Patient: 38-year-old man with Type 1 diabetes mellitus Presentation: Progressive right knee swelling and deformity over 3 months, minimal pain despite severe clinical appearance, low-grade fevers Relevant history: Type 1 DM for 25 years, very poor compliance (HbA1c 12%), previous tibial plateau fracture 5 years ago (ORIF), known peripheral neuropathy, visual impairment from retinopathy, no previous ulceration Examination findings:
| Test | Result | Normal Range | Interpretation |
|---|---|---|---|
| BSL | 47 mmol/L | 4-8 mmol/L | ↑↑↑ Severe hyperglycaemia |
| HbA1c | 12% | <7% | ↑↑ Very poor diabetic control |
| WCC | 18.5 ×10⁹/L | 4-11 ×10⁹/L | ↑ Leucocytosis |
| CRP | 185 mg/L | <5 mg/L | ↑↑ Markedly elevated |
| ESR | 95 mm/hr | <15 mm/hr | ↑↑ Elevated |
| Creatinine | 145 μmol/L | 60-110 μmol/L | ↑ Diabetic nephropathy |
| Hb | 98 g/L | 130-170 g/L | ↓ Anaemia of chronic disease |
| Albumin | 25 g/L | 35-50 g/L | ↓ Poor nutrition/chronic illness |
Image 1: AP and Lateral Radiographs of Right Knee
Radiological features:
Image 2: MRI Right Knee
MRI findings:
Image 3: Labelled WBC Nuclear Scan
Findings:
What is your interpretation of the clinical and investigation findings?
What is the Eichenholtz classification and why is it relevant?
What is your immediate management plan?
The patient is medically stabilised. Cultures grow MRSA. What are the surgical options?
If you proceed with arthrodesis, describe your surgical approach.
What factors would you discuss when counselling this patient?
This pattern suggests Infected Charcot Arthropathy:
Distinguish Charcot from Septic Arthritis:
| Feature | Charcot | Septic Arthritis |
|---|---|---|
| Pain | Minimal (neuropathic) | Severe |
| Destruction | Progressive over weeks-months | Acute destruction |
| Systemic | May have low-grade inflammation | Usually febrile, unwell |
| WBC scan | Negative (unless infected) | Positive |
Key Point: BSL 47 mmol/L is a medical emergency requiring immediate treatment before any orthopaedic intervention.
Q: "Why would you MRI the spine in unilateral Charcot?"
Unilateral Charcot is unusual - bilateral expected with diabetic peripheral neuropathy. Unilateral involvement suggests:
Q: "What is the difference between Charcot and osteomyelitis on imaging?"
| Feature | Charcot | Osteomyelitis |
|---|---|---|
| Bone scan | Positive | Positive |
| Labelled WBC scan | Negative | Positive |
| MRI marrow oedema | Present | Present |
| Cortical destruction | Subchondral | May be focal |
| Soft tissue abscess | Absent | May be present |
Key: WBC-labelled scan helps differentiate - negative in pure Charcot, positive in infection.
Q: "What are the risk factors for wound complications after surgery in diabetics?"
| Risk Factor | Impact |
|---|---|
| HbA1c >8% | Increased infection, poor healing |
| Albumin <30 g/L | Poor wound healing |
| Peripheral arterial disease | Ischaemia |
| Smoking | Vasoconstriction, poor healing |
| Neuropathy | Unrecognised trauma |
| Immunosuppression | Infection risk |