SLR - November 2021 - Brett A. Albert

Ultrasonographic Features of Acute Charcot Neuroarthropathy of the Foot: A Pilot Study

Reference: Mortada M, Ezzeldin N, Hammad M. Ultrasonographic Features of Acute Charcot Neuroarthropathy of the Foot: A Pilot Study [published correction appears in Clin Rheumatol. 2020 Oct 13:]. Clin Rheumatol. 2020;39(12):3787-3793. doi:10.1007/s10067-020-05107-2

Level of Evidence: IV

Scientific Literature Review

Reviewed By: Brett A. Albert DPM MHA
Residency Program: Hennepin Healthcare – Minneapolis, MN

Podiatric Relevance: Prompt and accurate diagnosis of Charcot neuroarthropathy (CN) continues to be a challenge. MRI is the present gold-standard but is unable to easily differentiate CN from osteomyelitis. PET-CT is a valuable emerging tool but is not readily available nor inexpensive. Ultrasound is a widely available technology but has a relatively high learning-curve for diagnostic use. It is also a relatively inexpensive resource that can potentially influence the workup of this complex disease.

Methods: Twenty-six patients with MRI-proven early stage CN were examined using ultrasound at the mid-tarsal and ankle joints. The level of synovitis present was graded, and the joints were inspected for presence of effusion, cortical erosions, and tendonitis. The exam findings were then compared to determine their diagnostic potential.

Results: The demographics of the 26 recruited patients were predictable for the target patient population affected by CN (38-67 years, BMI 35.9 +/- 4.3, 96.2 percent had diabetes mellitus with disease duration of 8.5 +/- 1.5 years). Ultrasound examination detected synovitis and effusion at 100 percent of mid-tarsal joints and 92.3 percent of ankle joints. Doppler activity was observed in 100 percent of mid-tarsal joints and 84.6 percent of ankle joints. Effusion was noted in 92.3 percent of ankle joints. Fibular erosions as well as tendonitis of the Tibialis posterior and the peroneal tendons were appreciated in a large majority of patients as well.

Conclusions: The authors of this study conclude ultrasound can detect a unique combination of active synovitis, tendonitis, and erosions that is a highly suggestive finding of CN. Early stage CN is especially difficult to diagnose as it is not visible on plain radiographs. Early changes of CN (bone marrow edema, microfractures) are also not detected on CT, and MRI is costly, less accessible, and does not easily differentiate CN from osteomyelitis. While it is not practical to send every suspected patient for a MRI or PET-CT, in-office ultrasound examination is beginning to prove itself as a viable and cost-effective tool in the workup of CN. This is a very early study, and much more research is required to quantify the sensitivity and specificity of this modality in the diagnosis of CN. 

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