Practice Perfect 774
Do Improved Radiographic Outcomes Equate to Improved Patient Outcomes?
Part 1: The Problem

When we were taught foot and ankle surgery in school and residency, we were generally taught two or three primary principles. These principles included the evaluation of weight-bearing radiographs with their various angles and relationships (think Meary’s angle, calcaneal inclination, etc) and several surgical procedures, each of which did something specific to the foot. We were trained to examine the dominant plane of deformity (as it related to flatfoot issues) or the center of rotation of angulation (CORA) – the apex of a deformity.

We were also taught a “biomechanical examination” of the lower extremity, measuring joint ranges of motion and relationships on actual patients. A thorough educational process would then corollate the patient examination with the radiographs.

Based on these principles, we were to choose one or more surgical procedures to normalize abnormal radiographic relationships and angles. Residency then taught us to execute those specific procedures in the operating room. This entire process is kinematic in its approach. Recall that kinematics in podiatry is that part of biomechanics that examines joint relationships (rather than kinetics, the part that identifies pressures and forces). The kinematic approach to surgery boils down – somewhat simplistically, I’ll admit – to “make it straight”.

Make it straight might look like any of the following examples. Correcting the first intermetatarsal angle in hallux valgus deformity would lead to “radiographic success.” Similarly, alignment of the talo-first metatarsal angle (Meary’s angle) in flatfoot surgery would indicate improvement in the deformity, as would a more parallel tibiocalcaneal angle on a calcaneal axial radiograph. The commandment “thou shalt not varus” in hindfoot fusions is well known to all foot and ankle specialists.

All of these cases are examples of kinematic approaches, but the one parameter that you may realize is not present in any of this discussion so far is that all-important patient outcome. Just because something is straight doesn’t necessarily mean we have resolved a patient’s complaint. And, on the other side of the coin, it isn’t always necessary to make a patient’s foot perfectly straight to effect successful outcomes.

Just because something is straight doesn’t necessarily mean we have resolved a patient’s complaint

Take hallux valgus as an example. It’s highly common for patients to undergo surgical correction that fails to completely eliminate all the deformity, yet resolves the complaint. This is especially true in those patients that have medial bump pain in shoes. Decreasing the size of the bump will decrease the symptoms. There’s also no shortage of patients who have undergone major hindfoot and ankle fusions, leaving them rigidly straight but still have chronic pain. I once performed a tibiotalocalcaneal fusion on a patient with severe arthritis and deformity after a motor vehicle accident. Initially, I was proud of my results with a solid fusion and rectus hindfoot but disappointed months later to find the patient remained painful, albeit less than before. Clearly, straight did not correlate with pain relief.

The question, then, is do improved radiographic outcomes (ie improved kinematics) lead to improved patient outcomes? Is there direct and clear research evidence that proves to a high level of certainty that improved imaging outcomes correlate with improvement in patient symptoms? What is the link between kinematics and kinetics? Are positional improvements markers of decreased forces and pressures on damaged structures? How can understanding these relationships help us make decisions?

The question, then, is do improved radiographic outcomes (ie improved kinematics) lead to improved patient outcomes?

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To that end, in the following weeks, this short series on surgical biomechanics will attempt to answer these questions. Stay tuned to see what the research tells us about these very important yet fundamental questions.

Best wishes.

Jarrod Shapiro, DPM
PRESENT Practice Perfect Editor
jarrod@podiatry.com

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