I have enough from the textbooks now. Let me give you a thorough, honest answer.
Honest breakdown of your situation
First, let me be clear: I'm not your doctor and nothing here replaces face-to-face care. But I can help you understand what's happening and what questions to ask.
What your MRI actually found - two separate things
1. Medial meniscus tear
The medial (inner side) meniscus is a crescent-shaped cartilage cushion. A tear in it causes exactly what you have: medial joint line pain, swelling (effusion), and tenderness. This is the more pressing, symptomatic finding.
2. Discoid lateral meniscus ("discoid morphology")
This is a congenital variation - your lateral (outer) meniscus never developed the normal crescent shape and stayed disc-shaped instead. This is found in about 0.4-5% of people and is often discovered incidentally. Importantly:
- If it's intact and not torn, it may require no treatment at all
- Per Campbell's Operative Orthopaedics (15th Ed 2026): "The abnormality accounting for the symptoms should be appropriately corrected, and the discoid lateral meniscus should be left intact unless torn or degenerative"
- You have been living with this your whole life - it is likely NOT what's causing your current acute pain
So the acute picture - sudden pain + swelling + fever + no injury = is mostly the medial meniscus tear with joint effusion.
The fever - this matters
You mentioned fever early on. Fever with a swollen joint in a young person is something doctors take seriously because it could indicate:
- Reactive arthritis - your immune system overreacting, sometimes triggered by a prior infection (gut, urinary, or respiratory)
- Septic arthritis - infection inside the joint (this is an emergency, but your ortho examining you and NOT rushing you to hospital suggests this was ruled out clinically)
- Crystal arthropathy (gout/pseudogout - less common at 22 but possible)
- The fever could also have been coincidental (a viral illness alongside a pre-existing torn meniscus finally becoming symptomatic)
The fact that no doctor has expressed urgency about the fever is reassuring, but it's worth explicitly asking your second doctor: "Was the fever investigated? Was any blood work done for inflammatory markers (CRP, ESR, uric acid, CBC)?"
Should you get the arthroscopy the first doctor recommended?
This is the big question. Here's the honest picture:
What arthroscopy can do:
- Directly visualize and trim or repair a torn meniscus
- Address the discoid lateral meniscus if it's also problematic
- Relieve effusion and pain faster
What the evidence says about rushing to surgery:
- For isolated meniscal tears without mechanical locking (the knee getting "stuck" mid-motion), conservative treatment - rest, anti-inflammatories, physiotherapy - is a reasonable first step, especially in young patients
- Campbell's notes that "preexisting degenerative changes, female gender, and age older than 20 years are associated with unsatisfactory results" for partial meniscectomy in discoid meniscus cases - this means surgery is not automatically better just because it's faster
- However, if there is a large tear causing persistent effusion and pain that does not settle, surgery is often needed
Bottom line on surgery: Your second doctor's 10-day conservative trial is reasonable and standard. The issue is you're only 5 days in and pain is increasing. That warrants going back now, not waiting 5 more days.
What the "knee injections" likely are
The second doctor almost certainly means one of two things:
- Corticosteroid injection (methylprednisolone or triamcinolone) - reduces inflammation rapidly, very effective for effusion and pain
- Hyaluronic acid (viscosupplementation) - less likely given your acute presentation
Either way, these are standard and appropriate. You should ask him to name them.
My honest advice - here's what I would do in your position:
1. Do NOT wait 5 more days if pain is worsening. Call your second doctor now and tell him the pain has increased over 5 days rather than improved. This changes the clinical picture and he may want to see you sooner, do blood work, or bring forward the injections.
2. Ask for blood tests if not already done:
- CBC (complete blood count)
- CRP and ESR (inflammation markers)
- Uric acid
- These help rule out infectious/inflammatory causes that might explain the fever
3. Ask the second doctor specifically:
- "What are the injections you plan to give me, and what do they do?"
- "Was the fever I had consistent with the knee problem, or could it be from something else?"
- "At what point do you recommend surgery, and what would change your mind?"
4. On the surgery question: Don't let either doctor rush you into arthroscopy, but also don't fear it unnecessarily. If conservative treatment genuinely fails over 4-6 weeks, arthroscopy for a symptomatic medial meniscus tear in a 22-year-old is a routine, generally safe procedure with good outcomes. The discoid lateral meniscus does NOT need to be removed unless it is itself torn or causing problems.
5. Your instinct that the pain is real is correct. A medial meniscal tear with effusion is genuinely painful. You are not overthinking it.
Red flags - go to emergency if you develop:
- High fever returning (>38.5°C)
- Knee becomes red, very hot to touch, and you cannot move it at all
- Severe sudden worsening of pain
These could indicate the rare but serious septic arthritis that needs urgent drainage.
The short version: your MRI explains your pain, the discoid meniscus is likely a bystander finding, conservative treatment is reasonable but only if it's actually working - and since it isn't after 5 days, contact your doctor today, not in 5 more days.