Accessory FDL causing Tarsal Tunnel Symptoms in a 15 Year Old Girl: A Case Study Ali Rahnama DPM, Tara Stock DPM FACFAS Detroit Medical Center Discussion: Abstract: is a common pathology known to the and Case Presentation: The presence of an accessory flexor digitorum longus (FDAL) has been surgeon that often requires surgical intervention for resolution of A 15 year old female cross country runner presented to the Foot and sparsely reported in the foot and ankle literature. This makes for a particularly symptoms (4). While there are many etiologies, once diagnosed Ankle clinic with a two month history of pain with shooting into the plantar challenging diagnosis for the practitioner, especially without more advanced appropriately, the treatment options are few in number and often gravitate aspect of the right foot with a sharp nature when running. She reported imaging modalities present. The current case presents a 15 year old track and towards surgery. While there are many possible etiologies for tarsal that the pain subsided with a short rest period. Her past medical history field runner who presented with tarsal tunnel symptoms only when running at tunnel syndrome, Cimino and colleagues reported that 34% were was noncontributory and her mother reported a full term birth with no which point she had to stop due to increased pain that would subside with a idiopathic (5). This suggests that the involvement of more advanced complications. short period of rest. Ultimately she was found to have an FDAL which was imaging modalities or techniques such as MRI may help the practitioner On physical exam the patient has a positive Tinnel sign with mild pain resected operatively at which point she was able to return to full physical reach a definitive diagnosis more quickly (6-9). on palpation over the posterior . X-ray revealed no abnormality activity at the competitive level. and it was elected to obtain an MRI (Figure 1) due to the patients young Conclusion:

Introduction: age and odd onset of symptoms (i.e. with moderate to intense physical The current case represents a 15 year old runner with TTS secondary Tarsal tunnel syndrome can have many etiologies and is a relatively activity with a resolution of symptoms with little rest). MRI revealed an to an accessory FDL muscle. The Patient had complete resolution of common pathology that presents to the Foot and Ankle Surgeon. The basic accessory FDL tendon/muscle to the right lower extremity with a low lying symptoms at almost one year follow up with no complications following premise being that the tibial nerve has little room for compensation being muscle belly into the tarsal canal. We hypothesized that the low lying surgical resection. enclosed in the flexor retinaculum and is therefore vulnerable to changes in muscle belly was the cause of the pain. The muscle likely had little effect References: the volume of the “tarsal tunnel”. Possible etiologies include tumor, on the nerve at rest but with activity if likely increased in volume with 1) M. Ahmad, K. Tsang, P.J. Mackenney, A.O. Adedapo, Tarsal tunnel tenosynovitis, varicosities, bone spur, valgus foot type as well as the increased blood flow to the muscle and that was when the patient syndrome: A literature review, Foot and Ankle Surgery, Volume 18, Issue presence of accessory muscles (1). experienced her symptoms. It was elected after discussion with the 3, September 2012, Pages 149-152 The presence of an accessory flexor digitorum longus (FDAL) has an patient and her mother that she would need surgical intervention for 2) Nathan, H. Flexor digitorum accessorius longus.Clinical orthopaedics resolution of her symptoms. incidence as high as twelve percent in the population (2). The sparsity in and related research (1975) 113: 158 reporting this anatomic variant in the Foot and Ankle literature may The patient was placed on the operating table in the supine position 3) Cheung, Y., Rosenberg, Z., Colon, E. et al. MR imaging of flexor contribute to a difficulty in pinpointing it as a pathological source for the with her right leg in the frog leg position. Careful dissection was carried digitorum accessorius longus.Skeletal Radiol (1999) 28: 130. patients tarsal tunnel syndrome (TTS) without more advanced imaging (3). down, the flexor retinaculum or lanciniate ligament was incised and the 4) Burks JBJ. The Journal of foot and ankle surgery: Tarsal tunnel The current case report is of a case of TTS in an adolescent runner accessory muscle with its tendon were identified just inferior to the flexor syndrome secondary to an accessory muscle: a case report. Williams & Wilkins; 11/2001;40:401 digitorum longus tendon and superior to the neurovascular bundle (Figure whose symptoms resolved with surgical resection of the FDAL. 5) Cimino, W. R. Tarsal tunnel syndrome: review of the literature. Foot 2). The muscle belly could be traced proximally about 2-3 cm proximal to Ankle 11:47-52,1990 the medial malleolar tip and distally about 2 cm proximal to the navicular 6) T. H. Lui, “Arthroscopy and endoscopy of the foot and ankle: indications tuberosity. While the adjoining slips of the accessory tendon were also for new techniques,” Arthroscopy, vol. 23, no. 8, pp. 889–902, 2007 excised (Figure 3), ultimately we elected to leave the small slips left 7) C. N. van Dijk, “Hindfoot endoscopy for posterior ankle pain,” Instructional Course Lectures, vol. 55, pp. 545–554, 2006 behind after our resection of the muscle belly (Figure 4). 8) W. R. Buschmann, Y. Cheung, and M. H. Jahss, “Magnetic resonance The patient tolerated this procedure well without complications. We imaging of anomalous leg muscles: accessory soleus, peroneus quartus followed her weekly for wound check for one month at which point she and the flexor digitorum longus accessorius,” Foot and Ankle, vol. 12, no. returned to full activity. She reported complete resolution of symptoms 2, pp. 109–116, 1991. and is asymptomatic at almost one year with a full return to cross country 9) Ho VWV. Journal of computer assisted tomography: Tarsal tunnel syndrome caused by strain of an anomalous muscle: an MRI-specific running. diagnosis. Lippincott Williams and Wilkins; 09/1993;17:822.