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My conversation with Dr. Cocheba today

Posted by Ed Davis, DPM on 9/04/04 at 15:49 (159319)

I spent about 30 minutes on the phone with Dr. Cocheba who had performed and published a brilliant piece of research:

http://www.japmaonline.org/cgi/content/abstract/93/6/429

Sorry to be up on my soap box again but if I can influence just a small percent of people with PF not to get the surgery done, I have helped them tremendously. The above is just the abstract. One can order the whole paper but my conversation with Dr. Cocheba was really the 'clincher' that told me that the operation is a bad thing in that dramatic changes occur in the biomechnics of the foot when the plantar fascia is released; changes that are destructive!
Ed

Re: My conversation with Dr. Cocheba today

Pauline on 9/04/04 at 16:06 (159326)

Dr.Ed,
I think most of us that have been on this site for a long time figured this out some time ago without even reading abstracts, but its nice to see it in print.

Most of the time we are told that the cured surgical patients don't hang around or that we don't see all the good that is done.

Well I've heard from enought people on this site that have experienced failed P.F. surgeries for a life time. Personally I think this type of surgery should be look at for its failure rate and for the multitude
of complications that many, many patients experience for the rest of their lifetime.

It's not the self proclaimed 'snip and go' surgery that many doctors tell their patients and it certainly doesn't appear to be the cure all for a case of P.F. Often times it's just the opposite.

Re: My conversation with Dr. Cocheba today

Ed Davis, DPM on 9/04/04 at 16:10 (159328)

Pauline:
Your understanding is correct. It is good to have a research paper written that explains WHY the procedure is problematic. Dr. Cocheba is working on a follow up paper. Insurance companies should be taking a hard look at the surgery and considering removing it from coverage except in extreme cases.
Ed

Re: My conversation with Dr. Cocheba today

april l on 9/04/04 at 16:58 (159333)

I think there are many many more people who have had success with surgery than failure. I think that the post surgical folks who post here in near panic are those who are expecting to be pain free from the minute they leave the OR. That makes it look like a failed surgery. People like me aren't likely to post about their success stories. For one, who needs to come to a web site if there's no problem? I get the feeling that for the most part people here don't want to hear about successful EPF surgeries, especially when there are hurting people here who are suffering from the serious complications of surgery. I was scared to death of getting RSD, and I'm glad that I knew about the possibility from reading this board, my doctor never mentioned it. But, RSD is a rare complication.

Re: My conversation with Dr. Cocheba today

Ed Davis, DPM on 9/04/04 at 18:04 (159334)

April:
RSD is rare enough such that it is not mentioned routintely before PF release surgery. The success rate stands at about 60%.
Ed

Re: My conversation with Dr. Cocheba today

april l on 9/04/04 at 18:18 (159336)

The thing is my doctor says there is a 90% success rate. Why is there such a descrepancy? Who is right?

Re: Re :The full report

Julie on 9/05/04 at 02:38 (159354)

Ed, the abstract is enlightening: thanks for posting the link. I wanted to read the whole report, but was told 'This item requires a subscription to Journal of the American Podiatric Medical Association Online.' Any chance you could copy and paste it, or parts of it?

Regarding the insurance vs doctor irresponsibility issue, I don't doubt that what you say is accurate. But I also think there is an inbuilt bias towards foot surgery amongst doctors who have qualified to perform it: it's what they know how to do, so they do it (some quicker than others). It takes a long time for cultural change in a profession to take place: investment of time, energy, equipment, not to mention inertia ('we've always done it like this') are all factors. You and Dr Z, and others who can do and have done surgery for PF but have now virtually stopped, must be rare exceptions. Let's hope they get less rare as time goes on. 60% is not a success rate I would want to chance my feet on.
.

Re: Re :The full report

Ed Davis,DPM on 9/05/04 at 23:46 (159389)

Julie:

The bias exists not only among doctors but among insurance companies. You may recall a recent exchange I had with Elliott in which he insisted that insurers must critically evaluate whether to cover non-surgical modalities but basically stated that a lower level of 'proof' is needed to evaluate coverage for surgical procedures. I started a bit of a tiff when I challenged that attitiude.

Patients have often taken the attitude: 'do what is covered' and doctors often want to take the path of least resistance and that is surgery. We will need a fundamental paradigm shift in healthcare thinking among all parties to see effective change.

Even the 'mighty and powerful' are well wrapped up in the system as we see former President Clinton scheduled for triple or quadruple bypass surgery tommorrow. So called 'invasive cardiology' has, in the US, become the standard. One of our local hospital chains spent 79 million dollars this year to have the top cardiac surgical suite in town. Prevention of cardiac disease and research in non-surgical means of the treatment of coronary artery disease has been assigned to a narrow corner of the nation's budget except for the latest cholesterol lowering drug...

Coronary artery disease is unknown to many cultures and we are way overdue to understand and study the specific factors that lead to the process. Invasive cardiology is a multibillion dollar industry in the US with a relatively insignificant fraction of healthcare dollars being spent to study the causes, actual physiology of the processes involved and how those processes can be altered.

It may seem like I am getting a bit off subject here but I am doing so to emphasize the problematic thinking and priorities in US healthcare.
Ed

Re: Re :The full report

Julie on 9/06/04 at 05:39 (159398)

Ed

Not really off-topic at all. It's part of a problem that affects us all> What you describe applies to almost every disease. Look at the funds poured into mammography, which is impressively high-tech but by no means an entirely reliable diagnosic tool, compared to the funds allocated to research into the causes and prevention of breast cancer.

The issue is wider, though. Even without more research into the causes of coronary artery disease, we know enough about some of them (poor diet, smoking, lack of exercise) to be able to avoid a great deal of it. But there are big companies out there with a big investment in selling us the foods and cigarettes that erode our health in so many ways. And as for breast cancer, I suspect that environmental pollution and diet are two of the major factors in this multifactorial illness, and vested interests are ranged against us there too.

So it's not entirely a matter of how healthcare funds are prioritised.

Now that's getting even further off topic. Returning to the topic, I know about the way the insurance companies operate in the US from reading these boards over the years. I do think, regarding PF surgery, that Pauline has a good point. As doctors begin to realise, as you have, that surgery may not be the answer, and that it can cause permanent damage to foot function, they may - and I think I would agree with Pauline, should - begin to risk losing patients by simply refusing to perform it.
.

Re: Re :PS - what about the full report

Julie on 9/06/04 at 05:40 (159399)

Any chance of your copying it?
.

Re: Re :PS - what about the full report

Ed Davis,DPM on 9/06/04 at 19:34 (159441)

I will look for the full paper. It would be great if ScottR incorporated it into the site...
Ed

Re: Full report

Ed Davis,DPM on 9/06/04 at 20:00 (159448)

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PubMed Citation
Articles by Ward, E. D.
Articles by Phillips, R. D.

Journal of the American Podiatric Medical Association
Volume 93 Number 6 429-442 2003
Copyright © 2003 American Podiatric Medical Association

In Vivo Forces in the Plantar Fascia During the Stance Phase of Gait
Sequential Release of the Plantar Fascia
Erin D. Ward, DPM *, Kevin M. Smith, DPM , Jay R. Cocheba, DPM , Patrick E. Patterson, PhD and Robert D. Phillips, DPM (PIPE)(PIPE)
* Central Iowa Foot Clinic, PC, Perry.
Department of Podiatric Medicine, College of Podiatric Medicine, Des Moines University, Des Moines, IA.
Broadlawns Medical Center, Des Moines, IA.
Department of Industrial and Biomedical Engineering, Black Engineering, Iowa State University, Ames.
(PIPE)(PIPE) Podiatry Section, Veterans Affairs Medical Center, Coatesville, PA.

Corresponding author: Erin D. Ward, DPM, Central Iowa Foot Clinic, PC, 1302 Warford St, Perry, IA 50220.

Abstract

Plantar fasciotomies have become commonplace in podiatric and orthopedic medicine for the treatment of plantar fasciitis. However, several complications have been associated with plantar fascial release. It has been speculated that the cause of these complications is excessive release of the plantar fascia. The aim of this project was to determine whether the amount of fascia released, from medial to lateral, causes a significant increase in force in the remaining fascia. A dynamic loading system was developed that allowed a cadaveric specimen to replicate the stance phase of gait. The system was capable of applying appropriate muscle forces to the extrinsic tendons on the foot and replicating the in vivo timing of the muscle activity while applying force to the tibia and fibula from heel strike to toe-off. As the plantar fascia was sequentially released from medial to lateral, from intact to 33% released to 66% released, the real-time force and the duration of force in the remaining fascia increased significantly, and the force was shifted later in propulsion. In addition, the subtalar joint was unable to resupinate as the amount of fascia release increased, indicating a direct relationship between the medial band of the plantar fascia and resupination of the subtalar joint during late midstance and propulsion. (J Am Podiatr Med Assoc 93(6): 429-442, 2003)

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Background
Anatomy

The plantar surface of the calcaneus is triangular, with its most posterior aspect containing two ridges beside a depression. These two ridges have become known as the medial and lateral tubercles. The lateral tubercle is smaller than the medial tubercle, and it allows for partial attachment of the abductor digiti minimi and the long plantar ligament. The larger and broader medial calcaneal tubercle allows for attachment of the abductor hallucis, the flexor digitorum brevis, the medial head of the quadratus plantae, and the abductor digiti minimi muscles, along with the long plantar ligament. Cancellous bone sectioning and neutron diffraction studies indicate that the calcaneus contains both compression and tension lamellae.1 Compression lamellae surround the articular surfaces and the posterior plantar aspect of the calcaneus. Tension lamellae are observed at the attachment of the Achilles tendon and the plantar fascia, indicating that the plantar fascia produces a significant amount of tension on the plantar calcaneus.2, 3

The plantar fascia is composed of three strong bands (medial, central, and lateral) formed by collagen fiber matrices.4 The medial calcaneal tubercle functions as a partial attachment site for the medial and lateral bands and as a total attachment site for the central band. Barrett et al5 found the mean width of the medial band to be 13.48 mm, the central band to be 4.54 mm, and the lateral band to be 10.77 mm, for a total mean width of 28.78 mm. They found the mean thickness of the medial band to be 4.45 mm, the central band to be 1.57 mm, and the lateral band to be 2.54 mm. Hawkins et al6 conducted a cadaveric study of plantar fascial release in which the average width and thickness of the fascia were 17.4 mm and 3.5 mm, respectively; the average percentage of fascia cut was 82%. These three bands divide into five bands as they proceed distally. At the metatarsal heads, the five bands attach to the metatarsals via the superficial transverse metatarsal ligament. Smaller slips of plantar fascia cross the metatarsophalangeal joints and attach to the proximal phalanges, allowing the 'windlass effect' described by Hicks7 to occur when the metatarsophalangeal joints are extended.

Plantar Fascia Biomechanics

Plantar fascial function and its relationship to the function of the foot has been a point of investigation for many years. In 1943, Lapidus8 concluded that the foot could not be considered an arch, or at least not an arch in architectural terms, because the bones of the foot cannot stand alone without soft-tissue structures. He believed the foot to be a truss, with the bones of the foot being in compression and the plantar fascia being in tension. Twenty years later, in 1963, Lapidus9 published a second article concerning whether the foot is an arch or a truss. He again concluded that the foot should be considered a truss, with the bones of the foot being in compression and, this time, not only the plantar fascia but also the plantar ligaments being in tension.

Hicks7 was the first to publish data on the mechanics of the plantar fascia. He noted that upon extension of the metatarsophalangeal joints, the height of the longitudinal arch of the foot increased. He went on to hypothesize that the plantar fascia must increase in tension for the windlass effect to occur during propulsion. Hicks10 proposed a formula by which the tension in the plantar fascia can be determined. Wright and Rennels11 revised Hicks' equation and applied it to lateral foot radiographs. With their equation, Wright and Rennels indicated that the tension on the fascia should be approximately 47% of the tibial load. However, neither equation accounts for the three-dimensionality of the plantar fascia or for the three separate fascial bands. MacConaill12 and Sarrafian,13 on the other hand, view the foot as a twisted plate. As a twisted plate, the plantar fascia is tensed when the talotibial complex is internally rotated, the rearfoot and midfoot are pronated, and the forefoot is supinated.

The integrity of the plantar fascia has become synonymous with proper foot function. Therefore, the material properties of the plantar fascia are important in determining the role that the plantar fascia plays in the integrity of the foot during stance as well as propulsion. Wright and Rennels11 noted that the modulus of elasticity of the plantar fascia increased as the load on the fascia increased, reaching a maximum of 0.12 x 106 pounds per square inch. A load of 2,500 pounds was placed on the plantar fascia, at which time the plantar fascia underwent elastic deformation, followed by elastic recovery when unloaded. Wright and Rennels surmised that at 200 pounds of tibial load, the plantar fascia underwent elongation of only 1.68%. A more recent study conducted by Kitaoka et al14 determined that the mean ± SD force at which the plantar fascia ruptured was 1,540 ± 246 N in men and 1,002 ± 101 N in women.

Ker et al15 and McMahon16 established that upon flattening of the arch, the foot stored the energy produced by the compression and then released the stored energy in the form of elastic recoil. Ker et al believed the energy to be stored in both the plantar fascia and the plantar ligaments. Simkin and Leichter17 constructed a formula that they believed correlated the calcaneal inclination angle with the amount of energy created when the medial longitudinal arch flattened. Kitaoka et al14 determined the failure rate of the plantar fascia to be 111.2 N/sec. At 11.1 N/sec, they found the mean ± SD stiffness of the plantar fascia to be 203.7 ± 50.5 N/mm and the average force at which failure occurred to be 1,189 N. Kim and Voloshin18 created a mathematical model of the foot for determining the role of the plantar fascia in the integrity of the foot. Their data indicated that the fascia carried approximately 14% of the total load applied to the foot. They also found that the fascia was important for shock absorption. A biomechanical model created by Arangio et al19 demonstrated a significant increase in vertical displacement and horizontal length of the model with the plantar fascia released.

Cadaveric Plantar Fascia Research

With the increasing acceptance that the inferior calcaneal exostosis is not involved in plantar fasciitis, plantar fascial release alone has become the primary target of surgical relief of plantar fasciitis. This concept was first introduced by Spitzy20 in 1937. However, several studies indicate that the plantar fascia is an integral component of foot function, especially the stability of the longitudinal arch and midtarsal joint. Huang et al21 examined longitudinal arch stability through serial sectioning of the plantar fascia and the long plantar, short plantar, and spring ligaments. This study indicated that the plantar fascia was the structure most important to the integrity of the medial longitudinal arch. Kitaoka et al22 noted that with the application of increasing loads to the tibia, the height of the medial longitudinal arch decreased.

Thordarson et al23 evaluated the role of the plantar fascia in foot function through serial sectioning of one-quarter, one-half, three-quarters, and full release of the fascia. They noted a decrease in arch height and an increase in foot length once half of the fascia was sectioned. A cadaveric study conducted by Kitaoka et al24 in 1997 demonstrated a significant decrease in sagittal plane height of the talotibial joint, the talometatarsal joint, and the talocalcaneal joint upon complete plantar fascial release. In a study conducted by Murphy et al,25 an equinus rotation of the calcaneus and a drop in the cuboid occurred when the entire plantar fascia was cut, but this was not observed when only one-third of the fascia was transected.

Thordarson et al26 found the plantar fascia to be significantly involved in the development of flatfoot deformity. Cadaveric studies undertaken by Sharkey et al27, 28 indicate that plantar fascial release disrupts the configuration of the medial longitudinal arch and significantly decreases the transfer of load to the forefoot during propulsion. Carlson et al29 found a direct relationship among the increasing force in the Achilles tendon, the increasing dorsiflexion of the metatarsophalangeal joint, and the increasing tension in the plantar fascia. A study conducted by Anderson et al30 indicated that as the plantar fascia is sequentially released, the inferior sinus tarsi joint space increases, the lateral band of the plantar fascia length increases, and the medial longitudinal arch height decreases. Hamel et al31 discovered that when the plantar fascia was totally released, the contact pressure under the digits decreased, the pressure under the metatarsal heads increased, and the forefoot pressure underwent a posterolateral shift during simulated propulsion.

In Vivo Plantar Fascia Research

Several postoperative studies have been undertaken to assess complications following plantar fasciotomy. Daly et al32 investigated the biomechanical significance of dividing the central band of the plantar fascia. They found a significant decrease in arch height postoperatively. The study also indicated that fasciotomy patients proceeded through the stance phase more rapidly and applied much less vertical force than controls, and thus had a less efficient gait. Gormley and Kuwada33 noted that of nine patients in whom 0.5 cm of plantar fascia was resected, all experienced complete relief of their symptoms. Barrett and Day,34 in an initial study of endoscopic plantar fascial releases, noted the occurrence rate of midtarsal pain postoperatively to be 9.6%. White35 noted that upon release of the plantar fascia and plantar musculature at the area of the medial calcaneal exostosis in 30 feet, 27 feet exhibited metatarsalgia or lateral column pain at a minimum of 4 weeks. A more recent analysis of endoscopic plantar fascial release by Barrett et al36 indicated that lateral column pathology, similar in clinical presentation to cuboid syndrome, occurred at a rate of at least 4.25%. In a follow-up study of 652 plantar fasciotomies, Barrett et al37 found 62 complications postoperatively. Of the 62 complications, 25 were associated with the calcaneocuboid joint. They believed this to be due to disproportionate excision of the medial and central bands of the plantar fascia, causing an increase in tension in the lateral fascial band and a change in force at the calcaneocuboid joint. In a follow-up study of endoscopic plantar fasciotomies, Stone and Davies38 found a significant decrease in calcaneocuboid pain when a cast was applied postoperatively.

Materials and Methods

A specially designed dynamic gait–replicating loading system known as the Dynamic Gait Replicator was developed for this study. The Dynamic Gait Replicator is composed of a platform on a rail, with a variable motor and cable attached to the platform capable of pulling the platform linearly (Fig. 1). Nine motors with controllers and gear reducers are attached to the platform, with an encased cable attached to each gear reducer. Each of these cables extends from the platform and is attached to a strain gauge. A pneumatic cylinder capable of applying 1,112.5 N of force is also attached to the platform. A manufactured functional knee joint is attached to the cylinder ram. Four fresh-frozen specimens that were severed 11 cm proximal to the tibial plafond were obtained for this study. Skin and subcutaneous tissue were removed to 5 cm proximal to the tibial plafond to show the individual extrinsic muscles of the foot and yet leave the retinacula intact. Two Kirschner wires with markers were driven into the posterior tibia, and two were driven into the posterior calcaneus of each specimen for obtaining kinematic data (Fig. 2). Each extrinsic tendon was transected at its musculotendinous junction. A braided line capable of withstanding 667.5 N of force was knotted to each tendon. A steel rod was driven into the intermedullary canal of the tibia of each specimen, with a second rod fixed to the fibula, and both were attached to the distal portion of the manufactured knee joint. Each braided line from the individual extrinsic tendons was then attached to the opposite end of the strain gauge from the encased cable (Fig. 3).

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Figure 1. Top view of platform. 1, Pneumatic cylinder; 2, motor controller; 3, motor; 4, gear reducer.





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Figure 2. Rearfoot, with arrows indicating markers on the posterior leg and calcaneus.





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Figure 3. Medial aspect of specimen. 1, Tibial rod; 2, cable from motor; 3, strain gauge; 4, braided line.




A controller board (Fig. 4), created from electromyographic data, was placed below the platform so that as the platform moved over the controller board, each motor (ie, muscle) was triggered to activate and release as in vivo. The force applied by each motor from heel strike to toe-off was derived from feedback through each strain gauge using LabVIEW software (National Instruments Corp, Austin, Texas), and the force was adjusted using the motor controller to replicate theoretical in vivo muscle forces as indicated by Dul et al,39 Brand et al,40 and Perry41 (Fig. 5). A 2-cm incision was made on the medial aspect of the foot to visualize and measure the medial band of the plantar fascia, and a 2-cm incision was made on the lateral aspect of the foot to visualize and measure the lateral band of the plantar fascia. A microstrain gauge (MicroStrain, Inc, Williston, Vermont) was implanted in the medial band of the plantar fascia, and a microstrain gauge was implanted in the lateral band of the plantar fascia (Fig. 6). The real-time forces being applied to each microstrain gauge were read using LabVIEW throughout the stance phase of gait.

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Figure 4. Muscle activity controller board.





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Figure 5. LabVIEW screen, with each curve demonstrating muscle activity for each extrinsic tendon.





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Figure 6. Microstrain gauge.




Each foot was then walked from heel strike to toe-off for three trials with the plantar fascia intact (Fig. 7). The muscle forces and timing as well as the forces in the plantar fascia were collected from LabVIEW for each trial. The plantar fascia was then released sequentially, from medial to lateral, 33%, then 66%, and finally 100%, with data collected at each stage. The maximal force and the impulse (area under the force–time curve) within the medial and lateral bands of the plantar fascia were ascertained using ImageJ (National Institutes of Health, Bethesda, Maryland). A digital camera was placed behind the specimen, and each trial was video taped to capture movements of markers for frontal plane subtalar motion. Each video was segmented frame by frame and each marker was hand-digitized using VirtualDub (National Institutes of Health). Angular changes between the markers were measured using Scion (National Institutes of Health) at heel strike, forefoot loading, and heel-off and just before toe-off.

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Figure 7. Specimen walking in real time from heel strike to just before toe-off. The images should be viewed from top to bottom, column by column.




Results
Validation of Dynamic System

To validate the plantar fascia force data, we determined that the cadaveric specimen had to replicate the in vivo foot mechanically during the stance phase of gait in real time. Two systems were used: first was plantar force data from heel strike to just before toe-off using the F-Scan force-measuring system (Tekscan, Boston, Massachusetts) (Fig. 8) and the second was rearfoot kinematics throughout stance (Fig. 9). Data from kinematics as well as plantar pressures were found to be essentially identical to in vivo data, indicating that the Dynamic Gait Replicator did indeed produce cadaveric dynamic gait similar to in vivo gait.

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Figure 8. F-Scan data from heel strike to just before toe-off with the plantar fascia intact.





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Figure 9. Frontal plane subtalar joint motion with the plantar fascia intact from heel strike to just before toe-off. HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.




Plantar Fascia Force Data with Sequential Release of the Plantar Fascia
This study demonstrated that real-time forces in the cadaveric plantar fascia could be obtained in a dynamic cadaveric scenario (Table 1). With the entire fascia intact, the force in the medial band began just after heel strike and had two peaks: a lower first peak during midstance and a second larger peak during early propulsion. Force in the lateral band of the plantar fascia also began just after heel strike and peaked at early midstance and then peaked a second time during early propulsion. Unlike in the medial band, the second lateral band peak is smaller than the first (Fig. 10).

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Table 1. Impulse in the Lateral Band of the Plantar Fascia in a Dynamic Cadaveric Scenario





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Figure 10. A, Impulse in the medial and lateral bands of the plantar fascia with the entire fascia intact; B, impulse in the lateral band of the plantar fascia with 33% of the plantar fascia released; C, impulse in the lateral band of the plantar fascia with 66% of the plantar fascia released.




The impulse in the lateral band of the plantar fascia increased significantly throughout stance in all specimens tested from intact to 33% of the plantar fascia released. When 66% of the fascia was released, the impulse in the lateral band also increased significantly from that observed with 33% released in all but one specimen (Fig. 11). This increased force also occurred earlier in stance and peaked during propulsion (Fig. 12).

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Figure 11. Impulse in the lateral band of the plantar fascia of all four specimens during the stance phase of gait with the plantar fascia intact, 33% released, and 66% released.





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Figure 12. Impulse in the lateral band of the plantar fascia throughout the stance phase of gait during plantar fascial release in Specimen 10602 (A), Specimen 11202 (B), Specimen 12002 (C), and Specimen 12702 (D). HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.




Rearfoot Kinematic Data with Sequential Release of the Plantar Fascia
With the plantar fascia intact, the subtalar joint was noted to be supinated prior to heel strike and to progressively pronate until midstance, at which time the subtalar joint began to resupinate. Supination continued until heel-off, at which time the subtalar joint returned to neutral and continued to supinate. When 33% of the plantar fascia was released, there was not a significant increase in subtalar joint pronation during contact and early midstance. During the latter half of midstance, the subtalar joint began to resupinate, but it was unable to continue resupinating after heel-off. When 66% of the plantar fascia was released, the subtalar joint pronated normally in contact; however, it remained pronated and was unable to resupinate to neutral before heel-off. When the plantar fascia was completely released, the results were similar to when 66% of the fascia was released: the subtalar joint remained pronated from just after heel strike throughout the remainder of stance and was unable to resupinate before heel-off. Interestingly, in two specimens, the subtalar joint resupinated more when the plantar fascia was completely released than when only 66% of the fascia was released (Fig. 13). Also, a direct relationship was found between the increasing force in the lateral band of the plantar fascia from intact to 33% and 66% released and increased subtalar pronation (Figs. 14 –17).

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Figure 13. Frontal plane subtalar joint motion with the plantar fascia intact, 33% released, 66% released, and 100% released in Specimen 10602 (A), Specimen 11202 (B), Specimen 12002 (C), and Specimen 12702 (D). HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.





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Figure 14. Impulse in the lateral band of the plantar fascia compared with frontal plane subtalar joint motion with the plantar fascia intact (A), 33% released (B), and 66% released (C) in Specimen 10602. HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.





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Figure 15. Impulse in the lateral band of the plantar fascia compared with frontal plane subtalar joint motion with the plantar fascia intact (A), 33% released (B), and 66% released (C) in Specimen 11202. HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.





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Figure 16. Impulse in the lateral band of the plantar fascia compared with frontal plane subtalar joint motion with the plantar fascia intact (A), 33% released (B), and 66% released (C) in Specimen 12002. HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.





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Figure 17. Impulse in the lateral band of the plantar fascia compared with frontal plane subtalar joint motion with the plantar fascia intact (A), 33% released (B), and 66% released (C) in Specimen 12702. HS, Heel strike; FFL, forefoot loading; HO, heel-off; Pre-TO, before toe-off.




Discussion
The etiology of plantar fasciitis and the etiology of complications associated with partial and complete release of the plantar fascia have spawned many investigations. Although they added some insight into the potential causes of these phenomena, the previous studies have been constrained either by mathematical modeling or by static or quasi-dynamic cadaveric modeling.

We believe that the system we developed overcomes most of these constraints by providing a model capable of replicating gait. The model was validated through the use of kinematics and ground reaction force data. Heel strike to just before toe-off occurred in approximately 0.6 to 0.8 sec for each specimen, with muscle force curves read by LabVIEW in close agreement with attenuation and length of activity with electromyographic data presented by Perry.41 We realize that the model did not apply force to any of the intrinsic musculature of the foot that may also play a role in stabilizing the foot during gait. We believe that the strain gauges implanted in the plantar fascia provided the closest determination of real-time forces in the medial and lateral bands throughout the stance phase of gait.

As the plantar fascia was transected from medial to lateral at 33% and 66%, the impulse significantly increased in the lateral band of the fascia. The observed loss of resupination of the subtalar joint when the medial band of the plantar fascia was released seems to be a significant finding, as no other changes were made in the foot structure or function except release of the medial band of the plantar fascia. It seems that the extrinsic supinatory muscles were adequate to provide enough force to keep the initial subtalar joint velocity under control and prevent the subtalar joint from pronating excessively during the contact period. However, it seems that tension in the medial band of the plantar fascia provided the necessary force on the subtalar joint during late midstance and propulsion to create resupination of the subtalar joint. This may explain the postoperative foot instability observed in 4.25% to 9.6% of plantar fasciotomy patients and may be one of the etiologic factors involved in plantar fasciitis. Therefore, any device that would assist in resupinating the subtalar joint from its normal pronation during contact would alleviate the pain associated with plantar fasciitis. We realize that it can be argued that as the released plantar fascia in vivo heals, the fascia may become reattached to the calcaneus through fibrous tissue. However, whether the healed plantar fascia will be able to produce resupination of the subtalar joint has not been studied.

Conclusion

Although plantar fasciotomies continue to be used to relieve the heel pain associated with plantar fasciitis, there are no criteria as to the amount of fascia release required to relieve symptoms while maintaining the integrity of foot function. This study demonstrated that it is conceivable for a device to be fabricated to allow the cadaveric foot to replicate the in vivo foot during the stance phase of gait. The study demonstrated that partially releasing the plantar fascia imparts forces to the remaining fascia that are not usually observed with the fascia intact. Not only did the impulse increase, but a shift was noted in where the maximal force occurred during gait. When the plantar fascia was released, the subtalar joint was unable to resupinate in late midstance and propulsion, and there seems to be a direct correlation between the amount of fascia transected and the subtalar joint's inability to resupinate. Although the exact nature of this relationship was not ascertained from the study, resection of the medial band of the plantar fascia was the only variable changed with the lack of resupination. More research is needed to determine more precisely the amount of plantar fascia that can be released before significant increases in forces in the remaining fascia are observed and before loss of the subtalar joint's ability to resupinate during late stance and propulsion. From this initial study, it seems that less than 66% of the fascia should be released to maintain foot stability, which is in agreement with in vivo research on lateral column symptoms following plantar fascial release.42






Acknowledgments

The Iowa Osteopathic Education Foundation and the Central Iowa Foot Clinic, PC, for funding this project; the University of California, San Diego, for specimens; the IE 386 class at Iowa State University and Greg Leuke, PhD, of Iowa State University for aiding in development of the loading system; MicroStrain, Inc, for supplying the microstrain gauges and the amplifier for determining the forces in the plantar fascia; and Kevin A. Kirby, DPM, and Christopher J. Nester, PhD, for technical assistance with validating the loading system.

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Re: Full report

scott r on 9/06/04 at 21:36 (159462)

i'm including most of the conclusion in the online book and surgery page as follows:

Although plantar fasciotomies continue to be used to relieve the heel pain associated with plantar fasciitis, there are no criteria as to the amount of fascia release required to relieve symptoms while maintaining the integrity of foot function. .... The study demonstrated that partially releasing the plantar fascia imparts forces to the remaining fascia that are not usually observed with the fascia intact. .... When the plantar fascia was released, the subtalar joint was unable to resupinate in late midstance and propulsion, and there seems to be a direct correlation between the amount of fascia transected and the subtalar joint's inability to resupinate. .... More research is needed to determine more precisely the amount of plantar fascia that can be released before significant increases in forces in the remaining fascia are observed and before loss of the subtalar joint's ability to resupinate during late stance and propulsion. From this initial study, it seems that less than 66% of the fascia should be released to maintain foot stability, which is in agreement with in vivo research on lateral column symptoms following plantar fascial release.


Re: Re :PS - what about the full report

Julie on 9/07/04 at 01:54 (159474)

Thanks very much for doing this, Ed. I'll read it with interest.
.

Re: Full report

BrianG on 9/07/04 at 19:29 (159522)

Looks like I picked a good day to check back in. Most of you probably know that I had a failed EPF, on my right heel, Sept, 1999. The operation was a failure, but I'm happy that I developed no complications (that I'm aware of). Most of this report was over my head, but I did notice that boot casts are now being used after the surgery. I'm glad to hear that, as I was told to get back into my Asics, and start walking from about the thrd day on (when tyhe stitches came out). After the first couple weeks I was in agony, the amount of time I was supposed to walk, went up considerably. I reported this to my Pod, but he just said to walk as much as I could stand!!! No mention of a cast, or PT for that matter. My heel was very painful for a good month, and it was 3 months, before I was able to return to work.

Just a couple days ago, I decided to check Dr Barrett's web site. He is the person who developed the 2 portal method that was used back then. He was the main man. Now he doesn't even have a web site, hmmmmmm. I wonder what thats all about? Oven getting a little too hot, time to get out??????

I did log in to ask a question, if anyone wants to have a look, it'll be under the 1st section, products.

Regards,
BrianG

Re: Full report

Dr. Z on 9/07/04 at 20:17 (159526)

Hi Brian G

They still teach this procedure at almost every convention around the USA

Re: Full report

Ed Davis, DPM on 9/07/04 at 23:53 (159537)

It is a very simple procedure and lucrative and has the blessings of the insurance industry. One must give into temptation on this one...
Ed