24 Pain in the Lower Extremity in Adults
To diagnose pain in the lower extremity accurately, the physician must determine whether the pain is articular (hip, knee, or ankle) or nonarticular (muscular, vascular, or neurologic). In addition, the examiner should note whether the pain is present at rest or is primarily associated with exercise. The most likely causes of pain in a child’s leg are different from those in an adult. Therefore, lower extremity pain in adults and lower extremity pain and a limp in children are reviewed in separate chapters.
In adults the most common causes of leg pain are muscular and ligamentous strains; degenerative joint disease (DJD), particularly of the hip and knee; intermittent claudication due to arterial insufficiency; spinal stenosis; sciatica; night cramps; varicose veins; thrombophlebitis; gout; and trauma. The major clues to diagnoses are as follows:
The most common cause of leg pain in adults is muscular or ligamentous strain, seen more frequently in “weekend athletes.” Questioning usually reveals a history of unusual or strenuous exercise. The usual causes of leg pain in joggers and runners are shin splints, stress fractures, and compartment syndromes. The most common is shin splints, a musculotendinous inflammation of the anterior tibia that occasionally involves the periosteum. The pain is usually on the anterior aspect of the tibia, particularly the distal third along the medial crest, but it can occur on the lateral aspect of the tibia as well. Shin splints are most common in less well-conditioned athletes and are most frequently reported early in the running season. Skiers often experience anterior knee pain due to patellofemoral problems.
Anterior knee pain due to abnormal patellar tracking is more common in women and adolescents. Patellar problems are more common in young women, often beginning in adolescence. During pregnancy the common causes of painful legs include venous insufficiency, postphlebitic syndrome, thrombophlebitis, muscle cramps, and trauma. Patients who kneel frequently (carpet installers and floor washers) often have prepatellar bursitis.
DJD is uncommon in patients younger than 40 years unless it has been facilitated by unequal leg length (causing DJD of the hip) or prior trauma, such as athletic injuries of the knee. After age 40, pain in the hip or knee is typically caused by DJD. Sports injuries, including trauma, ligamentous sprains and tears, meniscal tears, and overuse syndromes, are also more common in adults older than 40 years. Inflammatory arthritis includes rheumatoid arthritis, septic arthritis, and gout. Osteoarthritis and Baker’s cyst occur more frequently in older adults.
In patients age 50 or older, calf pain precipitated by walking or exercise that abates with rest is most likely from peripheral arterial insufficiency (peripheral artery disease). Pain in the hip from intermittent claudication is seen in patients with aortoiliac disease. When exercise-induced calf pain occurs in younger adults, frequently with a history of phlebitis, venous claudication is probable. Gout is most common in older men but can occur in women, particularly those who have had early menopause (natural or surgically induced). Patients with gout may or may not have a family history of the condition. Often a history of a prior attack can be elicited. Classic gouty pain occurs in the big toe, but it may occur in other toes or the ankles or knees; it is rare in the hip.
Anterior knee pain is most often caused by patellar tendinitis, patellofemoral malalignment, or chondromalacia patellae (also known as anterior knee pain syndrome). Pain due to patellofemoral malalignment is usually aching in quality, has a gradual onset, and is located in the peripatellar region. It is often bilateral and is worse with activity such as stair climbing, hill climbing, skiing, and squatting and after prolonged sitting. Sharp pain in the knee, particularly the medial aspect, suggests synovial impingement or structural difficulties such as loose bodies. Aching joint pain is usually seen in inflammatory conditions with diffuse involvement of the synovium, such as those found in rheumatoid arthritis.
When the knee or hip joints are painful and stiff in the morning, improve during the day, and worsen toward the end of the day, DJD is probable. Osteoarthritis (DJD) usually occurs in older patients but may occur earlier under special circumstances. These pains may be exacerbated by certain activities (e.g., descending stairs). Patients with osteoarthritis of the hip may present with pain in the groin or the knee. Therefore, the diagnosis of DJD of the hip must be considered in patients who present with knee or groin pain when no pathology is noted in these areas. With DJD of the hip, hip motion is usually restricted and radiographic findings are abnormal. Obturator nerve involvement can also cause pain in the groin and medial aspect of the thigh and knee. A hernia may be suspected because of groin pain; if no hernia is found, obturator involvement should be considered.
Osteoarthritis of the hip may also manifest as pain in the buttock; therefore, the causes of buttock pain must be considered in the differential diagnosis. Buttock pain caused by lumbar disk disease is worse with extension of the spine and relieved by rest in the fetal position. Buttock pain caused by osteoarthritis of the hip is not usually exacerbated by spinal extension or relieved by rest in the fetal position. Likewise, no evidence of nerve root compression is usually seen with osteoarthritis of the hip.
Typical sciatica causes pain in the buttock that radiates down the posterolateral aspect of the leg. It may radiate into the dorsum of the foot and tends to follow standard dermatome patterns. Sciatic pain may be sharp or burning. It is frequently made worse by coughing, straining at stool (if sciatica is caused by a herniated disc), or walking down steps; it may be precipitated by sudden strenuous movements. The patient may present with pain initiated by an attempt to lift a heavy object or by vigorous turning or twisting with the back flexed (e.g., pulling the rope on a lawn mower or outboard engine).
The pain of arterial insufficiency (intermittent claudication) is usually described as soreness, a cramp, or a burning sensation in the calf. The discomfort may also be described as tightness, heaviness, tiredness, or achiness rather than pain. The discomfort is usually precipitated by walking and relieved by rest. It rarely occurs while the patient is at home. It usually develops after the patient has walked a predictable (by the patient) distance and is relieved by rest in a standing position after a predictable (by the patient) time. After resting, the patient can resume walking a similar distance before the pain starts again; relief is achieved again after resting.
A common mistake is the diagnosis of osteoarthritis of the hip when gluteal claudication is the problem. This error is more likely if buttock pain is not associated with pain in the calf. Some patients with vascular disease of the iliac artery complain only of the symptoms of gluteal claudication, which are usually felt when the patient walks outside.
The leg of a patient with arterial insufficiency may have pallor on elevation, rubor on dependency, and loss of hair on the toes. Some men with aortoiliac disease may present with pain in the upper leg or the buttock and an inability to develop or sustain an erection. Pain from intermittent claudication is usually unilateral but can be bilateral. When the pain is present bilaterally, it seldom occurs in both legs simultaneously. The onset of pain in one leg may prevent the patient from walking enough to produce symptoms in the other leg. Physical examination for evidence of arterial insufficiency must therefore be performed on both legs. Comparing the blood pressure of the ankle and the arm provides the ankle-brachial index (ABI). An ABI less that 0.9 is abnormal. An ABI less than 0.4 is suggestive of severe peripheral artery disease.
Venous claudication is difficult to distinguish from claudication due to arterial insufficiency. In both conditions, walking causes calf pain that may be severe enough for the patient to stop walking. Patients with venous claudication usually have no physical signs of arterial insufficiency.
Spinal stenosis is another cause of leg pain that is exacerbated by exercise. The pain (pseudoclaudication) is similar to that associated with arterial insufficiency; it also occurs more frequently in older men. The first clue that the pain in the leg is not caused by arterial insufficiency is the presence of normal pedal pulses. Although both begin with exercise, the pain of spinal stenosis is less often relieved by rest than the pain of arterial insufficiency (Table 24-1). The pain of intermittent claudication is relieved within a few minutes, whereas the pain of spinal stenosis requires 10 to 30 minutes to subside. Some patients with calf pain from spinal stenosis state that they must sit or lie down with the thighs flexed to relieve the discomfort.
|VASCULAR CLAUDICATION||NEUROGENIC CLAUDICATION|
|Backache||Uncommon; occurs in aortoiliac occlusion||Common but need not be present|
|Leg symptoms||Quantitatively related to effort||May be brought on by effort; directly related to posture of extension of spine|
|Quality||Cramplike, tight feeling; intense fatigue; discomfort; pain may be absent||Numbness, cramplike, burning, paresthetic; sensation of cold or swelling; pain may be absent|
|Relief||Rest of affected muscle group||Rest not enough; postural alteration of spine to allow flexion is necessary in most|
|Onset||Simultaneous onset in all parts affected||Characteristic march up or down legs|
|Urinary incontinence||Does not occur||Very rare|
|Impotence||Common in aortoiliac disease (failure to sustain erection)||Very rare (failure to achieve erection)|
|Wasting of legs||Global in aortoiliac disease||Cauda equina distribution in severe cases|
|Trophic changes||May be present; absent in aortoiliac disease||Absent but may be present in combined disease|
|Sensory loss||Absent||Not uncommon; common after exercise|
|Ankle jerks||Often absent in patients > 60 yr old||Common, particularly after exercise|
|Straight-leg raising||Full||Often full|
From DeVilliers JC: Combined neurogenic and vascular claudication. SA Med J 57:650-654, 1980.
The pain of spinal stenosis is caused by localized narrowing of the spinal canal due to a structural abnormality that results in cauda equina compression. Patients occasionally complain of backache or buttock pain as well as numbness and tingling in the feet with walking. Walking uphill is easier than walking downhill for these patients. They have no problem riding a bicycle, probably because the stooped position assumed during this activity reduces the amount of cauda equina compression. The examiner must remember that vascular claudication and spinal stenosis can coexist.
Unilateral pain and swelling in the calf are usually caused by thrombophlebitis. The pain is usually present at rest and is seldom worsened by exercise. In a patient with thrombophlebitis who experiences calf pain while walking, acute exacerbation of the calf pain occurs immediately after the foot is placed on the ground. Although the history and physical examination of thrombophlebitis are well known to most physicians (i.e., pain, swelling, tenderness on palpation, occasionally a history of prior trauma or previous bouts of phlebitis), this relatively common cause of leg pain is often misdiagnosed. Several studies have suggested that venous ultrasonography should be used to confirm the clinical diagnosis because thrombophlebitis has often been incorrectly diagnosed in the absence of ultrasonographic evidence.