0198-0211/92/1307-0413$03.00/0 FOOT & ANKLE Copyright © 1992 by the American Orthopaedic Foot and Ankle Society, Inc.
The Dynamics of Peroneus Brevis Tendon Splits: A Proposed Mechanism Technique of Diagnosis, and Classification of Injury , Mark Sobel, M. D.,. Mark J. Geppert, M.D.,t Eric J. Olson, M.D.,+ Walther H. O. Bohne, M.D.,§ and Steven P. Arnoczky, D.V.M.II New York, New York, Somersworth, New Hampshire, Washington, D.C., and East Lansing, Michigan
INTRODUCTION
ABSTRACT 16
The etiology of peroneus brevis splits is unclear. ,24 Because longitudinal splits in the peroneus brevis tendon do not necessarily effect the integrity or strength of the tendon, it is difficult to ascertain whether or not injury to the peroneus brevis tendon is present. Recent clinical, anatomic, and histologic reports have suggested that the split develops from prolonged mechanical attrition within the fibular groove as a result of ankle trauma with resultant lateral ankle instability and incompetency of the superior peroneal retinaculum with resultant subluxation of the peroneal tendons. 15 ,17 ,22 - 25 This cascade of events may result in splitting of the peroneus brevis tendon. The purpose of this paper was to report the investigation of the mechanism by which peroneus brevis splits develop, to describe a technique of diagnosis, and to propose a classification of injury. Peroneus brevis splits are the result of a dynamic mechanical insult at the fibular groove. Laxity of the superior peroneal retinaculum combined with peroneus longus mechanical compression causes the peroneus brevis to splay out and eventually split over the sharp posterior edge of the fibula. Anatomic factors, such as a shallow fibular groove (congenital convex groove) or the presence of an anomalous low-lying peroneus brevis muscle belly or peroneus quartus tendon,4,7,25 may also playa role in this mechanism by interfering with the competence of the superior peroneal retinaculum.
The entity of peroneus brevis tendon splits has received little attention until recently.' ,5,9-13 The early work of Meyers11 described the lesion as "attritional" or secondary to wear and tear within the fibular groove. Since then, Sammarco" and DiRaimondo2,15 and Speer and Bassett" reported this lesion in a young athletic population who presented with lateral ankle pain and symptoms of ankle instability. Their report supports a more traumatic (repetitive ankle sprain) etiology for the lesion based upon a history of trauma and young age. In cadaveric dissections performed by the authors in mostly elderly specimens, the lesion was found to be present in a significant number of ankles without evidence of trauma or ligamentous injury.17,18,23 Furthermore, histologic evaluation of these splits has shown evidence of chronic wear and tear effects on the collagen with the presence of sufficient vascularity to mount a reparative healing response.":" In an attempt to elucidate the pathogenesis of this lesion, the authors studied the dynamics of simulated peroneal contraction and tendon movement at the fibular groove in cadaveric specimens with peroneus brevis tendon splits. These studies suggest a mechanical etiology of peroneus brevis tendon splits that explains the initiation, propagation, and permanance of peroneus brevis splits in both an elderly and young population. Our understanding of the dynamic etiology of peroneus brevis tendon splits suggests that a recreation of the retaining force created by the superior peroneal retinaculum (SPR) would accentuate the patient's pain when a peroneus brevis tendon split is present (i.e., the Peroneal Tunnel Compression Test). This can be done by exerting pressure against the tightening tendons at the level of the SPR. Careful palpation of the posterior border of the fibula, at the origin of the SPR, while the patient everts the involved ankle against resistance, allows detection of snapping, popping, or partial tendon
* Orthopaedic Resident, The Hospital for Special Surgery, New York, New York 10021. To whom requests for reprints should be addressed at c/o Roger A. Mann, M.D., 237 Estudillo Ave., San Leandro, California 94578. t Private Practice, Orthopaedic and Trauma Surgeons, Somersworth, New Hampshire 03878. :j: Staff Orthopaedic Surgeon, Major, MC USA, Walter Reed Army Medical Center, Washington, DC 20307-5001. § Clinical Associate Professor of Orthopaedics, The Hospital for Special Surgery. II Director, Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824-1314.
413
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
414
SOBEL ET AL.
Foot & Ankle/Vol. 13, No. 7/September 1992
subluxation that accompanies the pain experienced by patients with symptomatic longitudinal splits of their peroneus brevis tendon. This correlated with our understanding of the pathomechanics leading to longitudinal splits of the peroneus brevis tendon, and may be a helpful aid in the clinical diagnosis of peroneus brevis splits. We have used this test successfully with operative confirmation in seven cases. We have also sought to classify the lesion based on the extent of the split. MATERIALS AND METHODS
Fig. 1. Photograph showing the position of the examiner's thumb spanning the posterior ridge of the fibula to the calcaneus and compressing the peroneal tendons and superior peroneal retinaculum as the foot is actually moved from a plantarflexed, inverted position to a dorsiflexed and everted position.
Since the prevalence of peroneus brevis splits is relatively common in cadaveric specimens, we have been able to dynamically demonstrate the lesion by (1) removing the skin and subcutaneous tissue from the lateral ankle, (2) exposing the peroneus longus and peroneus brevis tendons from the upper third of the tibia down to the level of the fifth metatarsal, (3) mimicking contraction of the peroneus longus muscle by manually tensing the peroneus longus tendon while everting the hindfoot and midfoot, (4) performing item 3 before and after releasing the superior peroneal retinaculum, and, finally, (5) inspecting the peroneus brevis tendon in the fibular groove. Photographs, illustrations, and a videotape were taken of the lateral ankle in three positions: (1) at rest (no eversion of the foot and no pull on the peroneus longus tendon), (2) moderate pull on the peroneus longus, moderate manual eversion of the hindfoot and midfoot, and (3) maximal pull on the peroneus longus, maximal manual eversion of the hindfoot and midfoot. The above sequence was performed on 15 specimens of which five had peroneus brevis splits. The specimens were fresh frozen and included both sexes. All were from adults. Peroneal Tunnel Compression Test
Fig. 2. Photograph showing that, alternatively, the examiner may place the index, middle, and long fingertips directed posteriorly over the posterior edge of the fibula while resting ankle eversion with the opposite hand.
The patient is asked to sit on the end of an examining table with the knee of the involved extremity bent to 90 0 and the foot and ankle relaxed in a plantarflexed position. Next, the examiner places his or her thumb over the superior peroneal retinaculum from the posterior ridge of the fibula to the calcaneus and presses gently downward on the peroneal tendons while at rest. Then the patient is asked to. forcefully dorsiflex and evert the foot and ankle while the examiner holds his or her thumb firmly over the superior peroneal retinaculum (Fig. 1). A positive test is marked by a recreation of the patient's pain. Crepitus or squeaking of the involved tendons (wet leather sign) may be palpable." Alternatively, the examiner may place the index, middle, and long fingertips directed posteriorly over the posterior edge of the fibula, while resisting ankle eversion with the opposite hand (Fig. 2). Additional findings may
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & AnkJejVoJ. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
415
Fig. 3. A. This photograph demonstrates the relationship between the peroneus brevis, peroneus longus, and posterior edge of the fibula, with no pull on the peroneus longus and the foot in neutral alignment. B, This photograph demonstrates the same relationship as Figure 1A from a posterior view. C, This illustration further characterizes the photograph in Figure 1A. D, This illustration shows a cross-section of the ankle (illustrated in Fig. 1B) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
416
SOBEL ET AL.
Foot & AnklejVol. 13, No. 7/September 1992
Fig. 4. A, This photograph demonstrates the relationship between the peroneus longus and peroneus brevis, with moderate pUll on the peroneus longus and moderate eversion of the foot. B, This photograph demonstrates the same relationship as Figure 2A from a posterior view. C, This illustration further characterizes the photograph in Figure 2A. 0, This illustration shows a cross-section of the ankle (illustrated in Fig. 28) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
417
Fig. 5. A, This photograph shows the relationship between the peroneus longus and peroneus brevis, with maximal pull on the peroneus longus and maximal eversion of the foot. B, This photograph demonstrates the same relationship as shown in Fig. 3A from a posterior view. C, This illustration further characterizes the photograph in Figure 3A. D, This illustration shows a cross-section of the ankle (illustrated in Fig. 38) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
418
SOBEL ET AL.
Foot & AnklefVol. 13, No. 7/September 1992
Fig. 7. This photograph demonstrates a grade I peroneus brevis split: splayed out.
Fig. 6. A, This photograph reveals a peroneus brevis split with the posterior edge of the fibula protruding through the split. B, This photograph demonstrates the same relationship seen in Figure 4A from a posterior view.
TABLE 1 Grading Scale for Peroneus Brevis Splits Grade I Grade II Grade III Grade IV
Splayed out (Fig. 7) Partial thickness split 2 cm
be a jumping sensation, triggering or clicking of the peroneal tendons within the groove, or a sensation of the anterior half of the peroneus brevis tendon attempting to subluxate over the sharp posterior ridge of the fibula.
RESULTS
In the specimens that had peroneus brevis splits, the pull of the peroneus longus with eversion of the foot always demonstrated compression of the peroneus brevis by the peroneus longus at the fibular groove. The flattened peroneus brevis tendon splayed out, with the anterior portion of the tendon slipping forward, out of the groove, and over the sharp posterior edge of the fibula. Wedged against the knife-like posterior edge of the fibula, all dissected peroneus brevis splits were found to occur at this point. The sequence is accentuated when the superior peroneal retinaculum is released because this removes the only structure that holds the peroneus brevis in the groove as the peroneus longus tightens down against it (Figs. 3-6). The lesion created in the peroneus brevis is variable in both length and thickness (partial versus full); accordingly, the authors propose a grading scale to quantify the extent of split lesions ranging from simple splaying out of the
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
419
Fig. 8. This photograph demonstrates a grade II peroneus brevis split: partial thickness 2 em.
tions of elderly specimens as well as in patients with subluxating peroneal tendons.':" Anatomic factors can be implicated in contributing to incompetence of the superior peroneal retinaculum. Peroneus brevis splits with subluxating peroneal tendons in the presence of an anomalous low-lying peroneus brevis muscle belly causing a crowding phenomenon within the fibular groove have been reported.":" Hammerschlag and Goldner?suggest that an encroachment phenomenon develops within the fibular groove by an anomalous extra peroneus brevis that leads to subluxation of the peroneal tendons. Other congenital abnormalities of the peroneal tendons have been well described, all potentially affecting the competence of the restraints at the fibular groove. 14,22.25 Peroneal tendon subluxation is associated with the creation of peroneus brevis splits. Any incompetence of the peroneal restraints that allows the flattening and migration of the anterior portion of the peroneus brevis out of the fibular groove can result in a split. The authors
have also looked at the questionable role of hypovascularity as an etiology of peroneus brevis splits, and these studies have shown that a sufficient supply of blood to the peroneus brevis tendon does exist at the split.21 This is in agreement with the ample vascularity seen in histologic specimens." The compression of the peroneus brevis tendon by the wedge-like peroneus longus prevents repair mechanically and dynamically. This paper describes a new clinical test to aid in the diagnosis of peroneus brevis splits. Because longitudinal splits in the peroneus brevis do not necessary affect the integrity or strength of the tendon, it is difficult to ascertain whether or not an injury to the peroneus brevis tendon is present. The mechanism of peroneus brevis splits is likely secondary to a dynamic insult to the tendon as it subluxates out over the posterior ridge of the fibula1?,19,22-24,26 and secondary to peroneus longus tendon compression and SPR laxity. The SPR may become partially attenuated and/or detached from the posterior border of the fibula, either from primary injury to the retinaculum or due to repetitive loading of the peroneus brevis against it. This creates a more capacious peroneal tunnel, but allows the peroneus brevis tendon to subluxate laterally over the sharp posterior ridge of the fibula. This ridge may be blunt or sharp and is more variable from individual to individual. It appears from our cadaveric work that the presence of a sharp posterior ridge, as opposed to a rounded or flat posterior ridge, enhances the ability of the fibula to split the peroneus brevis tendon. Factors that contribute to "overcrowding" within the peroneal tendon sheath and fibular groove include tenosynovttis,? peroneus longus or brevis tendon hypertrophy secondary to attrition, anomalously distal muscle insertion into the peroneus brevis tendon.v" and the presence of a peroneus quartus tendon." During resisted eversion, the peroneus longus tendon compresses against the peroneus brevis tendon anteriorly. If the SPR fails to contain the peroneus brevis tendon, a portion of it subluxates laterally, often accompanied by a painful click. The subluxated peroneus brevis tendon may become split as it rides over the posterolateral edge of the fibula. Palpation over the peroneal tunnel thus permits detection of partial tendon subluxation as well as compresses the peroneal tunnel. Compression of the tunnel produces pain caused by tenosynovitis, which may accompany longitudinal splits of the peroneus brevis tendon. It makes sense that the recreation of a firm superior peroneal retinaculum that prohibits this subluxation will exacerbate pain. Clinical findings can be supported by perpendicular axial cuts at the level of the posterior ridge of the fibula on magnetic resonance imaging or CT evaluation, which has been shown to identify this
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
lesion quite well." In cases refractory to conservative treatment, exploration of the peroneal sheath is recommended. If a peroneus brevis split is found upon exploration, debridement of the tendon edges and repair of the peroneus brevis split, in addition to tubing of the tendon and reefing of the superior peroneal retinaculum, seem warranted. 19 ,20 In addition, when present, the sharp posterior ridge of the fibula can be removed as well as. This both removes a possible insult to the tendon and creates an excellent bony bed for the SPR advancement and repair." Furthermore, any additional overcrowding within the peroneal tunnel by the presence of an anomalous low-lying peroneus brevis muscle or the presence of a peroneus quartus tendon should be removed, thus decompressing the peroneal tunnel. In conclusion, the results of this study demonstrate that peroneus brevis splits are common dynamic lesions that are caused by a combination of (1) superior peroneal retinacular laxity, either traumatic or degenerative; (2) a shallow fibular groove or anomalous muscles or tendons leading to incompetence of the superior peroneal retinaculum; (3) peroneus longus compression; and (4) a sharp posterior edge of the fibula. This mechanical etiology explains why the lesion can be seen in young athletic patients with subluxating peroneal tendons and/or lateral ankle instability, as well as in the elderly with no identifiable risk factors.":" A grading scale (based on cadaveric findings) is described to further clarify the extent of the peroneus brevis split, which may have clinical implications in future reports on surgical treatment for this entity. Because this is a cadaveric study, this classification cannot give any prognosis. It serves merely as a method for surgeons to group lesions so that, in the future, classification, treatment, and outcome may be uniformly reported.
REFERENCES 1. Arrowsmith, S.R., Fleming, L.L., and Allman, F.L.: Traumatic dislocations of the peroneus tendons. J. Sports Med., 11:142146,1983. 2. DiRaimondo, C.: Overuse conditions of the foot and ankle. In Foot and Ankle Manual. A.O.F.A.S., Sammarco, G.J. (ed.), Philadelphia, Lea & Febiger, 1991, Ch. 21, p. 266. 3. Eckert, W.R., and David, E.A., Jr.: Acute rupture of the peroneal retinaculum. J Bone Joint Surg., 58A:670-673, 1976. 4. Edwards ME.: The relations of the peroneal tendons to the fibula, calcaneus, and cuboideum. Am. J. Anat., 42:213-253, 1928. 5. Evans, J.D.: Subcutaneous tear of the tendon of peroneus longus. J. Bone Joint Surg., 48B:507-509, 1966.
PERONEUS BREVIS TENDON SPLITS
421
6. Geppert, M.J., Sobel, M., and Davis, W.H.: Encroachment at the fibular groove secondary to anomalous low-lying peroneus brevis muscle belly: an anatomic study and report of two cases. Presented at the A.O.FAS. Annual Summer Meeting, Napa California, July 1992. Clin. Anat. (in press). 6a. Geppert, M.J., Sobel, M., and Bohne, W.H.O.: The mechanism of superior peroneal retinacular laxity secondary to lateral ankle instability: an anatomic study. Presented at the A.O.FAS. Annual Summer Meeting, Napa, California, July 1992. 7. Hammerschlag, W.A., and Goldner, J.L.: Chronia peroneal tendon subluxation produced by an anomalous peroneus brevis: a case report and review of the literature. Foot Ankle, 10:45-47, 1989. 8. Jones, D.C.: Bucket handle tears of the peroneus brevis tendon. Presented at the American Orthopaedic Foot and Ankle Society, Summer Meeting, Sante Fe, NM 1987. 9. Larsen, E.: Longitudinal rupture of the peroneus brevis tendon. J. Bone Joint Surq.; 69B:340-341, 1987. 10. Martens, M.A., Noyez, J.F., and Mulier, J.C.: Recurrent dislocation of the peroneal tendons. Result of rerouting the tendons under calcaneofibular ligament. Am. J. Sports Med., 14:148150,1986. 11. Meyers, A.W.: Further evidence of attrition in the human body. Am. J. Anat., 34:241-267,1924. 12. Munk, R.L., and Davis, P.H.: Longitudinal ruptures of the peroneus brevis tendon. J. Trauma, 16:803-806,1976. 13. Purnell, M.L., Drummond, D.S., Engbar, W.O., and Breed, A.L.: Congenital dislocation of the peroneal tendons in the calcaneovalgus foot. J. Bone Joint Surg., 65B:316, 1983. 14. Sammarco, G.J., and Brainard, B.J.: A symptomatic anomalous peroneus brevis in a high jumper: a case report. J. Bone Joint Surg., 73A:131-133, 1991. 15. Sammarco, G.J., and DiRaimondo, C.V.: Chronic peroneus brevis tendon lesions. Foot Ankle, 9:163-170,1989. 16. Sammarco, J.: Letter to the editor re: longitudinal attrition of the peroneus brevis tendon in the fibular groove: an anatomic study. Foot Ankle, 11:248, 1991. 17. Sobel, M., Bohne, W.H.O., DiCarlo, E., and Collins, L.: Longitudinal splitting of the peroneus brevis tendon: an anatomic and histologic study of cadaveric material. Foot Ankle, 12:165-170, 1991. 18. Sobel, M., Bohne, W.H.O., Markisz, J., and Collins, L.: Cadaver correlation of peroneal tendon changes with magnetic resonance imaging. Foot Ankle, 11:384-388, 1991. 19. Sobel, M., Geppert, M., and Warren, R.F.: Chronic ankle instability as a cause of peroneal tendon injury. Clin. Orthop. (in press). 20. Sobel, M., and Geppert, M.J.: Repair of concomitant lateral ankle ligament instability and peroneus brevis splits through a posteriorly modified Brostrom Gould. Foot Ankle, 13:224-225, 1992. 21. Sobel, M., Geppert, M.J., Bohne, W.H.O., and Hannafin, J.A.: The microvascular anatomy of the peroneal tendons. Foot Ankle (in press). 22. Sobel, M., Levy, M., and Bohne, W.H.O.: Congenital variations of the peroneus quartus muscle: an anatomic study. Foot Ankle, 11:81-89, 1990. 23. Sobel, M., Levy, M. E., and Bohne, W.H.O.: Longitudinal attrition of the peroneus brevis tendon in the fibular groove: an anatomic study. Foot Ankle, 11:124-128,1990. 24. Sobel, M., Levy, M.E., and Bohne, W.H.O.: Longitudinal attribution of the peroneus brevis tendon in the fibular groove: an
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
422
SOBEL ET AL.
Foot & AnklejVol. 13, No. 7 jSeptember 1992
anatomic study. Letter to the editor: author's response. Foot Ankle, 11:249-251, 1991. 25. Sobel, M., O'Brien, S.J., and Bohne, W.H.O.: Longitudinal attrition of the peroneus brevis tendon secondary to an encroachment phenomenon within the peroneal tendon sleeve: a report of two cases. Acta Orthop. Scand. (in press). 26. Sobel, M., Warren, R.F., and Brourman, S.: Lateral ankle insta-
bility associated with dislocation of the peroneal tendons treated by a modified Chrisman-Snook procedure: a new technique and review of the literature. Am. J. Sports Med., 18:539-543, 1990. 27. Speer, K.S., and Bassett, F.: Chronic tears of the peroneal tendons. Presented at the annual American Academy of Sports Medicine Summer Meeting, Orlando, FL, 1991. Am. J. Sports Med. (in press).
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
The Dynamics of Peroneus Brevis Tendon Splits: A Proposed Mechanism Technique of Diagnosis, and Classification of Injury , Mark Sobel, M. D.,. Mark J. Geppert, M.D.,t Eric J. Olson, M.D.,+ Walther H. O. Bohne, M.D.,§ and Steven P. Arnoczky, D.V.M.II New York, New York, Somersworth, New Hampshire, Washington, D.C., and East Lansing, Michigan
INTRODUCTION
ABSTRACT 16
The etiology of peroneus brevis splits is unclear. ,24 Because longitudinal splits in the peroneus brevis tendon do not necessarily effect the integrity or strength of the tendon, it is difficult to ascertain whether or not injury to the peroneus brevis tendon is present. Recent clinical, anatomic, and histologic reports have suggested that the split develops from prolonged mechanical attrition within the fibular groove as a result of ankle trauma with resultant lateral ankle instability and incompetency of the superior peroneal retinaculum with resultant subluxation of the peroneal tendons. 15 ,17 ,22 - 25 This cascade of events may result in splitting of the peroneus brevis tendon. The purpose of this paper was to report the investigation of the mechanism by which peroneus brevis splits develop, to describe a technique of diagnosis, and to propose a classification of injury. Peroneus brevis splits are the result of a dynamic mechanical insult at the fibular groove. Laxity of the superior peroneal retinaculum combined with peroneus longus mechanical compression causes the peroneus brevis to splay out and eventually split over the sharp posterior edge of the fibula. Anatomic factors, such as a shallow fibular groove (congenital convex groove) or the presence of an anomalous low-lying peroneus brevis muscle belly or peroneus quartus tendon,4,7,25 may also playa role in this mechanism by interfering with the competence of the superior peroneal retinaculum.
The entity of peroneus brevis tendon splits has received little attention until recently.' ,5,9-13 The early work of Meyers11 described the lesion as "attritional" or secondary to wear and tear within the fibular groove. Since then, Sammarco" and DiRaimondo2,15 and Speer and Bassett" reported this lesion in a young athletic population who presented with lateral ankle pain and symptoms of ankle instability. Their report supports a more traumatic (repetitive ankle sprain) etiology for the lesion based upon a history of trauma and young age. In cadaveric dissections performed by the authors in mostly elderly specimens, the lesion was found to be present in a significant number of ankles without evidence of trauma or ligamentous injury.17,18,23 Furthermore, histologic evaluation of these splits has shown evidence of chronic wear and tear effects on the collagen with the presence of sufficient vascularity to mount a reparative healing response.":" In an attempt to elucidate the pathogenesis of this lesion, the authors studied the dynamics of simulated peroneal contraction and tendon movement at the fibular groove in cadaveric specimens with peroneus brevis tendon splits. These studies suggest a mechanical etiology of peroneus brevis tendon splits that explains the initiation, propagation, and permanance of peroneus brevis splits in both an elderly and young population. Our understanding of the dynamic etiology of peroneus brevis tendon splits suggests that a recreation of the retaining force created by the superior peroneal retinaculum (SPR) would accentuate the patient's pain when a peroneus brevis tendon split is present (i.e., the Peroneal Tunnel Compression Test). This can be done by exerting pressure against the tightening tendons at the level of the SPR. Careful palpation of the posterior border of the fibula, at the origin of the SPR, while the patient everts the involved ankle against resistance, allows detection of snapping, popping, or partial tendon
* Orthopaedic Resident, The Hospital for Special Surgery, New York, New York 10021. To whom requests for reprints should be addressed at c/o Roger A. Mann, M.D., 237 Estudillo Ave., San Leandro, California 94578. t Private Practice, Orthopaedic and Trauma Surgeons, Somersworth, New Hampshire 03878. :j: Staff Orthopaedic Surgeon, Major, MC USA, Walter Reed Army Medical Center, Washington, DC 20307-5001. § Clinical Associate Professor of Orthopaedics, The Hospital for Special Surgery. II Director, Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824-1314.
413
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
414
SOBEL ET AL.
Foot & Ankle/Vol. 13, No. 7/September 1992
subluxation that accompanies the pain experienced by patients with symptomatic longitudinal splits of their peroneus brevis tendon. This correlated with our understanding of the pathomechanics leading to longitudinal splits of the peroneus brevis tendon, and may be a helpful aid in the clinical diagnosis of peroneus brevis splits. We have used this test successfully with operative confirmation in seven cases. We have also sought to classify the lesion based on the extent of the split. MATERIALS AND METHODS
Fig. 1. Photograph showing the position of the examiner's thumb spanning the posterior ridge of the fibula to the calcaneus and compressing the peroneal tendons and superior peroneal retinaculum as the foot is actually moved from a plantarflexed, inverted position to a dorsiflexed and everted position.
Since the prevalence of peroneus brevis splits is relatively common in cadaveric specimens, we have been able to dynamically demonstrate the lesion by (1) removing the skin and subcutaneous tissue from the lateral ankle, (2) exposing the peroneus longus and peroneus brevis tendons from the upper third of the tibia down to the level of the fifth metatarsal, (3) mimicking contraction of the peroneus longus muscle by manually tensing the peroneus longus tendon while everting the hindfoot and midfoot, (4) performing item 3 before and after releasing the superior peroneal retinaculum, and, finally, (5) inspecting the peroneus brevis tendon in the fibular groove. Photographs, illustrations, and a videotape were taken of the lateral ankle in three positions: (1) at rest (no eversion of the foot and no pull on the peroneus longus tendon), (2) moderate pull on the peroneus longus, moderate manual eversion of the hindfoot and midfoot, and (3) maximal pull on the peroneus longus, maximal manual eversion of the hindfoot and midfoot. The above sequence was performed on 15 specimens of which five had peroneus brevis splits. The specimens were fresh frozen and included both sexes. All were from adults. Peroneal Tunnel Compression Test
Fig. 2. Photograph showing that, alternatively, the examiner may place the index, middle, and long fingertips directed posteriorly over the posterior edge of the fibula while resting ankle eversion with the opposite hand.
The patient is asked to sit on the end of an examining table with the knee of the involved extremity bent to 90 0 and the foot and ankle relaxed in a plantarflexed position. Next, the examiner places his or her thumb over the superior peroneal retinaculum from the posterior ridge of the fibula to the calcaneus and presses gently downward on the peroneal tendons while at rest. Then the patient is asked to. forcefully dorsiflex and evert the foot and ankle while the examiner holds his or her thumb firmly over the superior peroneal retinaculum (Fig. 1). A positive test is marked by a recreation of the patient's pain. Crepitus or squeaking of the involved tendons (wet leather sign) may be palpable." Alternatively, the examiner may place the index, middle, and long fingertips directed posteriorly over the posterior edge of the fibula, while resisting ankle eversion with the opposite hand (Fig. 2). Additional findings may
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & AnkJejVoJ. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
415
Fig. 3. A. This photograph demonstrates the relationship between the peroneus brevis, peroneus longus, and posterior edge of the fibula, with no pull on the peroneus longus and the foot in neutral alignment. B, This photograph demonstrates the same relationship as Figure 1A from a posterior view. C, This illustration further characterizes the photograph in Figure 1A. D, This illustration shows a cross-section of the ankle (illustrated in Fig. 1B) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
416
SOBEL ET AL.
Foot & AnklejVol. 13, No. 7/September 1992
Fig. 4. A, This photograph demonstrates the relationship between the peroneus longus and peroneus brevis, with moderate pUll on the peroneus longus and moderate eversion of the foot. B, This photograph demonstrates the same relationship as Figure 2A from a posterior view. C, This illustration further characterizes the photograph in Figure 2A. 0, This illustration shows a cross-section of the ankle (illustrated in Fig. 28) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
417
Fig. 5. A, This photograph shows the relationship between the peroneus longus and peroneus brevis, with maximal pull on the peroneus longus and maximal eversion of the foot. B, This photograph demonstrates the same relationship as shown in Fig. 3A from a posterior view. C, This illustration further characterizes the photograph in Figure 3A. D, This illustration shows a cross-section of the ankle (illustrated in Fig. 38) at the level of the fibular groove.
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
418
SOBEL ET AL.
Foot & AnklefVol. 13, No. 7/September 1992
Fig. 7. This photograph demonstrates a grade I peroneus brevis split: splayed out.
Fig. 6. A, This photograph reveals a peroneus brevis split with the posterior edge of the fibula protruding through the split. B, This photograph demonstrates the same relationship seen in Figure 4A from a posterior view.
TABLE 1 Grading Scale for Peroneus Brevis Splits Grade I Grade II Grade III Grade IV
Splayed out (Fig. 7) Partial thickness split 2 cm
be a jumping sensation, triggering or clicking of the peroneal tendons within the groove, or a sensation of the anterior half of the peroneus brevis tendon attempting to subluxate over the sharp posterior ridge of the fibula.
RESULTS
In the specimens that had peroneus brevis splits, the pull of the peroneus longus with eversion of the foot always demonstrated compression of the peroneus brevis by the peroneus longus at the fibular groove. The flattened peroneus brevis tendon splayed out, with the anterior portion of the tendon slipping forward, out of the groove, and over the sharp posterior edge of the fibula. Wedged against the knife-like posterior edge of the fibula, all dissected peroneus brevis splits were found to occur at this point. The sequence is accentuated when the superior peroneal retinaculum is released because this removes the only structure that holds the peroneus brevis in the groove as the peroneus longus tightens down against it (Figs. 3-6). The lesion created in the peroneus brevis is variable in both length and thickness (partial versus full); accordingly, the authors propose a grading scale to quantify the extent of split lesions ranging from simple splaying out of the
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
PERONEUS BREVIS TENDON SPLITS
419
Fig. 8. This photograph demonstrates a grade II peroneus brevis split: partial thickness 2 em.
tions of elderly specimens as well as in patients with subluxating peroneal tendons.':" Anatomic factors can be implicated in contributing to incompetence of the superior peroneal retinaculum. Peroneus brevis splits with subluxating peroneal tendons in the presence of an anomalous low-lying peroneus brevis muscle belly causing a crowding phenomenon within the fibular groove have been reported.":" Hammerschlag and Goldner?suggest that an encroachment phenomenon develops within the fibular groove by an anomalous extra peroneus brevis that leads to subluxation of the peroneal tendons. Other congenital abnormalities of the peroneal tendons have been well described, all potentially affecting the competence of the restraints at the fibular groove. 14,22.25 Peroneal tendon subluxation is associated with the creation of peroneus brevis splits. Any incompetence of the peroneal restraints that allows the flattening and migration of the anterior portion of the peroneus brevis out of the fibular groove can result in a split. The authors
have also looked at the questionable role of hypovascularity as an etiology of peroneus brevis splits, and these studies have shown that a sufficient supply of blood to the peroneus brevis tendon does exist at the split.21 This is in agreement with the ample vascularity seen in histologic specimens." The compression of the peroneus brevis tendon by the wedge-like peroneus longus prevents repair mechanically and dynamically. This paper describes a new clinical test to aid in the diagnosis of peroneus brevis splits. Because longitudinal splits in the peroneus brevis do not necessary affect the integrity or strength of the tendon, it is difficult to ascertain whether or not an injury to the peroneus brevis tendon is present. The mechanism of peroneus brevis splits is likely secondary to a dynamic insult to the tendon as it subluxates out over the posterior ridge of the fibula1?,19,22-24,26 and secondary to peroneus longus tendon compression and SPR laxity. The SPR may become partially attenuated and/or detached from the posterior border of the fibula, either from primary injury to the retinaculum or due to repetitive loading of the peroneus brevis against it. This creates a more capacious peroneal tunnel, but allows the peroneus brevis tendon to subluxate laterally over the sharp posterior ridge of the fibula. This ridge may be blunt or sharp and is more variable from individual to individual. It appears from our cadaveric work that the presence of a sharp posterior ridge, as opposed to a rounded or flat posterior ridge, enhances the ability of the fibula to split the peroneus brevis tendon. Factors that contribute to "overcrowding" within the peroneal tendon sheath and fibular groove include tenosynovttis,? peroneus longus or brevis tendon hypertrophy secondary to attrition, anomalously distal muscle insertion into the peroneus brevis tendon.v" and the presence of a peroneus quartus tendon." During resisted eversion, the peroneus longus tendon compresses against the peroneus brevis tendon anteriorly. If the SPR fails to contain the peroneus brevis tendon, a portion of it subluxates laterally, often accompanied by a painful click. The subluxated peroneus brevis tendon may become split as it rides over the posterolateral edge of the fibula. Palpation over the peroneal tunnel thus permits detection of partial tendon subluxation as well as compresses the peroneal tunnel. Compression of the tunnel produces pain caused by tenosynovitis, which may accompany longitudinal splits of the peroneus brevis tendon. It makes sense that the recreation of a firm superior peroneal retinaculum that prohibits this subluxation will exacerbate pain. Clinical findings can be supported by perpendicular axial cuts at the level of the posterior ridge of the fibula on magnetic resonance imaging or CT evaluation, which has been shown to identify this
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
Foot & Ankle/Vol. 13, No. 7/September 1992
lesion quite well." In cases refractory to conservative treatment, exploration of the peroneal sheath is recommended. If a peroneus brevis split is found upon exploration, debridement of the tendon edges and repair of the peroneus brevis split, in addition to tubing of the tendon and reefing of the superior peroneal retinaculum, seem warranted. 19 ,20 In addition, when present, the sharp posterior ridge of the fibula can be removed as well as. This both removes a possible insult to the tendon and creates an excellent bony bed for the SPR advancement and repair." Furthermore, any additional overcrowding within the peroneal tunnel by the presence of an anomalous low-lying peroneus brevis muscle or the presence of a peroneus quartus tendon should be removed, thus decompressing the peroneal tunnel. In conclusion, the results of this study demonstrate that peroneus brevis splits are common dynamic lesions that are caused by a combination of (1) superior peroneal retinacular laxity, either traumatic or degenerative; (2) a shallow fibular groove or anomalous muscles or tendons leading to incompetence of the superior peroneal retinaculum; (3) peroneus longus compression; and (4) a sharp posterior edge of the fibula. This mechanical etiology explains why the lesion can be seen in young athletic patients with subluxating peroneal tendons and/or lateral ankle instability, as well as in the elderly with no identifiable risk factors.":" A grading scale (based on cadaveric findings) is described to further clarify the extent of the peroneus brevis split, which may have clinical implications in future reports on surgical treatment for this entity. Because this is a cadaveric study, this classification cannot give any prognosis. It serves merely as a method for surgeons to group lesions so that, in the future, classification, treatment, and outcome may be uniformly reported.
REFERENCES 1. Arrowsmith, S.R., Fleming, L.L., and Allman, F.L.: Traumatic dislocations of the peroneus tendons. J. Sports Med., 11:142146,1983. 2. DiRaimondo, C.: Overuse conditions of the foot and ankle. In Foot and Ankle Manual. A.O.F.A.S., Sammarco, G.J. (ed.), Philadelphia, Lea & Febiger, 1991, Ch. 21, p. 266. 3. Eckert, W.R., and David, E.A., Jr.: Acute rupture of the peroneal retinaculum. J Bone Joint Surg., 58A:670-673, 1976. 4. Edwards ME.: The relations of the peroneal tendons to the fibula, calcaneus, and cuboideum. Am. J. Anat., 42:213-253, 1928. 5. Evans, J.D.: Subcutaneous tear of the tendon of peroneus longus. J. Bone Joint Surg., 48B:507-509, 1966.
PERONEUS BREVIS TENDON SPLITS
421
6. Geppert, M.J., Sobel, M., and Davis, W.H.: Encroachment at the fibular groove secondary to anomalous low-lying peroneus brevis muscle belly: an anatomic study and report of two cases. Presented at the A.O.FAS. Annual Summer Meeting, Napa California, July 1992. Clin. Anat. (in press). 6a. Geppert, M.J., Sobel, M., and Bohne, W.H.O.: The mechanism of superior peroneal retinacular laxity secondary to lateral ankle instability: an anatomic study. Presented at the A.O.FAS. Annual Summer Meeting, Napa, California, July 1992. 7. Hammerschlag, W.A., and Goldner, J.L.: Chronia peroneal tendon subluxation produced by an anomalous peroneus brevis: a case report and review of the literature. Foot Ankle, 10:45-47, 1989. 8. Jones, D.C.: Bucket handle tears of the peroneus brevis tendon. Presented at the American Orthopaedic Foot and Ankle Society, Summer Meeting, Sante Fe, NM 1987. 9. Larsen, E.: Longitudinal rupture of the peroneus brevis tendon. J. Bone Joint Surq.; 69B:340-341, 1987. 10. Martens, M.A., Noyez, J.F., and Mulier, J.C.: Recurrent dislocation of the peroneal tendons. Result of rerouting the tendons under calcaneofibular ligament. Am. J. Sports Med., 14:148150,1986. 11. Meyers, A.W.: Further evidence of attrition in the human body. Am. J. Anat., 34:241-267,1924. 12. Munk, R.L., and Davis, P.H.: Longitudinal ruptures of the peroneus brevis tendon. J. Trauma, 16:803-806,1976. 13. Purnell, M.L., Drummond, D.S., Engbar, W.O., and Breed, A.L.: Congenital dislocation of the peroneal tendons in the calcaneovalgus foot. J. Bone Joint Surg., 65B:316, 1983. 14. Sammarco, G.J., and Brainard, B.J.: A symptomatic anomalous peroneus brevis in a high jumper: a case report. J. Bone Joint Surg., 73A:131-133, 1991. 15. Sammarco, G.J., and DiRaimondo, C.V.: Chronic peroneus brevis tendon lesions. Foot Ankle, 9:163-170,1989. 16. Sammarco, J.: Letter to the editor re: longitudinal attrition of the peroneus brevis tendon in the fibular groove: an anatomic study. Foot Ankle, 11:248, 1991. 17. Sobel, M., Bohne, W.H.O., DiCarlo, E., and Collins, L.: Longitudinal splitting of the peroneus brevis tendon: an anatomic and histologic study of cadaveric material. Foot Ankle, 12:165-170, 1991. 18. Sobel, M., Bohne, W.H.O., Markisz, J., and Collins, L.: Cadaver correlation of peroneal tendon changes with magnetic resonance imaging. Foot Ankle, 11:384-388, 1991. 19. Sobel, M., Geppert, M., and Warren, R.F.: Chronic ankle instability as a cause of peroneal tendon injury. Clin. Orthop. (in press). 20. Sobel, M., and Geppert, M.J.: Repair of concomitant lateral ankle ligament instability and peroneus brevis splits through a posteriorly modified Brostrom Gould. Foot Ankle, 13:224-225, 1992. 21. Sobel, M., Geppert, M.J., Bohne, W.H.O., and Hannafin, J.A.: The microvascular anatomy of the peroneal tendons. Foot Ankle (in press). 22. Sobel, M., Levy, M., and Bohne, W.H.O.: Congenital variations of the peroneus quartus muscle: an anatomic study. Foot Ankle, 11:81-89, 1990. 23. Sobel, M., Levy, M. E., and Bohne, W.H.O.: Longitudinal attrition of the peroneus brevis tendon in the fibular groove: an anatomic study. Foot Ankle, 11:124-128,1990. 24. Sobel, M., Levy, M.E., and Bohne, W.H.O.: Longitudinal attribution of the peroneus brevis tendon in the fibular groove: an
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
422
SOBEL ET AL.
Foot & AnklejVol. 13, No. 7 jSeptember 1992
anatomic study. Letter to the editor: author's response. Foot Ankle, 11:249-251, 1991. 25. Sobel, M., O'Brien, S.J., and Bohne, W.H.O.: Longitudinal attrition of the peroneus brevis tendon secondary to an encroachment phenomenon within the peroneal tendon sleeve: a report of two cases. Acta Orthop. Scand. (in press). 26. Sobel, M., Warren, R.F., and Brourman, S.: Lateral ankle insta-
bility associated with dislocation of the peroneal tendons treated by a modified Chrisman-Snook procedure: a new technique and review of the literature. Am. J. Sports Med., 18:539-543, 1990. 27. Speer, K.S., and Bassett, F.: Chronic tears of the peroneal tendons. Presented at the annual American Academy of Sports Medicine Summer Meeting, Orlando, FL, 1991. Am. J. Sports Med. (in press).
Downloaded from fai.sagepub.com at The University of Iowa Libraries on June 25, 2015
