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 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

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. 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)

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 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 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.

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: Trauma – ankle# Rheumatoid arhtritis Tight fitting shoes

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: 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.

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

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