peroneus longus tendon (arrow). * = cuboid bone.
|
|
The clinical diagnosis of peroneus longus tendon tear is often challenging. MR imaging should be performed in patients with persistent lateral ankle and plantar foot pain. In addition to axial and sagittal images, oblique coronal images (obtained perpendicular to the long axis of the metatarsal bones) must be obtained if a midfoot peroneus longus tendon tear is suspected (Fig 24). MR imaging findings in peroneus longus tendon tears are signal-intensity and morphologic abnormalities within the tendon, including longitudinal splits or disruptions (15). Secondary findings such as a hypertrophic peroneal tubercle (Fig 25) and bone marrow edema of the tubercle, lateral calcaneal wall, or cuboid bone can sometimes be seen (Fig 24).
View larger version (161K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 24a. (a, b) Complete peroneus longus tendon tear associated with cuboid bone marrow edema. (a) Sagittal fat-suppressed T2-weighted MR image demonstrates a thickened and retracted peroneus longus tendon (arrows). F = fibula. (b) Adjacent section from the same MR imaging study depicts high-signal-intensity bone marrow edema in the cuboid bone (white arrows). The peroneus longus tendon (black arrow) is not visualized in the cuboid tunnel. (c) Sagittal MR image obtained in a different patient shows a normal peroneus longus tendon (arrow) underneath the cuboid bone (*).
|
|
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 24b. (a, b) Complete peroneus longus tendon tear associated with cuboid bone marrow edema. (a) Sagittal fat-suppressed T2-weighted MR image demonstrates a thickened and retracted peroneus longus tendon (arrows). F = fibula. (b) Adjacent section from the same MR imaging study depicts high-signal-intensity bone marrow edema in the cuboid bone (white arrows). The peroneus longus tendon (black arrow) is not visualized in the cuboid tunnel. (c) Sagittal MR image obtained in a different patient shows a normal peroneus longus tendon (arrow) underneath the cuboid bone (*).
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 24c. (a, b) Complete peroneus longus tendon tear associated with cuboid bone marrow edema. (a) Sagittal fat-suppressed T2-weighted MR image demonstrates a thickened and retracted peroneus longus tendon (arrows). F = fibula. (b) Adjacent section from the same MR imaging study depicts high-signal-intensity bone marrow edema in the cuboid bone (white arrows). The peroneus longus tendon (black arrow) is not visualized in the cuboid tunnel. (c) Sagittal MR image obtained in a different patient shows a normal peroneus longus tendon (arrow) underneath the cuboid bone (*).
|
|
View larger version (168K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 25. Axial T1-weighted MR image demonstrates a partial tear of the peroneus longus tendon (arrow) associated with a hypertrophic peroneal tubercle (T). The tendon has heterogeneous signal intensity and an irregular contour.
|
|
Avulsion fracture of the os peroneum can be associated with acute peroneus longus tendon tear. Diastasis and retraction of a sesamoid bone fragment attached to the proximal tendon stump is a clue to the tear. Whether the presence of an os peroneum predisposes to peroneus longus tendon tear is controversial.
Conservative treatment of peroneus longus tendon tear includes anti-inflammatory medication and immobilization, followed by rehabilitation. Stabilization with cast placement, lateral ankle braces, and orthotic treatment can also be beneficial. Surgical treatment with debridement, repair of the tear, and tenosynovectomy is reserved for severe cases (Fig 26). Removal of the os peroneum or resection of a hypertrophic peroneal tubercle can also be helpful. Surgical treatment has shown good results in preserving function and mobility (14,20).
View larger version (121K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 26. Intraoperative photograph shows surgical treatment of a peroneus longus tendon tear. Tenodesis is performed by suturing the peroneal tendons together. (Courtesy of Kenneth J. Mroczek, MD, Hospital for Joint Diseases, New York, NY.)
|
|
SPR Injuries and Peroneal Tendon Dislocation
The mechanism of injury to the SPR includes sudden dorsiflexion of the foot with concomitant violent contraction of the peroneal muscles, which can cause stripping of the SPR from its distal fibular attachment and secondary lateral dislocation of the peroneal tendons out of the retromalleolar groove. Other causes of SPR injury are congenital foot deformities, crowding of the retromalleolar groove by the peroneus quartus muscle or a low-lying peroneus brevis muscle belly, and fractures of the distal tibia and calcaneus.
Acute SPR injury manifests with ecchymosis, swelling, and pain along the lateral malleolus and may be mistaken for an ankle sprain at clinical examination, thus delaying diagnosis. A recurrent snapping or popping sensation around the ankle and positive provocative tests are indicative of chronic peroneal tendon dislocation, which is more evident clinically but can also be mistaken for chronic lateral ankle instability.
SPR injuries are graded with Oden’s classification system (Fig 27) (22). In type I injuries, the SPR and its periosteal attachment are elevated or stripped off at the level of the fibular groove, thereby forming a pouch into which the peroneal tendons can dislocate. In type II injuries, there is a tear of the SPR at its attachment to the distal fibula. Type III injuries consist of an avulsion fracture of the SPR at its attachment to the distal fibula. Type IV injuries involve a tear of the SPR at its posterior attachment. Type I SPR injury is the most common, followed by type III injury. Type II and type IV injuries are quite uncommon.
View larger version (67K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 27. Drawings illustrate Oden’s surgical classification system for SPR injuries. A normal SPR originates from the distal fibula (A). A small fibrous ridge may be found at the attachment site. In type I injury (B), the SPR is stripped off the distal fibula, forming a pouch into which the peroneal tendons can dislocate. Type II injury (C) is a tear of the SPR at its attachment to the distal fibula. Type III injury (D) is an avulsion fracture of the SPR at its attachment to the distal fibula. Type IV injury (E) is a tear of the SPR at its posterior attachment. PB = peroneus brevis tendon, PL = peroneus longus tendon. (Reprinted, with permission, from reference 21.)
|
|
At MR imaging, the SPR is best assessed in the axial plane. It normally appears as a low-signal-intensity band originating from the distal fibula at the level of the fibular groove (Fig 28) (21). A small fibrous ridge, which appears as a triangular low-signal-intensity meniscus-like structure, can occasionally be present at or close to the origin of the SPR (Figs 4, 28).
View larger version (180K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 28. Axial T1-weighted MR image shows a normal low-signal-intensity SPR (thick straight arrows) holding the peroneal tendons (curved arrow) within the retromalleolar groove. Thin straight arrow indicates the fibrous ridge at the fibular attachment site of the SPR. (Reprinted, with permission, from reference 21.)
|
|
Type I SPR injury is depicted on axial MR images as a pouch formed by a low-signal-intensity stripped-off SPR and periosteum. The peroneal tendons are often dislocated or subluxated into the pouch (Fig 29). Occasionally, the pouch may collapse against the bone (Fig 30). Careful examination of the soft tissues lateral to the distal fibula can demonstrate a linear low-signal-intensity area consistent with periosteal stripping and the pouch. Type II SPR injury will manifest as a tear of the SPR at or close to its attachment to the fibula (Fig 31). The diagnosis of type II SPR injury can sometimes be difficult, since the SPR is frequently thickened and poorly differentiated from the surrounding soft tissue in asymptomatic individuals (Fig 32). This finding should not be mistaken for a tear. Type III SPR injury may also be difficult to diagnose because the avulsed bone fragment may not always be visualized on MR images (Fig 33). However, secondary findings of lateral fibular bone defect and bone marrow edema at the level of the retromalleolar groove are suggestive of the diagnosis.
View larger version (169K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 29. Type I SPR injury. Axial spin-echo proton-density–weighted MR image demonstrates dislocation of the peroneal tendons (thick white arrow) into the pouch formed by a stripped-off SPR and periosteum (thin white arrows). The fibular groove (black arrow) is slightly convex. Degenerative changes at the posterior subtalar joint are incidentally noted. (Reprinted, with permission, from reference 21.)
|
|
View larger version (173K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 30. Type I SPR injury with a collapsed pouch in a patient with clinical recurrent peroneal tendon dislocation. Axial T1-weighted MR image shows a linear area of low signal intensity (short arrows) lateral to the distal fibula (F), a finding that is consistent with a collapsed pouch. The peroneal tendons (long arrow) are in their normal position. (Reprinted, with permission, from reference 21.)
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 31. Type II SPR injury. Axial T1-weighted MR image depicts a tear close to the fibular attachment of the SPR (black arrow). The peroneal tendons (white arrow) are dislocated laterally. The fibular groove (arrowhead) is flat.
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 32. Thickening of the SPR mimicking a type II SPR injury. On an axial T1-weighted MR image, the SPR is thickened and indistinct at its fibular attachment (arrow). The SPR was edematous but intact at surgery. (Reprinted, with permission, from reference 21.)
|
|
View larger version (165K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 33. Type III SPR injury. Axial fast spin-echo T2-weighted MR image depicts a torn and slightly retracted SPR (arrowheads). A cortical defect (straight arrow) and bone marrow edema (white *) are noted at the distal fibula. The peroneal tendons (curved arrow) are in their normal position within a convex fibular groove, but thinning and irregularity of the peroneal brevis tendon suggest impending longitudinal splits. Fluid is seen in the common peroneal tendon sheath (black *). (Reprinted, with permission, from reference 21.)
|
|
Aside from identifying and classifying SPR injuries, MR imaging (especially in the axial plane) is also helpful in identifying concomitant lateral collateral ligament tears, peroneal tendon abnormalities (Fig 34), and secondary pseudogroove of the lateral fibular cortex. MR imaging can also demonstrate predisposing factors for SPR injuries and for peroneal tendon dislocations and tears such as irregular, flat, or convex fibular grooves (Figs 31, 33, 34). Dynamic MR imaging may be useful for the detection of dislocatable peroneal tendons.
View larger version (188K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 34. Type I SPR injury with a peroneus brevis tendon tear. Axial T1-weighted MR image depicts dislocation of the peroneus brevis tendon (white arrow) into the pouch formed by the elevated periosteum and SPR (small black arrows). A small fragment of the peroneus brevis tendon (large black arrow) remains in an irregular fibular groove (arrowheads). (Reprinted, with permission, from reference 21.)
|
|
Asymptomatic and static dislocation of the peroneal tendons may not require treatment. In contrast, chronic motion of the tendons in and out of the retromalleolar groove can be painful and carries the risk of progressing to a tendon tear. Plaster cast immobilization is advocated in acute SPR tears, although the results are inconsistent. Surgical treatment is indicated in athletes and in patients with chronic pain. Groove deepening and soft-tissue reconstruction of the SPR are usually performed (23).
|
Conclusions
|
|---|
MR imaging is a valuable imaging modality for assessing disorders of the peroneal tendons and SPR. It is also useful for detecting many soft-tissue and bone variants and abnormalities that are associated with or predispose to diseases of these anatomic structures.
|
References
|
|---|
- Sammarco GJ. Peroneus longus tendon tears: acute and chronic. Foot Ankle Int
1995; 16:245–253.[Medline]
- Brandes CB, Smith RW. Characterization of patients with primary peroneus longus tendinopathy: a review of twenty-two cases. Foot Ankle Int
2000; 21:462–468.[Medline]
- Vainio K. The rheumatoid foot: a clinical study with pathological and roentgenological comments. Ann Chir Gynaecol Fenn
1956; 45(suppl 1):1–107.
- Truong DT, Dussault RG, Kaplan PA. Fracture of the os peroneum and rupture of the peroneus longus tendon as a complication of diabetic neuropathy. Skeletal Radiol
1995; 24:626–628.[Medline]
- Bencardino JT, Rosenberg ZS, Serrano LF. MR imaging features of diseases of the peroneal tendons. Magn Reson Imaging Clin N Am
2001; 9:493–505.[Medline]
- Bencardino JT, Rosenberg ZS. Normal variants and pitfalls in MR imaging of the ankle and foot. Magn Reson Imaging Clin N Am
2001; 9:447–463.[Medline]
- Mota J, Rosenberg ZS. Magnetic resonance imaging of the peroneal tendons. Top Magn Reson Imaging
1998; 9:273–285.[Medline]
- Cheung YY, Rosenberg ZS, Ramsinghani R, Beltran J, Jahss MH. Peroneus quartus muscle: MR imaging features. Radiology
1997; 202:745–750.[Abstract/Free Full Text]
- Cheung Y, Rosenberg ZS. MR imaging of the accessory muscles around the ankle. Magn Reson Imaging Clin N Am
2001; 9:465–473.[Medline]
- Sobel M, Levy ME, Bohne WH. Congenital variations of the peroneus quartus muscle: an anatomic study. Foot Ankle
1990; 11:81–89.[Medline]
- Rademaker J, Rosenberg ZS, Beltran J, Colon E. Alterations in the distal extension of the musculus peroneus brevis with foot movement. AJR Am J Roentgenol
1997; 168:787–789.[Abstract/Free Full Text]
- Sobel M, Pavlov H, Geppert MJ, et al. Painful os peroneum syndrome: a spectrum of conditions responsible for plantar lateral foot pain. Foot Ankle Int
1994; 15:112–124.[Medline]
- Gray JM, Alpar EK. Peroneal tenosynovitis following ankle sprains. Injury
2001; 32:487–489.[CrossRef][Medline]
- Saxena A, Cassidy A. Peroneal tendon injuries: an evaluation of 49 tears in 41 patients. J Foot Ankle Surg
2003; 42:215–220.[CrossRef][Medline]
- Rosenberg ZS, Beltran J, Cheung YY, Colon E, Herraiz F. MR features of longitudinal tears of the peroneus brevis tendon. AJR Am J Roentgenol
1997; 168: 141–147.[Abstract/Free Full Text]
- Schweitzer ME, Eid ME, Deely D, Wapner K, Hecht P. Using MR imaging to differentiate peroneal splits from other peroneal disorders. AJR Am J Roentgenol
1997; 168:129–133.[Abstract/Free Full Text]
- Sobel M, Geppert MJ, Olson EJ, Bohne WH, Arnoczky SP. The dynamics of peroneus brevis tendon splits: a proposed mechanism, technique of diagnosis, and classification of injury. Foot Ankle
1992; 13:413–422.[Medline]
- Karlsson J, Wiger P. Longitudinal split of the peroneus brevis tendon and lateral ankle instability: treatment of concomitant lesions. J Athl Train
2002; 37: 463–466.[Medline]
- Goodwin MI, O’Brien PJ, Connell DG. Intra-articular fracture of the calcaneus associated with rupture of the peroneus longus tendon. Injury
1993; 24:269–271.[CrossRef][Medline]
- Saxena A, Wolf SK. Peroneal tendon abnormalities: a review of 40 surgical cases. J Am Podiatr Med Assoc
2003; 93:272–282.[Abstract/Free Full Text]
- Rosenberg ZS, Bencardino J, Astion D, Schweitzer ME, Rokito A, Sheskier S. MRI features of chronic injuries of the superior peroneal retinaculum. AJR Am J Roentgenol
2003; 181:1551–1557.[Abstract/Free Full Text]
- Oden RR. Tendon injuries about the ankle resulting from skiing. Clin Orthop
1987; 216:63–69.
- Tan V, Lin SS, Okereke E. Superior peroneal retinaculoplasty: a surgical technique for peroneal subluxation. Clin Orthop
2003; 410:320–325.
This article has been cited by other articles:
|
|
|
|
 
T. M. Philbin, G. S. Landis, and B. Smith
Peroneal Tendon Injuries
J. Am. Acad. Ortho. Surg.,
May 1, 2009;
17(5):
306 - 317.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. A. Sookur, A. M. Naraghi, R. R. Bleakney, R. Jalan, O. Chan, and L. M. White
Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation
RadioGraphics,
March 1, 2008;
28(2):
481 - 499.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
D. S. Heckman, S. Reddy, D. Pedowitz, K. L. Wapner, and S. G. Parekh
Operative Treatment for Peroneal Tendon Disorders
J. Bone Joint Surg. Am.,
February 1, 2008;
90(2):
404 - 418.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
N. Saupe, B. Mengiardi, C. W. A. Pfirrmann, P. Vienne, B. Seifert, and M. Zanetti
Anatomic Variants Associated with Peroneal Tendon Disorders: MR Imaging Findings in Volunteers with Asymptomatic Ankles
Radiology,
February 1, 2007;
242(2):
509 - 517.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
LEARNING OBJECTIVES FOR TEST...
