Frequency and Spectral Power Density Analysis of the Stability of Amputees Subjects

Keywords: Transtibial amputation, biomechanics, center of pressure, power spectral density, system stability


Transtibial amputations reduce the amount of somatosensorial information available to the central nervous system. This muscular and physiological loss involving the ankle joint reduces the muscle strength of the legs, which affects the balance and mobility of those who suffer from it. As lower limbs are used less, muscle hypertrophy occurs and the muscle strength deficit increases. Additionally, transtibial amputees should adapt themselves to the lack of a physiological joint between the ankle and the plantar flexor muscles, which are essential for an adequate joint mobility, muscle strength, and active adjustment capacity of the prosthesis during quiet stance. Thus, the reduction of their muscle strength is associated with compromised balance. This study analyzed the Center of Pressure (COP) of a group of transtibial amputees to understand the behavior of their stability. A harmonic analysis of the stability signs of such amputees (prosthesis users) was examined in order to reveal the behavior of their center of pressure. We analyzed two groups of 9 participants each: non-amputee control group and amputees. We used a periodogram, via Welch’s method, to find the frequential components of the center of pressure under each foot in order to characterize and detect them and understand the differences between the study groups. This paper presents the harmonic analysis of a nonstationary signal and supports the idea that the latter is an important tool for stability analysis. The results indicate that amputations have an influence on Power Spectral Density (DEP) because there is a difference in frequencies between the amputated and the non-amputated limb (greater oscillation on the amputated side, antero-posterior axis). The same situation occurred between the study groups (greater power in amputees under all testing conditions).

Author Biographies

Lely A. Luengas C.*, Universidad Distrital Francisco José de Caldas, Colombia

PhD. en Ingeniería, Facultad Tecnológica, Universidad Distrital Francisco José de Caldas, Bogotá-Colombia,

Daissy C. Toloza, Universidad Manuela Beltrán, Colombia

PhD. en Ingeniería, Ingeniería Biomédica, Universidad Manuela Beltrán, Bucaramanga-Colombia,


L. H. Lugo Agudelo y V. Seijas, “La discapacidad en Colombia: una mirada global,” Rev. Colomb. Med. Física y Rehabil., vol. 22, no. 2, pp. 164–179, 2012. Disponible en:

Dirección Contra Minas, “Víctimas de minas antipersonal y municiones sin explosionar”, Presidencia de la República de Colombia, 2018. Disponible en:

L. A. Luengas Contreras, E. Camargo Casallas, y D. Guardiola, “Modelado y simulación de la marcha protésica usando modelo en 3D de una prótesis transtibal,” Rev. Ciencias la Salud, vol. 16, no. 1, p. 82-100, Jan. 2018.

J. Ospina y F. Serrano, “El paciente amputado: Complicaciones en su proceso de rehabilitación”, Rev. Ciencias la Salud, vol. 7, no 2, pp. 36-46, May 2009. Disponible en:

L. A. Luengas C. y D. C. Toloza, Análisis de estabilidad en amputados transtibiales unilaterales. Bogotá: UD Editorial, 2019. Disonible en:

R. M. Palmieri, C. D. Ingersoll, M. B. Stone, y B. A. Krause, “Center-of-Pressure Parameters Used in the Assessment of Postural Control,” J. Sport Rehabil., vol. 11, no. 1, pp. 51–66, Feb. 2002.

J. A. Raymakers, M. M. Samson, y H. J. J. Verhaar, “The assessment of body sway and the choice of the stability parameter(s),” Gait Posture, vol. 21, no. 1, pp. 48–58, Jan. 2005.

P. J. Loughlin, M. S. Redfern y J. M. Furman, “Nonstationarities of Postural Sway”, IEEE Eng. Med. Biol. Mag., vol. 22, no. 2, pp. 69-75, Apr. 2003.

H. Van Der Kooij, E. Van Asseldonk, y F. C. T. Van Der Helm, “Comparison of different methods to identify and quantify balance control”, J. Neurosci. Methods, vol. 145, no. 1-2, pp. 175-203, Jun. 2005.

C. Fujimoto, N. Egami, S. Demura, T. Yamasoba y S. Iwasaki, “The effect of aging on the center-of-pressure power spectrum in foam posturography”, Neurosci. Lett., vol. 585, pp. 92-97, Jan. 2015.

H. Qiu y S. Xiong, “Center-of-pressure based postural sway measures: Reliability and ability to distinguish between age, fear of falling and fall history”, Int. J. Ind. Ergon., vol. 47, pp. 37-44, May. 2015.

A. J. Orozco-Naranjo y P. A. Muñoz-Gutiérrez, “Detección de latidos cardiacos patológicos y normales utilizando transformada por paquetes wavelet, máquinas de soporte vectorial y perceptrón multicapa”, TecnoLógicas, no. 31, pp. 73-91, Nov. 2011.

U. Oppenheim, R. Kohen-Raz, D. Alex, A. Kohen-Raz, y M. Azarya, “Postural characteristics of diabetic neuropathy”, Diabetes Care, vol. 22, no. 2, pp. 328-332, Feb. 1999.

P. R. Cavanagh, G. G. Simoneau, y J. S. Ulbrecht, “Ulceration, unsteadiness, and uncertainty: the biomechanical consequences of diabetes mellitus”, J. Biomech., vol. 26, no. 1, pp. 23-40, 1993.

M. Lord y D. M. Smith, “Foot loading in amputee stance”, Prosthet. Orthot. Int., vol. 8, no. 3, pp. 159-64, Dic. 1984. Disponible en:

D. A. Winter, Biomechanics and motor control of human movement, 4th ed. New Jersey: John Wiley & sons, Inc, 2009.

D. C. Hay y M. P. Wachowiak, “Analysis of free moment and center of pressure frequency components during quiet standing using magnitude squared coherence”, Hum. Mov. Sci., vol. 54, pp. 101-109, Aug. 2017.

H. Nadollek, S. Brauer, y R. Isles, “Outcomes after trans-tibial amputation: the relationship between quiet stance ability, strength of hip abductor muscles and gait”, Physiother. Res. Int., vol. 7, n.° 4, pp. 203-214, Nov. 2002.

P. R. Rougier y J. Bergeau, “Biomechanical Analysis of Postural Control of Persons with Transtibial or Transfemoral Amputation”, Am. J. Phys. Med. Rehabil., vol. 88, no. 11, pp. 896-903, Nov. 2009.

P. Hlavackova, C. Franco, B. Diot, y N. Vuillerme, “Contribution of Each Leg to the Control of Unperturbed Bipedal Stance in Lower Limb Amputees: New Insights Using Entropy”, PLoS One, vol. 6, no. 5, May. 2011.

D. A. Winter, F. Prince, J. S. Frank, C. Powell, y K. F. Zabjek, “Unified theory regarding A/P and M/L balance in quiet stance.”, J. Neurophysiol., vol. 75, n.° 6, pp. 2334-43, Jun. 1996.

R. Shiavi, Introduction to applied statistical signal analysis: guide to biomedical and electrical engineering applications, 3rd ed. Burlington: Academic Press, 2007. Disponible en:

J. S. Bendat y A. G. Piersol, Random data : analysis and measurement procedures. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010.

J. P. Carroll y W. Freedman, “Nonstationary properties of postural sway”, J. Biomech., vol. 26, no. 4-5, pp. 409-16, Apr. 1993.

M. G. Carpenter, J. S. Frank, D. A. Winter, y G. W. Peysar, “Sampling duration effects on centre of pressure summary measures.”, Gait Posture, vol. 13, no. 1, pp. 35-40, Feb. 2001.

A. Nardone, M. Grasso, y M. Schieppati, “Balance control in peripheral neuropathy: Are patients equally unstable under static and dynamic conditions?”, Gait Posture, vol. 23, no. 3, pp. 364-373, Apr. 2006.

How to Cite
Luengas C., L. A., & Toloza, D. C. (2020). Frequency and Spectral Power Density Analysis of the Stability of Amputees Subjects. TecnoLógicas, 23(48), 1-16.


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