A Validated, Automated, 3-Dimensional Method to Reliably Measure Tibial Torsion

Abstract

Background: Tibial torsion is a twist in the tibia measured as an angle between a proximal axis line and a distal axis line. Abnormal torsion has been associated with a variety of painful clinical syndromes of the lower limb. Measurements of normal tibial torsion reported by different authors vary by 100% (ranging from 20° to 42°), making it impossible to determine normal and pathological levels. Purpose: To address the problem of unreliable measurements, this study was conducted to define an automated, validated computer method to calculate tibial torsion. Reliability was compared with current clinical methods. The difference between measurements of torsion generated from computed tomography (CT) and magnetic resonance imaging (MRI) scans of the same bone, and between males and females, was assessed. Study Design: Controlled laboratory study. Methods: Previous methods of analyzing tibial torsion were reviewed, and limitations were identified. An automated measurement method to address these limitations was defined. A total of 56 cadaveric and patient tibiae (mean ± SD age, 37 ± 15 years; range, 17-71 years; 28 female) underwent CT scanning, and 3 blinded assessors made torsion measurements by applying 2 current clinical methods and the automated method defined in the present article. Intraclass correlation coefficient (ICC) values were calculated. Further, 12 cadaveric tibiae were scanned by MRI, stripped of tissue, and measured using a structured light (SL) scanner. Differences between torsion values obtained from CT, SL, and MRI scans, and between males and females, were compared using t tests. SPSS was used for all statistical analysis. Results: When the automated method was used, the tibiae had a mean external torsion of 29°± 11° (range, 9°-65). Automated torsion assessment had excellent reliability (ICC, 1), whereas current methods had good reliability (ICC, 0.78-0.81). No significant difference was found between the torsion values calculated from SL and CT ( P = .802), SL and MRI ( P = .708), or MRI and CT scans ( P = .826). Conclusion: The use of software to automatically perform measurements ensures consistency, time efficiency, validity, and accuracy not possible with manual measurements, which are dependent on assessor experience. Clinical Relevance: We recommend that this method be adopted in clinical practice to establish databases of normal and pathological tibial torsion reference values and ultimately guide management of related conditions.

Development and Validation of a Mobile Application for Measuring Tibial Torsion

“…Tibial torsion lacks a single, reliable method for measurement 6,7 . CT, the standard tool for measuring tibial torsion, has been associated with excellent reliability and validity 20 .…”

“…A common, reliable method for the measurement of tibial torsion is lacking 6,7 . Physical examination, computed tomography (CT), and the EOS imaging system are used collectively to measure tibial torsion.…”

Torsional Abnormality: The Forgotten Issue in the Diagnosis and Treatment of the Anterior Knee Pain Patient

“…Limb alignment on the transverse plane is hard to see and difficult to measure. Currently, there is no consensus on how to measure torsion [ 10 , 11 ], and we must note that accurate measurement of torsion is essential to diagnosis, correct surgical decision-making, and preoperative planning of a rotational osteotomy (i.e., the amount of correction needed).…”

“…The first problem that is faced when we see a patient with a torsional abnormality is to recognize it and then to measure it [ 10 , 11 ]. Recognition and measurement of torsion by physical examination is somewhat subjective and unreliable.…”

“…This must be considered especially when planning a rotational osteotomy in patients with severe femoral torsional abnormalities to avoid mistakes in preoperative planning. In summary, the fact that there is no consensus [ 10 , 11 ] as to how to measure torsion leaves the orthopedic surgeon in doubt about the confirmation of the diagnosis and, more importantly, in doubt about the surgical planning.…”