Joint pain is the second most common complaint that people have when they visit a physician. Over 50 million individuals in the U.S. are afflicted, and approximately one-third of the population over age 45.  Joint pain results in over 40 million physician visits each year.  In addition, joint pain is the leading cause of disability in the U.S., affecting approximately 18% (8 million) of the adult population.  Direct and indirect costs of joint pain were estimated at over $65 billion in 1992 (Yelin, et al, 1992) and have grown considerably since that time.

Of the various joint pains, knee pain dominants, accounting for more than 14 million physician visits each year in the U.S.  In fact, knee pain is the third most common complaint of individuals seeking the advice of a physician (Table 1) (CDC 2009).

Table 1. Most common complaints of ambulatory care patients who are not seeing a physician for a regular physical, pregnancy check-up, or post-surgical follow-up.

When a patient with joint pain visits a physician they will usually be told they have a form of arthritis. Arthritis is a general term for a variety of joint diseases. There are three types of arthritis:  the most common by far is osteoarthritis, which is often referred to as ‘wear and tear’ arthritis, and is commonly thought to be a natural outcome of aging.  In addition, there are the more rare conditions of rheumatoid arthritis (an autoimmune disease), and ankylosing spondylitis (general associated with spinal pain, and is thought to be genetic in origin).

Most ambulatory care visits for arthritis involve persons over age 45 and over (75%) and predominantly women (66%).  Individuals with joint pain most commonly visit a primary care provider (52%), followed by orthopaedic surgeons (20%), and rheumatologists (17%).  The standard of care for patients who visit a physician is pharmacologic treatment (anti-inflammatories and pain medications).  In a recent study of 36.5 million physician visits for joint pain, over 70% of patients were given a total of 59 million drug prescriptions.  The most commonly administered drug was non-steroidal anti-inflammatory (NSAIDS), followed by analgesics (both topical, non-narcotic and narcotic), and corticosteroids (Hootman, et al 1997).

This standard approach to the treatment of arthritis is currently undergoing close scrutiny as it does not at all address the underlying cause of the pain. Rather, the pharmacologic approach simply allows the individual to mask the pain until joint degradation reaches a point where the knee has to be replaced (total knee arthroplasty – TKA).  Previously, it was believed that nothing else could be done, but studies such as the Arthritis Foundation’s “Arthritis Self-Management Study” have shown that simple preventative approaches, such as exercise, can be as effective as pharmacologic treatment (Lorig, et al, 1993).  Unfortunately, such approaches are severely underutilized.

The difficulty in pursuing preventative approaches to arthritis, and more specifically, exercise interventions, is that, historically, there has been no means for identifying the specific exercises which need to be undertaken by the individual to relieve the pain of arthritis.  As a result, a broad range of exercises have been provided to the individual, and after a short time, most individuals abandon their exercise routine, both because it is so time consuming, and since there is no feedback on whether progress was being made.

Yet, the basis for exercise intervention is well established. Since the beginning of the 20th century it has been recognized that specific muscle imbalances (either among complementary or agonist/antagonist muscle pairs) results in inappropriate distribution of forces in a joint, resulting in inflammation and eventually degradation (Truslow, 1909) – note that trauma and congenital defects can also lead to inappropriate joint loading, though these situations are far more rare.  Correspondingly, restoration of muscle balance corrects the joint loading, allowing the joint tissue to heal and the pain will disappear.

The challenge that has faced the healthcare community since the early 20th century has been one of identifying the specific muscle imbalances.  With the advent of electronic technology in the 1920 and 1930s, the technique of measuring the electrical potentials in contracting muscles (electromyography – EMG) began to be developed and it was widely hoped that this technology would permit accurate muscle assessment. EMG started to be utilized in the late 1960s, but EMG techniques could not be found which would permit comparisons between muscles or over time, and given the difficulty of application, was never widely accepted in the primary care clinic.  Integrated circuit technology developed in the 1980s did produce developments in EMG technology which allowed it effective use during neurosurgery.

In the 1970s and 1980s, feedback control muscle dynamometry was developed, and again, there was great hope that a means for assessing muscle activity would be available in the clinic. However, dynamometry requires that any exercise activity used in an assessment be open-chain so that the application to functional activity is unclear.  Moreover, muscle dynamometers report torque generated at a joint, rather than the activity of a specific muscles, so that direct application to a muscle training regimen was always indirect. The inability for muscle dynamometers to assess closed-chain activities resulted in insurance companies removing this assessment technique as a reimbursable evaluation, and their presence in clinics has been greatly reduced over the past decade.

Starting in the 1990s, a research group in Italy began to pursue the phenomenon of “muscle sound” as an alternative means for assessing the activity of specific muscles.  This research progressed from using microphones to record the sounds that muscles create when they contract, to small accelerometers to record the actual muscle body vibrations at the surface of the skin.  This new recording technique has been called mechano-myography (MMG) in order to distinguish the technique from EMG, but more accurately, the technique should be called vibromyography, or VMG, as it is the muscle vibrations on the surface of the skin which are being recorded.

Recent work out of the State University of New York at Binghamton, has shown that advanced signal processing techniques can be applied to a recorded VMG signal from a muscle undergoing contraction during a functional activity, resulting in a reflection of the absolute force being generated by the muscle.  This approach works for muscles in either isometric contraction or in isotonic contraction.  Moreover, the repeatability of the recording permits comparisons between different muscles, between different people, or comparisons in the change of a person’s muscles over time.  In other words, there now exists a convenient and reliable technique available for assessing muscle balance during closed-chain functional activity.

Arthritis has not attracted as much attention as other chronic health conditions such as diabetes, cancer and heart disease, perhaps because the associated rates of mortality and hospitalization are relatively low.  However, the burden of arthritis on individuals and society is extremely high.  Indeed, given the high prevalence of arthritis, the impact on the workplace, the healthcare system, and the quality of life for the affected population, the impact of joint pain is widely considered to be higher than that of other chronic diseases.   The goal of Sonostics Inc. is to provide communities throughout the U.S. (and perhaps eventually the world) with the resources necessary to indentify the specific muscle imbalances existing in individuals with joint pain as early as possible, and then help these individuals address their imbalances.  The company is starting with a focus on knee pain – evaluating both those with knee pain, and those who want to ensure that no muscle imbalance exists which could result in future knee pain and joint damage.  It is expected that there will then be progressive developments in the technology permitting additional joint assessments, such as elbow, hip, back and neck.  The development of VMG technology for the non-invasive assessment of muscle balance appears to be extensive, and the impact on the healthcare will be immense.

References
CDC. Summary health Statistics for U.S. Adults. National Health Inverview Survey 2009.

http://www.cdc.gov/nchs/fastats/docvisit.htm

Hootman JM, Helmick CG, Schappert SM. Magnitude and characteristics of arthritis and other rheumatic conditions on ambulatory medical care visits in the U.S.  Arthritis and Rheumatism 47:571-581, 2002.

Hurley MV, The role of muscle weakness in the pathogenesis of osteoarthritis. Rheum dis Clin North Am. 25:283-286, 1999.

Lorig KR,  Mazonson PD, Holman HR. Evidence suggesting that health education for self-management in patients with chronic arthritis has sustained health benefits while reducing health care costs.  Arthritis Rheum 36:439-446, 1993.

Turslow W. The principles of muscle balance as applied to orthopedic practice.  J. Bone and Joint Surgery, 1909.

Yelin E, Callahan LF for the National Arthritis Data Work Group. The economic cost and social and psyghological impact of musculoskeletal conditions. Arthritis Rheum 38:1351-1362, 1992.

The video shows how young athletes as well as older adults can discover if muscle imbalance is preventing them from functioning at top level and without pain.  This measurement device, which converts muscle vibrtion to absolute effort – totally non-invasively –  provides objective metrics of muscle performance heretofore impossible to capture.

You can see how far you have ridden and perhaps how many calories you have burned, or watts you have generated, or what your average revolutions per minute were – and from that information you may be able to derive what sort of progress you’re making while devoting those hours of blood, sweat and tears to improving your leg muscle efficiency and your cardiovascular condition.

What you don’t get, however, is insight as to how those muscles in your legs are interacting, how they contribute to the ride, the rate at which they fatigue, and perhaps how they respond to hydration or nutrition.

It was with that goal in mind that Tim and Sara decided to tackle the Keiser stationary bikes at the Island Health & Fitness Center in Ithaca, NY last week. They decided to ride at a fixed gear with reasonably high rate of resistance – 18 on the Keiser scale – maintaining a constant cadence (65-70 RPMs) for five minutes while they remained firmly in the saddle.  A later test will explore the difference in muscle contribution between saddle riding versus standing.

They strapped vibromyography sensors to their vastus lateralis and vastus medialis muscles on both legs to enable the MyoWave muscle assessment device to calculate the amplitude of effort generation throughout the ride.

MyoWave collects about 60 data points per second so the amount of data that had to be analyzed over that 5 minute period was rather substantial. MyoWave spent about 2 seconds generating a report after the ride was stopped. The results demonstrated that there is an opportunity to use MyoWave to analyze individual muscle contribution and muscle balance in a dynamic exercise over a protracted period of time.

Since bicycle riding causes muscles to exert a varying degree of effort as the leg spins through each cycle we focused on the overall average amplitude of muscle effort.  However, MyoWave does permit the user to zoom in on individual sections of the data so it would be possible to analyze each section of the stroke and consider the ratio of peak effort between Muscle A and Muscle B.

So what did this data tell us?

Tim’s dominant leg is his left. From the data, it appears that as the five minute test progressed, he relied more and more on only one muscle – the vastus medialis  – to carry the predominant load.  This was a surprise – we did not expect to see such single muscle dominance.

The left vastus lateralis, that had performed virtually equally from the outset, really diminished in effort as time passed and it seemed clear that an imbalance between the two medialis muscles was evident.

Sara, on the other hand, used both vastus lateralis muscles to carry the load and their output remained quite constant throughout the entire exercise. It would appear that fatigue showed, as evidenced by the decline in both of her vastus medialis muscle fiber contractions over time.  This is a distinct difference between VMG and electromyography, which counter-intuitively tends to show increased amplitude as muscles fatigue.

Bottom line – we learned that MyoWave can digest data from lengthy exercises which opens the tool up to be used in a broader range of activities.  For example, serious biking enthusiasts might learn a great deal about their performance and be able to tailor training regimens to their own specific muscle balance metrics. For racers, this will provide a wealth of data that can translate into valuable training edges.

Since we have architected the device to try to minimize the effect of impact spikes, one of our next experiments will be on the treadmill. Imagine evaluating running styles with different shoe types, body position, etc.  The world is now that much bigger.

The purpose of the database is to help establish both what “healthy” knee muscle behavior looks like, and correspondingly, the nature of knee muscle imbalance in those subjects who already complain of knee discomfort. One widely accepted factor in the etiology of osteoarthritis (OA) of the knee is the existence of knee muscle imbalances which can compromise the proper function of the knee joint, and over the course of many years lead to joint damage.

If we can identify the normal balance of flexor and extensor muscle activity of healthy knees during these activities, we will be well positioned to identify those individuals in whom muscle behavior is imbalanced.  Our goal is to help reduce the age-related onset of OA in those individuals with muscle imbalance at an early age, which would then permit early intervention (appropriate exercise) to correct the muscle imbalances.

These muscle assessments are being undertake using MyoWave, a remarkable device that converts muscle vibration to absolute effort via a technology called vibromyography (VMG).

Jonathan was one of the subjects who responded to our invitation to perform a simple “step-up” routine which we utilized in this database development project.

Jonathan is a previous college football player with numerous knee injuries in his youth, but was functioning well until the last year.

At the time of testing, Jonathan was struggling just to get up the stairs to the room where the evaluation was taking place but what transpired that day and over the following three weeks was quite inspiring and deepened our appreciation for the sometimes magical information this technology can provide.

Below is a video we did with him:

Bob “Kingpin” Eres developed ProSportsBroadcasting.Com and hosts interviews with companies describing new technology and Sonostics was selected to be the interview target this morning.

To support the interview about vibromyography in general and MyoWave in particular we took the opportunity to film a video in preparation that tested the flexors and extensors of Adam, one of our software architects, during a full golf swing. This seemed to be a useful experiment given the type of audience Bob gets on his website.

Here’s the video:

Not knowing what was under the hood, we spent weeks trying to reverse engineer the application, applying band-aid fixes and patches wherever we could.  However, as almost any programmer who has worked on somebody else’s antiquated code can tell you, this was no simple task.

MyoWave, a product designed to measure muscle activity and detect muscle imbalance, had taken many different twists and turns since its initial inception and as a result, the code reeked of disarray. There were single files thousands of lines long and any flow which may once have existed had long since vanished.

With looming deadlines only weeks away, we were faced with a choice.  Should we try to salvage the existing code base or should we toss it aside in favor of a totally new, untested approach?

In a larger company the bean counters surely would have told us that the risk was much too high, that we had invested too much to simply throw away something that “worked.”  Something, even something unpleasant, is always better than the unknown.  Or is it?

Throwing caution and conventional wisdom to the wind, we decided to attempt the unthinkable and started architecting a new application which would share the same MyoWave name, but be an entirely different application from the ground up.  Looking back one month later, I can say without a doubt that we made the right choice.

This is what we came up with.

We wanted the MyoWave application to be extremely elegant, simple, fast, and we wanted it to run on practically any platform we could conceive of with a minimal amount of rework.  We also wanted the MyoWave software to be as unique and revolutionary as the Vibromyography technology it supports.  The application architecture we came up with set out to do exactly that.

Most desktop applications rely on a desktop framework for handling UI elements… Aqua, GTK, Qt, Tk, and the list goes on and on.  However, none of those frameworks really works well across all platforms, especially once you get into the mobile space.  You might be able to snag a handful, but certainly not the whole group.  As a result, we decided to build our entire interface around HTML, CSS, and JavaScript (an approach similar to HP’s revolutionary webOS).  With HTML and CSS, we would have a limitless canvas on which to draw and to do whatever we pleased in a way no desktop framework could offer.

However, we still wanted this to be a desktop-only application which would not rely on any type of network connection or dedicated webserver.  As a result, we built a custom WebKit (.NET) “web browser” with APIs allowing for bidirectional communication between C# and the JavaScript running therein. In this way we were able to open files, communicate over USB, and accomplish other feats which would not normally be possible using JavaScript alone.

…but we still had a problem.

Vibromyography relies upon enormous computations which would not be feasible in Javascript – or any interpreted language for that matter.  C# might be able to keep up, but would force us to abandon our goal of a cross-platform existence.

As a result, we set out to write an entirely separate application in straight C which would be extremely fast, run natively on just about any platform, and handle all of the computations we required.  It would be controlled entirely by the master MyoWave app, and so, a simple command line interface would suffice.  The computational results would be output in a JSON string, communicated via stdout through the C# handler, and passed onto the javascript code where they would be displayed to the screen. The end result was as beautifully elegant as it was innovative.

The resulting application (written in one month’s time) is blazingly fast and sports a slick UI not easily possible in your run-of-the-mill C# or GTK app.  Additionally, by swapping out the few hundred lines of C# glue for some Objective-C (OS X/iOS) or Java (Android), MyoWave will be able to run on any platform which supports WebKit (which these days is pretty much everybody!).  Furthermore, if we decide one day to make the transition to SaaS (Software as a Service), our code reuse will be close to 100%.

I hope this example helps to serve as a testament to the notion that frequently throwing out software that “works” can allow something far greater to be born.  Just as a farmer prunes back the branches of an apple tree, so too should software developers cut out bad code so they can focus all their efforts on something which is simpler, cheaper, and better.

To find out the answer for two very commonly scrutinized muscles in the thigh we performed a semi-scientific test one recent afternoon.

We attached three vibromyography (VMG) sensors to the belly of the vastus medialis (VM) on Sara, our willing Sonostics subject, using elastic straps with a “quiet” hook-and-eye system. With much experience we had determined that Velcro straps simply make too much noise as the loops and hooks get stretched. Admittedly, we have not yet devoted any time to determining whether the frquency of that noise could be readily filtered out – a job for another afternoon.

The first sensor was affixed using an elastic strap about 3 inches above her knee.  A second sensor was attached about 2 ½ inches above the first and yet a third was attached a similar distance above the first two.

Sara then performed ten squats and we monitored the effort generated by the VM during each event.

We repeated the experiment, switching the sensors to her vastus lateralis (VL) and added a fourth sensor even higher than the first three.  To ascertain the level of repeatability we had her re-do the VL test, squatting an additional ten times.

The results were consistent and quite interesting and provided insight as to how we ought to advise users of this technology.  We found that the lower the position of the sensor on either the vastus medialis and vastus lateralis, the greater the effort recorded.

Given all the caveats about the lack of scientific method we used in this afternoon activity, there was no doubt that – in this test with this subject at least – total amplitude of muscle effort was reduced with each successively higher placed sensor.  The table below and the accompanying graph describe the correlation between distance from the knee and percentage of signal recorded:

We also compared the absolute total effort calculated by the lowest sensor on each of the VL tests (the one 3″ above the knee) and determined that the difference between the two sets of squats for that sensor was less than 4%.  Obviously, we need to expand this experiment to include other subjects as well as to repeat this with Sara but we decided to share the information nonetheless.

About 300 Athletic Directors from New York State attended and Sonostics certainly stood out as the only vendor with muscle assessment technology. Over the course of the two days we demonstrated the MyoWave device, with the help of two field hockey players from nearby Skidmore College.

One had suffered an ACL injury 5 years earlier and, although it was fully healed, we were gratified to see that the device picked up the fact she had learned to compensate for it. Muscle effort was obtained from the quadricep, bicep femoris and erector spinae, displayed as a graphical analysis of muscle balance ratio.

As I continue to train for my first full marathon and develop many of the common symptoms and pains experienced by long distance runners, I find myself looking more and more towards my $150 running shoe, designed to stabilize my feet as I run, alongside my $500 custom built orthotics designed to prevent over-pronation.

With at least two in three runners sidelined because of lower extremity pain such as patellofemoral syndrome (runner’s knee), a hotly debated subject in recent years has been the proficiency of the athletic shoe. Marketed to prevent and treat such injuries are a wide array of choices such as motion control, stability, gel cushioning and arch support, however in recent years both kinesiologists and orthopaedic doctors have debated whether they actually prevent or cause injuries in the lower legs. A recent article published in the New York Times suggests orthotics are not only impossible to fit correctly, they can actually make the muscles work up to 50% harder. So mile after mile on my long Sunday run, I ask myself – do my running shoes and orthotics actually have an impact on my muscle effort and are they possibly causing my injuries?

I also ran across a fascinating TEDTalk by Christopher McDougall about the barefoot ultra-marathoning Tarahumara from Mexico, for whom running injuries are rare.

Fortunately, because of the work that I do, I was able to put this theory to the test. By using vibromyography (VMG) as an objective assessment of knee muscle balance, I designed an experiment that would test the differences (if any) in my footwear.

Single VMG sensors were attached to my vastus lateralis, biceps femoris and the sartorius muscles using an elastic strap.  I then performed 6 one-legged squats with inward rotation of the knee while wearing inexpensive running shoes. The graph displays the averaged level of effort expended during the 6 repetitions. The red line represents the Sartorius; the blue the Vastus Lateralis.

I then repeated the exercises wearing motion control stability footwear:

and then a third time with orthotics in those expensive running shoes.

Lastly, I repeated the exercises while barefoot.

Upon completion of each set, the amplitude of effort generated simultaneously during the exercise by all three muscles was compared.

If the goal is to strive for muscle balance we can see from the experiment that both barefoot and running shoes with motion control and orthotics appear to deliver the best results. Notably, the muscle effort was least balanced with inexpensive running shoes and only slightly better when the motion control footwear without orthotics was worn. In addition, all shoe wearing results showed that the sartorius worked at least 40% harder than it did during the barefoot exercise.

So, in concurrence with claims by orthopaedic doctors and kinesiologists, vibromyography suggested to me that my footwear of choice doesn’t in fact control my motion nor does it correct my over-pronation (although notably it does not negatively impact it as has been suggested in other articles). There is, in fact, no difference, at least for me, between wearing my extremely expensive running shoes with my very expensive custom-built orthotics and going barefoot, despite the claims of the overly helpful sports store manager!  Maybe the Tarahumara are on to something.

Once injured, the prevalence of recurrence is much higher.

In the video below, Christie Rampone, U.S. National Team Soccer player recounts her experiences with ACL injuries and subsequent rehab.

watch?v=T-Hdms639FQ