Foot and Ankle Surgery 18 (2012) 293–295
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Variations in the insertion of peroneus longus tendon—A cadaver study S. Shyamsundar *, A. Wazir, P.E. Allen University Hospitals of Leicester NHS Trust, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, United Kingdom
A R T I C L E I N F O
A B S T R A C T
Article history: Received 11 December 2011 Received in revised form 11 May 2012 Accepted 18 May 2012
Background: The insertion of peroneus longus is traditionally described to the plantar surface of the 1st cuneiform and 1st metatarsal. It is thought to be the main contributor to the plantarﬂexed ﬁrst ray seen in cavus feet. Methods: We studied the insertion of peroneus longus in 26 feet from 14 adult cadavers. The insertional points, presence of sesamoid bone and variations in insertion were noted. Results: The main insertion was to the base of the 1st metatarsal and the medial cuneiform in the majority of feet but variations were observed. A sesamoid bone was present within the tendon under the cuboid in 16 feet, 12 of which had additional lateral insertion bands. Conclusions: Variations in the insertion of peroneus longus were found and we have described two new lateral bands. ß 2012 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Peroneus longus Cavus feet Dissection Cadaver
1. Introduction Peroneus longus is a superﬁcial muscle in the lateral compartment of the leg. The described insertion of this tendon is to the plantar surface of 1st cuneiform and proximal 1st metatarsal . The peroneus longus tendon everts and is reported to aid in plantar ﬂexion of the foot at the ankle and to be responsible for pulling the base of the ﬁrst metatarsal inferiorly, thereby counteracting the superior pull of the anterior tibial tendon . It also acts as a stabilizer of both the longitudinal and transverse arches. These multiple functions are due to the tendon traversing several joints. Both the peroneii are strongly implicated in maintaining the concavity of the foot during toe-off and tiptoeing . Most anatomy texts and articles recognize the major insertions of the tendon into the lateral tubercle on the base of the ﬁrst metatarsal and the medial cuneiform, but the frequency of the variations of insertions of the peroneus longus tendon has not been reported [3–6]. Problems reported with the peroneus longus tendon include traumatic injury, inﬂammation of tendon or its sheath, subluxation, tears (acute injuries or chronic ruptures), and avulsion fractures. Symptoms can include pain, swelling, and ankle instability. Tears of the peroneal tendons are not uncommon, and high tensile forces can cause acute avulsion fracture through the os peroneum or a longitudinal tear with fragmentation of the
* Corresponding author. Tel.: +44 07939495576. E-mail address: [email protected]
bone . The peroneus longus tendon also has a greater role than any other tendon or ligament in resisting varus force on the ﬁrst metatarsal. Any partial or complete loss of stabilization of the ﬁrst metatarsal bone by the peroneus longus tendon leads to metatarsus primus varus . Peroneus longus is also postulated to play a major role in the deformities occurring in Charcot Marie Tooth (HSMN Types 1 and 2) disease. In fact the insertion point of peroneus longus has been postulated as the cause for major deformity in the cavo varus feet . If the tibialis anterior and peroneus brevis are weak (which is common in Charcot Marie Tooth disease), peroneus longus is thought to cause plantar ﬂexion of the ﬁrst ray, which subsequently leads to a cavus foot deformity. We felt that gaining a better understanding of the anatomical variations of the peroneus longus tendon would help us understand the cause of deformity better. While the description of insertion points for the peroneus longus tendon exists in numerous texts and articles [3–5,9], none are consistent in describing the incidences of variations of the insertional slips. Recently one of the articles described incidences of different insertion but did not look at distinguishing the types of bands based on the size and signiﬁcance . This study looked into the insertions of the peroneus longus tendon. 2. Materials and methods Dissection was performed in 26 (12 paired and 2 from disarticulated limbs) feet obtained from the Department of Anatomy in the University of Leicester.
1268-7731/$ – see front matter ß 2012 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fas.2012.05.003
S. Shyamsundar et al. / Foot and Ankle Surgery 18 (2012) 293–295 Table 1 Incidence of various bony insertions of peroneus longus. Insertional points for peroneus longus
Number (total n = 26)
Base of 1st metatarsal Medial cuneiform Base of 4/5 metatarsal Base of 2nd metatarsal Calcaneum Base of 3rd metatarsal
26 22 12 8 8 2
The cadavers used for the study were all of Caucasian origin with a age range of 71–83 (mean of 77). There were no signs of trauma to the lower limbs and no surgical scars were noted. All cadavers were embalmed by arterial embalming at the University of Leicester. This involves pumping/gravity feed of embalming ﬂuid in to the right carotid artery and is done to a closed circulatory system. The embalming ﬂuid that we use is a mixture of IMS (denatured alcohol) 99% 756 ml, phenol 80% 125 ml, formaldehyde 40% 40 ml, glycerol 44 ml, and water 35 ml (Embalming Fluid No. 4 Vickers Laboratory Ltd.). The skin, fascia, long plantar ligament, and superﬁcial muscles of the feet were removed. The peroneus longus tendon was identiﬁed behind the lateral malleolus and carefully followed up to its insertion in the foot. All the insertion slips of the tendon were located and documented. The presence of os peroneum was identiﬁed and also recorded. The insertional points were noted for the site of attachment and the number of attachments for each tendon. All data were collected in a table prospectively as the dissection was being done with photographs taken both of the course and the insertional points.
The peroneous longus tendon was easily identiﬁed and consistent in its presence behind the lateral malleolus in all 26 feet, where it was in close relationship with the peroneus brevis tendon. In all the feet the tendon (of peroneous longus) consistently went through the 4th layer of foot, i.e., the deep layer consisting of interossei muscles and the tendons of peroneus longus and tibialis posterior . The tendon of peroneus longus was covered by a synovial sheath throughout its course and was found to cross lateral to medial under the cuboid in some cases with a sesamoid (Fig. 1). All 26 specimens had an attachment to the base of the ﬁrst metatarsal by a strong band (Fig. 2). A slip to the medial cuneiform was observed in 22 specimens (85%). It was a thin slip of about 0.5 cm in most specimens , approximately 1–1.5 cm proximal to the ﬁrst metatarsocuneiform joint. Insertional slips were also observed to the lesser metatarsals (Table 1). After the peroneus longus tendon entered the cuboid tunnel a sesamoid (bony/ﬁbrocartilaneous) was present within the tendon of 16 feet. The sesamoid was lying either directly below  or just lateral to the cuboid . Additional strong lateral bands were also present in those feet where the sesamoids were bony. Bands were seen in 12 feet all of which had a very prominent strong distal band and 7 of which additionally had a proximal band (Fig. 3). The distal bands had consistent attachments to the bases of 4/5 metatarsal and the proximal band to oscalcis. All the tendons were covered by a synovial sheath throughout their courses in the feet. Among the 26 feet, 13 had insertions at four sites, three specimens at three sites, eight specimens at two sites and three specimens at ﬁve or more attachments. The strong lateral bands were quite an independent structure and there was no signiﬁcant soft tissue structures that were either noted to have any origin or
Fig. 2. Peroneus longus tendon (A) of left foot crossing the foot and inserting medially to base of 1st metatarsal (B) and medial cuneiform (C).
Fig. 3. Peroneous longus tendon (A) of right foot splitting into distal band (B) and proximal band (C).
Fig. 1. Peroneus longus tendon of the right foot going lateral to medial. A points to the sesamoid bone (os peroneum).
S. Shyamsundar et al. / Foot and Ankle Surgery 18 (2012) 293–295
Fig. 4. Variation between feet of the same cadaveric specimen. Foot on the left (A) showing no sesamoid bone and only medial insertion and the foot on the right (B) showing a sesamoid bone and lateral bands.
insertion to these bands (Fig. 3). No attritional tears in the tendon were seen in any of the specimens. Comparing the 12 paired feet dissimilarities in insertion were noted in 8 of these feet (Fig. 4) with presence of lateral bands noted in one of the feet and not in the other in 6 of them. 4. Discussion In our study we found variations in the insertion of peroneus longus not only among the different cadavers but also within the paired feet. Varying attachments of the peroneus longus tendon have been described by other authors. Sarraﬁan  observed an extension of peroneus longus tendon to the plantar aspect of the ﬁrst cuneiform, the base of the second metatarsal, and the ﬁrst dorsal interosseous. He also described the anterior frenular ligament as a ﬁbrous expansion that connects the peroneus longus tendon at the level of the cuboidal sesamoid to the base of the ﬁfth metatarsal and the origin of the short ﬂexor of the ﬁfth toe. Incidence of the anterior and posterior frenular ligaments has been reported by other authors to be 63–80% and 10–13%, respectively [9,11,12]. The frenular ligaments have been described as thin slips and seem to be different than the large strong lateral bands noted in our study. To our knowledge this is the ﬁrst time such signiﬁcant lateral band attachments have been reported. Occasional slips to the base of the second, third, fourth, and ﬁfth metatarsals and to the adductor hallucis have been described in Gray’s anatomy . Lohrmann et al.  reported that the peroneus longus tendon may also receive a slip from the posterior tibial tendon.
Picou  described at great length the insertions of the peroneus longus tendon and stated that the normal insertions are the base of the ﬁrst metatarsal, the plantar aspect of the ﬁrst cuneiform, and behind the head on the superolateral border of the ﬁrst metatarsal. He described their incidences as follows: cuneiform and ﬁrst metatarsal base, 95%; cuneiform and ﬁrst metatarsal head, 89%; and ﬁrst metatarsal base, 5.5%. He also described the slip to the ﬁrst cuneiform as arising from the dorsal surface of the peroneus longus tendon at the level of the sesamoid in the cuboid tunnel to terminate on the anterior plantar aspect of the ﬁrst cuneiform. Several authors have reported that peroneus brevis is stronger than peroneus longus in the ability to evert and abduct the foot [14,15]. The peroneus brevis tendon is commonly used in reconstruction of the ankle ligaments and the Achilles tendon [7,16,17,2]. When used as a donor for tendon transfer and ligament or tendon reconstruction, the brevis tendon is used either in part or full because function is thought not to be compromised by its sacriﬁce . In these instances, a thorough knowledge of the insertion of the only remaining evertor and abductor of the foot, the peroneus longus tendon, becomes even more relevant. References  Bohne WH, Lee KT, Peterson MG. Action of the peroneus longus tendon on the ﬁrst metatarsal against metatarsus primus varus force. Foot and Ankle International 1997;18:510–2.  Sammarco GJ, DiRaimondo CV. Surgical treatment of lateral ankle instability syndrome. American Journal of Sports Medicine 1988;16:501–11.  Gray H. In: Williams P, Salmons S, editors. Gray’s Anatomy. 38th ed., New York: Churchill Livingstone; 1995. p. 893–4.  Hollinshead WH. In: Rosse C, Gaddum-Rosse P, editors. Textbook of Anatomy. 5th ed., Philadelphia: Lippincott-Raven Publishers; 1997. pp. 378, 400–401.  Snell RS. Clinical Anatomy for Medical Students, 4th ed., Boston: Little, Brown and Company; 1992. pp. 662–665.  Last RJ. Anatomy. Regional and Applied, 6th ed., New York: Churchill Livingstone; 1978. pp. 170, 179–180.  Elmslie RC. Recurrent subluxation of the ankle joint. Annals of Surgery 1935;100:364–7.  Brewerton DA, Sandifer PH, Sweetnam DR. ‘‘Idiopathic’’ pes cavus – an investigation into its aetiology. British Medical Journal 1963;2:659.  Sarraﬁan SK. Anatomy of the Foot and Ankle. Philadelphia: JB Lippincott; 1983. pp. 208–213.  Faciszewski T, Burks RT, Manaster BJ. Subtle injuries of the Lisfranc joint. Journal of Bone and Joint Surgery 1990;72-A:1519–22.  Picou R. Insertions inferieures du muscle long peronier lateral: Anomalie de ce muscle. Bulletin de la Societe des Anatomie 1894;8:160–2.  Patil V, Frisch NC, Ebraheim NA. Anatomical variations in the insertion of the peroneus (ﬁbularis) longus tendon. Foot and Ankle International 2007;28(November (11)):1179–82.  Lohrmann S, Floel H, Christ B. Insertion of the musculus tibialis posterior into musculus peroneus (ﬁbularis) longus. Annals of Anatomy 1997;179:161–3.  Otis JC, Deland JT, Lee S, Gordon J. Peroneus brevis is a more effective evertor than peroneus longus. Foot and Ankle International 2004;25:242–6.  Sammarco GJ. Peroneal tendon injuries. Orthopedic Clinics of North America 1994;25:135–45.  McClelland D, Maffulli N. Neglected rupture of the Achilles tendon: reconstruction with peroneus brevis tendon transfer. Surgeon 2004;2:209–13.  Pintore E, Barra V, Pintore R, Maffulli N. Peroneus brevis tendon transfer in neglected tears of the Achilles tendon. Journal of Trauma 2001;50:71–8.