Leg Pain: An Introduction

In addition to fractures, strains and sprains, pain just above the instep can be due to an occult injury to the fibular nerve either near the ankle or higher up, just below the knee. Diagnosis is usually suspected on the basis of history. Nerve conduction tests are rarely necessary, unless the patient fails to respond to standard therapy.

Leg pain describes a large and varied group of conditions. Like in so many other areas it is important to distinguish intrinsic leg pain (pain arising directly from the tissues of the leg) from referred leg pain. Referred leg pain often will have a component of the pain which is outside of the leg, most commonly in the lower back, but occasionally will present as isolated hip pain, knee pain or foot pain making the diagnosis a bit more difficult.

Causes of intrinsic leg pain include arthritis involving one or more of the major joints of the leg, muscular strains or ligamentous sprains, meniscal tears of the knee, occult fractures, infections or tumors. Vascular problems such as Peripheral Arterial Disease (PAD) can lead to pain on walking or other activity (claudication). Here it is important to distinguish between ischemic claudication and neurogenic claudication.

Extrinsic causes of leg pain include lumbar radiculopathy, injuries to the lumbar plexus or to individual peripheral nerves. A common example of the latter is meralgia paraesthetica, which often presents as an isolated stripe of pain along the lateral thigh and results from irritation of the lateral femoral cutaneous nerve.

While not technically extrinsic to the leg there are a number of neuropathic pain states that result from injury to small nerves within the leg. These are often difficult to diagnose because there are no areas of obvious tissue damage or numbness or weakness. Diagnosis can often be suspected on the basis of a careful history and the knowledge that the pain follows the distribution of a peripheral nerve or a portion thereof. It is important to make this diagnosis because I have seen a number of patients who have undergone unnecessary operations looking for an intrinsic cause of their pain.

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