Peroneal Nerve Injury and Foot Drop
Peroneal (fibular) nerve injury is a common peripheral nerve compression or injury of the lower limb. Its most prominent sign is 'foot drop', in which dorsiflexion of the foot (lifting the foot upward) cannot be performed. Treatment varies with cause and severity of injury; relieving compression, an ankle-foot orthosis (AFO), physiotherapy and, in selected cases, surgery (decompression, nerve or tendon transfer) are used.
Përditësimi i fundit: 2026-06-07
Definition and Anatomy
The peroneal nerve (fibular nerve) is one of the two main branches of the sciatic nerve. It runs from behind the knee laterally and downward, winding around just below the head of the fibula; at this point it runs superficially under the skin and over the bone, making it highly exposed to trauma and pressure. Here it divides into deep and superficial branches. The deep peroneal nerve provides foot and toe dorsiflexion (tibialis anterior, extensor muscles), while the superficial peroneal nerve provides foot eversion (peroneus longus/brevis) and carries sensation from the dorsum of the foot. Foot drop is the downward drooping of the foot due to loss of dorsiflexion.
Causes and Risk Factors
The most common cause is compression at the level of the fibular head: prolonged leg crossing, prolonged bed rest, a cast or external pressure, or rapid weight loss (reduction of protective fat). Other causes include traumatic injuries (knee/leg fractures, lacerations), complications of surgery (knee surgery, total knee replacement), compression by a mass (ganglion or Baker's cyst, tumour), diabetes mellitus and systemic neuropathies. The severity of nerve injury is classified as neurapraxia (transient conduction block), axonotmesis (axonal disruption with the sheath preserved) and neurotmesis (complete transection).
Symptoms
The main sign is foot drop: inability to lift the foot upward and dragging of the toes during walking. To compensate, the patient walks by lifting the hip and knee excessively (steppage gait). Weakness of toe extension and foot eversion and a tendency to ankle sprains may be seen. In long-standing injury, atrophy of the anterior leg muscles develops. Sensory findings are less prominent than motor findings; numbness and tingling may occur on the lateral dorsum of the foot. An important distinguishing finding is preserved plantarflexion (pushing off on the toes), which indicates that the tibial nerve is intact.
Diagnosis
Diagnosis is made by clinical examination and electrophysiological tests (EMG/nerve conduction studies). On examination, dorsiflexion weakness, steppage gait and preserved plantarflexion are assessed; tapping over the fibular head may produce distally radiating paraesthesia (Tinel's sign). EMG/NCS localise the injury (fibular head), determine its type (neurapraxia/axonotmesis) and severity, and are used to monitor recovery. Imaging (MRI, high-resolution ultrasound) may be performed to investigate the source of compression or lumbar MRI to assess L5 radiculopathy. The differential diagnosis includes L5 radiculopathy (usually accompanied by leg pain, with paraspinal denervation on EMG), sciatic nerve injury and hereditary neuropathies such as Charcot-Marie-Tooth disease.
Conservative Treatment
Conservative treatment is the first choice. The source of compression is removed (change of position, loosening of the cast) and any accompanying diabetes is controlled. Physiotherapy is critical: passive range-of-motion exercises and Achilles tendon stretching prevent contracture; active strengthening is added once recovery begins; functional electrical stimulation may reduce muscle atrophy. In moderate-to-severe foot drop, an ankle-foot orthosis (AFO) provides safe walking and prevents falls and contracture. The recovery time depends on the type of injury; neurapraxia recovers within weeks, axonotmesis within months (regeneration of about 1 mm/day). If there is no recovery within a defined period, surgery is considered.
Surgical Treatment
Surgery is considered in chronic compression unresponsive to conservative treatment, progressive injury, complete nerve transection (neurotmesis), compression by a mass, or persistent foot drop. Options include peroneal nerve decompression (release of the nerve at the fibular head and neurolysis), nerve repair or nerve grafting for traumatic transections, nerve transfer in proximal/late cases (for example from a branch of the tibial nerve to the deep peroneal nerve), and tendon transfer in permanent injury (most commonly transferring the tibialis posterior tendon to the dorsum of the foot). Tendon transfer provides functional improvement and may reduce the need for an orthosis in suitable cases. The timing of nerve surgery (before muscle atrophy develops) determines the outcome.
Prognosis
The prognosis depends on the type, duration and cause of the injury. In neurapraxia, recovery is usually complete; in axonotmesis, partial or full recovery occurs depending on distance and time; in neurotmesis there is no spontaneous recovery and surgical repair is required. Early diagnosis, removal of compression and physiotherapy markedly improve the prognosis. A subset of patients may be left with permanent weakness and may require a continuous orthosis or tendon transfer. The treatment plan is individualised for each patient, and no outcome can be guaranteed in advance.
Burimet
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Ky artikull ka karakter të përgjithshëm informues dhe nuk zëvendëson vizitën mjekësore. Vendimet për diagnozën dhe trajtimin janë individuale.