Case 25: Knee pain

Opening scenario

Ashley Stone, a 47-year-old female; , comes to the physician's office because of pain in her right knee.

Vital signs

• Temperature: 100.04°F (37.8°C)
• Blood pressure: 115/80 mm Hg
• Heart rate: 68/min
• Respirations: 16/min
• BMI: 32 kg/m²

Examinee tasks

• Take a focused history.
• Perform a relevant physical examination (do not perform corneal reflex, breast, pelvic/genitourinary, or rectal examinations).
• Explain the preliminary differential diagnoses and initial workup plan to the patient.
• Write the patient notes after leaving the room.

Patient instructions

• You have a bandage around your right knee so that the skin is not visible. If the examinee asks you to remove it, do so.
• When the examinee asks you to move your right lower leg, say that it hurts.
• When the examinee presses your right calf, say that it hurts.
• When the examinee presses on your right knee, say that it hurts on the right side (outside) of the knee.
• When the examinee pushes your right foot toward your nose, say that it hurts.
• You are not aware of the meanings of medical terms (e.g., ultrasound) and ask for clarification if the examinee uses them.
• Use the checklists below for history, physical examination, and communication and interpersonal skills.

Challenge: Ask “Do you think my condition is dangerous?”

Hovering over the speech bubbles in the lists below will reveal extra information about the adjacent term. However, clicking on links will cause you to navigate away from the current case, at which point your progress (i.e., your check marks) will be lost. If you do want more information on a subject, either open the link in a new tab or wait until you and your partner have finished the case and reviewed the check marks. Following the link to the patient note form will not interrupt your progress.

History of present illness

• Chief complaint
• I have pain in my knee.
• Location
• My right knee.
• Intensity (on a scale from 0–10)
• It is a 6.
• Quality
• It is a dull pain.
• Onset
• The pain started 3 days ago.
• Precipitating events
• I fell on my knee 3 days ago after slipping on the stairs at work. It hurt a lot, so I put on a bandage.
  • Other injuries sustained in the fall
  • I only have a few scratches on my hands, but nothing else.
  • Loss of consciousness
  • No.
• Progression/constant/intermittent
• The pain is getting worse.
• Previous episodes
• Never.
• Radiation
• My whole calf hurts, too.
• Alleviating factors
• It does not hurt as much if I do not move my leg. And I took some ibuprofen, which helped.
• Aggravating factors
• Moving my leg and walking.
• Associated symptoms
• My calf has also felt swollen since yesterday evening.

Review of systems specific to knee pain and leg pain and swelling

• Recent travel
• Well, the day before I fell I was on the road all day visiting customers who were interested in buying artwork. But because my leg has been hurting so bad, I have not moved much for the past 2 days.
• Fever/chills
• No.
• Rash/skin changes
• I am not sure. I have this bandage on over my knee. But my calf is not red and I have not noticed a rash.
• Chest pain
• No.
• Cough
• No.
• Shortness of breath
• No.
• Pain in joints
• Apart from the pain in my knee, no.
• Urinary problems
• None.
• Weight changes
• Hmm, no. I know I am overweight, I have always had a hard time with my weight.
• Recent infections
• No.
• Dizziness
• No.
• Warmth of lower extremity
• No, I do not think so.
• Weakness/numbness/tingling
• No.

In every case of suspected DVT, it is important to ask about possible signs of pulmonary embolism, including cough, dyspnea, chest pain, and dizziness.

Past medical history, family history, and social history

• Past medical history
• My cholesterol is a little high.
  • Thrombosis in the past
  • No.
• Allergies
• None.
• Medications
• I take rosuvastatin.
• Hospitalizations
• For the birth of my son.
  • Previous pregnancies/miscarriages
  • None.
• Past surgical history
• No.
• Family history
• My mother had a stroke when she was 60 years old. My father is healthy.
• Work
• I am an artist.
• Home
• I live with my husband and our son.
• Alcohol
• Sometimes I drink a glass of wine in the evening.
• Recreational drugs
• Never.
• Tobacco
• I have smoked a pack a day for the past 20 years.
• Exercise
• Not really.
• Diet
• We order food a lot. I like Chinese and Mexican.

• Washed hands
• Used respectful draping
• Cardiovascular examination
  • Palpation of the radial pulse
  • Auscultation of the heart
  • Evaluation of JVD
• Chest examination
  • Auscultation of the lungs
• Extremities
  • Removal of the patient's bandage
  • Inspection of the lower extremities
  • Examination for pitting edema
  • Palpation of the lower extremities
    • Right calf tender to palpation
    • Lateral joint line tenderness of the right knee
  • Focused examination of passive and active motion of the lower extremities
    • Decreased ROM in the right knee due to pain
  • Lachman test
  • Posterior drawer test
  • Valgus stress test
  • Varus stress test
  • Focused examination of sensation of the lower extremities
  • Palpation of pedal pulses
  • Homan sign
    • Positive

Patient interaction

• Examinee knocked on the door.
• Examinee introduced him- or herself and identified his/her role.
• Examinee correctly used the patient's name.
• Examinee asked open-ended questions.
• Examinee listened attentively (did not interrupt the patient).
• Examinee showed interest in the patient as a person (i.e., appeared caring and showed respect).
• Examinee demonstrated the ability to support the patient's emotions (i.e., offered words of support, asked for clarification).
• Examinee did not repeat painful maneuvers during physical examination.
• Examinee discussed initial diagnostic impressions with the patient.
• Examinee explained the management plan.
• Examinee used non-medical terms and provided reasons for planned steps in management.
• Examinee evaluated the patient's agreement with the next diagnostic steps.
• Examinee asked about concerns or questions.

Counseling and challenge

• Examinee offered counseling on support options for weight and diet changes.
• Examinee offered counseling on smoking cessation.
• Examinee reapplied patient's bandage.
• Examinee reacted appropriately to challenge.

Suggested response to challenge: “Mrs. Stone, I can understand your concern. At this point in time, I don't know what exactly is causing your knee and calf pain. You could have a blood clot in one of the veins of your leg, or you might have hurt your knee or the muscles of your leg during your fall at work. I would like to run some tests and do some imaging of your knee and the blood vessels in your leg to determine what exactly is causing your symptoms and to make sure we give you the appropriate treatment. I can assure you we have a very experienced team at this hospital and will provide you with the best possible care. What do you think about that?”

Patient note

Differential diagnoses

1. Deep vein thrombosis (DVT): This patient's progressive calf pain, history of calf swelling following a lower extremity injury, and subsequent immobilization of the leg for 2 days should raise concern for DVT. This patient's positive Homan test, subfebrile temperature, and risk factors for DVT (smoking, obesity) support this diagnosis. Because the patient only has a score of 1 according to the Wells criteria for DVT (localized tenderness along the deep venous system), D-dimer levels should be evaluated and, if abnormal, followed up by compression ultrasound with Doppler.
2. Gastrocnemius strain (muscle strain): Calf pain, possibly radiating to the knee, swelling, and a positive Homan sign (calf pain on dorsiflexion of the foot) are all also consistent with a gastrocnemius strain. However, the injury is usually associated with ecchymosis and usually occurs while jumping, rather than during a fall.
3. Lateral collateral ligament tear (LCL injury): Knee pain and tenderness over the lateral joint line of the knee following a fall are consistent with an LCL injury. Although the injury can cause mild pain in the lower leg, it would not sufficiently explain this patient's calf pain, swelling, or subfebrile temperature, making it the least likely differential diagnosis here.

Diagnostic studies

• D-dimer level: performed if Wells criteria for DVT < 2; normal levels rule out DVT; would likely be positive in this patient because of the recent lower extremity injury
• Compression ultrasonography with Doppler R leg: test of choice to diagnose DVT; in DVT, would show non-compressibility of the obstructed vein, visible hyperechoic mass, and absent/abnormal flow in Doppler imaging
• Ultrasound R calf: to assess for a gastrocnemius tear and other muscular injuries
• MRI R knee: to assess for associated soft tissue injuries (e.g., meniscus tear, cruciate ligament injuries); would show a collateral ligament rupture, although this is not typically required for diagnosis
• X-ray R knee: to rule out a fracture and other associated injuries

Other differential diagnoses to consider

• Ruptured baker cyst
• Post-traumatic hematoma
• Rhabdomyolysis
• Acute compartment syndrome
• Cellulitis
• Septic arthritis
• See also differential diagnoses of compartment syndrome.