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

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

3. 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)
Presentation usually during adolescence with muscle strain, tendinopathy, compartment syndrome or posterior tibial nerve compression
Thought to be due to rapid growth / hypertrophy and muscle activity at adolescence causing ischemic pain from compartment type phenomenen or due to compression of the post tibial nerve / traction phenomenum on the nerve.

4. X-ray : soft tissue swelling btw deep compartment & Achilles
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
MRI : no difference btw those with and without symptoms

5. Popliteal Artery Anatomical Variations 50% Normal:
Btw heads of gastroc
Posterior to popliteus
a) Anatomical PAES is caused by variation in the anatomical relationship between the popliteal artery and the medial head of gastroc as it exits the popliteal fossa, (Brukner, 2012). The most common variation is where the accessory part of medial gastroc exits behind the popliteal artery, (Brukner, 2012). Whelan in 1984 classified anatomical PAES, into 5 types;
Type 1: Medial head of gastroc displaces the popliteal Artery medially and is the most common type accounting for 50% of cases, (Anderson & Read, 2008).
Type 2: Variable anomalous origin from the lateral surface of the Medial femoral condyle, due to arrested migration of the Medial head of gastroc, (Anderson & Read, 2008)
Type 3: Popliteal Artery develops in the muscle mass
Type 4: Popliteal Artery develops deep to popliteus
Type 5: Popliteal Artery and vein are involved (Anderson & Read 2008).
b) Functional PAES occurs due to a hypertrophied gastrocnemius muscle which causes compression of the popliteal artery between gastroc and bone in dorsiflexion resulting in symptoms, (Frontera et al, 2006).

6. PAES Presentation: 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
Prolonged contraction phase with walking

7. PAES Investigation Doppler U/S Dynamic and symptomatic MRI/MRA:
relationship between structures
Angiography
CT Angiography:
site of occlusion/ ddx/ anat variants.
U/S: High false +ve rate in athletes
MRI: shows rel btw structures - abnormal physiology and anatomy
Angiography - Narrowing unlikely to show cause - invasive.
CTA: site of occlusion/ abnorm anat/ differentials

8. 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

9. 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)
5th metatarsal
Peroneal tendons
Lateral retinaculum of the ankle
Cuboid
Lateral ankle pain or instability
Subluxation/ tearing due to overcrowding peroneal retinaculum

10. Accessory FDL Incidence: 2-8% Variable origins: fhl
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

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

12. 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”

13. References
Anderson & Read, 2008, Popliteal Artery Entrapment Syndrome, Atlas of Imaging in Sports Medicine, Chapter 6, pgs
Barry D. Bothroyd JS, Tensor Fasciae Suralis, J Anat Jul; 58(Pt 4): 382–383.
Brukner et al, 2012, Popliteal Artery Entrapment, Clinical Sports Medicine, Chapter 36, pgs
Carroll J, Accessory Muscles of the Ankle, MRI Web Clinic — November 2008,
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:e38 doi: /bjsm
Frontera, Herring, Micheli, Silver, 2006, Neurovascular Causes of Leg Pain, Clinical sports medicine: medical management and rehabilitation, Chapter 32, page 451, retrieved from &eid=4-u1.0-B 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
Macedo, Johnson, Hallett, Breen, 2003, Popliteal Artery Entrapment Syndrome: Role of Imaging in Diagnosis, American Journal of Roentgenology, Volume 181, Number 5, pgs , Retrieved from DOI: /ajr