Nike designed the new Nike Sole in conjunction with Foothill Ranch, CA-based Össur Americas, and elite triathlete and above-the-knee amputee Sarah Reinertsen.

Reinertsen, an athlete-spokesperson for the company as part of Team Össur from Orange County, CA, was born with proximal femoral focal deficiency, which led to amputation at age seven. At age 13 she broke the 100-m world record for female above-the-knee amputees. She is also the first female above-the knee amputee to compete in the Ironman Triathlon World Championship in Kona, HW, and holds world records in the marathon and half-marathon for women with above-the-knee amputations.

The  Nike  Sole  is  an  integrated layered sole. An outsole and midsole are topped by a layer of thermal plastic urethane called Aeroply, which is made of recycled Nike Air Bag units and serves as a moderator between the Nike Sole  and the  Össur Flex-Run’s carbon fiber  blade. Nine nylon plastic tabs serve as fingers that wrap snugly around the Flex-Run carbon fiber blade for secure lock down and easy on-off. A stretch rubber leash with a tactile grip tab for easy placement over medallion fasteners provides additional security.

Reinertsen tested the proto­type and worked closely with Nike’s designers so they could tweak the design based on her feedback.

Today she competes in marathons and triathlons using the Flex-Run and Nike Sole, which are available through prosthetists’ offices around the world.

The program will cover differential diagnosis of common foot and ankle problems, manual therapy techniques including mobilization, myofascial release, trigger point therapy, and general stabilization strategies such as footwear selection, simple inserts, and taping techniques.

This course will also provide an in-depth introduction to prolotherapy, offering information on efficacy, procedures, and indications.

On April 29, attendees can attend a fashion show featuring therapeutic footwear that emphasizes style and function. The event will support FootCentric’s mission to use revenue from continuing education programs to provide devices for people without resources to purchase the orthoses, shoes, braces, or other items critical to foot health.

For more information visit www.footcentriconline.com, where you can register starting February 28. If you have questions, call 919/433-7515.

Highlights include a new slip-resistant diamond tread for the Originals line and expanded options in the water-resistant, eco-friendly Adventure line.

Footwear choices also include gladiator sandals, athletic styles, boat shoes, and Mary Janes.

The Spring/Summer 2012 collection is available online at www.pediped.com and in select retail stores.

Already a seasoned distance runner when she suffered her injury in 2004, Deloria tried to return to the road using a heavy molded orthotic brace that limited her mobility. She eventually found Allard’s ToeOff Brace, a carbon fiber orthotic device designed to mimic natural movement of leg and foot muscles.

After four months of training in the brace, Deloria ran the Chicago marathon, completing it with her fastest time ever for that race. She kicked off her 20-race schedule in January, running in the “Rock and Roll” marathon in Phoenix, AZ.

The author, biomechanist Katy Bowman, MS, looks at mechanical contributors to common foot ailments, including whole-body mechanics and gait patterns, and presents an intrinsic strengthening program and a posterior leg muscle restoration program.

Visit www.footpainbook.com to download a free chapter and purchase the book, which is also available at Amazon.

The submission deadline for papers has been extended to March 15. Examples of topics of interest include business operations and administration, finance and billing, communications, professional and personal development, and more.

Submit your business presentation for consideration at https://aopa.wufoo.com/forms/2012-call-for-business-session/. For more information contact Tina Moran at tmoran@aopanet.org or 571/431-0808.

The AOPA National Assembly is scheduled for September 6-9 at the Hynes Convention Center in Boston, MA.

By Cary Groner

It’s unusual for chronic conditions and acute injuries to share similar causes, but clinicians and researchers suspect just such a relationship when it comes to anterior cruciate ligament (ACL) rupture and patellofemoral pain (PFP) syndrome. If the etiological correlation proves accurate, the result could be preventive strategies targeting both problems, and in fact studies already suggest that such an approach works.

The subject was raised at the annual conference of the National Athletic Trainers’ Association (NATA) in New Orleans last June, in a forum moderated by Darin Padua, PhD, ATC. Padua, an associate professor in the Department of Exercise and Sports Science and director of the Sports Medicine Research Laboratory at the University of North Carolina at Chapel Hill, told LER that multiple factors apparently put athletes at risk for these problems. One clear factor is gender: women suffer ACL injuries at rates four to six times those of men and PFP syndrome up to 10 times as often as men.^1-5

Although gender itself isn’t a modifiable risk factor, researchers have begun to clarify the biomechanical effects of gender differences and have shown that some may be amenable to change.

“There can be knee valgus collapse due to a multitude of different muscle imbalances,” Padua said. “You need to figure out the underlying cause and design an intervention to address it. In doing so, you’ll be more effective and efficient in being able to prevent these injuries, and in rehabilitating individuals who suffer them.”

All in the hips

In a 2010 literature review and analysis, Christopher Powers, PT, PhD, outlined the ways in which hip and trunk biomechanics may affect risk of knee injuries.⁶

Powers, director of the program in biokinesiology and codirector of the Musculoskeletal Biomechanics Research Lab at the University of Southern California, noted that impaired muscular control of the trunk, pelvis, and hip can affect tibiofemoral and patellofemoral joint kinematics and kinetics in multiple planes. In particular, the severe knee valgus often demonstrated by female athletes when landing after a jump results from excessive hip adduction and internal rotation.

Such problems often begin with diminished hip muscle strength, Powers wrote, and this has clear implications for PFP and ACL injuries because of their association with valgus knees and femoral rotation.⁷

“The risk factors are exactly the same for PFP and ACL injury: hip internal rotation, hip adduction, quadriceps overuse, and lack of hip strength,” Powers told LER. “I wouldn’t be surprised if at some point we figure out that patellofemoral pain is a predictor of who goes on to tear their ACL.”

Padua agrees about the sources of the problem.

“Neuromuscular control at the hip is a big factor, because the knee is pretty much a slave to what is going on at the hip,” he said. “An inability to control frontal and transverse plane hip motion can set the knee up for increased loads that predispose it to patellofemoral pain or ACL injury. Weakness in any of the gluteal muscles, tightness in the hip adductor or flexor muscles, any kind of muscle imbalances there could set an individual up for the lack of neuromuscular control that will predispose them to these injuries.”

Irene Davis, PT, PhD, director of the Spaulding National Running Center in the Department of Physical Medicine and Rehabilitation at Harvard Medical School, also emphasized the role of the hip.

“Analysis of films of someone tearing their ACL often reveals a mechanism of hip adduction and internal rotation,” she said. “These same mechanics are related to patellofemoral pain syndrome. The major contributors to the positioning of the knee in the frontal and transverse plane are not the sagittal plane muscles, but the hip adductors and external rotators. Therefore, interventions are going to be similar between PFP and ACL issues.”

PFP research

Existing research helps elucidate the manifold factors that appear to play into both PFP and ACL injuries. A 2009 paper on PFP—based, interestingly, on data from the Joint Undertaking to Monitor and Prevent ACL Injury (JUMP-ACL) project—noted that risk factors for PFP included decreased knee flexion angle and increased hip internal rotation during jump landing.⁸

A 2010 prospective study in Clinical Biomechanics reported that in 240 adolescent female athletes followed through the course of a season, those who developed PFP had increased knee abduction moment compared to teammates without PFP. And although 16.3% of subjects began the season with PFP—a surprisingly high number—adding in those who then developed PFP raised the total prevalence to 22%, further underscoring the need for screening and prevention.

A 2009 study in the American Journal of Sports Medicine reported that women with PFP (n=19) had significantly greater average hip internal rotation than controls (n=19), and concluded that patellofemoral pain resulted from diminished hip muscle performance rather than altered femoral structure.⁹ Another paper by the same authors noted that that hip muscle weakness included the extensors, abductors, and external rotators.¹⁰

A literature review from Erasmus University in Rotterdam, presented last September in Ghent, Belgium, at the Second International Research Retreat on Patellofemoral Pain Syndrome and e-published in October by the Journal of Orthopedic & Sports Physical Therapy, shed further light on causes and conditions. It included 37 studies of patients with existing PFP and reported that a larger Q-angle, less hip abduction strength, and lower knee extension strength were associated with increased PFP risk.¹¹

ACL research

Research into causes of ACL injuries reveals similar factors. For example, a 2005 paper in AJSM found that of 205 prescreened female athletes prospectively measured for neuromuscular control, the nine who later ruptured their ACLs had significantly greater knee abduction angle at landing than those who were not injured, and that abduction moment predicted ACL injury with 73% specificity and 78% sensitivity.¹²

In a 2008 paper in the Clinical Journal of Sports Medicine, researchers noted that after female athletes enter puberty and begin to grow quickly, gain weight, and increase their tibia and femur length, they may not match those changes with increases in strength and recruitment of the hip and trunk musculature. The result is a loss of core stability and trunk motion control during dynamic tasks—which, in turn, may underlie increased lower extremity valgus and elevate risk for ACL injuries.¹³ Similarly, investigators reported in 2011 that a 10-week neuromuscular training program affected not only knee abduction on landing, but also hip abduction angle.¹⁴

Numerous studies reveal other risk factors including knee joint laxity,¹⁵ a combination of knee hyperextension with excessive subtalar joint pronation,¹⁶ and acceleration and deceleration with excessive quadriceps contraction and reduced hamstrings co-contraction, as well as valgus loading.¹⁷

A 2009 study reported, moreover, that a correlation between quadriceps and hamstring strength and recruitment appears to affect ACL risk.¹⁸ Noting that hamstrings and quadriceps co-contraction provides dynamic joint stabilization and protect the knee during sports, the authors found that female athletes who injured their ACLs had a combination of decreased relative hamstring strength and high relative quadriceps strength, and suggested that targeted neuromuscular interventions to increase relative hamstring strength and recruitment could decrease risk.

Researchers have also proposed ways to identify athletes at high risk of ACL injury using clinic-based measurements and freeware computer analysis.¹⁹ In this approach, the authors validated a relatively simple way to identify female athletes with high knee abduction moment landing mechanics using an algorithm that incorporates measures of knee valgus motion, knee flexion range of motion, body mass, tibia length, and quadriceps-to-hamstrings ratio. They then used 3-D motion analysis to validate the approach.²⁰

Role players

It remains unclear which of these factors play the biggest role in the risk overlap between PFP and ACL injury, but researchers and clinicians are trying to find out.

“We’re doing what I call prospective biomechanical epidemiological studies,” said Timothy Hewett, PhD, professor and director of research at the Ohio State University Sports, Health, and Performance Institute, and director of the Sports Medicine Biodynamics Center at Cincinnati Children’s Hospital. “We bring the kids to the lab and test their movement patterns, strength, laxity, and other measures; get information about demographic variables, sports and injury history; then let them go out and play their sports.”

Hewett and his colleagues, including Greg Myer, PhD, research instructor of sports medicine at Cincinnati Children’s Hospital, have, in fact, determined that some of the factors that predispose subjects to PFP are similar to those they’ve found for ACL risk.²¹

“What we’ve previously reported for ACL—valgus torque of the knee, the lack of hip abductor torque—all fed this model of what predicted risk of future patellofemoral injury,” Hewett said.

And even though muscle weakness has often been cited as a source of risk, he drew a distinction between weakness and activation.

“In general, we don’t find hip muscle weakness a problem [for either PFP or ACL injury], but rather under-recruitment of the musculature during high-speed, sport-specific movements,” he explained.

The conclusion reflects on the aforementioned JUMP-ACL study of military recruits that correlated greater hip external rotator strength with PFP.⁸

“Those findings were directly counter to what would be expected, but it showed that it’s not hip strength that’s most crucial, but rather hip muscle recruitment,” Hewett said.

His colleague, Myer, emphasized the point.

“We think one reason [PFP and ACL injuries] are more common in women is that they don’t naturally jump and land with the proper hip recruitment needed for control,” he said. “If they don’t have active control from the muscles, they’re going to be more reliant on passive control from their ligaments—but because women often have looser ligaments as well, it’s a double whammy that magnifies the risk.”

Irene Davis has reached similar conclusions in her work in runners, who are typically more prone to PFP than ACL problems.

“Strengthening the muscles doesn’t necessarily change the mechanics,” she said. “That’s why we do gait retraining for people who have anterior knee pain while running.”

In her own research, Davis found that feedback was essential for changing motor patterns.

“You have to give feedback, then remove it systematically so you increase the person’s self-reliance on their own internal cues,” she explained. “It’s brain training, and you’ve got to get them to the point where it becomes their automatic pattern.”

Intervention strategies

Once shared risk factors are recognized, it becomes easier to design interventions to prevent injury.

“In all kinds of sports, you want that leg to be as well aligned as possible, because then the forces will be distributed more normally within the joints,” Davis said. “Interventions should address that abnormal alignment—hip adduction, femoral internal rotation, genu valgus, knee external rotation. This involves engaging the hip abductors and external rotators.”

Myer agreed that the primary focus of prevention should be correcting any underlying biomechanical flaws.

“We’ve been trying to correct these jumping and landing mechanics females tend to have—that tendency to land in a knock-kneed position, which torques the ACL and puts it at risk, and disrupts the patellofemoral joint and puts the knee cap in an abnormal position,” he said.

The training interventions Myers and colleagues have developed aim to improve those knee-flexion dynamics and control the out-of-plane positions, thereby reducing injury risk.

“Recruitment of the gluteus maximus, especially, is a big player in lower extremity alignment, so we try to modify that,” he said.

Several papers by Hewett, Myer, and their colleagues delineate the evolution of their approach. As early as 1996, Hewett published a paper describing a training regimen designed to improve jump-landing mechanics and lower extremity strength in 11 female high school volleyball players.²² All of the subjects demonstrated a marked imbalance between hamstring and quadriceps muscle strength before training. The approach, which the authors termed “plyometric,” included a variety of jumps—wall jumps, tuck jumps, squat jumps (to name just a few), as well as bounding exercises and single-leg hops—and was designed to decrease landing forces by teaching neuromuscular control. The training program corrected the hamstring/quadriceps (H/Q) imbalance, and both adduction and abduction knee moments decreased significantly at landing. The study demonstrated that H/Q balance is critical to knee motion control; 10 of the 11 subjects successfully reduced their peak landing forces.

In 2005, Myer, Hewett, and colleagues reported in the Journal of Strength and Conditioning Research that 41 female teenage basketball, soccer, and volleyball players who underwent six weeks of neuromuscular training increased their knee flexion-extension range of motion during landing and significantly decreased both valgus and varus torques.²³ The training included four main components: plyometric and movement, core strengthening and balance, resistance training, and speed training.

Other studies by these researchers have shown that plyometric training and a combination of dynamic stabilization and balance training each reduce lower extremity valgus measures during drop landings;²⁴ that each of these approaches alone also increased lower extremity neuromuscular power and control;²⁵ and that female high school athletes deemed at high risk for ACL injury based on measures of knee abduction moment significantly reduced abduction following neuromuscular training (though not to the level of those in the low-risk group, who had little reduction in knee abduction torque following training).²⁶ They also showed that 10 weeks of trunk-focused neuromuscular training in 21 female high school volleyball players significantly increased standing hip abduction strength, which could improve the athletes’ control of lower limb alignment and decrease motion and loads resulting from increased trunk displacement during sports.²⁷

In the past few years, research has begun to show that such interventions affect injury rates. In a study of 1263 high school athletes, untrained female athletes (n=463) had an incidence of knee injury 3.6 times higher than female athletes given neuro­muscular training (n=366). The latter group, moreover, had rates roughly equivalent to untrained male athletes (n=434), suggesting that the training erased the usual difference in injury risk between genders.²⁸

In a study of a Santa Monica intervention program called PEP (Prevent injury, Enhance Performance), researchers reported that neuromuscular and proprioceptive training lowered the ACL injury rate in adolescent female soccer players by 88% in the first year.²⁹ A later study by some of the same investigators found that in 1435 female NCAA soccer players, those who received the training had an ACL injury risk 1.7 times lower than controls.³⁰

Chicago researchers developed a neuromuscular warm-up based on the techniques described by Hewett, Myer, and their associates, as well as the PEP program, and implemented it in the city’s urban public schools. Ninety coaches and 1492 athletes completed the randomized trial, in which student athletes received either the 20-minute neuromuscular warm-up or a standard warm-up before practices and games.³¹

The results were striking: Athletes who received the intervention had roughly a third to half the injury rate of controls for gradual-onset lower extremity injuries (including PFP), knee sprains, and ACL sprains. Incidence of ACL sprains dropped from 0.26 per 1000 athletic exposures in the control group to just 0.07 in the intervention group.

“We targeted this population because most of the research had been done in more homogeneous suburban populations with better resources, and we wanted to know if coaches functioning in this environment could learn the program and implement it con­sistently,” said Cynthia LaBella, MD, the paper’s lead author.

LaBella, an associate professor of pediatrics at Northwestern University’s Feinberg School of Medicine and medical director of the Institute for Sports Medicine at Children’s Memorial Hospital in Chicago, believes there is significant overlap between ACL and PFP risk factors, and that the training program addresses both. In a previous paper, she reported that similar training reduced knee pain in adolescent female athletes.³²

Lindsay DiStefano, PhD, ATC, an assistant professor of kinesiology at the University of Connecticut and one of the panelists at the NATA forum, believes that, fundamentally, all such approaches go back to teaching young people to move well.

“We have to teach kids how to control their bodies—how to land well, cut well, with good technique,” she said.

She noted that in the JUMP-ACL study, for which she was a research assistant, individuals who developed PFP didn’t have significant strength or postural differences from those who did not develop the condition.

“The risk factors for both injuries are movement-based,” she said. “People who don’t absorb forces as well, who have a lot of frontal and transverse plane motion, are most likely to get injured.”

Compliance

One consideration when assessing such programs is how well athletes and their coaches will persist down the stretch.

“There’s good evidence that prevention programs work; the problem is that often you go back a year later and people have stopped doing them,” DiStefano said. “We have to figure out ways to make exercises more efficient and effective so coaches and athletes adopt these programs as part of their normal practices.”

In Chicago, according to LaBella, the prevention program was so popular that it’s spreading rapidly as students move and coaches change jobs, taking it with them.

“These folks are hungry for professional development and education to better their coaching skills,” she said. “They’re very appreciative, and they feel like it’s an important program that they want to keep using.”

Cary Groner is a freelance writer based in the San Francisco Bay Area.

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Survey results suggest that at least one-third of individuals at risk for foot pain or diabetic foot ulcers are wearing shoes that are at least one size too big or too small, which can further increase those risks. Proper shoe fit and foot health start with patient education.

By Stephanie Swensen, BSc, and Ran Schwarzkopf, MD, MSc      

The high prevalence of foot pain and poor foot health has increasing implications for the aging population. Recent data from the Framingham Foot Study demonstrated that approximately 25% of the population (19% of men, 29% of women) report generalized foot pain on most days.¹ Poor foot health appears to be most marked among elderly and diabetic patients, and a study by Menz et al found an 87% incidence of foot pain in older adults.²

Similarly, diabetic foot ulcers are among the most common and severe complications of diabetes, with an estimated lifetime risk of 15%.³ Among the numerous contributing factors, improperly fitting shoes play a significant role in the development and exacerbation of foot pain and injury. Thus, proper shoe size is a particularly important element of foot health and overall quality of life within these populations.

Ill-fitting shoes are a common mechanism for the pathogenesis of foot ulcerations and pain. Shoes that are too small produce constant localized pressure, most commonly on the medial and lateral surfaces of the foot. Too-large shoes can cause friction ulcers behind the heel as a result of the foot sliding within the shoe.^4,5 Additionally, foot-shoe size mismatches can disrupt the biomechan­ics of the foot and ankle, predisposing the wearer to pain and falls.^6,7

The high prevalence of individuals with unequal foot sizes further complicates proper shoe sizing and increases the risk of foot injury; prevention of this problem requires the purchase of different shoe sizes for each foot.⁸ One study by Kusumoto and Ashizawa showed that only 33% of their cohort had equal left and right shoe sizes.⁸ Therefore, in addition to footwear’s function as an environ­mental barrier, shoe selection should include consideration of the pressure, shear, and shock experienced by the foot. Matching the dimensions of each foot to its respective shoe will help minimize the negative effects of those forces.

Our extensive review of the literature reveals that improperly fitting shoes are often associated with the complications of foot pain and ulcerations, particularly within the elderly and diabetic patient populations. Additionally, our previous research demonstrates the prevalence of foot-shoe size mismatch within the population and the high proportion of adults who are unaware of their own shoe size.

Diabetes and foot-shoe size mismatches

One of the most pronounced pathophysiologic consequences of diabetes is peripheral neuropathy, which has been reported to occur to some degree in more than 50% of patients with diabetes older than 60 years.⁹ Severe peripheral neuropathy results in loss of protective sensation, increasing the risk of physical trauma.¹⁰ In an examination of factors contributing to diabetic foot ulcers, MacFarlane et al reported that skin rubbing from footwear was the most common precipitant of ulceration. In that study an estimated 20.6% of foot ulcers in patients with diabetes were due to the shearing force applied to the skin from ill-fitting shoes.¹¹

Patients with diabetes suffer from a multitude of lower extremity complications and are 10 to 30 times more likely to undergo lower leg amputation than patients without diabetes; 85% of nontraumatic amputations in patients with diabetes occur subsequent to foot ulceration.¹⁰ Properly fitting shoes are of utmost importance in the care of diabetic patients, as the consequences of shoe-related foot microtrauma are costly and because individuals with peripheral neuropathy may not be capable of noticing the discomfort of poorly fitting shoes. Practitioners should not only assess patients’ need for therapeutic shoes but also the correct size and fit of their patients’ shoes.

A recent study by Harrison et al⁷ examined correct shoe sizing in patients with diabetes. In this study two-thirds of the patients were wearing shoes that were incorrectly sized for their feet. Most notably, 45% of patients wore shoes of the incorrect width.  Additionally, 45% of patients reported previous foot problems, including ulcers, calluses, bunions, corns, or edema.

A previous study by Reddy et al⁵ showed that 37% of patients with diabetes were wearing too-tight shoes compared with 24% of general medical patients. Reddy further demonstrated that the wearing of tight shoes was associated with callosities in those with diabetic neuropathy. Interestingly, no increased incidence of callus was noted in those wearing tight shoes in the general medical group or in those with diabetes who did not have neuropathy.

Another study by Nixon et al¹² confirmed the discrepancies in foot and shoe size among patients with diabetes. They assessed 440 Veterans Affairs patients, 58.4% of whom had diabetes and 6.8% of whom had an active diabetic foot ulcer. Only 25.5% of these 440 individuals wore appropriately sized shoes, and those with diabetic foot ulcerations were 5.1 times more likely to wear poorly fitting shoes than those without a wound.

The findings from these studies demonstrate the necessity of adequate shoe sizing, particularly in the diabetic population most at risk for foot ulcerations and related complications. Repetitive foot measurements should also be encouraged, given the resultant progressive change in foot shape and size that occurs with the disease and with age. Concomitant daily foot checks will also lessen the risk of ulceration from footwear.

Risks in older nondiabetic patients

An examination of the literature reveals evidence that foot pain becomes increasingly problematic later in life in all adults, not just individuals with diabetes.  Burns et al showed that older nondiabetic patients have similar rates of foot disease as their peers with diabetes.¹³ In addition to diabetes, conditions including peripheral vascular disease, peripheral neuropathy, neuromuscular diseases, and inflammatory arthropathy, predispose older individuals to foot problems, as do poorly fitting shoes.

Foot pain is particularly detrimental in the older population as it can severely impact individuals’ functionality and independence. Characteristic age-dependent alterations in feet often complicate proper fitting of shoes in older populations. For example, studies have noted that with age, the width and height of the forefoot increase more than hindfoot width and height.^14,15

Improper and ill-fitting footwear also contributes significantly to functional limitation in older adults. Burns et al¹³ recently investigated the proportion of elderly people on a general rehabilitation ward wearing incorrectly sized shoes. Nearly three quarters (72%) of the 65 patients in the studied population were wearing ill-fitting shoes. However, only 6% had shoes that were too small while 65% had shoes that were too large. None of the six patients with diabetes were wearing correctly sized shoes. Incorrect shoe length was significantly associated with the presence of ulceration and pain.

Paiva de Castro et al similarly demonstrated improper shoe fit in a series of 399 older adults.¹⁴ Too-large shoes were identified in 48.5% of women and 69.2% of men; the feet of those wearing the wrong size had greater width, perimeter, and height than the feet of those wearing correctly sized shoes. Incorrect shoe size was significantly associated with ankle pain in women but not in men or in patients with diabetes.

In addition to foot pain, poorly fitting shoes have also been associated with an increased risk of falls in older individuals. Many studies have focused on the type of shoes implicated in accidental falls; however, very few have examined foot-shoe size mismatches. Barbieri et al conducted interviews with elderly patients who had fallen while hospitalized and found that poorly fitting shoes played a role in 51% of the incidents.¹⁶

Three main shoe features have been shown to affect postural stability: the cushioning properties of the midsole, the slip resistance of the outer sole, and the height of the heel. Combined with ill-fitting shoes, these factors might contribute to an increased rate of falls,¹⁷  and research has shown that foot problems are more prevalent in older patients with a history of multiple falls than in those who have not fallen or have fallen only once.²

Menz et al followed 176 residents of a retirement village for 12 months; 41% of the individuals reported falling during this period.¹⁸ Fallers had an increased incidence of decreased ankle flexibility, severe hallux valgus deformity, decreased toe plantar flexor strength, decreased plantar tactile sensitivity, and an increased rate of disabling foot pain. The authors concluded that interventions to address these factors, including proper shoe fitting and medical surveillance, can be part of a falls prevention strategy.¹⁸

Mickle et al made similar recommendations in their study, which assessed 312 individuals for hallux valgus, lesser toe deformity, and toe flexor strength.¹⁹ They demonstrated a 35% fall rate during the 12-month study, and concluded that reduced toe flexor strength and the presence of toe deformity increased the risk of falling among their study group of older adults. The authors noted that interventions designed to address these issues combined with appropriate and well-fitting footwear might lower the incidence of falls in this population.¹⁹

As with diabetic patients, practitioners should take special care to properly fit shoes to the older patients’ changing foot sizes to prevent the development of pain, falls, and limitations in mobility and function.

Our experience

Given the aforementioned importance of properly fitted shoes, particularly in at-risk populations, we sought to determine the proportion of adults who are unaware of their own shoe size in three very different New York City populations: a foot specialist private office practice, an academic diabetic foot and ankle clinic, and a charity care center serving the homeless. We also examined patient demographic data and history of diabetes and ulcers to determine potential associations with shoe sizes.²⁰ Of the 235 participants, 34.9% wore ill-fitting shoes at least one size too large or too small and 11.9% wore shoes with a discrepancy of at least 1.5 sizes. Additionally, more than 90% of patients did not know their shoe width.

In contrast to the findings of Paiva de Castro et al,¹⁴ which indicated that male gender was associated with foot and shoe size mismatch, our study results found a higher association between female gender and shoe size mismatch. We did not examine the association between foot and shoe size mismatch and foot pain as did Paiva de Castro et al did in their study, which showed a higher association among females between foot pain and shoe size mismatch.¹⁴

Like the findings of Kushumoto and Ashizawa,⁸ our study showed a statistically significant difference between the right and left foot size among patients with a foot-shoe size mismatch; in addition, 60% of our patients with a shoe-to-foot mismatch had a difference between their right and left shoe sizes. This finding further highlights the need to size the larger foot to prevent the detrimental effects of pressure that would result from sizing only the smaller foot.

Interestingly, a significant connection was found between prevalence of foot-shoe size mismatch and clinic location. The patients from the private practice office had a significantly lower rate of poorly fitting shoes than patients from both the academic diabetic foot and ankle clinic and the charity care center. However, the academic clinic and the private office had a similar payer mix, making difference in socioeconomic status an unlikely cause of the differing findings. We speculate that the lower rate of poorly fitting shoes among the patients from the private practice may be due to the lower rate of diabetes among this group. We recommend a high level of vigilance when monitoring foot-shoe size mismatch among diabetic patients.

Conclusion

Our findings confirm previously recognized observations that a large proportion of patients wear improperly sized shoes. Although differences were observed in various clinic settings, nearly all patients were unaware of their accurate shoe size, regardless of education level. Therefore, counseling on proper shoe fitting is warranted to prevent the numerous complications of foot-shoe size mismatch.

We recommend that practitioners integrate a routine manual foot measurement during the patient’s annual or biannual office visit. Foot measurement should include both foot length and width. Furthermore, as the results of our study have shown, a high rate of left-to-right side foot-shoe size mismatch exists, and we highly recom­mend measurement of both feet during the exam. Not only should the practitioner assess the patient’s foot size during the exam, he or she should also evaluate the proper fit of the patient’s shoes and the possible need for customized shoes. Such protocols will help eliminate foot problems that occur due to improper shoe fit.

Ran Schwarzkopf, MD, MSc, is an associate professor of orthopedic surgery at Brigham and Women’s Hospital and Harvard Medical School in Boston, MA. Stephanie Swensen, BSc, is attending New York University Medical School and is a research assistant at NYU Hospital for Joint Diseases in New York City.

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This study found that closed basket-weave ankle taping significantly affects ankle range of motion and time to peak vertical ground reaction force, which can have implications higher up the kinetic chain that appear to vary from one indivi­dual to another.

By Matthew L. Santos-Vitorino, MS, ATC, LAT, Sue Shapiro, EdD, ATC, LAT, Kathy Ludwig, PhD, and Claire Egret, PhD

In the current era of medicine, everything is questioned. Curriculum and practice worldwide have adopted an evidence-based approach, with the goal of validating everything being done for patient health care. The same is true with allied health and sports medicine professions. Practices that have been used for decades are now being reevaluated and sometimes discarded if they are not proven beneficial. Yet one of the most performed tasks in sports medicine, ankle taping, remains a mainstay of practice despite little published evidence of its benefit on the lower extremity.

Ankle sprains are one of the most common injuries in sports. To combat this problem standard practice by most sports medicine clinicians is to either tape or brace the joint.¹ These restrictive modalities decrease range of motion (ROM) to lower the risk of further injury.¹ The ankle taping system also affects overall ankle proprioception,² as general consensus is that ankle injuries recur due to the loss of proprioception caused by initial injury.³

There is insufficient data showing the effects of closed basket-weave ankle taping on lower extremity kinetics and kinematics. Many studies^1,2,4,5 have focused on single aspects of kinetics or kinematics in the lower extremity or on a single joint, but few studies utilizing motion analysis have demonstrated a broader kinetic or kinematic basis for ankle taping.

Literature

Many past studies have examined aspects of ankle taping and its relationship to ROM, reaction time, and postural stability. University of Wisconsin researchers⁶ examined muscle latencies during unexpected inversion stress. In this study, participants were placed on an apparatus designed so that one side could drop at any time, resulting in unanticipated ankle inversion. Electromyography demonstrated that muscle latencies during inversion were not affected by bracing with a semirigid hinged ankle brace.  This is important because bracing is utilized less often than taping^1,2,4 and has been shown to restrict ROM to a lesser degree,^4,7,8 though more recent research suggests that may be true only for dorsiflexion.⁹ A 2000 study⁹ found that bracing decreased plantar flexion, inversion, and eversion ROM at the ankle to the same degree as taping, and the limit in ROM for dorsiflexion was significantly greater with tape.

One study by DiStefano et al⁵ examined ground reaction force (GRF) after forced dorsiflexion, then again after maximal plantar flexion, while the participants were braced. The authors concluded that ankle braces significantly decreased sagittal plane ROM at the ankle and significantly altered knee flexion during landing.⁵ Despite the significant changes at the ankle and knee, no significant change was found in the vertical GRF sustained during landing.⁵ This study is more relevant to sport because it looked at forces generated during plantar flexion, a motion predominantly used in athletics for power and locomotion.

Muscle length and power

The idea that force is related to length of a muscle has been discussed for many years.¹⁰ More than 100 years ago, physiologist Magnus Blix showed that muscle length was key in determining maximum isometric power.  In a series of three papers published from 1891 to 1894, Blix determined that muscle force production, whether at a maximal or submaximal level, was dependent on length.¹⁰

A recent study by Ruiter et al¹¹ concluded that the length dependency of force production output during concentric contractions differed from that during a maximal isometric contraction. As a muscle lengthens, but before it over-lengthens, there is a point at which maximal cross-bridge attachments can be attained. Ideally, this is where the greatest amount of power can be generated. In addition to the concentric forces muscles produce, research^10,12-16 shows that eccentric muscle function is crucial for producing shock-absorbing and energy efficient movements. These eccentric muscle contractions add stability and protection during human movement.¹² There is an inverse relationship between the force on a muscle and the speed with which that muscle can be shortened.¹³

Limitations of bracing and taping

More recent research has examined the possibility that restricting motion at the ankle can negatively affect motion at the knee, potentially increasing the risk of knee injury.^17-20 This line of investigation has also been discussed in the nonresearch community.²¹ Several studies suggest the decrease in normal ankle kinematics can lead to overcompensation at the knee, leading to the increased risk of injury.^18-21 Despite these numerous findings that suggest a negative global effect on proximal joints when the ankle is taped, more recent studies fail to show an increased risk with braced ankles.²² A 2011 study of California high school athletes found that lace-up braces not only decreased the occurrence of acute ankle injury but also produced no increased risk of knee injury.²² Though the study applied a commonly used ankle brace, the lace-up brace is less effective at restricting ROM, especially in dorsiflexion, compared with tape.^3,8 This is important because tape is still the more commonly used method of reducing ROM at the ankle.

We conducted a study to investigate whether ankle taping allows the ankle to sustain a greater amount of GRF than an untaped condition, and if there are differences between genders and in ROM. We also assessed muscular activity and impulse differences between taped and untaped conditions. Another aim of this study was to see if there were changes in kinematics and VGRF between men and women while in the taped condition.

Methods and materials

Our study involved 19 volunteer participants (nine women); all were college athletes aged 18 to 23 years. Participants were free of ankle injury within the previous six months and were able to perform the following actions without any sign of struggle or discomfort: five-minute jog at three mph; jumping from a predetermined landmark; and landing after jumping.

Investigators asked participants to perform active dorsiflexion and plantar flexion and measured and recorded ROM with a 12-in Jamar goniometer. Measurements were taken three times for both dorsiflexion and plantar flexion, and an average was used when processing data. Investigators collected dorsiflexion and plantar flexion data while participants were both taped and not taped.

Next, the participants were equipped with a series of reflective markers placed on top of their clothes and skin. A total of 16 markers were placed on the participants’ bodies from waist to feet. Researchers placed markers placement bilaterally and on the anterior superior iliac spine; posterior superior iliac spine; midthigh; joint line of the knee; midshaft of the fibula; lateral malleolus; calcaneus; and the metatarsal phalange joint of the fourth toe. The markers were used in conjunction with a seven-camera motion capture system for motion analysis.

Participants then stood at a predetermined landmark and jumped onto the force plate with one foot in front of them, landing on the dominant leg (reported by participants before testing). Once contact with the force plate was made, each participant performed one maximal vertical leap, again landing on their dominate leg. This procedure was practiced up to 10 times or until the participant was comfortable with the action.

Participants repeated trials three times with tape and three times without tape; a standard coin flip determined the order of taped and nontaped trials. The taping technique used was the Gibney closed basket weave, the standard ankle taping used in athletic training.²³

Application of the closed basket-weave ankle taping for this study was performed as follows: the foot was placed on a table in front of the clinician, who applied adherent spray to the distal lower leg, ankle, and foot. Next, the clinician applied prewrap from the midcalf to the base of the fifth metatarsal. Two anchor strips were applied at the midcalf and two at the base of the foot. Following the anchor strips, a stirrup strip was placed from the medial aspect to the lateral aspect. Next, a horseshoe strip was applied over the stirrup strip. This process of stirrup followed by a horseshoe was repeated three times. After the stirrups and horseshoes, two sets of heel locks were applied, alternating the beginning sides. Then, a figure eight was applied, beginning at the medial aspect of the lower leg and finishing on the anterior of the lower leg. Closing strips were applied from the foot end to the calf until complete.²³

Instrumentation

Investigators used a force plate installed in the floor of the biomechanics lab to measure GRF. This force plate is operated simultaneously with a seven-camera Vicon nexus motion capture analysis system. The Vicon system data was processed using Vicon nexus software.

Results

Kinematics. We found no significant interaction between gender and the taped condition on the combined dependent variable of dorsiflexion and plantar flexion (p > .05). There was no significant main effect for gender (p > .05). There was a significant main effect for the taped condition (p < .001). Follow-up univariate tests found significant differences within the taped and untaped groups for both dependent variables. Dorsiflexion and plantar flexion in the taped condition were significantly lower than in the untaped condition (dorsiflexion, p < .001; plantar flexion, p < .001). Both of these dependent variables had effect sizes greater than .800 (Table 1).

We found no significant interaction between tape and gender with regard to knee and hip functional ROM in the sagittal plane during landing, (p > .05). There was no significant main effect for tape (p < .05). However, there was a significant main effect for gender (p > .05), and follow-up analysis found that knee functional ROM was significantly higher in men than in women (p < .001). There was no significant difference in hip ROM between genders (p > .05) (Table 2).

Kinetics. Results of the multivariate analysis of variance (MANOVA) for the vertical GRF during jumping and landing show no significant interaction between gender and tape (p > .05) and no significant main effect for gender (p >.05) or for tape (p > .05).

Time to peak VGRF during landing. When studying the variable of time to peak VGRF, there was no significant interaction between tape and gender (p >.05) and no significant main effect for gender (p >.05). There was a significant main effect found for taping (p < .05). Time to peak VGRF was significantly shorter in the taped condition (Table 3).

These results show that the closed basket-weave ankle taping significantly decreases plantar flexion and dorsiflexion at the talocrual joint. The closed basket-weave ankle taping significantly increases joint ROM at the knee in men. Lastly, the application of tape at the ankle significantly decreases the time to peak VGRF during landing. The results also show that application of ankle taping did not significantly affect the magnitude of VGRF sustained by the body.

Discussion

This study of closed basket-weave ankle taping investigated several kinematic and kinetic effects on the lower extremity. Similar to the findings of Paris et al,⁸ our study found the application of ankle tape significantly decreased ROM for both plantar flexion and dorsi­flexion. As stated in previous literature, a restricted ROM affects the biomechanics of the taped joint as well as those of surrounding joints.^{13,14,18,24-26}

We also found that the time from initial contact to peak VGRF was significantly decreased with tape. This finding agrees with that of Saeki et al,²⁷ who in 1995 found that ankle tape was associated with decreased time from landing to peak floor reaction force in a side-step movement. They suggested that this significant change could affect VGRF absorption.

When analyzing the landing motion kinetically and kinematically, we see that the ability to control a landing and stay stable throughout the landing is dependent on muscles’ ability to contract eccentrically. As noted in previous research^10,11,13 eccentric contraction of the lower extremity musculature during landing absorbs the forces applied to the body. The length-power relationship dictates that longer muscle fibers elicit greater force, so if a decreased degree of ROM allows for less than normal lengthening of a muscle fiber, then decreased ROM will also lead to decreased force production from that muscle. The statistical significance of the decrease in time to peak VGRF shows that the time the body had to eccentrically contract was limited by the taping application. And if the time available for eccentric contraction was decreased, then the body’s ability to absorb the sustained forces was most likely affected.

One of three hypotheses can be made. First, if a muscle’s role as a stabilizer is limited by tape, that role must be filled through the compensatory action of another muscle. Second, the amount of force generated by the restricted muscle has to be increased over a smaller muscle volume. Finally, a larger amount of the VGRF sustained by the body is transferred to structures not typically involved in force attenuation.

In our male participants taped trials resulted in a 3° increase in knee ROM compared with untaped trials. In women volunteers, however, knee ROM decreased by 5° with tape. Even though this difference is not statistically significant, it may be important in clinical practice. These data show that women compensate for loss of ankle ROM and eccentric contraction capabilities by decreasing knee flexion, while men compensate by increasing knee flexion.

A study by Joseph et al²⁸ similarly concluded that the jumping and landing movements of men and women were significantly different. That study also suggested men and women utilize a completely different kinematic strategy while landing, and this difference tends to show women collapsing while landing and allows for a greater valgus ROM.²⁸

We can see trends in data on jumping and landing sequences, muscular recruitment, and women throughout several different studies. Yu and Garrett²⁹ found that women with decreased knee flexion while landing sustained a great amount of anterior cruciate ligament (ACL) loading, which could subsequently increase the risk of an ACL tear. Their study showed a direct correlation between decreased knee flexion in women and increased risk of injury to the ACL, while the current study showed how a taping application can decrease knee flexion 5° during landing.

Several studies^29-31 concluded that increases in knee valgus ROM leaves women at a greater risk of ACL injury. Combined with the findings of Pollard et al,³² this series of facts becomes more interesting. Pollard found that during a landing sequence, women who have decreased knee flexion also exhibited increased valgus angles.³² When coupling all the data from the female-based kinematic studies we see a trend that shows decreased knee flexion promotes increased valgus angles, leading to increased loads on the ACL.^29-32 Taken together with findings from the current study, which suggests ankle taping decreases knee flexion in women, this body of research shows potential a link between the use of ankle taping and increased joint loads on the ACL.

Further evaluation of individuals in our study produced astonishing results. One participant, for example, had at least 15% increases in VGRF at the ankle and in knee ROM and hip ROM with the application of tape. This same participant, also when taped, had a 23% loss in VGRF at the ankle during the take off following a landing. Another participant had decreases in all force production categories, increases in all VGRF categories, increases in functional ROM, and losses in time to peak VGRF. At least five participants saw individual trials vary at least 15% for all the VGRF categories as well as 10% changes, whether increases or decreases, in the joint moment categories.

On larger scale, every participant had a change of at least 15% (in some cases more than 25%) in at least two categories. These individual kinetic and kinematic changes in response to taping, which may have clinical importance, are masked when trial results are averaged. On the other hand, another negative effect of looking only at means is the inclusion of outliers that may not be clinically relevant.

Findings from this study show that closed basket-weave ankle taping significantly decreases active plantar flexion and dorsiflexion in the talocrural joint and decreases the amount of time from initial contact to peak VGRF. This suggests that a decrease in active ROM significantly affects the body’s natural eccentric muscle contraction, which is needed during the landing motion. Although no significant effect of taping was seen for VGRF, significant differences seen in ROM demonstrate that the application of tape results in biomechanical adaptations.

Clinical implications

Despite having fewer statistically significant results than expected, this study does have potential clinical implications. The variability in responses to taping seen in individual participants supports the idea that athletes are truly different; therefore clinicians should tailor its application to each athlete based on a clinical evaluation.

A review of the literature^1,4,33 found that 85% of all sprains in the body are ankle sprains and showed that the ankle can sprain in multiple ways; it makes sense that responses to taping would be similarly varied. With a better understanding of factors contributing to this variability, clinicians can improve their current approach to ankle taping at several junctures: prior to taping, by using an in-depth evaluation to predict an athlete’s individual response to tape; during taping, by positioning the foot to maximize support while minimizing compensatory effects; and in some cases, by deciding not to tape at all and completely preventing any potentially harmful effects. All of these paths to improved outcomes can be accomplished with thorough evaluation of each patient and the application of impeccable clinical skills.

The apparent effect of taping on the force-absorbing mechanisms in the lower extremity has potential consequences for athlete performance if force is being transferred to proximal joints or if the same muscles are working harder to compensate for ROM restrictions. The continued need to sustain these forces, especially for an untrained body, could lead to the increased risk of further ankle sprain, muscle strain, stress fracture, and other overuse and compensation injuries.

Conclusion

This study’s results indicate that closed basket-weave ankle taping significantly affects ROM and time to peak VGRF. These results, along with knowledge of the physical laws that act on the body, suggest that ankle taping has more biomechanical effects than assumed. Although this study did not find significant increases in VGRF or significant changes in the entire movement patterns of the lower extremity, results from individual participants show the restriction of ankle ROM can vary significantly among individuals and affect them differently.

The findings of this study add to existing knowledge about the effects of the ankle taping, but further research and new testing instruments are needed to find additional clinical evidence for recommending the prophylactic use of ankle tape. The need to understand ankle taping and its effects on biomechanics and performance is significant because of its widespread application in athletics. The possible trends seen by linking studies are alarming, and future research needs to more fully investigate issues at the kinetic and kinematic levels. In the age of evidence-based medicine, even such commonplace practices should no longer be used without in-depth investigation.

Matthew Santos-Vitorino, MS, ATC, LAT, is the head athletic trainer at Westminster Christian School in Miami, FL. Sue Shapiro, EdD, ATC, LAT, is associate professor and director of athletic training; Kathy Ludwig, PhD, is associate professor of biomechanics; and Claire Egret, PhD, is associate professor of biomechanics at Barry University in Miami, FL.

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