MEDICAL COMMUNITY

Jack is a 40-years-old firefighter.  Trim and athletic, Jack enjoys running as his regular source of exercise.  One day, after completing a half marathon, he notice right medial knee pain and swelling that become progressively more severe.  He had no prior history of knee pain or injury before this episode.   After an orthopedic consultation and negative imaging studies, he was referred to my office for physical therapy; his physician knew me as a running coach and physical therapist.  I first looked at Jack's exercise program.  I found that he properly trained for the race, and had been quite accustomed to events like this.  I then looked closely at Jack running shoes.

ROUTINE CHECK-UP
Many times,when an otherwise athletic, healthy person experiences an overuse injury with no apparent reason, I look at the routine the athlete practices.  The checklist includes:

• The athlete has a has a good stretching routine in place in conjunction with each running session.
• the weekly mileage is consistent and appropriate with the fitness level and goal of the runner.
• The patient cross-trains appropriately with the fitness level and goals of the runner.

In addition, as part of a complete history and physical examination of runner with overuse injuries, it is important to thoroughly evaluate the athlete's shoes.

MINOR DEFECT, MAJOR PROBLEM
In examining Jack's running shoes. I notice the right heel counter was severely twisted inward,  which caused Jack's foot to roll-in excessively.  Upon closer inspection. I discovered that the heel counter was glued improperly. This caused Jack to overpronate in his anti-pronation caused him to repeatedly twist his knee, which resulted in injury.

In recent years, I've documented a growing number of injuries due to defective shoes.

Knowing how to check a runner's shoe for manufacturer's defects can save your patient time and money, and can prevent needless injuries.

Be sure the shoe is securely glued together. To test it, hold the shoe and try to pull the upper from the lower of the shoe. If it separates at all, this will weaken the shoe's support.

The upper part of the shoe should be glued straight into the sole. To test this, use a goniometer to measure a 90-degree angle between center of the heel counter, and a horizontal line through the middle of the sole from the back on a level surface, the whole upper should appear even and should not pitch to the right or left.

A brand new shoe that pitches medially or laterally could cause injuries, especially if there is a large asymmetry between both shoe.

The sole of the shoe should be level to the surface on which the sole is resting.   To test, measure the medial and lateral vertical distance of the heel, compare the sides of the same shoe, and compare right and left for symmetry.  An asymmetry of two millimeters can pitch the shoe in or out significantly.

Check the shoe on a level surface to make sure they do not roll excessively inward or outward.  To test, apply a medial and then lateral force to both the right and left shoe to see if they rock inward or outward.  Check for asymmetry from side to side.   The shoes should remain even and not roll.  If they are new and roll, they will not stop the foot from excessively rolling, and injury could result.

Air pockets and gel pockets must be inflated evenly.  To test, push on air pockets on the outside medially to laterally, and laterally to medially to check for symmetry.  Push down into the air pockets both medially and laterally from the top of the heel counter, looking for a symmetrical loss of height in the pocket.  this causes the shoe to collapse, and the leg to roll when the foot hits the ground.

A good running shoe lasts 300 to 500 miles.  Mileage can be less if the shoe gets wet from running in the rain, or even running on a treadmill in a warm gym.  The average runner who trains 25 miles a week in an appropriate training shoe can expect to have a shoe life of 12 to 20 weeks.

Special care should be taken with a patient who is a marathon runner.  Their mileage increases dramatically while they're  training for a peak race.  It's not unusual for manufacturers to suddenly discontinue shoe models, and a shoe your patient is accustomed to may be unavailable for the big race.  I suggest that patients buy an extra pair before the long training program, put on 40 to 50 dry miles on the shoes, and put them away in the closet.  That way they'll be broken in, but fresh for the big race, which will also help prevent injuries.

As medical professionals, we must realize that abnormal shoe mechanics are one of many reasons for running overuse injuries.

As for Jack and his defective running shoe: He returned his shoe to the store where he purchase them and was given a non defective shoe of the same model.  I treated him for four weeks, and by the end of his treatment, he was able to run without knee pain.   On discharge, I reminded him to look closely before he bought his next pair of running shoes.

HOW TO CHECK FOR MANUFACTURER'S DEFECTS Section and components of an athletic shoe. The upper shoe is separating from the midsole when testing is performed to pull these two parts of the shoe apart.  The outsole stays intact with the midsole. A) Dotted lines shoes a 90 degree angle formed between the center of the heel counter and a horizontal line through the middle of the midsole of the sole. B) Dotted lines shoe the right, outward lean of the upper shoe because it is glued into the midsole at an outside angle. Inside (a) and outside (b) vertical distances are equal on the left shoe, demonstrating that the left shoe sole is level. B) The inside (c) vertical distance is larger than the outside (d) vertical distance on the right shoe, demonstrating that the right shoe is tilted in an outside direction. A) A downward, inwardly directed force does rock the left shoe inward. B) A downward, inwardly directed force does rock the left shoe inward. A force if directed outwardly with the thumb over the inside air / gel pocket to check for symmetry of inflation. A) A downward, outward pressure does not cause loss of height in the outside air pocket in the left shoe.  B) A downward, inside pressure causes the inside air pocket to lose height and collapse inwardly on the right shoe.

• The shoe should be glued together securely. Test this by holding the shoe and trying to pull the upper part of the shoe away from the midsole, and the midsole from the outsole (Figure 6). If it separates at all, this will weaken the shoe's support.
• The upper part of the shoe should be glued straight into the sole. Test this by putting the shoe in a level surface and inspect the back of the shoe. The whole upper part of the shoe should appear even and should not lean to the right (Figure 7B) or left. A brand new shoe that leans medially or laterally could cause injuries especially if there is a large asymmetry between each shoe of a pair.
• The sole of the shoe whould be level to the surface on which the shoe is resting. Test this by looking to see that the inside and outside of the heel is even to a level surface (Figure 8A and B). Compare each shoe and from the right to the left shoe for symmetry. An asymmetry of two millimeters can tilt the shoe in or out significantly.
• The shoes should not roll excessively inward and/or outward when resting on a level surface. Test this by applying a downward, inside and then a downward, outside force to both the right and left shoe to see if they rock inward and/or outward (Figure 9A and B). Check for asymmetry from side to side within each shoe. The shoes should remain even and not roll. If they are new and roll, they will not stop the foot from rolling excessively when worn, and could result in injury.
• Air pockets and gel pockets must be inflated evenly. Test this by pushing on the sides of the air pockets inside to outside, and outside to inside to check for symmetry (Figure 10). Push down into the air pockets both inward and outwardly from the top of the heel counter, looking for symmetrical loss of height in the pocket (Figure 11A and B). If the pockets are inflated unevenly, this causes the shoe to collapse unevenly, and the foot to roll when it hits the ground.

Bruce R. Wilk, PT OCS'
Karen L. Fisher, MS, PTI
William Gutierrez, MS, PT, OCS, ATC1

Study Design: Case study of a patient who developed plantar fasciitis after completing a triathlon.

Objectives: To describe the factors contributing to the injury, describe the rehabilitation process, including the analysis of defective athletic shoe construction, and report the clinical outcome.

Background: Plantar fasciitis has been found to be a common overuse injury in runners.  Studies that describe causative factors of this syndrome have not documented the possible influence of faulty athletic shoe construction on the symptoms of plantar fasciitis.

Methods and Measures: The patient was a 40-year-old male triathlete who was followed up for an initial evaluation and at weekly intervals up to discharge 4 weeks after injury and at I month following discharge. Perceived heel pain, ankle strength, and range of motion were the primary outcome measures. Shoe construction was evaluated to assess the integrity of shoe manufacture and wear of materials by visual inspection of how shoe parts were glued together, if shoe parts were assembled with proper relationship to each other, if the shoe sole was level when resting on a level surface, and if the sole allowed unstable motion.

Results: The patient appeared to have a classic case of plantar fasciitis with a primary symptom of heel pain at the calcaneal origin of the plantar fascia. On initial evaluation, right heel pain was a 9 of 10, plantar flexion strength was a 3+/5, and ankle clorsiflexion motion was 10'. One month after discharge, perceived heel pain was 0, plantar flexion strength was 5/5, and clorsiflexion motion was 15' and equal to the uninvolved extremity.

The right running shoe construction deficit was a heel counter that was glued into the shoe at an inward leaning angle, resulting in a greater medial tilt of the heel counter compared with the left shoe. The patient was taught how to examine the integrity of shoe manufacture and purchased a new pair of sound running shoes.

Conclusions: A running shoe manufacturing defect was found that possibly contributed to the development of plantar fasciitis. Assessing athletic shoe construction may prevent lower extremity overuse injuries. J Orthop Sports Phys Ther 2000,30:21-3 1.

Key Words: defective athletic footwear, plantar ligament inflammatory syndrome, running Physical therapists frequently treat patients with injuries sustained from running. 

Often these pathologic conditions stem from poor skeletal alignment in the pelvis and lower extremity. According to Gross"' and others, L3, 12,13, 16,2'1 musculoskeletal pathologic conditions may be exacerbated by pelvic and lower limb malalignments or biomechanical imbalances caused by training techniques, footwear, running style, environmental terrain, and sport-specific athletic conditioning. Physical therapists routinely inspect shoes and wear patterns in patients who develop pelvic and lower limb musculoskeletal pathologic conditions. In our clinic, examination of athletic shoe construction (in patients with common lower extremity overuse injuries) has revealed manufacturing defects in shoes that were used at the time of injury. Although the cause of an overuse injury is multifactorial, a review of the literature did not reveal any studies of defective athletic shoe construction as a contributing source of common lower extremity overuse injuries.

This case report is based on the clinical observation of a patient who developed plantar fasciitis while wearing a pair of running

TABLE 1. The patient's training schedule 8 weeks before the race.  

shoes that were found to have a manufacturing defect. The study identifies the musculoskeletal pathologic structure and looks at the possible factors that contributed to this injury~ The patient's specific treatment plan is described, and the patient's response to the treatment is delineated. Suggestions are made for patient education in proper shoe selection and foot support. Clinical guidelines were created and are presented to teach patients how to assess the quality of athletic shoe construction.

METHODS AND MEASURES

Subject  
A 40-year-old male triathlete with a diagnosis of plantar fasciitis was referred to physical therapy by his family physician. The patient complained of the onset of heel pain in his right foot after completing a half-ironman triathlon, which consists of a 2-km swim, a 90-km bike ride, and a 21-km run. The patient was an experienced triathlete, and he described a well-rounded training program. His regimen included a daily flexibility routine and a biweekly strength training routine. Biking and running workouts were performed over bridges to simulate hill training, because the patient lived in a flat environment and the race course was hilly.  

Interview Data 
 The patient was familiar with the race course, because he had trained and competed on it previously. Table I shows the patient's training schedule 8 weeks before the race. The patient used the same brand and model of running shoes for more than 2 years, with replacement of worn shoes every 480-800 km. The patient felt the weather conditions during the race were favorable, since it had been cool and overcast, even though it rained for a short period at the beginning of the run. Several hours after the race, the patient noticed a gradual onset of right inferomedial heel pain, which presented as a dull, constant ache. The day after the race, the patient noticed sharper pain in the same location on the right foot, especialh when taking the first several steps in the morning. These symptoms were severe enough to cause the patient to limp while walking and made it impossible to run. There was no history of heel pain. Rest from weight-bearing activities and icing helped to alleviate the pain. The patient also noted that initially he had minor muscle soreness in the right proximal calf.

Physical Examination
Two days after the race, the patient was seen for an initial physical therapy evaluation. One clinician completed the patient examination. The right lower extremity plantar fascia and soft tissues were examined with palm and fingertip palpation. Varying pressures from light touch to deep pressure were used to determine the irritability of the plantar fascia and associated tissues and the patient's perceived pain. With the toes maintained in passive extension, firm palpation pressure was exerted on the medial border of the plantar fascia along the longitudinal arch. This palpation procedure was repeated with the patient actively dorsiflexing the right ankle and extending the great toe.

The patient's lower extremity alignment was evaluated by measuring the subtalarjoint angle in standing, using a goniometer. The therapist measured the angle created by a line bisecting the posterior aspect of the distal third of the lower leg and a line bisecting the posterior aspect of the rear foot."' There were 5' of calcaneal eversion bilaterally.

Further musculoskeletal evaluation of the right lower extremity included gait analysis, manual muscle testing, and flexibility testing of the gastrocnemius muscle. The patient's gait was visually examined, with the patient walking at a moderate pace within his pain tolerance. Gait deviations were compared with the conventional components of a normal gait cycle. Manual muscle testing was completed using the iraditional manual muscle testing positions and scale, according to Daniels and Worthingham's manual muscle testing text. 14 Gastrocnemius muscle flexibility testing was completed by measuring the angle of ankle dorsiflexion with a goniometer, while passively 

FIGURE 1. Sections And Components Of A Running Shoe

dorsiflexing the non-weight-bearing ankle from a subtalar neutral position with the knee in 0' extension. The end feel of the dorsiflexion range of motion was noted. An x-ray report revealed no evidence of anatomic abnormalities, stress fractures, bonv tumors, osteophytes, or degenerative joint disease.

Shoe evaluation involved visual inspection of shoe parts as shown in Figure l.',9,1',21 The shoe was assessed for the integrity of construction and the wear of the shoe materials.

The patient's heel pain and deficits were found exclusively on the right lower extremity. The patient appeared to have a classic case of plantar fasciitis, with a primary symptom of heel pain at the calcaneal origin of the plantar fascia.

Outcome Measures
The patient perceived his right heel pain as intense by rating the pain as a 9 on a subjective 0 to 10 visual analog scale (where 0 indicates the absence of pain and 10 indicates the maximum pain). Moderate pressure fingertip palpation over the right inferomedial calcaneus elicited a verbal pain response and limb withdrawal due to pain. With the toes maintained in extension passively, firm pressure to the medial border of the plantar fascia elicited the previous pain response. In bare feet, the patient's standing posture revealed ankle pronation on both lower extremities. Using a goniometer, 5' of calcaneal eversion were measured during static single-limb support on each lower extremity.

Musculoskeletal evaluation of the right lower extremity revealed the following. First, the patient displayed an antalgic gait pattern, where the transfer of body weight was executed with a nearly flat foot, resulting in a shortened stance of the right lower extremity due to decreased heel strike and push-off phases. Second, manual muscle testing produced heel pain and showed impaired gastrocnernius and 

FIGURE 2. In this posterior view, gray arrows (A and B) point to the mild inward lean of the training (T) shoe heel counters.  The upper, outside borders of the heel counters show an inward bending of the lateral portion of the heel counter due to the stress from the repetitive pronation force during running.

soleus strength; the patient was able to complete 5 repetitions of full-range heel raises, representing strength in the 3+/5 range on the standard manual muscle testing scale. 14 Third, a limitation in the passive (non-weight-bearing) clorsiflexion of the ankle from a subtalar neutral position (with 0' knee extension) revealed a decreased flexibility of the gastrocnemius muscle; right ankle clorsiflexion measured 10' compared with 15' on the left ankle; there was a firm end feel to the motion, and the patient report7 ed feeling a pulling sensation in the right calf.

The stabilizing components of the patient's training and racing shoes included a visible rear foot grid system with heel counter reinforcement and a compression-molded midsole of ethylenevinyl acetate foam and dual-density polyure than e. Both pairs of shoes showed posterolateral heel wear. Each ofthe training shoes showed a mild inward lean of the heel counter (Figure 2). According to the patient, the training shoes had approximately 480 km of wear, and the racing shoes had approximately 48 kmi of wear. Examination of the racing shoes revealed the right shoe heel counter had a visibly larger inward tilt compared with the left racing shoe (Figure 3) and the training shoes (Figure 2). The right racing shoe heel counter was glued into the shoe at an angle that we thought could have caused excessive inward rolling of the right foot.

Treatment
The goals of treatment for plantar fasciitis were to decrease inflammation; increase flexibility and strength; improve functional agility, running skills, and conditioning; return gradually to a training schedule; and educate the patient about the components of sound athletic shoe construction.

Figure 3.  A, In this posterior view, a clear arrow points to the left racing (R) Show heel counter. B, A black arrow points to the visible inward deformity of the right racing (R) shoe heel counter that is glued in at a perpendicular angle, wheras the shoe in B has the heel counter that is glued in at a slightly medial angle.

Treatment to decrease inflammation included soft tissue mobilization and deep friction massage of the plantar fascia in a stretched position (ie, ankle dorsiflexion). The patient rolled his foot with a firm pressure on a 3/4-in-diameter wooden dowel rod for 5 minutes daily. The patient also received 8 ultrasound treatments to the right plantar fascia at an intensity of 1.0 W/CM2, continuous wave frequency of 1.0 MHz, for 5 minutes. A cold pack was applied daily to the bottom of the right foot for 20 minutes. 

The patient performed 20 minutes of stretching exercises daily for the right lower extremity as part of his home exercise program. Physical therapy sessions included passive and active assistive stretches that emphasized increasing the flexibility of the plantar fascia and the posterior lower extremity musculature (ie, piriformis, hamstring, iliotibial band, gastrocnemius and soleus, and both the intrinsic and extrinsictoe flexor musculature). The patient performed calfstretches leaning toward a wall in a weight-bearing position by moving the tibia anteriorly over the foot, with the knee flexed and with the knee extended.

The patient also stretched off the edge of a step by keeping the toes pointing slightly inward with the forefoot weight-bearing on the step. The patient then dropped the heel downward slowly, while preventing the foot from pronating.

A progressive rehabilitation protocol was implemented (Table 2). Strengthening exercises were performed on alternate days in series of 3 sets to temporary muscle fatigue (ie, loss of form or ability to push the resistance through the full range of motion or substitution of a stronger muscle group for a weaker muscle group). The patient continued a swimming program and biking outside his treatment sessions. As soon as the patient was pain-free during activity in the morning, he began the walking program described in week I of the rehabilitation protocol (Table 2). Balance, conditioning, and agility skills were also addressed in a home program that was consistent with the progression of the treatment plan.

The patient was educated about the components of sound athletic shoe construction. The following guidelines were developed to teach the patient how to look for sound shoe construction:

• The shoe should be glued together securely. Test this by holding the shoe and trying to pull the tipper part of the shoe away from the midsole and the midsole from the outsole (Figure 4).

• The tipper part of the shoe should be glued straight into the sole. Test this by using a gomometer to measure a 90' angle. Place the vertical arm (of the goniometer) along the center of the posterior heel counter and the horizontal arm parallel to the surface on which the shoe is resting (Figure 5A). As you view the shoe from the back on a level surface, the whole upper part of the shoe should appear even. Figure 5B shows the upper shoe leaning to the right.

• The sole of the shoe should be level to the surface on which the shoe is resting. Test this by meaSuring the medial and lateral vertical distance of the posterior sole on the heel of each shoe. With a tape measure or a ruler, measure the distance from the top edge of the posterior sole to the surface on which the shoe is resting (Figure 6A and B). Compare these measurements within each shoe.  

• The shoes should not roll excessively inward or outward when resting on a level surface. Test this by applying a downward medial and then a downward lateral force to both the right and left shoe to see if they rock inward or outward (Figure 7A and B).  

• Air pockets and gel pockets must be inflated evenly. Test this by pushing a thumb into the air and gel pockets to check for firmness of inflation (Figure 8). Also, push with a medially directed downward force from the top of the shoe upper over the heel counter. Repeat this test with a laterally directed downward force (Figure 9A and B). Look for a loss of height in the pocket.  

Results  
The patient was seen for treatment 2 times a week for 4 weeks. Heel pain during standing and walking and morning foot pain were monitored to determine progression of activity and treatment.

By the end of the first week of treatment, the patient's subjective pain level was 6 of 10 to deep palpation of the calcaneal attachment and medial border of the plantar fascia. The patient no longer had

Week I  

• Ankle and foot strengthening exercises in non-weight-bearing positions with light elastic bands  

• Marble pick ups and towel pushing and pulling for intrinsic foot muscle strengthening  

• Double-limb heel raises on ankle board  

• Single-limb balance exercises on 3-in foam  

• Lower-body ergometer 30 minutes at 70-80% maximum heart rate at a pedaling cadence of 80-100 revolutions per minute  

• Functional agility activities of forward and backward and lateral walking drills

• Home exercise program of walking for I hour 4 times per week

Week 2  

• Single-limb heel raises from a flat surface  

• Heel raises from the edge of a step beginning with both limbs and progressing to single limb  

• Continue single-limb balance exercises on 3-in foam  

• Lower-body ergometer 30 minutes as in previous week  

• Functional agility activities as in week I with resistive tubing  

• Home exercise program of walking for 20 minutes, jogging 2 minutes, and walking 3 minutes for a 20-minute period, ending with walking for 20 minutes, for a total time of 1 hour 4 times per week

Week 3  

• Right lower extremity weight-hearing exercises using elastic tubing resistance around the left ankle to resist hip flexion, extension, abduction, and adduction patterns to stress the muscles of the right foot and calf  

• Single-limb balance exercises emphasizing posture assumed during running  

• Lower-body ergometer 30 minutes as in week I  

• Functional agility activities of forward and backward and lateral jogging drills  

• Home exercise program of 20 minutes walking and 20 minutes jogging, ending with 20 minutes walking, for a total time of I hour 4 times per week

Week 4

• Lower-body weight-bearing exercises on pulley system with an adjustable weight stack 

• Lower-body ergometer 30 minutes as in week I  

• Running drills (drills performed at a slow jogging pace for 46 m)

a.    High kicks-exaggerate kicking behind by kicking the heel of each foot back and upward tapping the buttock with each step taken to work on increasing stride length and enhancing the follow through of each leg

b.    High knee turnovers-exaggerate lifting each knee upward in a marching fashion without extending the knee or throwing the foot forward to work on keeping knees high during running to prevent a shuffling pattern

c.    Hands on head emphasizing a neutral posture-run with hands placed on the top of the head to exaggerate an upright posture to work on preventing a forward lean and forward posture, emphasizing forward progression from the pelvis

d. Exaggerated trunk twisting and correction-begin with exaggerated (contralaterah trunk rotation with the forward progression of each leg and slowly correct to smooth, efficient control of trunk motion to work on conserving energy by not allowing unnecessary trunk motion to occur

e.      Exaggerated arm swings and correction-begin with exaggerated (contralateral) arm swinging with each step taken and slowly correct to smooth, efficient arm swing being sure not to allow arms to cross midline to work on efficiency of arm use for enhancing forward progression

f.      Bounding-leap with large strides exaggerating the push-off of each foot to work on the power of pushing off with each lower extremity

• Home exercise program of 10 minutes walking and 40 minutes jogging, ending with 10 minutes walking, for a total time of 1 hour 4 times per week

FIGURE 4. The upper shoe is separating from the midsole when testing is performed to pull these 2 parts of the shoe apart.  The outsole stays intact with the midsole

morning pain with initial weight-bearing and no complaints of calf tightness.  

After learning how to evaluate shoe construction, the patient purchased a new pair of the same model of running shoes he had worn for the half-ironman race. He brought the shoes to a treatment session, and there appeared to be no visible manufacturing defects. He started to use the new running shoes and was able to walk for I hour with a normal gait pattern. He could perform 10 single-limb heel raises before showing signs of fatigue. After week 2 of rehabilitation, the patient's pain level dropped to a 4 during deep palpation and was 1-2 at the end of a busy day. His muscle strength was in the good manual muscle testing range. He was tolerating 20 minutes of combined jogging and walking, with 40 minutes of walking. By week 3 of rehabilitation, the patient had a 1-2 pain level to palpation and no pain with active or passive dorsiflexion or at rest. The flexibility of  

FIGURE 5. A dotted lines show a 90° angle, measured with a goniometer formed by the vertical center of the posterior left shoe heel counter and a horizontal line that is parallel to the resting surface. B. Vertical and horizontal doted lines show the outward lean of the heel counter of the right show because it is glued into the midsole with a lateral glue

FIGURE 7. A, A downward medially, directed force does not rock the left shoe inward. B, A downward, medially directed force does rock the right shoe inward.

the right gastrocnemius muscle was equal to the left, and he could perform 16 heel raises before showing signs of fatigue. He was able to tolerate 20 minutes of jogging in his 60-minute walking program. At the end of the fourth week, the patient was ready for discharge from physical therapy. He reported a 0-1 pain level to deep palpation of the plantar fascia and no pain at rest. He was able to run 40 minutes without pain or gait deviation. The plantar flexor strength of the right lower extremity was 4+/5 (ie, good plus), and the flexibility was within normal limits. At a Imonth follow-up visit, the patient was asymptomatic and progressing his running program in intensity and time. The patient displayed equal flexibility of the right lower extremity to the left lower extremity of 15' ankle dorsiflexion, with 0' knee 

FIGURE 6. The lateral (a) and medial (b) vertical heights of the posterior sole are equal on the left shoe, demonstrating that the left shoe sole is level B, The medical (c) vertical of the posterior sole of the right shoe is larger than the lateral (d) vertical height, demonstrating that the right show sole is not level

joint extension- He had no complaint of heel pain with active or passive dorsiflexion and was able to complete 20 heel raises through full range of motion against gravity, representing gastrocnemius strength within normal limits. The patient was able to walk and run with a pain-free, normal gait pattern.  

DISCUSSION  
Pronation occurs at the subtalarjoint during the stance phase of the gait cycle. Midtarsaljoint (ie, talonavicular and calcaneal cuboid) motion results and the medial arch flattens. The talus adducts, plantar flexes, and moves anteriorly with respect to the calcaneus. The calcaneus everts, and forefoot vaIgus occurs. In the lower leg, the tibia internally rotates and migrates anteriorly to maintain ankle joint congruency. Pronation provides for shock absorption and adaptation to the terrain under the foot. When this motion is excessive, a torsional force is created and  

FIGURE 8. A force is directed into the inside air and gel pockets, with the thumb, to check for firmness and symmetry of inflation
	FIGURE 9. A, A downward force on the lateral aspect of the left shoe (depicted by black arrows) demonstrates compression but  no loss of height in the outside air pocket, B, A downward force on the medial aspect of the right shoe (depicted by the black arrows) causes inside air pocket to lose height and collapse.

stretches the plantar fascia, leading to inflammation and pain. ^{7 , 12 , 15, 19,20}

Plantar fasciitis is characterized by inflammation or degeneration of the plantar fascia, particularly at the calcaneal attachment.²² Excessive pronation of the subtalar joint beyond the normal range of approximatelv 9.4' is the primary cause of plantar fasciltis.¹¹ Anatomic causes of abnormal pronation include abnormalities secondary to neuromuscular disease, congenital pes planus, and acquired deformities. Excessive pronation can be acquired from limited flexibility of the gastrocnernius and soleus muscle groups, resulting in a shortened Achilles tendon.^{5, 15}  

We feel that this case study reveals that a defectiveIv manufactured running shoe may have promoted the development of plantar fasciitis in the presence of other contributing factors. There are ample studies that record potential sources that might cause plantar fasciitis. ^{2,4.6,8, 12, 13. 1 G. 17} In this case, the patient had a predisposition to pronate, which he compensated for by wearing a running shoe designed to enhance foot stability. The running mileage on t e racing shoes was low and fell within the 480-800 kin of wear guideline used for replacing worn-out shoes." Although the patient's training program seemed well rounded, the demands of a hilly race course and the accumulation of long distance workouts must be considered as potential causes of this overuse injury. Also, the influence of demands on the gastrocnemius and soleus muscles are complicated in a sporting event that involves 3 different activities (ie, swimming, biking, and running). There is the potential for the calf muscles to tighten during the swim and bike ride to produce increased pronation during the run. 2 The defective running shoe may have facilitated the patient's pronation because the heel counter was canted inward. If the rainy weather conditions caused the shoe to stretch and become more unstable, the pronation deviation may have worsened. Therefore, the defective shoe may have added to the combination of factors that could cause plantar fasciitis because it might not have properly stabilized the right foot.  

Because today's running shoes tend to be somewhat customized, it is beneficial for patients to know their foot type and running style to purchase shoes designed to support their needs. Various sources have documented the appropriate running shoe design and selection related to lower extremity anatomy and biomechanics. ^{1,9, 13,17, 1S,21,23}  

We felt it was important for patients to know how to avoid buying defective athletic shoes. The guidelines developed to teach the patient in this case study how to look for sound shoe construction were made available to our patients and local athletic community. 

CONCLUSION  
This case study describes a patient with heel pain and plantar fasciitis after completing a triathlon. We feel this case identifies faulty running shoe construction as a factor that contributed to the development of plantar fasciitis. Lower extremity overuse running injuries usually arise from multiple sources. The type of running shoe worn by an athlete can be an important factor in the prevention and treatment of overuse injuries.^1,13,18,23 Shoes that are appropriate and compensate for a biomechanical deviation may not prevent injury if they are manufactured with a defect. An increased awareness of the need to assess athletic shoe construction may potentially prevent an athlete from using a defective shoe that might contribute to ankle injury.  

ACKNOWLEDGMENTS  
We thank Willesley Chin for his assistance with our iterature search and Ann Carre for the original drawings she created.  

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9. Frey C. Helping the athletic woman find a shoe that fits. J Musculoskel Med. 1998;15(3):35-45.

10. Gross MT Lower quarter screening for skeletal malalignment-suggestions for orthotics and shoewear. J Orthop Sports Phys Ther. 1995;21:389-405.

11. Hall SJ, Messier SP. Biomechanics of fitness exercises. in: Durstine JL, King AC, Painter PL, Roitman JL, Zwiren LD, eds. American College of Sports Medicine's Resource Manual for Guidelines for Exercise Testing and Prescription. 2nd ed. Indianapolis, Ind: American College of Sports Medicine, Lea & Febiger; 1993:38-47.

12. Heil B. Lower limb biornechanics related to running in P1, ;-fl-n      1992478:400-406.iels and Worthingham's Muscle Testing. Techniques of Manual Examination. 6th ed. Philadelphia, Pa: WB Saunders Co; 1995.

13. Hunt GC, ed. Physical Therapy of the Foot and Ankle. New York, NY: Churchill Livingstone Inc; 1988.

14. James SL, Bates BT, Osternig LR. Injuries to runners. Am J Sports Med. 1978;6:40-50.

15. Martin DR. How to steer patients toward the right sport shoe. Physician Sportsmed. 1997;25(9):138-144.  

16. McPoil TG. Footwear. Phys Ther. 1988;68:1857-1865.  

17. Novacheck TF. The biornechanics of running and sprinting. In: Guten GN, ed. Running Injuries. Philadelphia, Pa: WB Saunders Co; 1997:4-19.  

18. Perry J. Gait Analysis: Normal and Pathological. Thorofare, NJ: Slack Inc; 1992:51-87.  

19. Pink MM, Jobe FW. The foot/shoe interface. In: Guten GN, ed. Running Injuries. Philadelphia, Pa: WB Saunders Co; 1997:20-29.  

20. Roy S. How I manage plantar fasciitis. Physician Sports jur es. ys      py-  med. 1983,-11:127-131.  

21. Heil B. Running shoe design and selection related to low- 23. Stacoff A, Denoth J, Kaelin X, Stuessi E. Running injuries er limb biomechanics. Physiotherapy. 1992;78:406-412.  and shoe construction: some possible relationships. Intj  

22. Hislop HJ, Montgomery J, Connelly B (contributor). Dan-      Sport Biomech. 1988;4:342-357. 57.  

By Bruce Wilk, PT OCS  
William Gutierrez, PT, OCS, ATC  

Medical specialists routinely treat running injuries and are familiar with the etiology of their pathologies, They regulariv assess running technique, musculoskeletal alignment, and shoe wear when evaluating an injured runner. However, we have noticed that further inspection of the running shoes revealed an alarming finding. We have found an increasing incidence of manufacturing defects that correlate directly as causative factors in patients' injuries. These findings demonstrate a need for clinicians to become aware of the possibility that the patient's shoes may be an underlying cause of injury, in conjunction with other more typically recognized biontechanical malalignment issues.  

While most sports medicine specialists recognize the need for high quality athletic equipment (footwear included), it should be noted that defects in running shoes (i.e. crooked heel counters, loosely glued midsoles, under-inflated shock absorbing pockets etc.) are not unusual. These defects have been overlooked by the general population and have the potential to cause an injury, or aggravate an already existing injury.  

Shoe design and wear patterns are routinely examined by clinicians to ensure that proper support is being provided for the athlete's foot. A natural extension of this routine procedure is to check the quality of the shoe's construction for any possible defects which may relate to the patient's musculoskeletal condition.

This paper will describe how running shoes with manufacturing defects or excessive mileage can contribute to, or be potentially responsible for, a variety of musculoskeletal complaints. We will also describe how running shoe design can influence the prevention and treatment of lower limb overuse running injuries(l). In order to prevent recurring injury or further injury, recommendations will be made regarding how to check existing shoes as well as new shoes, for defects prior to purchase.  

Typical Runners' Injuries
Running shoes are usually selected to provide support, and counteract biomechanical deformities or deficiencies in the foot. Despite this, injuries such as shin splints, patellar tendonitis, and iliotibial band friction syndrome commonly plague runners. The shoe itself may often be the cause of the runner's problem. For instance, during the stance phase, a shoe that tilts medially due to uneven wear will have a tendency to cause the foot to pronate excessively. Converselv, if a shoe tilts laterally, it may prevent pronation and prolong supination. This may lead to stress fractures in the foot or leg as well as anterior knee pain.

In order to demonstrate how defective shoe construction can cause running injuries, the patient's running mechanics, lower limb musculoskeletal alignment, and shoe design and construction must be evaluated.

Biomechanics of Running  
The gait cycle during running consists of a stance phase and a swing phase. The stance phase constitutes 60% of the gait cycle. Running is distinguished from walking by the flight phase: the period when both feet are off the ground. During running, the lower limbs absorbs 1.6 to 2.3 times the body weight as speed increases from an 8:56 minute mile to a 5:22 minute mile(2). Cavanagh, and coworkers, found that as running speed increases, peak forces of 2.5 to 3 times bodv weight are generated at heel strike(3). During a marathon, the body experiences over 25,000 heel strike impacts(4). This amounts to a tremendous load on the lower limbs. As a result most, if not all, running injuries occur during the stance phase(5).  

The stance phase consists of heel strike, mid-stance, and push off. At heel strike the foot initially contacts the ground in a supinated position. As the foot continues to make contact with the ground during mid-stance, it pronates to absorb shock; minimizing ground reaction forces. The flattening of the foot that occurs during pronation consists of subtalar joint eversion, forefoot abduction, and talocrural dorsiflexion(6). This allows the foot to aclapt to the ground's contour and become a mobile adapter. During running, each foot goes through these motions about 600 times per mile. When these motions are excessive, a torsional force is created which stretches the plantar fascia, resulting in inflammation and pain~ the spdrorne known as plantar fasciitis.

A Typical Case  
Plantar fasciitis is characterized by inflanimation or degeneration of the plantar fascia, particularly at the calcaneal attachment(7). It has been most1v attributed to anatomical or biomechanical abnormalities such as excessive pronation of the subtalar joint beyond the not-nial range of approximately 9.4 degrees(S). It has also been attributed to training error: reasoning that is well supported by many related studies(9),  

Other (anatomical) causes of abnormal pronation include congenital pes planus, acquired deformities, and abnormalities secondary to neuromuscular disease(10). Frequently, excessive pronation is associated with ankle joint equinus. most coinnionly caused by limited flexibility of the triceps surae, resulting in a shortened Achilles tendon(II). The cavus foot, which actually has a tight plantar fascia, conversely has a tendency toward excessive supination,  

Shoe defects are now proving to he an unexpected new cause for this common condition: one that cannot be overlooked. Relating the effects of various types of shoes to plantar fasciitis, Gross, and others(12,13), have indicated that musculoskeletal pathologies caused by external factors (e.g., an overpronator wearing a shoe designed for shock absorption rather than motion control), can also be exacerbated hy lower limb malalignments or hiomechanical imbalances. This conclusion is supported h\ clinical observations of changes in the patient's symptoms with interventions such as training modifications, corrections in running form or style, use of foot orthoses, or replacement of shoes.  

Stacoff, and colleagues(14), investigated relationships between peak impact, pronation. and forces at the subtalar joint, and on muscles (under tension during pronation) at heel strike in the rearfoot during running. Stacoff concluded that shoe design should concentrate more on controlling rearfoot movement, and less on shock attenuation.  

As the push-off phase of running is approached, the foot supinates in order to become a rigid lever and propel the body forward. So in essence, the foot initially coils to absorb the body's weight then recoils to propel the body onto the other foot(15).  

Thus, if the foot rolls in excessively, the subject is a pronator. Pronators tend to roll medially throughout the lower extremity during the stance phase. They also tend to have a more supple, shock absorbing foot. The drawback to this type of foot is that more power will be necessary during push off. When looking at old shoes of a pronator they deform medially. The medial arch of the midsole is compressed, and there is extensive wear at the lateral aspect of the heel and at the medial forefoot, The pronator may also have low arches. Therefore, while it is important for the foot to have good shock absorption, athletes with pronated feet also need shoes which emphasize control of the rearfoot.  

Research has shown that shoes constructed with soft materials in the soles and uppers, or shoes that are broken down on the medial aspect, may allow a medial roll of the foot and ankle during stance(16). Clarke, and coworkers(17), noted that shoes with a soft midsole and no heel flare allow the greatest amount of pronation, while shoes with hard midsoles and a 30 degree flare allowed the least pronation,  

Supination is on the opposite end of the spectrum from pronation. if the foot rolls out excessively, the subject is a supinator. Supinating feet do not absorb shock well, and their shoes should provide adequate cushioning for the lateral edge of the foot. Tell-tale signs of shoe wear in a supinator include old shoes that tilt laterally, laterally compressed midsoles, and soles that are overly worn along the lateral edges. Supinators usually have high arches.  

Thus, selecting a running shoe that will adequately support a runner's lower limb anatomy and biornechanics can be quite complex, as documented in several sources(18,19).

Shoe Variety  
The way people run.varies considerably, and a shoe that's right for one person can cause another blisters, musculoskeletal strains, or joint inflammation. Twenty years ago, the only criteria for buying sneakers was ensuring that the toes didn't jam against the end of the toe box. Today, however, shoe design has become sophisticated with a wide variety of choices available. it has become necessary for physical therapists, and other health care specialists, to assess foot biomechanics and running style in order to provide the patient with helpful information in choosing the correct shoe.  

Checking Feet 
It is important to determine if a patient is a pronator or a supinator, This can be done by drawing a line bisecting the Achilles tendon and the calcaneus, The alignment of these marks is evaluated with the patient standing. if the calcaneal line tilts mediallv then the foot has a tendency to pronate. Conversely. if the calcaneal line tilts laterally then the foot has a tendency to supinate(20).

Another clinical technique used to determine foot posture is to palpate the talar dome. This is done with the patient standing. if the talus is more palpable medially, then the foot is in a pronated position. if the lateral aspect of the talus is more palpable, the foot is in a supinated position.

Wear of Shoes 
A running shoe, when placed on a flat level surface, should not be biased medially or laterally. The main purpose of the shoe is to hold the foot stable. it should be constructed so its upper, midsole and outsole are firmly attached (Figure 1). The uppers, heel counter and the sole should be straight. The shoes should not rock from side to side and the shock absorbing pockets should resist collapsing under load. Defective or worn out shoes which don't hold feet in a neutral position may accentuate a preexisting musculoskeletal imbalance (i.e. excessive pronation or supination). This may lead to unnecessary aches and pains and, if not treated, a more serious or permanent injury. 

The importance of carefully inspecting running shoes for manufacturer's defects before purchase, and regular checks for uneven 

FIGURE 1. Sections and components of a running shoe.

or excessive wear throughout tile life Of tile Sll((' can not he overemphasized. The fotIm\ino guidelines will help the athlete moid bU\ III0 defective running shoes and niaN, pl-CMIt unnecessary injuries.

FIGURE 2. The upper shoe is separating from the midsole when testing is performed to pull these two parts of the shoe apart.  The outsole stays with the midsole

The shoe should be glued together seCLIICIv. Test this bv holding the shoe and trvino to pull the Lipper part of the shoe awav from the midsole, and the inidsole froin the out,,,o1c (Figure 2). Any separation will weakeii ilic shoe's support.  

The tipper part of the shoe should hc glued straight into the sole. Test this N, puttim, the shoe on a level surface and inspect the ki( k of the shoe (Figure 3A). The heel counict should appear even, and should not lean to the right (Figure 313) or left. A hrand iiex shoe th:it leans medially or laterally Could cause injuiv. especially if there is a large isyminetn' hem(Tii each shoe of a pair.  

The sole of the shoe should be level to thc surface on which the shoe is restin(. Test thr, h\ checking that the inedial and lateral aspe(t Of the heel is even when resting on a flat, level ,uiface (Figure 4A and B). Compare each shoe individually, then compare the right to the left shoe for symmetry. An asymmetry of two millimeters can tilt the shoe in or out sign ifican tl\,.  

Test for asymmetrv hv applving a (Imnward medial and a down,,vard lateral forcc to  

	FIGURE 3. A) Dotted lines show a 90° (goniometric) angle formed between the center of the heel counter and a horizontal line through the middle of the midsole of the shoe.B) Dotted lines show the right, outward lean of the upper because it is glued into the midsole at a lateral angle
FIGURE 4. A) The Medial (a) and lateral (b) vertical distances are equal on the left shoe, demonstrating that the left shoe sole is level. B)The medial (c) vertical distance is larger than the lateral (c) vertical distance on the right shoe, demonstrating that the right shoe is tilted in a lateral direction.
	FIGURE 5. A) A downward, medially directed force does nor rock the left shoe inward. B)A downward, medially directed force does rock the right shoe downward.

both the right and the left shoe to see if the shoe rocks medially and/or laterally (Figure 5A and B). Check for this asymmetry from side to side with each shoe. The shoes should remain even and not roll. if they roll when they are new, they will not stop the foot from rolling excessively when worn, and can cause injury.

Air pockets and gel pockets must be inflated evenly. Test this by pushing on the sides of the pockets medial to lateral, and lateral to medial to check for symmetry of inflation (Figure 6). Push down into the pockets both medially and laterally from the top of the pocket (Figure 7A and B). If the pockets are inflated, or filled, unevenly, this may cause the shoe to collapse irregularly, and the foot to roll when it hits the ground.

Shoe Life  
A good running shoe lasts, on average, about 300 to 500 miles. The mileage could be less if the shoes get wet in a hot, humid environment or from running in the rain. The average runner who runs 30 miles per week with normal wear and tear can expect to have a shoe life of about 10 to 15 weeks. It is a good idea to put a date somewhere on the shoes to track how long they've been in use. Shoes should also be checked periodically for signs of premature wear, since shoes that are no longer in alignment cannot keep the foot and leg in a neutral position.  

With long distance runners, mileage increases dramatically while they are training for a competitive event. However, it is not unusual for shoe models to be discontinued and a favorite shoe may suddenly become unavailable. So, it makes sense to buv an extra pair before a long training program, and put 40 to 50 dry miles on them. This will break the shoes in and this pair can then be put away in the closet until the big race.

Price May Not Ensure Quality  
The principal author. in connection with a story for a local television station, examined a variety of shoes (different brands and styles) from several sporting goods stores. The result was an alarming 30% to 50% of shoes showed defects. Surprisingly, more expensive shoes did not necessarily mean better built shoes, and these had defects, too.

Summary 
The type of running shoe worn by an athlete can be a very important factor in the prevention and treatment of lower extremity overuse running injuries. Our experience indicates the importance of checking the construction of the patient's running shoes as a possible cause of injury, particularly when other more common factors are eliminated by clinical evaluation and assessment.  

FIGURE6. A force is directed laterally with the thumb over the inside air/gel pocket to check for symmetry of inflation.
	FIGURE7. A) A downward, lateral pressure does not cause loss of height in the outside air pocket in the left shoe.  B) A downward, medial pressure causes the inside air pocket to lose height and collapse medially on the right shoe.

Additionally, when defective or excessiveh, worn shoes are found to be the cause of im, injury, it Is vital that the clinician educate the patient as to the nature of the problem. Knowing the difference between poorand good athletic shoe construction. and carefullv checking running shoes for manufacturer's defects prior to purchase will prevent unnecessary injury to the patient who runs frequently for exercise or competition.  

AMAA member, Bruce Wilk, is a board certified orthopedic p4),sical therapist and director of Orthopedic Rehabilitation Specialists. William Gutierrez is a board ceilified orthopedic phisical therapist and cert~fted athletic trainer at Orthopedic Rehabilitation Specialists. Orthopedic Rehabilitation Specialists is located at 8720 Nortb Kendall Drive, Suite 206, Miami, Florida 33176, and can be reached bv calling (305) 595-9425 or at info @defectivesboe. co m.

References 
(1) Arnheim DD: Modern principles of atletic training, St. Louis, me: Times Mirror/Mosby College Publishing, 1989.  

(2) Hall SI, Messier SP: Biomechanics of fitness exercises. In: Durstine JL (ed), King AC (ed), Painter PL (ed), Roitman JL (ed), Zwiren LD (ed), ASCA's Resource Manual for Guidelines for Exercise Testing & Prescription (2nd ed), pp 38-47. Indianapolis, IN: ACSM, Lea & Febiger, 1993.

(3) Cavanagh PR, Lafortune MA: Ground reaction forces in distance running. J Biornech 13:397406, 1980.

(4) Heil B: Lower limb biomechanics related to running injuries. Phvsiother 78(6):400-406, 1992.

(5) Pink MMJobe FW: The foot/shoe interface. In: Guten, GN (ed), Running Injuries, pp. 20-29. Philadelphia, PA: W.B. Saunders Company, 1997.

(6) Engsberg JR, Andrews JG: Kinematic analysis of the talocalcaneal/talocrural joint during running support. Med Sci Sports Exerc 19(3):275-284, 1987.

(7) Ray S: How I manage plantar fasciitis. Phys Sportsmed 11(lo):127. 131,1983

(8) Hall S1, Messier SP: Biomechanics of fitness exercises. In: Durstine .11, (ed), Kiriz AC (ed), Painter PL (ed), Roitman.IL (ed), Z%iren LD (ed), ASO ', 'esource Manual for Guidelines for Exercise Testing and Prescn,)u,,i, -i),d -d I Pp 38-47. Indianapolis, IN: ACSM, Lea & Febiger, 1993

9) Eggold JF: Orthotics in the prevention of runners' overuse njuries. Phys Sportsmed 90):125-131,198L

10) Frey C: Helping the athletic woman find a shoe that fits. J Muskuloskel Med 15(3):35-45,1998.

11) Hunt GC (ed): Physical therapy of the foot and ankle. New York, NY: Churchill Livingstone Inc., 1988.

(12) Gross MT: Lower quarter screening for skeletal malalignmentsuggestions for orthotics and shoe wear. J Orthop, Sports Phys Ther 21(6):389-405,1995

(13) James SL, Bates FIT, Csternig LR: Injuries to runners. Ain J Sports Med 6(2):40-50,1978.

(.14) Stacoff A, Denoth J, Kaelin X, Stuessi E: Running injuries and shoe construction: some possible relationships. Int J Sport Biomech 4:342-357, 1988.

(15) Novacheck TF: The biomechanics of running and sprinting. In: Guten, GN (ed), Running Injuries, pp. 4-19, Philadelphia, PA: W.B.

Saunders Company, 1997

16) Heil B: Running shoe design and selection related to ImNer limb biomechanics. Physiother 78(6):406-412, 1992,

17) Clarke TE, Frederick EC, Hamill CL: The effects of shoe deiign parameters on rearfoot control in running. Med Sci Sports Exeic

15(5):376-381,1983

(18) Martin DR: How to steer patients toward the right sport shoe. Phys Sportsined 25(9):138-144,1997,

(19) McPoil TG: Footwear. Phys Ther 68(12):1857-1965,1988.

(20) Fromherz WA: Examination. In: Hunt GC, M.A., P.T. (ed), Physical therapy of the foot and ankle, pp. 75-9. New York, NY: Churchill Livingstone, 1988.  

Bruce R. Wilk P.T.,O.C.S.
Director of Orthopedic Rehabilitation Specialists, Miami

8720 North Kendall Drive  Suite 206
Miami, Florida  33176
Phone: (305) 595-9425  Fax: (305) 595-8492
E-mail: info@defectiveshoe.com