CME INDIA Presentation by Dr. Ashu Rastogi, MD, DM(Endocrinology), FACE, FRCP (Edin), Faculty, Dept. Of Endocrinology, PGIMER, Chandigarh, India.

Based on a presentation at Diabetica, RSSDI-Gujrat, Ahmedabad on 20-05-2023.

What could be the possible etiology?

Addressing the pathophysiology of Charcot

53-yr-old gentleman, type-2 diabetes for 9 years came with swelling of right foot for 12 weeks.

What is the possible diagnosis?

1. Cellulitis.
2. Osteomyelitis.
3. Gouty arthritis.
4. Charcot’s foot.
5. Traumatic fracture.

Is it Vanishing Bone Disease?

Outcome

Another case

• 43-yr-old lady.
• T2DM for 6 yrs., on OADs.
• Swelling and progressive deformity of left foot for 1 year.
• History of swelling and redness of same foot 1 year prior.
• Had been treated with varying course of antibiotics.

Mid-foot involvement Sequelae of Charcot foot.

Pes planus.

Here is Concurrent Wrist and Mid foot Charcot Neuroarthropathy

Why Imaging is required?

• Active Charcot is essentially a Clinical Diagnosis.

Temperature difference between feet (>2C) is sine-quo-non

• Varied presentation.
• Non-specific symptoms.
• Clinically Innocuous and Surprise on radiograph.
• Common Differentials:
  • Cellulitis.
  • Gout.
  • Deep Vein Thrombosis.
  • Tubercular Rheumatism.
  • Osteomyelitis.

Imaging: Conventional Radiography

• Bilateral Foot Radiograph Weight Bearing.
• Views:
  • Dorsoplantar.
  • Lateral.
  • Pronated oblique views.

• Can be normal in early stages
• Anatomical classifications:
  • Eichenholtz (Fragmentation, Coalescence, Reconstruction).
  • Sanders & Frykberg (5 types).
  • Brodsky (5 types).

Anatomical classification

Plane Radiography

Acute CN:

• Flattening of the metatarsal head is 1st sign.
• Also, early finding is focal demineralization.
• Strong indicators of neuroarthropathy on radiograph:
  • Absence of soft tissue involvement.
  • Polyarticular distribution.
  • Subchondral or periarticular changes in the midfoot.
  • Involvement of the IP joints and ankle less common.

• Chronic CN: Rule of ‘‘6 D’s’’
  • Distension of joints.
  • Destruction.
  • Dislocation.
  • Disorganization.
  • Debris.
  • Density increase (sclerosis).
• Midfoot or tarsometatarsal (Lisfranc) typically affected.
• Collapse of the longitudinal arch.
• Increased load on cuboid, causing a rocker bottom deformity.

Limitations of Plane Radiographs

• Subtle changes such as occult fractures, bone marrow oedema not detected.
• Low sensitivity and specificity rates (< 50%) in detection of early findings of CN.
• May be normal in early CN.

Do all patients require MRI scan?

• If Plain X-ray is normal and strong suspicion of active Charcot.
• Overlying ulcer for better soft tissue details.
• Differentiate DFO with Charcot.
• Follow-up for remission.

MRI Characteristics

• Acute CN:
  • Soft tissue edema.
  • Joint effusions.
  • Subchondral bone marrow edema.
  • Disruption of Lisfranc ligament.
  • Malalignment and collapse of the longitudinal arch.
  • Bone marrow edema: Low signal intensity on T1W and high signal intensity on T2W images.

• Bone-marrow enhancement predominantly in the subchondral region on Gd -enhanced studies.

When do we need nuclear scans?

Not Required Routinely

• Skin is ulcerated as a result of Charcot deformity.
• Secondary osteomyelitis is a possible complication.
• Follow-up for quiescence of Active CN.
• What kind of nuclear scan are useful?
  • Tc99m-MDP three phase bone scans.
  • WBC labelled bone scan.
  • F18 PET/CT.
  • F18 WBC- PET/CT.
  • Labelled WBC scan to differentiate DFO and CN.

What to inform the radiologist?

• Use a fluid sensitive sequence (e.g., STIR) for assessing edema in the bone marrow and soft tissue.
• A classic T1 TSE (turbo spin-echo) sequence for:
  • Anatomy.
  • Fat signal of the bone marrow.
• T2-weighted sequences can demonstrate:
  • Subchondral cysts.
  • Fluid collections.
  • Sinus tracts.

How to Stop Acute Charcot?

How to recognize remission in active CN?

How long to continue offloading with TCC?

• Till remission of active phase of Charcot.
• Shift the patient from non-walking TCC to CROW boot or modified footwear.

How to recognize remission?

• Temperature difference between two foot is <2⁰C for 4 weeks.
  • Other markers.
  • Bone turnover markers.
  • MRI signal intensity changes.
  • PET CT SUV.

What happens after remission of Charcot?

Effect on BMD as per Sinacore DR et al. Phys Ther 2008

• BMD was 13% greater in controls than diabetes with neuropathy.
• BMD was 16% lower in the charcot foot.

Survival in People with Charcot Foot

• (Chaudhary S, Rastogi A. Acta Diabetologica 2019)
  • 15.0% with CN and 9.8% (p=0.03) individuals without CN died.
  • Mean survival in CN was 4.49 years compared to 4.78 years (p<0.01) without CN.
  • Unadjusted OR=1.62 (CI, 1.03-2.5; p=0.03).
  • Adjusted OR=2.72 (CI, 1.4-5.2; p=0.003).
• CN is associated with a higher mortality compared to people with diabetes without CN.
• Despite being younger, CN patients have a higher prevalence of microvascular complications.

Other Considerations

• Teriparatide increases foot bone remodelling by an osteoanabolic action in people with CN.
• Data are too weak to support the use of bisphosphonates as a routine treatment for acute Charcot neuroarthropathy.

Quick Take-Aways

• Offloading is the gold standard strategy that could arrest the progression of deformity.
• Data are too weak to support the use of bisphosphonates as a routine treatment for acute Charcot neuroarthropathy.

CME INDIA Learning Points (By Dr. Ashu Rastogi)

• Charcot Foot is essentially a clinical diagnosis.
• Radiology supports the diagnosis when strong index of suspicion.
• Plane radiograph may be normal in acute CN.
  • Anatomical classification
• MRI useful for:
  • Early detection of acute CN.
  • Better soft tissue details.
  • Differentiating osteomyelitis.
  • Follow up for Quiescence.
• PET scan (Limited Role):
  • Differentiate OM in complicated cases.
  • Better marker of remission.

CME INDIA Tail-Piece

• The Charcot foot has been first described in 1868 by Jean-Martin Charcot.
• His early investigations into the tabetic arthropathies (1868) led to brilliant presentation, Demonstration of Arthropathic Affections of Locomotor Ataxy, at the 7th International Medical Congress (1881).
• He established this disease as a distinct pathological entity.
• Charcot and Féré published the first observations of the tabetic foot (Pied tabétique) in the Archives de Neurologie in 1883.
• It was not until 1936, however, that W. R. Jordan established the association between neurogenic arthropathy of the foot/ankle and diabetes mellitus.
• The detailed pathomechanisms of this disease still remain unclear.
• It is said that the cause is multifactorial and that polyneuropathy (reduced pain sensation and proprioception) is the underlying basic condition of this disease.
• Diabetes mellitus is the main cause of polyneuropathy in the lower limb much more common than other causes like alcohol abuse or malnutrition.

References:

1. Vanishing Bone Disease.Rastogi A, Bhansali A.Post Graduate Med Journal 2016; doi: 10.1136/postgradmedj-2016-134183
2. Rastogi, Ashu & Prakash, Mahesh & Bhansali, Anil. (2018). Varied presentations and outcomes of Charcot neuroarthropathy in patients with diabetes mellitus. International Journal of Diabetes in Developing Countries. 39. 10.1007/s13410-018-0700-8.
3. Rastogi A, Hajela A, Prakash M, Khandelwal N, Kumar R, Bhattacharya A, Mittal BR, Bhansali A, Armstrong DG. Teriparatide (recombinant human parathyroid hormone [1-34]) increases foot bone remodeling in diabetic chronic Charcot neuroarthropathy: a randomized double-blind placebo-controlled study. J Diabetes. 2019 Sep;11(9):703-710. doi: 10.1111/1753-0407.12902. Epub 2019 Feb 13. PMID: 30632290.
4. Sanders LJ. The Charcot foot: historical perspective 1827-2003. Diabetes Metab Res Rev. 2004 May-Jun;20 Suppl 1:S4-8. doi: 10.1002/dmrr.451. PMID: 15150805.
5. Rosskopf, A.B., Loupatatzis, C., Pfirrmann, C.W.A. et al. The Charcot foot: a pictorial review. Insights Imaging 10, 77 (2019). https://doi.org/10.1186/s13244-019-0768-9

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