Charcot Joint: What do Emergency Physicians Need to Know?

Authors: Andy Wong, MD (EM Resident Physician, SUNY Downstate / Kings County Hospital) and Richard Sinert, DO (Professor of Emergency Medicine / Vice Chair of Research, SUNY Downstate Medical Center) // Edited by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit)

Case

A 71-year-old male with past medical history of poorly controlled diabetes, hypertension, and diabetic neuropathy presents to the emergency department reporting left foot swelling for three days. He notes left foot swelling and redness. When asked if there was any trauma, he replies, “I’m not sure as I can barely feel my feet”.

Vital signs include T 99.1F, Pulse 90, RR 18, 142/61, 99%RA, Glc 360. On exam, the patient has an edematous, warm left foot with erythema primarily over the mid-foot. There are hard callouses seen along the lateral and plantar surface, and the skin is intact. Distal pulses are strong and intact. Sensation is diminished all along the foot.

What diagnoses should you be considering? What tests should you perform and order?

Background

Charcot Joint is progressive deterioration of a joint seen in patients with peripheral neuropathy.  Jean-Martin Charcot and colleagues first described the disease, as it was caused by tertiary syphilis in the late 1800s [1]. However in the modern age, diabetes mellitus is the most common cause of this neuro-arthropathy, and emergency physicians must have a high index of suspicion to be able to differentiate it from other disease entities such as osteomyelitis, arthritis, or gout.

Pathophysiology

The pathophysiology of Charcot Joint is multifactorial, but ultimately it is a combination of mechanical and vascular complications from diabetes. Loss of pain sensation and proprioception may lead to repeated trauma, which results in joint laxity, joint instability, and the release of pro- inflammatory cytokines. This is further complicated by autonomic vascular reflexes that cause hyperemia, arteriovenous shunts, and periarticular osteopenia [2]. This eventually progresses to bony foot deformities, particular in the mid-foot [3].

Epidemiology/Presentation

Charcot Joint is estimated to affect 0.8%-8% of the diabetic population [4]. This risk is significantly increased with obesity [5]. The tarsometatarsal (Lisfranc) joint is the most common site of disease [2]. Clinical manifestations can be either acute or chronic. The classical acute presentation is sudden onset of unilateral warmth, edema, and erythema over the foot or ankle, possibly in the setting of minor trauma [6]. Over time, chronic deformities will form, such as collapse of the arch of the midfoot, bony prominences, and the development of “rocker bottom feet” [7]. Failure to detect and treat Charcot Joint early in its progression may result in significant complications ranging from difficulty ambulating to permanent disability or amputation.

Diagnosis/Evaluation

Given the acute symptoms of Charcot Joint as mentioned above, it may be tricky for the emergency physician to differentiate Charcot Joint and other conditions such as infection (cellulitis, osteomyelitis), gout, or osteoarthritis. On physical exam, the lack of an ulcer raises suspicion for Charcot Joint rather than infection [3].  Brodsky describes raising the affected extremity for 5-10 minutes in a supine position, and if the edema and erythema decreases, it is more indicative of Charcot process [9]. Laboratory studies may assist in distinguishing from infection, as Charcot Joint does not typically result in elevated WBC or CRP, though these are not definitive studies [10]. Synovial fluid analysis may help identify a gout process. An X-ray may help in evaluation if it is positive for Charcot Joint findings such as bony debris, loss of joint space, and osteopenia, but a lack of findings is not conclusive. To make things more complicated, be aware that Charcot Joint may be complicated by osteomyelitis or infected ulcers. Therefore, while physical exam, laboratory tests, and imaging can assist with diagnosis, no one modality is specific for Charcot Joint.

Treatment

It is important to recognize Charcot Joint early to prevent morbidity, as the management greatly differs from other disease entities. Patients should be referred to diabetic foot specialists where conservative management with pressure-relieving methods can be initiated. Total contact casting, which requires precise molding and frequent reapplication, is considered gold standard to offload weight [2]. Crutches and wheelchairs are also options. Gradually the patient is transitioned back to weight-bearing as erythema and edema resolve and radiographic findings are stabilized.

Take Home Points

• Consider Charcot Joint in the differential of the warm, edematous, erythematous lower extremity, especially in patients with diabetic neuropathy.
• If raising the affected extremity for 5-10 minutes leads to decrease in erythema, Charcot Joint may be more likely. WBC and CRP tend to be normal in Charcot Joint compared to infection.
• Early recognition and treatment by off-loading pressure on the foot leads to lower morbidity and better outcomes.

References / Further Reading

1. Womack, J., Charcot Arthropathy Versus Osteomyelitis: Evaluation and Management. Orthopedics Clinics of North America. 2017. 48(2):p241-247.
2. Sommer, TC and Thomas H. Lee., Charcot Foot: The Diagnostic Dilemma. Am Fam Physician. 2001. 64(9):p1591-1598.
3.  Bulent M. E, Lipsky BA, Savk O. Osteomyelitis or Charcot neuro-osteoarthropathy? Differentiating these Disorders in Diabetic Patients with a Foot Problem. 2013.  Diabetic Foot & Ankle. 4(1):p 21855
4. Rajbhandari, S., Jenkins, R., Davies, C. et al., Charcot Neuroarthropathy in Diabetes Mellitus. Diabetologia. 2002. 45(8): 1085-1096
5. Stuck RM, Sohn MW, Budiman-Mak E. et al. Charcot Arthropathy Risk Elevation in the Obese Diabetic Population. Am J Med. 2008. 121(11):p1008-1014.
6. Slowman-Kovacs SD, Braunstein EM, Brandt KD. Rapidly Progressive Charcot Arthropathy Following Minor Joint Trauma in Patients with Diabetic Neuropathy. Arthritis Rheum. 1990. 33(3):p412
7. Sinha S, Munichoodappa CS, Kozak GP.  Neuro-arthropathy (Charcot joints) in Diabetes Mellitus (Clinical Study of 101 cases). Medicine (Baltimore). 1972. 51(3):p191.
8. Lee C.R. Frykberg R. G. et al. The Charcot Foot in Diabetes. Diabetes Care 2011. 34(9): 2123-2129.
9. Brodsky JW. Outpatient Diagnosis and Care of the Diabetic Foot. Instr Course Lect. 1993. 42:p121–39.
10. Petrova NL, Moniz C, Elias DA, Buxton-Thomas M, Bates M, Edmonds ME. Is There a Systemic Inflammatory Response in the Acute Charcot foot? Diabetes Care.2007. 30: 9978.
11. Dahnert W. Radiology Review Manual 5th ed. Lippincott, Williams & Wilkins 2003.