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AJR 2004; 183:985-988
© American Roentgen Ray Society

Musculoskeletal Imaging

Dynamic Sonographic Evaluation of Peroneal Tendon Subluxation

Jason Neustadter1, Steven M. Raikin2 and Levon N. Nazarian1

1 Division of Ultrasound, Thomas Jefferson University Hospital, 132 S 10th St., 7 Main, Philadelphia, PA 19107-5244.
2 Department of Orthopaedic Surgery, Thomas Jefferson University Hospital, Philadelphia, PA 19107–5244.

Received December 15, 2003; accepted after revision March 8, 2004.

 
Address correspondence to L. N. Nazarian (levon.nazarian{at}jefferson.edu).


Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
OBJECTIVE. Peroneal tendon subluxation is a major cause of posttraumatic lateral ankle pain. Because peroneal subluxation often occurs only when the foot is dorsiflexed and everted, findings on static imaging studies may appear to be normal. We therefore evaluated the effectiveness of sonography in revealing peroneal tendon subluxation in patients performing stress maneuvers.

MATERIALS AND METHODS. From June 2001 to June 2003, 13 consecutive patients (10 females and three males; mean age, 30.4 years; age range, 16–66 years) in whom peroneal tendon subluxation was clinically suspected were scanned with a high-frequency linear array transducer by an experienced sonologist. The ankles in 10 asymptomatic volunteers were also scanned. Sequential axial and longitudinal sonograms of the peroneus longus and peroneus brevis tendons at rest were obtained and evaluated for tendinitis and tendon tears. Real-time axial sonograms were then obtained while the foot was dorsiflexed and everted. Of the 13 patients, 12 had sonographic findings of peroneal tendon subluxation and underwent surgical exploration. The sonographic and surgical reports of these 12 patients were compared.

RESULTS. All 12 patients with sonographic findings of peroneal tendon subluxation were subsequently found to have subluxation at surgery. The positive predictive value of dynamic sonography for peroneal tendon subluxation was therefore 100%. Sonography revealed peroneus brevis tendon tears in five patients and a peroneus longus tear in one; all findings were confirmed at surgery, with no false-positive sonograms. Only four of the 20 asymptomatic ankles showed subluxation, and none had any other tendon abnormalities.

CONCLUSION. Sonography is an effective technique for diagnosing peroneal tendon subluxation, as well as associated tears of the peroneal tendons.


Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Peroneal tendon subluxation is an uncommon but not rare disorder that is estimated to occur in 0.3–0.5% of traumatic events to the ankle [1, 2]. Accurate diagnosis of peroneal tendon subluxation, both acute and chronic, is imperative. Surgical treatment is almost always indicated because nonsurgical treatment is seldom of benefit [3, 4]. Although clinical findings can suggest that this condition is present, diagnostic imaging plays an important role in its diagnosis [5].

Both CT and MRI are useful for detecting frankly subluxated or dislocated peroneal tendons by revealing the position of the tendons relative to the fibular groove [6]. However, neither of these static imaging techniques can reveal subluxation that is episodic [7]. In acute subluxation or dislocation, spontaneous reduction usually occurs [3, 7]. Furthermore, in chronic recurrent subluxation, the peroneal tendons are often in the correct anatomic position at rest and may only subluxate intermittently when specific biomechanical stresses or foot positions are used [7]. Thus, a real-time imaging technique would be the most appropriate method by which to diagnose peroneal tendon subluxation.

Sonography is well suited to tendon imaging because of its high spatial resolution and superb depiction of tendon architecture. In this study, we explore the ability of sonography to display abnormalities in patients in whom peroneal tendon subluxation is suspected clinically.


Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
From June 2001 to June 2003, 13 consecutive patients (10 females and three males; mean age, 30.4 years; age range, 16–66 years) were examined by the same orthopedic surgeon. The surgeon believed that these patients had peroneal tendon subluxation on the basis of the following criteria: a history of a nonresolving ankle sprain; tenderness posterior to the distal fibula; reproduction of pain by active dorsiflexion and eversion of the ankle; and, in nine of the 13 patients, a palpable "click" felt over the posterior fibula in the region of the peroneal tendons on active dorsiflexion and eversion of the ankle. All patients were subsequently scanned by a sonologist with 10 years of experience in musculoskeletal sonography. Scans were obtained with a linear array transducer with peak frequency of 13 MHz (Elegra, Siemens) or 12 MHz (HDI 5000, Philips Medical Systems) and standard acoustic coupling gel. The patients were examined in the seated position with their feet hanging off the side of the stretcher. The ultrasound probe was placed directly behind the lateral malleolus, and the peroneus longus and peroneus brevis tendons were identified axially within the fibular groove and were followed up to the level of the musculotendinous junctions. The tendons were then followed back down to and below the lateral malleolus: the peroneus brevis to its insertion on the base of the fifth metatarsal bone and the peroneus longus to its entry into the plantar tunnel. Corresponding longitudinal images were obtained by turning the transducer orthogonal in relation to the axial plane. In five patients in whom the findings were subtle, comparison was made with the contralateral side for confirmation of peroneal tendon subluxation.

At rest, the tendons were evaluated by the sonologist for evidence of tendinitis, flattening, and tears. Tendinitis was identified as focal or diffuse thickening of the affected tendon or as heterogeneity of the tendon echotexture. The presence of tendon thickening was determined by subjectively comparing calibers of the peroneus longus and peroneus brevis tendons at and slightly below the level of the lateral malleolus. At this location, the tendons should normally be comparable in their cross-sectional areas, with the peroneus longus tendon being minimally larger. When the cross-sectional areas of the tendons were clearly discrepant, the judgment was then made whether the larger tendon was thickened, the smaller tendon was thinned, or both. Tears were defined as linear hypoechoic foci within the tendons and were characterized, when present, as longitudinal or transverse.

For dynamic scanning, the foot was dorsiflexed and everted both passively and actively from the neutral position. During these maneuvers, the probe was positioned in the axial plane, imaging the peroneus longus and peroneus brevis tendons at the level of the fibular groove. Subluxation observed by the sonologist was of two types: either one or both of the peroneal tendons subluxated anteriorly over the lateral malleolus (i.e., typical subluxation) or the peroneus longus and peroneus brevis tendons showed abnormal motion relative to each other such that the two tendons temporarily reversed their normal anteroposterior relationship (i.e., retrofibular intrasheath subluxation).

Of the 13 patients who underwent sonographic evaluation for peroneal tendon subluxation, 12 had positive findings and subsequently underwent surgical repair. The patient with normal sonographic findings was followed clinically, and her symptoms resolved without surgical intervention. At surgical exposure, the peroneal tendons were observed for subluxation. If subluxation was present, fibular groove deepening and repair and reinforcement of the peroneal retinaculum were undertaken. In addition, the surgeon noted any tendinitis, flattening, or tears of the peroneal tendons. The tendons were repaired if a tear was noted.

We noted whether peroneal tendon subluxation was described as being present or absent on the sonography reports of the 13 patients who underwent sonography. In addition, each of the peroneus longus and peroneus brevis tendons was assessed on sonograms as normal, tendinotic, flattened, or torn (split) either longitudinally or horizontally. The same types of information were drawn from the surgical reports of the 12 patients who underwent surgical repair. Data were transferred to a computer spreadsheet for statistical analysis. Sonographic findings were compared with surgical findings for diagnosis of subluxation, tendon tears, or other abnormalities.

Asymptomatic volunteers with no history of major ankle injury served as a control group. Twenty ankles in 10 volunteers (eight women and two men; mean age, 30.9 years; age range, 24–53 years) were scanned using the identical sonographic equipment and techniques used to image the symptomatic patients.

Institutional review board approval was obtained for the retrospective analysis of the sonography reports of the 13 patients who underwent sonography and the surgical reports of the 12 patients who underwent surgical repair. Once institutional review board approval was granted, these reports were retrieved from the patient information system at our teaching hospital and used as described.


Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
On sonography, none of the peroneal tendons was subluxated at rest. Of the 12 patients with dynamic sonographic findings of peroneal subluxation (Figs. 1A, 1B and 2A, 2B), all were subsequently found to have subluxation at surgery. Ten patients had typical subluxation, and two patients had retrofibular intrasheath subluxation. The positive predictive value of dynamic sonography for peroneal tendon subluxation was therefore 100%. Because sonographic depictions of subluxation determined which patients went to surgery, overall sensitivity and accuracy of dynamic sonography could not be calculated.



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  		Fig. 1A. —20-year-old man with typical subluxation of right peroneal tendon. Axial sonogram obtained with affected ankle in neutral position shows peroneus longus (L) and peroneus brevis (B) tendons in normal relationship posterior to distal fibula (F).

 


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  		Fig. 1B. —20-year-old man with typical subluxation of right peroneal tendon. Axial sonogram obtained with affected ankle dorsiflexed and everted shows that peroneus longus (L) and peroneus brevis (B) tendons have subluxated anteriorly and now lie superficial relative to distal fibula (F).

 


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  		Fig. 2A. —20-year-old woman with retrofibular intrasheath subluxation of left peroneal tendon. Axial sonogram obtained with affected ankle in neutral position shows peroneus longus (L) and peroneus brevis (B) tendons in normal relationship posterior to distal fibula (F). Note slight flattening of peroneus brevis tendon when at rest.

 


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  		Fig. 2B. —20-year-old woman with retrofibular intrasheath subluxation of left peroneal tendon. Axial sonogram obtained with affected ankle dorsiflexed and everted shows that peroneus longus (L) and peroneus brevis (B) tendons have reversed their normal anteroposterior relationship, although they are still located behind distal fibula (F).

 

Sonography revealed that five patients had peroneus brevis tendon tears (all of which were longitudinal [Fig. 3]) and seven patients had no tears. Identical findings were reported at surgery. Therefore, for the 12 patients who underwent surgery, the sensitivity, specificity, and accuracy of sonography for predicting tears of the peroneus brevis tendon were all 100%. In one case, tendinitis of the peroneus brevis tendon was not seen on sonography and was later found at surgery, and in another case, flattening of the peroneus brevis tendon was identified on sonography but not found at surgery. However, all five longitudinal tears seen on sonography were confirmed intraoperatively, with no false-positive or false-negative findings.



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  		Fig. 3. —17-year-old girl with severe subluxation of left peroneal tendon. Axial sonogram obtained with affected ankle dorsiflexed and everted shows that peroneus brevis (B) tendon has torn longitudinally into two parts, with more anterior part (arrow) subluxated over fibula (F). L = peroneus longus tendon.

 

Similarly, sonography revealed a peroneus longus tendon tear in one patient and no tears in 11 patients, and identical findings were reported at surgery. Therefore, for the patients who underwent surgery, sensitivity, specificity, and accuracy of sonography in predicting tears of the peroneus longus tendon were 100%. Two cases of peroneus longus tendinitis identified on sonography were not found at surgery, and, conversely, two cases of tendinitis seen at surgery had not been noted on sonography reports.

In the asymptomatic control subjects, four of the 20 ankles examined on sonography showed peroneal tendon subluxation; in two ankles, typical subluxation was noted, and in the other two ankles, retrofibular intrasheath subluxation was seen. In 16 of the 20 ankles, no findings of peroneal tendon subluxation were observed. None of the 20 ankles showed signs of tendinitis, tendon flattening, or tendon tears.


Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The peroneus longus and peroneus brevis tendons function primarily as evertors of the foot and dynamic stabilizers of the lateral ankle [3, 6, 8, 9]. Additionally, these tendons allow plantar flexion of the ankle joint as well as pronation and abduction of the foot [3, 8–10]. The muscles descend in the lateral compartment of the leg and become tendons before reaching the ankle joint [1]. The peroneus brevis tendon descends anteromedially to the peroneus longus tendon, and both tendons pass through the common peroneal synovial sheath approximately 4 cm proximal to the lateral malleolus [3, 8]. This synovial sheath passes through a fibroosseous tunnel that is stabilized posterolaterally by the superior peroneal retinaculum; medially by the posterior talofibular ligament, calcaneofibular ligament, and posteroinferior tibiofibular ligament; and anteriorly by the fibular groove [3, 6, 8, 11, 12]. The major stabilizing structure preventing peroneal subluxation is the superior peroneal retinaculum, which converts the fibular groove into a fibroosseous tunnel [1, 3, 10, 13]. As the two tendons descend into the fibular groove, the peroneus brevis tendon commonly assumes an anterior (as opposed to anteromedial) position relative to the peroneus longus tendon [6]. Once the tendons pass distal relative to the superior peroneal retinaculum, they are again enveloped by individual tendon sheaths [3, 14].

Peroneal subluxation usually involves one or both peroneal tendons moving anteriorly over the lateral malleolus [3, 15]. However, a snapping may be palpated or heard within the common peroneal tendon sheath, with no apparent anterior subluxation of the tendons [14]. In these cases, the tendons subluxate on each other, temporarily reversing their relative positions but remaining behind the lateral malleolus. This condition has been referred to as retrofibular intrasheath subluxation [4].

The literature cites many predisposing factors for peroneal tendon subluxation such as a flat or convex fibular groove, but most cases of subluxation in adults and children are posttraumatic in origin [1, 3, 5, 9, 11, 14, 16]. Peroneal tendon subluxation may be either acute or chronic recurrent [3]. Among the cases of acute peroneal tendon subluxation reported in the literature, more than 90% were athletic injuries from skiing, ice skating, running, basketball, soccer, gymnastics, tennis, or football [3, 8, 12, 14]. Patients often report hearing a snapping or popping sound at the time of injury, and their condition is often misdiagnosed as an inversion ankle sprain, delaying appropriate treatment [1, 2, 8]. Generally, peroneal tendon subluxation causes retromalleolar swelling and ecchymosis, with pain along the posterior lip of the fibula [1, 8, 14]. The mechanism of injury in acute subluxation is a sudden passive dorsiflexion and eversion, followed by a reflexive contraction of the peroneus longus and peroneus brevis tendons that disrupts the superior peroneal retinaculum or its attachments [1, 3, 8, 14].

Chronic recurrent peroneal tendon subluxation often presents in patients who have a history of recurrent inversion ankle sprains and lateral ankle instability, or it may result from an undiagnosed acute subluxation [1, 3, 12]. Patients with chronic recurrent peroneal tendon subluxation report a snapping or popping sensation and lateral ankle pain that are associated with the repeated episodes of subluxation [14]. These episodes occur when the foot is dorsiflexed and everted. In patients with chronic recurrent subluxation, especially subluxation that results from chronic inversion ankle sprains, the development of a lax and incompetent superior peroneal retinaculum leads to repeated episodes of subluxation [3, 11, 17]. It is known that longitudinal tears of the peroneal tendons, especially the peroneus brevis, may occur progressively in a high percentage of patients with recurrent peroneal tendon subluxation [6, 10, 17]. In the so-called peroneal splits syndrome, repetitive peroneal tendon subluxation leads to hypertrophy of the peroneus longus tendon. Additionally, there is longitudinal tearing, with eventual bisection, of the peroneus brevis tendon, extending from just distal relative to the lateral malleolus up to 2–5 cm proximally [3, 18]. The peroneus longus tendon, which is posterior to the peroneus brevis tendon, is protected by it from mechanical attrition [11].

Surgical repair is increasingly being recognized as the treatment of choice for both acute and chronic recurrent peroneal tendon subluxation [4]. Given that clinical diagnosis is often difficult, particularly in the acute setting, imaging has a role in diagnosing this condition so that proper and prompt surgical repair can be initiated.

The literature describes the use of CT and MRI in the diagnosis of peroneal tendon subluxation. Rosenberg et al. [9] showed the value of CT in assessing rupture, impingement, tenosynovitis, and dislocation of ankle tendons. MRI offers better soft-tissue resolution than CT and is better for revealing subtle longitudinal splits in the peroneal tendons [3, 6, 14]. Both CT and MRI can reveal frankly subluxated or dislocated peroneal tendons by depicting the anterolateral position of the tendons relative to the fibular groove [6]. However, in acute and chronic recurrent subluxation, the tendons often are not subluxated when at rest, and these static imaging techniques cannot reliably document episodic or transient subluxation [7]. The ideal imaging technique for documenting subluxation would allow the status of the peroneal tendons to be monitored while the patient dorsiflexed and everted the ankle [7, 18]. Sonography is such a technique, but there are few reports on the use of sonography in assessing peroneal subluxation [8, 14].

In this study, we have shown in a small patient population that sonography has a 100% positive predictive value for revealing peroneal subluxation. Sonography also appears to be accurate in revealing longitudinal tears in both the peroneus brevis and peroneus longus tendons.

Our study has definite limitations. First, the small sample size limits the power of our statistical analysis. Bias may have been introduced because patients who underwent sonography were those in whom peroneal tendon subluxation was already clinically suspected. A randomized, controlled study would be ideal but in practice would be difficult to perform because our surgeon uses sonographic findings to determine which patients should undergo surgery. However, we did show that of the 20 asymptomatic ankles we evaluated, 16 had no peroneal tendon subluxation, and none showed signs of tendinitis, tendon flattening, or tendon tears.

In summary, we have shown that sonography is an effective tool for diagnosing peroneal tendon subluxation as well as longitudinal tears of the peroneal tendons. Compared with static techniques such as CT and MRI, we consider sonography the test of choice for imaging peroneal subluxation.


References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Butler BW, Lanthier J, Wertheimer SJ. Subluxing peroneals: a review of the literature and case report. J Foot Ankle Surg1993; 32:134 –139[Medline]
  2. Hutchinson BL, Gustafson LS. Chronic peroneal tendon subluxation: new surgical technique and retrospective analysis. J Am Podiatr Med Assoc 1994;84:511 –517[Abstract]
  3. Clarke HD, Kitaoka HB, Ehman RL. Peroneal tendon injuries. Foot Ankle Int1998; 19:280 –288[Medline]
  4. McConkey JP, Favero KJ. Subluxation of the peroneal tendons within the peroneal tendon sheath: a case report. Am J Sports Med 1987;15:511 –513[Free Full Text]
  5. Hutchinson BL, O'Rourke EM. Tibialis posterior tendon dysfunction and peroneal tendon subluxation. Clin Podiatr Med Surg1995; 12:703 –723[Medline]
  6. Mota J, Rosenberg ZS. Magnetic resonance imaging of the peroneal tendons. Top Magn Reson Imaging1998; 9:273 –285[Medline]
  7. Shellock FG, Feske W, Frey C, Terk M. Peroneal tendons: use of kinematic MR imaging of the ankle to determine subluxation. J Magn Reson Imaging 1997;7:451 –454[Medline]
  8. Safran MR, O'Malley DF Jr, Fu FH. Peroneal tendon subluxation in athletes: new exam technique, case reports, and review. Med Sci Sports Exerc 1999;31[suppl]:S487 –S492[Medline]
  9. Rosenberg ZS, Feldman F, Singson RD. Peroneal tendon injuries: CT analysis. Radiology1986; 161:743 –748[Abstract/Free Full Text]
  10. Tjin A, Ton ER, Schweitzer ME, Karasick D. MR imaging of peroneal tendon disorders. AJR1997; 168:135 –140[Free Full Text]
  11. Yao L, Tong DJ, Cracchiolo A, Seeger LL. MR findings in peroneal tendonopathy. J Comput Assist Tomogr1995; 19:460 –464[Medline]
  12. Omey ML, Micheli LJ. Foot and ankle problems in the young athlete. Med Sci Sports Exerc1999; 31[suppl]:S470 –S486[Medline]
  13. Karlsson J, Eriksson BI, Sward L. Recurrent dislocation of the peroneal tendons. Scand J Med Sci Sports1996; 6:242 –246[Medline]
  14. Scanlan RL, Gehl RS. Peroneal tendon injuries. Clin Podiatr Med Surg 2002;19:419 –431[Medline]
  15. Davis WH. Traumatic peroneal tendon instability. (comment) Am J Sports Med1997; 25:587[Free Full Text]
  16. Szczukowski M Jr, St. Pierre RK, Fleming LL, Somogyi J. Computerized tomography in the evaluation of peroneal tendon dislocation: a report of two cases. Am J Sports Med1983; 11:444 –447[Abstract/Free Full Text]
  17. Bonnin M, Tavernier T, Bouysset M. Split lesions of the peroneus brevis tendon in chronic ankle laxity. Am J Sports Med1997; 25:699 –703[Abstract/Free Full Text]
  18. Schweitzer ME, Eid ME, Deely D, Wapner K, Hecht P. Using MR imaging to differentiate peroneal splits from other peroneal disorders. AJR 1997;168:129 –133[Abstract/Free Full Text]

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