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What is the Rotator Cuff?

The rotator cuff (often times mispronounced as the rotator cup) consists of four muscles which hold the ball of the shoulder (a.k.a. humeral head) into the socket (a.k.a. glenoid). The four muscles can be remembered by the acronym “SITS.” They stand for Supraspinatus, Infraspinatus, Teres Minor and Subscapularis. Each muscle is responsible for a select motion. They are as follows:

  • Supraspinatus- abduction (a.k.a. elevation of the arm)
  • Infraspinatus- external rotation (a.k.a. rolling the arm outward)
  • Teres Minor- external rotation (a.k.a. rolling the arm outward)
  • Subscapularis- internal rotation (a.k.a. rolling though arm inward)

Rotator Cuff Lateral ViewRotator Cuff-Joint Capsule

Collectively, these muscles and their tendons work together by surrounding the ballphony anatomy shoulder joint (head of the humerus) and, with tension, help seat the ball into the socket (glenoid).
Since your ball is three times the size of your socket, the rotator cuff requires a lot of help in holding the joint together. There are two other structures which are instrumental in holding the ball into the socket (a.k.a. glenohumeral joint). The first structure is called your glenoid Suction Cuplabrum. The glenoid labrum attaches the larger ball to the smaller socket and acts like a suction cup (like the end of a toy dart) in order to hold the two together. In fact, the labrum is of similar makeup as the aforementioned suction cup. It
has a rubbery-like texture. The second structure is the joint capsule. The joint capsule is a stiff fibrous membrane composed of avascular tissue (no blood flow) which envelops the shoulder joint (glenohumeral joint) and assists the rotator cuff and the labrum in holding the ball into the socket. Since the shoulder joint (glenohumeral joint) is classified as a synovial joint (a joint that holds fluid), the joint capsule helps hold the synovium (a viscous fluid) in and around the joint for lubrication. Any one of the four rotator cuff muscles, the labrum or the joint capsule can be acutely injured (traumatic) or chronically injured (happens over time, normal wear and tear). Regardless of the mechanism of injury (MOI), acute or chronic, they are classified as a Grade I (1/3 tear), Grade II (2/3 tear) or a Grade III (full-thickness tear). The treatment, whether conservative (physical therapy) or aggressive (surgery), depends upon the Grade, location and number of structures torn.

Dr. Brett Purdom, PT, DPT, ATC, CSCS
Owner of The Foot Mechanic™
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What does Tendinitis mean?

Tendinitis literally means inflammation of the tendon. In fact, any time you see the suffix “-itis” behind a name of a body part it means inflammation of that body part. As an example, inflammation of the Larynx is called laryngitis. But let’s get back to the causality of tendinitis. Every tissue in the body is formed on what is called a “collagen matrix.” In fact, we can consider collagen as the building blocks of all tissue. Each tissue has varying amounts of collagen. Collagen is in its highest concentration based on the stiffness of that tissue (or, it’s resistance to injury). The collagen matrix concentration in the Skeletal-Muscle System in order is; bone, ligament, tendon and finally muscle. Further, the collagen fibers are uniquely positioned such that they are aligned in positions which offer the greatest resistance to the forces under which that tissue must absorb. As an example, jumping off the tailgate of a truck will not fracture the bones in your leg. However, if the same force hits your thigh bone (femur) directly from the side, it will immediately fracture. This is due to the directional nature of the collagen matrix. In the femur, the matrix is set up only to absorb forces that transfer the length of the bone. It is also important that you understand blood flow in these tissues. Blood flow is inversely proportional to the amount of collagen a tissue contains. Muscle has the greatest amount of blood flow and the lowest concentration of collagen, while bone has the least amount of blood flow in the highest concentrations of collagen. When put under a microscope muscle fibers appear red and bone fibers appear white. When put under a microscope, a tendon will also appear white. This means its blood flow is relatively low. When a tendon is stressed in a manner which goes against its collagen alignment, an injury can occur. This injury will cause micro tearing of the tissue and bleeding. This is why we call it “tendinitis.”Achilles tendinitis JPEG Over time, and as the tendinitis continues to go untreated, the micro tearing can increase in size rendering the tendon too painful to use. Couple this with the fact that a tendon has relatively low blood flow, it is clear why a tendon will take longer to heal. Muscle, because it has a greater amount of blood flow typically takes about 2 to 4 weeks to heal. Tendons usually take 4 to 6 weeks to heal. Ligaments typically take 6 to 8 weeks to heal. And this is why when you have a fracture, you are casted for 8 weeks. Bone has the least amount of blood flow.

Treatment: if you feel it tendinitis coming on or, have been diagnosed with the tendinitis, here is the treatment protocol:

  1. Follow the principles of RICE (Rest, Ice, Compression, and Elevation) for the first 24-48 hours
  2. 0-2 weeks, stretching and isometric exercise, alternate heat and ice
  3. 2-4 weeks, stretching, light warm-up (exercise bike), strengthening exercises at 25-50% PME in the same alignment of the collagen matrix, stretch and ice after
  4. 4-6 weeks, stretching, moderate warm-up (exercise bike/treadmill/elliptical/fast walking), strengthening exercises at 50-75% PME in the same alignment of the collagen matrix, do not exercise through pain, stretch and ice after
  5. 6 + weeks, reintegration of normal exercise routine, do not exercise through pain, stretch and ice after.

Dr. Brett Purdom, PT, DPT, ATC, CSCS
Owner of The Foot Mechanic™

What is an Overuse Injury?

An overuse injury is any repetitive movement whose force requirement exceeds that which a muscle and/or its tendon (a.k.a. muscle-tendon complex) are able to sustain over a given amount of time. The result is tearing of either the muscle or tendons’ fibers. When this occurs there is a small amount of bleeding. In this case, bleeding is advantageous as it will bring in all of the healing constituents necessary to repair the tear. Here, the old adage RICE (Rest, Ice, Compression, Elevation) applies. The underlying problem is most will “chalk” this up as a minor setback. They will not treat it appropriately and will continue to perform the repetitive movement while tolerating the minor pain. Here is where the problem exists: there are 3 stages to injury. The 1st phase is the acute phase. The acute phase is the 1st 24 to 48 hours. It is no coincidence that this is the timeperiod where icing an overuse injury is often recommended. It is in this acute phase where this injury is most easily treated. The 2nd phase is called subacute phase and it is from 48-72 hours. It is generally advocated that during this phase of treatment a person should alternate heat and ice while doing light stretching exercises. If left untreated, during this timeperiod the blood flow to the injured area begins to stagnate and become nonfunctional. An overuse injury is much more difficult to treat during this phase. From 72 hours-on an overuse injury enters its chronic phase. In this phase, the injury must be brought back to the acute phase in order to be treated. This is usually done in physical therapy with the use of physical therapy modalities such as cross-friction massage, ultrasound, electrical stimulation (E-Stim) and/or provoking exercises. Too many times overuse injuries are allowed to enter the chronic phase. Over time and as the overuse injury continues to go untreated, it can increase in size rendering the muscle-tendon complex too painful to use. Continuing, muscle-tendon tearing worsens and can eventually lead to rupture. In summary, overuse injuries are very common in the recreational athlete. If treated immediately using the principles of RICE, these such injuries can be cleared up in a short period of 2 weeks. If left untreated over weeks of repetitive motion, a person might need a minimum 30 days of physical therapy at a frequency of 2 × per week. If longer periods of overuse occur (1+ months), surgical intervention might be the only option.

Dr. Brett Purdom, PT, DPT, ATC, CSCS
Owner of The Foot Mechanic™

Barefoot/Minimalist Running Debunked

Barefoot and minimalist running styles are dangerous for your feet. In fact, they fail to recognize the most primitive biomechanics of running or the deleterious effects of this type of running style on the human foot. Simply stated, longitudinal studies outline the foot must start in a rigid position (closed-packed or supinated) position. It then must transition into a malleable (loose-packed or pronated) position in order to adapt to the ground surface. Finally, its 3rd phase is to re-transition into a rigid (closed-packed or supinated) position in order to gain a rigid lever for push off. The 26 bones in the foot are intimately and precisely positioned to go through these phases (heel strike, mid stance and push-off) in order to prevent injury. By altering the mechanics of walking/running by using toe-running or midfoot striking a person sets themselves up to what we call “retro loading” which puts extreme non-biomechanical forces across the bones of the midfoot (tarsal bones). This can cause, but is not limited to, acute pain, plantar fasciitis, early arthritic changes, stress reactions and even stress fractures. This doesn’t even mention the adverse effects which may occur up what we call the kinetic chain (ankle, shin, knee, hip and low back). The evolution of the human running shoe is not a manifestation of the shoe companies’ attempt to sell more shoes. Rather, the running shoe is a product of evolution based on longitudinal studies of human biomechanics. If they were not we would all still be running barefoot. It seems that this whole “barefoot” running craze/phase is attempting to de-evolve the human foot back centuries. The only reason there are so many advocates for this type of running style is the mere fact that it is so relatively new we do not yet have longer-term longitudinal studies proving the aforementioned osteoarthritic/stress reaction/stress fracture data. However, if you browse around the Internet you will certainly find anecdotal testimonials as to such. I would refer you to the following two articles:

Barefoot Running Problems – Men’s Health

Dr. Brett Purdom, PT, DPT, ATC, CSCS
Owner of The Foot Mechanic™

When Should I Replace my Orthotics?

When should you replace your orthotics? Not to answer a question with a question but, why do you think they need replacing? The Foot Mechanic’s™ orthotics are milled out of a highly durable sheet of polypropylene. I jokingly tell our clients that, “they will find your orthotics in a landfill long past when we are gone!” The reason I say this is because the orthotic itself, meaning the polypropylene shell, will not lose its integrity. However, if it is only a matter of the top-cover breaking down, this is a very easy fix. We would need to take your orthotics in and simply replace that top cover.

If it is a function of the bottom wearing down, this can alter the biomechanical function of your orthotics. The question then becomes “why” is this occurring? More so, if you are experiencing a recurrence of your original symptoms or experiencing different areas of pain, it might be time for a reevaluation.

Typically, The Foot Mechanic™ advocates its’ clients be re-evaluated about every three years. This is not because the orthotic will break down, but rather your feet will change over time. Although you might have worn orthotics religiously, your foot structure and function will continue to break down as a function of time, pressure and volume of every step you have taken over that time span. The Foot Mechanic™ saves all of your evaluation data in a database so we may compare your old data to that which we obtain during your re-evaluation. If there is a significant enough difference, The Foot Mechanic™ will make you a replacement set(s) of orthotics at a “returning client” discount.

Dr. Brett Purdom, DPT, ATC, CSCS
The Foot Mechanic™

The most common overuse injuries in running and how to protect yourself from them: Plantar Fascitis

As you begin ramping up your running in preparation for an upcoming race, triathlon or just general fitness, it is also the season for overuse injuries. One such injury is plantar fasciitis. Plantar fasciitis results from the breakdown of your arch which stretches a tissue called the Long Plantar Ligament. Unfortunately, this ligament is not elastic and therefore does not stretch. Rather, this tissue undergoes micro-tearing. "Bow-string affect" causing Plantar FasciitisSymptoms can reveal themselves as general arch pain, bottom of the heel pain or a gradual achiness which does not go away. If the first step out of bed in the morning elicits extreme pain, you more than likely have plantar fasciitis. Regardless, it is extremely important that you address these symptoms sooner, rather than later. The general rule: it will take twice as long for these types of injuries to heal as from the time you first experience symptoms until the time you first start your treatment. Rest, ice, gentle stretching and a break from training are your early treatment interventions. If, in your opinion, you have excessive arch breakdown (a.k.a pronation), a treadmill evaluation (biomechanical exam) can be done by The Foot Mechanic™. In many cases, an orthotic can be the answer. An orthotic is a device that replaces the liner in the bottom of your shoe and re-creates your arch, thereby returning your foot back to its “normal” mechanics. When choosing the proper orthotic, it is important to avoid over-the-counter (a.ka. retail) products as they are not custom to your feet.

Dr. Brett Purdom, DPT, ATC, CSCS
The Foot Mechanic™

Low Back Pain- Mechanical

 “Low Back Pain,” is a catch-all term used to describe general pain in what we know as pain in your lower back region or, otherwise known as your lumbar region. Many different diagnoses can cause such low back of which Is straining one or many of your low back muscles. This occurs in instances where you my reach into the back of your car to retrieve a sack of groceries. Simply, you strain one or more of the muscles in your back, much the same as straining a hamstring while you’re running. Generally speaking, when you irritate the muscle, you irritate its associated nerve, or visa versa. This pain generally subsides if you protect the muscles from any motion which causes one of them to work excessively hard. This can be very difficult as these muscles are also what we call “stabilizers.” A stabilizing muscle is  one which works all the time maintaining postural alignment in the upright situations. In this case, those lumbar muscles work to keep the spine in upright positions. This type of strain  is best treated with rest, icing and anti-inflammatory medication. Lite stretching is advocated after 24 hours after injury. Once you are pain free for a week, slow reintegration into activity and exercise is allowed. To learn more about this type of injury, click on the following link:  Low Back Pain

                                                                – Dr. Brett Purdom, DPT, ATC, CSCS
                                                                               The Foot Mechanic™

Plantar Fasciitis

Many people have heard the term plantar fasciitis yet are unsure as to what it really means. Simply put, the plantar fascia is the tissue on the bottom of the foot which connects your heel bone to the very front of the t toe bones and their associated tissues.The best analogy would be to take a bow and arrow and place the bow with the string side down on the ground. The bow would represent the arch of your foot while the string would represent your plantar fascia. Now imagine if you push the bow down, the ends would elongate and the string would stretch. Such is the relationship of the arch of your foot and the plantar fascia. However, as the string of a bow is very elastic, the plantar fascia is quite the opposite. It is a very stiff ligamentous-type tissue which resists all stretching. The result of the arch flattening with every step you take is continued stretching of the plantar fascia Over time, this “micro-trauma” to the plantar fascia results in inflammation, pain, tissue tearing and potential rupture.

                                                           – Dr. Brett Purdom, PT, DPT, ATC, CSCS
                                                              The Foot Mechanic™

to read more about this topic or other of Dr. Purdom’s blogs, visit his website at

Deconstructing ‘Five-Finger Running’ From an Injury Standpoint

The latest craze in running is Vibram’s new “Five-Finger” types of shoe ware. Although these products may be appropriate for a very select subset of the running population, the recent explosion of hype regarding this new craze has exposed many runners to a significant risk of injury . The premise of this style of running is that it will make the muscles around the lower leg and foot strengthen, subsequently restoring the runner’s function back to its evolutionary pre-shoe “normal state.” The untested theory behind this new fad can lead to two very serious problems. First, it requires the runner to adopt a new midfoot striking running pattern. Ninety-eight percent of all runners are heel-strikers. Without the proper coaching into how to transform from a heel-striking pattern to a midfoot striking pattern, the runner is left in the dark concerning this crucial modification. In fact, Ross Tucker, PhD “The Runner’s Body has found that 83% of all runners who make the switch to Vibrams continue their heel-strike pattern. Dr. Tucker’s research has concluded that since there is no cushioning in the Five-Finger shoe ware, heel pressures are seven times greater than running in a normal running shoe, markedly increasing the chance of injury. Here is the second problem of Vibram’s theory: Muscles and tendons by definition are meant to create motion across joints. Ligaments on the other hand, are meant to connect bones together and are responsible for giving the body structural integrity. In the foot they are responsible for holding your arch in a high position. When a person over pronates, the ligaments fail to do their job. Five-Finger systems would have you attempt to train muscles to do the ligaments job. This creates abnormal stress on the muscle/tendon unit and leads to inflammation, pain and eventual loss of function. This breakdown, in its early stages will present as small areas of inflammation and minor tendinitis. If left untreated, it can proceed into chronic tendinitis (which is much harder to treat), plantar fasciitis, Achilles tendinitis and other problems of the ankle, shin, knee, hip and low back pain. Additionally, all the muscles throughout this “kinetic chain” may be forced into performing stabilizing work which is not their primary function. This too may lead to overuse injuries which are not directly associated with the movement dysfunction down the kinetic chain.

As Running Events Increase in Number, So Do Overuse Injuries

As the number of available running events are on the rise, so too are those overuse injuriesassociated with increased training volumes. In fact, in a study published by Dr .D. Cosca, MD,University of California Davis Sports Medicine Program (Common problems in endurance athletes), he finds that “… intensive training and inadequate recovery leads to the breakdown in tissues reparative mechanisms and eventually to overuse injuries.” The real problem is the creation of the condition called “tendinosis.” Normal “tendinitis” is a common injury condition which, if treated correctly, leads to a healing response and ultimate restoration of that tissues integrity. Tendinosis, on the other hand, is a function of inadequate resting of a tendinitis. If the injured tissue is not allowed to go through its normal healing process, it enters into a vicious cycle of repeated micro trauma while disallowing the reparative properties of its blood supply. As the degenerative properties of the tissue progresses, it becomes more difficult to treat. The finality of this deleterious process may ultimately lead to tissue rupture. Major areas of diagnostic concern are plantar fasciitis, Achilles tendinitis, medial tibial stress syndrome, patellofemoral syndrome, iliotibial band friction syndrome, stress reactions, stress fractures, and other problems up the kinetic chain. The best way to prevent one of these injuries from limiting your training is to attack it early. Early intervention includes following the acronym “RICE:” Rest, Ice, Compression and Elevation. Unfortunately, it is ingrained in the marathoner’s mindset to ignore early symptoms and power through their regimented training programs. What he or she fails to recognize is that losing 1-2 weeks of their training programs is better than the alternative- losing 1-2 months. By following the correct treatment regimen, a visit to the local physician or physical therapist would be the next step. A custom biomechanical assessment and even custom foot orthotics may be appropriate, depending on such factors as over-pronation, leg length discrepancies or muscle imbalances.