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International Journal of Bioprinting 3D-printed assembly anatomical patella fracture bone plate

Figure 2. AATBP design concept with an anatomical curved surface of 1.6-mm thickness, including a DP with 0.4-mm thickness to ratchet onto the
proximal plate (PP) for height adjustment.

curved surface was intended to adaptively fit to the patella to allow selective bone screw insertion to fix the AATBP
surface curvature. The curved surface was obtained using to the fractured patella. A straight slot in the DP was also
a standard artificial patella made of polyurethane foam designed to allow the screw insertion accompanied by the
(Sawbones; Pacific Research Laboratories Inc., Vashon, adjustment of AATBP height. Ten 1.5-mm wire holes were
WA, USA). This was used to capture the patella surface created in the PP to allow the band wire to pass through,
via a computed tomography (CT) scan, followed by thereby enhancing the fixation capability when necessary.
reconstruction in image processing software (Mimics 22.0; Cone bumps with a height of 0.6 mm were designed and
Materialize NV, Leuven, Belgium). The AATBP thickness randomly distributed onto the back of the PP, i.e., the
was designed to be 1.6 mm, which was divided into two surface contacting the bone surface, to increase bone plate
thin pieces at the proximal and distal parts. The distal plate and patella retention (Figure 2).
(DP; 0.4 mm in thickness) can be ratcheted and assembled To verify the AATBP anatomical surface design
onto the center of the proximal plate (PP). These two plates feasibility, we randomly selected two males (48 and 71
can be adjusted to extend the fixation total height from years old) and one female (74 years old) from the CT
38 to 50 mm to fit the relative positions according to the database and reconstructed their complete and normal
patella size (Figure 2). patella image models. The AATBP and three normal
Two pairs of hooks were designed onto the DP and PP patella models were imported into CAD software (PTC
edges that can pass through the tendon to grip the fractured Creo V6.0; PTC Inc., Needham, MA, USA) to evaluate the
patella fragments. Eleven locking and two compressive fitness (gap distances) between AATBP and three normal
screw holes (2.4 mm in diameter) with medial–lateral patellae on the inferior surface. The AATBP midline and
symmetry in the PP and DP, respectively, were also created each patella were aligned first. The total height (proximal–

Volume 9 Issue 6 (2023) 173 https://doi.org/10.36922/ijb.0117