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The following articles report on research completed, in whole or in part, under a grant from ACPM. Thanks to all those whose voluntary contributions to ACPM’s Research Fund make such grants possible.
Comparing Negative Casting Techniques: Foam versus Plaster of Paris
Richard Berenter, DPM, FACFAOM
This study was undertaken to determine whether there was any difference in the clinical outcomes related to the type of negative casting technique utilized in the manufacture of functional foot orthoses. Those practitioners who favor foam casting blocks argue that the technique is cleaner, faster, more cost effective and just as reliable a method to produce functional foot orthoses versus the plaster of Paris technique. On the other hand, a number of practitioners have argued that the foam block technique is inferior because the foam is incapable of capturing the shape of the foot with the subtalar joint in neutral position and the midtarsal joint maximally pronated thereby leading to an inferior foot orthosis, which will be less effective at reducing patient symptoms.
Materials and Methods:
A total of 38 patients were enrolled in the study. All of the patients presented with lower extremity symptoms associated with abnormal lower extremity function as determined by gait evaluation. At the time of the initial visit, each patient signed a consent form and completed the top portion of the data sheet which included both personal information and the amount of pain in each extremity (patients were asked to circle the amount of pain on a scale from 0-10 with 0 being no pain and 10 being the worse pain ever felt).
Upon completion of all paper work, both feet of each patient were casted via the semi-weight bearing foam block technique and by the non-weight bearing supine plaster of Paris method. Both sets of casts were sent to a professional orthotic laboratory with a prescription filled out for an orthotic shell with a medium amount of arch fill, average heel cup depth, normal orthotic width (to the lateral border of the 5th metatarsal and bisection of the 1st metatarsal shaft) and a thickness of polypropylene which would behave in a semi-rigid behavior for the patient’s stated weight. A laboratory technician was instructed to randomly select one of the two pairs of negative casts and keep track of which casts were used without the knowledge of the principal investigator. In this way, a double blind study was established since neither the principal investigator nor the patient knew which casts were used to construct the foot orthotics.
Approximately 2-3 weeks following casting, the patient was dispensed a pair of functional foot orthoses and asked to walk around for a minimum of 10 minutes to gauge the comfort level of the orthotics. Each participant was asked to use one of 4 descriptive terms (very comfortable, comfortable, slightly uncomfortable or very uncomfortable) to describe the comfort level of 5 different regions on each foot orthosis corresponding to the heel region, medial arch, lateral arch, middle of the orthosis and distal edge. Patients were then sent home with standardized break-in instructions for the functional foot orthoses and returned to the clinic at intervals of 2 weeks and 4 weeks post-orthotic dispensal.
At each follow-up visit, patients were asked to fill out a data sheet gauging the level of symptoms and comfort level of the orthoses. The data was then compiled and saved in a spread sheet format and upon completion of the study, the laboratory technician was contacted in order to identify which patients belonged to which study group, the foam box or plaster of Paris casting technique.
The data was compiled and the two study groups separated by casting technique. An independent investigator (non-podiatrist) was contacted and asked to analyze the data to answer the following questions:
1. Does the negative casting technique (foam vs. plaster) make a difference in the ability of the orthotic device to reduce symptoms?
2. Does the negative casting technique (foam vs. plaster) make a difference in how comfortable the orthotic device feels to the patient?
The data was analyzed in a variety of methods such as the mean reduction of pain, Fischer exact test and Chi-square with T-tests. A simple comparison of the average reduction of pain after four weeks of orthotic therapy indicates that the plaster of Paris orthoses achieved a mean decrease of 82.43% of pain versus 61.14% reduction in pain with foam box cast orthoses, with a level of significance p< 0.01. However, further analysis of the data demonstrated that casting technique had no statistical difference in the reduction of pain in patients presenting with high levels of pain, but a significant advantage for plaster of Paris orthotics in reducing moderate amounts of pain.
The difference between the comfort levels of the orthoses from different casting techniques was also extremely interesting. No statistical difference was noted in the comfort level of any of the five regions studied (the heel, medial arch, lateral arch, middle of orthosis and distal edge) at the time the orthotic was dispensed. However, after one month of orthotic wear, the orthoses manufactured from plaster of Paris casts were statistically more comfortable in the medial longitudinal arch and the distal edge regions.
Another analysis performed on comfort level of the orthotic devices compared improvement of comfort level between the orthoses from the two casting techniques. In this analysis, only the medial longitudinal arch was statistically more improved in the plaster of Paris technique versus the foam box method.
The analysis of the data was fascinating in that both casting techniques were able to show some marked reduction in symptoms and reasonably comfortable orthoses. However, there were some statistical advantages of the plaster of Paris orthoses over the foam box devices. Further research needs to be encouraged and might include studying the differences between orthotic devices from plaster casts versus over-the-counter pre-fabricated devices and also against orthotics constructed from computer-digitized images of the foot.
The Evaluation of Cleated Shoes with the Adolescent Athlete in Soccer
John H. Walter Jr. DPM, MS, Temple University
School of Podiatric Medicine, Philadelphia, PA
Chairman and Professor,
Department of Orthopedics and Medicine
8th and Race Streets, Philadelphia, PA 19107
Gregory K. NG DPM 2nd yr. Podiatric Surgical Resident,
Parkview/City Ave Hospitals,
Tenet Health Systems
Philadelphia, PA 19124
Thirty-six children between the ages of eight and eleven were tested to determine if soccer cleats placed their feet in a dorsiflexed or “negative heel” position at midstance while running in cleated shoes. A comparison was made between non-cleated shoes and cleated shoes using both F-scan in-shoe sensor system (Tekscan INC., Boston MA), and videotape analysis. Negative heel position is afoot that is in a dorsiflexed position, relative to the lateral aspect of the heel and forefoot greater than ninety degrees during the stance phase of running while wearing cleated shoes. It is this dorsiflexed foot position that is responsible for increases in the amount of pressure placed upon the calcaneal epiphysis or secondary growth center of the calcaneus. In addition to the increased pressures placed on the calcaneal epiphysis a dorsiflexed foot position during the stance phase increases the amount of pull from the soft tissue attachments which is primarily from the tendo achilles and secondarily from the plantar fascia The study attempts to link the negative heel position to the high incidence of inflammation of the calcaneal growth center, or calcaneal apophysitis commonly found in the youth soccer population. Treatment options for calcaneal apophysitis are also discussed
A comparison was made between non-cleated shoes and cleated shoes using both F-scan in-shoe sensor system (Tekscan INC., Boston MA), and videotape analysis. When the foot is positioned in a dorsiflexed position greater than ninety degrees to the supporting surface during the stance phase of running, a negative heel position is created (figure 1). Thirty-six male test subjects between the ages of eight and eleven were tested in an effort to prove that the wearing of cleated shoes placed the foot of a young soccer player in a negative heel position more so than if wearing non-cleated shoes.
Soccer is one of if not the most popular sport in the world. Currently more children in the U.S. now play soccer than Little League Baseball. 1 Not only has there been an increase of young soccer athletes; there has been an increase in the frequency of play. During the 1990′s there has been an increasing trend of single sport youth athletes who train year round. Many young soccer players now participate in all four seasons of the year playing both indoors and outdoors. With the increase in the number of young athletes playing soccer and the increase in the amount of playing time, there has been, significant rise in the incidence of young players presenting with foot pain such as inflammation of the calcaneal epiphysis, more commonly known as Sever’s Disease (osteochondritis). Other common names for the calcaneal epiphysis are traction epiphysis or apophysis.
*This study was made possible from a grant from The American College of Foot and Ankle Orthopedics and Medicine and a soccer shoe donation from NIKE.
Three etiological factors which can lead to the inflammation of the calcaneal epiphysis are: increased pressure, increased pull, and overuse are the factors that cause an inflammation of the calcaneal epiphysis.2 A negative heel position would increase the direct pressure and tendinous pull, while the repetitive nature of soccer would introduce the third factor listed, overuse. Thus, the sport of soccer exposes young participants to three main factors that can lead to Sever’s disease.
Soccer shoe design has remained relatively unchanged when compared to other types of athletic shoe gear such as with running shoes (figure 2). Current designs in soccer cleats lack pressure absorption and motion control which can at times place the foot in an unstable position leading to injuries such as: stress fractures, sprains, strains, tibial fasciitis (shin splints), exertional compartment syndrome, ankle capsulitis/impingement, patelia-femoral dysfunction, and heel pain (figure 3). Lack of motion control, improper arch support can lead to skeletal misalignment leading to postural symptomatology such as medial/lateral knee pain, iliotibial hand syndrome, hip, and lower back pain. Prepubertal long-bone growth spurts often exceed the growth of muscles and tendons. Shortening of the triceps surae group, as a result of the rapid growth of the tibia, may diminish ankle dorsiflexion to less than 10 degrees, possibly creating a strain on the tendon especially at the area of its insertion (calcaneal secondary growth center). 3,4 Negative heel position created by the cleated shoe can increase the amount of heel cord pull on the calcaneal epiphysis, by dorsiflexing an ankle joint which may already be limited due to muscle contracture secondary to growth spurts. A combination of repetitive overuse through soccer practice and games, with the negative heel position created by the use of cleated shoes, place the young athlete at risk for developing not only calcaneal apophysitis but also tendinitis of the posterior heel cord (tendo Achilles), and plantar fasciitis.
Very few epidemiology studies to date have been done which look at the relationship between the use of cleated shoes and foot injuries sustained by young athletes. Micheli LJ, Fehlandt AF Jr., reviewed 724 cases of tendinitis or apophysitis that were diagnosed in 445 patients seen in the Sports Medicine Division at Boston Children’s Hospital between 1980 and 1990. Age of the patients ranged between 9-19 years. Of the 38 soccer injuries noted in boys dealing with tendiits or apophysitis, 18(47%) were diagnosed as calcaneal apophysitis, 9(24%) were diagnosed as Aehilles tendinitis, 4(11%) were diagnosed with tibialis posterior tendinits. A total of 82% were due to either calcaneal apophysitis or heel cord tendinitis. Of the 26 soccer injuries noted in girls dealing with tendinitis or apophysitis, 8(31%) were diagnosed as calcaneal apophysitis, 6(23%) were diagnosed as tibialis posterior tendinitis, 4(15%) were diagnosed as Achilles tendinitis. Results totaling 69% were due to either calcaneal apophysitis or heel cord tendinitis. According to Micheli and Fehlandt, both Sever’s disease and heel cord tendinitis make up the majority of youth soccer injuries resulting from either tendinitis or apophysitis (boys=42% girls=69%).
Methodology Frame by frame video analysis of 36 male test subjects was performed on soccer fields, to study the length of time for the test subjects to move from heel strike to heel lift while running in both cleated and non-cleated shoes. Freeze frame comparisons were also made of the same video to evaluate the dorsifiexed foot position in cleated shoes. Video was obtained of test subjects that ran past at a moderate running pace commonly seen in soccer play. F-scan pressures vs. time pedobaragraphs were taken of both cleated and non-cleated shoes (running shoes) to note pressure distribution while running. All test subjects were between the ages of eight and eleven, weighing from 75 to 110 lbs, and had standard biomechanical, gait, and postural exams performed.
Of the 36 test subjects, 11 were determined to have cavus or high arched foot types, 14 with rectus or normal foot types, and the remaining 11 with pes planus or low arched foot types. All test subjects had adequate ranges of motion at the subtalar joint (STh, midtarsal joint (MTJ), first metatarsal phalangeal joint, and ankle joint with the exception of 5 subjects who had limited ankle joint dorsiflexion. All testing was performed on outdoor soccer fields. For consistency the same researcher performed the biomechanical exams. 187 questionnaires were gathered noting foot and leg pain among young soccer players between the ages of eight to thirteen years old. (figure 4)
When compared to non cleated shoes, frame by frame video analysis revealed that 23 test subjects took a longer period of time to move from heel strike to heel lift while running in cleated shoes. (Figure 5). Freeze frame analysis demonstrated a more dorsiflexed foot position during full foot contact (an average of 7 degrees) during stance phase while running in cleated shoes in 26 subjects (figures 6a, 6b). F-scan sensor data was able to capture a characteristic plantar pressure “foot print” of very highly focused pressures in the rearfoot as well as a rough transition from rearfoot to forefoot while running in cleated shoes (figures 7a, 7b). A characteristic footprint was reproducible in 21 of the 36 test subjects. It should be noted that the “foot print” was most reproducible in test subjects who had pes planus foot types with limited ankle dorsiflexion. The “foot print” was least reproducible in test subjects with cavus foot types. The average plantar pressure was noted to be in the 3O-psi(pounds per square inch) range in non-cleated shoes, and in the 70 psi range wearing cleated shoes.
See also figures 8a, 8b.
Data gathered from both the video and F-scan analysis between running shoes and soccer cleats confirms the negative heel hypothesis. It is this negative heel that plays a crucial role in the high percentages of young soccer players who develop Sever’s disease, by not only increasing the direct pressure placed on the calcaneal epiphysis, but by also increasing the traction on the epiphysis primarily via the tendo achilles. In addition to the increased pull and pressure on the calcaneal epiphysis, the repetitive nature of the sport, constant running in cleated shoes, must also be considered as a factor. If one is able to decrease the amount of negative heel (via. Heel lifts, orthotic management, soccer shoe redesign, etc…), then one can decrease the tendency for young soccer players to develop heel pain and or posterior heel cord tendinitis.
Treatment options for mild heel pain or calcaneal apophysitis should include 1/8″ to Â¼” heel lifts in both shoes, elastic ankle bracing, ice massage before, during and after play, and warm up stretching exercises. If the pain persists or increases than turf or non-cleated shoes should be worn with heel lifts, bracing, and a reduction in both playing and training time should be implemented. When the symptoms persist and the player is noticeably limping from the pain, discontinuation of play is recommended with immobilization of the foot and anide in a short leg walking cast, cast boot, or soft cast. The player should be non-weight bearing or partial weight bearing (toe touch to off load heel) for four to six weeks ambulating with the aid of crutches.
It is important to make an accurate diagnosis of calcaneal apophysitis and rule out such things as juvenile rheumatoid arthritis bone cyst, tarsal coalitions or peroneal spastic flatfoot, foreign body, etc…
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