Orthotic Management for Pediatric Equinus and Crouch Gait - Which Approach Works Best? Brief Overview and a Call for Comparative Effectiveness Research
Current orthotic management approaches were built on the specialty practice of various pediatric physicians (orthopedic surgeons, physiatrists, neurologists), pediatric physical therapists, and pediatric orthotists laboring to help children with cerebral palsy (CP).
These pioneers worked in the areas of:
- Biomechanical structure and function of the musculoskeletal system
- Gait analysis, (emergence and refinement)
- Application of sensory motor integration theories to orthotics, (arising from neurodevelopmental techniques and advances in thermoplastics materials/process which greatly influenced current practice away from the metal and leather days)
Many approaches have well known advocates and ardent followers. More recently, new approaches have emerged including the concepts of shank kinematics, more robust leaf spring dynamic response AFOs (thermoplastic and carbon) and adjustable dynamic approaches capable of balancing ground reaction forces (GRFs). In addition, emerging evidence for neuro-plasticity from basic science and clinical research has shed new light on the potential for both improved (and reduced) orthotic management outcomes for children with cerebral palsy. On the side of improved outcomes, neuro-plasticity may allow for the refinement of orthotic management to specifically alter the adaptive pattern of children with CP in a positive way. Therefore, this underscores the importance of translational orthotic research to leverage potential neuro-plasticity, as well as seeking a stronger evidence base to compare current approaches against the backdrop of emerging science and evidenced based practice to optimize orthotic management. Moreover, patient outcomes for orthotic management need to be based more on the patients achieving a higher level of activity and participation as described in the International Classification of Function (ICF). Finally, research should explore the underlying mechanisms of action, if any, of the various approaches to orthotic management to more positive outcomes.
The following represents an admittedly non-scientific survey and opinion of current practice based on the observations of the author.
Medicine and Accompanying Orthotic Treatments
The paradigm practiced by the many pediatric physicians is one that often advocates the use of ankle foot orthoses (AFOs) with the greatest amount of coronal and sagittal control of the foot ankle complex in the presence of equinus gait, crouch gait, and their variants.
For equinus gait, AFOs tend to be solid or articulated with rigid plantarflexion stops (Figure 1 ). In the presence of spasticity limiting R1 "angle of catch," botulinum toxin is often used to seat the heel and keep the ankle at 90 degrees. For myostatic gastroc contracture, surgical lengthening is often the treatment of choice and is typically employed later in childhood as a single procedure or as part of single event multi-level surgery(SEMLS). The day time AFO is often meant to preserve range of motion from botulinum toxin, serial casting and surgery, possibly even more so than to restore "normal" gait. If the AFO design ignores lack of available dorsiflex-ion range with knee extended and pretensions the gastrocnemius to seat the heel, it may lead to a flexed knee gait due to proximal gastrocnemius flexion action at the knee, contributing to excessive mid foot pronation with each step. Moreover, the plantarflexion stop may block the acceleration forces of third rocker.
For crouch gait, Ground Reaction Ankle Foot Or-thoses (GRAFOs) (Figure 2 ) are often used with as small a plantarflexion ankle angle as possible to assure swing clearance and maximum restraint of the overly advancing or inclining tibia. In practice, the optimal angle that benefits the patient can prove difficult to achieve with poor balance the result. If tolerated, plastic designs often deform or yield to a position of increased dorsiflexion over time that enables compliance for the patient. Dynamic hamstring limitations further reduce GRAFO effectiveness to address crouch and are often treated with botulinum toxin. Myostatic hamstring contractures may be handled surgically later in childhood as part of SEMLS. Casts and static night braces are often used in a further effort to preserve range of motion.
The paradigm practiced by many pediatric physical therapists often places emphasis on the need to provide the patient with their center of mass (COM) over a solid base of support (BOS) so that all aspects of sensory motor and balance training of the trunk and extremities can be developed optimally as the child grows. Ultra thin and flexible supra malleolar orthoses (SMOs) with dynamic coronal alignment and free sagittal motion at the ankle are the preferred approach (Figure 3 ). Dynamic ankle limitations from triceps surae spasticity or lack of muscle extensibility from myostatic gastrocnemius contracture are often treated with serial casting of the ankle, despite the fact that this muscle originates above the knee. If the child makes forefoot contact with their SMO, a toe to heel gait with loss of forward tibia progression and knee hyperextension are common in equinus with unilateral involvement. For bilateral equinus or crouch gait, the SMO provides no deceleration forces at the ankle for shock absorption at weight acceptance, nor can it control an overly advancing and inclined tibia from mid-stance through terminal stance. Flexible AFO concepts above the ankle rely on subjective stiffness choices in trim-lines and plastic thickness to control sagittal alignment, selected upon recommendation of the physical therapist. Coronal foot and ankle alignment and total contact sensory input through the plantar aspect of the foot are the priorities stated by both advocates and followers of this approach for sensory motor learning from the ground up.
There are many approaches practiced by pediatric orthotists. Individual practice tends to be dictated more by the paradigm of the prescribing physician or referring pediatric physical therapist.
Leading pediatric orthotists tend to integrate COM and BOS flexible SMO concepts within AFO designs, both articulated and solid depending on the weakness or tone of the patient and referral preferences. Gastrocnemius and hamstring dynamic and static limitations may be managed conservatively with dynamic therapeutic bracing used at rest or at night (Figure 4 ), often in conjunction with botulinum toxin. Designs for equinus gait may incorporate swing dorsiflexion assistjoints and plantarflexion stops. Designs for crouch gait may be GRAFOs ([poup2]) or articulated AFOs with plantarflexion stops or dorsiflexion check straps, with many variants seen in practice. Very stiff carbon composite and thermoplastic leaf spring type AFOs are also being used to control alignment and to withstand heavy usage (Figure 5 a-b).
Emerging Orthotic Paradigms
One approach uses the concept that most, if not all patients, can benefit from an inclined shank to floor angle of 8-12 degrees in mid-stance. The design advocated to achieve this is known as an ankle foot orthosis footwear combination (AFOFC) (Figure 6 ). The AFOFC uses a solid AFO that accommodates any dynamic muscle limitations to achieve an optimal shank to floor angle through "tuning," In general the maximum dorsiflexion ankle angle with knee extended is used as the basis for the initial solid design according to an algorithm to achieve the desired inclined shank to floor angle. For example, both equinus and crouch gait are first accommodated according to the algorithm in a solid AFO, placed within a shoe with an appropriately thick sole to achieve the desired shank angle for initial assessment.
Rocker modifications are employed as needed to simulate first rocker through weight acceptance, second rocker, and to preserve the acceleration forces of third rocker, since the anatomic ankle is no longer free. Iterations of AFOFCs (the solid AFO and shoe/sole mods) are evaluated using a gait lab, video vector analysis, or slow motion video. Myostatic gastrocnemius contractures are purportedly managed by active stretch in mid to late stance with each step, assuming the hip and knee have adequate extensibility to be fully extended. It has been suggested that the whole AFOFC design can lead to active stretching benefits if used regularly for walking.
Another emerging approach is incorporating adjustable dynamic components into AFOs (Figure 7 ). The adjustable dynamic ankle components shown in Figure 7 allow 40 degrees of dorsiflexion motion and 40 degrees of plantarflexion motion but with dynamic assistance and resistance. Advocates of this approach (including the author) incorporate the COM and BOS flexible SMO concepts for coronal alignment and selectively augmented function of the tibialis anterior and gastroc-soleus to influence swing prepositioning and stance phase biomechanics. For equinus gait, this is done with independently adjusted assistance to dorsiflexion in swing and resistance to plantar flexion in early stance, augmenting eccentric work of the tibialis anterior and to independently adjusted resistance to dorsiflexion and assistance to plantarflexion after mid-stance to maintain acceleration for third rocker. For crouch gait, the plantarflexors are augmented from foot landing throughout stance to aid loading response and to maintain dynamic balance over a solid base of support. For both equinus and crouch gait, lack of muscle extensibility to the gastrocnemius is handled with trial lifts at fitting to establish proper loading of the foot in stance. Dor-siflexion and plantarflexion resistance are fine-tuned iteratively through observation with the AFO on the patient at initial fitting and at follow-ups, as necessary. Patient changes from treadmill training, balance training, botulinum toxin. etc. can be addressed with additional fine tuning. Myostatic gastrocnemius or hamstring contracture is managed at night through dynamic therapeutic bracing (with or without botulinum toxin). Human ankle motion in the day time AFO may optimize eccentric active stretch of the gastrocnemius and proximal muscles, while providing necessary first, second, and third rocker actions in the appropriate sequence as feasible for any given patient.