1. Lower limb Entrapment Syndromes
Dr Andre Vlok
Orthopaedic Department
Kalafong hospital
2012

2. 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.

3. 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
Tunnel too small – osteophytes, displaced fractures or dislocations.
Contents too much for tunnel – synovitis, ganglion, aneurysm or tumor etc.
Nerve up against bone: Peroneal or ulnar nerve.
Fluid retention: pregnancy, renal failure, obesity
Double crush syndrome

4. 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

5. Compression of the Sciatic nerve

6. 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.

7. 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.

8. 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.

9. Sensory patterns
Nerve pattern
Dermatomal pattern

10. 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

11. Presenting features: CLINICAL Fx
Skin: dry/pale
Sensory loss
Muscle weakness
Decreased reflexes
Features of a LMN

12. Nerve compressions in the lower limb
Not as common as in upper limb.
Meralgia 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)

13. 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

14. Meralgia paraesthetica

15. 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

16. 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

17. 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.

18. Common Peroneal nerve – fibular tunnel syndrome

19. Drop foot
Splint
Drop foot

20. 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

21. 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.

22. Superficial Peroneal nerve
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.

23. Treatment Surgical options Surgery:
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.

24. 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

25. Tarsal Tunnel Syndrome

26. 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:
Trauma – ankle#
Rheumatoid arhtritis
Tight fitting shoes

27. 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

28. Treatment Conservative: Surgery;
Splint or POP (below – knee cast) 3 to 4 weeks.
NSAIDS and analgesia.
Surgery;
Only considered after conservative treatment has failed.
Tunnel is decompressed.

29. 1st 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

30. 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