I. Problem/Condition.
Pain in the lower extremity, including hip, thigh, knee, lower leg, ankle and foot pain.
II. Diagnostic Approach.
A. What is the differential diagnosis for this problem?
When evaluating a hospitalized patient with lower extremity pain, there are several questions one must ask. The first, and most important of these is: Has the patient sustained recent trauma? Recent trauma (e.g., falls to the ground, syncope, falls from bed) will change the evaluation of these patients dramatically. This includes patients who are unable to describe periods of time, such as alcohol withdrawal, etc. In terms of urgency of diagnosis and management of lower extremity pain, the clinician must consider a recent fracture. To evaluate this, if there is any question of possible fracture, radiographs should be taken.
If radiographic evaluation reveals no fracture, but there is high suspicion, the clinician should consider more advanced imaging, including a computed tomography (CT) scan or magnetic resonance imaging (MRI). In some instances, a non-displaced fracture that is less than 3 to 5 days old may appear negative on a radiograph, so further evaluation may be warranted. If fracture is identified, an orthopedic consult is generally warranted for the hospitalized patient.
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The second question one should ask when evaluating the hospitalized patient with lower extremity pain is: Is the pain articular or non-articular? This will help the clinician identify the possible source of he pain. For example, a deep groin pain that worsens with internal or external rotation of this hip may be arthritis or avascular necrosis of the hip, while the absence of these findings with lateral pain of the upper thigh to palpation may be a simple trochanteric bursitis.
The third question to keep in mind is: What is the underlying cause of the pain? The differential diagnosis for pain is long, and for the purposes of brevity, this chapter will focus mainly on the focal musculoskeletal causes of lower extremity pain. However, one must always consider the broad categories of infectious, inflammatory, vascular and neoplastic causes of pain. While a septic knee is rarely a subtle finding, the hospitalized patient may have many sources of infection. Similarly, a patient with large swollen legs from fluid overload may have stretching of their skin from the edema that can cause pain. A patient with a clot on an indwelling catheter may infarct part of an extremity, and can be in significant pain before other signs may be noticed.
With these three questions in mind, we can consider the lower extremity in several parts: the pelvis and hip joint, the thigh, the knee, the lower leg, the ankle and the foot.
B. Describe a diagnostic approach/method to the patient with this problem.
Hip and pelvic pain: (see hip and pelvic pain)
The thigh:
Differential Diagnosis: Commonly trochanteric bursitis, sciatic nerve pain or exacerbations of lumbar spinal stenosis; uncommonly bone or muscle tumors, femur fracture, meralgia paresthetica.
The knee joint:
Differential Diagnosis: Osteoarthritis, chronic meniscal injuries (acute if trauma), pes anserine bursitis, baker’s cysts; uncommonly gout, septic arthritis, flares of rheumatoid arthritis, tibial plateau fracture (if trauma).
The lower leg:
Differential Diagnosis: Commonly pes anserine bursitis (see knee), medial tibial stress syndrome (shin splints), uncommonly stress fracture, tibial or fibular fracture, deep vein thrombosis (DVT), compartment syndrome.
The ankle:
Differential Diagnosis: Commonly ankle sprains (may cause distal tibial, fibular or tib/fib fractures if high impact, or may cause “high ankle” fracture of proximal 1/3 of fibula), osteoarthritis; uncommonly gout (see section on Gout), septic arthritis (see knee).
The foot:
Differential Diagnosis: Commonly osteoarthritis, metatarsalgia (pain syndrome of the metatarsal heads), plantar fasciitis, sesamoiditis, diabetic (or other) neuropathy; uncommonly gout, Mortnon’s neuroma, fracture (esp. Jones’ fracture), distal infarction, ulceration, osteomyelitis (see section on Osteomyelitis).
1. Historical information important in the diagnosis of this problem.
Hip and pelvic pain: (see hip and pelvic pain)
The thigh:
Historical Information: Trochanteric bursitis is classically localized superior and posterior to the greater trochanter, Patients with longstanding spinal stenosis have a wide based gait and tend to lean forward (e.g., on shopping carts, etc). Femur fracture is uncommon except with high impact trauma. Muscle or bone tumors are extremely rare. Meralgia paresthetica is the entrapment of a lateral or anterior cutaneous nerve and is not dangerous, but gives a classic well-circumscribed numbness or burning pain in a circular area on the surface of the skin.
The knee joint:
Historical Information: patients with common osteoarthritis generally have a history of such pain, and new meniscal tears are uncommon in inpatients, unless there is a history of fall or trauma. Position in bed may lead to a flare of a pes anserine bursitis, which is typically localized to the medial aspect of the knee 3-5 cm below the joint line. Patients with RA may develop flares as inpatients. Septic arthritis is uncommon in patients with no history of instrumentation or other cause of bacteremia (even if transient). Gout may be caused in hospitalized patients if thiazide diuretic therapy is initiated.
The lower leg:
Historical Information: New onset posterior pain should be evaluated for DVT. A rapid onset pain out of proportion to the exam should raise suspicion for a compartment syndrome. Medial tibial stress syndrome generally follows sustained activity (e.g., worse after walking).
The ankle:
Historical Information: Sprains usually result from trauma. Osteoarthritis might attack a patient who has been bedbound and is recently walking.
The foot:
Historical Information: Plantar fasciitis may affect patients who have been bed-bound and resume weight bearing. Symptoms are typically worse with the first step out of bed, and then a lancing pain down the plantar surface of the foot from the heel distally with each step. Symptoms of plantar faciitis typically resolve when the patient is non-weight bearing again.
Gout typically affects the MTP of great toe (podagra). Sesamoiditis, caused by inflammation or fracture of the small sesamoid bones on the plantar aspect of the first MTP joint, is generally localized to the plantar surface and only painful with weight bearing.
Pain over the lateral aspect of the foot might indicate a fracture of the base of the 5th metatarsal bone, which is concerning if it affects the vascular supply to the proximal bone hip (named a Jones’ fracture) which may require surgical intervention. Morton’s neuroma (a nerve prolapsing between two metatarsal heads) can present with localized tenderness, generally between, but also above or below the space between two metatarsal heads (most commonly the 3rd and 4th metatarsals).
2. Physical Examination maneuvers that are likely to be useful in diagnosing the cause of this problem.
Hip and pelvic pain: (see hip and pelvic pain)
The thigh:
Physical Exam: Lumbar spinal stenosis typically worsens within seconds when the patient lies down. Trochanteric bursitis causes a lateral leg pain with point tenderness. It should not be affected by hip internal or external rotation.
The knee joint:
Physical Exam: Mild effusions are not uncommon in all causes of knee pain. Septic knees are typically very warm and red, while the normal knee will be slightly colder than the skin around it. Knees with mild to moderate effusions may be slightly warm, but are unlikely to be “hot”. An arthritis knee may have some crepitus, and it is not uncommon for an arthritis knee to have medial joint line tenderness. Meniscal tears will occasionally have a palpable click or cause pain with a meniscal stress testing maneuver (e.g., McMurray’s or Apley’s). The pes anserine bursitis is characteristically point tender over the bursa.
The lower leg:
Physical Exam: Testing active resisted dorsiflexion may reproduce shin splints. Fractures will likely be tender to palpation. A DVT may give a positive Homan’s sign. Later stage compartment syndrome may have the distal foot turn dusky or cold, or have a diminished pulse.
The ankle:
Physical Exam: check active and passive range of motion of the ankle for impediment. Palpation of malleoli may indicate a fracture. If ligamentous disruption from ankle sprain is suspected (more commonly on the lateral aspect of ankle), can check anterior and lateral drawer tests.
The foot:
Physical Exam: Exam indicated plantar fasciitis with the foot in dorsiflexion and deep palpation over the plantar surface of the distal aspect of the calcaneous. Tenderness between 3rd/4th or 2nd/3rd MTPs is common with Morton’s neuroma. Point tenderness over the lateral aspect of the foot may indicate a fracture of the base of the 5th metatarsal. Coldness, color change or splinter hemorrhages under the nail bed, might indicate distal infarction in the foot.
C. Criteria for Diagnosing Each Diagnosis in the Method Above.
Hip and pelvic pain: (see hip and pelvic pain)
The thigh:
Diagnostic Testing: If fracture or tumor is suspected, begin with plain XR and may get MRI if there is high suspicion. If local source of pain is not discovered, consider imaging of the lumbar spine.
The knee joint:
Diagnostic Testing: X-ray a painful knee in the setting of trauma (if looking for tibial plateau fracture, consider CT if X-ray is negative), but an X-ray will be low yield in the setting of pain without trauma, even in the presence of a mild to moderate effusion. In the presence of a moderate to large effusion, consider arthrocentesis (see chapter on arthrocentesis) and send cell count and gram stains. To look for crystals, fluid should be examined in the first 1-3 hours. MRI is the best test for new meniscal or ligamentous injuries, but is rarely necessary in hospitalized patients.
The lower leg:
Diagnostic Testing: Compartment syndrome is a surgical emergency, and should prompt an immediate consultation with orthopedics. Suspected fractures may be worked up with radiographs. Suspected DVT should prompt ultrasound or CT workup.
The ankle:
Diagnostic Testing: Following trauma, the Ottowa ankle rules (test positive if pain near the malleoliand either inability to bear weight both immediately after injury and for four steps on examor bone tenderness at the posterior edge of either mallelous) have 100% sensitivity for malleolar fracture, with radiographs needed only when positive. Suspected osteoarthritis may be supported by weight-bearing ankle films, although these are not necessary for the diagnosis.
The foot:
Diagnostic Testing: Radiographs for fracture of 5th metatarsal, but if radiographs are negative and suspicion is high, consider MRI. MRI is also the study of choice for Morton’s neuroma.
D. Over-utilized or “wasted” diagnostic tests associated with the evaluation of this problem.
See diagnosis.
III. Management while the Diagnostic Process is Proceeding.
A. Management of Clinical Problem Lower Extremity Joint Pain.
In the inpatient setting, once a specific diagnosis is made, management should be tailored to that diagnosis. If the cause of the pain is deemed to be common musculoskeletal pain, it is appropriate to give analgesia (e.g., acetaminophen or non-steroidal pain medications, if the patient can tolerate them). Rarely, narcotic pain medications are needed, although an escalating need for analgesia may trigger further workup. In rare cases of articular pain, intra-articular corticosteroid injection may be used. For tendon and muscle pain, bedside physical therapy may be helpful, but it’s use in arthritis and ligamentous or meniscal pain is limited.
B. Common Pitfalls and Side-Effects of Management of this Clinical Problem.
See individual diagnoses.
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