Stemcelldoc's Weblog

June 15, 2013

Understanding Peroneal Nerve Entrapment: Lateral Knee Pain and Weakness

At the Centeno-Schultz Clinic identifying the source of your knee pain and weakness is critical. There are many causes of lateral knee and leg pain. Entrapment of the peroneal nerve as it crosses the fibular head is discussed below.

ANATOMY REVIEW
The sciatic nerve, largest nerve in the body divides into the tibial and common peroneal nerve just above the level of the knee-joint (popliteal fossa).

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The common peroneal nerve travels laterally and courses around the fibular neck and passes through an opening in the  peroneus longus muscle. This opening can be quite tough and can result in the nerve angulating through it at an acute angle.

common_peroneal_nerve_entrapment

PREVALANCE

Peroneal nerve injuries are the most common peripheral nerve injuries of the lower limb to result from multiple traumatic injuries.  While the nerve can be injured at any site along its path, most peroneal nerve injuries occur at the region of the fibular head.

COMMON CAUSES

Habitual leg crossing

Trauma

Prolonged squatting (strawberry picker’s palsy)

Knee dislocation

Total knee and hip replacement and arthroscopies

PRESENTATION

ALTERED GAIT secondary to weakness or paralyzed muscles that control ankle extension (ankle dorsiflexors).  This can result in foot drop foot where dorsiflexion of the foot is compromised and the foot drags during walking.

PAIN

LOSS OF SENSATION over the lateral knee and leg.

Peroneal Nerve Sensory Distribution

Peroneal Nerve Sensory Distribution

At the Centeno-Schultz Clinic MSK Ultrasound is an essential part of the diagnostic evaluation and allows for direct visualization of platelets and stem cells therapies.

Below is an ultrasound image of the common peroneal nerve at the level of the fibular head.  The nerve is seen on cross-section and identified by the white arrow.  fh=fibular head and lhg is lateral head of gastrocnemius, a major muscle in the calf.

common peroneal nerve ultrasound

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