What is the diagnosis and treatment for fingers and toes deteriorating with the big toe bending upward, possibly indicating a condition such as rheumatoid arthritis (RA) or diabetic neuropathy?

Diagnosis: Charcot Neuro-Osteoarthropathy (Charcot Foot)

The clinical presentation of deteriorating fingers and toes with the big toe bending upward in a patient with diabetes strongly suggests active Charcot neuro-osteoarthropathy (CNO), and immediate knee-high immobilization/offloading must be initiated while diagnostic imaging is obtained to prevent irreversible deformity. 1

Clinical Recognition

Always consider active CNO when a patient with diabetes and neuropathy presents with:

• Increased temperature in the foot compared to the contralateral side 1
• Edema and/or redness of the foot with intact skin 1
• Foot deformities including the big toe bending upward (which may indicate joint malalignment or subluxation) 1

The "deteriorating" fingers and toes likely represents progressive bone and joint destruction characteristic of CNO, while the upward bending of the big toe suggests dorsal subluxation or dislocation at the metatarsophalangeal joint. 1

Immediate Management Algorithm

Step 1: Clinical Assessment

• Perform comprehensive foot examination assessing for loss of protective sensation using 10-g monofilament testing plus at least one other neurological assessment (pinprick, temperature, ankle reflexes, or 128-Hz tuning fork) 1
• Assess for peripheral arterial disease by examining lower-extremity pulses, capillary refill time, rubor on dependency, and pallor on elevation 1
• Evaluate for foot deformities including bunions, hammertoes, and prominent metatarsals 1

Step 2: Temperature Assessment

• Use infrared thermometry to measure skin temperature bilaterally, calculating the temperature difference between the affected foot and the same anatomic point on the contralateral extremity 1
• A temperature difference supports the diagnosis of active CNO 1

Step 3: Immediate Immobilization

Initiate knee-high immobilization/offloading immediately upon suspicion of active CNO, even before imaging confirmation. 1 This is a strong recommendation despite low-quality evidence because withholding offloading therapy puts the patient at unnecessary risk of dire consequences including permanent deformity. 1

Diagnostic Imaging Protocol

Initial Imaging

1. Obtain bilateral weight-bearing plain X-rays of the foot and ankle including anteroposterior (AP), medial oblique, and lateral projections for the foot, plus AP, mortise, and lateral projections for the ankle 1
2. Weight-bearing radiographs are preferred as they detect dynamic abnormalities including joint malalignment, joint subluxation, and fracture displacement that may not be apparent on non-weight-bearing films 1

Advanced Imaging

• If plain X-rays appear normal but clinical suspicion remains high, perform MRI to diagnose or exclude active CNO (Strong recommendation; Moderate certainty) 1
• If MRI is unavailable or contraindicated, consider nuclear imaging (scintigraphy), CT scan, or SPECT-CT (Conditional recommendation; Low certainty) 1

What NOT to Use

• Do not rely on C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood count, or alkaline phosphatase to diagnose or exclude CNO 1

Differential Considerations

Rheumatoid Arthritis Connection

While the patient may have rheumatoid arthritis, Charcot arthropathy can occur in patients with RA-associated peripheral neuropathy. 2 In a case series, 52% of Charcot feet in RA patients had no other known sources for neuropathy besides RA itself. 2 Peripheral neuropathy occurs in approximately 75% of RA patients, though only 21% have clinical sensory loss on examination. 3

Diabetic Neuropathy

Diabetic peripheral neuropathy remains the most common cause of Charcot arthropathy. 2 The combination of diabetes and neuropathy significantly increases risk for CNO development. 1

Treatment Protocol

Offloading Strategy

1. Use a total contact cast or non-removable knee-high walker boot as first-line treatment (Strong recommendation; Moderate certainty) 1
2. If knee-high devices are contraindicated or not tolerated, consider a removable knee-high walker boot (Conditional; Low) 1
3. Do NOT use below-ankle devices (surgical shoes, postoperative sandals, custom molded shoes) due to inadequate immobilization and limited offloading capacity 1
4. Use assistive devices (crutches, walker) to reduce weight-bearing on the affected limb 1

Pharmacologic Management

• Do NOT use bisphosphonates (alendronate, pamidronate, zoledronate), calcitonin, PTH, methylprednisolone, or denosumab for active CNO treatment (Strong recommendation; Moderate certainty) 1
• Consider vitamin D and calcium supplementation during fracture healing according to national guidelines for those at risk of deficiency 1

Surgical Consideration

Consider surgical intervention if there is: 1

• Instability of foot and ankle joints
• Deformity with high risk of ulcer development in the offloading device
• Pain that cannot be sufficiently stabilized in a total contact cast or non-removable knee-high device

Monitoring Disease Activity

• Use serial skin temperature measurements of affected and unaffected limbs to monitor disease activity 1
• Do not use soft tissue edema alone to determine remission 1
• Consider temperature measurement, clinical edema, and imaging findings together when concluding that active CNO is in remission 1

Critical Pitfalls to Avoid

Common mistakes that lead to poor outcomes:

• Delaying immobilization while awaiting imaging results—this allows progressive deformity 1
• Using inadequate offloading devices (below-ankle devices) that fail to immobilize the affected joints 1
• Misdiagnosing CNO as infection or gout, leading to inappropriate treatment 1
• Failing to assess for peripheral arterial disease, which is present in 20-40% of diabetic foot patients and significantly impacts healing 1
• Assuming normal inflammatory markers rule out CNO—these blood tests are not useful for diagnosis 1

Long-Term Management

After remission is achieved, prescribe customized footwear and/or orthoses that accommodate and support the foot shape to prevent reactivation (Strong recommendation; Moderate certainty). 1 When deformity and joint instability are present, use below-knee customized devices for additional protection. 1

Multidisciplinary care involving infectious disease specialists, surgeons experienced in diabetic foot care, and podiatrists improves outcomes. 1