Why is the Tibial Tuberosity an Unreliable Landmark for Rotational Alignment of Tibial Component in Total Knee Arthroplasty?
Murat Bozkurt MD1*, M. Gulbiz Kartal MD2, Safa Gursoy MD1, Mustafa Akkaya MD1, Cetin Isik MD1, Nurdan Cay MD3
1 Yildirim Beyazit University, Dept. of Orthopaedics and Traumatology, Ankara, Turkey
2 Istanbul University, Dept. of Radiology, Ankara, Turkey
3 Yildirim Beyazit University, Dept. of Radiology, Ankara, Turkey
* Corresponding Author
Introduction: The rotational alignment of the tibia is an unresolved issue in knee replacement. Several anatomic landmarks have been used as reference for rotational positioning of the components. Among these, mostly preferred one by the surgeons is the tibial tuberosity. Previous studies have reported that tibial tuberosity is not a reliable reference. The aim of this study is to evaluate variations in tibial tuberosity position and proximal tibial torsion.
Materials and methods: Thirty-nine dry tibias were scanned in MDCT. Axial slices were taken parallel to the short axis of the bone. To evaluate proximal tibia we have measured (1) the position of the tubercle with respect to tibial spines, (2) degree of rotation between the tibial tuberosity and geometric center of the bone, (3) degree of rotation between the tibial tuberosity and anatomic axis of the bone, (4) degree of torsion of the tibia and proximal tibia.
Results: In 6 out of 39 bones (15.38%), the tibial tubercle was positioned medial to the lateral eminence. The distance between the tubercle and lateral eminence changed between 0.7 – 17 mm (mean = 6.2 ± 5.3 mm). The torsion showed significant variance in each bone.
Conclusion: Tibial tubercle shows great variations in sagittal axis, due to the variations in structure of the bones. Individual planning for each bone may be assessed particularly with CT before the operation.
Keywords: Rotational alignment, Total knee arthroplasty, Tibial component, Tibial tuberosity, Orthopaedics, A.7, A.10