Case Report
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Dec 16, 2022; 10(35): 13022-13027
Published online Dec 16, 2022. doi: 10.12998/wjcc.v10.i35.13022
Symptomatic accessory soleus muscle: A cause for exertional compartment syndrome in a young soldier: A case report
Inha Woo, Chul Hyun Park, Hongfei Yan, Jeong Jin Park
Inha Woo, Hongfei Yan, Jeong Jin Park, Department of Orthopaedic Surgery, Yeungnam University Hospital, Daegu 42492, South Korea
Chul Hyun Park, Department of Orthopaedics, Yeungnam University Hospital, Daegu 42415, South Korea
Author contributions: Woo I, Park CH, Yan H, and Park JJ contributed to the conception the study; Woo I designed the study; Park CH performed the study; Park JJ analyzed the data; Woo I and Yan H wrote the paper; Park CH contributed to the revision process and wrote the revised manuscript; All authors have read and approved the final manuscript.
Informed consent statement: All study participants or their legal guardian provided informed written consent about personal and medical data collection prior to study enrolment.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Chul Hyun Park, MD, PhD, Chief Doctor, Professor, Surgeon, Department of Orthopaedics, Yeungnam University Hospital, No 170 Hyeonchungno, Namgu, Daegu 42415, South Korea. chpark77@naver.com
Received: August 8, 2022
Peer-review started: August 8, 2022
First decision: October 12, 2022
Revised: October 24, 2022
Accepted: November 17, 2022
Article in press: November 17, 2022
Published online: December 16, 2022
Processing time: 128 Days and 3 Hours
Abstract
BACKGROUND

Accessory soleus muscle (ASM) is a rare congenital variation that is almost asymptomatic, but several papers have recently described symptomatic ASM. The clinical features of this condition are similar to tarsal tunnel syndrome (TTS) and include pain and numbness around the medial side of the ankle. ASM commonly originates from the fibula or soleus muscle and inserts into the Achilles tendon or calcaneus. Usually, it is identified as posteromedial swelling and definitely diagnosed by magnetic resonance imaging. In most cases, treatment is observation, but surgical excision can be considered if symptoms are severe.

CASE SUMMARY

A 23-year-old male Korean soldier presented with complaints of bilateral foot and ankle pain and a swelling medial to the Achilles tendon that was more pronounced on the right side. Symptoms first occurred after playing soccer 10 mo before this presentation, worsened after physical exertion, and were relieved by rest. He had no medical history, and no one in his family had the condition. Laboratory results were non-specific. Several tests were performed to exclude common diseases such as tumors or TTS. However, MRI revealed a bulky accessory soleus muscle in both feet, though the patient complained of more severe pain on the right side during physical activity. Accordingly, surgical resection was adopted. At surgery, a large accessory soleus muscle was noted anterior to the Achilles tendon with distinctive insertion from a normal soleus muscle. At 12 mo after surgery, there was no pain, numbness, or swelling of the right foot or ankle, no evidence of recurrence, and the patient could do all sports activities.

CONCLUSION

Accessory soleus muscle should be added to the list of differential diagnosis if a patient has pain, sole numbness or swelling of the posteromedial ankle.

Keywords: Accessory soleus muscle; Posteromedial ankle pain; Exertional compartment syndrome; Tarsal tunnel syndrome; Sole numbness; Case report

Core Tip: The Accessory soleus muscle (ASM) is considered a rare congenital variation, and is usually asymptomatic. However, patients can present with sole numbness, posteromedial ankle pain, and, in rare cases, exertional compartment syndrome. In the majority of cases, diagnosis can be confirmed by magnetic resonance imaging. Observation is commonly recommended but surgical resection can be considered if symptoms are severe. ASM should be added to the list of differential diagnosis if a patient has pain, sole numbness, or swelling of the posteromedial ankle.