ACTA LETTER TO THE EDITOR ORTHOPAEDICA et TRAUMATOLOGICA Acta Orthop Traumatol Turc 2011;45(4):288-290 TURCICA doi:10.3944/AOTT.2011.288 Response to: Evaluation of the medial longitudinal arch: a comparison between the dynamic plantar pressure measurement system and radiographic analysis Dear Editor, Studies have shown that assessments and measure- ments related to foot can change with loading and We have read the article “Evaluation of the medial lon- severity of loading and this variation is especially gitudinal arch: a comparison between the dynamic prominent in patients with foot problem.[2,3] In this con- plantar pressure measurement system and radiograph- text, measurement of some feet which are normal ic analysis” by Yalç›n et al.[1] with interest. We want to under static conditions may reveal pathological values congratulate the researches. However, we would like to under certain load. In the study, presence of patients share some questions related to this study with you. with radiologically normal but pathologic in pedobaro- The medial longitudinal arch varies with age as the metric measurements may cause problems in compar- authors indicated. Although the wide sampling age ison. From this perspective, normal pressure values in range (11-85 years) compatible with the universe of normal cases should be clearly stated and the measure- patients encountered in the daily practice is an advan- ments obtained should be classified accordingly. tage, this can be cause problems in “definition” and When the values obtained from the study from 0.04 to “interpretation” of an age-related parameter and affect 0.17 has been accepted as a reference value for normal the error rate of inferences. In this context, having subjects, the authors’ opinions on the reasons of this similar number of patients in predefined age ranges wide range will enlighten us. and making statistical evaluation accordingly will In the last paragraph the statements “the talo-first minimize error when interpreting the results. We con- metatarsal and talohorizontal angles also give helpful sider that such a sub-assessment analysis would be information on the height of the arch where a pedo- appropriate. Additionally, indicating standard devia- barograph is not available. The talo-first metatarsal tion in this parameter with wide range could also give and talohorizontal angles obtained statically may pre- an opinion to us. dict dynamic posture of the foot.” [1] are taken part. Mid- In the study, 95 patients who were found to have foot pressure measurement is written in the numerator normal feet based on radiographic examination were part of the formula that is used as an arch index. included in the study. Because results of radiological However, calcaneal pitch angle and talocalcaneal assessment have quite a wide range, we think that angle are used in the evaluation of the back foot as evaluation criteria for a “normal” foot should be clear- specified by the authors. We believe that it should be made clear whether or not there is a relationship ly stated. Additionally, because roentgenograms of between back foot pressure values or index measure- both right and left feet of the subjects were taken and ments which take it as a reference and static angular the sample size was doubled (95x2), the effect of dom- measurements evaluating the back foot should. Any inant foot on pressure values should also be investigat- conclusion derived from these data should be present- ed. Body weight or body-mass index is one of the ed in detail. In addition, statistically insignificant other factors that may affect the pressure, so we think inverse relationship (r; negative) between talocal- that also an evaluation could be done from this aspect. caneal and calcaneal pitch angles and arch index was Our other concerns related to the methodology of found in the evaluation of the correlation. In other the study is about how long the walking time is, when words, these two angles will decrease as index increas- the values are taken as a measurement and if the cur- es and vice versa. In this context, making inferences rent software program is ever used to evaluate or not without considering the relationship between the in a research like this or another similar topic. We measured angles themselves can lead to possible believe that informing on these issues would be useful. errors. We think that when the relationship between Letter to the Editor 289 talohorizontal, talo-first metatarsal angles in signifi- References cant correlation and talocalcaneal, calcaneal pitch 1. Yalç›n N, Esen E, Kanatl› U, Yetkin U. Evaluation of the angles in insignificant inverse correlation with arch medial longitudinal arch: a comparison between the dynam- index are assessed, comments and inferences may also ic plantar pressure measurement system and radiographic be different according to the obtaining significant or analysis. Acta Orthop Traumatol Turc 2010;44:241-5. insignificant results in pressure measurements. 2. fiahin N, Öztürk A, At›c› T. Foot mobility and plantar fas- cia elasticity in patients with plantar fasciitis. Acta Orthop Best regards, Traumatol Turc 2010;44:385-91. 3. Prichasuk S, Subhadrabandhu T. The relationship of pes Teoman ATICI planus and calcaneal spur to plantar heel pain. Clin Orthop Department of Orthopaedics and Traumatology, Relat Res 1994;(306):192-6. Faculty of Medicine, Uluda¤ University, Bursa, Turkey e-mail: teoman@uludag.edu.tr Nam›k fiAH‹N, Alpaslan ÖZTÜRK Department of Orthopaedics and Traumatology, fievket Y›lmaz Training and Research Hospital, Bursa, Turkey Authors' reply Dear Editor, mity detected clinically and without any radiological deformity on tarsal, metatarsal bones and phalanxes We would like to thank you having allowed us to altering the anatomical structure of the foot. answer this letter. We are glad that our article has cre- Because the comparison of the data of right and ated interest and has afforded the expressed thoughts left foot is not different between each other, only the on the authors of the letter. data of one side was used in the whole study in order This study was planned that there is lack of com- to prevent statistical confusion. parison studies with wide range of age in adult popu- It is known that weight and body mass index have lation although there are some in pediatric age groups. influence on foot pressures. However, in this study, As we know, arch shows variability in accordance arch index was calculated as the proportion of the area with bone development. After bone maturation, it of middle foot to the sum of the areas of the whole becomes constant in adulthood unless there occurs a foot (forefoot, midfoot, hindfoot, except phalanxes) secondary pathology. Thus, we did not subgroup the during stance phase, not with the plantar pressures of normal individuals according to age, thinking that the foot. Therefore, pressure values are out of scope of would not change our results significantly. Also the this study. main purpose of this study was to compare dynamic Pedobarographic data obtained from the study foot pressure parameters and static radiographic group was compared with the radiographic data parameters. The correlation of these two is not obtained during the same time. During evaluation, the dependent with age. According to us, for this reason, standardized tecnique of our laboratory was used. For evaluating the age with subgroups is not pertinent. standardization, all subjects walked on the walking The individuals enrolled to the study were the ones platform, having at least three steps for each foot applied to the pedobarography laboratory for different before stepping on the middle of a 7m platform. The reasons and neither any pathology nor deformity pressure pictures were saved only if the whole foot detected after both clinical and radiological examina- reflects on the platform, letting for the analysis. It tions. In addition, no mechanical disorders established would be better that we have mentioned this point in after pedobarographic analysis. In other words, nor- detail in the article. We would like to thank for the mal concept is defined as the feet without any defor- suggestion of the authors. For evaluation, the original 290 Acta Orthop Traumatol Turc softwares mentioned in the article were used. The and decrease of this area will inform us about the same softwares and the technique have been also used degree of medial arch height. In case of a decrease in in similar studies.[1,2] arch (pes planus), medial area increases and thus, index The defined normal values of arch index can also value increases. In pes cavus, it is just the opposite. be seen in wide range in the literature.[2,3] The reason The negative values of talocalcaneal and calcaneal might be the variability of normal foot anatomy in pitch angles might be confusing whether if there person to person and reflection of this variability to found a statistical difference with arch index. the results of pedobarographic analysis, same as the Increasing of calcaneal slope which is a parameter of measurement of radiographic analysis of angles both measurements, increases the height of arch. accordingly. Because an increase in arch height means a decrease Evaluating the arch index values of normal or in arch index, negative correlation would be expected. pathological feet was not the scope of this study. To As mentioned in the article, these two angles were not accentuate, area analysis, not pressures, were evaluat- found to be correlated significantly with arch index ed in this study. The individuals having severe struc- (p>0.05). tural abnormalities were not enrolled to the study. In Sincerely, addition, individuals only expressing difference on arch height were not removed. As in the article that Nadir YALÇIN the authors cited, there are some studies showing foot Department of Orthopaedics and Traumatology, plantar pressure changes in pathological subjects. Ankara Atatürk Training and Research Hospital, Ankara, Turkey However, there are other studies arguing just the e-mail: drmnyalcin@yahoo.com opposite.[4] Today, it is clear that plantar pressures Erdinç ESEN, Ulunay KANATLI, Haluk YETK‹N may be effected by variations and pathologies of a Department of Orthopaedics and Traumatology, kinematic chain starting from the back to the toes. Faculty of Medicine, Gazi University, Ankara, Turkey Because radiographic values and plantar areas were used as they are indicators of medial arch height, the References study was independent with pressure values. 1. Kanatl› U, Yetkin H, Cila E. Footprint and radiographic The four radiographic measurement method used analysis of the feet. J Pediatr Orthop 2001;21:225-8. and referred in the article are believed as they are giv- 2. Kanatl› U, Yetkin H, fiimflek A, Besli K, Özturk A. The ing information on medial longitudinal arch of foot and relationship between accessory navicular and medial lon- are being used rather frequently in general. In addition, gitudinal arch: evaluation with a plantar pressure distribu- the arch index used in the study is a method that tion measurement system. Foot Ankle Int 2003;24:486-9. informs about the medial longitudinal arch of foot 3. Cavanagh PR, Rodgers MM. The arch index: a usefulmeasure from footprints. J Biomech 1987;20:547-51. which can be determined both statically and dynami- 4. Kanatl› U, Yetkin H, fiimflek A, Besli K, Özturk A. The cally. The reason of writing the middlefoot area to the relationship of the heel pad compressibility and plantar numerator of the fraction is because of any increase pressure distribution. Foot Ankle Int 2001;22:662-5.