Case 4

Patient basic data: Thomas T, male, dob 01.01.1994, (26 y/o), smoking, no treated hypertension, or diabetes.

Symptom: Swollen knee

Fictional diagnosis: ACL rupture with chronic instability

History: The patient is an amateur soccer player. He does not engage in other sports, and besides soccer, he does not regularly run. Instead he primarily engages in resistance training of the upper body. About 5 months ago, he sustained a knee distortion trauma with pain during a soccer match shortly before the end of the season leading into the winter break. At that time, he also had swelling with pain in the knee, which improved after a few days of rest and sympathetic relief. He did not consult with a doctor, because the pain and swelling improved quickly. Having a good muscle status, he had no further complaints. For about 3 months, during winter break, he had paused playing soccer anyways and had not done any substitute running. He had no problems with his gait and was fine during his desk job and during leisure time. Only when he went down the stairs, he felt a slight instability in his knee and therefore preferred to hold on to the railing. But there were no real events of pain. Now, after resuming soccer, he sensed some instability during every weekend game, combined with pain in the knee joint (VAS 4–5), and swelling, which decreases after 3–4 days. After 5 days of symptomatic rest and almost no complaints, he talked with his friends about this annoying occurrence and how he was not sure of the cause. They suggested he use the app for getting some helpful information.

Examination results: Normal gait, Zohlen sign negative, low effusion, no patella embracing pain, no overheating/redness, no pain on palpation over medial/lateral knee joint gap, the popliteal fossa or the tibial head, meniscus signs negative. Lachman test, anterior drawer test, pivot shift test positive; free ROM, peripheral circulation, motor function and sensitivity intact, thigh circumference (20 cm above the knee cap) ipsilateral reduced by 1 cm

Not anticipated while creating the vignette (and filled in while using the app in this trial): No morning stiffness, no lumps under the skin behind the knee or over a joint, no shin pain, no calf pain

Answers suspected not to be answered by the fictional patient: N/A

Number of symptom-related questions: 30

General app estimation (“next steps”): People with symptoms similar to yours may require emergency care. If you think this is an emergency you should go to an emergency department without delay.

Suggested diagnoses: 1. Knee bursitis (seek medical advice): 3 out of 10 people with these symptoms had this condition. 2. Anterior cruciate ligament injury (seek emergency care): 1 in 10 people with these symptoms had this condition. 3. Patellar tendinitis (can usually be managed at home): 8 out of 100 people with these symptoms had this condition. 4. Popliteal cyst (seek medical advice): 7 out of 100 people with these symptoms had this condition. 5. Tractus iliotibialis syndrome (can usually be managed at home): 4 out of 100 people with these symptoms had this condition.

Note: The patient would have found it difficult to answer many of the questions because the symptoms questioned were no longer present at the time of the examination.