Is the preoperative leg axis similar in radiographic and computer measurements in frontal deformities?
¿El eje de la pierna preoperatoria es similar en las mediciones radiográficas y computacionales en las deformidades frontales?
Daniel Hernández-Vaquero, Alfonso Noriega-Fernández, Sergio Roncero-González
Abstract
Introduction: A prerequisite for ensuring a good clinical and functional outcome in total knee arthroplasty is knowing the preoperative leg alignment. This alignment is obtained using a long radiograph including the hip and knee, or a computer algorithm derived from palpation of landmarks and mapping of bone structures. It has been recommended to omit the preoperative radiograph if technology-assisted systems are to be used, but doubts exist regarding the similarity between both measurements, especially in frontal varus or valgus deformities.
Material and methods: The preoperative leg alignment was analyzed in 123 patients scheduled for total knee arthroplasty. Thirty-eight had a preoperative valgus axis radiographically, and 85 had a varus axis. A computer program was used to perform the radiographic measurement of the mechanical axis of the leg, and at the start of the procedure, this same measurement was verified with a technology-assisted navigation system (TAS).
Results: In the valgus group, the mean preoperative radiographic axis was 169.1º (SD 5.06), while the axis measured using the TAS was 171.9º (SD 3.96) (p=0.009). In the varus group, the mean radiographic axis was 191.9º (SD 5.86), and the axis measured using the TAS was 189.7º (SD 4.84) (p=0.008). The Pearson correlation coefficient comparing both measurements was 0.650 in the varus group and 0.237 in the valgus group (p=0.151).
Conclusions: The discrepancy between limb axis measurements obtained radiographically and those obtained with technological aids does not preclude the use of radiography in the preoperative evaluation of total knee arthroplasties.
Keywords
Resumen
Introducción: Una condición imprescindible para asegurar un buen resultado clínico y funcional de la artroplastia total de rodilla es conocer la alineación previa de la pierna. Para obtener esta alineación se utiliza la radiografía larga incluyendo cadera y rodilla o un algoritmo informático conseguido a partir de palpación de referencias y mapeo de estructuras óseas. Se ha recomendado obviar la radiografía previa si se va a utilizar sistemas asistidos con tecnología, pero existen dudas en cuanto a la similitud entre ambas mediciones, sobre todo en deformidades frontales en varo o valgo
Material y métodos: Se ha analizado la alineación preoperatoria de la pierna en 123 pacientes que iban a ser intervenidos para implantar una artroplastia total de rodilla. Treinta y ocho tenían radiográficamente un eje preoperatorio en valgo y 85 en varo. Se utilizó un programa informático para realizar la medición radiográfica del eje mecánico de la pierna y al iniciar el procedimiento se comprobó esta misma medición con un sistema de navegación con ayuda tecnológica (TAS).
Resultados: En el grupo de valgo el eje preoperatorio radiográfico medio fue de 169.1º (SD 5.06) y el que se mostró mediante el TAS fue de 171.9º (SD 3.96) (p=0.009). En el grupo de varo la media radiográfica fue de 191.9º (SD 5.86) y el mostrado por la TAS de 189.7º (SD 4.84) (p=0.008). El coeficiente de correlación de Pearson comparando ambas mediciones fue de 0.650 en el grupo de varos y 0.237 en el de valgos (p=0.151).
Conclusiones: La discordancia entre la medición del eje de la extremidad obtenida radiográficamente o con sistemas de ayuda tecnológica no permite obviar la realización de una radiografía en el estudio preoperatorio de las artroplastias totales de rodilla.
Palabras clave
References
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Submitted date:
07/15/2025
Reviewed date:
11/26/2025
Accepted date:
12/13/2025
Publication date:
12/16/2025
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