Understanding The Impact Of Gait Analysis

Author(s): 
By David Levine, DPM, CPed

There is a large untapped population of patients who need our biomechanical expertise and guidance. These are the patients who are currently seeing physical therapists, chiropractors, orthopedic surgeons and their family physicians for ongoing aches and pains that are sometimes in their feet, but often in other locations too. These are patients looking for answers to their foot, leg, knee, hip and back pain. Even though we do not directly treat ailments affecting other regions, we do understand the impact the foot has on the rest of the body. Certainly a static exam is an integral part of any exam we do, but it is the dynamic examination that will yield important clues. With these clues, we will be better at diagnosing and treating a variety of mechanical conditions that are affected by the foot. Just like taking an X-ray, assessing gait is a diagnostic exam that will provide important information. The more attention you give it in your practice, the more you will learn and the wider your eyes will open in learning how people function during gait. You can perform gait analysis in several different settings. The easiest technique is the simple hallway assessment. Having the patient walk back and forth in the hallway allows a view of both the front and back of the person. This is a quick and easy way to gain insight into function and is routinely done by most podiatric practitioners. It serves as a way to confirm the nonweightbearing examination performed in the exam chair. However, walking barefoot in a hallway with the pant legs bunched up around the knees can sometimes alter a person’s normal gait pattern. Sometimes the pant legs will fall, obscuring the very thing you want to see or patients will hunch over holding their pant legs up. Then in an effort to save time, the patient will be ushered back into the exam room, making for an incomplete assessment of what was originally intended. Unfortunately, this short walk may not be sufficient in the more involved biomechanical situations. How Multiple Camera Views Can Be Helpful In Analyzing Gait There are other options for assessing gait. By recording the hallway walking of a patient with a video camera, you will be able to at least save what you have for viewing at a later time. You can even play it back on the computer frame by frame in slow motion. This can become part of the medical record. Improving technology with digital cameras is making this even easier. Using video allows you to assess dynamic function. For instance, in a foot type that pronates a lot, you will see the first ray elevate, the longitudinal arch disappear and how this affects propulsion. You will also observe transverse plane rotational characteristics that contribute to foot motion. This will help you determine the plane from which the pathomechanics emanate. This, in turn, will help you judge the effectiveness of the proposed treatment. Multiple camera views are ideal. For instance, a side view of gait is one that we don’t often get to evaluate unless there is the ability to film it. This will let you see the function of the first ray and whether the hallux participates in propulsion. It will also allow you to see how much motion actually occurs in the first ray during gait. You can see overall posture from the side view. Other camera views that are helpful are those that zero in on the foot from the front and back. A camera view at head or shoulder height is also helpful. This will help you determine whether there is a leg length discrepancy, a pelvic tilt or even shoulder tilt. It is not uncommon to see hallux limitus occur asymmetrically in a patient who has scoliosis. Consider the situation in which the source of the asymmetry was the curvature in the back which, in turn, lead to a functional leg length discrepancy. If this goes undetected, then the surgical solution you plan for the foot may not be effective over the long term. However, if you have a more comprehensive picture of a person’s function, your surgical results may be even better if you integrate a biomechanical approach as well. These positional variations may be helpful in determining how the pathology has affected other parts of the body. Taking Video Views To The Next Level You should also consider having the patient use a treadmill. Using a treadmill to record close-ups from various angles around the person will allow you to key in on the region of interest. For instance, if there is concern about shoulder tilt, zeroing in on the upper body would be helpful. In order to gauge the affect of genu varum or valgum, you can focus on the patient’s legs. If you’re going to use a treadmill to help assess gait, you’ll need a dedicated area within the office. Sometimes setting up an arrangement with a facility that has one is an easy way to try it before determining whether it is worthwhile in your own practice. Scheduling a few patients in succession at a facility that has a treadmill can be cost- and space-effective. Taking it to the ultimate level is having a dedicated room for doing gait analysis. The room needs to be long enough to allow for a normal gait pattern and wide enough to accommodate side camera views. Therefore, the camera has to be far enough to away to see the entire body. This may seem like a large investment in space. However, if you believe in what you are doing, you will have positive returns many times over. How Can Pressure Mapping Help? While video recording of the foot going through its motions will give you a general outline or idea of what the foot is doing, pressure mapping fills in the necessary detail. Pressure mapping will allow you to see areas of high and low pressure during the stance phase of gait. This is the quickest and easiest information you can obtain from pressure mapping. Although this information may not be necessary for critical analysis in every patient population, there are those patients who only need this. Patients with peripheral neuropathy, for example, cannot give you the feedback you need when you’re constructing or working with a device or shoe modification. Assessing pressure distribution before and after treatment will give you concrete evidence regarding your treatment goals. It also allows the patient to see with his or her own eyes where the problem spots are and how you are addressing them. Pressure mapping also allows you to see the center of force and how it travels through the foot, how much force there is in comparison to the opposite foot, and the pattern of weightbearing distribution. Pressure mapping of the foot helps in painting a detailed picture of the foot. Using a combination of video and pressure mapping will allow you to do a comprehensive assessment of the stance phase of gait. This is the phase where most of the pathology occurs and the one where we have the greatest impact. What The Ink Mat Can Reveal The simplest form of pressure mapping is the ink mat. This was a popular technique many years ago that has since fallen out of favor with podiatrists. Certified pedorthists have revived it and use it on almost every patient they treat. It is an inexpensive and easy method that captures helpful information. Simply having the patient stand on it one foot at a time will yield the pressure distribution in a static position. You will be surprised what is revealed. For instance, something as simple as pain inferior to the second metatarsal head can show up as an area of intense pressure. Therefore, the treatment is already defined and your explanation to the patient is made a lot easier when he or she can actually see it. It is also useful in knowing where to add padding in order to accommodate pressure regions on the insole. With just a little bit of coordination, you might even get your patient to walk across it. This may not be a perfectly normal step, but it may be close enough to gain insight into which direction to go with the treatment. Can Software Programs Enhance Your Assessment Of The Patient? There are obviously more sophisticated ways to obtain this information. Various software programs can provide a wealth of data in the form of numbers, graphs and color distributions. However, using this technology without an understanding of foot function or without a defined purpose will not give you an advantage. Learning how to use it and what information it provides will allow you to apply it in specific situations where you need additional information. Indeed, measuring force throughout gait can be an excellent indicator for leg length discrepancies. Each and every day in our podiatric practices, we see an abundance of asymmetric findings such as bunions, hallux limitus or excessive pronation. Do you ever wonder why asymmetry occurs? In some cases, it may be a limb length discrepancy. Eyeballing the anterior superior illiac spine, feeling the crest of the ilia or even measuring legs may not provide you with enough firm evidence. With pressure mapping, you may be able to detect a consistent difference in force with each heel strike that may be the clue you need in determining whether an LLD is present. This may yield quantifiable evidence that is useful in guiding your treatment plan. Do you want proof that this works? Look no further than the success of patients who return with multiple shoes for modification. This, in turn, will open your practice to new populations of patients with other biomechanical complaints. Keep in mind that a biomechanical approach can help people with back pain of unknown etiology. It may be a matter of adding a simple lift in or on the shoe. We are in the advantageous position of being able to diagnose and treat a myriad of biomechanical conditions that are not limited to the foot. Employing pressure mapping of the foot also allows you to see the pattern of weightbearing distribution. You can assess how the weight is transferred through the foot during each step along with the timing with which it happens. This will give you important information regarding first ray function and whether adequate propulsion exists in a symmetrical fashion. If the first ray is dorsiflexing and there is excessive pronation occurring through midstance, the hallux may be causing propulsion to occur from the second metatarsal head and producing sub second pain. These are findings you would never see with video alone. The opposite is true as well. Just using pressure mapping alone will not allow you to see the rotational components to gait from structures proximal to the foot. There are a variety of graphs that can be extracted from the function of each foot. The numbers collected by themselves are not as important as the comparison you obtain between the two feet. The key to a good outcome is trying to restore as much symmetry as possible. You can compare this to a car. If the front end is not aligned properly, then the car will not drive smoothly. Restoring symmetry will restore the smooth ride. The same is true for our bodies. Restoring alignment is important not only in maintaining comfort, but in controlling the pathomechanical forces that we deal with in every step. Combining pressure mapping and video gait analysis will give you the information you need to try to restore symmetry and provide comfort. When Improved Diagnostic Views Facilitate More Effective Treatment Having a specific reason to assess gait will allow you to help diagnose and treat many biomechanical imbalances whether they are in the foot or are located more proximally. Few practitioners actually take the time to assess the whole person and even fewer practitioners have the interest in biomechanics to assess the dynamic function of their patients. Many biomechanical imbalances or asymmetries can be easily identified with extra knowledge and attention. Gait analysis is not a cure. It is just a test to help determine what the actual problems are and their point of origin. However, once you have obtained that information, then you can plan the best course of treatment, whether it is conservative or surgical. Assessing gait and analyzing motion gives you insight into how pathology occurs. It may also make you think harder about some of the surgical procedures that are routinely done. Addressing localized foot complaints may have a larger impact as other parts of the foot or even more proximal structures are forced into compensation for the changes that occur. For example, we’ve all seen patients who chronically complain of wearing the outside of their shoes down. They get an orthotic and it gets worse. Why? If you take the time to analyze what the foot, leg and thigh are actually doing during gait, you may rethink what you are actually doing with the orthotic. Posting in varus for a foot that chronically rolls over the side of the shoe doesn’t make sense when you see it with your own eyes. After seeing the person function, you will have a reason for doing what you are doing. It becomes common sense instead of esoteric biomechanics. Pressure mapping will take it even further. Looking at the pressure and force distribution will tell you where the majority of the pressure is located. This is extremely helpful in treating a neuropathic foot and can give you excellent feedback on the efficacy of the orthotic device used to reduce pressure. With pressure mapping, you will be able to tell definitively whether you have effectively offloaded the foot. Seeing the path and amount of pressure the foot absorbs is helpful in understanding its function. Assessing how much force is applied in a certain region, such as heel strike, can give you important information regarding leg length discrepancies (LLDs). For instance, if the heel strike is of consistently different force with each step, you can detect an LLD you couldn’t have seen otherwise. Certainly your eyes, palpation and measuring are nowhere near as sensitive as detecting force differences during gait. If you observe a difference, then the pressure mapping can either confirm or refute it. This also becomes important in improving outcomes. Making a pair of orthotic devices without taking into account the differences between feet and legs will not be as successful as when you can tailor the devices to what the patient really needs for each lower extremity. You may also see there are situations in which an orthotic is insufficient and more control is needed. Reviewing the recordings will give you insight into how shoes can be used to achieve even better control of the foot. By using wedges, relasting, external lateral counters and lifts, you can achieve improvement in the patient’s foot function. This is even true following bunion surgery. Affecting the first MTP joint will directly affect propulsion and first ray function. This can be seen with both pressure mapping and video analysis. There are situations in which the hallux will become less flexible or not even purchase the ground following bunion surgery. This combination of events can lead to other lower extremity complaints and even back pain. Documenting function may even give the reason you need to justify further surgery or even prove that there would be no additional benefit to it. Gait analysis can also be helpful for follow-up assessments. Obviously, there is no need to repeat it if the patient has improved, his or her symptoms have subsided and he or she is walking with less pain. However, in the recalcitrant cases or the more challenging ones, follow-up exams are useful. Final Thoughts Using gait analysis is an innovative way to help you achieve a complete biomechanical assessment. We have grown accustomed to the static chairside exam and a quick hallway walk to assess our patient’s function. Using the technology available, we can easily take this a step further. There are many reasons why gait analysis is advantageous to you, your practice and, most importantly, your patients. Using gait analysis will open your eyes wider and give you added insight that you hadn’t realized was available. It will separate you from other podiatrists with other interests. It will also open doors you never knew existed. There are large populations of patients that are ready and waiting to benefit from our expertise in biomechanical function. Using gait analysis will help you determine which tools are needed to control the entire environment in which the foot functions. These tools may include orthotic devices, shoes, shoe modifications or even surgery. While gait analysis itself is by no means a cure, it is an effective diagnostic test that will help you achieve the best possible outcome for your patients. Dr. Levine is the Director of Dr. Levine’s Podiatry and Footwear Center in Frederick, Md. CE Exam #107 Choose the single best response to each question listed below: 1. Pressure mapping of the foot is used for: a) measuring degrees of pronation b) determining degrees of ankle joint equinus c) determining patterns of weightbearing forces d) determining amount of tibial varum 2. Back pain … a) is always caused by a leg length discrepancy b) can be diagnosed with pressure mapping of the foot c) is related to a person’s gait d) can be helped with biomechanical intervention 3. Symmetry between feet … a) can be detected with pressure mapping b) is usually the goal of biomechanical treatment c) can be assessed with video recording of gait d) all of the above 4. Video recording of the foot … a) is best done with a close-up view of the foot b) never requires a side view of the foot c) is best done with a close-up view from the rear d) is best done with multiple views in order to assess gait 5. Combining video recording and pressure mapping of the foot … a) provides an excellent way to assess a patient’s function b) will help diagnose and treat biomechanical lower extremity problems c) is necessary to treat back pain d) all of the above e) a and b 6. In patients with diabetic neuropathy … a) pressure mapping is more useful than video recording b) pressure mapping will tell where an ulcer will form c) pressure mapping will determine the effectiveness of offloading d) offloading will make wound care less effective 7. Pressure mapping of the foot … a) can only be performed with computer software b) can help determine transverse plane contribution to pathomechanics c) can be performed with an easy inexpensive ink mat d) is better than video in assessing swing phase pathology 8. Gait analysis is useful for: a) assessing effectiveness of shoe modifications b) assessing effectiveness of surgical procedures c) assessing effectiveness of offloading d) assessing effectiveness of orthotic devices e) all of the above 9. All of the following statements are true about shoe modifications except: a) shoe modifications are an important tool in restoring symmetry b) shoe modifications include elevations, rocker soles and a variety of other creative ideas c) the effectiveness of shoe modifications can be assessed with gait analysis d) shoe modifications can only be done for orthopedic shoes 10. Why would you perform gait analysis? a) to help diagnose biomechanical imbalances b) to help determine why pressure ulcers form c) to help perform a thorough biomechanical examination d) all of the above Instructions for Submitting Exams Fill out the postage-paid card that appears on the following page or log on to www.podiatrytoday.com and respond electronically. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam. Responses will be accepted up to 12 months from the publication date.

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