Anatomical Variants of the lower limb Shank Pain

Anatomical Variants of the lower limb & Shank Pain Dr Eloise Matthews MP Sports Physicians Registrar

Anatomical Variants & Shank Pain • • Accessory Soleus Popliteal Artery Anomalies PAES Other Accessory Muscles

Accessory Soleus ● Rare anatomical variant – 1 -5% ○ bilateral in 10% ● Soft tissue mass bulging medially btw distal tibia and Achilles tendon ● Asymptomatic in 25% ● Supplied by post tibial nerve ● Contained in own fascial sleeve with own blood supply ● Insertion variable: achilles / medial calcaneus / superior calcaneus. ● Associations: CECS/ Post tibial Nerve Compression (tarsal tunnel)

Investigation ● X-ray : soft tissue swelling btw deep compartment & Achilles – obliterates Kager’s triangle on lateral x-ray ● MRI confirms normal muscle & rules out tumor ● Compartment pressure testing Management ● soft tissue work, strengthening and stretching ● operative mx : ○ fasciotomy ○ excision: if no response to fasciotomy OR haemorrage/ necrosis on MRI

Popliteal Artery Anatomical Variations Normal: 1. Btw heads of gastroc 2. Posterior to popliteus 50%

Presentation: PAES ● Deep ache / cramp like pain in the calf or shank ● Pain can be worse walking: running (contraction phase) ● Paresthesias in tibial nerve distribution ● Pain disappears with exercise cessation ● Unaffected by consecutive days of exercise ● Severity related to intensity Examination: (unreliable for dx) ● 10% signs of acute or chronic lower limb ischemia ● Pop artery bruit / Pulses may be weak or absent following exercise

PAES Investigation ● Doppler U/S Dynamic and symptomatic ● MRI/MRA: ○ relationship between structures ● Angiography ● CT Angiography: ○ site of occlusion/ ddx/ anat variants.

PAES Management Chronic entrapment can lead to endothelial damage ? ? ? accelerating arthrosclerosis ● Surgery ○ Undamaged popliteal artery : division of abnormal muscle / tendon to release the popliteal artery (Geurgioitis, 2008). ○ Degeneration of popliteal artery: arterial reconstruction (Macedo, 2003). ● Untreated - intraluminal stenosis / aneurysm formation (Frontera et al, 2006). RTP: 6 -8 months postop

Peroneus quartus ● Incidence : 6 -22% ● Origin: Distal lateral fibula ● Descends medial and posterior to the other peroneals ● Insertions: ○ ○ Retrotrochlear eminence of the calcaneus (most common) 5 th metatarsal ○ Peroneal tendons ○ ○ Lateral retinaculum of the ankle Cuboid ● Lateral ankle pain or instability ● Subluxation/ tearing due to overcrowding peroneal retinaculum

Accessory FDL ● Incidence: 2 -8% ● Variable origins: ○ flexor retinaculum ○ tibia ○ fibula ○ soleus ○ fhl ● Posterior and superficial to tibial nerve ● Beneath flexor retinaculum through tarsal tunnel ● Leads to tarsal tunnel syndrome, FHL tenosynovitis

Accessory popliteus ● Common origin with lateral head gastroc ● Passes obliquely through popliteal fossa, anterior to popliteal vessels ● Compresses popliteal neurovascular bundle

Tensor fascia suralis ● Soft tissue mass popliteal fossa ● Very Rare ● “muscular slip passing from one of the hamstrings to the fascia of the back of the leg”

References Anderson & Read, 2008, Popliteal Artery Entrapment Syndrome, Atlas of Imaging in Sports Medicine, Chapter 6, pgs 525 - 526. Barry D. Bothroyd JS, Tensor Fasciae Suralis, J Anat. 1924 Jul; 58(Pt 4): 382– 383. Brukner et al, 2012, Popliteal Artery Entrapment, Clinical Sports Medicine, Chapter 36, pgs 770 - 771 Carroll J, Accessory Muscles of the Ankle, MRI Web Clinic — November 2008, http: //radsource. us/accessory-muscles-of-the-ankle/#sthash. K 41 B 4 Fey. dpuf Christodoulou A, Terzidis I, Natsis K, Gigis I, Pournaras J, Soleus accessorius, an anomalous muscle in a young athlete: case report and analysis of the literature, Br J Sports Med 2004; 38: e 38 doi: 10. 1136/bjsm. 2004. 012021 Frontera, Herring, Micheli, Silver, 2006, Neurovascular Causes of Leg Pain, Clinical sports medicine: medical management and rehabilitation, Chapter 32, page 451, retrieved from http: //www. mdconsult. com/das/book/pdf/443857492 -2/978 -1 -4160 -2443 -9/4 -u 1. 0 -B 978 -1 -4160 -2443 -9. . 50035 -0. . DOCPDF. pdf? isbn=978 -1 -4160 -2443 -9&eid=4 -u 1. 0 -B 978 -1 -4160 -2443 -9. . 50035 -0. . DOCPDF on 21/4/14 Gourgioitis, Aggelakas, Salemis, Elias, Georgiou, 2008, Diagnosis and surgical approach of popliteal artery entrapment syndrome: a retrospective study, Vascular Health Risk Management, 4 (1), pgs 83 -88. Macedo, Johnson, Hallett, Breen, 2003, Popliteal Artery Entrapment Syndrome: Role of Imaging in Diagnosis, American Journal of Roentgenology, Volume 181, Number 5, pgs 1259 -1265, Retrieved from DOI: 10. 2214/ajr. 181. 5. 1811259