Discussion
Examiner: Summarize your case and give a differential
"Mr. David Johnson is a 50-year-old former football player with a background history of Diabetes mellitus on Metformin, who presents with 4 months of right knee pain. The pain is gradual in onset, dull and aching, worsens with activity and at the end of the day, and improves with rest. He reports morning stiffness of about 10 minutes. He had a knee injury and surgery 30 years ago, details of which are unclear. There are no associated swelling, redness, systemic symptoms, or other joint involvement."
The most likely diagnosis is post-traumatic osteoarthritis on the account of his past knee injury, his pain also being in keeping with the differentiating and exacerbating include:
Chronic meniscal tear.
Inflammatory arthritis such as ankylosing spondylitis or rheumatoid arthritis.
Primary or secondary bone malignancy.
Osteonecrosis of the knee.
Crystal arthropathy including gout and pseudogout.
Septic arthritis, which is unlikely.
Give your main diagnosis, and then list the others, try to make a list from the most likely to the less likely.
Examiner: What is your management plan?
I would first examine the patient, and inform my seniors to get their advice, this will allow me to order a more focused set of investigations, but investigations needed may include:
Biochemical investigations:
FBC: Looking for anemia, which is seen with malignancy, chronic disease, and inflammatory bowel disease, leukocytosis, which is seen with infective or inflammatory pathologies.
CRP and ESR: As inflammatory markers.
Serology: looking for autoimmune process is suspected such as rheumatoid arthritis.
Imaging:
X-ray of the knee in two views looking for signs of osteoarthritis.
MRI scan of the knee which can better characterize osteoarthritis, detect early changes, and detect meniscal or ligamentous injuries.
Examiner: How would you treat this case?
After discussion with my seniors, treatment will be tailored to the underlying diagnosis, in this case osteoarthritis is most likely, treatment options can include:
Conservative treatment:
Achieve healthy weight and maintain exercise, this will reduce mechanical stress on the joint.
Physiotherapy, focusing on strengthening the muscles around the knee.
Analgesia, this may include paracetamol or NSAID's.
Intra-articular steroid injections.
Surgical management:
Total or partial arthroplasty.
Arthroscopy, in conclusion if there are loose bodies or meniscal tears, but it does not affect the progression of osteoarthritis.
Realignment osteotomies, which are designed to redistribute weight away from the affected knee compartment, it can delay the need for arthoplasty.
Examiner: If total knee replacement is carried out, what are the causes failure of total knee replacement?
Aseptic loosening of the implant.
Wear and tear in the joint.
Early or late prosthetic joint infection.
Periprosthetic fractures.
Examiner: What do you mean by aseptic loosening?
Aseptic loosening refers to the separation of the implant from the bone due to chronic inflammatory reaction, it does not involve bacterial infection, rather the debris from the wearing of implant components triggers an inflammatory reaction in the surrounding bone, leading to osteolysis, bone loss and implant loosening over time, it is a long term complication.
Examiner: Will this patient be able to play soccer in 9 months after a total knee replacement, and why?
Unlikely to be able to play soccer in 9 months, it is generally not recommended because this can damage the prosthesis and cause early loosening of the implant.
Examiner: What X ray findings are consistent with osteoarthritis?
Joint Space Narrowing (JSN)
