TBI Testing for Wound Healing and Surgical Planning
Every surgeon and podiatrist knows the moment before a procedure when you need to be certain. Certain the tissue will heal. Certain circulation is adequate. Certain you are not setting your patient up for a complication that ends in a worse outcome than the one you were trying to fix.
That certainty has a name. It is called a Toe-Brachial Index exam, and for patients with diabetes, peripheral artery disease, or chronic non-healing wounds, it may be the most important data point in the room before you proceed.
And yet it remains one of the most underused tools in clinical practice.
What Is a TBI and Why Does It Matter?
The Toe-Brachial Index measures the ratio of blood pressure at the toe to blood pressure in the arm. Like the Ankle-Brachial Index (ABI), it is a non-invasive way to assess arterial perfusion. Unlike the ABI, the TBI is measured at the digital arteries of the toe using a small photoplethysmography (PPG) sensor rather than a Doppler probe and ankle cuff.
This distinction matters enormously in the patient populations most at risk.
In diabetic patients, medial arterial calcification frequently stiffens the vessel walls, causing ankle pressures to read falsely high. A patient with significant peripheral artery disease can return a normal or elevated ABI result simply because calcified vessels resist compression. That false reassurance is clinically dangerous.
The digital arteries of the toe are largely spared from this calcification process. That makes the TBI a far more reliable indicator of true perfusion status in diabetics and in any patient where calcified vessels are a concern. When the ABI misleads, the TBI tells the truth.
The Wound Healing Question No One Should Skip
Chronic non-healing wounds are one of the most complex and costly challenges in outpatient care. They are also one of the most predictable pathways to amputation when vascular status is not properly assessed.
A wound that is not healing is not simply a wound care problem. In many cases, it is a perfusion problem. If the tissue is ischemic, no dressing protocol, no debridement approach, and no topical treatment will overcome the fundamental deficit in blood flow. The wound cannot close because the biology required for healing is not present.
TBI thresholds for wound healing have been studied and published in vascular and wound care literature. A TBI below 0.70 is generally considered abnormal, with lower values indicating increasing severity of arterial disease. A TBI below 0.40 is associated with critical limb ischemia and a very poor prognosis for wound healing without revascularization. These are not arbitrary numbers. They represent a clinical decision point.
Before committing a patient to a wound care plan, before scheduling a procedure, before assuming that healing is possible, the TBI gives you objective data on whether adequate perfusion exists. That data changes the care plan. It changes the referral decision. It may change whether an intervention happens at all.
Before You Cut: TBI as a Surgical Planning Tool
For podiatrists and surgeons performing procedures on the foot and lower extremity, the TBI is not optional. It is essential.
Any incision into tissue that lacks adequate perfusion carries serious risk. Surgical wounds that open in an ischemic foot face the same healing barrier as chronic wounds. The procedural success becomes a clinical failure at the tissue level, and what begins as a corrective intervention can become the precipitating event for a non-healing surgical wound, infection, or ultimately, amputation.
The question every clinician should be asking before any elective or semi-elective foot procedure is simple: does this patient have adequate blood flow for this tissue to heal?
The TBI answers it.
A TBI performed before surgery gives you one of three outcomes: confirmation that perfusion is adequate and you can proceed with confidence, identification of borderline ischemia that warrants vascular consultation before proceeding, or clear evidence of critical ischemia that needs to be addressed before any elective intervention takes place.
In each case, you are better positioned to protect your patient than you were without the data. That is the entire point.
TBI in Diabetic Patients: A Non-Negotiable Assessment
Roughly 30 percent of diabetic patients have PAD, and because of the calcification problem discussed earlier, a significant portion of them will return misleading ABI results. In this population, skipping the TBI is not a neutral decision. It is a decision to operate or treat without adequate perfusion data.
Diabetic foot complications are the leading cause of non-traumatic lower-limb amputations in the United States. The pathway from wound to amputation is not inevitable. It is often driven by delayed or incomplete vascular assessment. Patients who receive timely, accurate evaluation of their perfusion status can be referred for revascularization when indicated, managed with appropriate wound care protocols, and protected from interventions that their circulation cannot support.
The TBI is the assessment tool that makes this possible in patients where the ABI falls short.
What TBI Testing Looks Like in Practice
One of the common barriers to TBI adoption is the assumption that it requires specialized equipment or a vascular lab. Neither is true.
TBI testing is performed using a small digit cuff placed around the toe and a PPG sensor to detect blood flow. The exam takes only a few minutes, can be performed by trained clinical staff, and integrates naturally into a standard office visit for any patient with diabetes, wounds, or PAD risk factors.
The clinical yield from that brief exam is significant. You gain objective perfusion data, a documented basis for treatment planning or referral, and a defensible record of vascular assessment in your chart. For wound care centers, podiatry practices, and any primary care office managing high-risk diabetic patients, TBI is a low-burden, high-value add to the standard workflow.
It is also reimbursable. TBI is included within CPT codes 93922 and 93923 when performed as part of a complete non-invasive vascular study, adding revenue while improving care quality.
The Cost of Not Testing
Consider the clinical and financial weight of a surgical complication in an ischemic foot. A non-healing surgical wound requires additional visits, additional treatment, possible hospitalization, and potential surgical revision. In a worst-case scenario, it progresses to infection and amputation. The patient carries a devastating outcome. The practice carries the burden of a complication that a five-minute pre-operative assessment could have prevented.
The TBI is not a barrier to care. It is a filter for unsafe care. It identifies the patients who need vascular intervention before they can safely benefit from the procedure you are planning. In those cases, the TBI does not delay treatment. It redirects it toward the intervention that actually helps.
For every patient where the TBI confirms adequate perfusion, you proceed with confidence. For every patient where it does not, you have protected them from a preventable harm.
TBI Is Standard on Every simpleABI Cuff-Link System
Every simpleABI Cuff-Link System from Newman Medical includes TBI capability as a standard feature. Whether you are performing single-level testing with the ABI-400CL, multi-level segmental studies with the ABI-500CL or ABI-600CL, or adding exercise and stress testing with the ABI-450CL or ABI-600CL, TBI is built in and ready to use.
That means every practice that already owns a simpleABI Cuff-Link System has everything needed to perform TBI exams today. And for practices evaluating which vascular testing system to bring in-office, TBI is not an add-on or an upgrade. It is included.
You can explore the full simpleABI Cuff-Link System lineup, including TBI capability, at newman-medical.com/simpleabi_cufflink_systems/.
If you’re looking for a more economical way to perform a TBI exam, the handheld manual simpleABI-300 system also has this capability.
For practices ready to take the next step, a free 30-minute consultation and demo is available online or in person. The conversation starts with your patient population, your workflow, and what complete vascular assessment looks like in your practice. No obligation, no pressure.
If you want to explore options on your own, take a look at The Ultimate Guide to PAD Testing: Finding Your Perfect simpleABI Match.
Because before you cut, you need to know. And now you can.