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The Effect of Subtalar Joint Position on Dorsiflexion of the Ankle/Rearfoot Versus Midfoot/Forefoot During Gastrocnemius Stretching Marie A. Johanson, Amy DeArment, Krystol Hines, Erin Riley, Meghan Martin, Justin Thomas and Kathleen Geist Foot Ankle Int 2014 35: 63 originally published online 20 November 2013 DOI: 10.1177/1071100713513433 The online version of this article can be found at: http://fai.sagepub.com/content/35/1/63
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FAIXXX10.1177/1071100713513433Foot & Ankle InternationalJohanson et al
Article
The Effect of Subtalar Joint Position on Dorsiflexion of the Ankle/Rearfoot Versus Midfoot/Forefoot During Gastrocnemius Stretching
Foot & Ankle International 2014, Vol 35(1) 63–70 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100713513433 fai.sagepub.com
Marie A. Johanson, PT, PhD, OCS1, Amy DeArment, DPT1, Krystol Hines, DPT1, Erin Riley, DPT1, Meghan Martin, DPT1, Justin Thomas, DPT1, and Kathleen Geist, PT, DPT, OCS, COMT1
Abstract Background: Limited ankle joint dorsiflexion passive range of motion (PROM) has been associated with common chronic lower extremity conditions, and clinicians often instruct patients in stretching exercises to increase dorsiflexion. However, little is known about how subtalar joint (STJ) position affects dorsiflexion at the midfoot/forefoot versus ankle/rearfoot during gastrocnemius stretching. The purpose of this study was to determine if more dorsiflexion occurs at the ankle/ rearfoot and less at the midfoot/forefoot during gastrocnemius stretching with the STJ positioned in supination versus pronation. Methods: In this repeated measures design, 27 participants (23 females, 4 males; mean age = 31.3 years, SD = 10.7) with current or recent history of lower extremity chronic conditions and less than 10 degrees ankle dorsiflexion measured with the knee in extension on the involved side(s) performed five 30-second gastrocnemius stretching trials in pronation and supination on each side in a randomly determined sequence. A 7-camera Vicon Motion Analysis System and an AMTI force plate were used to measure midfoot/forefoot dorsiflexion, ankle/rearfoot dorsiflexion, knee extension, and normalized vertical ground reaction force. Results: Two-way repeated measures ANOVA revealed a significant increase in midfoot/forefoot dorsiflexion when stretching in pronation compared to supination (P < .001). ANOVAs also demonstrated significantly more extension of the knee when stretching in supination compared to pronation (P < .001), and increased normalized vertical ground reaction force when stretching in supination compared to pronation (P = .032). With the numbers available, no significant difference in ankle/rearfoot dorsiflexion when stretching in supination compared to pronation could be detected (P > .05). Conclusion: Gastrocnemius stretching in pronation resulted in more dorsiflexion at the midfoot/forefoot than stretching in supination. Clinical Relevance: Clinicians may want to consider STJ position during gastrocnemius stretching to either facilitate or limit recruitment of dorsiflexion motion at the midfoot/forefoot. Keywords: ankle dorsiflexion, gastrocnemius stretching, subtalar joint Limited ankle joint dorsiflexion passive range of motion (PROM) has been associated with common cumulative trauma injuries and other chronic conditions of the lower extremity, including Achilles tendonitis,20,38 plantar fasciitis,21,31 medial tibial stress syndrome,24,38 iliotibial band friction syndrome,25 patellofemoral pain syndrome,25 chronic ankle instability,30 and tibial stress fractures.11 Clinicians commonly institute gastrocnemius stretching programs when patients exhibit limited ankle dorsiflexion PROM with the knee in an extended position, as this finding typically indicates decreased gastrocnemius extensibility.32 Some clinicians instruct their patients to perform gastrocnemius
stretching with the subtalar joint (STJ) positioned in supination (or neutral) because of the potential for dorsiflexion at the subtalar and midtarsal joints when the stretching is performed with the STJ in pronation.4,19 We use the terms supination and pronation at the STJ to describe the composite 1
Emory University School of Medicine, Atlanta, GA, USA
Corresponding Author: Marie A. Johanson, PT, PhD, OCS, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, 1462 Clifton Rd, NE, Atlanta, GA 30322, USA. Email: [email protected]
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triplane motions at this joint that include the frontal plane component of inversion and eversion.22 Increases in dorsiflexion range of motion following a stretching program may mitigate compensatory changes in gait resulting from limited dorsiflexion. During the stance phase of gait, maximum dorsiflexion of 8 to 10 degrees beyond neutral occurs just before heel-off when the knee is close to full extension.17,22,28 Therefore, tightness of the gastrocnemius muscle may limit normal advancement of the tibia relative to the foot during the midstance phase of gait.22,35 To achieve advancement of the tibia when ankle dorsiflexion is limited, compensatory movements at joints proximal or distal to the ankle may occur, including the subtalar and midtarsal joints.19,21,22 Because the gastrocnemius muscle crosses both the knee and ankle joints, knee position can influence ankle dorsiflexion. When the knee is fully extended, ankle dorsiflexion is typically more limited than when the knee joint is flexed.32 When the STJ is pronated, the 2 axes of the talonavicular and calcanealcuboid articulations that compose the midtarsal joint are positioned more parallel to each other allowing more mobility at the midfoot, often described as the “unlocked” position.10,12,22 When the STJ is pronated during weight bearing activities, dorsiflexion can occur at the subtalar and midtarsal joints, as well as, the talocrural joint. Thus, increased subtalar pronation before heel-off can compensate for limited dorsiflexion at the talocrural joint.8,19,21 Excessive pronation at the STJ and midtarsal joint is one theorized mechanism by which limited ankle dorsiflexion contributes to lower extremity cumulative trauma injuries.19,21,22 Pronation due to limited gastrocnemius extensibility may place excessive stress on the plantar fascia,1,21,25,33 contributing to the development of plantar fasciitis. Pronation due to limited gastrocnemius extensibility also may increase eccentric contraction of the soleus and posterior tibialis muscles which are often associated with medial tibial stress syndrome.3,38 Previous investigators have shown that gastrocnemius stretching performed with the STJ in supination and pronation both increase ankle dorsiflexion PROM.13,39 Previous investigators have also shown that increased ankle dorsiflexion PROM following gastrocnemius stretching does not increase ankle dorsiflexion during gait.14,16 However, methods used in these previous studies could not differentiate dorsiflexion occurring at the ankle and rearfoot from dorsiflexion occurring at the midfoot. Though stretching with the STJ in supination and pronation both resulted in increased ankle dorsiflexion, the motion could have been gained mostly at the ankle and rearfoot or mostly at the midfoot. Knowledge about which joints contribute to increased dorsiflexion following stretching could help clinicians identify the most optimal stretching technique for a given patient. However, little is known about the effect of STJ position on dorsiflexion at the ankle/rearfoot versus the midfoot during stretching exercises.
The purpose of this study was to determine if individuals with current or recent history of lower extremity chronic conditions and tightness of the gastrocnemius muscle demonstrate more dorsiflexion at the ankle/rearfoot and less dorsiflexion at the midfoot during gastrocnemius stretching with the STJ positioned in supination compared to pronation. Our hypothesis was that when stretching with the STJ positioned in pronation, participants would exhibit more dorsiflexion at the midfoot and less at the ankle joint/rearfoot than when stretching with the STJ positioned in supination.
Materials and Methods Study Design This study used a repeated measures design. The repeated measures were stretching position (pronation, supination) and side (right, left).
Participants Twenty-seven individuals including 4 males and 23 females (mean age = 31.3 years, SD = 10.7) with a current or recent history of lower extremity chronic conditions associated with limited ankle dorsiflexion were recruited to participate in the study. Participants were recruited from a university and running clubs in the metropolitan Atlanta area. Inclusion criteria included (1) age between 18 and 55 years, (2) current or recent history (within 2 years) of lower extremity chronic condition(s) associated with limited ankle dorsiflexion, (3) less than 10 degrees of passive ankle dorsiflexion PROM of the involved extremity(ies), measured with the knee extended, (4) ankle dorsiflexion PROM with the knee flexed at least 5 degrees greater than with the knee extended, and (5) ability to ambulate barefoot without an assistive device. Potential participants were excluded if they had (1) a knee flexion contraction greater than 5 degrees, (2) a leg length difference of greater than 2 cm, (3) a history of systemic neurological condition, arthritic condition, bony or peripheral nerve trauma, or surgery intervention involving the lower extremities, (4) a history of a soft tissue injury of the lower extremity (eg, ankle, sprain) within 6 months of participation in the study, or (5) a reported pain greater than 0/10 while walking in bare feet. Potential participants were also excluded if they were currently receiving treatment for their lower extremity condition.
Instrumentation A 7-camera Vicon Motion Analysis System (Vicon, Oxford Metrics Group, Oxford, UK) and Vicon Nexus software were used to measure positions of retro-reflective markers
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Johanson et al attached to the lower limbs during stretching. Camera frequency was set at 100 Hz. An AMTI (Advance Medical Technology, Inc, Watertown, MA, USA) force plate recessed in the center of an elevated floor and integrated with the motion analysis system was used to measure ground reaction forces during stretching. The frequency of the force place was also set at 100 Hz. Vicon is considered a reliable system for the collection of kinematic data.18,34 Vicon’s standard lower extremity gait template (Plug-In Gait, Vicon, Oxford Metrics Group, Oxford, UK) in conjunction with the Oxford Foot Model template (Vicon, Oxford Metrics Group, Oxford, UK) and integrated with the force plate were used to analyze kinematic and kinetic variables during static stretching. The Oxford Foot Model is a reliable model for study of the foot and ankle5,7,23,34,36 and was used to differentiate dorsiflexion of the ankle and rearfoot from dorsiflexion at the midfoot and forefoot during static stretching.
Procedures Screening measurements. Except for eligibility criteria related to PROM and leg length, participants were initially screened by questionnaire via telephone, email, or face-toface interaction. If eligible on the basis of the initial screen, ankle dorsiflexion PROM with the knee extended and with the knee flexed was measured to further determine eligibility for the study as described below. All eligible participants who agreed to participate signed an informed consent form and rights of the participants were protected. Participants were randomly assigned to the order of side to be tested (involved/uninvolved for participants with unilateral involvement and right/left for participants with bilateral involvement) and dorsiflexion PROM measurement position (knee extended/flexed). The order of side and STJ position (pronation/supination) during motion analysis of participants’ stretching were also determined by random sequencing at this time. PROM of ankle dorsiflexion with the knee extended was measured with participants in prone and the foot off the end of the plinth.13 One investigator used a goniometer aligned to midlines drawn on the posterior calf and calcaneus to monitor the degree of varus/valgus at the STJ. This investigator maintained the STJ position in the anatomical zero position or at the end range of eversion PROM and also observed the knee joint to ensure an extended position. A second investigator aligned the stationary arm of a blinded goniometer with the fibular head and the moving arm over the fifth metatarsal. The investigator then applied passive force against the plantar aspect of the participant’s midfoot and forefoot in the direction of dorsiflexion. The first investigator read and documented the angle obtained. Passive dorsiflexion range of motion with the knee in a flexed position was measured in the same manner described
above, except the knee was flexed to 90 degrees. Ankle dorsiflexion PROM measurements were taken 3 times to assess intrarater reliability and the average of the 3 measurements was recorded. Ankle dorsiflexion PROM measurements were repeated by a second examiner on every third participant to assess interrater reliability. Leg length was assessed using a standard tape measure method measured with the participant in a supine position.29 Other measurements. STJ PROM, forefoot position and standing rearfoot angle were also measured. Forefoot position was measured in prone by aligning 1 arm of the goniometer parallel to the plane of the metatarsal heads, and the other arm perpendicular to the line on the posterior calcaneus mentioned previously, while keeping the STJ in neutral.29 To measure rearfoot angle, participants were asked to stand in a relaxed position while an investigator matched the lines of a goniometer to the midlines drawn on the posterior aspect of the calcaneus and calf.15 The Vicon system was calibrated using a wand calibration procedure.37 The Oxford Foot Model marker set was used in addition to Vicon’s standard lower extremity Plug-In Gait marker set (Figure 1). Reflective markers were applied to participants’ sacrum and bilaterally over the (1) Posterior Superior Iliac Spine (PSIS), (2) Anterior Superior Iliac spine (ASIS), (3) lateral thigh, (4) lateral aspect of the knee joint, (5) fibular head, (6) tibial tuberosity, (7) lateral calf, (8) anterior tibia, (9) lateral malleolus, (10) lateral calcaneus, (11) superior aspect of the posterior calcaneus, (12) midportion of the posterior calcaneus on a peg, (13) distal aspect of the posterior calcaneus, (14) proximal fifth metatarsal, (15) distal fifth metatarsal, (16) hallux, (17) distal aspect of the second metatarsal, (18) medial aspect of the distal first metatarsal, (19) dorsal aspect of the distal first metatarsal, (20) proximal first metatarsal, (21) medial malleolus, and (22) sustentaculum tali. Prior to the stretching trials, a static trial was collected. The participant stood on the force plate in relaxed standing for 5 seconds. Six foot markers, used only in the static trials, were removed prior to the stretching trials.34 A 15-degree wedge was constructed using three 5-degree beveled posting strips (Orthofeet Inc, Northvail, NJ, USA) affixed to one another. The posting strips were made of ethyl vinyl acetate with a manufacturer durometer A reading in the 50 to 60 range. The subject’s foot length was measured while standing with a standard tape measure to customize the length of each of the 3 wedges. The adhesive backings on the bottom of the wedges were removed, and they were aligned to create the desired 15-degree angle. The final wedge was affixed to a 56 cm × 35.5 cm poster board to create the template. Nonskid material was applied to the bottom of the template to allow for greater surface stability during stretching. The position of the template on the force plate was standardized by aligning the bottom of the
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Figure 2a. Participant stretching in supination using template on the left side.
Figure 1. Marker placement, anterior view.
template with the base of the force plate. This position was maintained by affixing the template on the floor with painter’s tape. The force plate was calibrated with the template in position before beginning data collection of the subjects’ stretching trials. In standing, participants were instructed to place the side to be stretched on the template with the 15-degree wedge over the force plate and perform a standard gastrocnemius stretching exercise (Figures 2a and 2b). Order of side and STJ position were determined by the previously established random sequence. The participants were instructed to align the medial side of their foot with the raised edge of the template when stretching in supination and to align the lateral side of their foot up with the raised edge of the template when stretching in pronation. Participants were then instructed to place their hands on an adjustable height walker for support in front of them, with 1 foot forward and 1 behind. The participants self-selected the position of the leading foot and leaned their trunk toward the walker, shifting their weight over the
Figure 2b. Posterior view of participant’s left foot stretching in pronation using template.
front foot, while straightening the knee of the back leg and maintaining contact of the heel of the back foot with the wedge (Figure 2a).9 During stretching the participants were instructed to feel slight discomfort to achieve an adequate stretch. The gastrocnemius stretching position was held for 30 seconds for 5 trials on each side in both pronation and supination in the randomly determined sequence for a total of 20 stretches. The parameters of the stretching exercises were based on previous investigator data regarding hamstring stretching exercises.2 Participants were allowed a 10-second rest period between stretches. Data processing. Marker trajectory gaps of 5 frames or less were interpolated using Woltrin Quintic spline. Marker paths were smoothed using a Woltering filter (Vicon, Oxford Metrics Group, Oxford, UK). Vicon software was then used to calculate segment angles and ground reaction
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Johanson et al Table 1. Participants’ Chronic Lower Extremity Injuries. Injury
Frequency
Anterior compartment syndrome Patellofemoral pain syndrome (PFPS) Plantar fasciitis Anterolateral shin splints Posteromedial shin splints Chronic ankle sprains Tibial stress fracture Involved Side Left Right Bilateral
1 2 6 7 5 4 2
Table 2. Participants’ Ankle Dorsiflexion Passive Range of Motion. Knee Position
Degrees (SD)
Knee extended Left Right Knee flexed Left Right
4.6 (2.9) 4.6 (4.1) 16.0 (5.7) 15.9 (6.4)
Frequency 6 10 11
Table 3. Joint Angles and Normalized Vertical Ground Reaction Force (GRF) During Stretching in Pronation and Supination. Variable
forces (Plug-In Gait and Oxford Foot Model, Vicon, Oxford Metrics Group, Oxford, UK). Using manual start and stop times for collection of the data during the stretching trials resulted in collection of slightly over 30 seconds of data (slightly more than 3000 frames). To consistently examine data across the different trials, the middle 3000 frames were analyzed, corresponding to the middle 30 seconds of the stretching trials. Means were calculated across the 30 seconds (3000 frames) for the following sagittal plane segment angles: (1) tibia to femur, (2) ankle/rearfoot to tibia, and (3) midfoot/forefoot to ankle/rearfoot. The vertical ground reaction force was normalized to body mass and the average also calculated across the 30 seconds. Averages from 3 trials from each of the stretching positions were used in the statistical analyses. Statistical analysis. Intraclass correlation coefficients (ICCs) were used to assess intrarater and interrater reliability of ankle dorsiflexion PROM with knee extended and knee flexed. Descriptive statistics were calculated for subject characteristics and dependent variables using means and standard deviations for continuous variables, and using frequencies for categorical variables. Normality of distribution and homogeneity of variance of dependent variables were assessed with Shapiro–Wilk and Levene’s tests, respectively. Two-way repeated measures ANOVA were used to assess differences between stretching position (pronation and supination) and side (right and left) for each dependent variable.
Results Participants’ chronic lower extremity injuries and side(s) of injury are reported in Table 1. Participants’ ankle dorsiflexion PROM measurements are summarized in Table 2. Descriptive statistics (means and standard deviations) of dependent variables are reported in Table 3, and a comparison of dorsiflexion at the midfoot/forefoot and ankle/
Pronation a
Peak average vertical GRF Left Right Knee extension Left Right Ankle/rearfoot dorsiflexion Left Right Midfoot/forefoot dorsiflexion Left Right
49.79 (4.12) 49.71 (3.93) 4.09 (7.22) 6.72 (6.71) 32.39 (9.25) 31.00 (8.09) 0.21 (8.21) 3.16 (8.16)
Supination 51.13 (4.97) 50.31 (4.01) 1.72 (8.27) 4.48 (6.67) 32.55 (10.88) 34.85 (9.09) –3.56 (8.50) –0.40 (9.10)
Values are reported as means and standard deviations. a Normalized to body mass.
rearfoot for the 2 stretching position (pronation and supination) is shown in Figure 3. Intrarater and interrater ICC values for ankle dorsiflexion PROM with the knee flexed and extended ranged from .94 to .98 and from .85 to .98, respectively. Normality of distribution and homogeneity of variance of dependent variables were established with the Shapiro–Wilk test and Levene’s test, respectively. Two-way repeated measures ANOVA revealed a significant increase in midfoot/forefoot dorsiflexion when stretching in pronation than when stretching in supination, F(1, 26) = 51.648, P < .001. ANOVAs also demonstrated significant increases in normalized vertical ground reaction force when stretching in supination compared to pronation, F(1, 26) = 5.126, P = .032, and more extension of the knee when stretching in supination compared to pronation, F(1, 26) = 29.102, P < .001. With the numbers available, no significant main effect of order of side, ground reaction force, ankle/ rearfoot dorsiflexion, or midfoot/forefoot dorsiflexion could be detected (P > .05). With the numbers available, no significant main effect for position for ankle/rearfoot dorsiflexion (P > .05) or significant side by position interactions could be detected (P > .05).
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Midfoot/Forefoot Dorsiflexion (Degrees)
4
Le
Right
3 1.66
2 1 0 -1
-1.38 -2.13
-2 -3 -4 -4.97
-5 -6
Supinaon
Pronaon Stretching Posion
Figure 3. Midfoot/forefoot dorsiflexion stretching in pronation and supination (means and standard error).
Discussion Our finding of increased midfoot/forefoot dorsiflexion when stretching with the STJ positioned in pronation compared to supination is consistent with accepted biomechanical principles related to the foot and ankle. This, however, is the first experimental demonstration of the more theoretical biomechanical hypotheses. When the STJ supinates, motion at the midtarsal joint (MTJ) is restricted to supination.27 With the STJ and MTJ positioned in supination, the sagittal plane component of pronation (dorsiflexion) would be primarily confined to the talocrural joint. This is supported by our finding of less dorsiflexion at the midfoot/forefoot when participants stretched with the STJ in supination versus pronation. Conversely, when the STJ pronates, the MTJ joint is free to move into pronation as well.27 With the STJ and MTJ in pronation, these joints contribute to the sagittal plane component of pronation (dorsiflexion) as well as the talocrural joint. This is supported by our finding of increased midfoot/forefoot dorsiflexion when participants stretched with the STJ in pronation versus supination. We believe this is an important finding because, to our knowledge, this is the only study that has directly demonstrated increased motion at the midfoot when stretching in pronation. Clinicians may specifically choose to instruct a patient to stretch in supination or pronation, depending on whether motion at the midfoot would best be limited or facilitated for a particular individual. Though we found more dorsiflexion at the ankle/rearfoot when participants stretched in supination compared to pronation (Table 3), with the numbers available, no statistically significant difference could be detected. Our marker set did not allow us to differentiate dorsiflexion occurring at the STJ from dorsiflexion occurring at the talocrural joint. Thus, it is possible that the nonsignificant but increased dorsiflexion at
the ankle/rearfoot represented increased dorsiflexion at the talocrural joint and decreased dorsiflexion at the STJ. We believe biomechanical determinants also underlie our finding that maximum knee extension was significantly increased when participants stretched with the STJ in supination compared to pronation. Because the ankle mortise is so congruent, motion of the talus cannot be accommodated within the mortise and therefore, motion of the tibia is concomitant with STJ motion. The tibia externally rotates when the STJ supinates and conversely, internally rotates when the STJ pronates.27 However, at the knee joint, tibial external rotation is required for full knee extension; this tibial external rotation is commonly called the “screw home mechanism.”6,26 Since we instructed participants to maintain the knee in extension during the stretch, it is apparent that they could not maintain full extension when stretching with the STJ in pronation, because the tibial internal rotation that accompanies STJ pronation precluded the necessary tibial external rotation needed to achieve full knee extension. When stretching with the STJ in supination, the tibial external rotation that accompanies STJ supination facilitated the “screw-home mechanism” and participants were able to maintain the knee is greater extension. Another factor to consider when contrasting the findings at the knee and ankle/rearfoot is that because of the greater knee extension when stretching in supination, participants would be expected to have less ankle/rearfoot dorsiflexion due to passive insufficiency of the gastrocnemius. The ankle/rearfoot dorsiflexion was increased when participants stretched with a more extended knee in STJ supination, though with the numbers available, no significant difference could be detected. Participants’ vertical average ground reaction force was greater when stretching in supination than pronation, which may have contributed to the increase in ankle/rearfoot dorsiflexion (though not significant) when stretching in supination. Vertical ground reaction force would be expected to vary with the degree of dorsiflexion angle. However, with greater dorsiflexion, the vertical component would be expected to decrease, not increase. We did not quantify level of comfort during the stretching, so a difference in degree of comfort between the stretching positions could explain the vertical ground reaction force findings. If participants were less comfortable stretching in pronation, they might have exerted less force. The difference in ground reaction force is also interesting in light of findings at the midfoot/forefoot. Even though vertical ground reaction force was lower when stretching in pronation, participants exhibited more dorsiflexion at the midfoot/forefoot. Thus, increased midfoot motion when stretching in pronation is not likely attributable to increased force.
Limitations We did not quantify degree of discomfort during the 2 different stretching positions, so a difference in level of
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Johanson et al comfort could account for some of our study findings. We also did not control for foot type or injury type. Individuals with structural findings of pes planus, hypermobility syndrome, or pes cavus may not respond similarly when stretching in STJ supination versus pronation, and future research is needed to specifically study stretching positions among these specific populations. Similarly, patients with different chronic conditions of the lower extremity may not exhibit the same patterns when stretching with the STJ in different positions. Though we measured vertical ground reaction force, we did not control force exerted during the stretching. The majority of our sample was female, so it is possible that our study findings would have differed if more males were included in our sample. Finally, low power could account for the lack of statistically significant findings at the ankle/rearfoot between the stretching positions.
Conclusion Gastrocnemius stretching performed with the STJ positioned in pronation resulted in more dorsiflexion at the midfoot/forefoot than stretching with the STJ in supination but did not affect the amount of dorsiflexion occurring at the ankle/rearfoot. Stretching with the STJ in supination was also accompanied by greater extension at the knee and greater vertical ground reaction force. Clinicians may want to consider STJ position during gastrocnemius stretching to either facilitate or limit recruitment of dorsiflexion motion at the midfoot/forefoot. Acknowledgments We would like to thank Jeanne Charles, PT, PhD, MSW, for technical support and Trisha Kesar, PT, PhD, for editorial assistance.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the Physical Therapy Association of Georgia.
References 1. Amis J, Jennings L, Graham D, Graham CE. Painful heel syndrome: radiographic and treatment assessment. Foot Ankle. 1988;9:91-95. 2. Bandy WD, Irion JM, Briggler M. The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Phys Ther. 1997;77:1090-1096. 3. Bates P. Shin splints—a literature review. Br J Sports Med. 1985;19:132-137. 4. Bohannon RW, Tiberio D, Waters G. Motion measured from forefoot and hindfoot landmarks during passive ankle
dorsiflexion range of motion. J Orthop Sports Phys Ther. 1991;13:20-22. 5. Carson MC, Harrington ME, Thompson N, et al. Kinematic analysis of a multi-segment foot model for research and clinical applications: a repeatability analysis. J Biomech. 2001;34:1299-1307. 6. Caruntu DI, Hefzy MS. 3-D anatomically based dynamic modeling of the human knee to include tibio-femoral and patello-femoral joints. J Biomech Eng. 2004;126:44-53. 7. Curtis DJ, Bencke J, Stebbins JA, Stansfield B. Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait. Gait Posture. 2009;30:118-121. 8. Donatelli RA, Wooden MJ. Biomechanical orthotics. In: Donatelli RA, eds. The Biomechanics of the Foot and Ankle. Philadelphia, PA: F. A. Davis; 1996:255-279. 9. Dutton M. Orthopaedic Examination, Evaluation, and Intervention. New York, NY: McGraw-Hill; 2008. 10. Elftman H. The transverse tarsal joint and its control. Clin Orthop. 1960;16:41-44. 11. Fredericson M. Common injuries in runners. Diagnosis, rehabilitation and prevention. Sports Med. 1996;21:49-72. 12. Gersham S. A literature review of midtarsal joint function. Clin Podriatr Med Surg. 1988;5:385-391. 13. Johanson M, Baer J, Hovermale H, Phouthavong P. Subtalar joint position during gastrocnemius stretching and ankle dorsiflexion range of motion. J Athl Train. 2008;43:172-178. 14. Johanson MA, Cuda BJ, Koontz JE, et al. Effect of stretching on ankle and knee angles and gastrocnemius activity during the stance phase of gait. J Sport Rehabil. 2009;18:521-534. 15. Johanson MA, Greenfeld L, Hung C, et al. The relationship between forefoot and rearfoot static alignment in pain-free individuals with above-average forefoot varus angles. Foot Ankle Spec. 2010;3:112-116. 16. Johanson MA, Wooden M., Catlin PA, et al. Effects of gastrocnemius stretching on ankle dorsiflexion and time-to-heel-off during the stance phase of gait. Phys Ther Sport. 2006;7:93-100. 17. Jordan RP. Ankle dorsiflexion at the heel-off phase of gait. J Am Podiatry Assoc. 1979;69:40-46. 18. Kadaba MP, Ramakrishnan HK, Wootten ME, et al. Repeatability of kinematic, kinetic, and electromyographic data in normal adult gait. J Orthop Res. 1989;7:849-860. 19. Karas M, Hoy DJ. Compensatory midfoot dorsiflexion in the individual with heelcord tightness: implications for orthotic device designs. J Prosthet Orthot. 2002;14:82-93. 20. Kaufman KR, Brodine SK, Shaffer RA, et al. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med. 1999;27:585-593. 21. Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med. 1991;19:66-71. 22. Levangie PK, Norkin CC. Joint Structure & Function: A Comprehensive Analysis. Philadelphia, PA: F. A. Davis; 2011. 23. Levinger P, Murley GS, Barton CJ, et al. A comparison of foot kinematics in people with normal- and flat-arched feet using the Oxford foot model. Gait Posture. 2010;32:519-523. 24. Lilletvedt J, Kreighbaum E, Phillips RL. Analysis of selected alignment of the lower extremity related to the shin splint syndrome. J Am Podiatry Assoc. 1979;69:211-217.
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25. Messier SP, Pittala KA. Etiologic factors associated with selected running injuries. Med Sci Sports Exerc. 1988;20:501-505. 26. Moglo KE, Shirazi-Adl A. Cruciate coupling and screw-home mechanism in passive knee joint during extension–flexion. J Biomech. 2005;38:1075-1083. 27. Mueller MJ. The ankle and foot complex. In: Levangie PK, Norkin CC, eds. Joint Structure & Function: A Comprehensive Analysis. Philadelphia, PA: F. A. Davis; 2005:437-477. 28. Murray MP, Kory RC, Clarkson BH, Sepic SB. Comparison of free and fast speed walking patterns of normal men. Am J Phys Med. 1966;45:8-23. 29. Palmer ML, Epler ME. Fundamentals of Musculoskeletal Assessment Techniques. Philadelphia, PA: Lippincott; 1998. 30. Pope R, Herbert R, Kirwan J. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Aust J Physiother. 1998;44:165-172. 31. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: a matched case-control study. J Bone Joint Surg Am. 2003;85-A:872-877. 32. Riemann BL, DeMont RG, Ryu K, Lephart SM. The effects of sex, joint angle, and the gastrocnemius muscle on
passive ankle joint complex stiffness. J Athl Train. 2001;36: 369-375. 33. Schepsis AA, Leach RE, Gorzyca J. Plantar fasciitis. Etiology, treatment, surgical results, and review of the literature. Clin Orthop Relat Res. 1991;(266):185-196. 34. Stebbins J, Harrington M, Thompson N, et al. Repeatability of a model for measuring multi-segment foot kinematics in children. Gait Posture. 2006;23:401-410. 35. Subotnick SI. Equinus deformity as it affects the forefoot. J Am Podiatry Assoc. 1971;61:423-427. 36. Theologis TN, Harrington ME, Thompson N, Benson MK. Dynamic foot movement in children treated for congenital talipes equinovarus. J Bone Joint Surg Br. 2003;85:572-577. 37. Vicon Motion System. The Vicon Manual. Lake Forest, CA: Vicon Motion System; 2002. 38. Wilder RP, Sethi S. Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints. Clin Sports Med. 2004;23:55-81, vi. 39. Worrell TW, McCullough M, Pfeiffer A. Effect of foot position on gastrocnemius/soleus stretching in subjects with normal flexibility. J Orthop Sports Phys Ther. 1994;19:352-356.
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The Effect of Subtalar Joint Position on Dorsiflexion of the Ankle/Rearfoot Versus Midfoot/Forefoot During Gastrocnemius Stretching Marie A. Johanson, Amy DeArment, Krystol Hines, Erin Riley, Meghan Martin, Justin Thomas and Kathleen Geist Foot Ankle Int 2014 35: 63 originally published online 20 November 2013 DOI: 10.1177/1071100713513433 The online version of this article can be found at: http://fai.sagepub.com/content/35/1/63
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FAIXXX10.1177/1071100713513433Foot & Ankle InternationalJohanson et al
Article
The Effect of Subtalar Joint Position on Dorsiflexion of the Ankle/Rearfoot Versus Midfoot/Forefoot During Gastrocnemius Stretching
Foot & Ankle International 2014, Vol 35(1) 63–70 © The Author(s) 2013 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100713513433 fai.sagepub.com
Marie A. Johanson, PT, PhD, OCS1, Amy DeArment, DPT1, Krystol Hines, DPT1, Erin Riley, DPT1, Meghan Martin, DPT1, Justin Thomas, DPT1, and Kathleen Geist, PT, DPT, OCS, COMT1
Abstract Background: Limited ankle joint dorsiflexion passive range of motion (PROM) has been associated with common chronic lower extremity conditions, and clinicians often instruct patients in stretching exercises to increase dorsiflexion. However, little is known about how subtalar joint (STJ) position affects dorsiflexion at the midfoot/forefoot versus ankle/rearfoot during gastrocnemius stretching. The purpose of this study was to determine if more dorsiflexion occurs at the ankle/ rearfoot and less at the midfoot/forefoot during gastrocnemius stretching with the STJ positioned in supination versus pronation. Methods: In this repeated measures design, 27 participants (23 females, 4 males; mean age = 31.3 years, SD = 10.7) with current or recent history of lower extremity chronic conditions and less than 10 degrees ankle dorsiflexion measured with the knee in extension on the involved side(s) performed five 30-second gastrocnemius stretching trials in pronation and supination on each side in a randomly determined sequence. A 7-camera Vicon Motion Analysis System and an AMTI force plate were used to measure midfoot/forefoot dorsiflexion, ankle/rearfoot dorsiflexion, knee extension, and normalized vertical ground reaction force. Results: Two-way repeated measures ANOVA revealed a significant increase in midfoot/forefoot dorsiflexion when stretching in pronation compared to supination (P < .001). ANOVAs also demonstrated significantly more extension of the knee when stretching in supination compared to pronation (P < .001), and increased normalized vertical ground reaction force when stretching in supination compared to pronation (P = .032). With the numbers available, no significant difference in ankle/rearfoot dorsiflexion when stretching in supination compared to pronation could be detected (P > .05). Conclusion: Gastrocnemius stretching in pronation resulted in more dorsiflexion at the midfoot/forefoot than stretching in supination. Clinical Relevance: Clinicians may want to consider STJ position during gastrocnemius stretching to either facilitate or limit recruitment of dorsiflexion motion at the midfoot/forefoot. Keywords: ankle dorsiflexion, gastrocnemius stretching, subtalar joint Limited ankle joint dorsiflexion passive range of motion (PROM) has been associated with common cumulative trauma injuries and other chronic conditions of the lower extremity, including Achilles tendonitis,20,38 plantar fasciitis,21,31 medial tibial stress syndrome,24,38 iliotibial band friction syndrome,25 patellofemoral pain syndrome,25 chronic ankle instability,30 and tibial stress fractures.11 Clinicians commonly institute gastrocnemius stretching programs when patients exhibit limited ankle dorsiflexion PROM with the knee in an extended position, as this finding typically indicates decreased gastrocnemius extensibility.32 Some clinicians instruct their patients to perform gastrocnemius
stretching with the subtalar joint (STJ) positioned in supination (or neutral) because of the potential for dorsiflexion at the subtalar and midtarsal joints when the stretching is performed with the STJ in pronation.4,19 We use the terms supination and pronation at the STJ to describe the composite 1
Emory University School of Medicine, Atlanta, GA, USA
Corresponding Author: Marie A. Johanson, PT, PhD, OCS, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, 1462 Clifton Rd, NE, Atlanta, GA 30322, USA. Email: [email protected]
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triplane motions at this joint that include the frontal plane component of inversion and eversion.22 Increases in dorsiflexion range of motion following a stretching program may mitigate compensatory changes in gait resulting from limited dorsiflexion. During the stance phase of gait, maximum dorsiflexion of 8 to 10 degrees beyond neutral occurs just before heel-off when the knee is close to full extension.17,22,28 Therefore, tightness of the gastrocnemius muscle may limit normal advancement of the tibia relative to the foot during the midstance phase of gait.22,35 To achieve advancement of the tibia when ankle dorsiflexion is limited, compensatory movements at joints proximal or distal to the ankle may occur, including the subtalar and midtarsal joints.19,21,22 Because the gastrocnemius muscle crosses both the knee and ankle joints, knee position can influence ankle dorsiflexion. When the knee is fully extended, ankle dorsiflexion is typically more limited than when the knee joint is flexed.32 When the STJ is pronated, the 2 axes of the talonavicular and calcanealcuboid articulations that compose the midtarsal joint are positioned more parallel to each other allowing more mobility at the midfoot, often described as the “unlocked” position.10,12,22 When the STJ is pronated during weight bearing activities, dorsiflexion can occur at the subtalar and midtarsal joints, as well as, the talocrural joint. Thus, increased subtalar pronation before heel-off can compensate for limited dorsiflexion at the talocrural joint.8,19,21 Excessive pronation at the STJ and midtarsal joint is one theorized mechanism by which limited ankle dorsiflexion contributes to lower extremity cumulative trauma injuries.19,21,22 Pronation due to limited gastrocnemius extensibility may place excessive stress on the plantar fascia,1,21,25,33 contributing to the development of plantar fasciitis. Pronation due to limited gastrocnemius extensibility also may increase eccentric contraction of the soleus and posterior tibialis muscles which are often associated with medial tibial stress syndrome.3,38 Previous investigators have shown that gastrocnemius stretching performed with the STJ in supination and pronation both increase ankle dorsiflexion PROM.13,39 Previous investigators have also shown that increased ankle dorsiflexion PROM following gastrocnemius stretching does not increase ankle dorsiflexion during gait.14,16 However, methods used in these previous studies could not differentiate dorsiflexion occurring at the ankle and rearfoot from dorsiflexion occurring at the midfoot. Though stretching with the STJ in supination and pronation both resulted in increased ankle dorsiflexion, the motion could have been gained mostly at the ankle and rearfoot or mostly at the midfoot. Knowledge about which joints contribute to increased dorsiflexion following stretching could help clinicians identify the most optimal stretching technique for a given patient. However, little is known about the effect of STJ position on dorsiflexion at the ankle/rearfoot versus the midfoot during stretching exercises.
The purpose of this study was to determine if individuals with current or recent history of lower extremity chronic conditions and tightness of the gastrocnemius muscle demonstrate more dorsiflexion at the ankle/rearfoot and less dorsiflexion at the midfoot during gastrocnemius stretching with the STJ positioned in supination compared to pronation. Our hypothesis was that when stretching with the STJ positioned in pronation, participants would exhibit more dorsiflexion at the midfoot and less at the ankle joint/rearfoot than when stretching with the STJ positioned in supination.
Materials and Methods Study Design This study used a repeated measures design. The repeated measures were stretching position (pronation, supination) and side (right, left).
Participants Twenty-seven individuals including 4 males and 23 females (mean age = 31.3 years, SD = 10.7) with a current or recent history of lower extremity chronic conditions associated with limited ankle dorsiflexion were recruited to participate in the study. Participants were recruited from a university and running clubs in the metropolitan Atlanta area. Inclusion criteria included (1) age between 18 and 55 years, (2) current or recent history (within 2 years) of lower extremity chronic condition(s) associated with limited ankle dorsiflexion, (3) less than 10 degrees of passive ankle dorsiflexion PROM of the involved extremity(ies), measured with the knee extended, (4) ankle dorsiflexion PROM with the knee flexed at least 5 degrees greater than with the knee extended, and (5) ability to ambulate barefoot without an assistive device. Potential participants were excluded if they had (1) a knee flexion contraction greater than 5 degrees, (2) a leg length difference of greater than 2 cm, (3) a history of systemic neurological condition, arthritic condition, bony or peripheral nerve trauma, or surgery intervention involving the lower extremities, (4) a history of a soft tissue injury of the lower extremity (eg, ankle, sprain) within 6 months of participation in the study, or (5) a reported pain greater than 0/10 while walking in bare feet. Potential participants were also excluded if they were currently receiving treatment for their lower extremity condition.
Instrumentation A 7-camera Vicon Motion Analysis System (Vicon, Oxford Metrics Group, Oxford, UK) and Vicon Nexus software were used to measure positions of retro-reflective markers
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Johanson et al attached to the lower limbs during stretching. Camera frequency was set at 100 Hz. An AMTI (Advance Medical Technology, Inc, Watertown, MA, USA) force plate recessed in the center of an elevated floor and integrated with the motion analysis system was used to measure ground reaction forces during stretching. The frequency of the force place was also set at 100 Hz. Vicon is considered a reliable system for the collection of kinematic data.18,34 Vicon’s standard lower extremity gait template (Plug-In Gait, Vicon, Oxford Metrics Group, Oxford, UK) in conjunction with the Oxford Foot Model template (Vicon, Oxford Metrics Group, Oxford, UK) and integrated with the force plate were used to analyze kinematic and kinetic variables during static stretching. The Oxford Foot Model is a reliable model for study of the foot and ankle5,7,23,34,36 and was used to differentiate dorsiflexion of the ankle and rearfoot from dorsiflexion at the midfoot and forefoot during static stretching.
Procedures Screening measurements. Except for eligibility criteria related to PROM and leg length, participants were initially screened by questionnaire via telephone, email, or face-toface interaction. If eligible on the basis of the initial screen, ankle dorsiflexion PROM with the knee extended and with the knee flexed was measured to further determine eligibility for the study as described below. All eligible participants who agreed to participate signed an informed consent form and rights of the participants were protected. Participants were randomly assigned to the order of side to be tested (involved/uninvolved for participants with unilateral involvement and right/left for participants with bilateral involvement) and dorsiflexion PROM measurement position (knee extended/flexed). The order of side and STJ position (pronation/supination) during motion analysis of participants’ stretching were also determined by random sequencing at this time. PROM of ankle dorsiflexion with the knee extended was measured with participants in prone and the foot off the end of the plinth.13 One investigator used a goniometer aligned to midlines drawn on the posterior calf and calcaneus to monitor the degree of varus/valgus at the STJ. This investigator maintained the STJ position in the anatomical zero position or at the end range of eversion PROM and also observed the knee joint to ensure an extended position. A second investigator aligned the stationary arm of a blinded goniometer with the fibular head and the moving arm over the fifth metatarsal. The investigator then applied passive force against the plantar aspect of the participant’s midfoot and forefoot in the direction of dorsiflexion. The first investigator read and documented the angle obtained. Passive dorsiflexion range of motion with the knee in a flexed position was measured in the same manner described
above, except the knee was flexed to 90 degrees. Ankle dorsiflexion PROM measurements were taken 3 times to assess intrarater reliability and the average of the 3 measurements was recorded. Ankle dorsiflexion PROM measurements were repeated by a second examiner on every third participant to assess interrater reliability. Leg length was assessed using a standard tape measure method measured with the participant in a supine position.29 Other measurements. STJ PROM, forefoot position and standing rearfoot angle were also measured. Forefoot position was measured in prone by aligning 1 arm of the goniometer parallel to the plane of the metatarsal heads, and the other arm perpendicular to the line on the posterior calcaneus mentioned previously, while keeping the STJ in neutral.29 To measure rearfoot angle, participants were asked to stand in a relaxed position while an investigator matched the lines of a goniometer to the midlines drawn on the posterior aspect of the calcaneus and calf.15 The Vicon system was calibrated using a wand calibration procedure.37 The Oxford Foot Model marker set was used in addition to Vicon’s standard lower extremity Plug-In Gait marker set (Figure 1). Reflective markers were applied to participants’ sacrum and bilaterally over the (1) Posterior Superior Iliac Spine (PSIS), (2) Anterior Superior Iliac spine (ASIS), (3) lateral thigh, (4) lateral aspect of the knee joint, (5) fibular head, (6) tibial tuberosity, (7) lateral calf, (8) anterior tibia, (9) lateral malleolus, (10) lateral calcaneus, (11) superior aspect of the posterior calcaneus, (12) midportion of the posterior calcaneus on a peg, (13) distal aspect of the posterior calcaneus, (14) proximal fifth metatarsal, (15) distal fifth metatarsal, (16) hallux, (17) distal aspect of the second metatarsal, (18) medial aspect of the distal first metatarsal, (19) dorsal aspect of the distal first metatarsal, (20) proximal first metatarsal, (21) medial malleolus, and (22) sustentaculum tali. Prior to the stretching trials, a static trial was collected. The participant stood on the force plate in relaxed standing for 5 seconds. Six foot markers, used only in the static trials, were removed prior to the stretching trials.34 A 15-degree wedge was constructed using three 5-degree beveled posting strips (Orthofeet Inc, Northvail, NJ, USA) affixed to one another. The posting strips were made of ethyl vinyl acetate with a manufacturer durometer A reading in the 50 to 60 range. The subject’s foot length was measured while standing with a standard tape measure to customize the length of each of the 3 wedges. The adhesive backings on the bottom of the wedges were removed, and they were aligned to create the desired 15-degree angle. The final wedge was affixed to a 56 cm × 35.5 cm poster board to create the template. Nonskid material was applied to the bottom of the template to allow for greater surface stability during stretching. The position of the template on the force plate was standardized by aligning the bottom of the
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Figure 2a. Participant stretching in supination using template on the left side.
Figure 1. Marker placement, anterior view.
template with the base of the force plate. This position was maintained by affixing the template on the floor with painter’s tape. The force plate was calibrated with the template in position before beginning data collection of the subjects’ stretching trials. In standing, participants were instructed to place the side to be stretched on the template with the 15-degree wedge over the force plate and perform a standard gastrocnemius stretching exercise (Figures 2a and 2b). Order of side and STJ position were determined by the previously established random sequence. The participants were instructed to align the medial side of their foot with the raised edge of the template when stretching in supination and to align the lateral side of their foot up with the raised edge of the template when stretching in pronation. Participants were then instructed to place their hands on an adjustable height walker for support in front of them, with 1 foot forward and 1 behind. The participants self-selected the position of the leading foot and leaned their trunk toward the walker, shifting their weight over the
Figure 2b. Posterior view of participant’s left foot stretching in pronation using template.
front foot, while straightening the knee of the back leg and maintaining contact of the heel of the back foot with the wedge (Figure 2a).9 During stretching the participants were instructed to feel slight discomfort to achieve an adequate stretch. The gastrocnemius stretching position was held for 30 seconds for 5 trials on each side in both pronation and supination in the randomly determined sequence for a total of 20 stretches. The parameters of the stretching exercises were based on previous investigator data regarding hamstring stretching exercises.2 Participants were allowed a 10-second rest period between stretches. Data processing. Marker trajectory gaps of 5 frames or less were interpolated using Woltrin Quintic spline. Marker paths were smoothed using a Woltering filter (Vicon, Oxford Metrics Group, Oxford, UK). Vicon software was then used to calculate segment angles and ground reaction
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Johanson et al Table 1. Participants’ Chronic Lower Extremity Injuries. Injury
Frequency
Anterior compartment syndrome Patellofemoral pain syndrome (PFPS) Plantar fasciitis Anterolateral shin splints Posteromedial shin splints Chronic ankle sprains Tibial stress fracture Involved Side Left Right Bilateral
1 2 6 7 5 4 2
Table 2. Participants’ Ankle Dorsiflexion Passive Range of Motion. Knee Position
Degrees (SD)
Knee extended Left Right Knee flexed Left Right
4.6 (2.9) 4.6 (4.1) 16.0 (5.7) 15.9 (6.4)
Frequency 6 10 11
Table 3. Joint Angles and Normalized Vertical Ground Reaction Force (GRF) During Stretching in Pronation and Supination. Variable
forces (Plug-In Gait and Oxford Foot Model, Vicon, Oxford Metrics Group, Oxford, UK). Using manual start and stop times for collection of the data during the stretching trials resulted in collection of slightly over 30 seconds of data (slightly more than 3000 frames). To consistently examine data across the different trials, the middle 3000 frames were analyzed, corresponding to the middle 30 seconds of the stretching trials. Means were calculated across the 30 seconds (3000 frames) for the following sagittal plane segment angles: (1) tibia to femur, (2) ankle/rearfoot to tibia, and (3) midfoot/forefoot to ankle/rearfoot. The vertical ground reaction force was normalized to body mass and the average also calculated across the 30 seconds. Averages from 3 trials from each of the stretching positions were used in the statistical analyses. Statistical analysis. Intraclass correlation coefficients (ICCs) were used to assess intrarater and interrater reliability of ankle dorsiflexion PROM with knee extended and knee flexed. Descriptive statistics were calculated for subject characteristics and dependent variables using means and standard deviations for continuous variables, and using frequencies for categorical variables. Normality of distribution and homogeneity of variance of dependent variables were assessed with Shapiro–Wilk and Levene’s tests, respectively. Two-way repeated measures ANOVA were used to assess differences between stretching position (pronation and supination) and side (right and left) for each dependent variable.
Results Participants’ chronic lower extremity injuries and side(s) of injury are reported in Table 1. Participants’ ankle dorsiflexion PROM measurements are summarized in Table 2. Descriptive statistics (means and standard deviations) of dependent variables are reported in Table 3, and a comparison of dorsiflexion at the midfoot/forefoot and ankle/
Pronation a
Peak average vertical GRF Left Right Knee extension Left Right Ankle/rearfoot dorsiflexion Left Right Midfoot/forefoot dorsiflexion Left Right
49.79 (4.12) 49.71 (3.93) 4.09 (7.22) 6.72 (6.71) 32.39 (9.25) 31.00 (8.09) 0.21 (8.21) 3.16 (8.16)
Supination 51.13 (4.97) 50.31 (4.01) 1.72 (8.27) 4.48 (6.67) 32.55 (10.88) 34.85 (9.09) –3.56 (8.50) –0.40 (9.10)
Values are reported as means and standard deviations. a Normalized to body mass.
rearfoot for the 2 stretching position (pronation and supination) is shown in Figure 3. Intrarater and interrater ICC values for ankle dorsiflexion PROM with the knee flexed and extended ranged from .94 to .98 and from .85 to .98, respectively. Normality of distribution and homogeneity of variance of dependent variables were established with the Shapiro–Wilk test and Levene’s test, respectively. Two-way repeated measures ANOVA revealed a significant increase in midfoot/forefoot dorsiflexion when stretching in pronation than when stretching in supination, F(1, 26) = 51.648, P < .001. ANOVAs also demonstrated significant increases in normalized vertical ground reaction force when stretching in supination compared to pronation, F(1, 26) = 5.126, P = .032, and more extension of the knee when stretching in supination compared to pronation, F(1, 26) = 29.102, P < .001. With the numbers available, no significant main effect of order of side, ground reaction force, ankle/ rearfoot dorsiflexion, or midfoot/forefoot dorsiflexion could be detected (P > .05). With the numbers available, no significant main effect for position for ankle/rearfoot dorsiflexion (P > .05) or significant side by position interactions could be detected (P > .05).
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Midfoot/Forefoot Dorsiflexion (Degrees)
4
Le
Right
3 1.66
2 1 0 -1
-1.38 -2.13
-2 -3 -4 -4.97
-5 -6
Supinaon
Pronaon Stretching Posion
Figure 3. Midfoot/forefoot dorsiflexion stretching in pronation and supination (means and standard error).
Discussion Our finding of increased midfoot/forefoot dorsiflexion when stretching with the STJ positioned in pronation compared to supination is consistent with accepted biomechanical principles related to the foot and ankle. This, however, is the first experimental demonstration of the more theoretical biomechanical hypotheses. When the STJ supinates, motion at the midtarsal joint (MTJ) is restricted to supination.27 With the STJ and MTJ positioned in supination, the sagittal plane component of pronation (dorsiflexion) would be primarily confined to the talocrural joint. This is supported by our finding of less dorsiflexion at the midfoot/forefoot when participants stretched with the STJ in supination versus pronation. Conversely, when the STJ pronates, the MTJ joint is free to move into pronation as well.27 With the STJ and MTJ in pronation, these joints contribute to the sagittal plane component of pronation (dorsiflexion) as well as the talocrural joint. This is supported by our finding of increased midfoot/forefoot dorsiflexion when participants stretched with the STJ in pronation versus supination. We believe this is an important finding because, to our knowledge, this is the only study that has directly demonstrated increased motion at the midfoot when stretching in pronation. Clinicians may specifically choose to instruct a patient to stretch in supination or pronation, depending on whether motion at the midfoot would best be limited or facilitated for a particular individual. Though we found more dorsiflexion at the ankle/rearfoot when participants stretched in supination compared to pronation (Table 3), with the numbers available, no statistically significant difference could be detected. Our marker set did not allow us to differentiate dorsiflexion occurring at the STJ from dorsiflexion occurring at the talocrural joint. Thus, it is possible that the nonsignificant but increased dorsiflexion at
the ankle/rearfoot represented increased dorsiflexion at the talocrural joint and decreased dorsiflexion at the STJ. We believe biomechanical determinants also underlie our finding that maximum knee extension was significantly increased when participants stretched with the STJ in supination compared to pronation. Because the ankle mortise is so congruent, motion of the talus cannot be accommodated within the mortise and therefore, motion of the tibia is concomitant with STJ motion. The tibia externally rotates when the STJ supinates and conversely, internally rotates when the STJ pronates.27 However, at the knee joint, tibial external rotation is required for full knee extension; this tibial external rotation is commonly called the “screw home mechanism.”6,26 Since we instructed participants to maintain the knee in extension during the stretch, it is apparent that they could not maintain full extension when stretching with the STJ in pronation, because the tibial internal rotation that accompanies STJ pronation precluded the necessary tibial external rotation needed to achieve full knee extension. When stretching with the STJ in supination, the tibial external rotation that accompanies STJ supination facilitated the “screw-home mechanism” and participants were able to maintain the knee is greater extension. Another factor to consider when contrasting the findings at the knee and ankle/rearfoot is that because of the greater knee extension when stretching in supination, participants would be expected to have less ankle/rearfoot dorsiflexion due to passive insufficiency of the gastrocnemius. The ankle/rearfoot dorsiflexion was increased when participants stretched with a more extended knee in STJ supination, though with the numbers available, no significant difference could be detected. Participants’ vertical average ground reaction force was greater when stretching in supination than pronation, which may have contributed to the increase in ankle/rearfoot dorsiflexion (though not significant) when stretching in supination. Vertical ground reaction force would be expected to vary with the degree of dorsiflexion angle. However, with greater dorsiflexion, the vertical component would be expected to decrease, not increase. We did not quantify level of comfort during the stretching, so a difference in degree of comfort between the stretching positions could explain the vertical ground reaction force findings. If participants were less comfortable stretching in pronation, they might have exerted less force. The difference in ground reaction force is also interesting in light of findings at the midfoot/forefoot. Even though vertical ground reaction force was lower when stretching in pronation, participants exhibited more dorsiflexion at the midfoot/forefoot. Thus, increased midfoot motion when stretching in pronation is not likely attributable to increased force.
Limitations We did not quantify degree of discomfort during the 2 different stretching positions, so a difference in level of
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Johanson et al comfort could account for some of our study findings. We also did not control for foot type or injury type. Individuals with structural findings of pes planus, hypermobility syndrome, or pes cavus may not respond similarly when stretching in STJ supination versus pronation, and future research is needed to specifically study stretching positions among these specific populations. Similarly, patients with different chronic conditions of the lower extremity may not exhibit the same patterns when stretching with the STJ in different positions. Though we measured vertical ground reaction force, we did not control force exerted during the stretching. The majority of our sample was female, so it is possible that our study findings would have differed if more males were included in our sample. Finally, low power could account for the lack of statistically significant findings at the ankle/rearfoot between the stretching positions.
Conclusion Gastrocnemius stretching performed with the STJ positioned in pronation resulted in more dorsiflexion at the midfoot/forefoot than stretching with the STJ in supination but did not affect the amount of dorsiflexion occurring at the ankle/rearfoot. Stretching with the STJ in supination was also accompanied by greater extension at the knee and greater vertical ground reaction force. Clinicians may want to consider STJ position during gastrocnemius stretching to either facilitate or limit recruitment of dorsiflexion motion at the midfoot/forefoot. Acknowledgments We would like to thank Jeanne Charles, PT, PhD, MSW, for technical support and Trisha Kesar, PT, PhD, for editorial assistance.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the Physical Therapy Association of Georgia.
References 1. Amis J, Jennings L, Graham D, Graham CE. Painful heel syndrome: radiographic and treatment assessment. Foot Ankle. 1988;9:91-95. 2. Bandy WD, Irion JM, Briggler M. The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Phys Ther. 1997;77:1090-1096. 3. Bates P. Shin splints—a literature review. Br J Sports Med. 1985;19:132-137. 4. Bohannon RW, Tiberio D, Waters G. Motion measured from forefoot and hindfoot landmarks during passive ankle
dorsiflexion range of motion. J Orthop Sports Phys Ther. 1991;13:20-22. 5. Carson MC, Harrington ME, Thompson N, et al. Kinematic analysis of a multi-segment foot model for research and clinical applications: a repeatability analysis. J Biomech. 2001;34:1299-1307. 6. Caruntu DI, Hefzy MS. 3-D anatomically based dynamic modeling of the human knee to include tibio-femoral and patello-femoral joints. J Biomech Eng. 2004;126:44-53. 7. Curtis DJ, Bencke J, Stebbins JA, Stansfield B. Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait. Gait Posture. 2009;30:118-121. 8. Donatelli RA, Wooden MJ. Biomechanical orthotics. In: Donatelli RA, eds. The Biomechanics of the Foot and Ankle. Philadelphia, PA: F. A. Davis; 1996:255-279. 9. Dutton M. Orthopaedic Examination, Evaluation, and Intervention. New York, NY: McGraw-Hill; 2008. 10. Elftman H. The transverse tarsal joint and its control. Clin Orthop. 1960;16:41-44. 11. Fredericson M. Common injuries in runners. Diagnosis, rehabilitation and prevention. Sports Med. 1996;21:49-72. 12. Gersham S. A literature review of midtarsal joint function. Clin Podriatr Med Surg. 1988;5:385-391. 13. Johanson M, Baer J, Hovermale H, Phouthavong P. Subtalar joint position during gastrocnemius stretching and ankle dorsiflexion range of motion. J Athl Train. 2008;43:172-178. 14. Johanson MA, Cuda BJ, Koontz JE, et al. Effect of stretching on ankle and knee angles and gastrocnemius activity during the stance phase of gait. J Sport Rehabil. 2009;18:521-534. 15. Johanson MA, Greenfeld L, Hung C, et al. The relationship between forefoot and rearfoot static alignment in pain-free individuals with above-average forefoot varus angles. Foot Ankle Spec. 2010;3:112-116. 16. Johanson MA, Wooden M., Catlin PA, et al. Effects of gastrocnemius stretching on ankle dorsiflexion and time-to-heel-off during the stance phase of gait. Phys Ther Sport. 2006;7:93-100. 17. Jordan RP. Ankle dorsiflexion at the heel-off phase of gait. J Am Podiatry Assoc. 1979;69:40-46. 18. Kadaba MP, Ramakrishnan HK, Wootten ME, et al. Repeatability of kinematic, kinetic, and electromyographic data in normal adult gait. J Orthop Res. 1989;7:849-860. 19. Karas M, Hoy DJ. Compensatory midfoot dorsiflexion in the individual with heelcord tightness: implications for orthotic device designs. J Prosthet Orthot. 2002;14:82-93. 20. Kaufman KR, Brodine SK, Shaffer RA, et al. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med. 1999;27:585-593. 21. Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med. 1991;19:66-71. 22. Levangie PK, Norkin CC. Joint Structure & Function: A Comprehensive Analysis. Philadelphia, PA: F. A. Davis; 2011. 23. Levinger P, Murley GS, Barton CJ, et al. A comparison of foot kinematics in people with normal- and flat-arched feet using the Oxford foot model. Gait Posture. 2010;32:519-523. 24. Lilletvedt J, Kreighbaum E, Phillips RL. Analysis of selected alignment of the lower extremity related to the shin splint syndrome. J Am Podiatry Assoc. 1979;69:211-217.
Downloaded from fai.sagepub.com at TEXAS SOUTHERN UNIVERSITY on November 28, 2014
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25. Messier SP, Pittala KA. Etiologic factors associated with selected running injuries. Med Sci Sports Exerc. 1988;20:501-505. 26. Moglo KE, Shirazi-Adl A. Cruciate coupling and screw-home mechanism in passive knee joint during extension–flexion. J Biomech. 2005;38:1075-1083. 27. Mueller MJ. The ankle and foot complex. In: Levangie PK, Norkin CC, eds. Joint Structure & Function: A Comprehensive Analysis. Philadelphia, PA: F. A. Davis; 2005:437-477. 28. Murray MP, Kory RC, Clarkson BH, Sepic SB. Comparison of free and fast speed walking patterns of normal men. Am J Phys Med. 1966;45:8-23. 29. Palmer ML, Epler ME. Fundamentals of Musculoskeletal Assessment Techniques. Philadelphia, PA: Lippincott; 1998. 30. Pope R, Herbert R, Kirwan J. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Aust J Physiother. 1998;44:165-172. 31. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: a matched case-control study. J Bone Joint Surg Am. 2003;85-A:872-877. 32. Riemann BL, DeMont RG, Ryu K, Lephart SM. The effects of sex, joint angle, and the gastrocnemius muscle on
passive ankle joint complex stiffness. J Athl Train. 2001;36: 369-375. 33. Schepsis AA, Leach RE, Gorzyca J. Plantar fasciitis. Etiology, treatment, surgical results, and review of the literature. Clin Orthop Relat Res. 1991;(266):185-196. 34. Stebbins J, Harrington M, Thompson N, et al. Repeatability of a model for measuring multi-segment foot kinematics in children. Gait Posture. 2006;23:401-410. 35. Subotnick SI. Equinus deformity as it affects the forefoot. J Am Podiatry Assoc. 1971;61:423-427. 36. Theologis TN, Harrington ME, Thompson N, Benson MK. Dynamic foot movement in children treated for congenital talipes equinovarus. J Bone Joint Surg Br. 2003;85:572-577. 37. Vicon Motion System. The Vicon Manual. Lake Forest, CA: Vicon Motion System; 2002. 38. Wilder RP, Sethi S. Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints. Clin Sports Med. 2004;23:55-81, vi. 39. Worrell TW, McCullough M, Pfeiffer A. Effect of foot position on gastrocnemius/soleus stretching in subjects with normal flexibility. J Orthop Sports Phys Ther. 1994;19:352-356.
Downloaded from fai.sagepub.com at TEXAS SOUTHERN UNIVERSITY on November 28, 2014
