I'm 33 yrs old doctor with no comorbidoties c/o pain in the medial side of second proximal metatarso pharyngeal joint. With signs of inflammation. Looks like sinovitis. Esr, uric acid, crp are normal. What maybe the cause
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second metatarsophalangeal joint synovitis causes
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I now have a thorough picture. Here is a comprehensive, evidence-based answer:
Pain and Synovitis at the Second MTP Joint - Normal ESR/CRP/Uric Acid
This is a classic and well-described clinical scenario. The second MTP joint is the most common site for synovitis, instability, and fixed deformity among the lesser toes - and with normal inflammatory markers, several non-inflammatory and seronegative causes jump to the top of the list.
Most Likely Causes (in order of probability for your presentation)
1. Plantar Plate Tear / MTP Joint Instability (Most Common)
This is the most likely diagnosis in an active, otherwise healthy person.
The plantar plate is a fibrocartilaginous structure that provides most of the stabilizing force at the lesser MTP joints. It originates from the metatarsal metaphysis and inserts firmly onto the base of the proximal phalanx. Chronic overload, high-heeled footwear, or a relatively long second metatarsal causes attritional degeneration and eventual rupture, producing:
- Synovitis and joint effusion (early stage)
- Medial deviation of the second toe (explains the medial-side pain)
- Insidious onset of metatarsalgia worsened with high heels
The second toe has two dorsal interossei and no plantar interosseus, making it biomechanically unique and especially vulnerable to medial deviation once the plantar plate and accessory collateral ligament fail.
Key exam findings: Lachman/drawer test (dorsal translation of proximal phalanx on metatarsal) and paper pull-out test (assesses flexor strength/toe purchase). A positive drawer combined with deviation toward the third toe strongly suggests a high-grade plantar plate tear.
Staging (Coughlin classification):
| Stage | Finding |
|---|---|
| 0 | Pain, swelling only - normal alignment, negative drawer |
| 1 | Mild medial deviation, mildly positive drawer (<50% subluxation) |
| 2 | Moderate deformity, no toe purchase, >50% subluxation |
| 3 | Dorsal dislocation/crossover toe |
Your patient sounds like Stage 0-1 - the inflammatory-looking swelling is the synovitis that precedes structural failure. Campbell's Operative Orthopaedics 15th Ed 2026, p.4927-4929
2. Freiberg's Infraction (Avascular Necrosis of the Metatarsal Head)
- Osteonecrosis of the second (most common) or third metatarsal head
- Typically in adolescents/young adults (age 13-18 most common, but can occur in 30s)
- Presents with metatarsalgia, swelling, limited MTP range of motion
- X-rays may be normal early; MRI is the gold standard
- ESR/CRP are normal
- Miller's Review of Orthopaedics 9th Ed lists it as a classic osteonecrosis of the metatarsal head
3. Seronegative Spondyloarthropathy (Psoriatic Arthritis / Reactive Arthritis)
Even with normal CRP/ESR, early or oligoarticular psoriatic arthritis can present this way:
- Asymmetric oligoarticular pattern is typical at onset
- Dactylitis or enthesitis may be subtle early on
- No skin findings are required - psoriasis may precede joint disease by years or appear after
- HLA-B27 and seronegative - so ESR/CRP can be normal, especially early
- Reactive arthritis (post-infectious) can produce a monoarticular foot synovitis
Ask specifically about: any psoriatic skin/nail changes, prior GI/GU infection (reactive arthritis), morning stiffness, back pain, eye redness.
4. Mechanical/Biomechanical Causes
- Morton's foot (long second metatarsal relative to first) - increases load on second MTP
- Interdigital (Morton's) neuroma - usually in 2nd/3rd web space, neuritic rather than articular, but can coexist
- Hammer toe deformity - produces MTP hyperextension and chronic synovitis
- Footwear-related overload (narrow toe box, high heels, long-distance running)
5. Early Rheumatoid Arthritis (Less Likely But Must Not Miss)
- The second and third MTP joints are classic early RA sites
- CRP/ESR can be normal in early or seronegative RA (15-20% of RA is seronegative)
- Check: anti-CCP antibody (positive in ~70% of RA, often before RF turns positive) and RF
- Morning stiffness > 30-45 minutes is a key symptom
6. Stress Reaction / Stress Fracture
- Particularly in active individuals or runners
- Second metatarsal is the most common stress fracture site in the foot
- X-ray often normal early; bone scan or MRI will show it
- Produces focal bone pain, swelling, inflammation signs
Suggested Workup
| Test | Purpose |
|---|---|
| Anti-CCP, RF | Rule out seronegative/early RA |
| HLA-B27 | Spondyloarthropathy workup |
| MRI foot (gold standard) | Plantar plate integrity, Freiberg's, stress reaction, synovitis grade |
| Ultrasound (MSK) | Dynamic assessment of plantar plate, effusion, tenosynovitis |
| Weight-bearing X-ray | Metatarsal length (Morton's index), bony erosions, early Freiberg's sclerosis |
| Drawer/Lachman test | Clinical confirmation of plantar plate instability |
| Skin/nail exam | Psoriatic changes |
| Urine/GU history | Reactive arthritis trigger |
Bottom Line
In a 33-year-old with no comorbidities, normal uric acid, ESR, and CRP, the most probable cause of second MTP joint synovitis with medial-side pain is plantar plate tear/insufficiency (Stage 0-1 MTP instability), followed by Freiberg's infraction and early seronegative spondyloarthropathy. An MRI of the forefoot will distinguish these efficiently, and a detailed MSK exam (drawer test, paper pull-out test) should be done first.
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