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Do Improved Radiographic Outcomes Equate to Improved Patient Outcomes?
Part 2: The Flatfoot Evidence

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Jarrod Shapiro, DPM, FACFAS, FACPM, FFPM, RCPS Glasg

Practice Perfect September 14, 2021

In last week’s Practice Perfect, I introduced a question that many might find pointless, but I consider to be very important: Do improved radiographic outcomes reported in the literature correlate with improved patient outcomes? Those that think this a pointless question may have assumed that this is obviously answered “yes” because of their own clinical and surgical experiences. However, I beg to differ.

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Just because we have a number of procedures to correct foot deformities, and those procedures may create a well aligned foot, doesn’t necessarily translate to improved patient outcomes. There may be other factors at play. For example, patients with well controlled hypertension may still have a heart attack; control of hyperlipidemia is another important factor in preventing heart disease. Similarly, in the lower extremity, creating a well aligned great toe may not necessarily alleviate the symptoms of end stage hallux valgus with hallux rigidus. Dealing with the arthritic process itself may also be necessary. Our goal today, then, is to examine the research literature as it pertains to flatfoot surgery and see if we can conclude that improvements in imaging parameters actually mean improved clinical outcomes for patients. Next week we’ll do the same for pes cavus surgery.

Now, before we get started, I’ll make a few disclaimers. First, due to lack of space (and to maintain reader interest) I’m picking a limited number of articles and not doing a systematic review. Second, there will be a publication bias toward articles that show a positive relationship between radiographic and clinical outcomes. It’s well known in the published literature that studies with negative results are published less often. Third, unless a study has been published that is specifically constructed to demonstrate a true cause-effect relationship between images and clinical outcomes, the best we will be able to conclude here is that there is a correlation between imaging and clinical outcomes. It is actually very difficult to prove there is an actual cause-effect unless a study was specifically structured to prove this hypothesis. Basically, we would need to randomize a large number of patients to either a less corrected versus more corrected group and then look at the radiographs and clinical outcomes of each. Deliberately limiting the surgical correction in some way is not ethical, so this can’t really be done. The best we can do, then, is to list a number of studies that report both radiographic and surgical outcomes at the same time, knowing that the more studies there are, the more likely the correlation is to be true. And that, my friends, is exactly what I’m going to do now. Let’s get to it!

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Medial Displacement Calcaneal Osteotomy

In 2015, Conti and colleagues examined the medial calcaneal displacement osteotomy (MDCO) in Johnson-Strom stage II posterior tibial tendon dysfunction patients, specifically looking to see if there was a relationship between heel position and patient outcomes.¹ They retrospectively reviewed the outcomes of 55 patients (55 feet, 20 males, 35 females, without significant demographic or radiologic differences) who underwent MDCO as part of a flatfoot reconstruction. They measured the following angles preop and postop: hindfoot alignment moment arm, Meary’s angle, TN coverage angle, and DP-talo-1st met angle. The follow-up period was an average of 23.5 months. They also surveyed patients preop and at least 22 months postop for pain, symptoms, activity level, sports activities, and quality of life using the Foot and Ankle Outcomes Score (FAOS) questionnaire. Statistical analyses were used to identify if there was a relationship between surgical correction and patient outcomes.

In summary, they found patients whose heels were corrected to a mild varus position (0-5mm) had statistically significant improvement in pain and symptoms, but no improvement in activity level, sports activities, or quality of life versus those left in a valgus heel position. One problem with this study was the relatively small number of patients in the groups and a lack of power analysis, so we are unable to determine an effect size. The bottom line, here, is there seems to be a correlation between a mild varus position of the heel and improvement in pain and symptoms in these patients, but this correlation is incomplete (because activity levels and quality of life didn’t change based on heel position). As stated above, other factors are also at work (including the other surgical procedures performed and likely other factors).

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Dynamic Flexor Hallucis Longus Tendon Transfer

In a somewhat similar study, Kim, et al in 2020², looked at radiographic and clinical outcomes of patients who underwent flatfoot reconstruction using a modified flexor hallucis longus tendon transfer to the base of the 1st metatarsal to assist with medial arch stabilization. This was also retrospective in nature but only included 14 patients. All patients underwent an MDCO and gastrocnemius recession. Radiographic angles were tracked pre- and postop, and clinical outcomes were recorded using the Foot Function Index (FFI) and the VAS scale, both at a minimum of two years follow up. For the sake of our discussion here, it’s not important to know the specific details of the angles or their specific results.  All radiographic angles improved significantly, as did the FFI and VAS scores. I’ll mention here the methodological issues are the same here as with the prior study (small group size and inability to determine effect size). Additionally, this paper provides five radiographic pre- and postop images, none of which show complete correction of the deformity. Strictly speaking, their analysis shows a correlation between improved radiographic position and patient outcomes, though if 5 of 14 patients don’t have correction, I can’t help but be skeptical that other confounding variables explain the improved clinical outcomes.

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The Cotton Osteotomy

Since we’ve discussed a calcaneal osteotomy and a soft tissue procedure, I can’t help but include one examining the Cotton osteotomy. Conti, et al³ did an analysis of radiographic and clinical outcomes of the Cotton procedure in 63 feet (61 patients). They retrospectively compared pre- and postop radiographic angles to results of the FAOS questionnaire at 24 months postop and found statistically significant improvement between the kinematic radiographic measures and the FAOS questions – as long as the size of the Cotton bone graft only mildly plantarflexed the medial column. They recommend against excessively plantarflexing the medial column to remove all residual forefoot supinatus. This study showed that correcting the forefoot deformity with this procedure correlated with better outcomes but only to a moderate degree. Again, other factors are at play.

Final Conclusions

Based on these three limited studies on patients in an adult acquired flatfoot population, we can conclude that there does seem to be a correlation between radiographic and clinical outcomes, but only up to a point. Overcorrecting deformities have detrimental effects, and each surgical procedure has its own side effects. It is these “effects” that tell us there is more to the story than simply “make it straight,” ie kinematics.

The biomechanical aspect that none of these three studies (and, in fact, many studies) do not examine are the kinetic effects. When we perform any surgical procedure, that procedure changes the position of bones and joints (kinematics), but their effects physiologically occur by changing forces about various joints in the lower extremity. It is these forces that actually lead to postoperative improvement in function and patient outcomes by reducing strain on damaged anatomy. More studies need to include the kinetic aspect for us to better understand the effects of surgical procedures.

My conclusion so far is that radiographic improvements are not one-to-one predictors of patient outcomes. Next week we’ll continue this exploration by looking at surgery for pes cavus conditions.

Best wishes.

Jarrod Shapiro, DPM
PRESENT Practice Perfect Editor
[email protected]

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