Biomechanical and histiological considerations for development of
plantar fasciitis and evaluation of arch taping as a treatment option to
control associated plantar heel pain: a single-subject design
Gary C. Hunt
a,b,c,∗, Tom Sneed
b, Herb Hamann
b,c, Sheldon Chisam
caPhysical Therapy Program, Franklin Pierce College, 5 Chenell Drive, Concord, NH 03301, USA bDepartment of Physical Therapy, Southwest Baptist University, 1600 University Avenue, Bolivar, MO 65613, USA
cCox Health Care Systems, Springfield, MO, USA
Received 6 January 2004; received in revised form 28 March 2004; accepted 30 March 2004
Abstract
Study design: Alternating single-subject A-B and A-B-A designs. Objective: To discuss biomechanical and histiological issues related to
the development of plantar fasciitis and to evaluate the effectiveness of arch taping in controlling heel pain during ambulation. Background: Plantar heel pain as a consequence of plantar fascial strain, a condition frequently diagnosed as plantar fasciitis, can significantly interfere with functional ambulation. Biomechanical causes of plantar fasciitis have been related to microfailure of plantar fascial tissue followed by incomplete repair resulting from abnormal histiological responses. Arch taping has been suggested as a viable treatment option for patients with this diagnosis but few studies have documented its clinical effectiveness in reducing pain. Methods and measures: Two female subjects diagnosed with plantar fasciitis with a history of chronic heel pain participated in the clinical evaluation. Time to onset of pain was recorded during ambulation with and without arch taping on several days. Results: Visual and statistical analysis using the Two Standard Deviation Band method showed improvement at theP <0.05 significance level in walking time for both subjects with arch taping. Conclusions: Biomechanical and histiological factors need to be considered for successful management of plantar fasciitis. The arch taping technique applied in these two cases was effective in controlling pain during ambulation and could be considered as a viable treatment option for other individuals with similar clinical presentations. Slower healing time of dense connective tissue such as plantar fascia needs to be protected for longer periods of time to ensure resolution of plantar fasciitis.
© 2004 Elsevier Ltd. All rights reserved.
Keywords: Plantar fasciitis; Heel pain; Plantar foot pain; Arch taping
1. Introduction
Heel pain involving the plantar fascia, frequently diag-nosed as plantar fasciitis, has been identified as one of the most common foot complaints in adults[1–5]. The typical chief complaint shared by most individuals with this condi-tion is pain under the medial heel during weight bearing, es-pecially with the first few steps in the morning. The patient might also note similar pain with initial steps after prolonged sitting or inactivity during the day[2–8]. Typically this pain is reported to ease after walking a short distance only to worsen over the course of the day with further weight bearing activities[2,5]. There is often no specific incident associated
∗Corresponding author. Present address: 79 Sailboat Lane, Kimberling
City, MO 65686, USA. Tel.:+1-417-739-5495. E-mail address: [email protected] (G.C. Hunt).
with the onset of pain but weight bearing activities seem to be consistently associated with this pain pattern[7,8].
Conservative mechanical treatment of this condition has included a variety of orthotic and taping approaches[9–16]. The purpose of this paper is to address biomechanical and histiological considerations in the development of plantar fasciitis and to evaluate the effectiveness of arch taping in controlling pain during ambulation through two case studies.
1.1. Biomechanical and histiological considerations Treatment of chronic plantar fasciitis can often be frus-trating for the patient and clinician alike due to the slow healing process of dense connective tissue. Constant remod-eling of dense connective tissue occurs at a slower rate than other more metabolically active tissues such as skin, muscle, and bone [17–20]. Although therapeutic tensile force has 0958-2592/$ – see front matter © 2004 Elsevier Ltd. All rights reserved.
been identified as an important element to promote strong healthy ligaments and tendons, when the magnitude of these forces becomes too large or are applied too frequently, the mechanical integrity of these dense connective tissues may be compromised [17,21]. One important goal for optimal treatment should relate to biomechanical control of tensile force transmitted through the plantar fascia.
An understanding of the biomechanical forces contribut-ing to the development of tension in the plantar fascia is important in order to arrive at better management options. The biomechanical functions of the plantar fascia involve support of the longitudinal arch of the foot and shock ab-sorption during stance[22–24]. The breaking strength of the plantar fascia has been estimated to be 1.7–3.4 times body weight[25]. Gefen [26]estimated that the tensile stress in the plantar fascia peaked around 800–1000 N during termi-nal stance of walking. The biomechanical events responsi-ble for producing this tensile force relate to: (1) subtalar and midtarsal joint pronation during the first part of stance
[4,27]; (2) soleus and gastrocnemius muscle contraction dur-ing terminal stance[28]; and (3) the windlass mechanism occurring during terminal stance when the heel is off the ground[22,24].
During the first part of stance, the arch normally lowers as a result of coupled motion of leg internal rotation and subtalar and midtarsal joint pronation. If this motion occurs too rapidly, or is excessive in magnitude or frequency, the plantar fascial tissues may experience microfailure[4,9,27]. The second mechanism occurs as forward progression pro-ceeds over the forefoot. The soleus and gastrocnemius con-tract near maximum capacity in order to lift the heel off the ground and promote forward progression[28]. This forceful contraction produces a torque on the calcaneus that tends to pull the calcaneus posterior and superior. A main restrain-ing tissue to counteract this torque is the plantar fascia. This event during terminal stance places additional tensile stress through the plantar fascia.
A third mechanism is the windlass effect acting through the metatarsophalangeal joints with particular contribution from the first metatarsophalangeal joint[22,24,29]. During terminal stance, as the soleus and gastrocnemius muscles contract vigorously to lift the heel off of the ground, ex-tension occurs at the metatarsophalangeal joints. The plan-tar fascial bands wrap around the convex surface of the metatarsal heads producing a windlass effect. This wind-lass mechanism increases the tension in the plantar fascia, raises the longitudinal arch, and tends to resist the posterior and superior rotation of the calcaneus. It appears that the contracting posterior calf muscles and the opposing forces generated by the windlass mechanism have the potential of producing the greatest amount of tensile force in the plantar fascia. Treatment approaches, therefore, need to be consid-ered for this terminal part of the gait cycle as well as during the first part of stance.
Heel pain from plantar fasciitis appears related to chronic damage from microfailure of the tissues followed by
incom-plete repair. Some studies have discussed a variety of adverse cellular and tissue changes such as myxoid degeneration and fibroblast necrosis, chondroid metaplasia, angiofibrob-lastic proliferation, collagen degeneration with loss of fiber continuity, abnormally increased ratio of Type III to Type I collagen, increased numbers of abnormal fibroblasts with mitochondrial defects, and abnormal new vascular vessels without blood cells that have no connections to other nor-mal vessels[30,31]. Of interest is that chronic long-standing cases of plantar fascial strain have minimal if any evidence of inflammatory cells present within the involved tissue[31]. 1.2. Arch taping
Taping is one method that has been utilized to biomechan-ically control tensile forces generated through the plantar fascia[15,32–36]. Much of the research on taping has mea-sured various biomechanical parameters including rearfoot motion[32], navicular drop[34–36], and coupled transverse tibial rotation with subtalar pronation[33]on normal sub-jects. However, only Saxelby et al.[15]attempted to mea-sure the effectiveness of arch taping in reducing heel pain in subjects with plantar fasciitis. In addition to Saxelby et al., others[32,33]have recommended further clinical studies us-ing arch tapus-ing on patients with plantar fasciitis. Therefore, the second intent of this paper is to further evaluate the effec-tiveness of an arch taping technique to control pain during ambulation in two female subjects with a medical diagnosis of plantar fasciitis.
2. Methods 2.1. Subjects
Case one was a 60-year-old female with an 8-year history of left plantar heel pain. She could not relate any specific history of trauma except she thought that she stepped on a nail sometime in her past which may have had some influ-ence in the development of her heel pain. She described point tenderness beneath the medial plantar calcaneus, which was most uncomfortable with the first few steps in the morning. She had a number of steroid injections over the 8-year period and had taken a variety of anti-inflammatory medications without any lasting improvement. She described her most intense pain to be present from just after left heel-contact through left heel-off during gait. She was referred to physi-cal therapy for stretching exercise and heat and cold modal-ities for pain control. She was seen for a total of six visits where arch taping was the main treatment intervention over a two-week period of time.
Case two was a 38-year-old female with a 2-year history of left plantar heel pain. She had noticed increased pain 3 months prior to referral to physical therapy during which time she had two steroid injections with only 1–2 days re-lief of symptoms after each injection. She had been using
an over-the-counter foot orthotic device with only marginal relief. Her morning pain was listed as a 7/10 on a pain scale of 1–10, with 0 no pain and 10 maximum pain. The use of oral anti-inflammatory medications did not provide any noticeable relief of pain. She experienced most of her pain during the latter part of left single limb stance. Ankle joint dorsiflexion was 5◦ on the left and 10◦ on the right and muscle strength was within normal limits bilaterally. The remainder of the examination was normal. The emphasis in her treatment program was arch taping. In addition she was instructed on range of motion exercises and massage to the foot and ankle that she would perform at home. She was seen for a total of five treatments over a 3-week period of time. 2.2. Research design
A single-subject alternating treatment design[37,38]was used to evaluate the effectiveness of arch taping in
reduc-Fig. 1. Place involved foot on opposite knee. Hold ankle in about 90◦. Fig. 2. (a and b) Apply tape strip that will cover metatarsal heads. Fig. 3. (a and b) Apply long tape-strip to wrap around back of calcaneus and onto lateral plantar foot from approximately the 5th to 3rd metatarsal heads. Fig. 4. (a and b) Attach the medial portion of the long tape-strip to approximately the 1st to 3rd metatarsal heads. Fig. 5. Apply short tape strip that will cover the metatarsal heads to anchor the long strip. Fig. 6. Continue to apply short strips proximally to cover the entire plantar foot. Fig. 7. (a and b) Completed arch taping procedure viewed from medial and plantar surfaces.
ing pain during ambulation. An A-B design was used for case one and an A-B-A design was used for case two. “A” condition was “no tape” and “B” condition was “tape”. The outcome measure was time to onset of pain during ambu-lation. In case one the individual ambulated on a treadmill at a velocity of 53.7 m/min while case two ambulated on an indoor walking track at her preferred walking velocity. The mode and intensity of ambulation was selected for comfort and convenience of each patient.
2.3. Taping technique
The original low-Dye taping technique and another popu-lar arch taping technique, called the “double-X”, have been utilized to support the medial longitudinal arch of the foot
[32,39–42]. Both of these techniques have reportedly tried to control excessive subtalar joint pronation, which is of-ten associated with injuries of the foot[9,32,33]. The taping
procedure used for the two cases in this study was a modi-fication of the “double-X” arch taping technique described by Ator et al.[42].
Multi-purpose polyethylene coated cloth tape (47 mm, Tyco, Norwood, MA) with natural rubber based adhesive was applied with the patient seated and the involved ankle resting on the uninvolved knee. The ankle was maintained in 0◦of dorsiflexion during tape application. The difference in this taping procedure from that described by Ator et al.
[42]was primarily that the tape-strip wrapping around the posterior calcaneus followed more closely the direction of the medial band of the plantar fascia to the first metatarsal head instead of crossing the plantar foot to anchor at the fifth metatarsal head.Figs. 1–7b demonstrate the application of the taping procedure.
3. Procedure
Both subjects wore low-quarter shoes during all testing trials. The sequence of testing differed between the two cases as a matter of convenience and clinical preference. The out-come measure for both cases was the time to onset of pain during ambulation. This outcome measure was selected in order to minimize the escalation of pain for each subject and to avoid influence of pain between testing conditions. Case one was tested using an A-B design. She was tested on 6 separate days over a 2-week period. On each day she was in-structed to ambulate on a treadmill at 53.7 m/min at 0% grade without tape to the point when she first noticed the onset of pain or when she reached a predetermined ending-time of 8 min. She stopped walking and the time was recorded. Her arch was then taped and she walked again on the treadmill as previously described. She ended the evaluation period with six trials walking without tape and six trials with tape. Case two was tested using an A-B-A design. She was instructed to ambulate around an indoor track at her preferred walking velocity and stop when she first noted the onset of pain or when she reached her predetermined ending-time of 5 min. Her sequence was “no tape”, “tape” and “no tape” at each session. She was tested on 5 separate days over a 3-week period of time.
3.1. Data reduction and analysis
A digital stopwatch was used to record the time to onset of pain during ambulation or the predetermined ending time. Descriptive statistics including means and standard devia-tions of data were computed for both cases. The data were entered into Microsoft Excel and graphs were constructed for visual analysis. Visual graphic analysis can be difficult if serial dependency exists. Serial dependency is the con-cept that repeated measures in a single subject are interde-pendent or related to each other. If a significant degree of serial dependency exists, visual and statistical analysis in-terpretation can be compromised. A lag-1 autocorrelation
coefficient was used to determine the presence of any serial dependency[37]. Data were compared using the Two Stan-dard Deviation Band method with statistical significance set at the 0.05 level[37,38].
An advantage of the Two Standard Deviation Band method of analysis is that it can be applied when there are a small number of data points without serial dependency. In-terpretation of statistical significance is made by observing the number of contiguous data points outside of the Two Standard Deviation Band. If at least two contiguous points fall outside the band, a statistically significant response from the treatment is evident at the 0.05 level[37,38].
4. Results
Mean and standard deviation values of the time to onset of pain or predetermined ending-time are listed inTable 1. Lag-1 autocorrelation coefficients were computed for “no tape” and “tape” conditions for case one, since six trials were available for each condition. Barlett’s test[37]indicated that neither the “no tape” nor “tape” condition revealed any se-rial dependency. Similar testing was conducted on case two but since each condition consisted of only five trials, the autocorrelation coefficient was computed across the entire data set as suggested by Ottenbacher[37]. The results again indicated no serial dependency and therefore visual and sta-tistical analysis would not be compromised. Autocorrelation coefficient values are listed inTable 2.
Visual graphic analysis revealed that the taped conditions for both cases appeared to allow each individual to walk a longer period of time before the onset of pain. The Two Standard Deviation Band method revealed statistical signif-icance at the 0.05 level.Plates 1 and 2, display the response to arch taping.
Table 1
Mean, and S.D. values for time to onset of pain (in minutes)
Case one Case two
No tape Tape No tape Tape No tape
Mean 1.43 7.50 0.08 3.70 0.29
S.D. 0.70 0.55 0.18 1.78 0.55
Table 2
Results of calculations for serial dependency Cases Autocorrelation value Barlett’s number Case one No tape 0.46 0.82 No significant serial dependency Tape 0.60 0.82 Case two No tape+tape+no tape combined 0.10 0.52 No significant serial dependency
Plate 1. Case one: Two Standard Deviation Band analysis (±2S.D.).
Plate 2. Case two: Two Standard Deviation Band analysis (±2S.D.).
5. Discussion
Single-subject design studies have the capability of assessing treatment effectiveness within the clinical envi-ronment. This approach can be beneficial in substantiating effective treatment options. Basic to the process and in-terpretation are repeated measures that are stable and lack serial dependency [37]. Analysis of the data for both cases
demonstrated lack of serial dependency and stable data, except case two where the “taping” demonstrated the most variation. This could have been due to a variety of reasons including previous ambulation during that day or difference in application of tape tension. The Two Standard Devia-tion Band method indicated statistical significance at the 0.05 level. The difference in level of response as depicted in the graphs was quite noticeable across all trials and
indicated a reduction in pain during ambulation for both cases.
The development of heel pain from plantar fascial strain appears dependent on the ability of the tissues to handle forces generated during weight bearing activities. When these forces exceed the tissue’s strength capability, mi-crotears occur resulting in an inflammatory process. This inflammatory state may develop into a degenerative process if inadequate healing occurs with continued strain to the plantar fascial tissues. This explains why some are now re-ferring to the chronic condition as a fasciosis as opposed to a fasciitis. It would seem that if weight bearing forces could be controlled to more tissue-tolerant levels, then the normal healing process could take place with minimal negative impact on weight bearing activities.
The taping technique utilized with these two cases may have helped to prevent arch collapse and elongation of the foot during the first part of stance. Case one specifically described her pain to be most intense during the first half of the stance phase. This could have been associated with greater arch collapse resulting in more strain on the plantar fascia as the foot elongates in weight bearing. The tape may also simulate the windlass effect normally produced by the plantar fascia. The application of the tape that wraps around the posterior heel and anchors just distal to the metatarsal heads seems to control the posterior and superior migration of the calcaneus throughout stance and particularly during terminal stance. The windlass effect produced by the tape might reduce the tensile forces on the plantar fascia and thus reduce pain. Case two specifically described her pain to peak during the latter part of stance and this may be an example of the combined influence of the pull of the soleus and gastrocnemius muscles and the windlass effect at the metatarsophalangeal joints during this part of the gait cycle. The slower healing time for dense connective tissue, as discussed in the literature, was supported by these two cases. Case one stated that she taped her arch daily for 8 weeks at which time her pain resolved. After that time, she stated that she only taped her arch in situations when she anticipated prolonged ambulation or weight bearing. She continued to be pain free at 14 months post initiation of taping. Case two taped her arch daily for 16 weeks in order to totally resolve her pain. She continued to be pain free 11 months after instituting arch taping and had even started to run for exercise once again. Both cases noted considerable reduction of pain with arch taping as compared to prior treatment approaches that had been offered to them.
The purpose of the clinical component of this paper was to determine if a modified “double-X” arch taping technique could be effective in controlling pain during ambulation. The results of a single-subject analysis such as used in this study must be appropriately interpreted. The primary purpose of a single-subject design is to evaluate the effectiveness of in-tervention by documenting a patient’s response to treatment
[37]. Conclusions regarding effectiveness of treatment are based on the response of each individual subject under
spe-cific conditions. Subjecting multiple subjects to the same conditions can enhance external validity and thus strengthen the ability to generalize to other subjects. Strength of gen-eralization increases as the number of subjects in a study increases and also when different clinicians are involved.
6. Conclusions
From the current data collected and its relationship with previous literature and studies reported, the described arch taping technique appears effective in controlling pain and improving ambulation and could be considered in similar case scenarios. The need to control tissue strain in plantar fascial tissues for an extended period of time is evident as well. Total pain resolution for these two cases took 8 and 11 weeks of taping, respectively. This supports the slower healing time of dense connective tissue and needs to be considered when managing this type of problem. Further case studies following this testing protocol performed by a variety of clinicians in different environments will help to determine how well one can generalize the effectiveness of this treatment option for plantar fascial heel pain.
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