Discussion:
- peroneal nerve
- 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 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.
- reference:
- Unusual manifestations of proximal tibiofibular joint synovial cysts.
- 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;
- 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;
- 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.
- The operative treatment of peroneal nerve palsy.
- Decompression of the common peroneal nerve: experience with 20 consecutive cases.
- Fibular fibrous arch. Anatomical considerations in fibular tunnel syndrome.
- Anatomic variations related to decompression of the common peroneal nerve at the fibular head.
- Tendon Transfers:
- Posterior Tibial Tendon Transfer: Results of Fixation to the Dorsiflexors Proximal to the Ankle Joint
- Combined anteroposterior tibial tendon transfer in post-traumatic peroneal palsy.
- Anterior transplantation of the posterior tibial tendon for persistant palsy of the common peroneal nerve.
- Early Active Motion versus Immobilization after Tendon Transfer for Foot Drop Deformity: A Randomized Clinical Trial