Methods for Measurement of Tibial Torsion

No conventional technique for routine assessment of tibial torsion, the twisting of tibia around the longitudinal axis, has yet gained acceptance. Clinical measurements give approximate values only. Methods employing tropometers and other mechanical devices have mainly been used for measurement in skeletal specimens and in patients, though on a limited scale. Certain roentgenographic methods are considere d complicated, whereas others re q u i re trigonometric Abdulla Ahmed Eyadah, Maria Kondeva Ivanova Physical Medicine and Rehabilitation Hospital, Kuwait calculations on the roentgenograms. With the development of the whole body computed tomography (CT) where distinct cross-sectional images can be obtained, reference points are easy to be determined, which make it possible to accurately measure this torsional deformity. Considering the demands for a v a i l a b i l i t y, simplicity, and precision, fluoro s c o p i c techniques have been developed. INTRODUCTION Va rus, valgus and other axial deformities are well known in osteoarthritis of the knee joint, but the coexistence of torsional deformity is a re c e n t addition to our knowledge. In clinical practice, adduction of the foot in a patient standing with the patella facing directly forward results from torsional deformity and is generally called internal tibial torsion. Torsional abnormalities are considered by some authors to be a possible cause or result of gonarthrosis. In the opinion of some authors, torsional deformities must be corrected at the same time as axial deformities [ 2 . The importance of understanding and evaluating rotational alignment of the lower extremity in connection with surgical planning of the arthritic knee has been emphasized. Consequently, it is important to the understanding of the pathogenesis of osteoarthritis of the knee, as well as for compound treatment of it, whether torsional deformity is present and to measure it. Torsional deformities of the tibia have been reported to be associated also with club foot, patello-femoral instability 11 , 1 2 , and Osgood–Schlatter’ s disease. Tibial torsion can be defined as a physiologic twist of the distal versus the proximal articular axis of the tibial bone in the transverse plane. The definition of tibial torsion put forward by Le D a m a n y 1 3 ] was based on studies in cadavers. Since then, various clinical, arthropometric and radiological methods have been used to determine tibial torsion. Depending on which points of re f e rence are chosen at the proximal and distal end of tibia, the re c o rded values for tibial torsion in the diff e rent studies will vary and are not directly comparable (Table 1). Mechanical Methods On necropsy specimens, tibial torsion may be m e a s u red using anthro p o m e t r y. The angle between a pin passed through the condylar axis of the head of the tibia and another one through the distal surface of the tibia is measured. This is the most accurate technique but the disadvantage is that this method cannot be used clinically. In 1909, Le Damany 1 3 ] reported that the mean lateral tibial torsion m e a s u red by anthropometry using Bro c a ’ s i n s t rument was 23.7 degrees. Other studies h a v e reported clinical values employing instru m e n t s similar to the anthro p o m e t e r. They used the patella or tibial tuberosity and the malleoli as re f e re n c e points. Difficulty in centering the instrument on the mobile patella or the tibial tubercle decreases the accuracy of these methods. There f o re, methods employing tropometers or other mechanical devices have been used mostly for measurements in specimens and in patients, though on a limited scale. CLINICAL METHODS A simple clinical method is to have the patient sit with the legs hanging over the edge of the