Anatomic tibial component design can increase tibial coverage and rotational alignment accuracy: a comparison of six contemporary designs

Abstract

PurposeThe aim of this study was to comprehensively evaluate contemporary tibial component designs against global tibial anatomy. We hypothesized that anatomically designed tibial components offer increased morphological fit to the resected proximal tibia with increased alignment accuracy compared to symmetric and asymmetric designs.MethodsUsing a multi-ethnic bone dataset, six contemporary tibial component designs were investigated, including anatomic, asymmetric, and symmetric design types. Investigations included (1) measurement of component conformity to the resected tibia using a comprehensive set of size and shape metrics; (2) assessment of component coverage on the resected tibia while ensuring clinically acceptable levels of rotation and overhang; and (3) evaluation of the incidence and severity of component downsizing due to adherence to rotational alignment and overhang requirements, and the associated compromise in tibial coverage. Differences in coverage were statistically compared across designs and ethnicities, as well as between placements with or without enforcement of proper rotational alignment.ResultsCompared to non-anatomic designs investigated, the anatomic design exhibited better conformity to resected tibial morphology in size and shape, higher tibial coverage (92 % compared to 85–87 %), more cortical support (posteromedial region), lower incidence of downsizing (3 % compared to 39–60 %), and less compromise of tibial coverage (0.5 % compared to 4–6 %) when enforcing proper rotational alignment.ConclusionsThe anatomic design demonstrated meaningful increase in tibial coverage with accurate rotational alignment compared to symmetric and asymmetric designs, suggesting its potential for less intra-operative compromises and improved performance.Level of evidenceIII.

Which Tibial Tray Design Achieves Maximum Coverage and Ideal Rotation: Anatomic, Symmetric, or Asymmetric? An MRI-based study

“…Dai et al investigated anatomic, symmetric, and asymmetric trays in multiple ethnicities for healthy knees [10]. Our findings of increased surface coverage with more ideal rotation with the anatomic tray are consistent with those investigators' findings, suggesting that the anatomic tray better optimizes the relationship between coverage and rotation for both healthy and arthritic knees.…”

“…An anatomic tibial tray was recently developed in an effort to better match patient anatomy compared to symmetric and asymmetric trays. The relationship between tibial coverage and rotation has been investigated for the anatomic design in healthy knees [10]. However, it has yet to be determined for patients undergoing TKA which tray among anatomic, symmetric, and asymmetric designs optimizes the relationship between tibial surface coverage and rotation.…”

Early Clinical and Radiological outcomes of the New Anatomic Knee System : Minimum 3-year Follow-up.

“…Internal rotation of tibial or femoral components has been linked to poor clinical outcomes [10,11]. It has also been reported to be a major cause of pain and functional problem after TKA [11][12][13]. Therefore, ensuring proper rotation of the components is key to a successful TKA surgery.…”

“…Therefore, ensuring proper rotation of the components is key to a successful TKA surgery. However, focusing only on the ideal rotational alignment may compromise the other surgical objectives, including component overhang and bony coverage [13].…”

Anthropometric measurements of the knee: time to make it fit

“…The coverage of the tibial bone by a non-anatomical component is about 85-87 %. This bony coverage increases up to 92 % when anatomical designs are used [3]. The non-anatomical design requires internal rotation of more than 5° for compensation in 39-60 % of patients in order to improve the bony coverage.…”