Diabetic foot ulcers affect 15-25% of patients with diabetes over their lifetime.
Appropriate workup and management of diabetic foot wounds is a crucial skill for anyone interested in internal medicine.
Here are my top pearls on the topic!
- Thread -
Here's a quick TLDR!
First, I didn't appreciate how grim the prognosis is for patients with diabetic foot wounds.
Some stats:
50% of diabetic ulcers become infected
20% of diabetic foot infections lead to some type of amputation
The 5-year mortality after amputation is >70%
Shocking
If revascularization is not possible or unsuccessful and/or the tissue is necrotic or gangrenous and poses a risk to the patient’s life, amputation may be the only viable option for management.
Diabetic foot ulcers lead to over 1 million amputations annually.
The most important risk factors for the development of foot ulcers include poor glucose control, peripheral arterial disease (PAD), neuropathy, renal disease, smoking, the presence of a callus, and edema.
The pathophysiology of foot ulcers:
- Loss of sensation from peripheral neuropathy leads to repetitive, unnoticed traumas
- Motor neuropathy leads to abnormal walking and pressure points
- PAD leads to impaired wound healing
Hyperglycemia itself leads to the formation of advanced glycation end-products (AGEs).
AGEs prevent the migration of inflammatory cells to wounds and can cause direct microvascular damage.
The plantar surface of the metatarsal head is the most common location for foot ulcers.
Other common locations include the toes and heels.
These are common pressure points and sites of repetitive trauma.
Frequent foot exams are crucial.
This is the checklist I use when admitting patients with diabetic foot wounds.
Don't miss nec fasc, gas gangrene, osteomyelitis, or limb ischemia.
Here's how I approach the HPI intake.
Ankle-brachial index (ABI) testing is often done prior to any procedures (i.e amputations) to assess for PAD and the need for revascularization to ensure proper wound healing.
Its compares the pressure in the ankle vs arm
PAD is severe if the ABI is less than 0.4
ABI can be affected by the presence of calcified or incompressible arteries, particularly in patients with diabetes or advanced age.
In such cases, the ABI will be > 1.4
Angiography may be needed to actually visualize blood flow and sites of stenosis.
Xrays can detect gas and the presence of bone changes in patients with diabetic foot wounds.
However, MRI is the most sensitive for diagnosing osteomyelitis.
MRI is 90% sensitive, 82% specific for osteomyelitis, with a high NPV
The LR is 0.14 if the MRI is normal
Erythrocyte sedimentation rate (ESR) is a non-specific inflammatory marker.
It measures the rate at which RBCs sediment in blood (mm/hr).
This reflects the level of plasma proteins (fibrinogen, immunoglobulins) which increase inflammation.
It rises and falls slowly
C-reactive protein (CRP) is a more specific marker for acute inflammation.
It’s a protein produced in the liver in response to inflammation.
It rises and falls quickly and the levels aren’t impacted by plasma components.
It is useful for monitoring response to treatment
Osteomyeltitis without source control (i.e amputation) is usually treated with at least 6 weeks of antibiotics guided by cultures from a bone biopsy.
If source control is achieved, treatment can be much shorter, often 2-5 days.
I found this brief thread highlighting some key takeaways from the 2023 guidelines to be really helpful!
Thanks @Factor_XII !
twitter.com/Factor_XII/status/1719094302939455940
Link to the guidelines: pubmed.ncbi.nlm.nih.gov/37779323/
My favorite review articles on the topic:
A @JAMA_current Review from 2023
pubmed.ncbi.nlm.nih.gov/37395769/
A @NEJM Review from 2017
pubmed.ncbi.nlm.nih.gov/28614678/
As always, here's the One-Pager for admitting patients with diabetic foot wounds!
You can download a PDF version on the @pointofcaremed website.
And here's the full video breaking down a systematic approach to admitting patients with diabetic foot wounds!
twitter.com/ROKeefeMD/status/1732885333480448438
You can find all of the full episodes on Spotify and YouTube!