Feasibility of a Novel Tibial Sighting Device Combined with Intramedullary Femoral Localisation on the Rotational Alignment of the Tibial Component for Oxford Unicompartmental Knee Arthroplasty

Abstract

Background：The success of unicompartmental knee arthroplasty (UKA) depends on perfect prosthesis component alignment. However, it is difficult to identify the anteroposterior axis and implant components in the correct rotational position in a narrow operating field in a UKA. Thus, we invented a novel tibial sighting device and explored whether combining it with intramedullary femoral localisation could be feasible on the rotational alignment of the tibial component for the Oxford UKA.Methods: Twenty consecutive knees were treated with UKA using a novel tibial sighting device combined with intramedullary femoral localisation. An equal number of patients who underwent UKA with the conventional technique were matched to the control group. Radiographic accuracy was evaluated based on the implant position in the tibial CT transverse sections. The α angles were measured between the tibial component line and the vertical line of TEA', which was projected to the trans-epicondylar axis (TEA).Results: The absolute value of the test group’s α angle was significantly smaller than the respective values of the control group (P=0.006). The ratio of △α > 3° in the test group was also significantly smaller than that of the control group (P=0.048).Conclusion: The novel tibial sighting device combined with intramedullary femoral localisation provided the surgeon a better surgical view in sagittal tibial osteotomy and improved the accuracy of tibial implant alignment in UKA. This method makes the vertical osteotomy of the tibial platform simpler, more precise and highly repeatable.