Evaluation of a new device for measuring the leg torsion angle

Abstracts

Variações rotacionais dos membros inferiores no plano transverso são responsáveis por um grande número de doenças que acometem crianças e indivíduos adultos. Nas crianças, podemos citar como exemplo, um quadro comum, a marcha com os "pés para dentro" ("toeing in") e nos indivíduos adultos, a incapacitante artrose degenerativa dos joelhos. Enquanto as alterações ósseas localizadas no plano transverso são difíceis de serem avaliadas, as deformidades presentes nos planos frontal e sagital podem ser avaliadas facilmente através, por exemplo, de simples radiografias. Neste contexto, dentre os métodos disponíveis para o estudo rotacional da perna, não há procedimento clínico ou de imagem que reúna as características de precisão, praticidade e baixo custo. Com o intuito de preencher esta lacuna, os autores apresentam um dispositivo para aferição clínica indireta do ângulo de torção da perna para indivíduos adultos e crianças. Neste artigo, procedeu-se a avaliação e a análise de 40 membros inferiores de cadáveres adultos humanos.

Tíbia; Antropometria; Marcha

ORIGINAL ARTICLE

Evaluation of a new device for measuring the leg torsion angle

Sérgio José Lawand^I; Amâncio Ramalho Júnior^II; Ricardo Luiz Smith^III

^IDoctor Orthopedics and Traumatology for SBOT

^IIDoctor Orthopedics and Traumatology for SBOT; Orthopedist of Albert Einstein Israelita Hospital

^IIIChairman, Full Professor, Head of the Descriptive and Topographic Anatomy of the Morphological Department of UNIFESP/EPM

^{Correspondence}

SUMMARY

Variations and deformities of lower limbs involving rotation in the transverse plane are associated with many clinical problems, ranging from harmless in-toing in children to disabling degenerative osteoarthritis of the knee in adult patients.

While the bone alterations located in the transverse plane are difficult to be assessed, the frontal and sagittal deformities can be easily assessed , for instance, with the conventional radiographies.

In this context, among the most available methods for the leg rotational study, there is not any clinical or image procedure which is more accurate, practical or with low cost.

In order to solve this problem, the authors present a new device to indirect clinical standard of the leg torsion angle in adults and children. In this study, 40 lower limbs from human cadavers were assessed and analyzed.

Key words: Tibia; Anthropometry; Gait.

INTRODUCTION

The bad alignment of the lower limbs rotation during childhood is a frequent alteration that at adult life can be the cause of several clinical locomotor problems if not appropriately diagnosed and treated^{(1,8,9,10,13,15)}.

The leg torsion is the consequence of a difference between tibiofemoral joint flexion and tibiotalar axis flexion in the transverse plane, and it can be different according to the age, sex, anatomical and populational characteristics and osteoarticular clinical problems^(1,4,13).

The leg torsion angle assessment has fundamental importance in detecting and diagnosing previously several locomotors clinical problems; however the anthropometry clinical methods till now, show figures ranging from 0 to 45º, which is doubtful^(2,10,13,15).

On the other hand the tibial torsion by simple radiography is complex and unpractical^(5,7,13).

As a solution, the computerized tomography assessment has shown to be an efficient method; however have some disadvantages such as, lack of pattern and high cost which raise difficulties to the patient continues the treatment in many cases.

An anthropometry clinical device shows the figure of a leg torsion angle in an indirect way, with trigonometric accounts. The main purpose is to contribute with the leg torsion angle assessment using a simple method, easily reproduced, facilitating, then the patient treatment.

MATERIAL AND METHODS

This device consists in a mechanical apparatus which assess variable anthropometry in the frontal and sagittal leg planes determining indirectly the torsion angle. This device was made with low cost and easily availability such as : acrylic plates, three measurement rulers type glue, a wooden plaque and a few screws.

The anatomical pieces assessed belonged to the Laboratory of Anatomy of the Descriptive and Topographic Anatomy Discipline of the Morphological Department of The Federal University of São Paulo/ Paulista Medical School. This research project was approved by The Ethical and Research Committee from the same institution following the resolution of 196/96 National Healthy Institution.

The 40 lower limbs studied were disarticulated of their adult human cadavers and fixed with formaldehyde. Twenty five limbs were disarticulated from the femoral on, the other fifteen from the hemi pelvis on. The assessed part was not considered in the results.

The anthropometrical varieties studies were, 1- the intermalleolus distance, measuring the distance between the center of the medial and lateral malleolus (D); 2- The distance between the center of medial malleolus and the back shield of the device (M); 3- the distance between the center of lateral malleolus and the back of the shield device (L).

The assembling of the device consist in, 1- a principal shield support to the back part of the leg, 2- another smaller wooden shield, orthogonally joined to the proximal extremity of the first one, supporting the thigh ; 3- three rulers suited to the distal extremity of the main shield. In this assembling, the lower limbs researched were placed with the knee at 90 degree and the condyle of tibia and calcaneal plantar face resting on the main shield of the device (Figure 1).

The three measurement rulers type were set as the following: two rules were placed in the sagittal plane, movable, as they were perpendicular to the longitudinal leg axis, stopped the rotation when taken towards the malleolus; a third ruler remained guided at the frontal plane completing the set (Figure 2). The rulers had linear centimeters and accurate measurement till a decimal digit at the right.

The pair of sagittal rulers, besides having lateral-medial mobility, concurrently the third ruler had head-tail mobility on the longitudinal acrylic shield.

Finally, the shield availability and the mobility of the rulers set enabled to assess lower limbs independent of the length width and the studied side.

From the references spotted on the center of the malleolus, the distance between them at the frontal plane (D), with the direct reading at the ruler fixed at the back shield. Also, by the reading at the orientated rulers at the assessed plane, the distances between the lateral malleolus(L) and medial (M) in relation of the back shield were assessed . With the measurement cited above, the tangent arc account (1) the figure of the leg torsion angle were obtained (^{Picture 1}).

RESULTS

On a 40 samples of lower limbs the following figures angles between 18 and 27 degrees were obtained (Table 1).

The following distribution was found: 15 lower limbs had leg torsion angles between 20 degrees and 22 degrees, showed 37,5% of the sample.

The figures average of the leg torsion angle was 22,4º, with a standard deviation = 2,2º (Table 2). The variability of the figures was relatively small (the variation factor = 0,099).

The Box-plot and the histogram were compared and showed the percents of the distribution for concentration and frequency (Graph 1)

As the figures corresponded to angular measurement, a specific statistics method was used for the circular data (^{Graph 2}). The circular average which represents the medium angle, suited to the descriptive average (22,4º) and circular variation sample, the figure that corresponds to a variability of an average about the medium angle, was the same to 0,001 confirming the sample homogeneity

DISCUSSION

The human beings show unique biomechanical characteristics, and these characteristics are more evident if compared to the same individuals species^(9,13,14).

There are several possible causes of these alterations, each of us has some variation in the articulation movement axis and the lower limbs rotation which may be temporary or definitive. The temporary ones appear during several development phases and the definitive ones in the adult life^(4,9,10).

The posture and moulding inter-uterine affect the lower limbs rotational alignment. In the fetus the hips are flexed and rotated laterally which shows the hips have bigger lateral degree rotation than the medial ones while the legs and feet are medially rotated and brought forward^(4,6,8,10) .

At the birth this posture is presented in variable degree. During the longitudinal growing, traction and muscular strength alignment as well as the static strength of body weight lead to the spontaneous and gradual resolution of the fetus posture^(3,8,13).

The thigh and leg axis rotation are linked to the hips rotation, therefore, the leg rotation and the feet movement are in accordance.

The axis rotation shows remarkable differences and it is one of the factors which distinguish each individual appearance during the bait while marching⁽⁴⁾.

In order to assess the torsion problems more accurately, Staheli et al.⁽¹⁰⁾ suggested the torsion profile study. The purpose of it is to supply more accurate figures, therefore 1000 normal lower limbs of children and adults, 221 of male and 279 female and established normal figures of the torsion and rotation profile of different ages.

The proposed torsion profile in this article consists in measuring six parameters of each lower limb individually, to know: 1- the feet progression angle; 2- the extension hips medial rotation; 3- the extension of the lateral hip rotation; 4-the-feet –leg angle; 5- the transmalleolus angle axis; 6- the foot configuration.

The obtained figure of the transmalleolus angle axis is given when the patient is in pronation, the knees flexed at 90º with the ankles in neutral position. Central spots in the medial and lateral malleolus are made and joined with a line on the feet plantar showing the transmalleolus axis. Then a line is projected in the longitudinal direction of the heel being perpendicular to the transmalleolus axis. The transmalleolus angle axis is the angular difference between this projected line in the largest heel axis and the thigh axis.

Ultimately the transmalleolus axis would be assessed the tibial torsion and the transmalleolus axis increasing according to the age with a medium figure of 20ºin the childhood may vary between 0º to 45º^(4,10).

Staheli et al. ⁽¹⁰⁾, concluded in their article, to practical objectives in case of the simple torsion problems it must be used the obtained figures by the gauge of thigh-feet angle as this method supplies similar and parallel data obtained by the transmaleolus evaluation technique ^(4,10); however, the thigh-foot angle is a combined deformity assessment of the tibial rotation and the retro-feet.

Analyzing the techniques cited above, it does not exist a simple anthropometry which assess only with the leg parameter torsion and supply more constant data.

The biomechanical of the human locomotor is complex and a difficult mechanism which works in interdependent way among the parts. Each part has unique importance and contribution, the loss or change of a component can result into important or small alterations. The only way to understand them is analyzing how each component is distributed in the individual⁽⁴⁾, as well as the importance to understand the biomechanical alterations that each clinical problems cause in the locomotor parts^(1,3,6,8,11).

The understanding of the biochemical lower limb is an essential support to the surgeon decision and it implies in the surgical plan and consequently in the post-operatory success^(4,15,13).

It is known the leg torsion degree depends on the child age and it is variable in adults. The natural evolution of the leg torsion is to rotate laterally with the age.

In 1909 LeDemany was one of the first to assess the tibial torsion in anatomical specimen^(4,5,7,10). He described that in the fetus the medial malleolus is located behind the lateral one and there is medial tibial torsion. At the birth, the malleolus extremities were flatted and for the bait time the medial malleolus was in front of the lateral malleolus and there was around 20º tibial torsion. He also found a normal adult individual with normal lateral tibial torsion with the average of 23,7º^(2,4,7).

Staheli and Engel ⁽⁹⁾, studied the tibial torsion degree in 160 normal children and adults with a device which determined the figure of the transmalleolus axis with the knee at 90º. They observed that the torsion increases according to the age, occurring at the first year of life increased 5º lateral rotation, 10º in older children, and 20º in adults. This method had few details and it seems to have been put aside by the author in his more recent article of 1985⁽¹⁰⁾.

The device presented can be considered as improvement of what was showed by Staheli and Engel⁽⁹⁾, besides what has been presented, it is added the fact of the radiographic methods can not be used with babies or small children due to the lack of shadow contrast projected for its cartilaginous epiphyses.

The radiographic assessment of the tibial torsion is not suggested with children having limited clinical value and the exposition to radiation is not an argument^(2,4,7,12).

Confronting the proposed method with the torsion assessment technique using computerized tomography , we have to consider the high cost of it, which is a weak point to follow the treatment, even being a smaller radiation if compared to a simple radiography it also has to be classified as a negative point^{(7, 13)}.

The medium figure of a tibial torsion in a normal adult obtained with the tomography can vary of 30º to the lateral with a standard deviation till 5º^(5,12,13). However the figures vary even more according to the study⁽⁷⁾. One of the reasons of the inconstancy is the difficulty of standardize the distal and proximal tibia referent line^(5,7,15).

CONCLUSION

Considering the several mechanical devices studies cited in the literature, the outcomes showed in this article to be suited in acceptable level for a normal individual, however other studies must be continued.

The proposed method of this article for the tibial torsion angle assessment has some advantages, such as , 1- it is a cheap equipment made of easily available material;2- the use is not complicated therefore a little training for physicians or no physicians is need; 3- the method is not so severe, consequently convenient to the laboratorial following; 4- the figures obtained are compatible with the ones in the literature.

ACKNOWLEDGEMENTS

Ângela Tavares Paes, Statistics Master at the Epidemiology and Statistics Laboratory (ESL) of the Dante Pazzanese Cardiology Institute.

REFERÊNCIAS BIBLIOGRÁFICAS

Work developed in the Descriptive and Topography Anatomy Discipline of the morphological department.

• 1. Cameron JC, Saha S. External tibial torsion: an underrecognized cause of recurrent patellar dislocation. Clin Orthop 328:177-184, 1996.
• 2. Clementz BG. Assessment of tibial torsion and rotational deformity with a new fluoroscopic technique. Clin Orthop 245:199-209, 1989.
• 3. De Alba CC, Guile JT, Bowen JR, Harckle HT. Computed tomography for femoral and tibial torsion in children with clubfoot. Clin Orthop 353:203-209, 1998.
• 4. Inman VT. Introduction. In: Inman VT, Ralston HJ, Todd F. Human Walking. Baltimore: Willians & Wilkins, 1981. p.15-21.
• 5. Jend HH, Heller M, Dallek M, Schoettle H. Measurement of tibial torsion by computer tomography. Acta Radiol Diag 22:271-276, 1981.
• 6. O'Connell AP, D'Souza L, Dudeney S, Stephens M. Foot deformities in children with cerebral palsy. J Pediatr Orthop 18:743-747, 1998.
• 7. Reikeras O, Hoiseth A. Torsion of the leg determined by computed tomography. Acta Orthop Scand 60:330-333, 1989.
• 8. Reikeras O, Kristiansen LP, Gunderson R, Steen H. Reduced tibial torsion in congenital clubfoot: CT measurements in 24 pacients. Acta Orthop Scand 72:53-56, 2001.
• 9. Staheli LT, Engel GM. Tibial Torsion: a method of assessment and a survey of normal children. Clin Orthop 86:183-186, 1972.
• 10. Staheli LT, Corbett M, Wyss C. Lower extremity rotational problems in children: normal values to guide management. J Bone Joint Surg Am 67:39-47, 1985.
• 11. Stanitski CL, Christopher SL, Deborah FS. Tibial torsion in chronic , stable slipped capital femoral epiphyses: Evaluation by CT scan. J Pediatr Orthop 17:657-658, 1997.
• 12. Stuberg W, Temme JL, Kaplan P, Clarke A, Fuchs R. Measurement of tibial torsion and thigh-foot angle using goniometry and computed tomography. Clin Orthop 272:208-212, 1991.
• 13. Tachdjian MO. O pé e a perna. In: Ortopedia Pediátrica. 2ª ed. São Paulo: Manole, 1995.p.2826-2833.[1ª tradução brasileira].
• 14. Weinstein SL. The Pediatric Foot. In: Weinstein SL, Buckwalter JA. Turek's Orthopaedics: Principles and their Application. 5^th ed. Philadelphia: J.B. Lippincott Company,1994. p.646-650.
• 15. Yagi T, Sasaki T: Tibial torsion in patients with medial type osteoarthritic knee. Clin Orthop 213:177-182, 1986.

Publication Dates

• Publication in this collection
  16 June 2004
• Date of issue
  June 2004

History

• Accepted
  05 Apr 2004
• Received
  17 June 2003