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Plantar Fascia Coronal Length: A New Parameter for Plantar Fascia Assessment
The Journal of Foot & Ankle Surgery xxx (2015) 1–4
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Original Research
Plantar Fascia Coronal Length: A New Parameter for Plantar Fascia Assessment Ahmet Sinan Sari, MD 1, Emre Demircay, MD 2, Gokhan Cakmak, MD 3, M. Sukru Sahin, MD 3, I. Cengiz Tuncay, MD 4, Suleyman Altun, MD 5 1
Specialist, Department of Orthopaedic Surgery, Nigde State Hospital, Nigde, Turkey Assistant Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Istanbul Hospital, Altunizade, Istanbul, Turkey Assistant Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Alanya Hospital, Alanya, Antalya, Turkey 4 Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Ankara Hospital, Bahcelievler, Ankara, Turkey 5 Specialist, Department of Orthopaedic Surgery, Bakirkoy Dr Sadi Konuk Training Hospital, Bakirkoy, Istanbul, Turkey 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 3
The effects of gender and various anthropometric variables were previously reported as significant predictors of plantar fascia thickness. Although a strong correlation between either the body weight or body mass index (BMI) and plantar fascia thickness were not demonstrated, a moderate relation was stated. We retrospectively investigated the role of gender, height, weight, and body mass index on plantar fascia thickness at the calcaneal origin (PFCO) and 1 cm distal from the calcaneal origin (PF1cm) and the coronal length of the plantar fascia at the calcaneal origin (CLPF) in healthy subjects. The PFCO, PF1cm, and CLPF were retrospectively measured from magnetic resonance images of 100 healthy subjects. The gender, height, weight, and body mass index of the participants were also noted. Gender was a predictive factor for the length of the CLPF. The subjects with a BMI >25 kg/m2 had a significantly greater PFCO, PF1cm, and CLPF. Height was mildly and BMI and weight were moderately related to the PFCO. However the CLPF showed a better correlation with height, BMI, and weight than that of plantar fascia thickness. CLPF better reflected the role of weight, BMI, and height than its thickness. It is a new parameter that could be valuable in the evaluation of plantar fascia disorders. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: body mass index calcaneus magnetic resonance image plantar fasciosis subcalcanean spur weight
The plantar fascia is composed of longitudinally arranged collagen fibers that originate from the medial tubercle of the calcaneus. It stretches from the calcaneus to the distal aspect of the metatarsophalangeal joints, where it divides into 5 slips, 1 slip for each toe. The slips pass distal to the metatarsophalangeal joints, attaching to the plantar plates (1–3). The plantar fascia helps to maintain the medial longitudinal arch and transmit forces from the hind foot to the forefoot (4). Plantar fasciitis, a degenerative localized inflammatory disease of the plantar fascia is the most common cause of heel pain (5–8). Although the word fasciitis implies inflammation, research has indicated a noninflammatory, degenerative process within the fascia, suggesting the use of a more accurate term, plantar fasciosis (9). The diagnosis is typically determined from the history and the finding of localized tenderness along the inferomedial aspect of the calcaneal
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Ahmet Sinan Sari, MD, Department of Orthopaedic Surgery, Nigde State Hospital, Nigde, Turkey. E-mail address: [email protected] (A.S. Sari).
tuberosity (7,10). Diagnostic imagining has been used to investigate the involvement of specific anatomic structures in chronic heel pain. Thickening of the plantar fascia has become a well-established criterion for the diagnosis of plantar fasciitis. Several studies have assessed plantar fascia thickness using ultrasound in patients with plantar fasciitis (2,11–13). It has generally been accepted that a plantar fascia thickness of >4 mm with associated inflammatory changes would be consistent with plantar fasciitis (2,12,13). The ankle and foot biomechanics are designed to absorb and direct the forces during load bearing (14). Continuous overloading of the plantar fascia can produce increased plantar fascia thickness in healthy individuals. Several investigators have reported on healthy subjects with a plantar fascia thickness >4 mm in their control groups (11,15–20). The role of body weight, body mass index (BMI), height, athletic activity, and gender on plantar fascia thickness were investigated in previous research, with inconsistent results except for the role of body weight and BMI. Body weight and BMI were reported as significant predictor factors of plantar fascia thickness (2,13,20). Although a strong correlation between either the body weight or BMI and plantar fascia thickness could not be demonstrated, a moderate relation was stated (2,13,20).
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.11.002
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A.S. Sari et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–4
(MRI) in healthy subjects and investigated their relationship to gender, height, weight, and BMI. Patients and Methods
Fig. 1. Plantar fascia degeneration and calcaneal spur. The blue arrow indicates degeneration in the plantar fascia and the black arrow, a subcalcaneal spur (T1-weighted sequence).
Plantar fascia imagining in published studies has focused on only 1 dimension (sagittal thickness) of a 3-dimensional structure. Stress has been defined as the average force per unit area; thus, although the thickness of a structure can reflect its strain level to a degree, the cross-sectional area will be more accurate. The calcaneal origin of the plantar fascia is irregular and uneven. It is technically challenging to calculate the area of its insertion; however, consideration of 1 more dimension (coronal length), in addition to the sagittal thickness, might indicate the strain level better. We propose that the thickness of the plantar fascia reflects only 1 dimension of its weightbearing properties. The coronal length of the plantar fascia at the calcaneal origin (CLPF) should be another contributing factor. However, to the best our knowledge, CLPF has never been investigated in relation to anthropometric measures, such as weight, height, and BMI. We retrospectively measured the plantar fascia thickness at the calcaneal origin (PFCO) and 1 cm distal from calcaneal origin (PF1cm) and CLPF using magnetic resonance imaging
We reviewed all ankle MRI scans of the patients from the digital archive of our hospital from July 1, 2012 to June 10, 2013 to obtain 100 eligible ankle MRI scans as indicated by the statistical preanalysis. The patients were contacted for additional evaluation. Those who were studied further were excluded from the study if they had any of the following criteria: pain on the heel at or before data collection; a previous diagnosis and/or treatment of plantar fasciitis; diabetes, congestive heart failure, chronic renal disease, or any other chronic disease; connective tissue and lysosomal storage disorders; previous diagnosis of degenerative arthritis of ankle and foot or findings of degenerative arthritis of the ankle and foot on MRI; previous foot surgery; age <18 years or >65 years; and an obvious subcalcaneal spur or plantar fascia degeneration on MRI (Fig. 1). A total of 100 patients with an ankle MRI scan that satisfied these criteria were selected for our study group. All study participants provided informed consent, and the institutional review board approved the study. The age, gender, weight, height, and BMI of all 10 subjects were recorded. The ankle MRI scans of the patients were obtained from the hospital’s digital archive. The sagittal PFCO and PF1cm and CLPF was measured on the MRI (Magnetom Avanto 1.5 T, Siemens, Munich, Germany) scans. Fat-suppressed, T2-weighted sequences were used for the coronal plane measurements and T1-weighted sequences for the sagittal plane measurements. In both sequences, the slice thickness was 3 mm. The PFCO and PF1cm were measured on the sagittal plane images and CLPF on the coronal plane images (Figs. 2 and 3). The study groups were formed according to gender and BMI (<25 kg/m2 and >25 kg/m2). The subjects were evaluated for gender (41 males, 59 females), age, height, weight, and BMI (Table 1). In the second stage of the study, correlation analyses were performed between all the subjects’ height, weight, and BMI and the PFCO, PF1cm, and CLPF. Correlation analyses were performed on all the subjects’ parameters instead of by study group. Statistical Analysis Homogeneity (Levene’s test) and normality tests (Shapiro-Wilk test) were used to decide which statistical methods to apply in the comparison of the study groups. Pearson’s correlation coefficient and Spearman’s rho correlation coefficient were used to evaluate the variables. Covariance analysis was used to investigate the difference between 2 variables after removing the effects of the remaining variables. All statistical analyses were performed with the Statistical Package for Social Sciences, version 17.0 (SPSS, Chicago, IL). A p value < .05 was considered statistically significant.
Fig. 2. The plantar fascia on a magnetic resonance imaging scan. The origin of the plantar fascia on the sagittal and coronal plane images was used to measure the plantar fascia thickness at the calcaneal origin, plantar fascia thickness 1 cm distal to the calcaneal origin, and coronal length of plantar fascia at the calcaneal origin (arrows) (T1- and fat-suppressed T2-weighted sequences). The green line indicates the coronal plane crossing line on the sagittal plane image.
A.S. Sari et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–4
3
Fig. 3. Plantar fascia measures for a 31-year-old female subject (height 160 cm, weight 50 kg). The plantar fascia thickness at the calcaneal origin and plantar fascia thickness 1 cm distal to the calcaneal origin was 3 and 2 mm, respectively, and the coronal length of plantar fascia at the calcaneal origin was 24 mm.
correlation with the PFCO and PF1cm (r ¼ 0.491 and r ¼ 0.298, respectively) and a good correlation with the CLPF (r ¼ 0.554; Table 3).
Results The mean PFCO thickness was 4.08 1.02 (range 2 to 7, 95% confidence interval, 3.88 to 4.28, interquartile range 2) mm. Of the 100 patients, 31 (31%) had a PFCO of >4 mm. The mean PF1cm was 2.19 0.75 (range 1 to 5, 95% confidence interval 2.04 to 2.34, interquartile range 1) mm. The mean CLPF was 33.16 4.65 (range 20 to 50, 95% confidence interval 32.24 to 34.08, interquartile range 6) mm (Table 2). The age, height, weight, and BMI were not matched between the study groups; thus, the effect of gender on the PFCO, PF1cm, and CLPF was evaluated using covariance analyses to eliminate the possible influences of these parameters. Age had no significant effect on the PFCO, PF1cm, or CLPF (r ¼ 0.006, r ¼ 0.041, r ¼ 0.114, respectively). The PFCO and PF1cm did not show a significant relationship with gender when height, weight, and BMI were included in a multivariable model; however, gender was a predictive factor of CLPF, with the CLPF longer in males (Table 2). Height had an insignificant effect on the PFCO and PF1cm (r ¼ 0.216 and r ¼ 0.093, respectively) but a moderate effect on the CLPF (r ¼ 0.473; Table 3). Weight had a good correlation with the PFCO and CLPF (r ¼ 0.519 and r ¼ 0.681, respectively) and a moderate correlation with the PF1cm (r ¼ 0.297; Table 3). The BMI had a moderate Table 1 Anthropometric measures of study groups Group Sex Male (n ¼ 41) Female (n ¼ 59) BMI (kg/m2) <25 (n ¼ 54) >25 (n ¼ 46)
Age (y)
Weight (kg)
Height (cm)
BMI (kg/m2)
34.61 13.64 38 13.35
83.1 12.85 63.71 14.56
176.66 6.94 163.29 6.59
26.67 4.18 23.92 5.34
31.33 10.83 42.8 13.56
61.04 10.66 84.13 13.67
168.26 8.04 169.37 10.68
21.42 2.4 29.3 3.85
Abbreviation: BMI, body mass index. Data presented as mean standard deviation. The study groups were formed according to gender and BMI.
Discussion Determination of the plantar fascia thickness has gained popularity in the diagnosis of plantar fasciitis in the past decade. Wall et al (11) reported that a plantar fascia thickness of >4 mm and associated with inflammatory changes would be consistent with plantar fasciitis. Although large differences in the mean measured plantar fascia thickness have been reported by studies, a plantar fascia thickness of <4 mm has generally been considered normal (1,2,11,15). However, a plantar fascia thickness of >4 mm was frequently reported in the control groups or asymptomatic subjects in several reports (11,15–21). In our study, 31 of 100 subjects (31%) had a PFCO of >4 mm. This emphasizes, without inflammatory changes, that a PFCO thickness of >4 mm does not necessarily indicate pathologic features. Table 2 Mean CLPF, PFCO, PF1cm, and p values in study groups Group Sex Male (n ¼ 41) Female (n ¼ 59) p Value BMI (kg/m2) <25 (n ¼ 54) >25 (n ¼ 46) p Value Overall
CLPF (mm)
PFCO (mm)
PF1cm (mm)
36.17 3.91 31.09 3.95 < .05
4.39 0.94 3.86 1.02 .88
2.26 0.77 2.13 0.73 .45
31.26 3.98 35.39 4.32 < .05 33.16 4.65
3.70 0.86 4.52 1.02 < .05 4.08 1.02
1.98 0.65 2.43 0.77 < .05 2.19 0.74
Abbreviations: BMI, body mass index; CLPF, coronal length of the plantar fascia at the calcaneal origin; PFCO, plantar fascia thickness at the calcaneal origin; PF1cm, plantar fascia thickness 1 cm distal from the calcaneal origin. Data presented as mean standard deviation. CLPF, PFCO, and PF1cm were significantly greater in subjects with a BMI >25 kg/m2. Although the CLPF, PFCO, and PF1cm were all greater in males, only the difference in the CLPF was statistically significant.
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A.S. Sari et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–4
Table 3 Correlation coefficients between weight, height, and BMI and CLPF, PFCO, and PF1cm
Height Weight BMI
CLPF
PFCO
PF1cm
0.473* 0.681* 0.554*
0.216y,z 0.519* 0.491*
0.093z 0.297* 0.298*
Abbreviations: BMI, body mass index; CLPF, coronal length of the plantar fascia at the calcaneal origin; PFCO, plantar fascia thickness at the calcaneal origin; PF1cm, plantar fascia thickness 1 cm distal from the calcaneal origin. The CLPF showed more correlation with height, weight, and BMI than did the PFCO and PF1cm. * p < .01. y p < .05. z Pearson’s coefficients. All others are Spearman’s coefficients.
It is difficult to establish a reference value for plantar fascia thickness because of the variables among individuals and the lack of standardization of the measurement points. To establish the range of plantar fascia thickness in healthy individuals, the factors affecting it should be comprehended. Several variables, such as age, gender, height, weight, and BMI, were investigated for their effect on plantar fascia thickness. Conflicting findings have been reported on gender as an independent predictor of plantar fascia thickness. Wall et al (11) and Ozdemir et al (13) reported no significant differences in the mean plantar fascia thickness (measured 5 mm distal to the origin) between males and females. However, Uzel et al (20) and Pascual Huerta et al (2) found that the plantar fascia was significantly thicker in males. Uzel et al (20) measured the plantar fascia thickness at the distal border of the origin and 5 mm distal to this point, and Pascual Huerta et al (2) measured it 1 cm proximal from its origin. In our study, gender had no significant effect on the PFCO and PF1cm; however, the CLPF was significantly longer in males when the height, weight, and BMI were included in a multivariable model (p < .05). Although the height, weight, and BMI are directly related by definition, their effect on plantar fascia morphology is not the same. Several investigators reported moderate correlations between the plantar fascia thickness and the subject’s height (20), weight (2,20), and BMI (13,15,20). Pascual Huerta et al (2) found that the PFCO and PF1cm correlated moderately with the weight and that weight was the only predictive factor that affected the plantar fascia thickness at these locations. In our study, the thickness of the PF1cm was the least affected parameter by the variables such as height (r ¼ 0.093), weight (r ¼ 0.297), and BMI (r ¼ 0.298). CLPF was better at reflecting the effects of height, weight, and BMI (r ¼ 0.473; r ¼ 0.681; r ¼ 0.554, respectively). We found that the CLPF was also significantly longer in males (p < .05). Although the height, weight, and BMI are closely interrelated by definition, the weight had the best correlation with the CLPF and with the sagittal PFCO. The weight and BMI had about the same degree of correlation with the sagittal PF1cm (r ¼ 0.297 and r ¼ 0.298, respectively). The high correlation between the CLPF and patient weight imply that as the weight or BMI increases, the plantar fascia accommodates to the new conditions primarily by increasing its length in the coronal plane at the calcaneal origin and, secondarily, its thickness in the sagittal plane. We have not evaluated the CLPF in pathologic conditions. We designed the present study as a preliminary study. Investigation of CLPF in pathologic conditions will further establish its significance. Also, the measurements in the present study were taken from standard MRI scans. Although the plantar fascia could be distinctly demonstrated on standard MRI scans, owing to the irregular origin of the plantar fascia, we would prefer to have thinner slice MRI scans to obtain more accurate measurements.
Lemont et al (9) reported that a noninflammatory degenerative process is present within the fascia with plantar fasciitis and suggested the use of the term fasciosis instead of the term fasciitis. The results of our study and previous research suggest that a sagittal thickness of the plantar fascia >4 mm can be seen in healthy or control subjects (11,15–20). These findings limit the value of evaluating the plantar fascia at its sagittal thickness. An additional parameter for the evaluation of the plantar fascia might improve the understanding of its physiologic and pathologic states. To the best of our knowledge, the CLPF has never been studied. The measurement of the CLPF is as simple as measuring the plantar fascia thickness. Our study revealed that the CLPF better reflects the effects of variables such as the height, weight, and BMI than does the plantar fascia thickness. It is a new parameter that could be valuable in the evaluation of plantar fascia disorders. It should be investigated further in pathologic conditions to determine its significance.
Acknowledgments We thank Canan Yazıcı, MD, and Agah Tekindal, MD, Department of Biostatistics, for their efforts with the statistical analyses and Engin Baylar, MD, Department of Orthopedics, for his help in acquiring the patient data.
References 1. Healey K, Chen K. Plantar fasciitis: current diagnostic modalities and treatments. Clin Podiatr Med Surg 27:369–380, 2010. n Garcıa JM. Effect of gender, age and anthropometric 2. Pascual Huerta J, Alarco variables on plantar fascia thickness at different locations in asymptomatic subjects. Eur J Radiol 62:449–453, 2007. 3. Benjamin M. The fascia of the limbs and backda review. J Anat 214:1–18, 2009. 4. Erdemir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA. Dynamic loading of the plantar aponeurosis in walking. J Bone Joint Surg Am 86-A:546–552, 2004. 5. Singh D, Angel J, Bentley G, Trevino SG. Fortnightly review: plantar fasciitis. BMJ 315:172–175, 1997. 6. Rosenbaum AJ, DiPreta JA, Misener D. Plantar heel pain. Med Clin North Am 98:339–352, 2014. 7. Cutts S, Obi N, Pasapula C, Chan W. Plantar fasciitis. Ann R Coll Surg Engl 94: 539–542, 2012. 8. McMillan AM, Landorf KB, Barrett JT, Menz HB, Bird AR. Diagnostic imaging for chronic plantar heel pain: a systematic review and meta-analysis. J Foot Ankle Res 2:32, 2009. 9. Lemont H, Ammirati KM, Usen N. Plantar fasciitis: a degenerative process (fasciosis) without inflammation. J Am Podiatr Med Assoc 93:234–237, 2003. 10. Goff JD, Crawford R. Diagnosis and treatment of plantar fasciitis. Am Fam Physician 84:676–682, 2011. 11. Wall JR, Harkness MA, Crawford A. Ultrasound of plantar fasciitis. Foot Ankle Int 14:465–470, 1993. 12. Karabay N, Toros T, Hurel C. Ultrasonographic evaluation in plantar fasciitis. J Foot Ankle Surg 46:442–446, 2007. 13. Ozdemir H, Yilmaz E, Murat A, Karakurt L, Poyraz AK, Ogur E. Sonographic evaluation of plantar fasciitis and relation to body mass index. Eur J Radiol 54:443–447, 2005. 14. Karr SD. Subcalcaneal heel pain. Orthop Clin North Am 25:161–175, 1994. 15. Fabrikant JM, Park TS. Plantar fasciitis (fasciosis) treatment outcome study: plantar fascia thickness measured by ultrasound and correlated with patient self-reported improvement. Foot (Edinb) 21:79–83, 2011. 16. Wearing SC, Smeathers JE, Sullivan PM, Yates B, Urry SR, Dubois P. Plantar fasciitis: are pain and fascial thickness associated with arch shape and loading? Phys Ther 87:1002–1008, 2007. 17. Walther M, Radke S, Kirschner S, Ettl V, Gohlke F. Power Doppler findings in plantar fasciitis. Ultrasound Med Biol 30:435–440, 2004. 18. Williams PL, Smibert JG, Cox R, Mitchell R, Klenerman L. Imaging study of the painful heel syndrome. Foot Ankle 7:345–349, 1987. € nes T. Ultrasonographic appearance of the plantar fasciitis. Clin 19. Akfirat M, Sen C, Gu Imaging 27:353–357, 2003. uz A. The influence of athletic activity on 20. Uzel M, Cetinus E, Ekerbicer HC, Karaog the plantar fascia in healthy young adults. J Clin Ultrasound 34:17–21, 2006. 21. Gibbon WW, Long G. Ultrasound of the plantar aponeurosis (fascia). Skeletal Radiol 28:21–26, 1999.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Original Research
Plantar Fascia Coronal Length: A New Parameter for Plantar Fascia Assessment Ahmet Sinan Sari, MD 1, Emre Demircay, MD 2, Gokhan Cakmak, MD 3, M. Sukru Sahin, MD 3, I. Cengiz Tuncay, MD 4, Suleyman Altun, MD 5 1
Specialist, Department of Orthopaedic Surgery, Nigde State Hospital, Nigde, Turkey Assistant Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Istanbul Hospital, Altunizade, Istanbul, Turkey Assistant Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Alanya Hospital, Alanya, Antalya, Turkey 4 Professor, Department of Orthopaedic Surgery, Baskent University Medical Faculty Ankara Hospital, Bahcelievler, Ankara, Turkey 5 Specialist, Department of Orthopaedic Surgery, Bakirkoy Dr Sadi Konuk Training Hospital, Bakirkoy, Istanbul, Turkey 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 3
The effects of gender and various anthropometric variables were previously reported as significant predictors of plantar fascia thickness. Although a strong correlation between either the body weight or body mass index (BMI) and plantar fascia thickness were not demonstrated, a moderate relation was stated. We retrospectively investigated the role of gender, height, weight, and body mass index on plantar fascia thickness at the calcaneal origin (PFCO) and 1 cm distal from the calcaneal origin (PF1cm) and the coronal length of the plantar fascia at the calcaneal origin (CLPF) in healthy subjects. The PFCO, PF1cm, and CLPF were retrospectively measured from magnetic resonance images of 100 healthy subjects. The gender, height, weight, and body mass index of the participants were also noted. Gender was a predictive factor for the length of the CLPF. The subjects with a BMI >25 kg/m2 had a significantly greater PFCO, PF1cm, and CLPF. Height was mildly and BMI and weight were moderately related to the PFCO. However the CLPF showed a better correlation with height, BMI, and weight than that of plantar fascia thickness. CLPF better reflected the role of weight, BMI, and height than its thickness. It is a new parameter that could be valuable in the evaluation of plantar fascia disorders. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: body mass index calcaneus magnetic resonance image plantar fasciosis subcalcanean spur weight
The plantar fascia is composed of longitudinally arranged collagen fibers that originate from the medial tubercle of the calcaneus. It stretches from the calcaneus to the distal aspect of the metatarsophalangeal joints, where it divides into 5 slips, 1 slip for each toe. The slips pass distal to the metatarsophalangeal joints, attaching to the plantar plates (1–3). The plantar fascia helps to maintain the medial longitudinal arch and transmit forces from the hind foot to the forefoot (4). Plantar fasciitis, a degenerative localized inflammatory disease of the plantar fascia is the most common cause of heel pain (5–8). Although the word fasciitis implies inflammation, research has indicated a noninflammatory, degenerative process within the fascia, suggesting the use of a more accurate term, plantar fasciosis (9). The diagnosis is typically determined from the history and the finding of localized tenderness along the inferomedial aspect of the calcaneal
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Ahmet Sinan Sari, MD, Department of Orthopaedic Surgery, Nigde State Hospital, Nigde, Turkey. E-mail address: [email protected] (A.S. Sari).
tuberosity (7,10). Diagnostic imagining has been used to investigate the involvement of specific anatomic structures in chronic heel pain. Thickening of the plantar fascia has become a well-established criterion for the diagnosis of plantar fasciitis. Several studies have assessed plantar fascia thickness using ultrasound in patients with plantar fasciitis (2,11–13). It has generally been accepted that a plantar fascia thickness of >4 mm with associated inflammatory changes would be consistent with plantar fasciitis (2,12,13). The ankle and foot biomechanics are designed to absorb and direct the forces during load bearing (14). Continuous overloading of the plantar fascia can produce increased plantar fascia thickness in healthy individuals. Several investigators have reported on healthy subjects with a plantar fascia thickness >4 mm in their control groups (11,15–20). The role of body weight, body mass index (BMI), height, athletic activity, and gender on plantar fascia thickness were investigated in previous research, with inconsistent results except for the role of body weight and BMI. Body weight and BMI were reported as significant predictor factors of plantar fascia thickness (2,13,20). Although a strong correlation between either the body weight or BMI and plantar fascia thickness could not be demonstrated, a moderate relation was stated (2,13,20).
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.11.002
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A.S. Sari et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–4
(MRI) in healthy subjects and investigated their relationship to gender, height, weight, and BMI. Patients and Methods
Fig. 1. Plantar fascia degeneration and calcaneal spur. The blue arrow indicates degeneration in the plantar fascia and the black arrow, a subcalcaneal spur (T1-weighted sequence).
Plantar fascia imagining in published studies has focused on only 1 dimension (sagittal thickness) of a 3-dimensional structure. Stress has been defined as the average force per unit area; thus, although the thickness of a structure can reflect its strain level to a degree, the cross-sectional area will be more accurate. The calcaneal origin of the plantar fascia is irregular and uneven. It is technically challenging to calculate the area of its insertion; however, consideration of 1 more dimension (coronal length), in addition to the sagittal thickness, might indicate the strain level better. We propose that the thickness of the plantar fascia reflects only 1 dimension of its weightbearing properties. The coronal length of the plantar fascia at the calcaneal origin (CLPF) should be another contributing factor. However, to the best our knowledge, CLPF has never been investigated in relation to anthropometric measures, such as weight, height, and BMI. We retrospectively measured the plantar fascia thickness at the calcaneal origin (PFCO) and 1 cm distal from calcaneal origin (PF1cm) and CLPF using magnetic resonance imaging
We reviewed all ankle MRI scans of the patients from the digital archive of our hospital from July 1, 2012 to June 10, 2013 to obtain 100 eligible ankle MRI scans as indicated by the statistical preanalysis. The patients were contacted for additional evaluation. Those who were studied further were excluded from the study if they had any of the following criteria: pain on the heel at or before data collection; a previous diagnosis and/or treatment of plantar fasciitis; diabetes, congestive heart failure, chronic renal disease, or any other chronic disease; connective tissue and lysosomal storage disorders; previous diagnosis of degenerative arthritis of ankle and foot or findings of degenerative arthritis of the ankle and foot on MRI; previous foot surgery; age <18 years or >65 years; and an obvious subcalcaneal spur or plantar fascia degeneration on MRI (Fig. 1). A total of 100 patients with an ankle MRI scan that satisfied these criteria were selected for our study group. All study participants provided informed consent, and the institutional review board approved the study. The age, gender, weight, height, and BMI of all 10 subjects were recorded. The ankle MRI scans of the patients were obtained from the hospital’s digital archive. The sagittal PFCO and PF1cm and CLPF was measured on the MRI (Magnetom Avanto 1.5 T, Siemens, Munich, Germany) scans. Fat-suppressed, T2-weighted sequences were used for the coronal plane measurements and T1-weighted sequences for the sagittal plane measurements. In both sequences, the slice thickness was 3 mm. The PFCO and PF1cm were measured on the sagittal plane images and CLPF on the coronal plane images (Figs. 2 and 3). The study groups were formed according to gender and BMI (<25 kg/m2 and >25 kg/m2). The subjects were evaluated for gender (41 males, 59 females), age, height, weight, and BMI (Table 1). In the second stage of the study, correlation analyses were performed between all the subjects’ height, weight, and BMI and the PFCO, PF1cm, and CLPF. Correlation analyses were performed on all the subjects’ parameters instead of by study group. Statistical Analysis Homogeneity (Levene’s test) and normality tests (Shapiro-Wilk test) were used to decide which statistical methods to apply in the comparison of the study groups. Pearson’s correlation coefficient and Spearman’s rho correlation coefficient were used to evaluate the variables. Covariance analysis was used to investigate the difference between 2 variables after removing the effects of the remaining variables. All statistical analyses were performed with the Statistical Package for Social Sciences, version 17.0 (SPSS, Chicago, IL). A p value < .05 was considered statistically significant.
Fig. 2. The plantar fascia on a magnetic resonance imaging scan. The origin of the plantar fascia on the sagittal and coronal plane images was used to measure the plantar fascia thickness at the calcaneal origin, plantar fascia thickness 1 cm distal to the calcaneal origin, and coronal length of plantar fascia at the calcaneal origin (arrows) (T1- and fat-suppressed T2-weighted sequences). The green line indicates the coronal plane crossing line on the sagittal plane image.
A.S. Sari et al. / The Journal of Foot & Ankle Surgery xxx (2015) 1–4
3
Fig. 3. Plantar fascia measures for a 31-year-old female subject (height 160 cm, weight 50 kg). The plantar fascia thickness at the calcaneal origin and plantar fascia thickness 1 cm distal to the calcaneal origin was 3 and 2 mm, respectively, and the coronal length of plantar fascia at the calcaneal origin was 24 mm.
correlation with the PFCO and PF1cm (r ¼ 0.491 and r ¼ 0.298, respectively) and a good correlation with the CLPF (r ¼ 0.554; Table 3).
Results The mean PFCO thickness was 4.08 1.02 (range 2 to 7, 95% confidence interval, 3.88 to 4.28, interquartile range 2) mm. Of the 100 patients, 31 (31%) had a PFCO of >4 mm. The mean PF1cm was 2.19 0.75 (range 1 to 5, 95% confidence interval 2.04 to 2.34, interquartile range 1) mm. The mean CLPF was 33.16 4.65 (range 20 to 50, 95% confidence interval 32.24 to 34.08, interquartile range 6) mm (Table 2). The age, height, weight, and BMI were not matched between the study groups; thus, the effect of gender on the PFCO, PF1cm, and CLPF was evaluated using covariance analyses to eliminate the possible influences of these parameters. Age had no significant effect on the PFCO, PF1cm, or CLPF (r ¼ 0.006, r ¼ 0.041, r ¼ 0.114, respectively). The PFCO and PF1cm did not show a significant relationship with gender when height, weight, and BMI were included in a multivariable model; however, gender was a predictive factor of CLPF, with the CLPF longer in males (Table 2). Height had an insignificant effect on the PFCO and PF1cm (r ¼ 0.216 and r ¼ 0.093, respectively) but a moderate effect on the CLPF (r ¼ 0.473; Table 3). Weight had a good correlation with the PFCO and CLPF (r ¼ 0.519 and r ¼ 0.681, respectively) and a moderate correlation with the PF1cm (r ¼ 0.297; Table 3). The BMI had a moderate Table 1 Anthropometric measures of study groups Group Sex Male (n ¼ 41) Female (n ¼ 59) BMI (kg/m2) <25 (n ¼ 54) >25 (n ¼ 46)
Age (y)
Weight (kg)
Height (cm)
BMI (kg/m2)
34.61 13.64 38 13.35
83.1 12.85 63.71 14.56
176.66 6.94 163.29 6.59
26.67 4.18 23.92 5.34
31.33 10.83 42.8 13.56
61.04 10.66 84.13 13.67
168.26 8.04 169.37 10.68
21.42 2.4 29.3 3.85
Abbreviation: BMI, body mass index. Data presented as mean standard deviation. The study groups were formed according to gender and BMI.
Discussion Determination of the plantar fascia thickness has gained popularity in the diagnosis of plantar fasciitis in the past decade. Wall et al (11) reported that a plantar fascia thickness of >4 mm and associated with inflammatory changes would be consistent with plantar fasciitis. Although large differences in the mean measured plantar fascia thickness have been reported by studies, a plantar fascia thickness of <4 mm has generally been considered normal (1,2,11,15). However, a plantar fascia thickness of >4 mm was frequently reported in the control groups or asymptomatic subjects in several reports (11,15–21). In our study, 31 of 100 subjects (31%) had a PFCO of >4 mm. This emphasizes, without inflammatory changes, that a PFCO thickness of >4 mm does not necessarily indicate pathologic features. Table 2 Mean CLPF, PFCO, PF1cm, and p values in study groups Group Sex Male (n ¼ 41) Female (n ¼ 59) p Value BMI (kg/m2) <25 (n ¼ 54) >25 (n ¼ 46) p Value Overall
CLPF (mm)
PFCO (mm)
PF1cm (mm)
36.17 3.91 31.09 3.95 < .05
4.39 0.94 3.86 1.02 .88
2.26 0.77 2.13 0.73 .45
31.26 3.98 35.39 4.32 < .05 33.16 4.65
3.70 0.86 4.52 1.02 < .05 4.08 1.02
1.98 0.65 2.43 0.77 < .05 2.19 0.74
Abbreviations: BMI, body mass index; CLPF, coronal length of the plantar fascia at the calcaneal origin; PFCO, plantar fascia thickness at the calcaneal origin; PF1cm, plantar fascia thickness 1 cm distal from the calcaneal origin. Data presented as mean standard deviation. CLPF, PFCO, and PF1cm were significantly greater in subjects with a BMI >25 kg/m2. Although the CLPF, PFCO, and PF1cm were all greater in males, only the difference in the CLPF was statistically significant.
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Table 3 Correlation coefficients between weight, height, and BMI and CLPF, PFCO, and PF1cm
Height Weight BMI
CLPF
PFCO
PF1cm
0.473* 0.681* 0.554*
0.216y,z 0.519* 0.491*
0.093z 0.297* 0.298*
Abbreviations: BMI, body mass index; CLPF, coronal length of the plantar fascia at the calcaneal origin; PFCO, plantar fascia thickness at the calcaneal origin; PF1cm, plantar fascia thickness 1 cm distal from the calcaneal origin. The CLPF showed more correlation with height, weight, and BMI than did the PFCO and PF1cm. * p < .01. y p < .05. z Pearson’s coefficients. All others are Spearman’s coefficients.
It is difficult to establish a reference value for plantar fascia thickness because of the variables among individuals and the lack of standardization of the measurement points. To establish the range of plantar fascia thickness in healthy individuals, the factors affecting it should be comprehended. Several variables, such as age, gender, height, weight, and BMI, were investigated for their effect on plantar fascia thickness. Conflicting findings have been reported on gender as an independent predictor of plantar fascia thickness. Wall et al (11) and Ozdemir et al (13) reported no significant differences in the mean plantar fascia thickness (measured 5 mm distal to the origin) between males and females. However, Uzel et al (20) and Pascual Huerta et al (2) found that the plantar fascia was significantly thicker in males. Uzel et al (20) measured the plantar fascia thickness at the distal border of the origin and 5 mm distal to this point, and Pascual Huerta et al (2) measured it 1 cm proximal from its origin. In our study, gender had no significant effect on the PFCO and PF1cm; however, the CLPF was significantly longer in males when the height, weight, and BMI were included in a multivariable model (p < .05). Although the height, weight, and BMI are directly related by definition, their effect on plantar fascia morphology is not the same. Several investigators reported moderate correlations between the plantar fascia thickness and the subject’s height (20), weight (2,20), and BMI (13,15,20). Pascual Huerta et al (2) found that the PFCO and PF1cm correlated moderately with the weight and that weight was the only predictive factor that affected the plantar fascia thickness at these locations. In our study, the thickness of the PF1cm was the least affected parameter by the variables such as height (r ¼ 0.093), weight (r ¼ 0.297), and BMI (r ¼ 0.298). CLPF was better at reflecting the effects of height, weight, and BMI (r ¼ 0.473; r ¼ 0.681; r ¼ 0.554, respectively). We found that the CLPF was also significantly longer in males (p < .05). Although the height, weight, and BMI are closely interrelated by definition, the weight had the best correlation with the CLPF and with the sagittal PFCO. The weight and BMI had about the same degree of correlation with the sagittal PF1cm (r ¼ 0.297 and r ¼ 0.298, respectively). The high correlation between the CLPF and patient weight imply that as the weight or BMI increases, the plantar fascia accommodates to the new conditions primarily by increasing its length in the coronal plane at the calcaneal origin and, secondarily, its thickness in the sagittal plane. We have not evaluated the CLPF in pathologic conditions. We designed the present study as a preliminary study. Investigation of CLPF in pathologic conditions will further establish its significance. Also, the measurements in the present study were taken from standard MRI scans. Although the plantar fascia could be distinctly demonstrated on standard MRI scans, owing to the irregular origin of the plantar fascia, we would prefer to have thinner slice MRI scans to obtain more accurate measurements.
Lemont et al (9) reported that a noninflammatory degenerative process is present within the fascia with plantar fasciitis and suggested the use of the term fasciosis instead of the term fasciitis. The results of our study and previous research suggest that a sagittal thickness of the plantar fascia >4 mm can be seen in healthy or control subjects (11,15–20). These findings limit the value of evaluating the plantar fascia at its sagittal thickness. An additional parameter for the evaluation of the plantar fascia might improve the understanding of its physiologic and pathologic states. To the best of our knowledge, the CLPF has never been studied. The measurement of the CLPF is as simple as measuring the plantar fascia thickness. Our study revealed that the CLPF better reflects the effects of variables such as the height, weight, and BMI than does the plantar fascia thickness. It is a new parameter that could be valuable in the evaluation of plantar fascia disorders. It should be investigated further in pathologic conditions to determine its significance.
Acknowledgments We thank Canan Yazıcı, MD, and Agah Tekindal, MD, Department of Biostatistics, for their efforts with the statistical analyses and Engin Baylar, MD, Department of Orthopedics, for his help in acquiring the patient data.
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