Tibial Torsion in Cerebral Palsy: Validity and Reliability of Measurement

Abstract

Physical examinations of tibial torsion are used for preoperative planning and to assess outcomes of tibial osteomy in patients
with cerebral palsy (CP). The thigh-foot angle (TFA) and transmalleolar axis (TMA) are commonly used, and the second toe test
recently was introduced. However, the validity and reliability of the three methods have not been clarified. This study was
performed to evaluate the validity and reliability of these physical measures. We recruited 18 patients (36 limbs) with CP.
During reliability sessions, three raters with various levels of orthopaedic experience independently measured tibial torsion
using the three different methods during one day before surgery. Validity was assessed by performing a correlation study between
physical examination and two-dimensional computed tomographic (CT) findings. Interobserver reliability was greatest for the
TMA followed by TFA and then by the second toe test with intraclass correlation coefficients of 0.92, 0.74, and 0.57, respectively.
In terms of the concurrent validity, the correlation coefficients (r) for the CT measurements were 0.62, 0.52, and 0.55. When
depicting tibial torsion by physical examination, all three methods had substantial validity, but test reliability and validity
were highest for TMA measurements.

Level of Evidence: Level I, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.