Bracing the Intrepid

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By Phil Stevens, MEd, CPO, FAAOP

The U.S. Army had a problem: The majority of its soldiers' combat wounds sustained while serving in Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom were extremity wounds. Explosive injuries with open fractures, collectively referred to as high-energy lower-extremity trauma (HELET), were commonplace. Advances in surgical techniques allowed attempted salvage procedures for many of these limbs. However, the commonly accepted standard of a successful limb salvage procedure- pain-free standing and walking- was inadequate for this highly active group, many of whom wanted to return to active duty. Further, patients who underwent limb salvage were doing their rehabilitation side by side with those who had experienced lower-limb amputations and watching them return to higher levels of function much more quickly. Established orthotic technologies were attempted, including off-the-shelf (OTS) plastic and carbon fiber AFOs and custom carbon fiber AFOs, but proved inadequate to restore these soldiers to their desired levels of function. So the rehabilitation team at Brooke Army Medical Center's Center for the Intrepid (CFI), San Antonio, Texas, developed its own energy-storing carbon fiber orthosis, the Intrepid Dynamic Exoskeletal Orthosis (IDEO). This article reviews a series of publications outlining the development of the IDEO; the levels of functional return experienced by some of its users; comparative outcomes between it and other orthoses; and the role that the associated training appeared to play in overall rehabilitation.

The First Case

The first publication to address the IDEO was a case study that describes the rehabilitation progress of a 29-year-old serviceman who was injured in a rollover motor vehicle collision in June 2009.1 He sustained a severe open ankle fracture and was evacuated, first to Germany, and then to San Antonio, where it was determined that reconstruction of the ankle was unlikely to succeed due to the complex nature of the fracture pattern, substantial bone loss, and ligamentous instability. Instead, an acute ankle arthrodesis was performed with excision of the devitalized distal fibula. The arthrodesis was held in position with a circular external fixation frame. A few days after its application, the fixation frame was fitted with a custom footplate to allow the patient to begin weight bearing through the limb. Intense physical therapy followed. By September the fusion was found to be complete and the fixation frame was removed, replaced by a CAM walker, and followed by a cautious return to weight bearing. By December, about six months after his initial injury, he had progressed to full weight bearing and had discontinued the use of the walking boot.1

Soon afterward, he was fitted with a commercially available carbon fiber AFO, which allowed him to run again and generally return to high-intensity exercise. However, he reported that the brace was uncomfortable after several hours of use and was difficult to don. In June 2010, he was fitted with an early version of the IDEO and observed significant improvements in both comfort and function. In July 2010, about 13 months after his original injury, he was declared fit for return to active duty.1

The Design

So what is it that makes the IDEO unique? In the body of the case study, the authors described how in the months leading up to the development of the IDEO, HELET cases were commonly treated with plastic OTS AFOs. While this intervention was generally associated with a return to community independence, it did not facilitate the return to impact, agility, and running exercises that some people with lower-limb amputations were able to perform shortly after rehabilitating from their amputations and being fitted with prostheses. Splitting their time between HELET and lower-limb amputation cases, the CFI team began to look for ways to mimic the energy-storing properties of lower-limb prostheses. Properly designed, a deflecting carbon fiber AFO could absorb energy in late stance and return it as ankle power during initial swing.

The original version of the IDEO comprised a proximal ground reaction cuff and a distal, carbon fiber-reinforced supramalleolar orthosis (SMO) connected posteriorly by a carbon fiber strut. This combination of a traditional ground reaction AFO coupled with controlled ankle mobility showed initial promise, with patients citing increased subjective functional abilities, improved stability, accommodation of uneven surfaces, variable walking speeds, and the ability to run.1

Additional refinements took place in the shape of the plantar surface of the SMO segment. Beginning at the heel, the authors described the use of a three-quarter-inch heel cushion that decreased the impact on the limb during initial loading, while bringing the forefoot quickly to the ground. From here the footplate featured "a gradual roller shape," beginning just distal to the heel cushion, reaching its apex at the metatarsal heads, and culminating in a "dorsiflexion radius design." It's a shape the developers claimed was inspired by the design of many of today's prosthetic running feet.

Further experience with early versions of the IDEO suggested that the proximal ground reaction component of the device could also be used to obtain a degree of proximal off-loading of the compromised distal ankle. By sparing these painful areas of the limb from some of the impact forces associated with the abrupt loads of elevated activity, the brace could serve to reduce pain while addressing the concomitant functional deficits.

Returning to the parallels with high-performance running feet, the CFI team recognized that the ability to align a more posterior placement of the foot might be beneficial for some patients. This was accomplished as the original struts were replaced with modular Littig™ struts that could be mounted to lamination plates attached to the posterior surfaces of the proximal cuff and distal SMO segments. In addition to the increased dynamics and power of the larger strut, the alignment of the device could now be refined by 5-7 degrees in dorsiflexion/plantarflexion, internal and external rotation, and inversion/eversion. Additionally, the strut itself could be exchanged for one with a higher or lower resistance.1

Once the appropriate alignment and stiffness had been determined using the modular Littig system described above, the authors described a "Clever Strut" nonmodular IDEO system in which the Littig strut was replaced with the medi USA Clever Bone prosthetic pylon system. This refinement was described as demonstrating increased energy return, improved torsional dynamics, and improved responsiveness to the patient.1

Expanding Activity Bases

The original IDEO users were a select cohort of patients. Not only were they a group of young men from very fit, athletic backgrounds, but they also received extensive, intense physical training as part of CFI's Return to Run Clinical Pathway. The next IDEO-related publication reported on the extent to which the IDEO, combined with a very intense, structured physical training program, allowed patients to return to running and other athletic activities.2

For the ten patients included in this first small cohort study, the training program began well before receiving an IDEO, while the subjects were still in their external fixation units waiting for the fusions to heal fully. This "in-frame" training phase was followed by the "brace" phase, both of which ultimately included aggressive strength training, plyometrics, and power and agility training. In addition, patients received targeted running retraining on the treadmill and the track once they entered the brace phase of this tailored clinical pathway. Subjects were trained to use a mid-foot strike rather than a conventional heel strike and were provided additional feedback on developing running mechanics. Initial distances were intentionally kept short, followed later by progressive increases in distance. Within the bounds of this observational study, the ability to run was defined as the ability to run for two miles, nonstop, on a treadmill.2

All of these subjects were treated at CFI; they were 29 years old on average, and had injuries that included fractures of the tibia, fibula, and calcaneus. Within this cohort, eight soldiers successfully returned to running as defined by the study parameters, including a single subject who completed a half and a full marathon. The two remaining subjects were also able to run, but could not meet the criterion of two miles without stopping.2

In addition to the ability to run, all ten subjects were able to return to a structured weight lifting program. Seven subjects were able to cycle, three returned to playing basketball, three to golf, and two to softball. Two subjects completed mini-triathlons (a two-mile run, five-mile bike ride, and 500-meter swim). Three subjects were able to redeploy in combat roles.2

Isolating the Effect of the IDEO

Given the unique characteristics of the study subjects as young and generally otherwise healthy males with access to intense physical training resources, it is reasonable to ask whether the observed benefits of the IDEO were products of the brace or due to these other favorable characteristics. This question was addressed in a later evaluation of 18 subjects with unilateral dorsiflexion and/or plantarflexion weakness who were evaluated across a range of functional tests while wearing an IDEO, an Allard Blue-Rocker™ AFO, a posterior leaf spring, and no orthosis.3

The tests used for this trial reflected the elevated activity levels of the subjects being evaluated. Some were fairly basic, such as self-selected walking velocity along a 15-meter walkway and a timed stair ascent in which subjects were asked to ascend a flight of 12 steps as fast and as safely as possible without using the handrail and making contact with each step. Also included was the timed Five-Times Sit-to-Stand Test (5XSST), in which subjects begin seated in a standard office chair and then stand up and sit down five times with their arms crossed, bringing the knees to full extension during standing. A 40-yard dash was also performed.

The last test used for analysis was the Four Square Step Test (FSST), described as a balance and agility test and requires some explanatory narrative.

Subjects begin by 1) standing in the bottom left quadrant of a cross shape on the floor. They are told to move both feet sequentially into each of the squares created by the cross with further instructions to move one foot at a time, keeping one foot in contact with the ground. The movement sequence for the test is 2) step forward; 3) side step to the right; 4) step backward; and 5) side step to the left, thus moving clockwise to return to the original square. The subjects then reverse this pattern by 6) sidestepping to the right; 7) stepping forward; 8) sidestepping to the left; and 9) stepping backward to return again to the starting position.

Ultimately, the performance with the IDEO across all of the prescribed tasks was significantly better than that observed in the other conditions with the sole exception of the 5XSST, in which the superiority of the IDEO only reached statistical significance when compared to the BlueRocker. Across the various tasks, the largest differences were observed in the 40-yard dash where the improvement seen in the IDEO was 37 percent faster than the nobrace condition, 34 percent faster than with the posterior leaf spring, and 28 percent faster than with the BlueRocker.3 Thus, the choice of brace design appeared relevant to the subjects' mean performance values. Indeed, the authors further reported that with the use of the IDEO, test subjects were able to perform the FSST and attain self-selected walking velocities consistent with those observed in noninjured control subjects.

The Role of Therapy

The previous study suggests that, the subjects' ages and access to intense physical training notwithstanding, the type of AFO used appears to affect the subjects' functional performances, particularly during athletic tasks. The last study to be considered asked the opposite question. Essentially, all things being equal, including brace design, what impact did the structured physical retraining have on a soldier's ability to return to active duty?4

In this retrospective analysis, researchers from CFI examined the records and status of all subjects fitted with an IDEO. These were subsequently divided into two groups, those who participated in the regimented Return to Run Clinical Pathway (n=115) and those who declined participation (n=31). The study authors determined that the return-to-duty rate among the first group was 51 percent (n=59), while the return-to-duty rate among the latter group was only 13 percent (n=4). While the soldier's rank and mechanism of injury appeared to contribute to return-to-duty rates across both groups, participation in the structured retraining program of the Return to Run pathway appeared to have a striking influence on the likelihood of a soldier's ability to return to active duty.4

Conclusion

Within today's academic literature, the contributions of lower-limb orthoses often tend to be marginalized, with little description of their design characteristics. In sharp contrast, the work of CFI in general, and that of the clinician who largely developed the IDEO, Ryan Blanck, CPO, in particular, provide a detailed narrative of the components and considerations that have gone into the IDEO approach. Within their targeted population of young, injured soldiers, the collective literature suggests that the IDEO, when coupled with CFI's structured Return to Run physical training protocols, enabled a number of patients to return to levels of function that were previously unattainable.

Phil Stevens, MEd, CPO, FAAOP, is in clinical practice with Hanger Clinic, Salt Lake City, Utah. He can be reached at

References

  1. Patzkowski, J. C., R. V. Blanck, J. G. Owens, J. M. Wilken, J. A. Blair, and J. R. Hsu. 2011. Can an anklefoot orthosis change hearts and minds? Journal of Surgical Orthopaedic Advances 20 (1):8-18.
  2. Owens, J. G., J. A. Blair, J. C. Patzkowski, R. V. Blanck, J. R. Hsu, and Skeletal Traum Research Consortium. 2011. Return to running and sports participation after limb salvage. Journal of Trauma 71 (1):S120-4.
  3. Patzkowski, J. C., R. V. Blanck, J. G. Owens, J. M. Wilken, K. L. Kirck, J. C. Wenke, and J. R. Hsu. 2012. Comparative effect of orthosis design on functional performance. Journal of Bone and Joint Surgery, American Volume 94 (6):507-15.
  4. 4. Blair, J. A., J. C. Patzkowski, R. V. Blanck, J. G. Owens, and J. R. Hsu. 2014. Return to duty after integrated orthotic and rehabilitation initiative. Journal of Orthopaedic Trauma 28 (4):e70-4.