Use Case Title: Allergy to Nickel in Knee Implant – Misattribution of Allergy
1. Use Case Description
The purpose of this use case is to describe a misattribution of an adverse event to
a nickel allergy. The adverse event was reported by the health professional to the device
manufacturer who then sent the report to the FDA.
3. Conditions
This use case is an example of an adverse event that can occur due to a reaction to
an implanted medical device. Patients may have allergies to medical devices that are
previously unknown to the patient and health care professionals.
4. Exclusions
There are no exclusions associated with this use case. The patient was presumed
to not be on any immunosuppressant medications at the time of the event.
5. Preconditions
The patient had undergone a partial knee arthroplasty in 2011.
6. Use Case Sequence of Steps
 Prior to surgery, surgeon worked up patient for partial knee arthroplasty.
 No known allergies at time of workup including no known allergies to metals or
jewelry.
 Patient had a partial knee arthroplasty; the RESTORIS Multicompartmental Knee
System was implanted.
 Patient returned to the surgeon for a post-operative appointment seven months
after surgery.
 Patient complained of joint pain and a swollen knee.
 Surgeon observed knee was filled with blood.
 Surgeon drained the knee and ordered test and x-rays. The tests were negative for
infection and the x-rays did not show implant misalignment.
 Surgeon converted the partial knee to a total knee procedure using a Smith &
Nephew OXONIUM Total Knee System.
 Surgeon noted no loosening of the implant components during procedure. The
patient’s synovium, however, was bloodstained.
 Surgeon concluded that this was an adverse reaction to the nickel in the implant.
 Surgeon reported event to manufacturer.
7. Post Condition
 Manufacturer of RESTORIS Multicompartmental Knee System conducted an
evaluation of the event as part of their complaint follow-up process.
 Patient EHR updated with new nickel allergy/intolerance
8. Use Case Scenario
A patient underwent a partial knee arthroplasty and later reported joint pain and a
swollen knee. The patient’s implant was removed and replaced by a different total knee
system.
Medical History:
 Prior to surgery, had a pre-operative appointment.
 Not reported, but should include any known history of allergy or intolerances
to metals, as well as other medications or substances.
 It may also be helpful to include a history of previous surgeries, especially if
the patient has received any prior medical device implants.
Initial Surgery:
 Patient underwent partial knee arthroplasty.
Presenting Complaints Post-Operative:
 Swollen knee
 Joint pain
Post-Operative Examination:
 Surgeon noted that the knee was filled with blood and consequently drained
the knee.
 Tests for infection negative.
 X-rays did not show any signs of implant alignment problems.
Diagnosis:
 Surgeon concluded the patient has a nickel allergy. This was a misattribution
as the patient probably did not have an allergic reaction to nickel but rather a
dermatitis reaction due to the presence of the metal.
Treatment:
 The RESTORIS Multicompartmental Knee System was removed and replaced
by a Smith & Nephew OXONIUM Total Knee System.
Outcomes:
 Patient has a Smith & Nephew OXONIUM Total Knee System.
 The patient’s allergy/intolerance list updated to reflect misattributed nickel
allergy.
 A dermatology consult is ordered by the health care team and results in the
ordering of a patch test. It is noted that no nickel allergy is present and the
dermatologist amends the allergy list so that the nickel allergy entry is now
inactive. Note that the item is purposefully not removed from the list to allow
for future reference.
*Note: Information was added to this use case for the purpose of this exercise.