Tibial cutting guide holding pins position reduces the risk
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Excessive pin holes made for cutting guide stabilization have been linked to periprosthetic fracture of the tibia after unicompartmental knee arthroplasty. However, fractures have been identified in cases where the manufacturer's recommended method of using two pins was used.

Finite element models were constructed using Chinese female bone computed tomography images, with bone cuts made according to the surgical steps of implanting a fixed bearing unicompartmental arthroplasty. Four combinations of pinholes (pins placed more closely to the medial tibial cortex or centrally along the mechanical axis as allowed by the tibial cutting guide) created for tibial cutting guide placement were tested by finite element analyses. Testing loads were applied for simulating standing postures. The maximum von Mises stress on the tibial plateau was evaluated.

Results:
--Pinhole placed close to the medial edge of the proximal tibial plateau is associated with the highest stress (27.67 Mpa) and is more likely to result in medial tibial fracture.

--On the contrary, pinhole placed along the central axis near the tibial tuberosity has the lowest stress (1.71 Mpa) and reflects lower risk of fracture.

Finally, the current study found that by measuring the associated stress in different pin hole positions using finite element analysis, positioning tibial cutting guide holding pins centrally would reduce the risk of periprosthetic fracture of the medial tibial plateau.

Source: https://josr-online.biomedcentral.com/articles/10.1186/s13018-021-02308-6
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