- See:
-
Innerv. Musc. Lower Limb
-
Innervation of the Leg and Foot:
- Anatomy:
- common peroneal nerve is derived from (
L4,
L5,
S1,
S2) as a part of the
sciatic nerve;
- posterior component, supplies short head of
biceps femoris in thigh, crosses posterior to lateral head of
gastrocnemius, and becomes subQ behind head of fibula;
- it penetrates the posterior intermuscular septum, and becomes closely opposed to the periosteum of the proximal fibula;
- it then divides into superficial & deep peroneal nerves;
- nerve also gives off a lateral sural cutaneous brach which joins with the the medial sural cutaneous nerve (from tibial nerve) to form the
sural nerve;
- superficial peroneal nerve:
- supplies
lateral compartment of leg, first passing between
peroneus longus
- passes in a straight line from the common peroneal nerve;
- along the length of the proximal one third of the fibula, the superficial peroneal nerve is on the lateral cortex of the fibula;
- passes between peroneus longus &
peroneus brevis;
-
superficial sensory nerves:
- subcutaneous superficial sensory branch lies between peroneus brevis and
EDL msucles.
- superficial peroneal nerve is accompanied by a true vascular axis that is supplied by
tibialis anterior artery along its course.
- about 10-12 cm above the tip of the lateral malleolus, the superficial peroneal nerve pierces the fascia;
- about 6-7 cm distal to the fibula, the superficial peroneal nerve bifurcates into intermediate and medial dorsal cutaneous nerves;
- location of cutaneous nerves: (from Huene and Bunnell 1995)
- branches of the superficial peroneal nerve or the sural nerve may be injured during ORIF of Ankle frx;
- these nerves are most at risk at the junction of the distal and middle thirds of the lateral border of the fibula;
- in 22% of legs, braches of either nerve will cross the frx site;
- in 54% of legs, branches of superficial peroneal will lie within 5 mm of the anterolateral border of the fibula;
- safest interval is 12 mm posterior to anterolateral border of fibula at 10 cm from fibular tip, and 10 mm posterior to anterolateral border at 5 cm proximal to tip;
- references:
-
Surgical anatomy of the superficial peroneal nerve in the ankle and foot.
-
Anatomical variations in the course of the superficial peroneal nerve.
-
Operative anatomy of nerves encountered in the lateral approach to the distal part of the fibula.
- Anatomic relations between ankle arthroscopic portal sites and superficial peroneal and saphenous nerves. A. Saito MD FAI. Vol 19. No 11. Nov 1998. p 748.
- Operative Anatomy of Nerves Encountered in the Lateral Approach to the Distal Part of the Fibula. D.B. Huene MD. JBJS Vol 77-A. No 7. Jul 1995.
- superficial peroneal nerve block:
- provides anesthesia over the superolateral foot;
- in thin patients the nerve can often be visualized by stretching the skin over the dorsum of the foot;
- subcutaneous "field block" with continuous wheal from lateral margin of achilles tendon around anterior ankle to the medial margin of the achilles tendon
will anesthetize all superficial nerves of the foot: superficial peroneal, saphenous, and sural;
- references:
-
NYSORA.
-
Anesthesia UK.
- deep peroneal nerve:
- courses anteriorly around fibula, taking a sharp turn as it rounds the fibular neck, to enter
anterior compartment of leg;
- because of the sharp turn, the nerve is more tethered than the superficial branch;
- immediately below the fibular head, the deep peroneal nerve lies on the anterior cortex of the fibula for a distance of 3-4 cm;
- nerve passes under the intermuscular septum (between
lateral and anterior compartments) which is a point of entrapment;
- note that when this septum is pulled taunt, it compresses the deep peroneal nerve w/o affecting the superficial nerve;
- it supplies
anterior compartment muscles as it travels w/ the the anterior tibial artery, lying between the tibialis anterior and the
EHL;
- it passes underneath extensor retinaculum, sends a motor branch to
EDB, and finally sends a sensory branch to the interspace between the first and second toes;
- references:
-
Palsy of the deep peroneal nerve after proximal tibial osteotomy. An anatomical study.
-
Relationship of the common peroneal nerve and its branches to the head and neck of the fibula.
- deep peroneal nerve block:
- provides anesthesia over the first webspace, with some deep contribution to joints of the lesser toes;
- From medial to lateral: EHL, Dorsalis pedis artery,
Deep Peroneal Nerve, EDL;
- 2-3 cm distal to intermalleolar line, inject just above bone, between EHL and DP pulse;
- references:
-
NYSORA.
-
Anesthesia UK.
- Peroneal Nerve Palsy:
-
peroneal palsy following TKR
-
nerve injury
-
discussion:
- peroneal nerve palsy may lead to severe disability w/ foot drop and paresthesias;
- note that in contrast to other types of nerve palsies, peroneal palsy may demonstrate a greater motor deficit (than sensory
deficit) because the deep motor brach is subject to tethering a two points: the fibular neck and the intermuscular septum;
- traumatic peroneal palsy: may result from
supracondylar frx,
knee dislocation, and
proximal tibial frx;
- atraumatic peroneal nerve palsy:
- may result from a large
fabella which impinges on peroneal nerve behind the
knee or may result from a proximal tibiofibular synovial cyst (which is identifed by MRI);
- these patients will often have a history of lumber disc disease, ETOH use, and diabetes.
- references:
- Unusual manifestations of proximal tibiofibular joint synovial cysts. TA Damron, MG Rock. Orthopedics. Vol 20, 1997. p 225-230.
- exam:
- always consider lumbar radiculopathy during the examination;
- there may be an obvious foot drop;
- sensory loss may be difficult to determine because of variable & small autonomous zone of sensation;
- Tinel's sign over the fibular neck, helps localize the site of nerve compression;
- always check for a fabella and check to see if direct compression reproduces nerve symptoms;
- in cases of knee dislocation it is important to test for function of the tibial branch of the sciatic nerve as well;
- in some cases of peroneal nerve avulsion, there will also be a sciatic nerve traction injury;
- EMG:
- useful to objectively document the conduction block;
- if possible should be performed w/ in one month of injury;
- amplitude of the sensory potential and decreases in nerve conduction velocities are used to confirm sensory and motor deficits, respectively;
- prognosis;
- w/ partial nerve palsy, > 80% will recover completely;
- w/ complete palsy, < 40% will have complete recovery;
- peroneal nerve in continuity which arises from a well defined etiology will tend to do better than nerve palsies arising from idiopathic causes;
- treatment:
- if there is no neurologic improvement after 2-3 months, then operative decompression is indicated;
- nerve in continuity:
- operative treatment invovles external neurolysis of peroneal nerve at the level of the fibular head;
- the nerve and its branches need to be freed from its adherence to the proximal fibula, particularly at its most proximal
4 cm as well as a 2nd region of adherence which may lie between 7 and 15 cm from the fibular head;
- the nerve may be entrapped by thick fibrous bands which arch over the nerve as it crosses the fibular neck;
- the arch has a superficial band and a deep band;
- nerve not in continuity: (
neurotomesis)
- see
nerve repair
- one of the problems encountered in peroneal nerve repair following knee dislocations
(or other injuries) is that the location of the nerve injury may be well above the knee joint;
- in the case of knee dislocation, there may be concomitant tibial nerve division palsy;
- references:
-
Nerve grafting for traction injuries of the common peroneal nerve. A report of 17 cases.
-
Nerve grafting for traction injuries of the common peroneal nerve. A report of 17 cases.
-
The operative treatment of peroneal nerve palsy. MA Mont et al. JBJS Vol 78-A. 1996. p 863-869.
-
Decompression of the common peroneal nerve: experience with 20 consecutive cases.
- Fibular fibrous arch. Anatomical considerations in fibular tunnel syndrome. H Goobe and D Chain. Acta Anat. Vol 85. 1973. p 84-87.
-
Anatomic variations related to decompression of the common peroneal nerve at the fibular head.
-
Posterior Tibial Tendon Transfer: Results of Fixation to the Dorsiflexors Proximal to the Ankle Joint
Peroneal nerve repair. Surgical results.
Peroneal nerve palsy after early cast application for femoral fractures in children.
Anatomic considerations of pin placement in the proximal tibia and its relationship to the peroneal nerve.
Peroneal nerve entrapment.
T. Fabre MD et al. JBJS. Vol 80-A. No 1. Jan 1998. p 47.
Anatomic Location of the Peroneal Nerve at the Level of the Proximal Aspect of the Tibia: Gerdy's Safe Zone.
New tendon transfer for correction of drop-foot in common peroneal nerve palsy.
