International Medical Journal Vol. 28, No. 2, pp. 240 - 242 , April 2021

ANATOMY

The Prevalence of the Accessory Peroneal Muscle; Peroneus Quartus and Its Clinical Implications

Chirapat Inchai1), Theerachai Apivatthakakul2), Apichat Sinthubua1), Pasuk Mahakkanukrauh1,3)

ABSTRACTObjective: The peroneus quartus (PQ) muscle is the most frequently reported in the literature review as an accessory muscle

of the lateral compartment of the leg. The purpose of this study was to evaluate the morphological study of the accessory muscle of the lateral compartment of leg.

Design: Cadaveric StudyMaterials and Methods: Sixty fresh cadaveric lower limbs were dissected to study the PQ muscle. A quantitative descriptive

study will be conducted for study of morphology of the PQ muscle, the origin and the insertion of the PQ muscles was evaluated. The photographs were made for data collection.

Results: The PQ muscle was found in 4 of 60 specimens (6.67%). All of PQ muscle was found in unilaterally. The insertion of all of the PQ muscles was found at the lateral surface of the calcaneus especially to the retrotrochlear eminence.

Discussion: The present of the accessory peroneal muscle resulting in peroneal retinaculum or tendon sheath stenosis as a result of peroneal tendinitis. Peroneal tendinitis commonly found as a result of repetitive activity, direct trauma, chronic lateral ankle instability, the fractures of calcaneus or ankle, or severe ankle sprains. The presence of accessory peroneal muscle espe-cially the PQ muscle associated with the chronic pain at the ankle

Conclusion: The results of the present study provide the anatomical knowledge of the accessory muscle that can be found at the lower extremity which may help the surgeon to keep in mind and choose the appropriate treatment for their patients and reducing the rate of complications in surgery.

KEY WORDSperoneus longus, peroneus brevis, peroneus quartus, peroneal tendon, ankle

Received on June 14, 2020 and accepted on September 9, 20201) Department of Anatomy, Faculty of Medicine, Chiang Mai University 50200, Thailand2) Department of Orthopedics, Faculty of Medicine, Chiang Mai University 50200, Thailand3) Excellence in Osteology Research and Training Center (ORTC), Chiang Mai University 50200, ThailandCorrespondence to: Pasuk Mahakkanukrauh (e-mail: pasuk034@gmail.com)

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INTRODUCTION

The lateral compartment of lower leg composed of two muscles; peroneus or fibularis longus and brevis muscle. The peroneus quartus (PQ) muscle is the most frequently reported in the literature review as an accessory muscle of the lateral compartment of the leg (Athavale et al., 2012). The prevalence of PQ muscle varies from 12 to 22 % (Sobel et al., 1990). The description of the muscle also widely in different name according to its origins and insertions, including peroneocalcane-us externum, peroneocuboideus, long peroneal tendon, and peroneoper-oneolongus (Cheung et al., 1997). The PQ muscle was originated from the lower one third of the leg mostly originates from the peroneus brevis muscle or peroneus longus muscle, the insertion of PQ muscle was high variation such as retrotrochlear eminence of the calcaneus, the peroneal trochlear of the calcaneus, cuboid and fifth metartarsal bone. The func-tion of the PQ muscle plays the role of lateral stabilization by support the lateral edge of the foot and also foot eversion. Otto and colleagues in 1816 who was the first reported the description of the peroneus quar-tus muscle. Previous studies have been reported the prevalence of the

PQ by using various methods such as the MRI, ultrasound and cadaveric dissection. Sobel and colleagues (Sobel et al., 1990) performed the ana-tomical study on 124 lower legs of the cadavers and reported the PQ was present in 21.7% of cadavers.

On the recent studies of the accessory muscle of the lower extremi-ty, there are numerous studies reported the gross anatomy of the perone-us quartus muscle, peroneus digit quinti muscle and the peroneus acces-sories muscle to evaluate the morphology, origins, insertions, and the location of PQ muscle. White (White, Johnson, Griswold, 1974) report-ed the chronic ankle pain associated with the present of the peroneus accessorious muscle, the lower part of the muscle belly of the peroneus accessorious muscle impinged the peroneal retinaculum at the ankle joint that can cause the ischemia, irritation and pain at the ankle joint. The purpose of present study investigated the prevalence of the PQ muscle and morphological variation related to the clinical implications in the Northern Thai population.

C 2021 Japan University of Health Sciences & Japan International Cultural Exchange Foundation

Inchai C. et al. 241

MATERIALS AND METHODS

A total of 60 lower limbs fresh frozen cadavers; 8 females and 22 males was conducted in the present study. The specimens obtained from Department of Anatomy, Faculty of Medicine, Chiang Mai University. A mean age at death between 20 to 80 years. No history of lower extremi-ty injury, pathology and ankle deformity was reported. Ethical approval for the present study was obtained from the ethics committee from the Faculty of Medicine, Chiang Mai University. The morphological study of the peroneus quartus was study by dissection. A quantitative descrip-tive study will be conducted for study of morphology of the peroneus, the origin and the insertion of the peroneus quartus muscles was evalu-ated. The photographs were made for data collection. The record was made of the morphology of the peroneus quartus muscle and tendon such as the origin, insertion and variations.

RESULTS

The peroneus quartus muscle was found in 4 of 60 specimens (6.67%). All of PQ muscle was found in unilaterally. The PQ muscle was originated from the muscle at the posterolateral part of distal fibula with the muscle belly and slender tendon (Figure 1). The PQ muscle and tendon passed posterior to the lateral malleolus and insert to the lateral surface of the calcaneus (Figure 2). This muscle was innervated by the superficial branch of the common peroneal nerve near its origin. No other muscular variations were noted in the limbs of specimens.

DISSCUSSIONS

In the current publication, there are few anatomical studies investi-gated the origins of the peroneus quartus muscle such as the peroneus longus and peroneus brevis muscle, the tendon of the peroneus brevis and the lower part of the fibula while the insertion variously onto the

Figure 1: The peroneus quartus (PQ) muscle in the lateral compartment of the leg, 1a; at the lateral view and 1b; at the posterior view. The slender tendon of PQ muscle passed posterior to the lateral malleolus to insert the lateral surface of the calcaneus.

Figure 2: The insertion of the PQ tendon to the lateral surface of the calcaneus.

Prevalence of Peroneus Quartus Muscle242

calcaneus at the retrotrochlear eminence, the peroneal tubercle, the ten-dons of the peroneus longus and brevis, the retinaculum and the talus (Cheung et al., 1997; Clarkson et al., 2013; Donley & Leyes, 2001; Sobel et al., 1990; Tubbs et al., 2008; Zammit & Singh, 2003). Duran-Stanton has been reported the prevalence of the PQ muscle ranged from 10-26% which located superficial to the flexor retinaculum. The PQ muscle was originated from the lateral aspect of the distal fibula and continuous with a thin tendon, 79% was insert in the calcaneus (Duran-Stanton & Bui-Mansfield, 2010).

In the present study found that all of the PQ arising from the muscle belly from the peroneus brevis muscle and its tendon located at the distal fibula to insert at the lateral surface of the calcaneus. Cheung in 1997 determined the prevalence of the PQ muscle and demonstrated the mor-phology of the accessory muscle by using the magnetic resonance (Cheung et al., 1997) images. The result shown the prevalence of the PQ muscle was 10% (14 of 136 specimens), the PQ muscle was common found in male patients (Cheung et al., 1997). Athavale in 2012 observed the morphology and the prevalence of the peroneus quartus muscle in 92 lower limbs of formalin fixed cadavers. The result shown the PQ was reported in 21% of all specimens originate from distal part of the fibula especially in the lateral site and peroneus brevis muscle or the intermus-cular septum (Athavale et al., 2012). Hur and colleagues in 2015 per-formed the cadaveric study of 80 formalin fixed specimens of Korean cadavers and classified the morphological patterns of the PQ muscle into 6 types. The result found the presenting of the PQ in 16.3% and divided the pattern of the insertion into subtypes (Hur, Won, Chung, 2015).

The present cadaveric study shown the prevalence of the peroneus quartus muscle of 6.67% (4 of 60 specimens). This result was contrasts to the study of Sobel and colleaque in 1990 (Sobel et al., 1990) and Athavale in 2012 (Athavale et al., 2012) reported the incidence of PQ muscle was found with 21.7%. Furthermore, Yammine (Yammine, 2015) reported the high incident of PQ muscle in Indian populations compared to other population and the incident of peroneus digit quinti muscle was high prevalent in Americans and Europeans populations compared to Japanese and Korean populations. The previous studies reported a greater incidence of the PQ muscle and its variants in males (Yammine, 2015; Zammit & Singh, 2003). Similarly, the present study shown the present of the PQ muscle in males with the 75%.

The anatomical structures include the present of the accessory pero-neal muscle such as PQ muscle, the os peroneum enlargement or hyper-trophy of the peroneal tubercle resulting in peroneal retinaculum or ten-don sheath stenosis as a result of peroneal tendinitis. Peroneal tendinitis commonly found as a result of repetitive activity, direct trauma, chronic lateral ankle instability, the fractures of calcaneus or ankle, or severe ankle sprains. The presence of accessory peroneal muscle especially the PQ muscle associated with the chronic pain at the ankle and the lateral hind foot area by the mechanical impingement of the surrounding struc-tures (Sobel, Bohne, Markisz, 1991). Lolito (Lotito et al., 2011) was investigated the PQ muscle played a role in functional ankle instability. Wenning (Wenning, Heitner, Ulrich, Paul, Rist, 2019) reported the chronic exertional compartment syndrome (CECS) associated the pre-senting of the peroneus quartus muscle. Another reported by Oznur (Öznur, Arik, Alanay, 2002) reported alleviation of lateral ankle pain after dissection of a peroneus quartus muscle.

The primary management of the chronic ankle pain is conservative treatment for reduce pain and restoring functional stabil i ty. Conservative treatment comprises of the anti-inflammatory drugs such as local corticosteroid injection, ultrasound-guide injection, immobiliza-tion from the activities and physical therapy. The operative treatment is considered to solve these problems when conservative treatment is not success. In addition, surgeons should consider the presence of such anomalous muscles because of their potential use in surgical reconstruc-tion. The tendon of such muscles could be used for various reconstruc-tive procedures involving the lateral part of the ankle.

CONCLUSIONS

The present study evaluated the specific detailed of the peroneus quartus muscle anatomic information some of which are the description of the term of the origin and the insertion. The precise and specific ana-tomical attachment of the PQ which may help the surgeon to identified and optimize the surgical procedure. The present study provides the more detailed of basic anatomical knowledge of the peroneus quartus muscle may help the surgeon when performing the surgical procedure for determining the appropriate technique and less complication to patients.

ACKNOWLEDGEMENT

This study was supported by research funding from the Faculty of Medicine, grant no. 153-2561 and partially supported from Chiang Mai University.

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