Lower limb Entrapment
Syndromes
Dr Andre Vlok
Orthopaedic Department
Kalafong hospital
2012
Compression neuropathies
• Normal nerves are subjected to both stretching
and compression, but when the norms,
excursion is restricted or there is persistent
compression, irritation of the nerve follows with
eventual altered microcirculation and fibrosis.
• This all leads to impaired nerve conduction
• There are certain anatomic areas where nerve
are more valuable to compression.
Areas where nerves are at risk

Where a nerve goes through a “tunnel" or potential
tunnel ( muscle arch). Not confined to this eg tumor or
fracture
too small – osteophytes, displaced fractures or
dislocations.
 Contents too much for tunnel – synovitis, ganglion,
aneurysm or tumor etc.
 Tunnel
Nerve up against bone: Peroneal or ulnar nerve.
Fluid retention: pregnancy, renal failure, obesity
Double crush syndrome
Compression syndromes



Compression of a
peripheral nerve once
it has left the spinal
canal.
Can be compressed
by any structure
internally or
externally.
In many cases no
cause is found
Compression of the Sciatic nerve
Double crush syndrome
 Nerve
compressed in
more than one place
making it more
sensitive to
compression in another
area.
 Carpal
tunnel and
cervical disc lesion.
Principles of nerve compression
Clinical picture will depend on the nerve involved.
 Sx are usually progressive if the cause is not addressed
 Neurological fall out:

 Sensory
loss
 Motor loss
 Mixed – motor and sensory
 Reflexes may be decreased or absent.
 Features of LMN lesion – muscle wasting, decreased tone and
reflexes as well as muscle atrophy.
 Signs elicited by provocative tests - Tinnel (stretching of nerve)
 EMG - can be helpful in some cases only.
Principles of nerve compression
Always look for proximal causes – spine or
hip etc. (Double crush)
 Associated systemic pathology – DM,
alcoholism, hypothyroidism, renal failure.
 Vascular disorders can simulate nerve
compressions.
 Usually chronic disorder but may be due
acute injury – Sciatic nerve compression
associated with hip dislocation.

Sensory patterns
Nerve pattern
Dermatomal pattern
Presenting features: HISTORY
Sensory: numbness, tingling and
sometimes burning sensation in distribution
of nerve
 Motor: weakness to paralysis. Hx of
stumbling, giving away or clumsiness
 Sx: may fluctuate but condition is usually
progressive

Presenting features: CLINICAL Fx
Skin: dry/pale
 Sensory loss
 Muscle weakness
 Decreased reflexes


Features of a LMN
Nerve compressions in the lower limb

Not as common as in upper limb.
paraesthetica – LCNT
 Femoral nerve *
 Peroneal nerve – Common, Deep or Superficial
 Tibial nerve – Tarsal syndrome.
 Sciatic nerve – Piriformis syndrome.
 1st branch of lateral plantar nerve
 Saphenous nerve *
(* rare)
 Meralgia
Lateral Cutaneous nerve of the thigh
(Meralgia Paraesthetica)





Entrapment of LCNT by the
inguinal ligament & fascia.
Common ++
Associated with: obesity,
pregnancy, trauma (seat belt),
surgery to the area, belt.
Burning sensation in
distribution of nerve – lat
aspect of thigh. Numbness.
Extension > Sx
Meralgia paraesthetica
Treatment

Conservative:




Diagnostic test –
infiltration of the area with
lignocaine and cortisone.
If Sx abate then
diagnostic (and Rx).
NSAIDS, Neurontin
Most resolve after 2-3
months.
Surgery if Sx persist - cut
tunnel open
Peroneal nerve syndromes
3
patterns found:
Common peroneal
Deep Peroneal
Superfical Peroneal
Lesion affects gait - Drop foot gait,
<eversion of foot or both
Pain and paraesthesia and
weakness. Pain is not prominent.
 Causes:
Fracture
fibula neck / tumor /
osteophytes
Compression – caliper, POP,
position of leg – in OR, ward or
traction.
Strawberry pickers knee
Common Peroneal
Compressed at fibular tunnel.
 Pain, (usually not significant) and
weakness of lower leg
 Tinnel over the nerve
 Loss of power to all anterior and peroneal
compartments (TA, EHL, EDL, PL, PB, PT)
 DROP FOOT and cannot evert foot or
extend toes.

Common Peroneal nerve – fibular
tunnel syndrome
Drop foot
Splint
Drop foot
Deep Peroneal nerve

Sensory: loss of sensation on
dorsum of foot between big toe and
second toe.

Pain in foot and particularly with
activities and sport
Deep Peroneal lesion
Motor fallout not
common.
 If present:
 They can evert foot
but cannot extend
toes, no TA function very weak
dorsiflexion.
 If distal lesion then
no weakness found.

Superficial Peroneal nerve
Superficial peroneal
 Motor fall out is rare.
 Cannot evert foot but can
dorsiflexion foot and extend toes
(deep peroneal n. intact)
 Loss of sensation on dorsum of foot
- sometimes pain.
 Running, walking and squatting
aggregates sx.

Treatment
Conservative:
remove cause if one found.
Drop foot splint to prevent
equinus.
NSAID & analgesia
If improving continue monitoring

Surgery:
After 3-4 months failed
conservative treatment

Surgical options

Release of compressing
structures.
If no nerve recovery then
tendon transfers or
fusions of certain joints can
be done to improve function.


Objectives of treatment
• Relieve compression
• Monitor recovery of nerve
• Keep and maintain the
plantegrade position of the
foot
• Splinting
• Tendon transfer
• Fusion of ankle - foot
Tarsal Tunnel Syndrome
Tibial nerve Syndromes


There is a fibro-osseous
tunnel with N A V
Nerve divides into divisions
in the tunnel:
 Med
and Lat plantar nerves
 Calcaneal branches
 1st branch of lat. Plantar n.

Causes:
– ankle#
 Rheumatoid arhtritis
 Tight fitting shoes
 Trauma
Tibial nerve syndrome cont.
Vague paraesthesia
over plantar surface of
foot.
 Pain over sole of foot.
 Sx worse at night and
standing
 Atrophy of abductor
hallucis.
Dorsiflexion –
eversion test can
precipitate Sx.

Dorsiflexion - eversion
Treatment
Conservative:
Splint or POP (below –
knee cast) 3 to 4 weeks.
NSAIDS and analgesia.
Surgery;
Only considered after
conservative treatment has
failed.
Tunnel is decompressed.
st
1





branch of Lat. Plantar nerve.
Known as Baxter’s n.
Medial heel pain and
referred pain lat. aspect
of foot.
15% caused by plantar
fasciitis.
Cause of heel pain in
20% of patients.
Sx similar to plantar
fasciitis
Baxter’s
nerve
Piriformis syndrome




Irritation of the sciatic
nerve.
Pain or paraesthesia
down posterior aspect of
leg – Sciatica. If severe
may also have
weakness.
All motor function below
the knee – not all
sensory function.
Exclude diagnosis