Validity and reliability of existing and modified clinical methods of measuring femoral and tibiofibular torsion in healthy subjects: Use of different reference axes may improve reliability

Abstract

Previous studies have evaluated reliability and validity of clinical measurements of femoral and tibiofibular torsion, however, the results are conflicting, warranting an alternative method. The authors developed modified methods of measuring femoral and tibiofibular torsion using different reference axes, and validity and reliability of the modified and existing methods were examined in healthy subjects. Reference values were established using magnetic resonance imaging (MRI) for the validity study. There were significant differences between all clinical methods and corresponding MRI outcomes (P <0.05), whereas Pearson's correlation coefficients between the clinical methods and MRI ranged from 0.67-0.92. For modified methods, intraclass correlation coefficients were 0.89-0.97, whereas those of existing methods were 0.75-0.81. Modified methods were more precise, with standard error of measurements (SEM) of 1.5-2.9 degrees , compared to existing methods (SEM=4.0-5.1 degrees). These results indicate that clinical methods available currently do not accurately measure true torsion of the femur and tibia. Nevertheless, the clinical methods may be useful for screening and descriptive purposes as indices of true torsion, and use of different reference axes could improve their reliability.

The Association between Idiopathic Clubfoot and Increased Internal Hip Rotation

“…The literature documents the reproducibility of the clinical assessment of torsion to within 4°, regardless of the specific clinical method used by the individual investigator, in multiple studies spanning four decades [1,3,4,9,19,21,23,28,32,33]. Our finding of greater than 10°of relative internal hip rotation in an extremity with a clubfoot compared with an unaffected limb notably falls beyond this measurement, thereby increasing confidence in the validity of our data.…”

“…Our finding of greater than 10°of relative internal hip rotation in an extremity with a clubfoot compared with an unaffected limb notably falls beyond this measurement, thereby increasing confidence in the validity of our data. Other studies support the assertion that physical examination is more clinically valid than imaging modalities such as CT and MRI in evaluating torsion [12,16,28,33].…”

“…Moreover, several studies have established the reproducibility of the routine clinical assessment of torsional alignment that is most often used by the pediatric orthopaedist [1,3,4,9,19,21,28,32,33]. This information helps to justify the use of the physical exam, in contrast to imaging studies, because it is reproducible, quick, inexpensive, avoids radiation exposure, and measures what we observe clinically.…”

“…In the orthopaedic literature and in conversations among many orthopaedists, greater than average internal hip rotation combined with less than average external hip rotation has generally been equated with femoral anteversion, despite the fact that rotational motion at the hip joint does not necessarily accurately represent the torsional shape of the femur [1,3,4,9,19,21,28,32,33]. This is in contrast to the clinical assessment of tibial torsion in which the torsional shape of that bone is measured directly by comparing the axis of the foot to that of the femur when the knee is flexed 90°and the ankle is in neutral dorsiflexion.…”

Tibial Torsion in Cerebral Palsy: Validity and Reliability of Measurement

“…Its use has been advocated in numerous studies [2,3,7,11,12,25]. Other methods such as MRI [17,18,24] and ultrasound [2,10] also are valid tools for measuring the level of tibial torsion and can be used as reference standards. However, because CT was invented earlier, studies on the validity of MRI and ultrasound have used CT as the reference standard [2,18].…”