In a follow up to our coverage of post-stroke orthotic management, Roy Bowers, prosthetist/orthotist and senior lecturer at the National Centre for Prosthetics and Orthotics (NCPO), University of Strathclyde, Glasgow, Scotland, talks with The O&P EDGE about his perspective on lower-limb post-stroke orthotic management.
The O&P EDGE: Is there a “golden period” following stroke during which it is most beneficial to the patient to be fitted with an orthosis? Does this vary depending on the age of the subject?
Bowers: I think this is really the $64,000 question, and I don’t believe we yet have a definitive answer. My personal belief is that intervening at an early stage to address the biomechanical challenges facing stroke survivors is the right way to go, and may make recovery less of a challenge for them. I don’t know that this varies with age.
Whenever we “see” there is a biomechanical abnormality-and I don’t necessarily mean using complicated gait analysis systems-I think it is important to “normalize” the biomechanics, and therefore the patient’s gait, while he or she is first learning to walk again, rather than have them learn a gait pattern that is quite abnormal and then try at a later stage to “unlearn” that and learn something else when someone finally decides that they are not progressing and recommends an orthosis. Normalizing the external biomechanics is the key.
My experience is that although I can still improve gait in patients many years after a stroke using a custom AFO, many find it hard to maintain this improvement, often reverting to their old asymmetrical walking pattern. Maybe the fact that they have already learned an abnormal gait pattern works against them when we intervene later on. Maybe there are secondary soft-tissue changes that have developed because of the poor walking pattern. Maybe patients only have one good shot at motor re-learning after a stroke. The ones who learn an appropriate gait at an early stage seem better able to maintain it in the longer term.
I am happy for patients to discontinue orthosis use when they can demonstrate that they no longer need it. For many patients, the AFO is a therapeutic device on their road to recovery, while for others it will be something they will always need. Having said that, there is little in the published literature to say that early intervention is optimal although there is an interesting paper by Wang (2005) that reports improvements in walking speed and cadence in patients less than six months post-stroke, but not in those more than six months post stroke. In general, I have to say that the literature is disappointing and leaves many questions unanswered.
The O&P EDGE: What orthotic solutions have worked best for subjects in stroke recovery cases you have studied? What has changed about such orthotic treatment, improved by our better understanding of stroke? Are there new orthotic solutions that are performing significantly better than their predecessors-specifically hip-knee orthotic considerations and solutions, as well as foot/ankle orthotic considerations and solutions?
Bowers: I know that some of the new stance-control KAFOs are delivering nice results, but for me the custom solid AFO is my orthosis of choice for most patients, certainly those with the most complex problems. I say this because they need it, not because of dogma. A solid AFO is a really powerful biomechanical tool, provided it has been cast at an appropriate angle and “tuned” to optimize its effect. What I mean is that the AFO needs to accommodate gastrocnemius when it is short. An AFO that holds the ankle in a position that is more dorsiflexed than can be achieved with the knee fully extended will actually limit knee extension when the patient needs it in late stance. This has a negative effect on kinetics, particularly at the hip.
“Tuning” AFOs, essentially by changing the angle of tibial inclination using wedges, is a concept that has been around in the treatment of cerebral palsy for a number of years, and there is growing evidence of its benefit. It is of equal value when treating stroke and should be mandatory when using solid AFOs, just like aligning a prosthesis is something we all take as a given. I think aligning an AFO is critical when dealing with neurological impairment. Compared to when I started out in this profession, the main thing that I do differently now is to tune my AFOs to normalize the external moment at the knee and the hip. When we get this right, the benefits for patients are considerable. In truth, I now believe that influencing the hip is perhaps the most important thing an AFO does after a stroke.
The O&P EDGE: What about FES systems such as the WalkAid and Bioness L300? Is this the direction we are going/should be going, instead of with custom orthoses?
Bowers: I have no experience of using these systems, but I am not convinced that they can address the very significant stance phase problems facing many stroke survivors as well as a good custom AFO can. To me, improving stance, specifically late stance, is the key function of an AFO, and one that produces benefits that improve swing phase also.
The O&P EDGE: What do you foresee in the future for stroke victims, vis a vis orthotic solutions?
Bowers: Earlier intervention with AFOs, more use of AFOs as training or therapeutic devices, and a better appreciation of the effect that a good AFO can have on hip kinetics. I believe there are neurological effects of AFOs that have not yet been fully investigated, both on the upper limb and on the initiation of swing phase. Some of the work done on “central pattern generators” in the spinal cord are interesting, as they fit nicely with the concept of using an AFO to create a hip extension moment in late stance, offloading the hip extensor muscles and stretching the flexors. These factors seem to be important in initiating flexion of the limb at a spinal level. I also foresee more evidence emerging of AFOs not only maintaining muscle length, but actually increasing it. There is not much in the way of longitudinal studies on AFO use in the published literature.
The O&P EDGE: Are there any other thoughts you would like to share on this subject?
Bowers: It seems quite perverse to me that we expect people with neurological damage to deal with greater biomechanical challenges than the rest of us have to address, and with fewer physical resources at their disposal. This is a “double-whammy” if ever I saw one. If we can change the biomechanical challenge to make it more “normal,” then maybe patients will find it easier to deal with. This is not just about reducing the external moments, for example preventing knee hyperextension by reducing an excessive extension moment. It is also about replacing completely abnormal moments with more normal ones. A good example of this is when plantarflexion of the foot leads to an external flexion moment at the hip at a time when it is normal to have an extension moment (mid-to-late stance). This means that to try to stabilize the hip, patients have to activate their hip extensors at a stage in gait where they never previously did it in their life! How are patients with a damaged neurological system expected to deal with that?
As I said, I find that much of the literature is disappointing. There is often not enough information on the characteristics of the patients, or of the orthoses, to convince me that the prescribed device is appropriate, or to enable me to reproduce the intervention in clinical practice. This is a concern to me as there are many who are skeptical about using orthoses in neurological conditions. If we are not demonstrating benefit with our interventions, perhaps in some cases because we are investigating the wrong orthosis, or the correct orthosis in the wrong alignment, then we may convince the skeptics that their skepticism is justified….
The O&P EDGE: I am sure our readers would also be very interested to hear about the new best-practice statement Scotland has developed concerning the use of AFOs following stroke.
Bowers: This is an initiative by the National Health Service (NHS) in Scotland, more specifically by NHS Quality Improvement Scotland (NHSQIS), in collaboration with the NCPO at the University of Strathclyde. I was the specialist advisor and project lead for this work. Allied health professionals in Scotland had previously identified AFO use after stroke as a clinical improvement priority as there appeared to be wide variation in practice, poor understanding of the actual role of orthoses, and a lack of evidence on which to base practice. The best-practice statement (BPS) is the way that guidance is being provided. A group of clinicians from different backgrounds involved in stroke rehabilitation worked together to develop the BPS and agreed on its recommendations. There has been wide multidisciplinary consultation on two separate drafts of the BPS. The literature on AFO use has been reviewed and guidance has been provided under the following headings:
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Service planning, access to services, and clinical governance.
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Screening and referral.
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Patient assessment and indications for different AFOs.
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Biomechanical effects of AFOs.
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Non-biomechanical effects of AFOs.
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Review, monitoring, and follow-up.
In addition, we have provided “educational material” in the form of normal and pathological biomechanics and the indications for different AFO types. The statement is expected in print by mid-September, and the full document will be available online on the NHS Quality Improvement Scotland (NHSQIS) website www.nhshealthquality.org
