Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 Â± 1.2Âº. The Knee joint was shown to be medially inclined 3.6 Â± 1.7Âº in men comparing 2 Â± 2Âº of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 Â± 1.6Âº. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery

Jabalameli, M.

Moghimi, J.

Nojomi, M.

Yeganeh, A.

ACTA MEDICA IRANICA

English

eprints Iran University of Medical Sciences

 ORIGINAL ARTICLE   Corresponding Author: A. Yeganeh  Department of Orthopedic Surgery, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran  Tel: +98 912 2187996, Fax: +98 21 66517118, E-mail address: yeganeh471@yahoo.com  Parameters of Lower Extremities Alignment View in  Iranian Adult Population  Mahmoud Jabalameli1, Javad Moghimi2, Ali Yeganeh2, and Marzieh Nojomi3 1 Department of Orthopedic Surgery, Shafa Yahyaiyan Hospital, Iran University of Medical Sciences, Tehran, Iran 2 Department of Orthopedic Surgery, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran 3 Department of Community Medicine, School of Medicine, Iran University of Medical Sciences, Tehran, Iran  Received: 5 Oct. 2013; Accepted: 10 Jun. 2014  Abstract- Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 ± 1.2º. The Knee joint was shown to be medially inclined 3.6 ± 1.7º in men comparing 2 ± 2º of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 ± 1.6º. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery.  © 2015 Tehran University of Medical Sciences. All rights reserved.  Acta Medica Iranica, 2015;53(5):293-296.   Keywords: Adult; Ankle joint; Iran; Lower limb; Knee  Introduction  There is a delicate correlation exists between human anatomy and function. Adequate knowledge is necessary regarding the normal biomechanics of limbs and their variations. Achieving normal axial alignment of the lower limb cannot be overemphasized in reconstructive surgery of the knee, such as total knee arthroplasty and high tibial osteotomy (1). Primary reference values were documented by Moreland et al., and Hsu et al., based on the radiographic evaluation (2,3). Subsequently, studies were undertaken to modify the results based on age and sex. Ethnic differences gained more attention especially with the advent of newer designs of TKA prostheses (4-6). A few studies surveyed anatomic differences among Asian populations (7-9). We aimed to establish the lower-limb alignment norms in Iranian population and compare them with those reported from the western and some Asian countries.   Materials and methods  During autumn 2008, a total of 200 patients of hand clinic of Shafa Yahyaian Hospital (a referral orthopedic center in the capital of Iran) were volunteered to enter the survey. One hundred of them were selected randomly (half of each sex) aged 15- 32 years. Previous history of pain, any deformity or surgery of the lower extremity or trauma was the exclusion criteria for the participants. A full weight-bearing anteroposterior alignment view of the entire lower limbs was performed with bare foot, patellae facing forward and full extension of knees. X-ray beam was centered on the knee at a distance of 2.5 meters. Parameters of lower extremities alignment view  294    Acta Medica Iranica, Vol. 53, No. 5 (2015)   The alignment parameters were measured according to the methods described by Moreland with modifications applied by Tang in Chinese population study (2,8). First, following landmarks were determined: 1) The center of the femoral head via Mose circles,  2) Knee center as midpoint between the tips of the tibial spines or center of the tibia/ femoral condyles at the level of the subchondral bone of the medial tibial plateau/ lateral femoral condyle, and  3) Ankle center as a point midway between two malleoli or talus center at the level of the subchondral bone. Moreover, the transverse axis of the knee was drawn as a line tangential to the most distal points of the femoral condyles, and transverse axis of the ankle delineating subchondral plate of the distal part of the tibia. The femur and tibia mechanical axes were sketched with lines joining the center of the knee to the center of the femoral head and the center of the knee to the center of the ankle, respectively. Anatomical axes of femur were marked in two methods: one connecting femoral shaft center I (at the mid-shaft level) and another connecting femoral shaft center II (10 cm proximal to knee) to the knee center. We used the latter construct in this study as it represents femoral modularly canal more closely. Five angles were defined from the intersection of landmarks mentioned below (Figure 1).                     Figure 1. Five angles were defined from the intersection of landmarks mentioned (2)  A: The medial angle formed by the mechanical axes of the femur and the tibia. B: the Inferolateral angle formed by the transverse axis of the knee and the mechanical axis of the tibia that represents knee joint inclination. C: Angle between mechanical and anatomical II axes of the femur. D: Lateral angle formed by the mechanical axis of the femur and knee transverse axis.  E: the Inferolateral angle formed by the transverse axis of the ankle and the anatomical axis of the tibia.  F: the Lateral angle between anatomical axes of femur and tibia. G: Yielded from the intersection of lines corresponding distal femur and proximal tibia that is referred to as joint line congruence angle. H: Resulted from two lines perpendicular to tibia plateau and transverse axis of the ankle. This was further selected to evaluate tibia vara because in most measurements of Iranian cases anatomical and mechanical tibia axes did not match each other. Finally, femur length was measured as the distance between the uppermost part of femur head to the center of knee transverse line and tibia length as the distance between tibial spines to the center of ankle transverse line. A calibrated goniometer was used to measure the angles during the two measurements. A finally rechecked average by the senior author was assigned as recorded value (mean ± standard deviation). The t-test was applied for comparison of mean values among genders. Analyzes were also made to find any correlation between variables.  Results  From a total of 100 volunteers entered the study, mean ages were 24.4±3.8 years for men and 25.5±4.1 years for women. Averages of height were also calculated 176.1 ± 6.8 and 163.1 ± 5.8 centimeters, for males and females, respectively. The Mean weight was 70.8 ± 11 kilograms for men and 63.7 ± 11 for women. Neither of mentioned demographic characteristics was statistically different in comparison among genders. The results related to alignment view values are summarized in table 1.  Angle A depicts an overall alignment of the lower extremity. Thus, angle of less than 180 degrees denotes varus alignment. We observed significantly higher varus in men (2.5 ± 3º) than in women (0.7 ± 3º) in Iranian population.  M. Jabalameli, et al. Acta Medica Iranica, Vol. 53, No. 5 (2015)    295 Angle B is considered as an index of the obliquity of the knee joint. The surface would be medially inclined if the angle is larger than 90 degrees. In current male volunteers, this varus of the proximal tibia was calculated 3.6 ± 1.7 degrees that revealed remarkable difference comparing with female ones (2 ± 2º). Angle F is the summation of angles B and D. It renders apparent alignment of lower extremities based on anatomical axes. We measured a mean valgus of 4.12º and 2.77º in present female and male subjects, respectively. Angle G designates knee joint line congruence angle. This was medially inclined in all of the participants. Tibila length showed a significant difference between genders. Analysis revealed a correlation between tibial length with knee medial inclination(r=0.25) and femur mechanical-anatomical angle (r=-0.35), and also between angle age and lateral distal femoral (D) angle (r=0.25).  Table 1. Comparison of lower limb alignment values reported from this survey and some reference studies  Present study Moreland2 (Caucasian) Tang et al.8 (Chinese) Hsu et al.3 (white pop.) Khattak9 (Pakistani)  Total Male Female A 178.5±2.9177±3.1 179.3±2.7 178.5± 2.0 177.8 ± 2.7 177.7± 2.3 178.4±2.8 B 92.8±2 93.6±1.7 92±2 93.0 ± 1.6 94.9 ± 2.3 91.0± 1.4 93.4±2.2 C 5.7±1.2 5.7±1 5.7±1.4 5.8 ± 0.7 5.6 ± 0.8 -- 5.4º±1.32 D 83.2±3 83.5±3.3 82.8±2.7 -- -- --  E 91.7±2.8 91.8±2.6 91.6±3 90.7 ± 3.2 91.4 ± 3.1 -- 91.7±1.9 F 176.1±3.4* 177.2±3.7 174.8±2.8 -- -- -- -- G 1±1.6 1±1.4 0.97±1.7 -- -- 1±1.4(male)/ 0.1±1.9(fem.) -- H 0.93±3.8 1.1±3.4 0.72±3.4 -- -- -- -- Femoral length 47.1±6.8 49.3±3.9 44.8±8.4 -- -- -- -- Tibial length 39.8±3.7* 41.4±1.1 38.3±1.9 -- -- -- -- * denotes significant difference between genders in present study  Discussion  Orthopedic knee operations such as high tibia osteotomy or TKA often aim at correction of a deformity toward normal alignment. However, such normal anatomy remained an area of controversy because of the substantial ethnical variations (2,3). Current recommendations applied by designers of a total knee arthroplasty systems are based on alignment values documented by Moreland et al., on Caucasians and Hsu et al. on white subjects. Several studies were also conducted during last decade to evaluate these normative in Chinese, Korean and Pakistani population. In the present study over Iranian population, mechanical axes of the femur and the tibia (angle A) did not yield a straight line in either gender. Overall knee varus of 1.5 degrees was measured. This was along with findings of Tang et al., (8) and in contrast to the general consensus described that mechanical axes of femur and tibia are aligned (4,10). To justify this difference, two points should be noticed. One is more medial inclination (angle B) of the knee beside increased joint line congruence angle (angle G) and the other is apparently higher amount of tibia vara in Iranian population that is less scrutinized in similar studies. Varus alignment was significantly higher among men although Tang reported slightly higher varus in female volunteers. Angle B is complementary to the commonly used medial proximal tibial angle (MPTA) and can be implied as an indicator of medial joint inclination. Present male participants like Pakistani population had the significantly higher medial inclination. This was contrary to what observed in white and Chinese studies (3,8). The amount of this inclination should be taken into consideration while determining the amount of femoral cut external rotation in TKA if the tibial cut is placed perpendicular to the mechanical axis (4). It seems that an average of 3.65 degrees of external rotation of the femoral component may produce a rectangular flexion gap in Iranian patients. The angle formed by the mechanical axis of the femur and the femoral anatomical II (angle C) has implication in performing proper distal femoral cut during total knee arthroplasty. In current systems with Parameters of lower extremities alignment view  296    Acta Medica Iranica, Vol. 53, No. 5 (2015)   an intramedullary guide for the femoral cut, most of the instrumentations offer a standard six degree cutting block to match the commonly reported physiological valgus angulation of the femur (3,4,11). This guide route is believed to be best represented by femoral anatomical axis II, as applied in previous studies (3,8). The Current value of 5.7±1.2 degrees was similar to other surveys measurement. Respecting correct placement of femoral guide entry hole, the medial shift from the apex of the intercondylar notch should be taken into consideration. The femoral bow is also posed as an important determinant. However, the amount of the medialization and/or choice of the short intramedullary rod (as proposed by some authors in the highly bowed femur) should be individualized according to the preoperative planning. Of note, designers of some systems assumed smaller cutting block angle in taller individuals supposing that taller patients enjoy a smaller physiological valgus angle of the femur (12). We did not find such correlation during the analysis of present data. Lateral distal femoral angle (LFDA) is derived from angles C and D. It is sometimes assumed to be equal to the medial proximal tibial angle (MPTA) (1). We calculated mean LDFA as 88 degrees and based on the results they were not equal. Thus it is proposed to measure them discretely.   The ankle is reported to have a valgus of 0-1 degree in different studies (2,8,9). Although it was not statistically significant, we observed more valgus in the current population, and this may in part be due to compensation of higher knee varus. Epidemiology studies imply geographical variation in prevalence of osteoarthritis. The ratio of knee:hip osteoarthritis is reported 9:1 for Chinese as an example of Asian population (13), comparing with 3:1 for white individuals of United States, and 1:2 for Swedish (14). The racial differences in the axial alignment of the lower extremity may justify the discrepancy (15). Along with Chinese and Pakistani population, we found larger knee-joint-obliquity angle in the present study. Current designs of total knee arthroplasty should take these differences into consideration to provide optimal outcomes.  References  1. Lotke PA, Ecker ML. Influence of positioning of prosthesis in total knee replacement. J Bone Joint Surg Am 1977;59(1):77-9. 2. Moreland JR, Basset LW, Hanker GJ. Radiographic analysis of the axial alignment of the lower extremity. J Bone Joint Surg Am 1987;69(5):745-9. 3. Hsu RW, Himeno S, Coventry MB, et al. Normal axial alignment of the lower Extremity and load bearing distribution at the knee. Clin Orthop 1990;255:215-27. 4. Insall JN. Surgical technique and Instrumentation in total knee arthroplasty: surgery of the knee. J N Insall RE Ed 1993;2:739-804. 5. Tamari K, Tinley P, Briffa K, et al. Ethnic-, Gender-, and Age-Related Differences in Femorotibial Angle, Femoral Antetorsion, and Tibiofibular Torsion. Clin Anat 2006;19(1):59-67. 6. Clarke HD, Hentz JG. Restoration of Femoral Anatomy in TKA With Unisex and Genderspecific Components. Clin Orthop Relat Res 2008;466(11):2711-6. 7. Vaidya SV, Ranawat CS, Aroojis A, et al. Anthropometric measurements to design total knee prostheses for the Indian population. J Arthroplasty 2000;15(1):79-85. 8. Tang WM, Zhu YH, Chiu KY. Axial alignment of the lower extremity in Chinese adults. J Bone Joint Surg Am 2000;82-A(11):1603-8. 9. Khattak M, Umer M, Davis ET, et al. Lower-limb alignment and posterior tibial slope in Pakistanis: a radiographic study. J Orthop Surg (Hong Kong) 2010;18(1):22-5. 10. Hungerford DS, Kenna RV, Krackow KA. The porous-coated anatomic total knee. Orthop Clin North Am 1982;13(1):103-22. 11. Paley D, Hergenberg JE, Tetswor K. Deformity planning for frontal and sagittal plane corrective osteotomies.  Orthop Clin North Am 1994;25(3):425-65. 12. Fang Y, et al. The biomechanical study of rotating-arm self-locking intramedullary nails in comminuted femoral shaft fractures. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2006;23(5):1041-4. 13. Hoaglund FT, Yau AC, Wong WL. Osteoarthritis of the hip and other joints in southern Chinese in Hong Kong. Incidence and related factors. J Bone and Joint Surg Am 1973;55(3):545-57. 14. Danielsson L, Hernborg J. Morbidity and mortality of osteoarthritis of the knee (gonarthrosis) in Malmo, Sweden. Clin Orthop Relat Res 1970;69:224-6. 15. Sina Shahi A, Seyyed Hosseinzadeh HR, Kazemian GH, et al. Special Considerations in Asian Knee Arthroplasty, (Accessed in March 2014, 20, at http://www.intechopen.com/books/arthroplasty-update/ special- considerations-in-asian-knee-arthroplasty).    

Parameters of lower extremities alignment view in Iranian adult population

Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 ± 1.2º. The Knee joint was shown to be medially inclined 3.6 ± 1.7º in men comparing 2 ± 2º of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 ± 1.6º. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery

Mahmoud Jabalameli

Javad Moghimi

Ali Yeganeh

Marzieh Nojomi

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Parameters of Lower Extremities Alignment View in Iranian Adult Population

Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 Â± 1.2Âº. The Knee joint was shown to be medially inclined 3.6 Â± 1.7Âº in men comparing 2 Â± 2Âº of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 Â± 1.6Âº. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery. Â© 2015 Tehran University of Medical Sciences. All rights reserved

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/277406677Parameters of lower extremities alignment view in Iranian adult populationArticle  in  Acta medica Iranica · May 2015Source: PubMedCITATIONS7READS424 authors, including:Some of the authors of this publication are also working on these related projects:What Is the Optimal Treatment for Extensor Tendon Disruption after TKA? View projectA Community Study on Attitudes to and Knowledge of Mental Illness in Tehran Article Public awareness and attitudes towards epilepsy in Tehran, Iran View projectMahmoud JabalameliIran University of Medical Sciences47 PUBLICATIONS   71 CITATIONS   SEE PROFILEAli YeganehIran University of Medical Sciences46 PUBLICATIONS   72 CITATIONS   SEE PROFILEMarzieh NojomiIran University of Medical Sciences115 PUBLICATIONS   1,470 CITATIONS   SEE PROFILEAll content following this page was uploaded by Marzieh Nojomi on 25 November 2015.The user has requested enhancement of the downloaded file. ORIGINAL ARTICLE   Corresponding Author: A. Yeganeh  Department of Orthopedic Surgery, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran  Tel: +98 9122187996, Fax: +98 --, E-mail address: yeganeh471@yahoo.com ARTICLE IN PRESS  Parameters of Lower Extremities Alignment View in  Iranian Adult Population  Mahmoud Jabalameli1, Javad Moghimi2, Ali Yeganeh2, and Marzieh Nojomi3 1 Department of Orthopedic Surgery, Shafa Yahyaiyan Hospital, Iran University of Medical Sciences, Tehran, Iran 2 Department of Orthopedic Surgery, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran 3 Department of Community Medicine, School of Medicine, Iran University of Medical Sciences, Tehran, Iran  Received: 5 Oct. 2013; Accepted: 10 Jun. 2014  Abstract- Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males & 50 females) aged between 15- 32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibio-femoral mechanical angle depicted mean varus of 1.5 degrees in Iranian population that was significantly higher in male participants. Mean angle between anatomical and mechanical axes of femur was 5.7 ± 1.2º. Knee joint was shown to be medially inclined 3.6 ± 1.7º in men comparing 2 ± 2º of women with significant difference. Joint line congruency angle was medially inclined in all of study participants with mean of 1 ± 1.6º. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery.  © 2015 Tehran University of Medical Sciences. All rights reserved.  Acta Medica Iranica, Article in Press (3 Feb 2015).   Keywords: Adult, Iran  Introduction  ??Delicate correlation exists between human anatomy and function. Adequate knowledge is necessary regarding normal biomechanics of limbs and their variations. Achieving normal axial alignment of lower limb cannot be overemphasized in reconstructive surgery of the knee, such as total knee arthroplasty and high tibial osteotomy (1). Primary reference values were documented by Moreland and Hsu based on radiographic evaluation (2, 3). Subsequently, studies were undertaken to modify the results based on age and sex. Ethnic differences gained more attention especially with advent of newer designs of TKA prostheses (4-6). A few studies surveyed anatomic differences among Asian populations (7-9). We aimed to establish the lower-limb alignment norms in Iranian population and compare them with those reported from the western and some Asian countries.   Materials and methods  During autumn 2008, a total of 200 patients of hand clinic of Shafa Yahyaian hospital (a referral orthopedic center in capital of Iran) were volunteered to enter the survey. One hundred of them were selected randomly (half of each sex) aged 15- 32 years. Previous history of pain, any deformity or surgery of the lower extremity or trauma were the exclusion criteria of the participants. A full weight-bearing anteroposterior alignment view of the entire lower limbs was performed with bare foot, patellae facing forward and full extension of knees. X-ray beam was centered on the knee at a distance of 2.5 meters. The alignment parameters were measured according Parameters of lower extremities alignment view  2    Acta Medica Iranica, Article in Press (3 Feb 2015) to the methods described by Moreland with modifications applied by Tang in Chinese population study (2, 8). First, following land marks were determined: 1) The center of the femoral head via Mose circles,  2) Knee center as midpoint between the tips of the tibial spines or center of the tibia/ femoral condyles at the level of the subchondral bone of the medial tibial plateau/ lateral femoral condyle, and  3) Ankle center as a point midway between two malleoli or talus center at the level of the subchondral bone. Moreover, the transverse axis of the knee was drawn as a line tangential to the most distal points of the femoral condyles, and transverse axis of the ankle delineating subchondral plate of the distal part of the tibia. The femur and tibia mechanical axes were sketched with lines joining the center of the knee to the center of the femoral head and the center of the knee to the center of the ankle, respectively. Anatomical axes of femur were marked in two methods: one connecting femoral shaft center I (at the midshaft level) and another connecting femoral shaft center II (10 cm proximal to knee) to the knee center. We used the latter construct in this study as it represents femoral medullary canal more closely. Five angles were defined from intersection of above mentioned landmarks (Figure 1).                        A: The medial angle formed by the mechanical axes of the femur and the tibia. B: Inferolateral angle formed by the transverse axis of the knee and the mechanical axis of the tibia that represents knee joint inclination. C: Angle between mechanical and anatomical II axes of femur. D: Lateral angle formed by the mechanical axis of the femur and knee transverse axis.  E: Inferolateral angle formed by the transverse axis of the ankle and the anatomical axis of the tibia.  F: Lateral angle between anatomical axes of femur and tibia. G: Yielded from intersection of lines corresponding distal femur and proximal tibia that is referred to as joint line congruency angle. H: Resulted from two lines perpendicular to tibia plateau and transverse axis of the ankle. This was further selected to evaluate tibia vara because in most measurements of Iranian cases anatomical and mechanical tibia axes did not match each other. Finally, femur length was measured as distance between uppermost part of femur head to the center of knee transverse line and tibia length as distance between tibial spines to the center of ankle transverse line. A calibrated goniometer was used to measure the angles during the two measurements. A finally rechecked average by senior author was assigned as recorded value (mean ± standard deviation). T test was applied for comparison of mean values among genders. Analyses were also made to find any correlation among variables.  Results  From a total of 100 volunteers entered the study, mean ages were 24.4±3.8 years for men and 25.5±4.1 years for women. Averages of height were also calculated 176.1 ± 6.8 and 163.1 ± 5.8 centimeters, for males and females, respectively. Mean weight was 70.8 ± 11 kilograms for men and 63.7 ± 11 for women. Neither of mentioned demographic characteristics was statistically different in comparison among genders. The results related to alignment view values are summarized in table 1.  Angle A depicts overall alignment of the lower extremity. Thus, angle of less than 180 degrees denotes varus alignment. We observed significantly higher varus in men (2.5 ± 3º) than in women (0.7 ± 3º) in Iranian population.  Angle B is considered as an index of the obliquity of M. Jabalameli, et al.     Acta Medica Iranica, Article in Press (3 Feb 2015)    3 the knee joint. The surface would be medially inclined if the angle is larger than 90 degrees. In current male volunteers, this varus of proximal tibia was calculated 3.6 ± 1.7 degrees that revealed remarkable difference comparing with female ones (2 ± 2º). Angle F is summation of angles B and D. It renders apparent alignment of lower extremities based on anatomical axes. We measured a mean valgus of 4.12º and 2.77º in present female and male subjects, respectively. Angle G designates knee joint line congruency angle. This was medially inclined in all of participants. Tibila length showed significant difference between genders. Analysis revealed correlation between tibial length with knee medial inclination(r=0.25) and femur mechanical-anatomical angle (r=-0.35), and also between angle age and lateral distal femoral (D) angle (r=0.25).  Table 1. Comparison of lower limb alignment values reported from this survey and some reference studies  Present study Moreland2 (Caucasian) Tang et al8 (Chinese) Hsu et al3 (white pop.) Khattak9 (Pakistani)  Total Male Female A 178.5±2.9177±3.1 179.3±2.7 178.5± 2.0 177.8 ± 2.7 177.7± 2.3 178.4±2.8 B 92.8±2 93.6±1.7 92±2 93.0 ± 1.6 94.9 ± 2.3 91.0± 1.4 93.4±2.2 C 5.7±1.2 5.7±1 5.7±1.4 5.8 ± 0.7 5.6 ± 0.8 -- 5.4º±1.32 D 83.2±3 83.5±3.3 82.8±2.7 -- -- --  E 91.7±2.8 91.8±2.6 91.6±3 90.7 ± 3.2 91.4 ± 3.1 -- 91.7±1.9 F 176.1±3.4* 177.2±3.7 174.8±2.8 -- -- -- -- G 1±1.6 1±1.4 0.97±1.7 -- -- 1±1.4(male)/ 0.1±1.9(fem.) -- H 0.93±3.8 1.1±3.4 0.72±3.4 -- -- -- -- Femoral length 47.1±6.8 49.3±3.9 44.8±8.4 -- -- -- -- Tibial length 39.8±3.7* 41.4±1.1 38.3±1.9 -- -- -- -- * denotes significant difference among genders in present study  Discussion  Orthopaedic knee operations such as high tibia osteotomy or TKA often aim at correction of a deformity toward normal alignment. However, such normal anatomy remained an area of controversy because of the substantial ethnical variations (2, 3). Current recommendations applied by designers of most total knee arthroplasty systems are based on alignment values documented by Moreland et al on Caucasians and Hsu et al. on white subjects. Several studies were also conducted during last decade to evaluate these normative in Chinese, Korean and Pakistani population. In present study over Iranian population, mechanical axes of the femur and the tibia (angle A) did not yield a straight line in either gender. Overall knee varus of 1.5 degrees was measured. This was along with findings of Tang et al., (8) and in contrast to the general consensus described that mechanical axes of femur and tibia are aligned (4,10). To justify this difference two points should be noticed. One is more medial inclination (angle B) of the knee beside increased joint line congruency angle (angle G) and the other is apparently higher amount of tibia vara in Iranian population that is less scrutinized in similar studies. Varus alignment was significantly higher among men although Tang reported slightly higher varus in female volunteers. Angle B is complementary to commonly used medial proximal tibial angle (MPTA) and can be implied as indicator of medial joint inclination. Present male participants like Pakistani population had significantly higher medial inclination. This was contrary to what observed in white and Chinese studies (3,8). Amount of this inclination should be taken into consideration while determining amount of femoral cut external rotation in TKA if tibial cut is placed perpendicular to the mechanical axis (4). It seems that average of 3.65 degrees of external rotation of the femoral component may produce a rectangular flexion gap in Iranian patients. The angle formed by the mechanical axis of the femur and the femoral anatomical II (angle C) has implication in performing proper distal femoral cut during total knee arthroplasty. In current systems with intramedullary guide for the femoral cut, most of the instrumentations offer a standard six degree cutting Parameters of lower extremities alignment view  4    Acta Medica Iranica, Article in Press (3 Feb 2015) block to match the commonly reported physiological valgus angulation of the femur (3,4,11). This guide route is believed to be best represented by femoral anatomical axis II, as applied in previous studies (3,8). Current value of 5.7±1.2 degrees was similar to other surveys measurement. Respecting correct placement of femoral guide entry hole, medial shift from the apex of the intercondylar notch should be taken into consideration. Femoral bow is also posed as an important determinant. However, amount of the medialization and/or choice of short intramedullary rod (as proposed by some authors in highly bowed femur) should be individualized according to the preoperative planning. Of note, designers of some systems assumed smaller cutting block angle in taller individuals supposing that taller patients enjoy a smaller physiological valgus angle of the femur (12). We did not find such correlation during analysis of present data. Lateral distal femoral angle (LFDA) is derived from angles C and D. It is sometimes assumed to be equal to medial proximal tibial angle (MPTA) (1). We calculated mean LDFA as 88 degrees and based on the results they were not equal, thus it is proposed to measure them discretely.   Ankle is reported to have a valgus of 0-1 degree in different studies (2,8,9). Although it was not statistically significant, we observed more valgus in current population and this may in part be due to compensation of higher knee varus. Epidemiology studies imply geographical variation in prevalence of osteoarthritis. The ratio of knee:hip osteoarthritis is reported 9:1 for Chinese as an example of Asian population (13), comparing with 3:1 for white individuals of United States, and 1:2 for Swedish (14). The racial differences in the axial alignment of the lower extremity may justify the discrepancy (15). Along with Chinese and Pakistani population, we found larger knee-joint-obliquity angle in present study. Current designs of total knee arthroplasty should take these differences into consideration to provide optimal outcomes.  References  1. Lotke PA, Ecker ML. Influence of positioning of prosthesis in total knee replacement. J Bone Joint Surg Am 1977;59(1):77-9. 2. Moreland JR, Basset LW, Hanker GJ. Radiographic analysis of the axial alignment of the lower extremity. J Bone Joint Surg Am 1987;69(5):745-9. 3. Hsu RW, Himeno S, Coventry MB, et al. Normal axial alignment of the lower Extremity and load bearing distribution at the knee. Clin Orthop 1990;255:215-27. 4. Insall JN. Surgical technique and Instrumentation in total knee arthroplasty: surgery of the knee. J N Insall RE Ed 1993;2:739-804. 5. Tamari K, Tinley P, Briffa K, et al. Ethnic-, Gender-, and Age-Related Differences in Femorotibial Angle, Femoral Antetorsion, and Tibiofibular Torsion. Clin Anat 2006;19(1):59-67. 6. Clarke HD, Hentz JG. Restoration of Femoral Anatomy in TKA With Unisex and Genderspecific Components. Clin Orthop Relat Res 2008;466(11):2711-6. 7. Vaidya SV, Ranawat CS, Aroojis A, et al. Anthropometric measurements to design total knee prostheses for the Indian population. J Arthroplasty 2000;15(1):79-85. 8. Tang WM, Zhu YH, Chiu KY. Axial alignment of the lower extremity in Chinese adults. J Bone Joint Surg Am 2000;82-A(11):1603-8. 9. Khattak M, Umer M, Davis ET, et al. Lower-limb alignment and posterior tibial slope in Pakistanis: a radiographic study. J Orthop Surg (Hong Kong) 2010;18(1):22-5. 10. Hungerford DS, Kenna RV, Krackow KA. The porous-coated anatomic total knee. Orthop Clin North Am 1982;13(1):103-22. 11. Paley D, Hergenberg JE, Tetswor K. Deformity planning for frontal and sagittal plane corrective osteotomies.  Orthop Clin North Am 1994;25(3):425-65. 12. Fang Y, et al. The biomechanical study of rotating-arm self-locking intramedullary nails in comminuted femoral shaft fractures. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2006;23(5):1041-4. 13. Hoaglund FT, Yau AC, Wong WL. Osteoarthritis of the hip and other joints in southern Chinese in Hong Kong. Incidence and related factors. J Bone and Joint Surg Am 1973;55(3):545-57. 14. Danielsson L, Hernborg J. Morbidity and mortality of osteoarthritis of the knee (gonarthrosis) in Malmo, Sweden. Clin Orthop Relat Res 1970;69:224-6. 15. Sina Shahi A, Seyyed Hosseinzadeh HR, Kazemian GH, et al. Special Considerations in Asian Knee Arthroplasty, (Accessed in March 2014, 20, at http://www.intechopen.com/books/arthroplasty-update/ special- considerations-in-asian-knee-arthroplasty).    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Parameters of lower extremities alignment view in Iranian adult population

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