Effects of tibial torsion on distal alignment of extramedullary instrumentation in total knee arthroplasty

Abstract

Background and purpose Whether tibial torsion affects the positioning of extramedullary instrumentation and is a possible factor in malalignment of the tibial component in total knee arthroplasty (TKA) is unknown. We assessed the influence of tibial torsion on distal alignment of extramedullary systems for TKA, using the center of the intermalleolar distance as anatomical reference at the ankle joint.Patients and methods We analyzed CT scans of knee and ankle joints of 50 patients with knee osteoarthritis (mean age 73 years, 52 legs). The tibial mechanical axis was identified and translated anteriorly at the level of the medial one-third (proximal AP axis 1), at the medial border of the tibial tuberosity (proximal AP axis 2), and at the level of the talar dome (distal AP axis). The center of the intermalleolar distance and the width of the medial and lateral malleolus were calculated. The proximal AP axes 1 and 2 were translated at the level of the ankle joint and any difference between their alignment and the distal AP axis was calculated as angular and linear values.Results The center of the ankle joint was located, on average 2 mm medial to that of the intermalleolar distance. The distal AP axis was externally rotated by 18° and 27° compared to the proximal AP axes 1 and 2, respectively. Overall, the center of the ankle joint was shifted laterally by 9–11 mm with respect to the proximal AP tibial axes.Interpretation To avoid a varus tibial cut in TKA, extramedullary alignment systems should be aligned more medially at the ankle joint than previously thought, due to the effect of tibial torsion and—to a lesser extent—to the different malleolar width.

Total knee replacement modifies the preoperative tibial torsion angle—similar results between computer-assisted and standard technique

“…However, tibial torsion showed a wide range of variation in the series analyzed. In the literature the range of external rotation varies between 50º and 15º (8,13,16,32,33) depending on patient race, personal characteristics, the anatomical reference used in the proximal zone and ankle, or the radiological technique used. These results may further explain the higher rate of outliers found on studying the rotation of the components in TKR (16).…”

“…In the literature the range of external rotation varies between 50º and 15º (8,13,16,32,33) depending on patient race, personal characteristics, the anatomical reference used in the proximal zone and ankle, or the radiological technique used. These results may further explain the higher rate of outliers found on studying the rotation of the components in TKR (16). In our study the mean preoperative tibial torsion angle was 23.04º (SD =6.78) on considering the tangent posterior to the tibial plateau and the axis of the ankle, and 17.76º (SD =10.15) on considering the line joining the centres of the tibial plateaus and the axis of the ankle.…”

“…Different references have been considered in the proximal tibia (4)(5)(6)(7)(8)(9), and varus cuts have been shown to be the most frequent error when implanting this component (10)(11)(12)(13). Neither technique is completely satisfactory and defective alignment has been reported in 2-40% of the cases (14)(15)(16).…”

Preoperative Measurement of Tibial Resection in Total Knee Arthroplasty Improves Accuracy of Postoperative Limb Alignment Restoration

“…For example, foot supination and tibial torsion are common anatomical features that can affect the identification of distal landmarks of the tibial mechanical axis. [61920]…”

The risk of violating the posterior malleolar fracture when nailing the ipsilateral concomitant spiral distal tibial fracture

“…After reconstruction of the leg, the simulated vIM nail was devised step by step with a reproducible method. First, as the ideal position of the tibial nail axis is across the center of the ankle, this point and its sagittal plane projection were established on axial scan according to Cinotti’s method [ 10 ]. This method is precise [ 11 ] and easy to perform by identifying the center of the talar dome originating from the connection of 2 points located in the middle of its anterior and posterior region.…”