CORR Insights®: Military Service Members with Major Lower Extremity Fractures Return to Running with a Passive-dynamic Ankle-foot Orthosis: Comparison with a Normative Population

Where Are We Now?

An increasing body of evidence supports the idea that a passive-dynamic ankle-foot orthosis (PD-AFO) and return-to-run rehabilitation program (RTR-RP) can improve and restore high-level function for a myriad of problems (most notably, but not just, high-energy trauma) from the mid-tibia to the hindfoot [5]. Prior studies [3, 5] have shown that the brace and rehabilitation program can improve functional parameters and patient-reported outcomes at multiple study sites—beyond where the brace and program were developed at San Antonio Military Medical Center—and potentially decrease the likelihood of late amputation. However, studies have also demonstrated that persistent functional deficits remain [5], and that the brace and rehab program may be most beneficial for dedicated athletes pursuing impact activities, with negligible benefit in self-selected walking velocity and related gate parameters as compared to persons with transtibial amputations or in patients with pilon fractures [2, 6].

The study in this month’s Clinical Orthopaedics and Related Research® by Peterson et al. [4] compared the running characteristics of 10 athletic brace users (runners) to 15 matched control patients who had neither functional deficits nor any brace requirement. The study was the first of its kind to compare directly results using the brace and rehabilitation program with a normative population, and the authors confirmed persistent deficits among those in the brace/rehab group in Short Musculoskeletal Function Assessment subdomains as well as worse performance in several Comprehensive High-level Activity Mobility Predictor functional tests. The study is more noteworthy, however, for the absence of major differences reported in most running biomechanical measures, such as velocity, cadence, and stride length. The authors acknowledged some obvious constraints on generalizing these findings, the most important of which was the study population: motivated, high-demand brace users. It’s worth noting that six of 10 study patients remained on active duty in the military.

Based on these findings, surgeons can feel more confident in the likelihood of brace-program success in patients who are athletic, motivated, and desire to run. It appears that the PD-AFO and RTR-RP really cannot only help some patients run, but help them to do it pretty well.

Where Do We Need To Go?

The current study further highlights the benefits of the PD-AFO and RTR-RP in select patients pursuing running and impact activities. Still, many questions remain unanswered or require further exploration.

First, which patient(s) or clinical indication(s) are ideal for a PD-AFO such as this one? We have clear evidence that the PD-AFO and RTR-RP can be helpful for high-demand activities and motived patients, and likewise that these interventions don’t provide that much benefit for most patients whose activities consist mainly of things like simple walking [2-6]. In a recent review article, Franklin et al. [1] suggested that a simple posterior leaf spring brace could be adequate for lower-demand patients, with an off-the-shelf, dynamic brace being appropriate for patients seeking a little more daily activity. Custom, dynamic off-loading (CDO) braces like the PD-AFO would therefore be reserved for truly high-demand patients who remain dissatisfied with these readily available, relatively less expensive solutions. While that seems a reasonable place to start clinically, this approach also represents expert opinion and is (mostly) unsupported by data. So, does this approach work? And where are the key decision points to separate these cohorts based on patient and demand factors?

Further, what are the indications for this brace-rehabilitation package, and are the results the same in civilian patients who have experienced trauma? This is important because both the present study and others have acknowledged, essentially, that these are young, motivated, previously healthy, active-duty military patients and the results may not be generalizable to civilian patient populations. As we make these choices, we need to recognize that not all patients have the same premorbid health status, baseline function, or rehabilitation goals. Furthermore, this specific type of PD-AFO is expensive, the RTR-RP may be both expensive and time consuming, and neither may be fully covered as a healthcare benefit for many patients.

Next, can other PD-AFO braces perform similarly as well? “Same same, but different” is a common phrase in Thailand—it basically means “similar.” The PD-AFO in the current study [4] was the Intrepid Dynamic Exoskeletal Orthosis (IDEO brace) and has been referred to as the latter in most prior studies. Still, other studies [1] refer to this class of brace as a CDO, which I mentioned previously. Words matter, because the original IDEO and RTR-RP are technically only available to the military and are, as noted, both labor- and time-intensive as well as expensive. However, the ExoSym™ (Hanger Clinic) is available to civilians and was developed by the prosthetist-orthotist who created the first IDEOs. Additionally, there are semimodular, customizable braces purported to have similar benefits, such as the Phat Brace (Phatbraces) and the ReAktiv Modular Dynamic Brace (Fabtech Systems LLC). So, we will eventually need to know if other CDOs perform the same, or are “same same, but different…”

Also, in terms of rehabilitation, how much RTR-RP is enough? In a prior, multimilitary center study, we noted that participation in the actual RTR-RP was variable [5]. Many patients completed the full or part of the program, but some patients literally took their brace and ran (or limped?) away. Participation did not seem to affect outcomes as long as the patient participated in some of the program. Even with that caveat, we were unable to discern whether it was the RTR-RP or the motivation to participate that made the difference.

Finally, what is the role of the PD-AFO and RTR-RP as a temporary rehabilitation tool? In the same prior study, my coauthors and I [5] proposed the concept that, in certain patients, the IDEO brace and RTR-RP may function as a rehabilitation bridge to higher demand activities but may not be required indefinitely—the brace and program as bridges to their own obsolescence. Additionally, prior studies have reported at longer follow-up that not all patients continue using the IDEO [3, 5]; was this due to abandonment in disgust, because the brace broke and pursuing a replacement was difficult, or because (with return of strength, motion, and/or function) the brace was no longer necessary?

How Do We Get There?

It’s impossible in a short commentary to provide a detailed discussion of each question mentioned above, and there are other questions worth investigating. So rather than just proverbially “dropping the grenade and walking out” (this is a military symposium, after all), I’ll try to briefly hit some high points.

To ascertain which athletic patients benefit most from this brace, we simply need more data from additional patients with carefully curated indications and outcomes. The answer regarding brace-program use among civilian patients is probably “yes, but …”. Just as not all military patients appear to benefit the same from a PD-AFO and RTR-RP program. There are certainly civilian trauma patients who are younger, active, and motivated (whether due to athletic pursuits or blue-collar vocations) and who would probably enjoy similar benefits. The aforementioned military-to-civilian applicability caveat is always important to mention, but is sometimes overemphasized. The first civilian studies utilizing CDOs and an RTR-RP should focus on and target this higher demand subgroup of civilian patients.

Future studies should also follow-up (perhaps even after a “primary results” paper has been published) to determine to what degree brace use was continued long term and, if not, when and why it was discontinued. These answers are also likely to prove important for ensuring payors cover the costs of the brace(s) and the associated rehabilitation. In the meantime, the present study provides additional evidence of relative brace-program success in motivated users who just want to run.