Neurologic Developmental Gait Biomechanics and Pediatric O&P Management, Part II

Home > Articles > Neurologic Developmental Gait Biomechanics and Pediatric O&P Management, Part II
By Gerald Stark, PhD, MSEM, CPO/L, FAAOP(D)

Part 2- The second of this two-part series addresses how children's development impacts provision of pediatric O&P care.

Engineering and Design

In terms of engineering and design, children present a number of significant structural design challenges. Children are smaller than adults, but their peripheral limbs are proportionally much smaller. However, despite their size, children often generate force vectors that rival an Olympic athlete. While the prosthetic componentry is roughly 70 percent the size of adult componentry, the pediatric patient may push the physical limits of O&P design due to exponentially higher physical demands. Often, they not only subject the components to higher loads, but also impulse or mechanical shock from jumping, gymnastics, or sports.

Don Cummings, CP/L, FAAOP, the director of prosthetics at Texas Scottish Rite Hospital for Children, Dallas, points out, "In general, children are pretty upbeat and are usually wanting to move forward and get back to normal activities like running, jumping, and playing, so the prosthesis is a way to help them on their journey back to doing those things. More often than not, I'm challenged to provide prostheses that can hold up to the high activity level that most children who use prostheses achieve."

The small size of pediatric componentry combined with these high impulse loads present material and design challenges for engineers attempting to create devices with higher load ratings. Aluminum, commonly used in adult prosthetic components, is not particularly ductile  and fractures when the ultimate stress is exceeded, while materials such as steel, although heavier, will bend rather than fail catastrophically. With children, the main challenge is with durability and size, rather than weight. Cummings notes the improvement from simply adapting adult componentry. "Today we have better components that are specifically designed for children. This has changed a lot over the past decade and has made our job easier because we now have a greater selection of modular components, feet, knees, hands, etc. that are designed for the child."

Joanne Kanas, DPT, CPO, FAAOP, director of rehabilitation for the Shriners Hospitals — Florida, further emphasizes this need for durability. "Many components are now made in smaller sizes than ever before, such as pediatric knees, endoparts, etc., and they are more durable than ever before, but still they are not as durable for the ‘rough kids.'"

Coleen Coulter, PT, DPT, PhD, PCS, team leader of the Limb Deficiency Program, Children's Healthcare of Atlanta, points to additional challenges. "Technology is getting better and manufacturers are making more products that are size and user friendly, as well as sturdy, to meet the needs of the patient. We continue to develop components to accommodate toddlers and infants. However durability remains an issue. In some ways, prosthetic technology has not met the activity demands of the child. Some of these kids are just ripping up their knees since they are running step over step at ages two to four. We are just not there all the time to offer a comparable design to suit their needs."

In O&P this challenge is further increased by limited surface area to apply three-point corrective and supportive loads. One property that is an asset over adult O&P management is that the pediatric skeleton is still developing. This can be used to hold the proper alignment, while the force of growth can be utilized to allow migration into the proper position. Conversely, this same principle may produce adverse effects if there are strong forces applied in concentrated areas such as bony growth plates. An example would be suspension over distal condyles for lower- or upper-limb prostheses or improper fit of a scoliosis brace. Sometimes bony growth is restricted to create a more functional limb. An example would be epiphysis of the leg that is limited to create an end-bearing knee disarticulation level that allows for standard componentry in adulthood.

Bryan Malas, MPH, CO/L, director of Lurie Children's Hospital of Chicago, envisions more tools to monitor wear in the future. "In the next ten years adherence monitors for spinal and other devices are going to be more and more important so we can gauge how successful we are using a device. For example, we may find that 23 hours does not offer more correction than 18 hours, but certainly more than 12. We need to know the return on investment, not just of money, but time, to create a benchmark of what is most efficacious."

Goals and Expectations

By themselves, the factors of high load and smaller size would be considerably challenging. Additionally, there are the ever-evolving fitting priorities, functional goals, and expectations of the parents that must also be monitored and managed. Expectedly, emotion and anxiety are often intensified during the care and rehabilitation of children. To ensure personal trust and rapport with the parents, there must be constant communication and involvement with the parents, child, and the O&P clinician.

"You do want to keep things simple at first and provide a prosthesis that the child can use safely and comfortably and that the child and parents can take care of and apply and remove safely," Cummings emphasizes. That's another unique aspect of pediatric prosthetics; you are educating both the child and their caregivers about how to apply, remove, and take care of the device."

Difficulties can arise from simple misunderstandings with respect to the expectations and limitations of the technologies or processes. "I think that people look at the technology as though that is the end point," Malas adds. "We can look at spinal management and we are given guidelines, but we must be careful with more medically complex cases and understand a one-size-fits all cookbook approach is dangerous. We must know the limitations of mass-produced components and adjust accordingly."

Kanas agrees that custom solutions are essential. "Just because some new treatment comes out and it's advertised to ‘normalize tone' or some other goal, we need to see the evidence on outcomes. Every parent is looking for what will fix all issues. We all know that is probably not very realistic. Let's instead look at what we can do to positively affect function, outcome, and independence."

Unlike adults, the pediatric patient may not be able to understand or express their goals and opinions. It must be remembered that developmentally they are still learning basic human functions of communication, social interaction, mobility, and hygiene. The responsibility falls to the parent or guardian who must instruct and challenge the patient on daily basis. Often the parent and guardian are still dealing with the perception and anxiety of limb difference within their social context that may bring out their own biases.

It is essential that the practitioner attempts to anticipate challenges before they arise and to develop an overall strategy for the pediatric patient. This allows the parents, who are also new to the process, time to discern the future changes and discuss them rather making a series of tactical and stressful decisions. This is not to say tactical changes do not happen, but having an initial plan may account for areas of concern before they happen. Constant and empathetic communication is the most effective and critical tool for pediatric management.

Malas provides additional perspective. "One of the biggest changes over the years is that we have moved away from forced alignment. Using AFOs as a prime example, the desire was maybe to set the tibia at 90 degrees, and that was the best in terms of kinematics. But forcing that alignment in the AFO may not gain anything and even cause long term issues with the midfoot. What we are progressively doing long-term is perhaps iatrogenically causing greater pain."

It also helps to reaffirm the O&P goals that are prioritized as: 1) alleviate pain, 2) protect the segment, 3) accommodate/prevent further progression, 4) correct the deformity, and 5) optimize function. Another factor for pediatric patients is to protect articular surfaces by helping them to grow with correct alignment. Admittedly, these goals may be difficult to achieve all at once and may even conflict. However, the rehabilitation team, including the parents, physician, physical therapist, occupa­tional therapist, nurse, orthotist, and prosthetist, should confer often so that the priorities are reinforced, and consensus is found.

As to the future use of O&P technology for pediatric use, Kanas expresses her expectation. "I strongly feel CAD and 3D printing is the technology for the future. I am just not convinced we are there yet to realize all of what we need. But, when it is truly ready, those tools will enable custom, lightweight, strong, and functional designs that can be made quickly and adapted for the patient."

"Despite all of the things I have learned, I have so many more questions," says Malas. "It is the knowledge of the current research and proper management of that technology, at any level of complexity, that will continue to be imperative for optimal care."

Coulter points to increased availability of resources and communication. "Social media and the internet have established communication and linked groups together, so parents know exactly what is available. We have seen social media influencing the care children are getting, and parents come to healthcare requesting it. This is a great advantage because they are more informed, but it can also be a challenge if it isn't necessarily appropriate for their child." She also reinforced patient-centered goals. "The technology we implement should always have functional importance and priorities of the patient at as the direct goal, not the just use of technology itself."

Developmental and Social Factors

There are often other factors that surround pediatric patients. Brian Giavedoni, MBA, CP/L, manager of the O&P Department at Children's Healthcare of Atlanta, provides an example: "What clinicians need to remember is you do not outgrow a congenital anomaly. We don't turn 21 and things go away. They generally continue to progress, and lumping pediatric patients in with traumatic populations is simply not appropriate. How many practitioners understand all of the factors of an adult congenital patient? I mean, really understand, the total involvement of fibular deficiency and what that encompasses in terms of the care for the patient into adulthood?"

"The whole thing about limb difference in pediatric cases is that there may be multiple issues, not just the site of limb difference," Coulter adds. "Not only may there be additional issues more proximally, but there may be subtle issues contralaterally. Syndromes with pediatric cases are very common, much more so than with adults. We really have to do a total assessment to understand what is happening to the entire patient."

Cummings reminds us that we must remember the perspective of childhood. "One of our hospital's tenets is ‘giving children back their childhood.' I like that concept in that the absence of a limb does not have to rob a child of their childhood. While no prosthesis is perfect, we have the unique opportunity as prosthetists to design and build a device that in many cases restores the child's function to a level very close to normal."

Malas provides contextual perspective. "Treatment really has to be clinically appropriate, but it must also be balanced within the context and reality of the family. We may have a plan to satisfy the neuromuscular requirements, but if the child can't show up to clinic because there is no means for transportation, what good is it?"

"We have to look holistically and see if there something else going on, then we need to pick and choose what works for everyone," Cummings adds. "Each child is different and develops physically, cognitively, and emotionally at a different rate, so we also try to reduce anxiety about there being any schedule for these things to happen. But it is important to keep things simple at first and increase in complexity when the child is ready."

When providing pediatric O&P care, it's important to acknowledge that children's needs are different than adult's. Interventions must be designed that are appropriate for the child's developmental stage and family situation.


Gerald Stark, PhD, MSEM, CPO/L, FAAOP(D), is a senior clinical specialist at Ottobock Healthcare, Austin, Texas.