The New Soldier: Physical Therapy Treatment for Veterans Returning from Iraq and Afghanistan

Physical Therapy started as a profession in the United States in the early 1900’s. It formed its roots at the beginning of World War II with advent of polio and the return of injured soldiers from Europe. As a profession, physical therapy has always been closely associated with the treatment and continued care of soldiers, helping them to return to their stateside lives or back to the battlefield.

As time has passed, both war and physical therapy methods have changed. With the enhancements in body armor, improvement in battlefield surgical care, and refinement in hospital care after primary on-site surgical interventions, soldiers are now surviving injuries that were previously fatal. This, along with the preciseness of new weapons, creates new physical and mental obstacles for both the soldiers and physical therapists to overcome. Among some of the most common is an increasing number of troops returning with traumatic brain injuries.

According to many studies, between 10 and 25 percent of all soldiers deployed to Afghanistan and Iraq are coming back with mild traumatic brain injuries. Symptoms include but aren’t limited to:

•Headaches or neck pain that do not go away;
•Difficulty remembering, concentrating, or making decisions;
•Slowness in thinking, speaking, acting, or reading;
•Getting lost or easily confused;
•Feeling tired all of the time, having no energy or motivation;
•Mood changes (feeling sad or angry for no reason);
•Changes in sleep patterns (sleeping a lot more or having a hard time sleeping);
•Light-headedness, dizziness, or loss of balance;
•Urge to vomit (nausea);
•Increased sensitivity to lights, sounds, or distractions;
•Blurred vision or eyes that tire easily;
•Loss of sense of smell or taste; and
•Ringing in the ears. (Centers for Disease Control and Prevention)
With the litany of common symptoms, physical therapists and injured soldiers alike are faced with the daily challenges of figuring out how to overcome their injuries and what methods of treatments would be most beneficial. According to an article published by the APTA, US Army Captain and APTA member Matthew R. Scherer, PT, MPT, NCS states that, ”there is limited scientific and medical literature available about the management of orthopedic, integumentary, neurocognitive, and neurobehavioral effects in survivors of blast, there is even less research addressing the vestibular symptoms of these injuries.” Because there is not significant research on “best practice” for these patients, we must tailor the therapy to address the specific need of each soldier. Using such techniques as word association (to increase retention), balance rehabilitation, and careful planning with the soldiers’ medical team is imperative to create a successful and amicable environment that promotes the best rehabilitation possible.

For more information about traumatic brain injuries in soldiers returning from the battlefield visit the Defense and Veterans Brain Injury Center’s website.

Picture from the Huffington Post.


Ryan Orser

What is the Difference Between Physical Therapists and Chiropractors?

While this seemingly simple question is commonly asked by patients, the resultant practitioner response is not often as simple. If I had a dollar for every time I have been asked this, I could retire today. First and foremost, each individual practitioner in each profession treats in his own unique way. This article will endeavour to enlighten you on the basic principles of difference between the two professions and shall provide a generalised overview.

Chiropractors diagnose, treat and prevent mechanical disorders of the musculoskeletal system, namely the spine. Their belief is that these disorders affect the nervous system and therefore one’s general health.

Physical therapy aims to maintain restore, maximise and develop one’s functional ability throughout life. Physical therapists are experts in rehabilitation and preventative therapy. It is a holistic approach to treatment that focuses not only on the physical, but the psychological, social and emotional well being of the individual through diagnosis, treatment and intervention.

Chiropractic treatment is concerned with vertebral subluxations of the spine. Treatment mainly involves spinal manipulation but can also include soft tissue therapy, electrotherapeutic modalities, exercises and health and lifestyle advice.

Physical therapy treatment involves mobilisations of joints, soft tissue massage, stretching, neuromuscular re-education, electrotherapeutic modalities and a large focus on rehabilitative exercises and a home exercise program.

Chiropractors practice autonomously and their service combines aspects from both alternative and mainstream medicine. It remains competitive with mainstream medicine and is therefore considered more of a complementary or alternative medicine.

Physical therapists on the other hand practice in numerous different settings such as outpatient clinics, inpatient rehabilitation facilities, extended care facilities, skilled nursing facilities, hospices, education and research centres, schools, occupational environments, fitness centres and private homes. Physical therapy has many specialities, the most common of which include orthopaedics, cardiopulmonary, neurologic, geriatrics and paediatrics.

Physical therapists work alongside and cooperate with mainstream medicine, largely due to the fact it is an evidence based profession that relies heavily on scientific research.

Hopefully this has provided you with a broad understanding of the fundamental differences between Chiropractors and physical therapists and has equipped you well enough to answer the notorious question.

Carla DiMattina

Wii-hab Increasing Rehab Potential

Lately, I’ve been reading many articles about the use of Nintendo’s Wii Fit as part of the rehabilitation process in many hospitals and outpatient clinics alike. We have been using the Wii Fit in the clinic where I work as a physical therapy aide for one year. We’ve found that it not only makes physical therapy sessions and the rehabilitation more fun, but has also improved our patients’ proprioception and balance as well.

Some therapists, however, are refuting the use of the Wii in a rehab setting as beneficial to patients. Eric Robertson, author of the blog site NPA think tank, thinks that the use of the Wii has potential to be harmful not only to the patients, but to the reputation of physical therapists (the blog can be found on this page (scroll down)). As a student of physical therapy, it is my belief that the Wii can be used successfully as a tool to enhance each patient’s treatment sessions. Robertson claims that since physical therapy is moving toward the doctoring profession, that therapist should be using their hands and doctorate education to make patients better. I would agree however; why can’t physical therapist use their knowledge of the body in conjunction with a tool that, not only makes therapy sessions interactive and fun, but gives therapists instant feedback as to where patients are shifting their weight? When is the last time someone was able to tell what percentage of a patient’s body weight was on the right leg versus the left just by looking at them? Not only is the Wii Fit a good biofeedback tool for patients to visualize their weight shifting, but with our doctoring and professional guiding hands, we can make PT more fun.

Even though some therapists disagree with the use of the Wii in a rehab setting, there have been a few studies that have shown improvements with peoples’ symptoms of Parkinson’s. Dr. Herz, an assistant professor of occupational therapy in the School of Allied Health Sciences and a study principal investigator along with Dr. John Morgan, neurologist, have found that using the Wii as a source of supplemental therapy leads “to physical, cognitive, psychological, and social aspects that address skills necessary to maintain independence and mobility in individuals with Parkinson’s disease.” (Parkinsons.org)

With the success of these kinds of studies (such as Decker et el from Rutgers University), other preliminary studies have started with positive outcomes showing the use of the Wii as a low cost rehabilitation tool. If physical therapists can make treatment sessions more fun while applying their doctorate knowledge of the body to make their patients better, then I think we should apply any means we can to make each patient happy and healthy.

For more current info on wiihabilitation, please visit http://www.wiihabilitation.org/

Ryan Orser

Snow Still Here

This year we have been blessed with a warmer-than-usual fall. Last week I was walking around in a t-shirt and jeans, while many of the central park joggers are still wearing shorts. As the next few weeks fall upon us however, the snow will eventually start falling. Only the hardcore runners will hit the upper loop of central park and the cyclers will start their indoor training. Ahhh the exchange of fresh air and the ever changing scenery of central park for the corner of your already cramped bedroom.

It is important for you cyclers to take this time to fine-tune your “fit” to the bike. The exchange of indoor for outdoor training provides you with the perfect chance to change and refine your positioning to optimize both your comfort, and your efficiency.

There are many different ways to measure your exact fit (25-30 degree flexion of the knee when the pedal is at the bottom most point. The distance from the top of the seat to the center of the bottom bracket is your inseam in centimeters multiplied by 0.883). Here are some basic things to look for when adjusting your bike’s fit:

1) Your hips should not rock back and forth when you pedal. Look for a position of the seat height where you hips stay level while you pedal.

2) Make sure your seat positioning isn’t too far forward or backward. With the pedal at 3 o’clock, make sure the most forward point of your knee is right over the ball of your foot and the axle of the pedal (use a plumb line)

3) If you use cleats, make sure that your cleats don’t make your feet too internally rotated (pointing toward the frame of the bike)

Remember, not everyone is symmetrical. For leg length discrepancies see your local physical therapist or orthotist for proper adjustment suggestions to your shoes. For everyone else, remember these three things while making your adjustments to the bike.

For expert fittings in NYC check out Signature Cycles.

Ryan Orser

"Jump" Back into Running!

Injured runners are often very eager to return to running as soon as possible. At times, it is very hard for me, as both a physical therapist and a runner, not to get caught up in their enthusiasm to get “back out on the road” quickly. My job as their therapist, however, is to make sure I get them back to running safely, without a greater risk for re-injury. One important phase that often gets overlooked when progressing their rehab program is the introduction of jumping/plyometrics. During one mile of running, your foot contacts the ground ~ 750 times! The deceleratory flexion that occurs during the landing phase of jumping/hopping is equivalent to the early stance phase in running. Therefore, one way to give the runner and the therapist confidence that they are ready to return to running is to put them through a series of jumping/plyometric drills. By practicing jumping/hopping skills before hitting the treadmill, both therapist AND patient can observe and practice technique to ensure that proper alignment and control is being maintained when the foot hits the ground ( i.e. the femur isn’t adducting and internally rotating excessively or knee falling into a valgus position). If their body can handle 750 jumps/hops (and they are able to maintain their form throughout), then, in theory, it should be prepared to handle one mile of running.

The Brigham and Women’s Hospital, Inc. Department of Rehabilitation, has developed their own return to running protocol.

I have found that putting my patients through their Phase II: Plyometric Routine has been a good way for me to critique their form, test their body’s tolerance to high impact and then determine whether or not they are ready to begin a return to running program. It has also benefitted as a tool to gauge cardiovascular endurance and to serve as a HEP.

Krista Simon

The Overhead Athlete

With spring training hopefully right around the corner and winter strength and conditioning programs in full swing it is important to have some information with regards to the overhead athlete and some quick pointers in identifying possible small problems before they become larger pathologies
1. Take your time in the pre-season: Many players will jump right back into a similar training regiment as they had been participating with at the end of the prior season. As with any muscles if you don’t use it you will loose it so realize that the new baseline for activity is dramatically different. With training there are 3 variables which include: Frequency, Duration, and Intensity and your body is good at adapting to a 10% change to ONE of these variables. Very simply put – don’t go from throwing for ten minutes to fifteen minutes & 50 to 100 feet in the same session
2. Your follow through is the most important part of throwing: Our bodies are at a biomechanical advantage to have greater force into internal rotation (one of the motions for throwing) than it is to produce force with the external rotators (the muscle group to decelerate the arm after the ball is released). A player can decrease the amount of stress placed on these smaller muscles by giving them a longer period of time to slow the arm by having an adequate follow through. In the non-throwing population typical range of motion for the shoulder is 180 degrees with overhead activities (flexion and abduction) Internal rotation 0~80 deg (depending on which medical association you reference) and External rotation of 0-90. Current research suggests that it is not uncommon to find a decrease in passive Internal rotation in throwing athletes and a decrease in the force production (in particular the “eccentric” or contraction while lengthening) of the External Rotators of the shoulder.
3. Ask for help early and often: In many instances our body will first ask us to stop an activity, then tell us to stop an activity, and finally make us stop an activity. Be aware of the early signs of problems which will include but are not limited to: pain, decreased force production, decreased ability to recover, and unintentional adjustments in mechanics. The human body in general will take a “path of least resistance” which will, unfortunately, cause bad habits to be further reinforced.
Health care and physical education is now leaning towards prevention, as it should be, with the focus on avoidance of injury as the primary focus. Before starting a season or sport it is necessary to have the proper coaching and advice in order to critique form and personal function. Experts in this area are, but not limited to: physical therapists, athletic trainers, Certified strength and conditioning specialists, and PE teachers. A team approach must be taken for every athlete and the participant has to be patient when working with a health care professional due to the necessity to build a good foundation first in order to have the ability to perform higher level tasks
In closing – it is important to have the proper preseason workout and have the proper support system to ensure good habits early on in the season and early in an athletes career. Athletes need to know when to ask for help and where to look for it throughout the entire process from the first toss to the final out of the championship. Patience is a quality that many lack but is absolutely necessary for a long career in a sport such as baseball where physical demands are ever-present and competition is everywhere.

Steve Horney

Fresh Look at Foam Rolling

Whether you are a therapist, trainer, or simply someone immersed in the health and fitness world, you are most likely very familiar with the use of the foam roller for myofascial release. The foam roller has numerous functions, but its aid in releasing the fascia and underlying muscle tissue is certainly its most popular. Despite this fact, I constantly witness patients or clients who seem uncomfortable on or frustrated with this modality.
Incorrect positioning on the roller seems to be what keeps most beginners from realizing the maximum benefits of the exercise. The following video is an attempt to help us rectify common issues people encounter. Using some of these basic tips with patients will hopefully change the mindset they have about the quality of this stretching method.
WATCH VIDEO

Wesley Thornton

Low-Level Laser Therapy May Be Helpful for Chronic Neck Pain

Due to the positive response generated from the last LLLT article, I thought I’d add to the current research on this modality.
New meta-analyses reported in the lastest online edition of Lancet report positive pain outcomes for LLLT for patients with acute and chronic neck pain.
The authors summarize, “Whatever the mechanism of action, clinical benefits of LLLT occur both when LLLT is used as monotherapy and in the context of a regular exercise and stretching programme,” the review authors conclude. “In clinical settings, combination with an exercise programme is probably preferable.”
See Medscape for further details of this article.
Again, I would like to see recommended dosage/wavelength parameters with regards to LLLT and specific injuries. Only after pooling the results of such double-blind placebo trials can we develop standardized parameters for the use of LLLT.

Benjamin Gold

Back Pain Treatment Review

While perusing the wellness section of NYtimes.com this morning, I came across an old article that reviewed options for treatment of non specific low back pain. This article went through the “gamut” of treatments from pharmacological treatment, spinal injections, and surgeries. The whole gamut?? What happened to physical therapy? Exercise? There was a very brief mentioning of physical therapy but seriously:
Indeed, many back pain specialists are now evaluating their patients daily exercise habits and emotional stresses. The new standards are a small step, but one reflective of the growing realization that pain, in all its forms, must be approached more holistically. But realization now dawning on physicians has not yet been felt by insurers. Health plans pay for surgery, drugs and spinal injections, but rarely for long-term physical therapy, psychotherapy — or joining a gym.
Noted Dr. Portenoy, “Training people to do the right thing doesn’t necessarily work in the real world if you’re only reimbursed for interventions.”
This article is proof in the pudding; people still are not as aware as they should be about the benefits of physical therapy. The medical world still seems to be turning to pharmacological or surgical solutions. Physical therapy is not only successful at helping to treat non specific low back pain, but also is much more conservative financially (the average cost of spinal fusion surgeries costing $59,000 according to the NY time article).
An article published in the British Medical journal in 2005 showed the average cost of spinal surgery versus physical therapy was almost half ($14,000 vs $8,100 respectively). This in a country with socialized medicine. And not only was physical therapy cost effective, but the study also showed that the reduction of disability after 2 years of treatment was about the same (surgery showed a little bit more improvement but the study states that future surgeries and complications had to be considered).
Physical therapists need to continue to become more active advocates for their profession. Like I have said before, get out there and educate your community. Meet with physicians, surgeons, local gyms, and anyone in your area related in the health field that can benefit from knowing what a physical therapist actually does.

Ryan Orser

Bikes in NYC Office Buildings

We are excited about NYC’s new law that mandates commercial landlords allow bicycles into office buildings (the only caveat is that the building must have a freight elevator).
As a business with a very active clientele, we have many patients (and employees) that want to ride their bikes to our clinic. It has been a bit of an embarrassment (and lost revenue) when the doormen of our building would not allow patients to bring their bikes up (and we have had to cancel appointments as patients would not dream of locking their race bikes up on a NYC street).
Now onto the more interesting battle – the hand-to-hand combat with a NYC landlord. Now that the City has put the law into effect, how long will it take to get landlords to comply with the new law? I just sent the first email to our landlord, politely asking if the building is ready to comply with the law. I will update as to how this progresses as I expect there to be strong resistance.

Adam Banks

A Healthy Perspective

After a long weekend away from the clinic, I was flying back home while watching a documentary on the National Geographic channel about the Iraq War and the lives of different soldiers that were there. After two hours of many times gruesome footage, I began to have a new found idea of what some of my friends and patients have talked reguarding their experiences.
Today, I read this blog in the wellness section of the NYtimes about “Lessons from the War Zone.” Through war there have been many medical advances. The mere profession of Physical Therapy came about with the need for people coming back from war with limiting injuries. Physical therapy was started as a profession of caring and understanding. The patients’ needs were to come before the ideas of what their therapists thought was best for them. With the never-ending paperwork that most therapists loathe, we have to remember what we do day-in-and-day-out. We are here to help those who need it. To quote Dr. Coppola, a two tour surviving pediatric surgeon says, “I don’t think it takes going to war to realize how important it is to appreciate our patients as people, not as lines on a to-do list.”
When you are having a bad or frustrating day, remember what you are there to do. To many patients you are their saving grace from sometimes relentless pain.

Ryan Orser

Early Articular Changes?

Gretchen Reynolds reviews work by Michal Szczodry et al. in her New York Times Well article. She unpacks the progressive damage that may be caused by even low force articular cartilage trauma. These ideas support the physical stress theory proposed by Michael Mueller et al., which suggests that tissue is damaged without discrimination by either low force trauma applied over a large duration of time or by high force trauma applied over a small duration. The subsequent reaction to these traumas is governed in part by the intrinsic properties native to each tissue. To learn more, follow this thread.
Jonathan Jezequel

Caught Between a Talar Rock and a Hip Place

Context is king. Our context is the patellofemoral articulation without regard to congenital, structural pathogenesis. Patellofemoral pain syndrome (PFPS) describes an umbrella diagnosis that covers an approximated twenty-five per cent of all knee injuries. PFPS presents clinically as diffuse anterior or retropatellar knee pain which is most typically exacerbated by functional activities that involve knee flexion while under weight bearing context, such as stair negotiation, prolonged sitting, squatting or kneeling.4,9 Despite a rather comprehensive incidence, the precise pathomechanics of PFPS remain unclear in their entirety. Notwithstanding, two biomechanical theories dominate the literature. These theories may be divided broadly into two models: the local impairment model and the remote impairment model. The former implicates a neuromuscular imbalance among the distal vasti and the latter neuromuscular deficits across the proximal hip musculature. Each perspective will be discussed with regard to several fundamental articles, which represent current thinking built on research over time.
The Local Impairment Model
The local impairment model, to be more specific, examines the relative influence of the vastus medialis obliquus (VMO) and the vastus lateralis (VL) on the patella. As the distal contractile tissue of the vasti gradually interdigitate with and transition to tendon, the patella is invested. In this way, the VMO and the VL can directly impose tensile forces on the patella and draw it posteromedially or posterolaterally, respectively. PFP has been postulated to result from an imbalance between these forces, with the VL exerting a more dominant pull than the VMO, which tends to aberrate the patella laterally relative to the femoral trochlea.2,9,11 This deviation creates compressive and shearing stresses that degrade the patellar articular cartilage over time.
Controlled studies that have sought to elucidate the role of the VMO in PFPS have typically asked morphological or neuromuscular questions. A recent study published by Jan et al. in The American Journal of Sports Medicine examined the insertion level, fiber angle and volume of the VMO in PFPS knees compared to healthy controls. While variation did exist, the study could not determine whether the observed differences were the result of atrophy in response to pain or pain in response to morphology.2 Wilson et al. report a decreased in vivo VMO tendon strain in PFPS compared to healthy controls and with reference to the VL. Strain defines change in length per initial length and is purported to reflect VMO weakness in this study.11 Among a cohort of male cadets of the Belgian Royal Military Academy, Van Tiggelen et al. found that delayed VMO to VL onset timing predicts PFP in previously healthy knees. The study was constructed prospectively and correlates delayed VMO neuromuscular activity with the development of PFP after six weeks of basic military training.9 Having collected electromyographic VMO, VL and tibialis anterior data only, one may only speculate whether or not additional predisposing variables subsisted prior to basic military training and, further, if these were primary and vasti timing ancillary to the development of PFPS.
These suspended questions aside, resistance training has been shown to enhance vasti neuromuscular control in general and independent of mode. Wong and Ng report enhanced EMG characteristics of the VMO relative to the VL after eight weeks of either strength or hypertrophy specific resistance training. These data lend direct relevance to clinical practice as both prospective and cross-sectional studies have linked global knee extension force deficits with PFPS.12 In this way, irrespective of the neuromuscular timing onset between the VMO and the VL, resistance training offers general and beneficial gains in knee extension force regardless of mode.
The Remote Impairment Model
The remote impairment model argues that PFPS is driven not directly from local deficits, but rather indirectly from proximal and distal pathomechanics. Internal femoral rotation, which may occur in isolation from or in accord with the tibia, tends to posture the knee in a valgus attitude. As the tibia interacts with the talocrural and talocalcaneal articulations, additional movement variables are introduced. For simplicity and scope, solely contributions from the femur will be considered at this time.
When excessive internal rotation occurs unchecked during weight bearing conditions the patella displaces laterally. Therefore, PFPS may result from the femur rotating underneath the patella rather than the patella tilting on a fixed femur.3,4,5,7 In following, the contractile tissues of the hip, specifically the iliopsoas, the gluteus medius and the gluteus maximus, work directly to accelerate and decelerate the femur through varied planes. Traditionally assigned pure sagittal plane movement, it is forgotten that the iliopsoas actually serves as a secondary external rotator and thus may influence transverse plane kinematics.8 Furthermore, an inflexible iliopsoas maintains the pelvis in an anterior pelvic tilt, an organization coupled with femoral internal rotation. Tyler et al. evaluated the importance of hip strengthening and flexibility in the treatment of PFPS and found a sixty-six per cent successful outcome after a six-week therapeutic exercise protocol. Having uniquely incorporated trial of the iliopsoas, Tyler et al. demonstrated a more significant correlation between hip flexion strength gain and a positive PFPS outcome as compared with hip abduction or adduction strength gain.8
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Using dynamic magnetic resonance imaging, Powers et al. reported that lateral patellar tilt and lateral patellar displacement during a weight-bearing squat was the result of internal rotation of the femur, as opposed to movement of the patella.3,4,5,7
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Powers and colleagues argue that the gluteus maximus and gluteus medius offer the greatest capacity for controlling internal femoral rotation. The gluteus maximus is a strong hip extensor and external rotator and claims the largest anatomical cross sectional area in the lower extremity.10 The gluteus medius functions primarily as a hip abductor, but secondarily generates an external rotation moment. Mascal, Landel and Powers established significant reductions in PFP, improved lower extremity kinematics and return to function after a fourteen-week therapeutic exercise regimen. The interventions focused on recruitment and endurance training of the hip, pelvis and trunk musculature and yielded significant improvements in gluteus medius and gluteus maximus force production as measured by hand-held dynamometry testing.3 Consequent to case study design and small study number, these results should naturally be generalized only with measured prudence.
Souza and Powers evidenced increased peak hip internal rotation motion in females with PFP compared to age-matched healthy controls when averaged across a drop jump, a step down and a running task. Hip extensor torque production was revealed to be deficient by sixteen per cent and hip abductor torque fifteen per cent. Moreover, gluteus maximus muscle activity showed ninety-one per cent greater muscle activity during running and sixty-four per cent greater activity during the step down maneuver. The authors conjecture that these data reflect cumulative attempts to recruit weak and indolent musculature.7
In a recent study published in the British Journal of Sports Medicine, Cowan et al. investigated the neuromuscular control of the anterior and posterior fibers of the gluteus medius in healthy controls and in the presence of PFP. Employing EMG, a step up task revealed both portions of the muscle to be delayed in the PFP group when referenced against the controls. Intriguingly, individuals with PFP were also found to have decreased trunk side flexion strength compared to asymptomatic individuals.1 These data are consistent with the work of Zazulak and colleagues who established that lateral angular trunk displacement deficits and low back pain predict knee injury in female and male athletes, respectively.13
Remarks
While the preceding review considered recent and fundamental primary literature under basic scrutiny, a complete examination of methodological and statistical power is beyond its scope. Despite a rather comprehensive incidence, the precise pathomechanics of PFPS remain unclear in their entirety. And although excellent thinking and competent studies support each model, it seems that no singular model holds absolute predictive strength in isolation. These and other data function most robustly in concert. From these studies we learn patterns and assemble trajectories to better anticipate and resolve pathology.
REFERENCES
Cowan SM, Crossley KM, Bennell KL. Altered hip and trunk muscle function in individuals with patellofemoral pain. Br J Sports Med. 2009;43:584-588.
Jan M, Lin D, Lin J, Lin CJ, Cheng C, Lin Y. Differences in sonographic characteristics of the vastus medialis obliquus between patients with patellofemoral pain syndrome and healthy adults. Am J Sports Med. 2009;37:1743-1749.
Mascal CL, Landel R, Powers CM. Management of patellofemoral pain targeting hip, pelvis, and trunk muscle function: 2 case reports. J Orthop Sports Phys Ther. 2003;33:647-660.
Powers CM. Rehabilitation of patellofemoral joint disorders: a critical review. J Orthop Sports Phys Ther. 1998;28:345-354.
Powers CM. The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective. J Orthop Sports Phys Ther. 2003;33:639-646.
Smith TO, Nichols R, Harle D, Donel ST. Do the vastus medialis obliquus and vastus medialis longus really exist? A systematic review. Clin Anat. 2009;22:183-199.
Souza RB, Powers CM. Differences in hip kinematics, muscle strength, and muscle activation between subjects with and without patellofemoral pain. J Orthop Sports Phys Ther. 2009;39:12-19.
Tyler TF, Nicholas SJ, Mullaney MJ, McHugh MP. The role of hip muscle function in the treatment of patellofemoral pain syndrome. Am J Sports Med. 2006;34:630-636.
Van Tiggelen D, Cowan S, Coorevits P, Duvigneaud N, Witvrouw E. Delayed vastus medialis obliquus to vastus lateralis onset timing contributes to the development of patellofemoral pain in previously healthy men. Am J Sports Med. 2009;37:1099-1105.
Voronov AV. Anatomical cross-sectional areas and volumes of the muscles of the lower extremities. Human Physiology. 2003;29:201-211.
Wilson NA, Press JM, Zhang L. In vivo strain of the medial vs. lateral quadriceps tendon in patellofemoral pain syndrome. J Appl Physiol. 2009;107:422-428.
Wong YM, Ng G. Resistance training alters the sensorimotor control of vasti muscles. J Electromyogr Kinesiol. 2009;doi:10.1016/j.jelekin.2009.02.006
Zazulak BT, Hewett TE, Reeves NP, Goldberg B, Cholewicki J. Deficits in neuromuscular control of the trunk predict knee injury risk. Am J Sports Med. 2007;35:1123-1130.

Jonathan Jezequel